FROM: James D. Herard ************************************************************** Subject: FAB: Electroless Tin What does this customer want IN the vias (are there any?) you'd need to tent the vias with a resist during both E-less Sn (or SnPb) and during Ni/Au. is SnPb ok instead of Sn? How thick Au? Is Immersion SnPb OK? What is the substrate material (fr4, ptfe, polyimid?) can the vias later be coated with soldermask or the like? Have you thought about wave solder on the one side with a hot air level or won't that be planar enough? (you'd need to plug your vias then from the Au side after Au but before Sn) I'll review with our mfg eng's on this one. we're doing an Immersion SnPb process today on a product, and we have the NiAu ability, but I'm not sure of the compatability of the resist systems needed for each of the processes. (ie can you cover one while you do the other? You can reach me at [log in to unmask] Jim Herard IBM Microelectronics Endicott Pnl Mfg Quality Engineering James Herard x77026 KBLE/014-3 Quality Engineer *************************************************************** ********* Get it While you Can ********************* *************************************************************** *** Forwarding note from SMTP3 --IINUS1 11/05/96 15:40 ***