Cedric,

How were the "fibers" in the solder joint able to short the SMT pads?

Did the "fiber" grow to be a short or just strung from one joint to the other?

If I saw that on a PCA I would assume that there was insufficient flux on the PCA or the flux was "baked" on the PCA before it hit the wave....

Paul 

Paul Edwards
Process/Quality Engineering
Surface Art Engineering

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Monday, January 17, 2011 12:56 PM
To: [log in to unmask]
Subject: Re: [TN] Board failure due to fibber like fragments of alloy after wave soldering

Hi Cedric,

 

What does your last solder analysis say? You do get your pot analyzed don't
you?

 

Steve

 

 

****

From: TechNet [mailto:[log in to unmask]] On Behalf Of Cedric ORAIN
Sent: Monday, January 17, 2011 2:57 PM
To: [log in to unmask]
Subject: [TN] Board failure due to fibber like fragments of alloy after wave
soldering

 

After wave soldering of boards with both SMD and PTH components, 18% of the

boards failed during ICT.

The failure is due to shorts between SMD pads. 

 

These shorts are caused by "fibber like" fragments entrapped in solder

joints. We are looking for root cause of this level of waste.

 

These fragments are very similar in aspect with dross that we found on the

top of the wave "head" after the pump stop. You can see dross picture in the

pictures posted here:

 

http://ipc-technet.groupsite.com/gallery/17663

 

The alloy is Sn63Pb37 and the flux is an alcohol based no-clean flux.

Soldering under air atmosphere. The design of the board is ok. Dross is

removed daily.

 

Did you ever encountered this kind of issue (I mean with such a rate of

defect)?

I'm wondering if the aspect of the dross shown in the picture is normal or

is it due to a pollution (metallic pollution: high Cu rate?? / organic

pollution : epoxy, fiber glass fragments ...). 

 

Thanks for your in advance for your help and support,

 

Best regards,

 

Cedric ORAIN



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