Victor,
The TM-650 discribes the bow and twist. You can use them for PCB and PCBA.
In the 7711/21 you can see the procedure how to get them flush again......
If you need some more answers please visit etech.training/forum
Here you can post your questions like on this Forum but you can also see
and read the questions from the past.
2017-03-29 10:17 GMT+02:00 Grossmann, Günter <[log in to unmask]>:
> We sometimes do bow and twist measurements on assembled boards, but only
> on small quantities (<10).
> We place the PCBs on a granite table and measure the distance from the PCB
> to the table by focussing on various points with a lens with a small depth
> of field. Table and focus are motorised with X-Y-Z coordinates.
> Takes quite a while because it's not automated.
>
>
> Best regards
>
> Günter
>
>
>
>
> > -----Ursprüngliche Nachricht-----
> > Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Giamis, Andy
> > Gesendet: Mittwoch, 29. März 2017 06:01
> > An: [log in to unmask]
> > Betreff: Re: [TN] IPC-TM-650, 2.4.22, Bow & Twist
> >
> > I have used precision blocks to create a picture frame and placed it on a
> > precision flat stone.
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Lum Wee Mei
> > Sent: Tuesday, March 28, 2017 10:14 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] IPC-TM-650, 2.4.22, Bow & Twist
> >
> > 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,
> > >
>
--
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