yap.  assembly stress might causes problem if your sensitive parts  
are close to the mounting holes - plus PWA  warpage... the  
combination might spell doom... Design is the key (including PWB  
board balance, especially for large size).
best of luck.
jk
On Aug 25, 2021, at 5:04 PM, Torsten Hagge wrote:

> Hello Raye,
>
> automotive standard is maximum 1000µm/m, VW recommends 500µm/m max  
> stress on PCBA line, depanelization is the worst, but some (AOI)  
> PCB fixing systems are critical, too.
>
> take care,
> Torsten
>
> -----Ursprüngliche Nachricht-----
> Von: TechNet <[log in to unmask]> Im Auftrag von Rivera, Raye
> Gesendet: Mittwoch, 25. August 2021 21:22
> An: [log in to unmask]
> Betreff: [TN] Strain or strain rate spec for PCBAs
>
> Hello Technetizens,
>
> Does anyone know of a spec or criteria for acceptable strain or  
> strain rate for a PCBA?
>
> We are using strain gauges to understand how much strain is placed  
> on a PCBA inside one of our products during typical shipping  
> processes.
>
> I know that IPC-TM-650, 2.4.41.2A tells how to measure coefficient  
> of thermal expansion by this method, but I can't find anything  
> about mechanical force, or how much is too much.
>
> Best regards,
> Raye Rivera
> Quality Manager