CA1259514A - Photosensitive ceramic coating composition - Google Patents

Abstract

TITLE
PHOTOSENSITIVE CERAMIC COATING COMPOSITION
ABSTRACT
A photosensitive ceramic coating composition which is fireable in a substantially nonoxidizing atmosphere comprising an admixture of:
(a) finely divided particles of ceramic solids having a particularly defined surface area-to-weight ratio and particle size, and (b) finely divided particles of an inorganic binder having a particularly defined surface area-to-weight ratio and particle size, dispersed in an organic medium comprising (c) an organic polymeric binder and (d) a photoinitiation system, dissolved in (e) photohardenable monomer and (f) an organic medium.

Description

~L~25~J5~

TITLE
PHOTOSENSITIVE CERAMIC COATING COMPOSITION
Field of I~nvention The invention relates to photosen6itive 5 ceramic coating compositions and, in particular, to such co~po~itions in which the ceramic component is a dielectLic ~aterial.
Ba~kqround of the Invention Multilayer thick film circuits have been 10 used for ~any years to increa6e CilCUit functionality per unit of area. ~oreover, recent advances in circuit technology have placed new demand~ o~
dielectric material~ for thi6 use. Heretofore, ~o~t of the dielectric ~aterials used in multiple circuits 15 have been conventional thick film dielectric compo6itions. These are coMpri6ed of finely divided particles of dielectric 601ids and inorganic binders dispersed in an inert organic medium. Such thick film materials are usually applied by 6creen 20 printing, though they may be applied by other means a6 well.
Thick film mate~ial6 of this type are very important and will continue to be 60. However, when applying the~e thick fil~ material~ by screen 25 printing, it ~6 difficult to obtain better than 8 mil (203 ~m) line and space resolution. In fact, to obtain even thi~ level of performance, it i6 essential that all the ~creen printing variables such as ~creen quality, 6queegee hardness, print speea, 30 disper~ion propertie~, etc., be mos~ careSully controlled and constantly aonitored to obtain good product yield6. Similar problems exi6t, of cour6e, with the use of thick ~ilm conductor and resistor materials.

i;14 One app~oach ~o thi6 problem i~ (1) to apply a layer of the diele~tric aaterial to a su~strate by mean6 of di~per~ion in a photo~ensitive medium, (2) to expo6e the layer imagewi~e to actinic radiation, (3) to 601vent develop the pattern to remove unexposed portion6 of the layer, and (4) to fire the remaini~g expo~ed por~ion~ of ~he pattern to remove all remaining organic materials and to ~inter the inorganic material~. ~his technique i5 revealed in 6everal issued patents ~uch a6 V.S. 3,443,944 to Wise, U.S. 3,615,457 to Seiber~, U.S. 3,958,996 and U.S. 3,982,941 to In6kip, U.S. 3,677,950 to Felten and U.S. 3,914,128 to Scheiber et al. None of the6e ~y6tem6 utilize6 an inorganic binder. However, U.S.
3,355,291 to Baird et al. and U.S. 3,573,90B to ~inetei describe a method for applying gla66 to a ~emiconductor device by applying a photosen6itive paste of the glas~, exposinq, solvent developing and firing the exposed areas.
Notwith6tanding the effectivene66 of the prior art proce66e6 for ~pplying ~uch electronic material6 a6 a pa6te, it would be even better to apply æuch ~aterials as a dimen6ionally stable film.
~here are ~everal advantage~ to the use of film, including: (1) better surface uniformity, (2) better layer thi~kne6s uniformity, (3) a thicker layer can be applied, thu6 takinq fewer step6 to achieve thick fired dielectric layers, (4) greater proces6ing uniformity, (5) longer ~torage life, (6) minimum sen~itivity to dir~ pickup, and (7) no ~igni~icant ~ change in vi~c08ity a~ compa~ed to the vi6co~ity ! change6 which take place in pa6te6 due to drying on the printing screen. Consequently, there i6 a 6tronyly unmet need for ceramic disper~ion6 which can be applied by either conventional method6, ~uch as 6creen p~inting where approprîate, or a~ a laminated film where ~ore exacting propertieç are required.
Summar~ of the Invention In it6 primary aspect, the lnvention i6 directed to a photo6en~itive cera~ic coating composition ~hich i8 fireable in a substan~ially nonoxidizing atmo~phere comprisin~ an admixture of ~ a) finely divided parti~le6 sf ceramic 601id6 having a surface area-to-weiqht ~atio of no ~ore than 10 m2ig and at least 75 wt. t of the particle~ having a size of 1-10 ~m.
~ b) finely divided particle6 of an inorganic binder having a surface area-to-~eigh~ ~atio of no ~ore than 10 ~2/g and at lea~t 95 ~t. t, of the particle~ having a 6ize of 1-10 ~m, the weight ratio of (b) eo (a) being 0.6-2, di6per6ed in an organic ~edium compri~ing (c) an organic polymeLic binder 6elected from the group con~i6ting of (1) homopolymer and copolymer6 of Cl 10 alkyl acrylate6. ~Cl 10 alkyl methacrylates, alpha-~ethyl6tyrene and 0-2 wt. %
e~hylenically unsaturated carboxylic acid, amine or ~ilane-containing compound6, (2) homopolymer~ and copolymer6 of Cl_10 mono-olefins, (3) homopolymer6 and copolymers of Cl ~ alkylene oxide and ~ixture6 thereof, the binder compri6ing 5-25 wt. % basi6 ~otal inorganic eolids, and (d) a photoinitiation sy6tem, di~eolved in (e) photohardenable monomer and (f) volatile nonaqueou6 o~ganic solvent.
In a secondary a~pect, the invention i~
directed to a photo6en6itive ce~amic film compri6ins a layer of the above-de~cribed photosen6itive composition from which the solvent ha6 been removed by volatilization.

~L~i9~;~4 In a still fu~thec a6pect, the invention is directed to a patterned ceramic layer compri6ing the above-d~6cribed photosen6itive ceramic film which ha6 been: (1) laminated to a ceramic substrate, (2) exposed imagewise to actinic radiation to effect hardeniny of the exposed areas of ~he film, (3) soivent developed to remove unexposed areas of the film, and (4) fired in a substantially ~onoxidizing atmosphere to effect volatilization of the organic aedium and sintering of the inorganic binder and ceramic solids.
DETAILED DESCRIPTION OF THE INNENTION
A. Ceramic Solids The invention is applicable to virtually any high melting inorganic solid material. HoweverO it is particularly suitable for ~aking disper~ions of dielectric solids ~uch as alumina, titanates, zireonate~ and 6tannates. It i8 also applicable to precursor6 of such materials, i.e., solid ~aterial6 which ueon firing are converted to dielectric solid6, and to mixture~ of any of these.
Among the many dielectric solid6 which are likely to be u6ed in the invent~on a~e BaTiO3, CaTiO3, srTio3~ PbTiO3, CaZrO3, BaZrO3, CaSnO3, BaSnO3, and ~123 AB will be apparent to those skilled in the ceramic arts, the exact chemical composition of the ceramic ~olids to be used in the composition of the invention is not ordinarily critical in the rheolo~ical ~ense. It i6 also preferred that the ceramic eolids not have swelling characteri~tics in the organic di~per~lon 6ince the rheological properties of the dispe~sion may be ~ubstantially changed thereby.
lt has been found that the dispersion of the invention mu6t contain no significant amount of 1~95~

solids having a parti~le ~ixe of les6 ~han 0.3 ~m in order to obtain adequately complete burnout of the organic medium when the fil~s or layer~ thereof are fired to remove the organic ~edium and to effec~
~interi~g of the inorganic binder and the ceramic 601id6. ~o~ever, none of the ceramic solid6 ~ay exceed 20 ~m and, furthermore, at lea~t 75 wt. t of the ceramic solid6 ~u6t have a ~ize of 1-10 ~m.
When the di6per6ion6 are u6ed to make ~hick ilm pa~te6, which are usually applied by screen priuting, the maximum particle 6ize ~u6t not exceed the thîckne6s of the 6creen, and when t~e di6per6ion i~
used to ~ake dry photo~en6itive film, the maximum paLticle ~ize mu6t not exceed the thickne6s of the lS film. It is preferred that at lea6t 90 wt. ~ of the ceramic solids fall within the 1-10 ~m range.
In addition, it i6 prefeEred ~hat ~urface area/weight catio of the ceramic particle6 not exceed 10 ~2/g for the rea~on that ~uch particle6 tend to affect adver6ely the sintering characteri6ticR of the accompanying inorganic binder. It i6 still further preferred that the 6urface area/weight ratio not exceed 5 ~2~g. Ceramic particle6 having a ~urface area/weight ratio of 1-5 have been found to be quite 6ati8factory.
B. Inorqanic Binder The glas6 frit u6ed in the pre6ent invention aid6 in ~intering ehe inorganic cry6talline particulate6 and may be of any well known composition which tlaR a melting temperature below that of the ceramic ~olids. ~everthele~6, in order to qet adequate her~eticity of the device6, it iB preferred that the glass tran6ition temperature (Tg) of the inorganic binder be 550-825C and still more 35 preferably 575-750C. lf melting takes place below 550C, organic material will likely be encap6ulated and bli6ter~ will ~end ~o form in the dielectric layer a~, the organic6 de~Qmeose. On the oeher hand, a glas6 tran6ition temperature above 825C will tend to pro~uce a porvu~ dielectric when 6intering temperature6 compa~ible wi~h copper ~etalliza~ion6, e.g., 900C~ a~e usd.
The gla~fi f~it~ mo~t preferably u6ed are the boro6ilicate frits, ~uch a~ lQad borosili~a~e frit, bi~muth, cadmium, barium, calciu~ or other alkaline earth borosilicate frit~. The preparation of 6uch gla6 frit~ i~ well ~nown and con6i~e6, for ~xample, in ~elt.;ng together the constituen~ of the gla6~ in the form of the oxide~ of the con tituen~6 and pourin~ 6uch ~olten ~ompo6ition into water to form the ~rit. The batch ingredient6 may, of course, be any compound that will yield the desired oxide~ under the u6ual conditions of frit production. For example, boric oxide will be ob~ained from boric acid, 6ilicon dioxide will be produced f~om flint, barlum oxide will be produced from barium earbonate, etc. The 5~1a66 i5 preferably milled in a ball mill with water to ~educe the particle size of the frit and to obtain a frit of substantially uniform ~ize.
~t i6 then settled in water to 6eparate fine~ and the superna~ent fluid containing the fine6 is removed.
Other method~ of cla~6ification may be u6ed as well.
The gla66e6 are prepared by conventional glas~making technique6, by ~ixing the de6ired component~ in the desired proportlQns and heatin~ tha ~ixture to form ~ melt. A~ 1~ well known in the art, heatinq i~ conducted to a peak temperature and for a time 6uch that the melt becomeb entirely liquid and homogeneolls. In the pre6ent work, the component6 are premixed by ~haking in a polyethylene jar with plas~ic b~ and then melted in a platinum crucable at the desired temperatuLe. The melt i6 heated at the peak temperature for a perivd of 1 to 1-1~2 hour~. The melt i~ then poured into cold water. The maximum temperature of the wa~er during quenching i6 kept as low afi po6sible by increasing the water-to-melt ratio. The crude frit after 6epa~ation from water i~ freed of residual ~ater by drying in air or di~placing the water by rinsing with methanol. The crude frit i~ then ball milled for 3-5 ~ours in alumina containers using alumina ball6.
Alumina contamination of the frit i~ not within the ob~ervable limit of x-ray diffraction analysis.
After di~charging the milled-frit 61urry from the mill, exce6~ 601vent iB removed by decantation and the frit powder is air dried at room temperature. The dcied powder i6 ehen screened through a 325-me~h screen to remove any large particles. The inorganic binder, like the ceramic solids, should have a surface-to-weight ratio of no ~ore than 10 m /g and at least 95 wt. % of the particles should have a particle Eize of 1-10 ~m.
It is preferred that the 50~ point of the inorganic binder. which i6 defined a6 equal parts by weight of both larger and smaller particle6, be equal to or le~ than that of the ceramic solid~. For given particle size ce~amic ~olids, the inorganic binder/ceramic solids ratio required to achieve her~eticity will dec~ease a6 the inoLqanic binder 6ize decrea~e6. With a givRn ceramic solid~-inorganic binder system, if the ratio of inorganic binder to ceramic solid6 is ~ignificantly higher than that required to achieve hermeticity, the dielect.ric layer tencl6 to form blister6 on firirlg.
If the ratio i6 sigrlificantly lower, the fired dielect:ric will be porous and therefore nonhermetic.

~3!L ~ ~D ~ S ~

~ ithin ehe abo~e-de6c~lb~d part;cle 6ize and ~urface area limi~ is neverthele~ preferred that the inorganic binde~ particle6 be 1-6 ~m. The rea~on for thi~ i8 ~at smaller particle~ haYing a 5 high sur~ace area tend to ad60rb the o~ganic ~aterial6 a~d thu6 i~pede clean decompo~ition. On the other hand, la~ger 6ize particle~ tend to have poore~ ~inte~ing c~aracteri6tic~. It i6 prefer~ed tha~ the ratio of inorqanic binder to ceramic eslid6 be 0.6-2~
C. Orqanic Pol~meric Binder A6 set out hereinabove, the binder component of the di~per~ion of the inven~ion i~ an organic polymeric binder fielected from the g~oup con6i6ting of (1) homopolymer and copolymer6 of Cl 10 alkyl acrylateg, Cl 10 ~kyl methacrylate6, alpha-~ethyl-~yrene and 0-~ wt. ~ ethylenically unsaturated carboxylic acid, amine or silane-containing compoundE;, (2) homopolymer6 and copolymers of Cl 10 ZO ~ono-olefinE~" ~3) homopolymer6 and copolymer6 of Cl 4 alkylene oxide and ~ixtures thereof, the bindeE compri~ing 5-25 wt. % ba~i6 total ino~ganic fiolid6.
The above-deE;cribed polymer6 include ho~o-polymer~ aE; well as random copolymer~ and highermultipo:Lyme~fi. The relative quantity of carboxylic acid or amine di6tributed along the polymer ~hainE;
~hould be rlo more than 2.0 wt. ~. Becau6e they are cleane~ burning ~n low-oxygen atmo6p~eres, methacrylic polymer~, e6pecially poly(methyl methacrylate), are preferr~ed over acrylic polymer~.
It i~ p~Qfe~red that the comonomeL6 containing functional moietie~ not exceed 1~.0 wt. t of any one polymer or 2.0% in the polymer mixture to 3~ avoid flocculation of the di~per6ed ceramic ~olid6.
In some in~tance~, it ha6 been ob6erved that polymer 1~ 5 9 5 ~

mixtur2~ having as low a~ 1.8% acid-containing monomer~ may be borderline or even unsati~factory with respect to disper6ion charæcteri6tic6. In mo~
in6tance~ of thi~ kind, ~uch polymer~ can, neverthel~6s, Etill be u~ed in the invention by employing a more polar 601vent. Thus, while a polymec mixture ccntaining a~ much as 2.0 ~onomer-containing functional group6 can be u6ed, ~uch polymer mixture6 ~aving only 1.5~ functional monomers are prefer~ed. No more than 1.0 wt. ~ of 6uch furlctional monomer~ iB ~till further preferred.
It i6 also preferred for the ~ame reason that none of the poly~er6 contained in the polymeric mixture ~ontain more than 10.0 wt. % functional comonomer.
Thus, the polymeric binder can be a mixture of polymer6, some of which contain no functional moietie~ at all and 60me of which con~ain a6 much a~
10.0 wt. ~ functional comonomer~ so long a6 the content of functional comonomers in the total mixture is within the range of 0.2-2.0 wt. t. On the othec hand, i~ i~ p~eferred that the poly~eric binder be compri6ed mo6tly of ~ethacrylic poly~ers a6 defined above ~hich contain 0-5.0 wt. % functional comonomer.
Suitable copolymerizable carboxylic acid6 include ethylenically un6atur3ted C~ 6 monocarboxy:Lic acids ~uch as acrylic, ~ethacrylic and crotonic acids and C4 10 dicarboxylic acid6 such a6 fumaric, itaconic, citraconic, vinyl succinic and maleic acid6 as well a6 their half efitec~ and, where appropriate, their anhydlide6 and mixture~ thereof.
Becau~e they are cleaner burning in low-oxygen atmosphere6, methacrylic polymers are preferred over acrylic polymecs.
lt i6, of ~our6e, recognized that certain amine con6~ituent~ cannot be incorporated in the chain directly by copolymecization of the amine-~olltaining monomer but may be irlco~pora~ea indire~tly by po~polymerization rea~tion of a pendant reactive moiety of the polymer chain.
Illu~tralCive o t~i~ are primary amine6 which can be added by reaction of ylycidyl compound6 with pendant carboxylic acid group~ in the prefience of ammonia.
Thu6, a~ u~ed herein, the term "ethylenically un~aturated amine" is intended to include polymer6 derived flom both amine-containing comonomec6 as well a~ other comonomer~ which have been postpolymerizationally reacted to fo~m amine group~
thereon. Primary, secon~ary and tectiary amines are each effective in a similar manner. Suitable lS comonomer6 for direct incorpo~ation of pendant amine groups into the binder polymer chain include ~iethylaminoethyl methacrylate, dimethylaminoethyl methacrylate and t-butylaminoethyl methacrylate.
Suitable comonomer~ ~hich yield pendant functional moieties 6uitable for po6tpolymerization reaction to incorporate amine unctionality include t~e above-de~c~ibed ethylenically un6aturated viz~
epoxide~ such a6 glycidyl acrylate or glycidyl ~ethaccylate.
~ hin the above-de~cribed limit6 for the nonacidic comonomer~, it i~ preferred that the alkyl acrylate or methacrylate con6titute at lea6t 75 and pLeferably B0 wt. t of the polymer.
The polymecic bindec can contain up to about 10 wt. '~ of other nonacrylic and nonacidic comonomer6 ~uch a6 ~tyrene, acrylonitrile, vinyl acetate, acrylamide and the like~ BO long a6 the previoufily di6cu~6ed compo6itional criteria are ~et a6 well a6 the physical sciteria mentioned ~elow. ~owever, it i6 preferred to u~e not more than about 5 wt. ~ of ~uch monomer6 becau~e ther are more difficult to bu~n out ~leanly. At present, the u~e of ~uch other comonome~ i6 not known ~o add to the efficacy of the copolymer6 in their application to the inventivn.
~owever, 6uch comonomers in the above~ ted amount6 do not detract from ~he effectivene~s of the polymer~
~o long a~ all the compo6itional and phy6ical proper~y criteria are ~et.
- In addi~ion to the above descrlbed ac~ylic and methacrylic polymer6, variou~ polyolefins ~uch a~
polyethylene, polypropylene, polybu~ylene, polyi~obutylene, and ethylene-propylene copolymer can al~o be u6ed. Al~o u6eful in the invention are the so-called polyether~ ~ich are polymer6 of lowe~
alkylene oxide~, suc~ a~ polyethylene oxide, polypropylene oxide and polybutylene oxide.
In addi~ion to the above-de6cribed compo~itional parameter6, certain phy6ical properties of the polymeric binder are, of cour6e, important.
ln particular, it will be recognized ~y tho~e 6killed in the p~otorefi~st art that the unexpo6ed binder polyme~ ~u6t be ~ubstantially developable in whatever ~olvent developer i6 used. On the other ~and, the photohardenea binder must have 6ufficient 601vent re6i6tance that ~t ~ not wa~hed off by the developer 601ven~.
Polymer~ meeting the6e criteria can be made by tho~e ~killed i~ the art of ~crylate polymerization by conventional solution polymerization techniques. Typically, ~uch acidic acrylate polymer~ are prepared by combininq an alpha, beta ethylenically un~aturated acid wi~h one or more copolymerizable ~inyl monomers in a relatively low boiling ~75-150~C) organic 601vent to obtain a 20 to 60~ ~olution of the ~onomer mixture, then ~:25~S~
1~
~ub~equently ~au~ing the monomer6 to polymerize by the addition of a polymerizatiQn ca~aly6t and heating the mixture at the ~eflux temperature of the solution at atmo~phe~ic pre~ure. After the polymerization reaction i6 e~sentially complete, ~he re~ulting acid polymer ~olu~ion i6 cooled to room temperature and sa~ple6 are removed to determine the vi~cosity, ~olecula~ weight, acid equi~alent, etc. of the polymer.
D. Photoinitiation Sv~tem Suitable photoinitiation sy6tem~ a~e tho6e which are thermally inactive but which generate free radicals upon expo~u~e to actinic light at or below 185~C. The~e include the ~ub~tituted or un6ub6tituted polynuclear quinone~ which are compound6 having two intracyclic carbon atom~ in a conjugated ~arbocycli~
ring 6y6tem, e.g., 9,10-anthraquinone, 2-~ethylanthra-quinone, 2-ethylanthraquinone, 2-tert-butylanthra-quinone, octamethylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthrenequinone, benz(a~anthracene-7,12-dione~ 2,3-naphthacene-5,12-dione, 2-methyl-1,4-naphthoquinone, 1,4-dimethyl-anthraquinone,

2,3-dimethylanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, retenequinone, 7,B,9,10-tetrahydronaphthacene-5,12-dione, and 1,2,3,4-tetrahydrobenz(a)anthracene-7,12 dione.
O~her photoinitiator6 ~hich ace al~o useful, even though ~ome may be thermally active at temperature6 a~ low a6 85C, are de6ccibed in U.S. Patent 2,760,863 and lnclude vicinal ketaldonyl alcohols ~uch as benzoin, pivaloin, acyloin ethers, e.g., benzoin methyl and ethyl ethers; a-hydcocacbon-sub6tituted aromatic acylQins, includinga-methylbenxoin, a-allylbenzoin and a-phenylbenzoin. Photoreducible dyes and reducing ~5~

agent~ di6clo~ed in U.S. Pa~ent~ 2,850,~45, 2,875,0~7, 3,0g7.056, 3,074,974, 3,097,097, and

3,145,104, a6 ~ell a~ dye6 of the phenazine, oxazine, and quinone Cla6~eE, ~ichler'~ ketone, benzophe~one, 2,4,5 triphenylimidazolyl dimers with hydrogen dsnor&
including leuco dye~ and mixture~ ehereof a~
de~cribed i~ ~.S. Pa~ent6 3,~27,161, 3,~79,185, and 3 ~ 549, 3fi7 can be ~ed a~ i~itiaeor~. Al~ u~eful with pho~oi~itiatos and photo;nhibitor6 are &en~itizer~ di~closed in U.S. Patent 4,162,162. The photoinitiator or photoinitiator 6ystem i6 present in 0.05 ts 10% by ~eight ba6ed on the total weight of the dry photopolymerizable layer.
~. photohardQl~L~ o~
The photohardenable monomer component of the invention i~ compri62d of at lea6t one addition polymerizable ethylenically un6aturated compound having at lea6t one polymerizable ethylenic group.
Such ~ompounds are capable of forming a high polymer by free radical initiated, chain propagating addition polymerization. preferably~ the unsaturated ~ompound (~onomer) hafi at least two terminal ethylenically un6aturated group~, e.g., 2 to 4 group~. The monomeri~ c~ompounds are nonga6eou~. That ic, they have a nor~al boiling point above 100C and a pla~eicizing action on the organic polymeric binder.
Suitable monomer~ which ~an be u6ed alone or in eombination w;~h other monomer~ include t-butyl acrylate and methacrylate, 1,5-pentanediol diacrylate and dimethacLyla~0, N.N-diethylaminoethyl acrylate and methacrylate, ethylene glycol diacrylate and dimethacrylate, 1,4-butanediol diacrylate and dimethacrylate, diethylene glycol diacrylate and dimethacrylate, hexamet~ylene glycol diacrylate and dimeehacrylate, 1,3--propanediol diacrylate and dimethacrylate, decamethylene glycol diacrylate and dimethacrylate, 1,4-cyclohexanediol diacrylate and dimethac~ylate, 2,2-dimethylolpropane diacrylate and dimethacrylate, glycerol diacrylate and dimethacrylate, tripropylene glycol diacrylate and dimethacrylate, glycerol triacrylate and trimethacrylate, trimethylolpropane ~riacrylate and trimethacrylaSe, pentaerythritol triacrylate and trime~hacrylate~ polyoxye~hylated tri~ethylolpropane triacrylate and tri~ethacrylate and similar compounds a~ disclo~ed in U.S. Patent 3,3~0,831, 2,2-ditp-hydroxyphenyl)-plopane diacrylate, pentaerythritol tetraacrylate and tetramethac;ylate, 2,2-di-(p-hydroxyphenyl3-proæane dimethacrylate, triethylene glycol diacrylate, polyoxyethyl-2,2-di~(p-hydroxy-phenyl~propane dimethacrylate, di-(3-methacryloxy-2-hydroxypropyl) ether of bi~phenol-A, di-~2-methacryloxyethyl) ether of bisphenol-A, di-~3-acryloxy-2-hydroxypropyl) ether of bisphenol-~, di-~2-acryloxyethyl) ether of bisphenol-A, di-(3-methacryloxy-2-hydroxypropyl3 ether of 1,4-butanediol, triethylene glycol di~ethacrylate, polyoxypropyltrimethylol propane triacrylate, butylene glycol diac~ylate and dimethacrylate, 1,2,4-butan,etriol triacrylate and trimethacrylate, 2,2,4-trimethyl-1,3-pentanediol diacrylate and di~ethacrylate, l-phenyl ethylene~l,2-dimethacrylate, diallyl fu~arate, ~tyrene, 1,4-benzenediol dimethacrylate, 1,4-dii~opropenyl benzene, and 1,3,5-trii60propenyl benzene. Al~o useful are ethylenically un~aturated com2ounds having a molecular weight of at least 300, e.g., alkylene or a polyalkylene glycol diacrylate prepared fcom an alkylene glycol of 2 to 15 carbon~ or a polyalkylene et21e~ qlycol of 1 to 10 ether linkages, and tho6e difi~losed in ~.S. Patent 2~927,022, e.g., tho~e havins a plu~ality of addition polymerizable ethylenic linkage~ par~icularly when pre~ent a6 terminal linkage6. Particularly preferred ~onomer6 a~e polyoxyethylated trimethylolpropane triacrylate, ethylated pentaerythritol triacrylaSe, dipen~aerythsitol ~onohydroxypentaacrylate and l,10-decanediol dimethylacrylate. The un~aturated ~onomeric componen~ i~ pre~ent in an amount of 5 to 45% by weight ba~ed on the total ~eight of ~he dry photopolymerizable layer.
Parti~ularly preferred photohardenable ~onomer~ for u6e in the invention because of their superior burnout cha~acteri~tic6 are certain mono-, di- and tci-functional methacrylate~ corre~pondin~ to the ollowing chemi~al ~tructures:
,c~3 (I~ CH2=C-C=0 Monofunctional Monomer o 1 , 3 c~3 25 (Il)CH;,~C-C=0 Difunctional Mono~er o CH2 " , 3 (III) CH2=C-C=O Trifunctional Monomer o ", 3 R3 C C~2 O C C C~2 CH -O C-C=C~2 ;2 ", In all of the above three type~ of methacrylic ~onomer6, the alpha-~arbon ~u6t have 2 or 3 hydroqen atom~ ~ub~tituen~ depending on ~hether the be~a--carbon i~ prefient (2 hydrogen atom~) or abfient (3 hydrogen atoms). In addition, if the beta-carbon i absent. it ig repla~ed by a hydrogen atom aL i6 the case with ~ethyl metha~rylate. On the other hand, if the beta-carbon i~ pKesent, Rl, R2 and R3 are lndependently ~elected from alkyl, aryl or aralkyl group~ or, if one of the three R qroup6 i6 H, then the other ~wo R geoups are preferred to be selected from alkyl, aryl or aralkyl group6.
Examples of the Por~er are 2,2-dimethylpropane dimetha~rylate ~DMPD~h) and trimethylolpropane trimeth2cry1ate (TMPrMA).
Mimor amounts of other component6 can be pre6ent in the photopolymerizable compo6ition6, e~g., pigment6, dye6, thermal polymerization inhibitor6, adhe6ion promoter~, 6uc~ as ocgano6ilane coupling agent6, pla~ticizee6, coating aid6 ~uch as polysthylene oYide~, et~ so long a6 the photopolymer~zable co~po~itions retain their - e~6ential properties. Organosilanes aLe particularly u6eful in quantities of 3.0 wt. % or le~6 based on the weight of t~e inorganic particle6. Treated particle~ haYe a lower demand for organics. Thu6, the level of organic6 in the coating can be reduced, which result6 in ea~ier burnout upon fiEiDg. The organo6ilane can al~o improve the difiper6ion properties and allow a lower inorgani~ binder/ceramic ~olid~ ratio at equivalent hermeticity.
F. Or~anic Medium The ~ain purpo6e of the organic ~edium i6 to ~erve a~ a vehicle ~or disper~ion of the finely 1~ divided &slid6 of ~he compo6ition in 6uch form that it can readily be applied to a ceramic or other ~ub~trate. Thus, ~he organic m0dium mu6t fir~t be one in which the ~olid~ are di6p~r6ible ~ith an adequate deg~ee of stability. 5econdly, the rheological propertie6 of the organic medium must be such that they lend good application propertie to the disper~ion.
When the diseersion i6 tc be made into a film, the organic medium in which the ceramic solid~
and inorganic binder are di6per6ed con6i~ts of the above-de6cribed polymeric binder, monomer and initiator which are di6solved in a volatile organic ~olvent and, optionally, other di6solved material~
6uch a6 plasticizers, relea~e agent6, di6per6ing agent6, ~tripping agent~, antifouling agent6 and wetting agent6.
The solvent component of the organic medium, which may be a mixture of solvent6, i~ cho6en ~o as to obtain ~omplete solution therein o~ the polymer and to be of ~ufficiently hi~h vol~tillty to ~nable the ~olvent to be evaporated ~rom the di~per~ion by the application of relatively low level~ of heat at at~o6pheric pre66ure. In addition, the ~olvent mu~t boil well below the boiling point and decompo6ition temperature of any other additive6 contained in the 'lF

1~
organic ~edium. Thu6, 601vent6 having atmo6pheric boiling poin~6 below 150C are u~ed most frequently.
Such 601vents include ben~ene, acetone, Yylene, ~e~hanol, ethanol, ~ethylethyl ketone, s ~ eri~hloroethane~ tetrachloroethylene, amyl acetate~ 2,2,4 ~rie~hyl pentanediol-1,3-mono-i60butyrate, toluene, ~ethylene chloride. andethylene glycol monoalkyl and dialkyl ether6 such a~
ethylene glycol mono-n-propyl ether. ror ca6ting film~, ~ethylene chloride is particulally preferred becau6e of it6 volatility.
Fre~uently the organic medium will al60 contain one or more pla~ticizers which serve to lower the Tg of the binder polymer. Such plasticizers help to a66ure good lamination to ceramic gub6trates and enhance the developability of unexpo6ed area6 of the compo6ition. However, ~he u6e of ~uch ~aterial~
should be minimized in order to reduce the amount of organîc materials which mu~t be removed when the films ca~t therefrom are fired. The choice of pla6ticizers i6~ of cour~0, determined primarily by the polymer which must be modified. Among the pla6tici~er~ which have been used in various binder sy6tem6 arle diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, dibenzyl phthalate, alkyl pho6phate6, polyalkylene glycol6, glycerol, poly~ethylene oxide6), hydroxy ethylated alkyl phenol, tricre6yl pho6phate tr~ethyleneglycol diacetate and polye6ter pla6tici~er6. Dibutyl phthalate iB frequently u~ed in acrylic polymer ~y6tems becauGe it can be u~ed ef~ectively in relatively 6mall concentratlon~.
The photo~en6itive compo6ition6 of the invention will frequently be employed a6 the photo~en6itive layer of a resi6t element in which the photo6ensitive layer i6 coated upon a 6upport film.

lB
.~.

.D ~-1~
In conventional pho~o}e~i6t elemen~6, it is nece~ary, or at lea~ highly de~irable. to protect ~he photo6en~i~ive layer by a remov~ble cover ~heet in order to prevent blocking between the pho~o~en~i~ive layer and the reverse surfa~e of the ~upport when they are ~tored in roll form. It i~
al~o desirable to protect the layer laminated to a ~ub~tra~e by ~eans of the removable ~upport film during imaging e~po6ure to prevent blocking between the layer and the phototool.
The photopoly~erizable compo~ition i~ coated upon tbe ~upport film at a ary coating thickne66 of abou~ 0.001 inch (~0.0025 cm) to about 0.01 inch ~~0.025 cm~ or more. A suitable 6trippable support which preferably has a high de~ee of dimensional 6tability to tempera~ure change~ ~ay be cho~en from a wide ~ariety of film6 compo6ed of high polymerg, e.g., polyamide~, polyolefin6, polye~ter6, vinyl polymers, and cellulose e~ter6 and may have a thickne~ of from 0.0005 inch (~0.0013 cm) to 0.008 inch (~0.02 cm) or ~ore. lf expo6ure i6 to be made before removing the strippable support, it mu6t~ of cour~e, tran~mit a sub~tantial fraction of the actinic radiation incident upon it. If the 6trippable support is removed prior to exposure, no ~uch re6trictions apply. A particularly ~uitable support il~ ~ransparen~ polyethylene terephthalate film having a thickne~6 of about 0.001 incb (~0.0~25 c~).
~hen an element contain~ no removable, ~rotectivs cover sheet and is to be stored in roll form, the reverse side of the ~trippable ~upport preferably has applied thereto a thin relea~e layer of a material such as wax or silicone to prevent blocking with the photopolymerizable 6tratum.

Alternatively, adhe6ion ~o the coated photopolymelizable layer may be preferen~ially increased by flame trea~ir.q or electrioal di6charge treating the ~upport ~urface to be coated.
Suitable remoYable, protective cover ~heets ~hen used may be cho6en from the ~ame grsup of high polymer film~ de~cribed above and ~ay have the 6a~e ~ide range of ~hicknes~es~ A cover sheet of 0.001 inch (~0.0025 cm) thick polyethylene i6 especially lQ ~uitable. Supeortfi and cover sheet6 a described above proYide good protection to the pho~opolymeriz-able re6i6t layer during storage prior to u6e.
lt ifi preferred that the weight ratio of the inorganic 601id6 (dielectric and glas6) to organic6 be within the ~ange of 2.0 to 6.0 and, more prefer bly, from 2.6 ~o 4.5. ~ ratio of no ~ore than 6.0 i~ ne~e6&ary to obtain a~equate di6per6ion and rheological propert;es. However, below 2.5, the amount of organic6 which mu6t be burned off i6 excessive and the quality of the final layer6 ~uffec6. The ratio of ino~ganic ~olid6 ~o organic6 i~ dependent on the parti~le ~ize of the inorganic ~olid~, the organic~ component& and on 6urface pretreatment of the inorganic solid6. ~hen the par~icle~ alre treated with organo6ilane coupling agent6, the ratio of inorganic &olid~ to organic6 can be inc rea&ecl. It i6 preferred to use a lower level of orc3anice; to minimize firing defect6. It i~
e&pecially important that the catio of inorgani~6 to organic~ be as high a6 po~sible. Orqano6ilane6 suitable for u~e in the invention are tho~e correspondinq to the general formula RSi(oR')3 in whicb R' iB methyl or ethyl and R i~ selec~ed from alkyl, ~ethacryloxypropyl, polyalkylene oxide or other organic functional group6 ~hich interact with the organic matrix of the film.

On ehe other hand, when the di~per6ion i~ to be applied as a ehick film pa~te, conventional thick film organi~ ~edia ~an be u6ed with app~opriate r~eological adjustment~ and the ~se of lower 5 volatil;ty solvents.
~ hen the comps6itions o~ ~he invention are formulated a8 thick film ~omposition~, they will u&ually be applied to a sub6trate by ~eans of screen printin~. Therefore, they ~ust haYe appropriate visc06ity BO tha~ ~hey can be passed through the screen readily. In addition, they ~hould be thixotropic in order that they set up rapidly after being 6creened, thereby giving good re~olu~ion.
While the rheological propertie6 a e of primary importance, the organic medium i6 preferably ormulated alfio to give appropriate wettability of the solid~ and the ~ubstrate, good drying rate, dried film 6trength ~ufficient to withstand rough handling and good f;ring propertie6. Satisfactory appearance of the fire~ compo~ition is alfio impo~tant.
In view of all these ~ eria, a wide variety of inert liquid~ can be used a~ organic media. ~he organic ~ediu~ for most thick film composition~ ls typically a ~olution of resin in a solvent and, frequently, a ~olvent solution containing both re6in and thixotropic agent. The solvent usually boils within the ranqe of 130-350~C.
Especially ~uitable resins for thi6 purpose are polymethac~ylates of lower alcohol~ and monobutyl ether of ethylene gly~ol ~onoacetate~
The most widely used ~olvents for thick fllm application~ are terpeneB such aB alpha- or beta-terpineol or mixtures thereof with other solvent6 such as kero6ene, dibutylphthalate, butyl Carbitol, butyl carbitol acetate, hexamethylene * denotes trade mark 2~
glycol ~nd hi~h boil~n~ ~1eOhO1B ana alcohol e6ter6.
VarloUS csmb~nations o~E the6e an~ othe~ ~olvents are formulated to obtain the Jesire~ ~isco~ity an~
volatili~y requi~er~e~ts for ea~h appll~a~io~.
s A~ong the th~xotropi~ a~ent6 ~hich a~e co~o~ly u~ed are Ihydroge~ate~ c~s~cor o~l and deriYatiYes t~ereo. It ~B, of cour~e, no~ always ~ecessary to lnco~porate ~ th~xotropic ~gent ~ce the ~ol~ent~resill propert~es couple~ wi~h ~he shear thinnlng ~n~erent ~n any ~uspen6~0n ~ay alone be ~uitable i~ this regar~.
T~e ratio . of olqan~ c ~e~ium to ~norganic SO1~S8 ~n the alspers~on6 ~ vary con6~erably ana depends upon the ~anner ln which the dispersion 1B to be applie~ an~ ~he kind of organi~ ~eaiu~ u6e~.
~or~ally, eo ac~ieve goo~ co~erage, the ~igper610n6 will contai~ complemeneally by wei~t 60-90~ ~olids ana 40-10~ organic ~edlu~. Su~h ~isper~ion~ a~e u~ually of ~e~ifluid con6i~ten~y and are referred to ~om~only ~E npa8~eB~.
The ~a8te5 aee conveniently prepa~e~ o~ a thfee~roll ~ill. The visco~ity o~ e~e pa~tee i6 typically viehi~ t~e fo~lowi~g ra~ges w~e~ ~ea~ura~
~t roo~ ~e~perature on Brook~iel~ vi6co~eter~ at low, ~oderate arld ~ig~ ~ea~ rates:
~hear Rate tSe~~l? Vi~ogity (Pa.
0.2 100-5000 300-2000 Pre~eere~
600-1500 Mo~ pre~erred

4 ~O-qO0 100-250 Preferre~
. 140-200 Mo~t ~reereed 3fl4 7-40 10-25 Preferrad 12-lB Most preferred * Trade Mark .~

~3 The amount and typ~ o organic m~dium ~vehi~le) utilized is determined m~inly by the final desired formulation viscosi~y and prin~ t~ickness.
~ arious dye6 and pigments may also be added to increase visi~ility of the p~o~o i~age. Any coloran~ used~ ho~ever, ~hould prefe~ably be t~an6parent to the actinie ~adiation used. al~hough i~ ~ay be opaque or st~on~ly absorb ot~er radiation in the vi8ible or UV spectral region.
In addition to the many parameter6 of properties and oompo~i~ion desc~ibed above, i~ i6 also es~en~ial that all of the ~omponent6 - both inorgani~ and organic - be substantially free of halogens. The reason for thi6 i~ that under normal firing conditions, halogenated ~ompounds cause cor~osion of adjoining conductive layers a6 well a6 the 6urface6 of the furnace in whi~h they are fired.
E~AMPLES
Componen~ Material 6 In the examples which are 6et out below, the following ~omponen~ material6 were used having ~he indicated properties:
A. Inor~anics Glass fri.t: Ferro (11) gla6s ~3467 ball milled in water, fractionated and dried to give a surface area ranging from 1.3 to 2.2 m2/g; compositi~n (~omponent mole %): lead oxide (5.6), ~ilicone dioxide (6~.1), boron oxide (4.7), alumina (6.5), - calcium oxide (11.1), sodium oxide (2.~ and potas~ium oxide (1.3) Alumi.na~ ~luminum oxide (A120~); particle 6ize > 0.5 ~: 90% < 5 ~;
Surface area 3-4.5 m2~g Pigment: Cobalt aluminate (CoA120~) Silicon dioxide: milled quartz; 8 mZ~g Colloidal zinc oxide ~4 Antimony pentoxide Glas~ ceramic ~. ~ric BinderG
Copolymer sf 98~
methylmethacrylate, 2%
methacrylic acid Mw ~ 25M, acid No. 9, î~herent Vi~COfiity* O.lB3 + 0.011, ~g ~ 106~C
Copolymer of 95.5~
methylme~hacryla~e, 4.5%
ethyl acrylate, Mw ~ 50M, Tg = 96C~ inherent Vl~Cosit~ 0.399 ~ 0.011 Polyisobutylmethacrylate, Mw = 60~: Tg ~ 50~C, inherent visc06ity 0.635 0.045 ~olymethylmethacryla~e, Mw = 200M; Tg . 105C, inherent visco~ity 1.252 0.115 (*) (~) Inherent visco~ity of a solution that contains 0.25 g polymer in 50 ~1 of ~ethylene chloride*
measured at 204C using a No. 5Q Cannon-~enske viscometer.
C. M nomer~
TE~TA lOi)0: Polyoxyethylated trimethylolpropane triacrylate~ 1162 Chemli~3(~)176: Ethylated pentaerythritol triacrylate (Sartomer) M~ 5 326 TMPTMA: Trimethylol propane

5,~imethacrylate (Sartomer):
Mw ~ 338 * denotes trade mark 2~
~ipentaerythritol ~w = 524 monohyd~oxypenta-acrylate (Sartomer~:
Epocryl0(~)303: Diacrylate of epichlorohydrin condensation product with bisphenol-A (Shell) De~anediol ~w 3 310 dimeth~crylate ~Sartomer~:

Pentaerythri~ol ~w ~ 298 ~riacrylate ~Sartomer):

Polyethylene Mw e 330 gly~ol 2~0 dime~hacrylate ~Sartomer):
D. Pla6ticizer6 Dibutylphthalate Dioctylphthalate Butyl benzyl phthalate Plasticizer SC: Mixture of triethylene glycol dicaprate and triethyleneglycol dicaprylate Tricre~yl phospha~e Pluronic(~) 31Rl: Block copolymer of ethylene oxide and propylene oxide Triethylene glycol diacetate E. _i iators Hichler'~ ke~one: 4,4'-bi~-N,N-dimethyl-aminobenzopherlone Ethyl Michler'~ ketone: 4,4-bi6~N,N-diethylamino-benzophenone Benzophenone Irgacure~ 651: benzil dimethylketal Iegacure~ 184~ l-hydrsxycyolohexyl phenyl ketone 2-t-butylanthraquinone ~is-(N-ethyl-1,2,3,4-tetLahydLo-6-quinolyl) ketone ~E~K~
F. O~hers Halation Protectlon Cya~orb~(5~W 24- ~,2'-dihydroxy-4-methoxy-ben20phenone Resolution and Expo~ure Latitude Improvemen~
Di-t-butylmethane nitro~o dimer Antioxidant IonolO(~: 2,6-di-t-butyl-4-methylphenol Coating Aid PolyoxO(7) WSRN-3000 Polyethylene oxide;
M~ ~ 200 preDarati~n of Dielectric Films A. PreParation of Mill Ba~e All of the cera~ic component6, gla6s feit, ~ilicon dioxide, alumina, pigment and any other inoÆqanic ~ia~erial are ~ixed with 6 g of copolymer of methylmethacrylate/methacrylic a~id (9B~) and 80.0 g methylene chloride. The mi~ture is ball milled in a half-pint (234 ~L) mill 3ar half-filled with burundum (alumina) cylinders 0.5 inch (l.Z7 cm) in both diam~ter and length for four hours. The di6per6ion i~ filtered throu~h a 32S-~e~h 6creen. The dispee6ion i6 ~tirred or 3ar~rolled until coated.
B. PreParation of Coatinq DisPer6ion The percent solid6 is determined in order to ealculate the amount of other components to be added~ After all the additional component~ ar~ in solution, exce~6 ~olvent i6 removed by ~echanically ~tirr;ng the di~per~ion in a vented area and allowing solvent to evapora~e until a vi~co~ity of 700-900 Cp~, a6 determined wi~h a Brookfield ~iBCometel, i6 ob~ainea. The di6perfiiOn i6 filte~ed through a 325-me~h 6creen.
C. Coatinq Procedure The di6per~ion i6 coated on a Talboy~ coater on 92A or 92D ~ylar~( ) tl mil (0.0025 c~)~
polyethylene terephthalate film with a 5.4 ~il doctor knife po~itioned above the ba6e which is driven at 6 ft (183 cm)/min. ~he film i8 pa~6ed through a 12 ft ~366 cm) ai~ impin~ement heater a~ 130-175F
(54-79C) before it i6 ~ound up with a polyethylene cover sheet. The thicknes~ of the coated film i~ l.B
mils (0.00~6 cm).
D Proce66 Condition6 Care i6 taken to avoid dirt contamination in the proce~6 of preparing coating composition6 and in preparing dielectric parts ~ince 6uch contamination can lead to defect6 in the fired dielectric. The proce66 work is be~t ~one ~n a cla66-100 clean room.
The film i~, laminated to degreased alumina part6 that contain a fired conductor pattern. The parts are degrea~ed ul~rasonically in chlorothene (1,1,1 ~richloroethane) and baked in a vacuum oven at 50-100C to remove the degrea~ing ~olvent. The film i~ laminated with a hot-roll laminator, ~anufactured by ~e6tern ~agnum Co., Hermosa Beach, CA with roll~
covered with neoprene havin~ a Durometer ~ating of 50 when heated to the lamination temperature of 100-110C. The fil~ i~ la~inated to the part at a ~peed of 0.5 ft (15.2 cm)/min. More than one pa6~
through the laminator can be u~ed to as~ure better adhe~ion and conformation around copper metallization6.

~8 The part6 are expo~ed with eith~c a Ber~ey-A~kor( ) vacuum printe.r or a collimated HTG (lO) W expo6ure ~ource af~er a 60-6ec nitrogen purge with the ~TG ~ource or 60-~ec drawdown in the vacuum printer in con~aot wi~h ~he photo~aryet. The optimum e~po~ure time i~ determined from an e~po~ure series that yields information on the be6t expo~ure to yield the correct ~iz~ ~ia6 or photoformed holes i~ the dielec~ric af~er de~elopment.
~he exposed part~ are developed u~i~g a 6pin developer u6ing a 6-B 6ec, 50 p6i spcay of chloro~hene developer with tbe part ~pinning at 2500 rpm, follo~ed by a 2-10 ~ec air 6tream at 50 p~i to dry the pact. The developer is ~prayed perpend;cular to the ~pinninq part. A flat-~pray 3et pattern wa~
obtained with a 0.125 in (0.318 cm) JJ air ~omizing nozzle from Spraying System6 Co., ~heato~, IL with ~etup J23 a~ de6cribed in Indu6trial Catalog Z7. The ~olvent ~low may be 50 to 2000 mL/min, p~eferably 300 mL/min. The nozzle-to-part di6tance may be 0.5 in (1.27 cm) to B in (20.35 ~m) with a typical di6tance being 1.5 in (3.81 ~m).
The developed part6 are dried in a forced draft oven a~ 75C for 15 ~in and fired in a furnace with peak temperature of 900C over a two-hour cycle. In firing the COmpOBitiOn of the invention, they are expo~ed to a ~ub6tantially nonoxidizing atmo6phere up to the gla~ transition temperature of the inorganic bindec and to an e~sentially co~pletely nonoxidizing at~o~phere durinq the ~intering pha~e of the firing ~tep.
By the term "6ub6tantially nonoxidizing atmo~phere" is meant an atmo~phere which contain6 in~ufficient oxygen to effect any significant oxidation of copper metal, but w~lich neverthele~

..~

4 ~ L' contain6 6ufficient oxygen to effect ox dation ok the organic material~ In prac~ice, it ha6 been found tha~ a nitroqen atmD~phere of 10~-1000 ppm 0~ i8 appropriate in the pre~intering pha~e of the firin7 5 step. From 300 to 800 ppm 2 is preferred. The amount of oxygen i~ increased a6 the thickne6~ of the dielectric layer increase~. ~or one layer of dielectric ilm that fires out to 25 ~m, 300 to 400 ppm 2 is ~ufficient. For two layers of dielec~ri~
film that fire~ out to 50 ~, 600 to 800 ppm 2 is preferred. On the other hand, the e~entially compl0tely nonoxidizîng a~mosphere u6ed during the gla6s sintering ~tep of the firing step refer~ to a nitrogen atmosphere con~aining only re6idual amount6 of O~, e.g., about 10 ppm. It i6 preferred to fire the compo6ition of the invention at low heating rate~
in order to minimiæe phy6ical defects in the fired layer.
The fired part6 are te~ted for helmeticity by deter~ining the wet di66ipation ~actor (DF) by application of water on top of capaci~ors made therefrom. The capacitance in picofarads (PF) i6 ~easured and ~he ~elative dielectric con~tant i6 calculated. ~he capacitor& are compri~ed of an underlying copper metallization, 40-50 ~m thick fired dielectric, and an overlying copper ~etallization.
The 50 ~m thick fired dielectric can be obtained either by firing one film to a 25 ~m thick dielectric layer and repeatinq the procedure or by ~ofiring two layer6 of dielectric film. A top layer fil~ optimized for le~ light ab60rption than the bottom layer can be u6ed ~o that adequate light penetration through the bottom layer is obtained.
Thi6 allows formation of vias with vertical 3~
~idewall~0 Alterna~ively, the first layer of dielectric can be exp~6ed but not devel~ped before the æecond layer i~ laminated ~hereonr Then, after the 6econd layer i~ lamiaated and expo6e~, both layers are developed 6imultaneou61y~
E. Te6t Procedure~
A capacitor i6 ~ormed from the above de~cribed dielectric fil~ compri~ing a copper disk having an area of 1 cm2 and a contact tab supported on an alumina ~ub6t~ate. Overlying the copper di~k i6 a layer of ~he dielect~ic film and overlying the dielectzic layer i~ a 6econd copper di6k of the 6ame ~ize having a contact ~ab rota~ed 90-180 ~ith re~pect to ~he lower tab.
Capacitance and dis~ipation factors are ~easured at 1 kHz u~îng a He~lett-Packard HP4~74A
~ulti frequen~y LCR ~eter, while insulation re~i6tance 16 mea~ured u~ing a Super ~egGhm ~eter Model R~ 17~ (8iddle In~truments. AV0, L~d., U.K.).
In~ulation refii6tance measurement6 are made after charging ttle capacitor to 100 VDC. Each number i~
the averaSIe of at lea6t 10 mea~urement6. The thickneE6 of the dielectric layer i8 ~e~sured u6ing a Gould Surfanalyzer 150~recorder 250. The dielectric con6tant i 6 calculated u6ing the equation:
K ~ A t, wherein C i6 the capacitance of the capacitor:
A i6 the area of ~mall el~ctrode in contact with the dielectric layer; and t i8 the thickne6s of the dielectric ` layer.
All capacitor~ were aged for at lea~t 15 hour6 after firing before making the electrical mea~urement6. Tt il; common that the dis6ipation ~;~ 9~
~ 1 facto~ ~DF) decrea~e6 by 0.5-2~ with;n thi~ aging time period. However, capacitance i6 generally unaffected during thi~ per~od.
Di~ipaeion Pactor on a we~ ba6i6 is determined by placing a drop of water on the upper copper di~ 60 t~at i~ we~ the di6k but not ~he ~ontact tab. After ~tanding for 30 6econd~, DF i~
determined in ~he uual manner. The dielec~rî~ i6 ~onsidered to be hermetic when the wet DF i8 le~
than 1%. Below 0.5% i8 preferLed.
ExamPle6 1-4 V6ing the above-de6cribed componen~ and procedure~ four different photo~en~iti~e diele~tric film~ ~ere prepared having ~he compo6i~ion6 indiea~ed in Table ~ below:
Table 1 Prepara~ion o Dielectric Film~ -ComPosition - Gla66/Alumina Ratio ExamPle ~o 1 2 3 4 Mill Ba6e q Gla6s frit (surface 75.00 77.83 78.70 231.43 2.06 ~2/9) Alumina (~urface area 50.00 47.i7 46.30 128.57 3 4 M2/g) Cobalt aluminate0.12 0.120.12 0.34 Copolymer oP 98/2 6.00 6.00 6.00 17.30 methylmethacryla~e/
methacrylic acid (M
25M~ T~ 105C, 30 aci~ No. 9) ~ethylene ~hloride 00.0~0.080.0 230.5 ~las6~Alumina (by wt.) 1.5 1.651.7 1.8 Table 1 (continuedl g Added ~o Disper6ion/%
D~ r~ion B~ Wei~ht of Solid~__ __ Glas~--/44.45 --/46.14 --/46.66 --/47.64 rit Alumina~-~29.64--/27.g6-~J27.~4 --~26.46 Cobalt--/0.07 --/0.07 --/0.07 --/0.07 alumina~e Cupoly- 15.93/13.43 5.63/12.~3 15.90/13.43 11.96/13.43 10 mer in dispersions Dibutyl- 9.28/5.753.65/5.759.26/5.75 6.97/5.75 phthala~e Polyoxy- --3.6~/5.75 -- -~thylated trimethylol propane tria~rylate Mw ~ 1162 Ethylated 9.28/5.75 --9.26~5.75 6.97/5.75 pen~aery-20 thritol triacrylate Benzo-1.21/0.75 0.47/0.75 1.21/0.75 0.91/0.75 phenone ~i~hler's t).08/0.05 0.03/0.05 0.08/0.05 t).06/0.05 ketone di-t-0.16/0.10 0.06/0.10 0.16/0.10 0.12/0.10 butyl-nitro~o methane dimer 30 BenZyl -- 0.63/1.0 dimethyl ketal g Disper-fiion19g.06 77.57 199.37 150.12 SolidB62n9963.56 62.81 62.78 3~

The film from Example 4 wa6 fabricated into capacitors by building up ~wo layer~ of dielectric fired 6eparately atop a copper ~onductive metallization. Upon completisn of the two dielectric layer6, an upper conductor ~etallization wa~ printed thereon a~d firea. Proce6~ c~ondition~ usea or the fabrication procedure were a6 follow6:
Lamination: 2 pa~se~ through rolls ~ 100-110C
ExpG6ure: 1 min with 2 XW mercury lamp in a Berkey-Askor 24" ~ 28" (61.0 cm x 71.1 cm) vacuum printe~ di~ance from lamp to vacuum frame 20 in (50.8 cm).
Spin developer: l,l,l-trichloroethane ~prayed on part spinning at 2500 rev/min for 6 sec followed by a 2 ~e~ air ~t~eam foE
dryin9 Oven drying: 75C for 15 min Firing: N2 belt furnase with le6~ than 1000 PP~ 2: peak temperature 900C, 2.7 hour cycle. Ga~ flow wa6 315 ft3/hr. (~.9 i~3/hr.~
The fired film from Example6 1-4 had no apparent defect~ but the film from Example 1 wa~
noticeably porous. Application of an ink ~olution (Ranger rubber stamp non6mear ink) 6howed conciderable ab&orption into the fired dielectric that would not wa6h off. In compari~on, the fired dielectric of Example 2 had only a trace of ink ab~orption and that of Example~ 3 and 4 had none.
Even though the above-de6cribed capacitor6 were fired without any apparent defect~, the ~ capacitors ~f Example 1 were nonhermetic and tho6e of - Example 2 were borderline in their hermeticity.
However, the capacitor~ of Example6 3 and 4 had quite ~ood hecmetic propertie6. In particular, the capacitor~ of Example 4 had wet DF of 0-0.5% with a rela~ive dielect~ic constant (~) of 8Ø

~ ilms fr3m all of ~he example6 were exposed through a via resolution photomask under ~he condition~ de~cribed above. When they were developed also a~ de~cribed above, they produced image6 with ~ell re601ved 4 ~il via6.
Examsle 5 A further dielec~ri~ ~ilm 6imilar to those of Example~ 1-4 was prepared i~ which a ~mall amount of quartz was added to the mill ba6e to rai~e the ~ofteninq poin~ of the ~las~ frit. The relevant compo~itions of the film are given in Table 2 below:
Table 2 Propertie~ of Dielectri~ Film~ -Compo6ition - Ouartz Addition Example No. s _ ~ill Ba~e q Gla~ frit of Example6 l-4 78.78 Alumina of Example6 1-4 43.77 Cobalt ~luminate 0.12 Milled ~auartz, surface area ~ m2/g 2.45 Copolymer of Example~ 1-4 6.00 ~ethylene chloride 80.00 Gla6s/Alumina (by wt.) 1.8 DiGpet~ion Gla~6 frit --/46.70 Alumina --~25.95 ~obalt aluminate --~0.07 Quartz --/1.45 Copolyme~ in di6per6ion615.92/13.~3 Dibutylphthalate 9.27/5.75 Ethylated pentaerythritol9.27/5.75 triacryla~e ~enzophenone l.Zl/0.75 Hichler'~ ~etone 0.08~0.05 Di-t-butylnierofiomethane 0.16/0.10 dimer g Di~persion 199.04 % Solid~ 62.91 2~ Process conditions were the 6ame a6 for Example6 1-4. The fired part~ were free of defects.
The film of Example 5 wa6 found to retard the tendency of bli6ters to occur in the overlying conductor layer upon multiple firing. Thi6 i6 attributed to the higher 60ftening point of the quartz-doped frit which reduce~ the tendency of the glas6 to migrate into the conductor layer.
~xamPle~ 6-B
Three further photosensitive dielectric films were made in which different ~nono~er6 were u~ed. The relevant compo6ition6 of the films are given in Table 3 below:

~.2~i~5~'~

Table 3 Prepara~iGn of Dielec~ric Films -ompo~ition - ?Sonomer Variatiorls Exam~le No. 6 7 ~ _ lMill Ba~e _ q Gla6~ frit of Example~ 1-4236.00231.~3 231~43 Alumina of Examples 1--412~ . 20128 . 57 128 . 57 Cobalt alu~inate -- 0 . 34 0 . 34 Copolymer of Examples 1-417 . 3017 . 30 17 . 30 l~ethylene clhloride230.53231.50231.50 Glas6/P.lumina (by wt. ) 1.9 l.B 1.8 lS

:~0~

T~ble 3 (continued~
g Added to Di~per6ion~
Di6pe~6ion~Y Wei~ht of Solid6 _ Glass frit --/4B.65 ~-~47.64--~47.84 Alumina --/25.60 --~26.46-/2~.4 Cobalt aluminate -- --/0.07 --/0.07 Copolymer of 2.93fl2.~9 4.22/13.4 4.96/13.43 Example6 1-4 10 p0lyoxyeehylated l.B9/5.75 trimethylolpropane triacrylate ~w ~ 1162 Dipentaerythritol -- 2.46/5.~5 --monohydroxy pentaacrylate Diacrylate of -- -- 2.89/5.75 condensation product of epîchlorohydrin and bi~phenol-A
1 10-decanediol- 1.89/5.76 -- --dimethacrylate Dibutylp~thalate -- 2.46~5.7S 2.B9/5.75 Benzophenone 0.49/1.5 0.32/0.75 0.38/0.75 Michler'~ ~etone -- 0.02/0.05 0.04/0.05 ETQX 0.02/0.05 -- --Cya~orb W 24 0.03/0.1 -- --Di-t-butylnitro~o- 0.03/0.1 0.04/0.10 0.05/0.10 methane dimer g Disper~ion 40.61 55.77 49.94 t Solid6 62.82 72.00 72.00 The proce66ing condition for the above film6 were the ~ame a~ for Example6 1-4 and all of the fired compo~ition~ hacl no significant defect6.
* denotes trade mark ~: am~le 9 In thi6 example~ 3 dielectric f ilm wa~ made in which two polyme~ic binder6 ~ere u6ed. The relevant compo6i~ion6 o~ the f ilm are given in Table 5 4 below:
Table 4 Properties of Dieleo~ric Filr~ -Compo~ition - Dual Binders xample No. 9 ~ill Base q_ GlasB f rit of Example6 1-47B.78 Alumina of Example~ 1-443 . 77 5ilicone dioxide ~qua~tz of2.~5 Example 5 ~
Cobalt aluminate 0.12 Copolymer of E:xample~ 1-46 . 00 l!fethylene chloride 80.00 Gla~/Alumi~a (by ~t . ) 1. 8 5~

3g T~ble_~_L~ E~
Di6per~ion Gla6~ frit --~46.70 Silicone dioxide ~ 5 Alumi~a -~/25.95 Cobalt aluminate --J0.07 Copolymer of Example6 1-412.47/11.05 10 Copolymer of 95.5~ methyl3.63/2.18 me~hacrylate 4.5~ ethyl acrylate Mw = 50M, Tg 96~C
Dibutylphthalate 9.57~5.75 Polyoxyethylated tr;methylolpropane 9.57/5.75 triacrylate Ben~ophenone 1.25~0.75 Michler'6 ketone O.OB/0.05 Di-t-bu~ylnitro60methane dimer0.17~0.1 20 2,6-di-t-butyl-4-methylphenol 0.33/0.20 g Disper~lon 201.11 ~ Solids 64.31 The film wa6 proce6sed a6 described in Example~ 1-4 and yielded fired dielectric~ having a wet DF of 0.12+0.09 for 10 capacitor6 and no 6ignificant defect6.
Example6 10 and 11 Two further film compo6i~ion~ were prepared in which the top dielec~ric layer Gomposition WaB
ad~u~ted to provide Eor lower light absorption and to allow more light penetration through to the underlying dielectric layer. The organic content wa6 al60 reduced to give better fireability. The ~o relevant compo~i~ions of the f ilm are given in Ta~le 5 belo~7. The di6persion for Example~ 10 and 11 was ~btained f rom the mill ba~e de6cribed below.
Table 5 Preparation of Dielectric Film~ -Composition Li~ht Ab~orption and ~ireability Component q5 Glas frit of Example~ 1-4 236.00 Alumina of Examples 1-4 124 . 20 Copolymer o~ Example6 1-4 17 . 30 ~5ethylene chloride 230 . 53 Gla6s~Alumina (by wt. ) 1.9 Table 5 ~con~inued~
E~amPle No. 10 11 g Added to Di~per~ion/~
Di6Pe~6ion ~ eiqht of 501id~ _ Glas~ frit --~52.41 -/48.55 Alumina --i27 ~ 5g -/Z5 . 55 Copolymer of 11.12/9.42 19.53/12,68 Example6 l- 4 Dibutylphthalate10.92/5.~812.27/5.74 Tri~ethylolpropane 7.97/4.00 triacrylate Polyo~yethylated - 12. 27/5 . 74 trimethylol propane triacrylate Benzyl dimethylketal 1.99/1.00 Benzophenone 3.21/1.5 Bis-(N-ethyl-1~2.3,4- O.ll~O.Q5 tetrahydro-6-quinolyl) ketone Di-t-butylnitro~o-0.20/0.10 0.21/0.10 ~ethane dimer 2,2'-dihydroxy-4- 0.21/0.10 methoxybenzophenone g Di6p~r~ion Z65.6Z 265.~5 % solid6 62.91 62.44 The film of Example 10 wa~ laminated to the bottom layer film of Example 11. A~ with the bottom layer, the top layer wa~ laminated with two pas6e6 through the laminator. Except that both layer6 were imaged, developed and fired together, the film wa6 procefi~ed as for Example~ to yield a 38 ~m thick dielec~lic. Re-lative dielectric ~on6tant wa6 8.0, t DF 5 0.1. The top layer film wa~ 1.3 mil~ and the bottom laye~ film wa~ 1.5 mil~ thick. There were no 6ignifican~ defect~.
Example 12 ~n additional film compo~ition wa~ p~epared in which ~he gla~ frit and alumina were ~urface pretreated with a 6ilane coupling agent and a polymeric binder without acidic functionality wa~
ufied. The gla~6 frit and alumina are sepalately treated in 2 kg quantitie6 in a Patterson-~elley twin-shell V blender with ~he silane coupling agent pre6~ure-f~d over 10 min. as a 4~ solution in 95%
ethanDl containing a trace of glacial acetic acidO
The sample was mixed for 10 additional ~inutes with lS the inten6ifier bar in ~otion during the entire mixing. The sample ~a~ dried 1 hour at 105~C. The organic level was reduced to give better fireability. The disper~ion compo6ition is given in Table 6 below.
Table 6 PrePa~ation of Dielectric Film Mill Ba6e Gla66 frit of Example~ 1-4 6urface 215.43 g pretreated with 0.5 wt. t of y-methacryloxypropyl-trimethcxysilane Alumina of Examples 1-4 surface lls.68 pretreated as the glas6 ~rit Cobalt aluminate 0.32 Copolymer of 95.5% meth~lme~hacL~late 16.10 4.5t ethyl acrylate, Mw ~ 50M.
Tg e 96~C
Methylene chloride 214.5 Glas6/alumina (by wt.) 1.8 * denotes trade mark ~3 g Added to Disper~ion~
By Weiqht of Di6Per6ion s9lid~ _ Gla~s frit --/50.07 Alumi~a --/27.~1 Cobalt Aluminate --~0.06 Copolymer of mill ba6e6.06/10.49 Polyoxyethylated trimethylol 3.53/3.93 propane triacrylate Dibutyl phthalate2.95/3.28 Benzyl i~ooctyl phthalate 2.94/3.27 ~ichler 1 6 ke~one0.04/0.04 Benzophenone 0.5B/0.64 Di-t-butylnitro~ome~hane dimer 0.08/0.~9 Ionol~(6) 0.15/0.17 Polyethylene oxide, Mw = 200M 0.14/0.15 g Di6per6ion li6.39 t Solid~ 63.05 The film wa6 proce66ed as de6cribed in Examples 1-4 except that two piece6 of film were p~elaminated together at 1 ft/min (30.5 cm/min). One of the coYer sheets wa6 removed and the compo~ite ~a6 laminated at 0.5 ft/min (15.2 cm/min) to the test 6ub6trate. The excess film wa~ cut away ~nd the part ~a6 pa~sed two times throuqh a laminator wlth ~he orienta~ion changed laO after the first pa~6 to a66ure good adhesion and conformation around elevated conductor feature~. The part was exposed for 20 ~4 ~econd6 with a HTG 60urce at 16 mW/cm2 and spin de~eloped for 14 ~econds in chlorothene. The developed pare ~as baked 15 minute6 at 75~C followed by 1 hou~ at 250C. The part was fired u~ing a two-hour cy~le at 1.7 in/min (4.32 cm/min) in an 8-zone belt furnace with the oxygen concentration reaching a maximum of 500 ppm and a peak temperature of 900~C. Capacitor6 prepared a~ described above vere 50 ~m in thickne6s and had a dielectric con~tant of 6.7 and wet DF of 0.5 and had no significant defect~.
ExamDle 13 An additional film compo6ition utilizing a polymeric binder having a ba~ic component wa6 prepared a~ given in Table 7:
Table 7 Disper~ion Containinq Ba~ic Polymeric Binder Mill ~a~e g Gla6s frit of Example6 1-4 with75.00 1 wt. % ~urface treatment with ~-methacryloxypropyl trimethoxy ~ilane Alumina of Example6 1-~ ~urface50.00 pretreated as the glas~ frit Cobalt aluminate 0.10 Terpolymer of ethylmethacrylate/methyl 19.91 acrylate/diethylamino ethyl-methacrylate 62.3/37.1/0.6 Mw D 127~:
Mn ~ 77M; 30.32% ~olids in ~ethyl - ethyl ketone 3~
Methylene chloride ~0.0 GlassJalumina (by wt.) l.S0 ~5 ~5 g Added to Di~per~ion/%
By ~eight of Di6per6ion Solid~ _ Gla~6 frit --/46.73 Alumina --/31.15 Cobalt ~luminate --~0.06 Terpolymer of mill ba6e--/3.~4 Copolymer o Example 125.37/7.49 Polyoxyethylated trimethylol 8.49/4.87 propane triacrylate Dibutyl phthalate3.49/~.~7 ~ichler'~ ketone0.03/0.04 Benzophenone 0.46/0.64 Di-t-butylnitro60methane dimer 0~0~/0.09 IonolO(~j 0.12/0.17 Polyethylene oxide, ~w ~ 300M 0.11/0.15 g Dispersion 100;69 % Solid~; 58.12 The film wa6 proce6sed as des~ribed for Example 12 1:o yield defect-free dielectric.
ExamDle 14 An additional ilm compo6ition wa~ prepared in which the gla66 frit and alumina were 6urface pretreated with a polypropylene oxide-containing organo~ilane e~ter in ~he 6ame manner ~ Example 1~.
Thi6 i6 deemed to be the be~t mode of p~acticinq the in~ention. The di~per6ion compo~ition i6 given in Table 8 below.

.~

9~f~
~5 'rabl e_8 P~
~ill Ba~e ~ .
Gla6~ frit of Example 1-4 with1844.0 0.5 ~t. % surface treatment with Union Carbi~e Yg883(1~), a polypropylene oxide containin~
organo6ilane ~ter Alumina of Example~ 1-4 ~ith 0.5 ~t. % 1418.0 Y98~3 Cobalt Aluminate 3.08 Copolymer of Example 12 156.6 Methylene Chloride lB27 g Added to Disper6ion/~
Di6Per6ionBy_Weight of Solid6 _ Gla~6 Frlt -- /44.02 Alumina -- /33.B6 20 Cobalt Aluminate -- / 0.07 Copolymer of Mill i3a~e251.6/10.48 Polyoxyethylated Trimethylol- 146.7J3.93 propane Triacrylate 25 ~ibutyl Phthalate122.4t3.28 ~enzyl I~ooctyl Phthalate 122.1~3.27 Michler' 6 ~etone1.5/0.04 Benzophenone 23.9~0~64 30 Di-t-butylnitro~omethane Dimer 3.4/0~09 Ionol0(~) 6.3/0.17 Polyethylene Oxide, ~w - 200M 5.6/0.15 g Di6per6ion 4676.5 35 ~ Solid6 . 65.2 ~6 ....

~7 The di~pel~ion wa~ jar rolled at 32 revolution~ pe~ minute fol 4 hour~ in a 2.3 gal (a~7 1) mill jar ~on~aining 19.5 lb6. (8.B ~g~ of 0.5 in (1~27 cm) burundum cylinders. The re6t of the film component~ were added af~er the ~ 601id~ of ~he di~per6ion was determined. The di~peE~ion wa6 6tirrea ~echanically overnight and then 1 hr.
~agnetically with ~ild agi~ation to remove air from the di~persion. The di~per6ion % solidfi wa~ 70.4~
and the viscosity wa~ 680 centipoi6e a6 mea6ured with a Brookfield vi~cometer (No. 6 6pindle at 50 rpm).
~he di~persion was filtered through a 20 ~icron polypropylene filter and extru~ion die-coated ~o a thickne~s o~ 1.75 ~il6 (0.044 mm) on 1 ~il (0.0025 ~m) sili~one-treated polyethylene terephthalate.
This coating wafi then laminated to a second coating of the same di6per6ion coated a~ above on 0.5 mil ~0.00125 cm) polyethylene terephthalate. The lamination pres~ure wa~ 11 to 12 p6i (0.77 to 0.84 kg/cm2). The coa~ing6 before lamination were dried in three 8 t. (2.44 ~) long dryer zone~ with the l~t zone at 120P (48.9C), the 2nd zone at 140F (60C) and the 3rd zone at 200~F (93.3C).
The film wa6 proce66ed in the ~a~e manner a6 Example 12 except that the dielectrit~ film wa6 laminated direc~ly to the te6t sub6tra~e. After the laminate was cooled to room temperature, the cover sheet wa6 pulled off, removinq the exces6 film from the edge6 of the part. The part was baked or 10 min in an 105C convection oven and, after a N2 purtJe, expo6ed to actinic light through a photomask which wa6 ~lightly removed f~om the photopolymer surface.
Expo6ure was carried out for Z0 6ec with a ~TG sourte at 16 mW/cm2 and then 6pin developed for 12 sec in l,l,l-trichloroethane. The developed part wa~

~7 .. .

q0 b~ked f or lS min at 75C 2nd f ired as Exam~le 12 to yield a dielec~Lric layer ~f 50 mic~ons with well ~e601ved 12 ~ 304 . fl ~icron) via~ . The resulting diele~ric coating had no ~ignifi~ant defeet~.

1~

~5 .

) Tzademark of Sartomer Co., We~t Che~ter, PA, for acrylate mvnomer~.
5 ~2) Trademark of Shell Chemical Co.O Houston, T~t for epoxy re~in ~crylate6.
(~) Trademark of BASF-Wyando~te, ~yandotte, MI
for nonioni~ ~urface active agent~.
(~) Trademark of Ciba-Geigy Corp., Yard61ey, NY
for ~uring agen~6 activated by ultraviolet light.
(5) Trademark of American Cyanamid Corp., Bound Brook, NJ for light stabilizer6.

(~) Trademark of Shell Chemical Co., Hou~ton, TX
for hindered phenolic antioxidant~.

(~ Tr~de~ark of Union Car^Dide Corp., ~orriztown, NJ for water-~oluble ethylene oxide polymer re6in6.
(-~ Trademark of E. I. du Pont de Nemour6 and Company, Inc., for polyefiter fil~.
(a) Beckey Technical Div., Berkey Photo Inc., Wood~ide, NJ.
(~~ The Hybrid Technology Group Inc.s San Joe, CA.
25 (~ rademark of Ferro CorpDration, Cleveland, OH for glas~ f~it.
(12) Tcadename of Union Calbide Corp., Morrifitown, NJ for poly(propylene oxide)-containing organosilane ester.

Claims (11)

1. A photosensitive ceramic coating composition which is fireable in a substantially nonoxidizing atmosphere comprising an admixture of:
(a) finely divided particles of ceramic solids having a surface area-to-weight ratio of no more than 10 m2/g and at least 75 wt. % of the particles having a size of 1-10 µm, and (b) finely divided particles of an inorganic binder having a glass transition temperature of 550-825°C. a surface area-to-weight ratio of no more than 10 m2/g and at least 95 wt. % of the particles having a size of 1-10 µm, the weight ratio of (b) to (a) being 0.6-2, dispersed in an organic medium comprising (c) an organic polymeric binder selected from the group consisting of (1) homopolymer and copolymers of C1-10 alkyl acrylates, C1-10 alkyl methacrylates, alpha-methylstyrene and 0-2 wt. % ethylenically unsaturated carboxylic acid, amine or silane-containing compounds, (2) homopolymers and copolymers of C1-10 mono-olefins, and (3) homopolymers and copolymers of C1-4 alkylene oxide and mixtures thereof, the binder comprising 5-25 wt. % basis total inorganic solids, and (d) a photoinitiation system, dissolved in (e) photohardenable monomer, and (f) an organic medium.

2. The composition of claim 1 in which the organic medium is comprised of volatile nonaqueous solvents.

3. The composition of claim 1 in which the organic polymeric binder is a copolymer of 95.5 wt. %
methylmethacrylate and 4.5 wt. % ethyl acrylate.

4. The composition of claim 1 in which the photohardenable monomer is poly(oxyethylated trimethylolpropane triacrylate).

5. The composition of claim 1 in which the ceramic solid and inorganic binder have been surface treated with an organosilane ester coupling agent.

6. A photosensitive ceramic film comprising a layer of the composition of claim 2 from which the nonaqueous organic solvent has been removed by volatilization.

7. A patterned ceramic layer comprising the film of claim 3 which has been (1) laminated to a ceramic substrate, (2) exposed imagewise to actinic radiation to effect hardening of the exposed areas of the film, (3) solvent developed to remove unexposed areas of the film, and (4) fired in a substantially nonoxidizing atmosphere to effect volatilization of the organic medium and sintering of the inorganic binder and the ceramic solids.

8. The composition of claim 1 which is a paste in which the organic medium is comprised of solvents having an atmospheric boiling range of 130-350°C.

9. A multilayer capacitor comprising a substrate, a first conductor layer overlying the conductor and at least one set of alternating layers of (a) the composition of claim 1 overlying the conductor layer and (b) an overlying conductor layer, the layers of the assemblage having been fired to effect volatilization of the organic component of the layers and to effect sintering of the inorganic binder.

10. The capacitor of claim 6 in which each of the layers was fired individually after application to the underlying layer and before application of the overlying layer.

11. The composition of claim 6 in which the layers were cofired.