We once had the same problem. 

The production of a cca worked out right.

After the transfer to an EMS problems occured. Solderbeading. while he was 

using the same layer, same solderpaste, same components. The EMS changed 

stencil design from homeplate to negative homeplate to standard 1:1, 

reduced the aperturesize, used our stencil. Varied the viscosity of the 

solderpaste, placement pressure for the components, solderingprofile. 

Nothing worked out right, until he renewed his airconditioningsystem.



Kind regard



Frank 







Von:

Rob Strecker <[log in to unmask]>

An:

[log in to unmask]

Datum:

27.01.2010 17:14

Betreff:

[TN] Solder Ball Under Chip Cap

Gesendet von:

TechNet <[log in to unmask]>







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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