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January 2010

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Subject:
From:
Dale Ritzen <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Dale Ritzen <[log in to unmask]>
Date:
Wed, 27 Jan 2010 10:25:07 -0600
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Rob,
Without knowing anything more about this problem or looking at pictures on Steve's website, I would say you are moving in the right direction with the reduction. In cases like this we might use a "home-plate" type print with both apertures tapering to a point under the passive component. This removes much of the paste mass from the point where it tends to ball up and flow out from under the component during reflow. I'm sure there are many other potential fixes for this problem, but reducing the actual amount of paste by putting less of it in the area that has a tendency to cause the solder balls is a good start.

Dale Ritzen, CQA
Quality Manager/ISO Management Representative
Austin Manufacturing Services

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rob Strecker
Sent: Wednesday, January 27, 2010 10:13 AM
To: [log in to unmask]
Subject: [TN] Solder Ball Under Chip Cap

We recently received a call from one of our customers that their boards are failing Hi-Pot test.  They sent us a picture of a solder ball under one of the chip caps (package 1825).  Apparently it's present on all 50 boards we built and always in the same place.  We are using leaded paste for this build and the stencil we received was from the previous manufacture who could not fix the problem and went to hand soldering the part (info we got after the fact).  I have inspected the stencil and it looks fine.  The apertures are a 1:1, so the only thing I can think of is getting a reduction of some kind on the stencil.  I will send the picture to Steve to get it posted.

 

Thanks,

 

Rob Strecker 


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