Karen, I can not say how opaque mold compounds adhere to silver, but most of the optically clear ones that I am familar with advertise better adhesion to silver ... than say to gold plating [somewhat if a 'dah' statement, I realize, since the gold surface SHOULD be non-reactive]. Steve -----Original Message----- From: Karen Walters [mailto:[log in to unmask]] Sent: Friday, August 27, 2004 11:15 AM To: [log in to unmask] Subject: Re: [TN] Corrosion in lead frames Hi David Hillman I have a question for you. Do you see Ag lead finishes as a problem with mold compound adhesion because of the surface finish. I was told that this could impact the adhesion property and cause moisture ingress problems. Please advise. (Embedded image moved to file: pic11942.pcx) "David D. Hillman" <ddhillma@ROCKWELLC To: [log in to unmask] OLLINS.COM> cc: Sent by: TechNet Subject: Re: [TN] Corrosion in lead frames <[log in to unmask]> 08/26/2004 11:59 AM Please respond to TechNet E-Mail Forum; Please respond to ddhillma Hi Jose! The photo shows what appears to be silver sulfide (based on observations we have made on silver issues at Collins). Depending on the severity of the surface species attack you may or may not be able to chemically restore the silver surface. Having the discoloration may not be an indication that you will have problems - at least in terms of soldering, some discoloration does not impede a flux's ability to create a metallurgical joint. The same assumption may not hold true for wirebonding. Good Luck. Dave Hillman Rockwell Collins Jose Antonio Garcia Ontalba To: [log in to unmask] <ja.garcia@nagare cc: s.com> Subject: Re: [TN] Corrosion in lead frames Sent by: TechNet <[log in to unmask]> 08/26/2004 10:06 AM Please respond to ja.garcia Hello together! hier is the link with the image of my problem. Sure is easier to see it than my explanations! http://www.geocities.com/karlsruhero/Silver_corrosion_image.ppt Thank you for your help! Best regards Jose -----Mensaje original----- De: TechNet [mailto:[log in to unmask]]En nombre de David D. Hillman Enviado el: jueves, 26 de agosto de 2004 15:39 Para: [log in to unmask] Asunto: Re: [TN] Corrosion in lead frames Hi Jose! It has been my observation/experience that silver oxides are clear in appearance, silver chlorides are yellowish in appearance and silver sulfides can be black-to-purpleish in appearance. We have used SERA testing to confirm the surface species identification. I have not observed a red color appearance in conjunction with silver. Good luck on solving the problem. Dave Hillman Rockwell Collins [log in to unmask] Jose Antonio Garcia Ontalba To: [log in to unmask] <ja.garcia@nagare cc: s.com> Subject: Re: [TN] Corrosion in lead frames Sent by: TechNet <[log in to unmask]> 08/25/2004 12:21 PM Please respond to ja.garcia Steve, You are right, I am speaking of an alumina substrate with a Ag/Pt metallization, but I have just realized that I was wrong in my first message: the lead frame is really Ag/Pt and the coating is pure Ag. There is not more metalls involved. I think the red spots are oxides of Ag or Pt or maybe both. But the oxides of silver are not red coloured, aren't they? So, the red spots have to be oxides of Pt... Maybe the tempeature helps the reaction of oxidation of Pt. Anyway I am not sure. What do you think? Thank you very much! Regards Jose -----Mensaje original----- De: TechNet [mailto:[log in to unmask]]En nombre de Creswick, Steven Enviado el: miércoles, 25 de agosto de 2004 18:02 Para: [log in to unmask] Asunto: Re: [TN] Corrosion in lead frames Jose, Could the red-orange color be from exposed, oxidized copper? You did not say whether the lead frame was copper, phosphor bronze, or maybe a Kovar (Fe, Ni, Co) composition. .... although, I am confused by a lead frame having Ag/Pt plating. Hmmm. Possibly, are you speaking of an alumina substrate having Ag/Pt metallization (traces) on it? Steve Creswick - Gentex -----Original Message----- From: Jose Antonio Garcia Ontalba [mailto:[log in to unmask]] Sent: Wednesday, August 25, 2004 10:59 AM To: [log in to unmask] Subject: [TN] Corrosion in lead frames Hello together! I have an hybrid circuit with lead frames for bonding encapsulated with gel. These lead frames are used for bonding the wires of aluminium only with heat (without using solders, flux, etc.). We have made some durations test, after them appears some red-orange spots on the lead frames preferably in the borders, and, in some cases, comes into view blue parts too. We have seen with Infra-Red photographs that this part (wire+lead frame) is by far the warmest of the PCB when it is working, because through it comes high electric flow. The lead frames have a coating of Ag/Pt and the gel's major components are: silicone, Pt (polymerization's activator) and alumina (for the thermal conductivity). The lead frames have not solder nor flux residues. So, anybody could tell me what is happening in the lead frame? I suppose that a chemical reaction involves the Ag and/or the Pt but I have no idea which could be! Thank you all for your help! Best regards -- José Antonio García Ontalba Quality department NAGARES, S.A. Ctra. 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