You may want to conduct some mechanical integrity tests
(vibration, shock, etc) before concluding whether it's a
thermal stress, metallurgical, or mechanical issue. We came
across this problem some years ago in those components which
are heavy or mounted flush onto the PCB (single-sided). We
don't see this problem anymore after we minimized the
hole-to-lead clearance and ensured proper mechanical support
of the assembly. Autoinsertion yield may not become worse if
your FR1 board have the holes punched. Punched holes usually
have slightly larger entry diameter.

Good luck.

K.K. Chin
Artesyn Technologies
www.artesyn.com




From: afng <[log in to unmask]> AT NetMail on 08/18/98 03:11
      AM EDT

To:   [log in to unmask] AT NetMail@ccmail2
cc:    (bcc: KK Chin)
Subject:  [TN] Solder crack





Message :  I have a problem on solder joint reliability. It
was detected that some of the solder joint was having minute
solder crack on the DIP IC joints. I believe some might call
it solder creep. The crack is so severe that it cause 'open'
joint. It only happened after many temperature cycle or the
board was on the field for more than 6 months. The board is
a through-hole single sided board,substrate is FR1. Apart
from the IC joints, we also detect similar problems on other
joints. The crack is only visible with close inspection, the
crack seems to separate the fillet away from the pad. The
board goes through wave soldering once, and no touch up on
the joints. Initially we though it could be due to crack in
the thickened intermetallic layer. But, as know we suspect
it could be due to creep on the solder itself. WE are using
eutectic solder composition, and would not likely to change
to other type of solder composition and substrate materials
due to cost impact. I hope someone with similar problem can
enlighten us on any possible solution.

Thank you

############################################################
####
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
############################################################
####