Thank you all for your information. Now, next: Opens in BGA on Immersion silver. MICROvoids detected by X-ray on : free pads, ordinary smt joints, BGA solder joints (ball to circuit pad location). BGA rework? BGA replacement? SCRAP?????? I fear that the story begins to be similar to the black pad nightmare with immersion gold..... Gaby ----- Original Message ----- From: "Dennis Fritz" <[log in to unmask]> To: <[log in to unmask]> Sent: Monday, January 28, 2008 8:17 PM Subject: Re: [TN] Microvoids immersion silver >I will try to answer each question as you ask them. > > In a message dated 1/28/2008 12:32:15 P.M. Eastern Standard Time, > [log in to unmask] writes: > > Dear Netters, > Is there a preferred process for immersion silver finish in order to > minimize microvoids? > Immersion silver vendors have a preferred way for fabricators to operate > the > immersion silver line to minimize/prevent microvoids. Please understand > there are more effects than just the immersion silver bath itself. > > > How do you choose the preferred immersion silver PCB supplier? > Your board supplier is very interactive in the performance of immersion > silver boards. The best plating solution, run poorly by a fabricator can > give > problems and vice versa. Obtain boards from more than one fabricator and > from > various bath suppliers. Probably, the bath vendor has an opinion, from > process audits, how each fabricator is obeying the process information in > the data > sheets. See what works best with your solder paste and wave solder. > Wetting balance, dip-and-look, solder spread are all tests that indicate > good > performance. > > > Which test for bare boards could give the best information? > IPC J-standard 003 for board solderability should be a guide for your > operation. Do you use international IEC standards? > > > Should I perform a print and reflow test for each batch, followed by > x-ray? > The print/reflow test is a good idea, with controlled conditions. However, > I > don't think you will see microvoids with X-ray. You probably need cross > sectioning to see microvoids. > > > Which tests are the suppliers performing? > By suppliers, do you mean board fabricators or plating chemistry > suppliers? > This is not a one stop shop. The board shop should be running process > controls on their microetch for roughness and silver immersion plating > bath. The > plating rate and final thickness are recommended by the bath supplier, > and > should be obeyed in fabrication. Both shop and supplier may be running > assembly > simulation and then cross sectioning to see if there are any microvoids. > > > Thanks, > Gaby > > Dennis Fritz > MacDermid, Inc. > > > > **************Start the year off right. Easy ways to stay in shape. > http://body.aol.com/fitness/winter-exercise?NCID=aolcmp00300000002489 > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > 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 > ----------------------------------------------------- > --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 -----------------------------------------------------