Hi Chris,

1. The solder pads are look like that the solder has not attached to the component. There is solder on the pads and you can clearly see the component has been there correctly but for some reason it is not anymore. The component sometimes is broken off i.e. there sometimes are parts of components left but usually there is only the solder left. Like somebody would have removed the component by using pliers (this naturally is not the case here).
2. Components are SMD components as I said and maybe you could find the reason by checking manufacturing dates. Problem with this route is that this problem has been there many months and the contract manufacturer does not have big stocks. Also PCB solderability does not seem to be problem according to the soldering results.
3. Manufacturing process is very normal: paste printing, SMD assembly, AOI checking, THD assembly (manual), wave soldering, testing and packing. The missing components are SMD components assembled by assembling machine. In AOI phase the components are still there without any defect codes.
4. The components are on the top side of the PCB and glue is not considered needed in our products.
5. I’m not aware about our contract manufacturer’s machine adjustment, servicing or cleaning procedure or policies. Currently our PCB’s have only one fiducial mark even if adding another has started to some of the products. But AOI, as I said, does not find misplacements. What is SMD component reel mishandling, could you be more specific about what you mean?

Thanks and BR,

Ilkka Lehtinen

---

From: Chris Katzko [mailto:[log in to unmask]]
Sent: 11 January 2008 17:27
To: [log in to unmask]
Cc: [log in to unmask]
Subject: 答复: [TGA] SMD components cracking off

Hi Ilkka -

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?  An indication of this would be perfectly solderd pads without components. Missing is 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. Another possiblity is if the tape reels are mishandled before loading or by machine maslfunction.

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

+++  Please note new tel & fax numbers.  +++

Ilkka Lehtinen <[log in to unmask]>
发件人:  TGAsia <[log in to unmask]>

2008-01-11 16:54

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主题	[TGA] SMD components cracking off

Hi,

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?


Thanks in advance,

Ilkka Lehtinen
Quality Manager
Teleste (Suzhou)