I received some PCBA assembled at one of our contract manufacturer This is double sided / mixed tech assembly. There are some locations where one could either use a BGA or a QFP. Currently we are using the BGA version. The stencil does not have aperture opening to print QFP ( they use different stencil ), however on the QFP pads, I see some purple / brownish pads, almost exhibiting corrosive traits. The PCB are supposed to immersion silver. I see some small solder balls here and there. Test via pads look good. The SMT solder joint has transparent residue typical of No clean paste The contract manufacterer should be using eith AIM NC 253 or 293 or 291 or Indium NC SMQ 92J. I can share some photos. Any ideas as to what could have happened / chemistry guess as to the flux / paste ? I am still in the preliminary data collection mode --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------