On Tue, 23 Apr 2002 16:34:48 -0400, Guy Ramsey <[log in to unmask]> wrote:

>I have seen this condition caused by over active chipwave and excessive
>setting on an omega wave. The omega wave is a vibrating plate in the
>solderwave that produces turbulence in the lambda wave (main wave) that is
>perpendicular to the normal wave dynamics. The action forces solder up
>through the board, bridges form at the heels of the springs that form the
>socket contacts.
>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]]On Behalf Of Andre Leclair
>> Sent: Tuesday, April 23, 2002 2:27 PM
>> To: [log in to unmask]
>> Subject: Re: [TN] Shorts in PLCC Sockets
>>
>>
>> base on your description, the following questions come to mind:
>> 1. Could the part have come with the condition?
>> We are investigating with the part manufacture with no results as of yet.
>> They are
>>
>>  2. Is there an open area in the PCB, near the socket in question,
through
>> wich solder can over flow and get underneath the socket?
>>
>> There are no holes in the PCB near the socket where solder extra solder
>> could have migrated under the socket and then under the pin
>> retainer.  When
>> the socket was removed there was now evidance that extra solder had been
>> between the board and the socket base.  For the amount of solder that was
>> between the base and the main body of the socket there should have been
>> evidance of solder ( the plastic body marks very easily at 500'F).
>>
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The wave setup used is an Electrovert Ultrapak 445
Flux Lonco 3355-11
Conveyer speed 5.6FPM Airknife on
Lamda 6-9rpm
chip wave 6-9rpm
Omega wave 70%

Could this be the cause?  I checked another 12 units and found the exact
same short in the same general area inside the socket but no solder between
the PCB and the base of the socket(44 pin).  The other 3 PLCC sockets(32
pin) on the board that are only 2-3 inches away are perfectly fine.
The 2 previous 1000pcs runs had no problems using the above settings.

Any SMT parts near the sockets are at least .150" from the pins and are all
603 or 402 parts.

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