Hi Again ThomasA,

<--Reference Note
<On Sat, 2 Aug 2003 19:25:03 Thomi <[log in to unmask]> wrote:

>No, as a matter of fact, with lead free alloys we stay more in the elastic
>(i. e. the non damageing part of deformation) regime, if we use the same
>test acceleration as with Sn-Pb-alloys.
>http://www.weichloeten.de/eureka-leadfree/04gg-comp-rel.pdf
<-----------------

Thanks I found this report very informative. Some notes in case
you feel you need to add more information, correct, or clarify.

Comment:1 The long dwell time 30 minutes at the lowest temperature
of -20C shown in Figure 3 is very interesting as compared to the
shorter dwell/soak time at 120C of 10 minutes. This makes sense
since you wish to allow the compressive strain to set (allow creep
to occur) prior to moving in temperature to the opposite extreme
where creep or plastic deformation occurs more quickly due to the
higher temperature.  I like, and think I understand.

Comment:2 It is interesting that of all the presentations I have seen,
read or questioned on LF that none have described creating this kind
of an ATC cycle. I will have to gently make my rounds again and ask
via email.

Comment:3 I am glad to see cracks starting (shown in Fig: 16)
around 300 cycles, and also seeing the stiffer alloys having longer
cracks sooner.

Comment:4 I now understand what you meant by saying that those who
conduct a rapid ATC might be only operating in the elastic range thus
imparting very little accelerated failure.

Comment:5 The top temperature range of 120C seems a bit high for normal
FR4 considering it's glass transition temperature. Did you use a higher
temperature FR4.

Again Thank You, and Awaiting any FeedBack


YiEngr, MA/NY DDave

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