Subject: | |
From: | |
Reply To: | TechNet E-Mail Forum. |
Date: | Thu, 5 Nov 1998 10:45:01 -0500 |
Content-Type: | text/plain |
Parts/Attachments: |
|
|
We have recently seen a failure of an assembly in a humidity chamber. There
were two things observed. First, on an external layer, power traces (+25V) were
very close to ground traces (~20 mils), and an apparent electrical bridge caused
a short and a burned the area. Secondly, other areas of the board appeared to
have white residue and broken down soldermask bridging between connector pins.
Some of these areas took up a number of pins (thumb print size).
I vaguely remember and issue where assemblies that were not thoroughly cleaned
could leave residuals (chlorides?) and that when subjected to a humid
environment could break down soldermask. I also believe that humid chlorides
can crystallize and can be influenced by electrical potentials between pins -
causing shorts. However, that's where my memory breaks down.
Can anybody provide some clarity on potential reasons for soldermask to
breakdown in a humidity chamber?
Thank you,
Anders P. Pedersen * 407-729-2143 (ph)
Harris Aerospace * 407-729-2097 (fax)
P.O. Box 94000, MS22-4842 * [log in to unmask]
Melbourne, FL 32902 http://www.harris.com/
################################################################
TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################
|
|
|