James Pin holes can occur with out a fracture (in the normal sense) in the copper barrel. These pin holes are usually caused by air bubbles at electroless copper. Glass boundless extending into the barrel will also cause this problem as the copper seal around these bundles is usually poor. Best regards Lee -----Original Message----- From: James Hofer [mailto:[log in to unmask]] Sent: Friday, September 10, 2004 3:53 PM To: TechNet E-Mail Forum; Lee Parker Subject: Re: [TN] Blow Holes -- Where the heck does the moisture come from anyway? However, Were this the case you would see fracturing or voiding of the via. James Hofer Director of Operations Accurate Circuit Engineering 3019 S. Kilson Dr. Santa Ana Ca. 92707-4202 714-546-2162 work 714-473-6127 cell [log in to unmask] ----- Original Message ----- From: "Lee Parker" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, September 10, 2004 12:31 PM Subject: Re: [TN] Blow Holes -- Where the heck does the moisture come from anyway? > Carrie > > If you cross section the vias, remove the solder from the hole and look > at the copper barrels at very high magnification (use and SEM if > possible)you may see pin holes in the copper or glass bundles protruding > into the hole. This coupled with moisture in the dielectric which is > normal can create the mechanism. When the board is quickly heated in > assembly (reflow or wave solder) the moisture is pressurized and flows > out through the pin holes into the barrels blowing the molten solder in > the barrels out onto the board. > > Best regards > > Lee > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Morse, Carrie > Sent: Friday, September 10, 2004 2:33 PM > To: [log in to unmask] > Subject: [TN] Blow Holes -- Where the heck does the moisture come from > anyway? > > Just wondering a few things here at 2:30 on Friday Afternoon: > > 1. What else causes Blow Holes at wave on TH comps? Is it primarily > moisture? > 2. Where does the moisture come from? > 3. Are certain board materials more likely to sponge up the moisture in > the air? > 4. Can hole wall quality play a part in contributing to blow holes? > > -Carrie > > --------------------------------------------------- > 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 847-509-9700 > ext.5315 > ----------------------------------------------------- > > --------------------------------------------------- > 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 847-509-9700 ext.5315 > ----------------------------------------------------- > --------------------------------------------------- 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 847-509-9700 ext.5315 -----------------------------------------------------