TECHNET Archives

September 1997

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:
Reply To:
TechNet Mail Forum.
Date:
Wed, 17 Sep 1997 11:14:55 MDT
Content-Type:
text/plain
Parts/Attachments:
text/plain (43 lines)
     Hello,

     Currently we are finding electromigration problem on SOIC16 resistor
     networks of a particular datecode (9551, pretty old) assembled on a
     particular card early July. We found from the component supplier that
     this lot (9551) was produced in a site in China (closed now due to
     business reasons as claimed by the supplier). Mystically this lot
     (produced on 9551) ended up in our assembly contractor several months
     ago.

     The analysis found Bromide inside the components. The component
     supplier claimed that there was no way that Bromide could be generated
     by their process and the problem was caused by the PCB assembly
     process. However, they were not aware of moisture sensitivity levels
     when asked (which is surprising I think). Checked with the assembly
     and found all processes, i.e. reflow, wave and clean, were not
     abnormal. The assembly uses water soluble paste. The resistor networks
     in question experiences 4 thermal excursions (top and bottom reflow,
     selective wave and fountain wave). These components are near a TH
     connector which is fountain soldered using mini-wave.

     From the above history, could anyone tell what might be the possible
     causes? The analyses we are doing are C-SAM  looking for cracks and
     delaminations and moisture content.

     Appreciate any comments.

     Thanks,

     Yuan

##############################################################
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.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
##############################################################


ATOM RSS1 RSS2