Hello Paul,
The reason is : Vial holes, plugged by solder that come from the HASL
process.
You have to instruct the PCBs fab to increase the air pressure during the
HASL.
Other reason is, when you have plugging via holes requirement and the HASL
process is done after the plugging process and not before.

Best  Regards

ROKAH Reuven
Chief Engineer
ECI Telecom LTD.
Operations Division
30 Hasivim St. Petah-Tikva 49517
                 ISRAEL
Tel: 972-3-9266734    Mobile:972-55-786734
Fax: 972-3-9266480
e mail: [log in to unmask]



                      "Black, Paul"
                      <[log in to unmask]         To:      [log in to unmask]
                      OM>                      cc:
                      Sent by: TechNet         Subject: [TN] Solder Balls
                      <[log in to unmask]
                      >


                      24/09/2003 14:57
                      Please respond
                      to "TechNet
                      E-Mail Forum.";
                      Please respond
                      to "Black, Paul"





Hi TechNet Gurus,

Has anyone experienced solder balls resulting from the board fabrication
process? We have been getting them from our offshore supplier for a few
months now and have had to add a wash step to our no-clean process. We know
that it's fro the board because we have run bare boards through the reflow
oven using the normal reflow recipe from that board and we are seeing 25-60
random solder balls on our 9" x 7", 8 layer, .062", HASL FR4  board. We
believe the problem is caused by uncured solder mask that erupts when
exposed to reflow temperatures but have been unsuccessful trying to
eliminate the problem. We have tried baking the board @ 320 F for anywhere
from 1.5 - 6 hours. This has reduced the number of solder balls to maybe a
dozen or less. Anyone have a suggestion?


Thank you,
Paul Black
Manufacturing Engineer
Kronos


---------------------------------------------------
Technet Mail List provided as a free 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
-----------------------------------------------------