Bruce, DBC stands for Direct Bonded Copper. It's a process where you plate Cu on substrates and often used in for example hightemp amp applications. Stellar Industries is one of many who make this.. http://www.stellarind.com/5metllz.html Yes I know, the FET needs a very good thermal path and wire bond. To solder the FET with Au/Sn requires high temperature, but if a substrate has combined ThickFilm (to which you mount components with Ag-epoxy) with DBC (to which you solder the FET) and want to replace the FET. That's a problem. Our Ag-epoxy don't appreciate high temperatures and you can't avoid heating up the surrounding components, when trying to remove the FET, because of the the concept (TF & DBC). From there, I see two ways. Either replace the epoxy or replace the solder to one kind where the surrounding temperature, when removing FET, won't harm the Ag-epoxy. So, a low(-er) temperature solder around 160-200degC would be nice. Any ideas? Anyone? __________________________________________________ Jan Merstrand Microwave MCM, Design/Production Support Ericsson Microwave Systems AB. Defence Manufacturing Office address: Bergfotsgatan 2, SE-431 84 Mölndal Phone: +46 31 747 0725, Fax: +46 31 747 3515 > -----Original Message----- > From: Misner, Bruce [mailto:[log in to unmask]] > Sent: den 30 mars 2000 16:11 > To: [log in to unmask] > Subject: Re: [TN] Solder at lower temperature > > > Jan, > > The FET requires 2 things: excellent thermal path and wire bonds. AuSn > provides a thin interface with minimal voiding without flux > (although N2 > enviornment or blanket is required). This is good for both > requirements and > hence has always been the material of choice in this > situation, especially > for high rel applications (I see you are a Defense > contractor). It also has > the added benefit of not leaching Au (because it already is > 80% Au) and > allows additional processing of other areas of the assembly > at solder temps > without reflowing the original interface. Unfortunately, I'm > not familar > with acronim "DBC" for substrate (European vs American?). If > you can better > define this material I might be able to make other suggestions for FET > attach. > > One last note is that FETs can reach high delta T junction temp. This > combined with the operating temp can bring the interface > dangerously in the > range of typical solder (SN63) reflow temps. Hope this helps. > > Bruce Misner > > > ---------- > > From: Jan Merstrand > (EMW)[SMTP:[log in to unmask]] > > Reply To: TechNet E-Mail Forum.;Jan Merstrand (EMW) > > Sent: Thursday, March 30, 2000 4:11 AM > > To: [log in to unmask] > > Subject: [TN] Solder at lower temperature > > > > Hi guys and girls!! > > > > I have a question that I think many of you can answer. > > Today we solder FET chips with Au/Sn solder onto a DBC > substrate with Au > > surface. > > The soldering area of the FET is Chromium/Nickel/Silver. > > > > I want to replace the Au/Sn solder with "something else".. > I don't want to > > glue the chip to place, only solder. > > The FET working temperature reaches up to 120degC. > > > > Any ideas on what kind of solder to use? > > __________________________________________________ > > Jan Merstrand > > Microwave MCM, Design/Production Support > > Ericsson Microwave Systems AB. Defence Manufacturing > > Office address: Bergfotsgatan 2, SE-431 84 Mölndal > > Phone: +46 31 747 0725, Fax: +46 31 747 3515 > > > > ############################################################## > > TechNet Mail List provided as a free service by IPC using > LISTSERV 1.8c > > ############################################################## > > To subscribe/unsubscribe, send a message to [log in to unmask] with > > following text in > > the body: > > To subscribe: SUBSCRIBE TECHNET <your full name> > > To unsubscribe: SIGNOFF TECHNET > > ############################################################## > > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > > additional > > information. > > If you need assistance - contact Keach Sasamori at [log in to unmask] or > > 847-509-9700 ext.5315 > > ############################################################## > > > > ############################################################## > TechNet Mail List provided as a free service by IPC using > LISTSERV 1.8c > ############################################################## > To subscribe/unsubscribe, send a message to [log in to unmask] > with following text in > the body: > To subscribe: SUBSCRIBE TECHNET <your full name> > To unsubscribe: SIGNOFF TECHNET > ############################################################## > Please visit IPC web site (http://www.ipc.org/html/forum.htm) > for additional > information. > If you need assistance - contact Keach Sasamori at [log in to unmask] or > 847-509-9700 ext.5315 > ############################################################## > ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. 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