CA1274385A

CA1274385A - Thin tape for dielectric materials

Info

Publication number: CA1274385A
Application number: CA000515186A
Authority: CA
Inventors: Issam A. Khoury; Robert H. Ii Heistand; Iwao Kohatsu
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1985-08-02
Filing date: 1986-08-01
Publication date: 1990-09-25
Anticipated expiration: 2007-09-25
Also published as: IL79520A0; US4752857A; KR870002621A; JPS6236062A; MY100596A; EP0210874B1; IL79520A; US4641221A; EP0210874A1; DE3669612D1

Abstract

ABSTRACT

An improved, flexible, strong, thin precursor green tape for dielectric ceramics is described. The tape is prepared from a cellulosic resin of specific characteristics. The tape is especially useful in the preparation of multilayer capacitors and related electronic devices.
32,773A-F

Description

s THIN TAPE FOR
DIELECTRIC MATERIALS

The present invention is directed to cer~
amic precursor tapes and their use in the manufacture of electronic components.

The preparation of dielectric ceramics is similar to the preparation of other ceramics in that a green, i.e., unfired, piece is first prepared and then fired to obtain a desired ceramic article.
In the preparation of multilayer capacitors, pre-formed sheets, films or strips of green, dielectric material are coated with a pattern of an electrode ink, stacked, compressed and fired to provide a monolithic multilayer capacitor. For a given dielectric material, capacitance is a function of thinness, i.e., capacitance increases as the thick-ness of a dielectric layer decreases~ Thus, it ispossible to reduce capacitor size while simulta-neously increasing the capacitance of the capaci-tor. Theoretically, there is almost no limit to 32, 773A-F

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127f~3~35 the smallness of multilayer capacitors. However, practical size limitations exist due to the nature of green tapes and the problems associated with their handling.

The physical properties of green tapes become a critical factor in the preparation of thin-ner, highe~ capaci-tance, dielectric layers. Lack of strength makes green tapes susceptible to tear-ing. Lack of flexibility leads to cracking. Thus, in the preparation of multilayer capacitors and similar devices having thinner dielectric layers, it is essential to produce a thin green tape strong enough to be free-standing and capable of maintain-ing its physical integrity throughout the processes of ink screen printing, laminating and dicing.

Tapes typically are prepared by tape--casting or knife-coating a slip onto a nonporous carrier. The slip typically contains a ceramic powder, a binder, a wetting agent, a solvent, and a plasticizer, depending on the specific applica-tion. A wide variety of materials are used as the binder. For example, Thompson, J. J., in Ceramic Bullet n, Vol. 42, pp. 480 1 (1963), discloses the use of organic binders such as methylcellulose, starch derivatives, or preferably polyvinyl alco-hol. U.S. Patent 2,736,080 discloses the use of cellulose or cellulose pulp in the production of dielectric sheets having an approximate thickness of 5 mils. U~S. Patent 2,759,854 discloses the use of high viscosity ethylcellulose and an ester gum 32,773A-F -2-.

- . : ' ' :

.

~7~35 binder in the preparation of supported green films having a thickness in the neighborhood of 3 mils or less. UK Patent 1,493,102 discloses a process for the preparation of glass microchanneled bodies by dlpping a filament into a solution of a ceramic powder and a polymeric film-former. Polyvinyl alcohol, polystyrene, ethylcellulose, cellulose nitrate, and dialkoxy poly-titanates are listed as suitable film-formers. U.S.
Patent 3,495,996 discloses the use of natural gums, s~nthetic resins, cellulose resinous materials, and the like, in the preparation of encapsulated electronic devices. U.S. Patent 3,536,508 discloses the use of binders such as solid ethylcellulose resins, solid polymers of an acrylate or methacrylate ester of a 1-4 carbon aliphatic alcohol, polyvinyl alcohol or poly-vinyl butyral for the preparation of flexible green sheets having a thickness of about 4 mils.

U.S. Patent 2,966,719 discloses the pre-paration of a green ceramic tape having a thickness as thin as on the order of 1 mil using binders such as cellulose acetate butyrate resin compatibly plasticized with dimeth~l phthalate or tricresyl phosphate, or polyacrylate esters. However, the preparation of said ta2e reguires that the tape be cast onto a flexible support. U.S. Patent 3,619,220 discloses the pre-paration of a fired ceramic having a thickness of approximately 1 mil using ethylcellulose as a binder.
However, the product is fired on a glass plate and is not taught to be free-standing.

32,773A-F -3-.
- .

. . : : -,, . . . - :' , .:. . ~ --U.S. Patent 2,486,410 discloses an early process for the preparation of flat ceramic plates using binders such as ethylcellulose. The resulting tapes are described as being "leather-hard."

U.S. PateIlt 3,189,978 diseloses a process for the preparation of multilayer circuits by first pre-parin~ a plurality of dry, thin films, each comprising finely divided ceramic particles and a heat-volatile binder therefor. Said patent discloses that a ilm having a thickness of about 1 mil is flexible and strippable from the carrier upon which it is cast. The binder is vinyl chloride-acetate copolymer. A metal--containing ink is applied to the previously described film. The metal ink is taught to contain binders such as methylcellulose, ethylcellulose, or nitrocellulose.
The patent broadly teaches that the thickness of u~fired ceramic films may be varied between 0.5 and 20 mils.

U.S. Patent 3,004,197 discloses a process of making a ceramic capacitor by forming a self--sustaining sheet comprising a ceramic material and a plastic polymer, metallizing a portion of the sheet, winding the metallized sheet into a coil and firing.
The fired, coiled dielectric is taught to have a thickness of 3 mils (about 75 microns) or less. Cel-lulosic resins are broadly taught to be useful as thefilm-forming plastic polymer.

U.S. Patent 4,447,353 discloses the pre~
paration of multilayer capacitors having individual dielectric layers of from lO to 30 microns in thick-ness. The only statement in said patent regarding the .
32,773A-F -4-- - - . - .
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` ~2743~5 64693-3877 binder is that "the manufacturing method of the multilayer capacitor is the same as the prior art method".
Heretofore~ a flexible, strong, thin, free-standing, ceramic green tape having a thickenss of less than about 25 microns (about 1 mil) has not been disclosed. Such a tape would be desirable for the preparation of improved multilayer capacitors and related devices.
Surprisingly, the present invention supplies all these above-described needs. The present invention concerns a green ceramic precursor tape which comprises a free-standing, fle~ible layer having a thickness not greater than about 25 microns and prepared from a slip composition having:
(a) a dielectric component in an amount sufficient to provide said tape with desired dielectric properties;
(b) a binder comprising alkylcellulose ether or a hydroxyalkylcellulose ether, preferably ethylcellulose, having a viscosity of 40 to 110 centipoise (measured at 25C as a 5 weight percent solution in a solvent that is 80 weight percent toluene and 2 weight percent ethanol) in an amount sufficient to bind the dielectric component into said tape upon removal of solven-t; and (c) a solvent in an amount sufficient to solubilize components (a) and (b) and to enable said tape to be formed.
The dielectric component serves to furnish the raw material, which on high temperature processing forms the ceramic body. The dielectric component is selected to provide the physical, thermal, electrical and chemical properties which are .

~27~385 6~693-3877 desired in the finished ceramic. For example, titanates, especially barium titanate, exibit a very hi~h dielectric constant; therefore, titanates are the preferred dielectrics in green tapes from which capacitors of high capacitance are prepared. The amount of dielectric component present is sufficien~ to provide the resul~ing thin film with the desired dielectric properties.

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Generally, the binder serves to retain the dielectric component in an undisrupted position after the solvent is evaporated from the slip and, together wit~ the solvent, facilitates the formation of dry, flexible green tapes which are free of pinholes, cracks and other imp~rfections. The amount of binder present is suficient to bind the dielectric material into the thin film upon removal of the solvent.

The solvent functions to solubilize all compon~nts of the slip which are volatile under ceramic firing conditions. The solvent is also useful in controlling the viscosity of the of the slip, thereby facilitating the formation of thin ilms. The amount of solvent present is sufficient to solubilize the dielectric component.

Surprisingly, the use of slip compositions as described herein, allow the production of improved free-standing, flexible, thin, green tapes having a thickness not greater than 25 microns (about 1 mil).
The present invention includes capacitors prepared using such green tapes.

According to the present iIl~ention, a slip comprising a dielectric component, a binder, a solvent, optionally a surfactant, and optionally a plasticizer, advantageously is prepared. Conventional methods of formulating or compounding this slip can be employed so long as it is -thoroughly mixed to form a homogeneous suspension. The prepared slip ma~ then be deaired by agitating the slip in a vacuum. After deairing, the slip may be filtered to remove any large pieces of 32,773A-F -6-' ' . ~ ~ :

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lX74385 64693-3877 dielectric component or undissolved binder that may be present.
Both air bubbles and large solid particles can cause defects in the cast tape or fired product.
The slip is deposited on a nonporous carrier using ]cnown methods such as, for example, the falling sheet method as taught in U. S. Patent 3,717,487, or the well-known tape-casting, doctor blade or knife-coating techniques. For example, U. S. Patents 3,189,978; 2,486,410; and 2,966,719 describe methods of casting green tapes. In general, the tape-casting technique involves applying a thin layer of a slip to a flexible or nonflexible, non-porous carrier, such as a smooth glass plate or plastic strip.
The carrier coated with the slip is passed under a doctor blade, with the gap under the blade controlling the thickness of the coating. After being spread on the carrier, the slip is dried to remove its volatile constituents. Drying is accomplished by exposing the slip to air at room temperature or by heating the slip in an oven, optionally under forced air circulation. The resulting dried film can be stripped from the carrier, thereby yielding a free-standing green tape. Thus, the above process can generally be described by applying a thin layer of a coating to a flexible or nonflexible, nonporous carrier, controlling the thickness of the coating, drying the coating/carrier, and removing the coating (green tape) from the carrier.
The dielectric component of the slip can be a dielectric powder, a material which upon firing is converted into a dielectric, or a mixture thereof. Dielectric materials are well-known, and a wide variety .
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~, of dielectric materials can be employed. Examples of dielectric powders lnclude powders consisting mainly of alumina, zircon, aluminum silicate, magnesium aluminum silicate, aluminum nitride, beryllia, zirconium dioxide, titanium dioxide, magnesium silicate, and, prefer~bly, barium titanate. Typically, the ceramic component is ground to a fine particle size ranging from 0.05 to 5 microns. Preferably, dielectric powders having an average particle size of from 0.5 to 2 microns are employed. Preferably, the dielectric component con-stitutes greater than 75 percent by weight of the slip composition, excluding the weight of the solvent.

The binder may be any one or a combination of cellulosic resins. Cellulosic resins are derived from and have the polymeric "backbone" of cellulose, which is a naturally occurring polymer. Cellulose has a structure of repeating anhydroglucose units, each unit of which contains three hydroxyl sites. Reactions at the hydroxyl sites yield derivatives generally clas sified as cellulo~ic resins. For example, esterifying the hydroxyl groups produces cellulose ethers. Pre-ferred binders include cellulose nitrates, cellulose esters, alkyl cellulose ethers, hydroxyalkylcellulose ethers, alkyl hydro~ylalkylcellulose ethers and dialkyl-ene glycol cellulose ethers. More preferred ~indersinclude alkylcellulose ethers and hydroxyalkylcellulose ethers. The most prefexred binders lnclude ethylcel~
lulose, 2-hydroxyethylcellulose, and thermoplastic methylcellulose. Thermoplastic methylcellulose is prepared according to the methods described in U.S.
Patents 3,070,451; 2,965,508; 2~958,607; 2,849,328, and

2,839,419. Preferred ethylcellulose bindeFs have a ;

32,773A-F -8 - . . - -:

' ' . ' ' ': ' ' ' ~ ~7a~3~3s ._g_ , viscosity greater than about 40 centipoise. Green tapes cf less ~han 25 microns thickness maintain their s-tructural integrity when prepared from ethylcellulose binders having a viscosity of grea-ter than about 40 centipoise; whereas tapes of this thinness with lower viscosity ethylcellulose binders tend to crack. More preferred ethylcellulose binders have a viscosity from 40 to 110 centipoise, the viscosity being that of a 5 weight percent solution measured at 25C ln an Ubbelohde viscometer with a solvent which is 80 weight percent toluene and 20 weight percent ethanol. Pre-ferred ethylcellulose binders are ethylcellulose having an ethoxyl content of from 44 to 53 weight percent.
More preferred ethylcellulose binders are ethyl-cellulose having an ethoxyl content of from 47.4 t.o49.5 weight percent. The most preferred ethylcellulose binder is an ethylcellulose having an ethoxyl content of from 48 to 49.5 weight percent. Mixtures of binders can be employed. Premium standard ETHOCEL~ 45 and ETHOCEL~ 100 (ETHOCEL is a trademark of The Dow Chemical Company~ brand ethylcellulose are the most preferxed binders, as they have a low sodium chloride content and meet the reguirements specified here-inabove; ETHOCEL~ 45 and RTHOCEL~ 100 are avail~ble from The Dow Chemical Company. Premium standard ETHOCEL~ 45 has an ethoxyl content of 48.0 to 49.5 weight percent and a viscosity range of 41 to 49 centipoise, measured as described herein above. Pre-mium standard ETHOCEL~ 100 has an ethoxyl con-tent of 48.0 to 49.5 weight percent and a viscosity range of 90 to 110 centipoise, measured as described above. Other ETHOCEL~ binders which can be used are: ETHOCEL~ 7 which has an ethoxyl content of 48.0 to 4g.5 weight percent 32,773A-F -9-- ' .. , ' - ' ' ' .

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and a viscosity range of 6 to 8 centipoise; ETHOCEL~ 20 - which has an ethoxyl content of 48.0 to 49.5 weight percent and a viscosity range of 1~ to 22 centipoise;
ET~OCEL~ 20G which has an ethoxyl content of 48.0 to 49.5 weight percent and a viscosity range of }~0 to 220 centipoise. The viscosity was described above.

The ethylcellulose binders are chosen because of their toughness and unusual degree of flexibility.
They have good suspending properties for the highly dense dielectric powder. The presence of some hydroxyl groups on the cellulose backbone increases the inter~
action and dispersion of the metal oxide in the vehicle.
Moreover, the permeability of cellulose ethers to 2' C2 and ~2 are orders of magnitude higher than acryl-ates allowing proper diffusion of gases upon burnout oxfiring.

The solvent may be any substance or com-bination of substances which solubilize the components of the slip which are volatile under ceramic firing conditions. Preferred solvents include alcohols, ketones, aromatic compounds and halogena~e~ compounds.
More preferred solvents include toluene, ethanol, butanol, acetone, methylisobutyl ketone, methyl ethyl ketone, isopropanol, l,l,l-trichloroethane and benzene.
Mixtures of solvents, such as mixtures of methyl ethyl ketone and ethanol, are most preferred. Water can be employed as the solvent when thermoplastic methylcellu lose is employed as the binder.

32,773A F -10-.
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~.~7~38~i A wetting agent, or surfactant, is optionally employed in the slip composition. The surfactant facilitates the formation of homogeneously uniform slips having desirable spreadability. Surfac-tants are well-known and a wide variety of surfactants can be employed. Examples of typical wetting agents or sur factants include the amine salts of alkylaryl sul-fonates; the alkyl ethers of polyethylene glycol, such as the ethyl ether of polyethylene glycol; alkylaryl polyether alcohols, such as èthylphenyl glycol; poly-oxyethylene acetate, or other polyoxyethylene esters.
The surfactant or wetting agent preferably is of such a nature that it is volatilized during firing.

A plasticizer is op-tionally employed in the slip composition. Plasticizers are well-~nown and a wide range of plasticizers can be employed. Examples of typical plasticizers include mineral oil; glycols, such as propylene glycol; phthalic esters such as dioctyl phthalate and benzyl butyl phthalate; and long chain aliphatic acids such as oleic acid and stearic acid; and mixtures thereof. The plasticizer serves to enhance the film-forming characteristics of the slip, and to impart flexibility into the green tape at lower temperatures. Preferably, more than one plasticizer is employed. For example, a preferred plasticizer mixture comprises benzyl butyl phthalate, propylene glycol, and oleic acid.

A typical slip composition can have the following ranges of components, in weight percent:

32,773A-F

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dielectric component from 25 to 94;
binder from 0.6 to 33;
solvent rom 4 to 66;
surfactant from abou-t 0 to 11; and plasticizer from about 0 to 20.

More preferred slip compositions have the following ranges of components, in weight percent:

dielectric component from 32 to 78;
binder from 1 to 20;
solvent from 16 to 58;
surfactant from about 0 to 2; and plasticizer from 0.6 to 11.

Preferred slip compositions have relatively higher amounts of ceramic powders with relatively lower amounts of organic binders and solvent. However, a green tape needs a certain minimum amount of organic binder to maintain a mechanical strength as a free -standing tape, and a slip typically has a minimal amount of solvent to retain the rheological properties for tape-casting. Said properties include the vis-cosity of the slip and the flow characteristics of the slip under the shear and stress forces of the doc-tor blade.

Desirably, the slip of the present in~ention is formulated to have a viscosity which is suitable for the chosen method of applying the slip to a carrier.
For example, typical slip compositions used in tape--casting have a viscosity of from 400 to 3,000 cps at 32,773A-F

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~7~3~35 25C as measured in a Brookfield viscometer. Slips of the desired viscosity and homogeneity are cast or coated into green tapes using methods well-known in the art.

The green tapes of the present invention can be formed into multilayer capacitors and similar elec-tronic devices using known technigues. For example, green tapes of the present invention can be coated, e.g., by screen stenciling, with a noble metal elec-trode coating in the desired pattern. The inked tapes can then be stacked to provide alternate dielectric and electrode layers with alternate electrode layers exposed on opposite edges of the stack. The stack can -then be compressed under pressure, as is known in the art, and then fired to provide a monolithic multilayer capacitor.
The edges with exposed electrodes are metaliæed with a conductive metal paint. This can be done before the ; stack is fired, or after such firing, depending upon the firing temperature required and the metal paste utilized. (See U.S. Patent 4,075,681 for an exemplary method of preparing monolithic multilayer capacitors.) Preferred green tapes have a thickness of from 2.5 to 25 microns; more preferably they have a thickness of from 5 to 18 microns; most preferably they have a thickness of from 5 to 10 microns.
.

The following preparations and examples are illustrative of the present invention, and are not to be construed as limiting. All parts and percentages are by weight unless otherwise specified. For ease of conversion, no~e that 1 mil eguals 25.4 microns.

3~,773A-F -13-.. . :

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3~5 Example 1 and Comparative Experiments 1-2 A powder suspension was prepared by dis-persing in toluene a commercial dielectric powder designated Z5UBL702, available from Solid State Dielectrics Company, Sun Valley, California, U.S.
The suspension was stirred constantly.

The following general procedure was followed for Example 1 and comparative Experiments 1-2. An aliguot o~ the suspension described hereinabove was weighed out. The ali~uot was allowed to settle for thirty (30) minutes. Then, the supernatant liguid was siphoned off to enrich the suspension so that it con-tained approximately a 1:1 weight ratio of powder and toluene. The enriched suspension was vigorously mixed with an ethylcellulose solution prepared using a mix-ture of toluene, isopropanol, and plasticizers. Three different types of ethylcellulose were employed, i.e., three slips were prepared. Each slip was cast on a glass plate using a doctor blade. The cast suspensions were dried at room temperature to give green tapes having thicknesses of from 0.3 to 1.2 mils (7.6-30~5 microns). The results are summarized in Table I.

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~7~385 The green tape prepared using ETHOCEL 45 is more suitable for use in preparing dielectric com-ponents than are green tapes prepared using ETHOCEL~ 7 and ETHOCE~ 20.

Example 2 A slip having the following composition (in grams) was prepared:

Dielectric Ceramic powder800.0 (Z5UBL702) ETHOCEL 45 68.0 Surfactant 4.0 Atlas G3300 (I.C.I. America), amine salt of alkylarylsulfonate Plasticizer benzyl butyl phthalate 46.4 butanetriol 3.6 Solvent methyl ethyl ketone 486.0 isopropanol 93.6 ethanol 96.0 Total 1597.6 In the preparation of the slip, the dielec~
tric p~wder was ball-milled in a mixture of mPthyl ethyl ketone and isopropanol for six hours using ~hree-eighths inch (O.95 cm~ zir~onia balls.
ETHOCEL~ 45 was dissolved separately in a mixture of methyl ethyl ketone and isopropanol together with benzyl butyl phthalate and butanetriol. The ETHOCEL~ 45 solution was then poured into the mill jar, and total slip was mill~d for an additional 32,773A-F -16-.
-.. , . . : - . - :

-~ 7 ~ ~5 twen~y hours. The viscosity of the slip was 800cps. It was cast on a glass plate using a doctor blade. The cast slip was dried to give a green tape having a thickness of 0.3 mil (7.6 microns).
The tape easily peeled off the glass plate and was observed to have good mechanical strength and flex-ibility.

When the above procedure was repeated using 800.0 g of Z5U502L (a commercial dielectric powder a~ailable fr~m Tam Ceramics, Niagara Falls, New York) or using 800.0 g of X7P1~2H (a commercial dielectric powder avail~ble from Tam Ceramics, Niagara Falls, New York), the results were comparable to those obtained for Z5UBL702 above.

E~am~e 3 The slip of Example 2 was cast on a poly-propylene tape using a doctor blade. The cast slip was dried to give a dry green tape having a thickn~ss of O.9 mil (~2.9 microns). The dry green tape was stripped continuously from the substrate tape.
Recta~gular-shaped two-inch by four-inch (5 by 10 cm~
sheets were punched out of the green tape and were screen-printed with a palladium-containing electrode ink. About 20 layers of sheets with electrode were stacked and backed up with 10 blank sheets on eithex side to increase the i~tegrity of the xesulting lam-inate. The laminate was hot pressed at 70C and 2,500 psig~ Green chips diced out of the laminates were subjected to polymer burnout and sintering. Good ceramic chips were obtained with no delamination.
Dielectric properties of the chips were within the 32,773A-F ~17-, . ~ : .

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specifications of Z5U as determined by the Electronic Industries Associatioh.

Example 4 A slip having the following composition (in grams) was prepared:

Dielectric ceramic powder800.0 (Z5U502L) ETHOCEL~ 100 63.0 S~rfactant 4.0 Atlas G3300 (I.C.I. America), amine salt of alkylarylsulfonate Plasticizer Benzyl butylphthalate 80.0 Oleic acid 16.0 Mineral oil 16.0 Solvent l,l,1-trichloroethane 1793 0 : In the preparation of the slip, the dielec~
tric powder was ball-milled in a mixture of 1,1,1-trichloroethane, surfactant and mineral oil f~r ~hree hours using three-eights inch (O.95 cm) zirconia balls.
ETHOCEL~ 100 was dissolved separately in a mi~ture of l,l,l-trichloroethane with benæyl butylphthalate and oleic acid. The ET~OCEL~ 100 solution was poured into the mill jar, and the total slip was milled for an additional six hours. The 51ip was cast on a glass plate using a doctor blade. The cast slip was dried at room temperature to give gxaen t~pes having a -thickness o fro~ 0.20 mil (5 micro~s) to 3.0 mils (75 ~lcrons).

32,773A-F -18-.
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i ~74;~5 --lg--The tape easily peeled off the glass plate and was ~ observed to have good mechanical strength and flex-ibility.

Exam~le 5 5A slip was prepared having the same compo-sition and in the same manner as the slip of Example 4, except that ETHOCE ~ 200 was used for the ETHOCEL~ 100.
The slip was cast on a glass plate using a doctor blade and dried at room temperature to give green tapes less than 25 microns in thickness. The tapes were free--standing and flexible.

Surprisingly, it can be seen from the pre-ceding examples and comparative experiments that the use of specific ethylcellulose binders results in very thin, green tapes having outstanding physical proper-ties, whereas the use of ethylcellulose binders not within the specifications described herein does not give green tapes having the desired physical proper-ties .

32,773A-F -19-.. . .
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A green ceramic precursor tape which comprises a free-standing, flexible layer having a thickenss not greater than about 25 microns and prepared from a slip composition having:
(a) a dielectric component in an amount sufficient to provide said tape with desired dielectric properties;
(b) a binder comprising alkylcellulose ether or a hydroxyalkylcellulose ether having a viscosity of 40 to 110 centipoise (measured at 25°C as a 5 weight percent solution in a solvent that is 80 weight percent toluene and 2 weight percent ethanol) in an amount sufficient to bind the dielectric component into said tape upon removal of solvent; and (c) a solvent in an amount sufficient to solubilize components (a) and (b) and to enable said tape to be formed.

2. A tape of claim 1 wherein the dielectric component is barium titanate.

3. A tape of claim 1 wherein the binder is an ethylcellulose.

4. A tape of claim 3 wherein the alkylcellulose ether is ethylcellulose.

5. A tape of Claim 4 wherein the ethylcellulose has an ethoxyl content of from 44 to 53 weight percent and the viscosity is greater than about 40 centipoise.

20a

6. A tape of claim 2 or 5 wherein the ethoxyl content is from 48.0 to 49.5 weight percent and the viscosity is from 40 to 60 centipoise.

7. A tape of claim 2 or 5 wherein the ethoxyl content is from 48.0 to 49.5 weight percent and the viscosity is from 90 to 110 centipoise.

8. A tape of claim 1 having a thickness of from 5 to 18 microns.

9. A tape of claim 1 wherein the slip also contains a surfactant.

10. A tape of claim 1 wherein the slip also contains a plasticizer.

11. A tape of claim 1 wherein the binder is a thermoplastic methylcellulose and the solvent is water.

12. A capacitor prepared using a green tape of claim 1.

13. A process for preparing a green ceramic precursor tape which comprises applying a thin layer of a coating comprising a slip composition as defined in claim 1 to a flexible or nonflexible, nonporous carrier, controlling the thickness of the coating, drying the coating/carrier and removing the coating (green tape) from the carrier.