Hello, "any idea?",

Some molding compounds are just not adequate for some packages, and vice 
versa. The PQFP will warp as it cures. To my knowledge, environmental 
factors are not as important as the molding compound itself and the package 
design. And it's worse with a thinner package or if you have a heat sink 
integrated into your package. You definitely need to check with this 
specific supplier. The problem probably originates from their backyard.

If you can scrap one, measure its profile once you made sure it sits on the 
body and not on the leads. You should be able to see that warpage or bowing.

Richard Blanchet

 ----------
From: TechNet-request
To: Olly.Kierse
Cc: Technet
Subject: Re: Assy: Lifted lead (QFP)
Date: 25 March, 1997 20:05

Hello Olly and Technetters,

Could you tell me what is LQFP ?. And I am not too sure the meaning of
"thicker version" of the std QFP....

The interesting part is that it only happened on only one part number,
and the board contains other  QFPs of other vendors, but no problem.

Any idea ???

 ----------------------------------------------------------------------------
 ----------------------



At 09:25 AM 3/25/97 GMT, you wrote:
>Hi Poh,
>
>I've heard of this where a 14x20 LQFP was used. Basically
>a combination of internal TCE mismatch and absorbed
>moisture caused the bowing through reflow.
>       The 'fix' was to move to a thicker version of the
>same part (std QFP).
>
>regards
>
>Olly
>

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