Purple discoloration on gold plated boards is due to the formation of 'purple of Cassius', which yu should be able to find out about in your chemistry books. I believe that it is due to some contamination absorbed into the resin of the laminate. I remember this problem 15 years ago, and a change of laminate supplier had the problem go away. Dougal Dougal Stewart Product Development Manager Viasystems Selkirk Ltd Selkirk, Scotland, TD7 5EJ Tel: +44 1750 21601 Fax:+44 1750 22513 email [log in to unmask] > -----Original Message----- > From: [log in to unmask] [SMTP:[log in to unmask]] > Sent: Tuesday, May 19, 1998 7:00 AM > To: [log in to unmask] > Subject: [TN] DISCOLORATION > > HI ! EVERYBODY > I HAVE A PROBLEM. > AFTER I/R REFLOW PROCESS, PCB WAS DISCOLORED AROUND > GOLD PLATING, ESPECIALLY EXPOSED EPOXY AREA CHANGED > LIGHT VIOLET. > THE PCB WAS APPLIED A HASL PROCESS AND EDGE CONNECTOR > GOLD PLATING. WE TESTED MANY TIMES AND ONLY PCB WHICH > WAS APPLIED THE HASL PROCESS AND GOLD PLATING PROCESS. > > THERE IS LOW PEAK OF Sn BY SEM ANALYSIS ON THE DISCOLORED > SPECIMEN ONLY. > > THE GOLD PLATING CHEMICAL MAKER SAID : > IF AMINO-COMPOUNDS WHICH IS USED HARDNER OF EPOXY > MATERIAL JOIN WITH A CYANIDE, PCB CAN DISCOLORATION AFTER > THERMAL SHOCK. > > PLEASE HELP ME WHY THE PCB WAS DISCOLORED AS SOON AS > POSSIBLE. > > ################################################################ > TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for > additional information. > For technical support contact Hugo Scaramuzza at [log in to unmask] or > 847-509-9700 ext.312 > ################################################################ ################################################################ TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################