Thanks Mike, All good advice. I'll get with IMAPS..If they're as helpful as Technet, I'll be sure to get an answer. Ron Vandendolder Telaxis Communications -----Original Message----- From: Mike Fenner [mailto:[log in to unmask]] Sent: Wednesday, February 14, 2001 5:12 PM To: TechNet E-Mail Forum.; Vandendolder, Ron Subject: Re: [TN] Potential of galvanic couple of dissimilar metals Well I waited and waited for someone to answer this as I don't have a definitive answer, but no one has so here is a definite 1/2 cents worth.. The idea of using bonding tabs to ensure compatibility of bond wire to surface is not novel. The semiconductor and to a lesser extent the chip and wire hybrid people have been doing it for years. It may be that you might be better off looking in those directions than this forum. I believe that IMAPS has a similar forum to this, I don't know if the semi conductor people do, but you could try SEMI. Another idea you might be able to steal from them is a getter. These mop up moisture in package cavities. It might also be worth looking at the mono molecular or at least very thin coatings like Alpha's Paralene, might not upset your values. Mike ----- Original Message ----- From: "Vandendolder, Ron" <[log in to unmask]> To: <[log in to unmask]> Sent: Monday, February 12, 2001 10:23 PM Subject: [TN] Potential of galvanic couple of dissimilar metals > I've got a conundrum wrapped in riddle inside an enigma. > > We are planning to make an bondwire interconnection from a microwave RF > board that is copper/nickel gold plated to an epoxy PCB > that is copper/ immersion silver plated using 1 mil aluminum wire. Our > plan is to silver epoxy a bimetallic copper/aluminum tab onto the microwave > RF board so that the aluminum faces up. Then we plan to solder another > bimetallic copper/aluminum tab onto the > epoxy PCB by reflowing with solder paste, again, leaving the aluminum side > up. Now we have aluminum pads on both boards that we can aluminum wire > bond. > > My concern is whether the all the dissimilar metals are a galvanic cell > waiting to happen! I should mention that the end assembly is mounted in a > cast housing, which although leak tested, does not have either a hermetic > seal or an inert atmosphere. > The product will be located outdoors and must last 10 years. > > Has anyone had past successes using a similar technique that they'd care to > share? > > Thanks in advance. > > Ron VandenDolder > [log in to unmask] > > -------------------------------------------------------------------- ------------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional > information, or 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 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------