With Lead Free coming, I imagine warpage will loom large as there is
evidence of joint fracturing due to stress from flexing assembled boards,
especially noted at box build. Proper handling after assembly will be as
important as processing.
Dave C.
-----Original Message-----
From: Guy Ramsey [mailto:[log in to unmask]]
Sent: Tuesday, April 20, 2004 4:16 PM
To: [log in to unmask]
Subject: Re: [TN] PCB Raw card Bow & Twist Tolerance
For bow it is the length of the board. For twist it is the diagonal. But
these are not "requirements" they are "should" best manufacturing practices.
Bow and Twist shall not be sufficient to damage the components or solder
connections in subsequent assembly operations.
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor G.
> Hernandez
> Sent: Tuesday, April 20, 2004 5:00 PM
> To: [log in to unmask]
> Subject: Re: [TN] PCB Raw card Boe & Twist Tolerance
>
> Ramon,
>
> I have seen the 1.5% and 0.75% criteria before. What I
> am not sure
> is % of what base number.
>
> Victor,
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
> Sent: Tuesday, April 20, 2004 1:07 PM
> To: [log in to unmask]
> Subject: Re: [TN] PCB Raw card Boe & Twist Tolerance
>
>
> Hi Victor:
> It should definitely be less than 1.5% for
> THT and less than 0.75% for SMT, which that is what it is for
> a board after it has been soldered.
> JStd.001B 9.2.3
> Regards,
> Ramon
>
> > -----Original Message-----
> > From: Victor G. Hernandez [SMTP:[log in to unmask]]
> > Sent: Tuesday, April 20, 2004 1:02 PM
> > To: [log in to unmask]
> > Subject: [TN] PCB Raw card Boe & Twist Tolerance
> >
> > Steve,
> >
> > What has been your experience with measuring Bow &
> Twist on a raw
> > card. Is there a RULE Of Thumb that can apply generically.
> >
> > Victor,
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