Nick:

Good questions and all valid........A new group here in USA is
considering implementing a whisker test and is having good success to
date................can you supply known good and known whisker prone
samples to verify??

Also what committment to this kind of service could you commit to? They
want to work with several consistant supliers and serve as a continuous
process monitoring support lab along with continuous improvements.

We at ON Semi will have data from Japan in 2 days   let's chat next
week.

Are there salts involved in this accelerated testing for whiskers?
What are the leadframes or underlayers?

To the forum, please respond if you have similar interests....

John Lynch
Director Integrated Manufacturing
Program Director, Lead-Free
ON Semiconductor

Nick Vo wrote:
>
> I am an engineer at Motorola working on lead-free plating for
> leadframe packages.  Currently, I am performing a whisker study with a
> Japanese company that has an accelrated whisker test.  They were able
> to grow whiskers in only three days.  We have some initial SEMs from
> them but are doing our own analysis at our Japan facility.  The catch
> using this outside source is that they will not disclose their test
> method.  The only thing that I know about their test is that they do
> not subject the samples to additional external mechanical stresses
> (i.e. bending, compression, etc.).
>
> We are beginning a test in Austin to confirm the results of the
> outside source.  One of our subcontractors informed us that they were
> also successful in growing whiskers in three days using an autoclave
> environment.
>
> I have a few questions for the discussion group.
>
> 1)  From the whisker discussions has autoclave been mentioned as an
> accelerated whisker test?  If yes, was the test successful in forming
> whiskers in a short period.
>
> 2)  What other storage conditions have been tried?  I am aware that
> 50-55C is optimal in terms of temperature, and humidity as well as
> external compressive stress may have an influence.  We performed one
> test in Austin with 55C storage and bending but without humidity.  We
> were unsuccessful in forming and/or detecting whiskers.
>
> 3)  What is the inspection method used to detect whiskers?  We
> originally tried to use optical microscopy but were unable to detect
> whiskers.  The Japanese supplier used SEM and were successful in
> detecting whiskers.
>
> 4)  Have the discussions generated an accelerated whisker test?  If
> yes, has the acceleration factor been defined and verified?
>
> 5)  Have the discussions generated a criteria for what types of
> whiskers are acceptable and the maximum allowable whisker length?  We
> have seen three different types of whiskers, lump, flower, and
> needle.  The lump and flower type are probably not a problem.  The
> needle whiskers observed were as long as 100+ microns.
>
> Any insight on Sn whiskers, testing, and failure criteria is
> appreciated.  Thank you for your time
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