ASTM_B_727_-_04_2014.pdf

Designation:B72704(Reapproved 2014)Standard Practice forPreparation of Plastics Materials for Electroplating1This standard is issued under the fixed designation B727;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice is a guide to the surface preparation ofplastic materials for decorative and functional electroplating,where the sequence of chemical treatments may include:cleaning,conditioning,etching,neutralizing,catalyzing,accelerating,and autocatalytic metal deposition.Surface prepa-ration also includes electrodeposition of metallic strike coat-ings immediately after autocatalytic metal deposition.Thesetreatments result in the deposition of thin conductive metalfilms on the surface of molded-plastic materials,and aredescribed in this practice.1.2 Once molded-plastics materials have been madeconductive,they may be electroplated with a metal or combi-nation of metals in conventional electroplating solutions.Theelectroplating solutions and their use are beyond the scope ofthis practice.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.(See Section 4.)2.Referenced Documents2.1 ASTM Standards:2B532 Specification for Appearance of Electroplated PlasticSurfacesB533 Test Method for Peel Strength of Metal ElectroplatedPlasticsB553 Test Method for Thermal Cycling of ElectroplatedPlastics(Withdrawn 1991)3B604 Specification for Decorative Electroplated Coatings ofCopper Plus Nickel Plus Chromium on Plastics3.Significance and Use3.1 A variety of metals can be electrodeposited on plasticsfor decorative or engineering purposes.The most widely usedcoating consists of three layerscopper plus nickel pluschromiumfor decorative applications.However,brass,silver,tin,lead,cadmium,zinc,gold,other metals,andcombinations of these are used for special purposes.The key toproducing electroplated plastics of high quality lies in the caretaken in preparing plastics for electroplating.The informationcontained in this practice is useful in controlling processes forthe preparation of plastics for electroplating.4.Hazards4.1 Some chemical solutions are exothermic upon mixing orin use,thereby requiring cooling and proper containment toprevent injury to personnel.4.2 For details on the proper operation and safety precau-tions to be followed by vapor degreasing,seeASTM STP310.45.General Considerations5.1 Nature of Plastics Suitable for Electroplating:5.1.1 Plastics suitable for electroplating may be a combina-tion of one or more polymers so formulated as to allowselective etching of one or more constituents.The mostcommonly electroplated material,acrylonitrile-butadiene-styrene(ABS),is a terpolymer.During etching,soft butadienerubber particles dispersed in the acrylonitrile-styrene matrixare selectively attacked.The microscopic pockets formed bythe etching process provide sites for the physical interlockingof the plastic substrate and subsequently applied metalliccoatings.The resultant mechanical bonding is instrumental inachieving metal to plastic adhesion.5.2 Plastics Suitable for Electroplating:5.2.1 The plastics materials commonly used for injectionmolded articles to be electroplated are:1This practice is under the jurisdiction of ASTM Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 onPre Treatment.Current edition approved Nov.1,2014.Published November 2014.Originallyapproved in 1983.Discontinued January 2004 and reinstated in 2004 as B72704.Last previous edition approved in 2009 as B72709.DOI:10.1520/B0727-04R14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Handbook of Vapor Degreasing,ASTM STP 310A,ASTM,1976.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.2.1.1 Acrylonitrile-butadiene-styrene(ABS),5.2.1.2 Polypropylene,5.2.1.3 Polysulfone,5.2.1.4 Modified Polyphenylene Oxide,5.2.1.5 Polycarbonate,5.2.1.6 Polyester,and5.2.1.7 Nylon.5.2.2 The preparation of these materials for electroplatinggenerally involves the basic steps described in this practice,butsubstantial variations may be necessary to achieve optimumresults with plastics other th