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From:
Brent Stayer <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 20 Jul 2000 16:20:52 -0400
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Ken,
From the limited amount of information given, I can only assume that there was a fabrication process problem.  All the HALT and HASS in the world will not make "bad" product "good".  You MAY learn that the problem is better or worse than expected by performing HALT/HASS, but only if you have a control group of "good" product.  If you have a "bad" fabrication process, HALT/HASS may only weaken the product and not actually precipitate the failure.  If you decide to ship the product, it may fail even earlier in the field than if no HALT/HASS were performed.  

I have been asked to perform the exact type of screen in the past (different company then I work for today).  I was given evidence that the fabrication process was out of control and told to screen out the "bad" product so that the "good" product could be shipped.  I could not do it.....As I stated earlier, HALT/HASS cannot make "bad" product "good".

Brent
Reliability/Quality Engineer

>>> [log in to unmask] 07/20/00 03:29PM >>>
John,
We have seen the PTH via crack (circumferential) which results into open
during ICT. At that moment our boards are gone thr' two reflow cycle (225c
max) and one wave cycle.

How can I select chamber profile so that it will weed out bad one? Is there
any guide lines? My boards are loaded with components and need resolution ASAP.

re,
ken patel

At 12:03 PM 7/20/2000 -0400, you wrote:
>Ken mentions:
>
>> Reliability/Quality Expert,
>> How can I select the thermal stress/shock profile for loaded board if I
>want
>> to precipitate the fab problem. Boards are functionally passed but belongs
>> to suspect date code.
>>
>> I am looking for a profile in the following format.
>
>Hi Ken,
>
>Before you do any testing, a good, root cause failure analysis is
>required before specifying a failure acceleration method.
>
>Once you've conclusively identified the specifc cause of your
>module failure, you can tailor a stress test to weed out that
>specific problem (or fix the root cause failure reason, better yet!)
>
>Without the root cause failure identified, you may end
>up spending a lot of money, and potentially ruining a lot
>of good modules  doing accelerated life/reliability testing,
>with minimal return.
>
>Rgds
>John
>
>
>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>John Brewer
>Supervisor, Component Engineering
>Raleigh, NC
>(919)-266-8870
>[log in to unmask]
>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>
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______________________________________________________
Ken Patel                       Phone:  (408) 490-6804
1708 McCarthy Blvd.             Fax:    (408) 490-6859
Milpitas, CA 95035

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