TECHNET Archives

July 2006

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Brian Ellis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Brian Ellis <[log in to unmask]>
Date:
Thu, 27 Jul 2006 12:07:35 +0300
Content-Type:
text/plain
Parts/Attachments:
text/plain (57 lines)
The most common cause (but not the only one) of dewetting is abrasive
particles embedded in the copper before the HASL. The use of abrasive
cleaning (either pumice slurry, brushing or using Scotchbrite etc.) is
far too frequent and has the merit of being cheap. A good chemical clean
is better, but will not remove particles already embedded, unless you
etch away several micrometres.

Brian

sumxp wrote:
> 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
> -----------------------------------------------------
>

--
http://www.cypenv.org Cyprus environment/energy
http://www.cypenv.org/worldenv World environment/energy
http://www.cypenv.org/weather Cyprus weather
http://www.cypenv.org/smf/index.php Environment/energy forums
http://groups.yahoo.com/group/cypnature/ Cyprus nature forum

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

ATOM RSS1 RSS2