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Publication numberUS3652351 A
Publication typeGrant
Publication dateMar 28, 1972
Filing dateMay 13, 1970
Priority dateMay 13, 1970
Publication numberUS 3652351 A, US 3652351A, US-A-3652351, US3652351 A, US3652351A
InventorsGuisti Medie B
Original AssigneeCarus Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Processes for etching synthetic polymer resins with alkaline alkali metal manganate solutions
US 3652351 A
Abstract
Processes for etching synthetic polymer resins, particularly ABS resins, with aqueous, alkaline solutions of alkali metal manganate (VI) at low temperatures.
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Description  (OCR text may contain errors)

United States Patent Guisti [54] PROCESSES FOR ETCHING SYNTHETIC POLYMER RESINS WITH ALKALINE ALKALI METAL MANGANATE SOLUTIONS Medie B. Gulsti, Spring Valley, Ill.

Cal-us Corporation, La Salle, 11].

May 13, 1970 [72] Inventor:

Assignee:

Filed:

Appl. No.:

[56] References Cited UNITED STATES PATENTS 2,939,772 6/1960 Newman et al ..2 52/79.5

[451 Mar. 28, 1972 3,425,947 2/1969 Rausch et al. ..252/79.5 3,489,625 l/l970 Dell et a1. .,252/79.5

OTHER PUBLICATIONS Zahn et al., Electroplating ABS Graft Polymers," 56(11) 773- 779 1966) of Kunstoffe.

Primary Examiner-Robert F. Burnett Assistant Examiner-R. J. Roche Attorney-Johnston, Root, O'Keeffe, Keil, Thompson & Shurtleff ABSTRACT Processes for etching synthetic polymer resins, particularly ABS resins, with aqueous, alkaline solutions of alkali metal manganate (VI) at low temperatures.

3 Claims, No Drawings INTRODUCTION Synthetic polymer resins, such as acrylonitrile-butadienestyrene interpolymers (ABS plastics), can be prepared for electroless plating with acidic oxidizing systems. These systems have usually consisted of an oxidizing agent, such as chromic acid and a strong acid, such as sulfuric acid. The toxicity of the chromium compounds, their potential hazards as water pollutants, and the fairly high temperatures (55-70 C.) at which these systems are operated have been some of the disadvantages associated with these systems. A system which would produce similar etching of plastic articles made from the synthetic polymer resins but which has fewer of these disadvantages has long been sought.

THE INVENTION It is a principal object of this invention to provide a unique kind of etching pretreatment of plastic objects, particularly those made of electroplatable grades of ABS resins, which are to be first electrolessly and then electrolytically plated.

It is another object of this invention to provide an etching process with a chromium-free, manganate (VI) etching bath at temperatures between 25 and 550 C.

This invention concerns chromium-free etching of synthetic polymer resins, particularly acrylonitrile-butadiene-styrene interpolymers (ABS plastics), at temperatures between about 25 and 555 C. The etching compositions consist essentially of 2.5 to 8.5 percent potassium and/or sodium manganate (Vl), 30 to 70 percent sodium and/or potassium hydroxide, and 2l.567.5 percent water.

The most favorable concentration ranges for these compositions are 40-70 g./l. (4-7%) of the alkali metalmanganate (Vl), 400-600 g./l. (40-60%) of the alkali metal hydroxide, and 230-560 g./l. (23-56%) water, although compositions with concentrations as low as 30 g./l. alkali metal manganate, 300 g./l. alkali metal hydroxide, and 670 g./l. water may demonstrate some etching ability. Temperature ranges for the use of these etching baths are from 25 to 55 C. in general, as the manganate ion concentration increases, the temperature required for etching is lower, and that as both temperature and manganate concentration are increased, the time required for sufficient etching decreases. A five to thirty minute etching period generally is used.

The object of electrolessly depositing a layer of adherent metal on the plastic surface is to provide a base for electrolytic metal plating. Once the electroless deposit is laid, then plating can proceed in much the same way as if a metal were being electroplated.

The usual four steps in electroless plating are conditioning,

sensitizing, activating and chemical plating.

Conditioning prepares the surface to accept and hold a metal deposit. It is sometimes called roughening, and may be accomplished physically (abrasion) or chemically (etching). Usually etching is achieved by soaking in an acidic-oxidizing solution, such as the H SO -CrO etch.

Sensitizing and activating are two steps which accomplish the following: deposit of a thin layer of a tin (II) salt, usually stannous chloride, followed by a dip into a solution containing a noble metal (platinum or palladium salt). The tin is oxidized, and the platinum or palladium is reduced to the metal. The concentration of stannous chloride in the sensitizer is usually about g./l., and the concentration of palladium chloride in the activator is usually between 0.25 and 0.5 g./l. There are various ways to accomplish this end, and different methods and names are used for these two steps, and sometimes they are combined in one step. However, the end result is a fine film of a noble metal which serves as a catalyst for the electroless metal deposition in the final step.

Plating is the final step of the electroless plating procedure. Both copper and nickel have been used. Sometimes a layer of copper is first deposited, followed by a layer of nickel. Copper systems usually consist of copper salts, caustic, other salts, and formaldehyde. Nickel systems usually contain nickel salts and strong reducing agents, such as boranes or hypophosphites.

Water rinses are used between each step to avoid contamination of the baths.

The invention will be further appreciated from the following examples.

EXAMPLE 1 Potassium manganate (V1) is produced in situ by the reaction of potassium permanganate and an alkali metal hydroxide at a temperature of -90 C. Fifty grams of KOH, 5 g. of KMnO and 20 g. of water are mixed and heated to 80-90 C with stirring. The mixture is held at this temperature with stirring until deoxidation reaction is complete, and the solution is bright green. Twenty grams of water are added and the solution is allowed to cool to working temperature. At 40 C., a piece of ABS plastic is etched in this solution for 10 minutes. Satisfactory adhesion of the electroless nickel deposit is achieved.

Adhesion characteristics are judged by several criteria. First a piece of scotch tape was pressed on the freshly electrolessplated plastic and thereafter removed. The tape was then checked to see if any of the metal deposit was pulled off by the pressure sensitive adhesive 'Second, the appearance of the plating is observed to ascertain whether it had a smooth, evenly distributed, glossy finish. Third, the plated plastic was observed under a microscope to check for a fine, smooth grain, even texture and good coverage of the plastic surface by the electroless-plated metal. Fourth, a piece of freshly electroless-plated plastic is scratched in such a way that the plastic substrate formed a curl. The adhesion on the metal deposition to this curl is inspected under the microscope. Finally, by a simple scratch test involving scratching of the electrolessplated metal with a fingernail, adhesion is evaluated as being good if the surface is difiicult or impossible to scratch.

EXAMPLE 2 Forty-five grams of NaOH, 6 gm. of NaMnO and 20 gms. of water are mixed and heated to 8090 C., with stirring, to produce sodium manganate (VI). Twenty-nine grams of water are added, and the solution used as an etchant for ABS plastic at a temperature of 30 C. for 20 minutes. Satisfactory etching is achieved EXAMPLE 3 Twenty-five grams NaOl-l 25 g. of KOH, 2.5 g. of KMnO,, 2.5 g. of NaMnO,, and 20 g. of water are stirred and heated to 8090 C., to produce a mixed manganate (VI) solution. Twenty grams of water are added, and the solution used as an etchant for ABS plastic at a temperature of 30 C. for 20 minutes. Satisfactory etching is achieved.

The aforesaid ABS plastics may be reinforced with fiberglass. Preferably, they are graft polymers or polymer blends of the type described in Us. Pat. No. 3,445,350. The blends contain at least 20 percent by weight of ABS graft polymer, the remainder being polyvinyl chloride, polyurethane, polycarbonates, etc.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the forms herein disclosed being preferred embodiments for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. A process for pretreatment of an electroplatable synthetic polymer article containing at least 20 percent of an acrylonitrile-butadiene-styrene interpolymer to be electrolessly plated which comprises etching a synthetic polymer surface 3. A process'as claimed in claim 1 wherein said polymer article is made of an electroplatable acrylonitrile-butadienestyrene graft polymer, and wherein said etching solution consists essentially of 4-7 percent potassium manganate (Vl), sodium manganate (Vl), or mixtures thereof, 40-60 percent potassium hydroxide, sodium hydroxide, or mixtures thereof, and 23-56 percent water, said percentages being by weight.

t 3 i i k

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2939772 *Jul 18, 1955Jun 7, 1960Turco Products IncProcess for etching aluminum and aluminum alloy surfaces
US3425947 *May 2, 1966Feb 4, 1969Hooker Chemical CorpMethod of treating metal surfaces
US3489625 *Jun 14, 1968Jan 13, 1970Hooker Chemical CorpProcess for metal surface conditioning
Non-Patent Citations
Reference
1 *Zahn et al., Electroplating ABS Graft Polymers, 56(11) 773 779 (1966) of Kunstoffe.
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4042729 *Jun 18, 1975Aug 16, 1977Kollmorgen Technologies CorporationProcess for the activation of resinous bodies for adherent metallization
US4054693 *Jul 9, 1975Oct 18, 1977Kollmorgen Technologies CorporationPermanganate composition
US4073740 *Feb 28, 1977Feb 14, 1978Kollmorgen Technologies CorporationComposition for the activation of resinous bodies for adherent metallization
US4592852 *Jun 7, 1984Jun 3, 1986Enthone, IncorporatedImprove adhesion
US4601783 *May 31, 1985Jul 22, 1986Morton Thiokol, Inc.High concentration sodium permanganate etch batch and its use in desmearing and/or etching printed circuit boards
US4601784 *May 31, 1985Jul 22, 1986Morton Thiokol, Inc.Sodium permanganate etch baths containing a co-ion for permanganate and their use in desmearing and/or etching printed circuit boards
US4629636 *Oct 28, 1985Dec 16, 1986Enthone, IncorporatedAdding secondary oxidant capable of oxidizing manganate ion to permanganate ion
US4820548 *Mar 25, 1988Apr 11, 1989Enthone, IncorporatedThree step process for treating plastics with alkaline permanganate solutions
US4820553 *Mar 9, 1984Apr 11, 1989Allied-Signal Inc.Method for pretreatment of polyesters for metal plating
US4940510 *Jun 1, 1987Jul 10, 1990Digital Equipment CorporationMethod of etching in the presence of positive photoresist
US4948630 *Mar 14, 1989Aug 14, 1990Enthone, Inc.Three step process for treating plastics with alkaline permanganate solutions
US4997724 *May 25, 1988Mar 5, 1991Polyplastics Co., Ltd.With inorganic filler
US5062930 *Jul 24, 1990Nov 5, 1991Shipley Company Inc.Electrolytic permanganate generation
US5229169 *Jan 21, 1992Jul 20, 1993General Electric CompanyMetallization of plastic
US7666471 *Mar 22, 2006Feb 23, 2010Mark WojtaszekPolyimide substrate and method of manufacturing printed wiring board using the same
US8247050Jun 2, 2009Aug 21, 2012Integran Technologies, Inc.Metal-coated polymer article of high durability and vacuum and/or pressure integrity
US8394473Jun 21, 2012Mar 12, 2013Integran Technologies, Inc.Metal-coated polymer article of high durability and vacuum and/or pressure integrity
US8394507Jun 2, 2009Mar 12, 2013Integran Technologies, Inc.Metal-clad polymer article
US8741392Jun 2, 2009Jun 3, 2014Integran Technologies, Inc.Anodically assisted chemical etching of conductive polymers and polymer composites
US8906515May 24, 2010Dec 9, 2014Integran Technologies, Inc.Metal-clad polymer article
US8911878Jan 31, 2013Dec 16, 2014Integran Technologies Inc.Structural metal-clad polymer article
US8916248Feb 1, 2013Dec 23, 2014Integran Technologies, Inc.Metal-coated polymer article
EP0139090A1 *Jun 30, 1984May 2, 1985Schering AktiengesellschaftProcess for the pre-treatment of polyimides
EP0207586A1 *Mar 27, 1986Jan 7, 1987Macdermid IncorporatedSodium permanganate etch baths and their use in cleaning, desmearing and/or etching resinous substrates
EP0207587A1 *Mar 27, 1986Jan 7, 1987Morton Thiokol, Inc.High concentration sodium permanganate etch bath and its use in desmearing and/or etching printed circuit boards
WO1986000085A1 *May 8, 1985Jan 3, 1986EnthoneComposition and process for treating plastics with alkaline permanganate solutions
Classifications
U.S. Classification216/83, 205/210, 252/79.5, 252/79.1
International ClassificationC23C18/20, C23C18/22
Cooperative ClassificationC23C18/22
European ClassificationC23C18/22
Legal Events
DateCodeEventDescription
Apr 23, 1990ASAssignment
Owner name: GLENFED CAPITAL CORP., ILLINOIS
Free format text: MORTGAGE;ASSIGNOR:CARUS CORPORATION;REEL/FRAME:005293/0081
Effective date: 19891103
Jan 16, 1990ASAssignment
Owner name: CARUS CORPORATION, A DE CORP., ILLINOIS
Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:GLENFED FINANCIAL CORPORATION;REEL/FRAME:005237/0900
Effective date: 19891212
Jan 16, 1990AS17Release by secured party
Owner name: CARUS CORPORATION, 315 FIFTH STREET, PERU, IL A DE
Owner name: GLENFED FINANCIAL CORPORATION
Effective date: 19891212
Nov 2, 1989AS17Release by secured party
Owner name: CARUS CORPORATION, A DE CORP.
Owner name: FIDELCOR BUSINESS CREDIT CORPORATION, FORMERLY TRE
Effective date: 19891023
Nov 2, 1989ASAssignment
Owner name: CARUS CORPORATION, A DE CORP.
Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:FIDELCOR BUSINESS CREDIT CORPORATION, FORMERLY TREFOIL CAPITAL CORPORATION;REEL/FRAME:005255/0001
Effective date: 19891023
Jul 8, 1988AS06Security interest
Owner name: CARUS CORPORATION
Effective date: 19880629
Owner name: GLENFED FINANCIAL CORPORATION, 104 CARNEGIE CENTER
Jul 8, 1988ASAssignment
Owner name: GLENFED FINANCIAL CORPORATION, 104 CARNEGIE CENTER
Free format text: SECURITY INTEREST;ASSIGNOR:CARUS CORPORATION;REEL/FRAME:004910/0193
Effective date: 19880629
Owner name: GLENFED FINANCIAL CORPORATION,NEW JERSEY
Jan 18, 1984ASAssignment
Owner name: TREFOIL CAPITAL CORPORATION 332 SOUTH MICHIGAN AVE
Free format text: SECURITY INTEREST;ASSIGNOR:CARUS CORPORATION A DE CORP;REEL/FRAME:004214/0261
Effective date: 19840113
Jan 18, 1984AS06Security interest
Owner name: CARUS CORPORATION A DE CORP
Owner name: TREFOIL CAPITAL CORPORATION 332 SOUTH MICHIGAN AVE
Effective date: 19840113