There is a small problem.  Material suppliers do not like to certify the 1/2
mil (12.5 micron) materials to IPC specs.  Thickness tolerance on adhesive
alone is a problem with covers or bond ply.  Dimensional Stability is
another.

My belief is that too much is based on peel strength.  We have even gone so
far as to specify maximum peels on some materials.  This confuses the
material guys like you never saw before.

Chuck Brummer
Acuson

-----Original Message-----
From: Steve Kelly [mailto:[log in to unmask]]
Sent: Thursday, August 08, 2002 1:09 PM
To: [log in to unmask]
Subject: Re: [TN] flex circuit specs


Good flex circuit drawings should follow the same guidelines as rigid
board drawings - i.e. use IPC specs for the material call-outs -
IPC-4202/4203 and 4204. Do a detailed layer stack. Detail the finish -
i.e. HASL , Gold or Immersion Tin with the appropriate specs and do a
very detailed dimensioned drawing with the 0,0 start position from a
hole centre or artwork feature - not off an edge. Specifications for the
material thickness tolerances are in the above mentioned IPC specs but
most of the vendors easily surpass the tolerances. Regards Steve Kelly

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Roseann Strength
Sent: Wednesday, August 07, 2002 5:08 PM
To: [log in to unmask]
Subject: [TN] flex circuit specs

Can anyone refer me to specifications for fabrication drawings for flex
circuits?
I did not find any board thickness tolerancing for thin flexible
circuits IPC-D-300G (using 1/2 mil construction).
Also, is there a 'standard'  guideline for flex fab drawings?
Thanks

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