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Wed, 30 Sep 2009 17:44:45 -0700 |
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This is the only spec I remember from in the past...
AIR FORCE NAVY AERONAUTICAL DESIGN STANDARD spec... 'AND10387'
Now I have an in house tolerance spec that is general for all board drill holes... (unless otherwise specified...) that way I don't have any holes that are without a declared tolerance.
.014 to .185 = +.003/-.002
.188 to .246 = +.004/-.002
.250 to .750 = +.005/-.002
.765 to 1.00 = +.007/-.003
1.015 to 2.00 = +.010/-.004
2.031 to 3.50 = +.015/-.005
I'm not aware of a "standard" for PCB's for drill hole tolerances per se...
Holes, plated and unplated should be tolerances to make sure that they perform their intended function... which frankly takes some design effort on the part of the designer. Tooling requires different tolerances than through hole parts, or even hardware... vias of course are all together a different matter. You really must use your design judgment when applying tolerances to holes in a board... Worst case analysis of the fit and function should be used to determine how 'loose' you can allow the tolerance to be to still have the design be successful. Tight tolerances usually mean more expense and scrap. Choose wisely... :)
Best regards,
Bill
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of James Mahoney
Sent: Wednesday, September 30, 2009 10:19 AM
To: [log in to unmask]
Subject: Re: [DC] drill tolerance
Typical tolerances
NPTH +/-.004 unless used for alignment which can be +/-.001 or greater
PTH +/-.003
Vias +.000/- Hole size
www.quickturnflex.com
Thank you,
Jim Mahoney
Quick Turn Flex Circuits, LLC
Applications Project Manager
P# 603-821-7071
M# 603-305-6250
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-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Tracy Norton
Sent: Wednesday, September 30, 2009 12:36 PM
To: [log in to unmask]
Subject: [DC] drill tolerance
I just got caught in an embarrassing situation. A client pointed out
that I don't have drill tolerance specified on my fab notes, and wants
it added AND referred to the specific IPC standard
I looked back at all my work as far back as to '98...and there's no
drill dia tolerance callout!
All I need is pointed to specific standard so I can research it and add
to notes
Thanks!
Tracy Norton
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