regular shipping should be covered in random vib test (provide your  
assembly passed test in integrated package... not stand alone PWA).   
Unless there are other unique event (like one of them  I dealt with  
in the past - customer officer stick hands in fiber optical module  
that properly packaged for shipping... damaged module... I was told  
it look like pipe bomb in X-ray... 5 digit value module... crying).
best of luck to find the fault party ;-).
jk
On Aug 26, 2021, at 3:13 PM, Rivera, Raye wrote:

> Thank you Richard, Torsten, and Joyce. TechNet comes through again!
>
> Joyce, we have seen damage from PCB flexing during the  
> manufacturing process in the past. In one case it happened at heat  
> sink installation and we fixed it by using a fixture instead of a  
> manual process.
>
> In this case, I know that a device was working before shipment but  
> arrived not working and with lifted pads under a BGA in a pattern  
> that looked like board flex. Also this board is used in several  
> products but only gets these lifted pads in one of them. So I'm  
> fairly certain the damage is happening in shipping. So the  
> acceleration recorders that Richard describes would be a good idea.
>
> Torsten, I've asked for strain gauge testing during drop and  
> vibration testing. So your automotive guideline is very helpful.
>
> Thank you all for sharing your knowledge.
>
> Best regards,
> RAYE RIVERA
> Quality Manager
>
> -----Original Message-----
> From: TechNet <[log in to unmask]> On Behalf Of Yuan-chia Joyce Koo
> Sent: Wednesday, August 25, 2021 5:15 PM
> To: [log in to unmask]
> Subject: Re: [TN] AW: Strain or strain rate spec for PCBAs
>
> [Warning] This email comes from an external source. Be careful of  
> any embedded links and attachments.
>
> 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