look like i just "solder" dated myself. By the way, high temp
assembly usually is LTCC (multi-layer if electrical), glass (if
optical) with solder that gold based... those actually relatively
mechanical strong. Even that, I wouldn't use it for mechanical
support at full strength value - 50% at end of life using actual
high temp strength calculation will let me sleep well at night
without worry any midnight calls. I have to admit, I do not like
living on the edge, margin or redundancy are key on my book (although
many times working on something called "bleeding edge"... brave need
to be smart... I admit I am very much on the stupid side). IMHO.
jk
On Sep 27, 2018, at 10:47 AM, Jack Olson wrote:
> Joyce,
>
> Most of the SMTs in modern electronics have solder as their ONLY
> means of mechanical support.
> (but I have also been in the industry since the 1980's, so I
> remember books like that!)
>
> I always enjoy reading about your experience,
> Jack
>
> On Thu, 20 Sep 2018 10:07:18 -0400, Yuan-chia Joyce Koo
> <[log in to unmask]> wrote:
>
>> according to my book (old), you should NOT count on solder as
>> mechanical support of ANY kind. solder is intended to provide
>> electrical connect, use solder, especially high temp solder (assume
>> you are going to use it at elevated temp for service, or assembly
>> sequence - such as multiple reflows... it is difficult to count on
>> microstructure to be the same as you initially put down).
>> as for FEM purpose, I would use 50% book value that tell you - if
>> i were you...
>> my 1.5 cents.
>> jk
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