ASTM_D_1825_-_03.pdf

Designation:D 1825 03An American National StandardStandard Practice forEtching and Cleaning Copper-Clad Electrical InsulatingMaterials and Thermosetting Laminates for ElectricalTesting1This standard is issued under the fixed designation D 1825;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice describes a procedure for etching andcleaning copper-clad electrical insulating materials and ther-mosetting laminates for electrical testing.1.2 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.For specificwarning statements see 6.3 and 6.4.2.Referenced Documents2.1 ASTM Standards:2D 1867 Specification for Copper-Clad Thermosetting Lami-nates for Printed Wiring3.Significance and Use3.1 The procedure used for etching the copper foil from thebase insulating materials may significantly affect the results ofelectrical tests.This is true primarily for two reasons.First,thegeometry of the copper which remains and forms the electrodesis in part determined by the etching procedure;this is particu-larly true of closely spaced electrodes on the same surfacewhen the property to be measured depends on the electrodegeometry.Second,electrical conductance in the material,particularly surface conductance,may be affected by thechemicals used to etch the copper,the length of time ofetching,and the manner in which the specimen is cleaned afteretching.3.2 This practice standardizes the etching procedure in orderto provide a basis for comparison of electrical properties ofcopper-clad electrical insulating materials and thermosettinglaminates.Experience has shown that the test circuit can beaccurately prepared using this procedure,and that the specimenwill be substantially free of etching-induced,electrically-conductive contaminants.3.3 It is recognized that commercial processes utilized tomanufacture printed circuits may differ appreciably from thispractice.Therefore,the results of tests on specimens etched inaccordance with this practice may differ from results obtainedon specimens etched in a commercial process.Specimensshould be etched in accordance with a procedure different fromthis practice,if it is desired to determine the influence of thedifferent procedure on electrical properties.4.Reagents and Materials4.1 Ferric Chloride Etching Solution(554 g/L)Dissolve554 g of ferric chloride(FeCl3)or 925 g of the hydrate(FeCl36H2O)in water and dilute to 1 L.4.2 Oxalic Acid Solution(10%)Dissolve 103.5 g ofoxalic acid in water and dilute to 1 L.4.3 Pumice,Grade FFF.5.Test Specimen5.1 Prepare the test specimen to consist of an area ofsuitable size of any copper-clad electrical insulating sheetmaterial or a thermosetting laminate such as described inSpecification D 1867,or an actual finished printed circuitelement.6.Procedure6.1 Etch the test specimen with vigorous aeration for aminimum time(Note 1)in FeCl3solution maintained at 24 to45C.Renew the etching solution when the etching timeexceeds 15 min for 1-oz copper or 30 min for 2-oz copper.NOTE1The time to produce a clean pattern with a minimum ofundercutting is approximately 7 min for 1-oz copper and 15 min for 2-ozcopper,using fresh FeCl3solution.1This practice is under the jurisdiction of ASTM Committee D09 on Electricaland Electronic Insulating Materials and is the direct responsibility of SubcommitteeD09.07 on Flexible and Rigid Insulating Materials.Current edition approved Oct 1,2003.Published November 2003.Originallyapproved in 1961.Last previous edition approved in 2002 as D 1825 92(2002).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.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.6.2 After removal of the copper,immediately wash thespecimen with running tap water at 16 to 32C for 2 to 5 min.Thereafter,keep the specimen from drying and proceed with-out delay until reaching the step described in 6.7.6.3 Immerse the specimen in a 10%solution of oxalic acidin water at 16 to 32C for 15 to 20 min.Provide gentlecirculation of the oxalic acid solution during this period.(WarningOxalic acid is toxic,handle with precautionsapplicable for using toxic materials in the laboratory.Flush thespecimen with running tap water at 16 to 32C.)6.4 Scrub the specimen with Grade FFF pumice to removethe resist,or wipe off the resist with a lint-free cloth moistenedwith a suitab