Since the root cause is still unclear, can
you provide some information about the failure mode?
For example:
1. What is the appearance of the solder pads
in the missing component locations? Is there evidence the component
was broken off (ie, a solder joint was formed and then fractured) or any
indication of solderability issues (ie, the pads show de-wetting/non-wetting)?
Keep in mind solderability problems could be due to component issues
as well as PCB, but we examine the evidence we have.
2. If a component solderability issue is
suspected, you might try tracing the failures to date codes, but with passives
used in bulk that might be difficult.
3. What type and sequence of soldering processes
are used? At what step are the missing components soldered?
4. Are the components normally glued when
placed? Any evidence of problems?
5. Is missed placement a possibility? In
other words, does the assembly equipment or downstream AOI (if used) detect
a missed placement? Anindicationofthiswouldbeperfectlysolderdpadswithoutcomponents.Missingis
possible if the placement mechanisms are not properly adjusted, dirty or
worn. I'm assuming they are placed with a high-speed chip shooter, vacuum
suction force and timing may be an issue.Anotherpossiblityisifthetapereelsaremishandledbeforeloadingorbymachinemaslfunction.
TGAsia has many experienced assembly engineers,
if you provide more information, perhaps they can help.
Regards,
C.B. Katzko, CTO
Meadville Group
e-mail [log in to unmask]
tel +86 21 3774 7528
fax +86 21 3774 7590
mobile +86 13817362590
I'm Mr. Ilkka Lehtinen, a Quality Manager in Teleste Corporation's (a
Finnish company) manufacturing company in Suzhou, China. It's honor for
me
also to join this discussion forum.
Our contract manufacturer has a problem they cannot solve themselves with
SMD components: every now and then we find boards that have one or two
SMD
capacitors, resistors or inductors fallen off the board somewhere during
the
manufacturing process. The resistors and capacitors are 5-sided termination
components and inductors are bottom only termination components. Normal
stuff. The size is 0603.
The problem is not location specific so it's not caused by some mishandling
or that some areas are somehow prone to this kind of behavior.
I'm out of glues. Has anybody faced this kind of problem or have any idea?