LOL - if we were following the old rules then there would not be a
component called a BGA.............. :-)

Dave

On Thu, Sep 20, 2018 at 9:07 AM, 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
> On Sep 20, 2018, at 9:54 AM, Stadem, Richard D wrote:
>
> Adding to what Dave said; you don't get something for nothing! Different
>> alloys have different physical characteristics and are used for
>> correspondingly different purposes and applications. Don't attempt to use
>> something not AABUS and fully documented on the applicable BOM.
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
>> Sent: Thursday, September 20, 2018 6:57 AM
>> To: [log in to unmask]
>> Subject: Re: [TN] High Temp SnPb solder
>>
>> Hi Ben - yes, there are differences in the mechanical properties and the
>> solder joint microstructures for the "high temp" alloys. Most of those
>> alloys have applications in component construction, specifically in
>> component die attachment. One very common alloy used frequently in a
>> number
>> of applications is the 10Sn88Pb2Ag alloy.
>>
>> Dave Hillman
>> Rockwell Collins
>> [log in to unmask]
>>
>> On Thu, Sep 20, 2018 at 6:40 AM, Gumpert, Ben <[log in to unmask]>
>> wrote:
>>
>> TechNetters,
>>>
>>> J-STD-006 has a series of 'high temp' SnPb alloys (some with Ag) that are
>>> close in SOL/LIQ temps. I'm familiar with Sn10Pb90 as a common high-temp
>>> ball on ceramic BGAs, but I haven't seen the others used. Are there any
>>> differences (e.g. mechanical properties) among these that would drive
>>> selection, other than the SOL/LIQ?
>>> Are some alloys more readily available than others?
>>>
>>> Ben
>>>
>>>