It is this Bow & Twist season again.
I often wonder whether someone really measured Bow & Twist on assembled boards. If yes, wonder how it was done as both sides are already populated with components. 

~wee mei~
________________________________________
From: TechNet [[log in to unmask]] on behalf of Joyce Koo [[log in to unmask]]
Sent: Wednesday, March 29, 2017 3:59 AM
To: [log in to unmask]
Subject: Re: [TN] IPC-TM-650, 2.4.22, Bow & Twist

it depends your design. if you have some small parts in the max bow area,
it may flight out upon installation... (1) your PCB should compliant with
bow and twist with simulated reflow - how many time you reflow, including
rework if it required (2) your PCA depend upon what you how you want to
install or support points and what is density and type of parts... better
not be Gyro... those need really flat ;-).
> Fellow TechNetters:
>
>    Does the above stated TM applies to raw cards ONLY?   Is there a
> standard for PCBA?
>
> Victor,
>