What is the header/lead base material.   What is the P/N?   Do you have any cross sections of the solder joint you can share.  Perhaps I missed this answer.

Victor,

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of jonathan noquil
Sent: Monday, April 02, 2012 4:16 PM
To: [log in to unmask]
Subject: Re: [TN] how to pass solder joint reliability of a 3.2 mm board (16 layers) for QFN packae

Thanks Dennis:

I will check your report. Yes we have been passing with other components
with no issue on Cycling but not this QFN (8 leads), QFN seems easy to
crack on its joint when mounting on a thick PC board.

Iwill check and learn from the report
thanks

On Mon, Apr 2, 2012 at 2:13 PM, Dennis Fritz <[log in to unmask]> wrote:

> Johnathan,
>
> There is a great body of knowledge about solder joint reliability at both
> mild thermal cycle and harsh thermal cycle at the JCAA-JGPP report location
> under NASA TEERM:
> http://teerm.nasa.gov/LeadFreeSolderTestingForHighReliability_Proj1.htm
>
> The project 2 results report is at
> http://teerm.nasa.gov/nasa_dodleadfreeelectronics_proj2.htm
>
> I am puzzled why you think you cannot pass 1000 cycles at a delta of 100
> degrees C.  In both studies, but lead based and Pb-free solders passed far
> more cycles than that.   In fact, the Pb-free boards from test 2 are
> probably still being cycled at Boeing in Seattle.  In harsh cycle,
> lead-based solders perform best, in mild (100C) cycles, Pb-free solders
> perform best.
>
> Denny Fritz
>
>
>
>
>  -----Original Message-----
> From: jonathan noquil <[log in to unmask]>
> To: TechNet <[log in to unmask]>
> Sent: Mon, Apr 2, 2012 12:55 pm
> Subject: [TN] how to pass solder joint reliability of a 3.2 mm board (16
> layers) for QFN packae
>
> Hi All
>
> Need some suggestions on how to handle solderjoint issue (How to tweak to
> pass TMCL1000 cycles- 0 to 100C) on QFN packages ( 5 x 6 x 1.0 mm with 8
> pins).
> Finish is Pure Sn
> Board is 16 layers 3.2 mm, HASL finish.
>
> Does someone had an experience to share?
>
> thanks
>
>
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