You might go back a few steps in the process and HASL boards prior to
soldermask and edge plating. If that looks good, apply soldermask and HASL.
If that looks good, edge plate and and HASL. Somewhere in all of this there
should be some remarkable changes in coverage.

Best regards

Lee

J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389


----- Original Message -----
From: "sumxp" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, July 26, 2006 10:38 AM
Subject: [TN] What causing dewetting on HASL pcb


> We have a HASL(Sn/Pb) board(FR4) with gold finger edge that having
> dewetting issue across 30% of the lands.We have done below evaluation to
> find out the root cause;
> 1)use short,medium,long profile,increase and reduce peak temp.
> 2)change to different brand of solder paste.
> 3)clean the board with IPA.
> 4)Apply a layer of flux on pcb and reflow it without paste,clean the board
> & follow by normal smt solder paste reflow process.
> All above countermeasures couldn't solve dewetting issue.We brought in the
> pcb vendor & they couldn't give any answer except coming back to us to say
> that the board is nothing wrong.
> Could anyone explain to me what went wrong with the board.It is a Sn/Pb
> process.We are seeing dewetting even though the baord is not populated.
>
> Thanks in advance..
>
> rgds
> sumxp
>
> ---------------------------------------------------
> 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
> -----------------------------------------------------
>

---------------------------------------------------
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
-----------------------------------------------------