TECHNET Archives

February 2000

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:
Lou Hart <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 25 Feb 2000 08:47:05 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (27 lines)
Hi Technetters,

(1)  Solder balls:  I feel a little sheepish to bring up a subject that has been discussed many times before, I'm sure, but let me get an opinion.  Our production manager thinks solder balls on assemblies come from holes in the boards (always FR4) that got wet during cleaning after surface mount reflow and were not dried before wave solder.  He says the vaporizing water blows solder around the board, leading to balls.  Searching through the TechNet archives, I found a posting from Bob Willis in Jan 96 where he says "(solder balls) are always present in some from.  The mask is the key issue, if they can not stick to the mask the problem is solved".  Can I get your comment(s).  

(2)  Assembly cleanliness:  How do people assess assembly cleanliness after manufacture?  We use several kinds of flux at different stages of operation here.  Surface mount uses water-based, rework and touchup use organic acid, wave solder uses RMA.  Our cleaner has a formulation supposed to get rid of RMA, but everything goes through it.  What cleanliness measures are or should be used after these cleanings?  I'm most concerned about the final assembly, but am curious about the intermediate stages as well.  The IPC test methods manual has some tests for ionic contamination (Omegameter and Ionograph seems most feasable for production) and some for rosin residue (that seem to require some expensive equipment and take a while).  Questions I'm asking myself are:  Should we be checking both ionic contamination and rosin residue?   And, of course, with what frequency(ies)?  

Thanks for any comments.

Lou Hart
Quality Assurance Manager
Compunetix
412-858-6184

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################

ATOM RSS1 RSS2