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