Following from the EMPF HelpLine in Indianapolis, prepared by John Greaves: We like to use an etch of hydrogen peroxide, water, and ammonium hydroxide Usally as follows: 50% NH OH 3 50% Water and Peroxide (H O ) 2 2 (note: text formating will probably not Email well) We use 20 mL Ammonium Hydroxide 19 mL Water 1 mL 30% Hydrogen Peroxide Also, acetic acid can be used to attack anything with lead in it. It also darkens the surface which probably won't hurt if you are looking at intermetallics. Jim Nelson at Buehler is considered at expert at electronic microsection preparation (probably etching as well) (unfortunately, I believe he retired, or will be soon) John Greaves can be contacted through the EMPF HelpLine at [log in to unmask] or 317.226.5616 ---------- From: TechNet-request To: TechNet Subject: Sn-Pb etch Date: 24 Jan 96 12:13PM Return-Path: <[log in to unmask]> Resent-Date: Wed, 24 Jan 1996 10:34:36 -0800 Old-Return-Path: <[log in to unmask]> From: [log in to unmask] Date: 24 Jan 96 12:13:24 -0600 To: [log in to unmask] (Receipt Notification Requested) Subject: Sn-Pb etch Message-Id: <"Macintosh */PRMD=MOT/ADMD=MOT/C=US/"@MHS> Resent-Message-ID: <"bQaCE.0.Op8.6Od1n"@ipc> Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/2343 X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask] ---------------------------------------------------------------------------- -- Can anyone recommend a method to completely remove the 63-37 solder from a surface, leaving the underlying intermetallics untouched? I have tried hydrochloric acid; it works for solder reflowed on Cu, but in joints with gold it apparently re-precipitates gold artifacts. Any help would be greatly appreciated. Edwin Bradley Motorola