Hey Jim,
Susan's got it right - if you need flat panels measure panels and if you
need flat boards you measure boards. IPC-TM-650 2.4.22 works for either.
Somewhere in your procurement documentation you must have specified delivery
in panel form. Did you happen to reference IPC-A-610 anywhere?
IPC-A-610 Rev. C Section 10.6
Acceptable - Class 1,2,3
* Bow and twist does not cause damage during post solder
assembly operations or end use. Consider ''Form, Fit and
Function'' and product reliability.
Defect - Class - 1,2,3
* Bow and twist causes damage during post solder assembly
operations or end use.
Note: Bow and twist after soldering should not exceed 1.5%
for through-hole and 0.75% for surface mount printed board
applications
I've seen this before - panels fail but the final boards will pass. Our
Quality Engineers would request a waiver prior to shipping or we'd scrap
them.
Hans
AC-130 Gunship Motto: "You can run but you'll only die tired."
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hans M. Hinners
Electronics Engineer
Warner Robins - Air Logistics Center (WR-ALC/LUGE)
226 Cochran Street
Robins AFB GA 31098-1622
mailto:[log in to unmask]
Com: (478) 926 - 5224
Fax: (478) 926 - 4911
DSN Prefix: 468
-----Original Message-----
From: Marsico, James [mailto:[log in to unmask]]
Sent: Thursday, March 14, 2002 8:12 AM
To: [log in to unmask]
Subject: Re: [TN] Board Bow and Twist
Well, I got two responses with two different interpretations...
Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879
-----Original Message-----
From: Franklin D Asbell [SMTP:[log in to unmask]]
Sent: Thursday, March 14, 2002 8:17 AM
To: TechNet E-Mail Forum.; Marsico, James
Subject: Re: [TN] Board Bow and Twist
Regarding bow/twist for arrays, prior to separation, the array is
considered
a board and subject to the bow/twist requirements of 6012.
At least this is how I interpret it, and apply it in my shop.
Regards,
Franklin D Asbell
Network Circuits, Inc.
Irving, Texas 75061
----- Original Message -----
From: "Marsico, James" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, March 14, 2002 6:48 AM
Subject: [TN] Board Bow and Twist
> I think this is a no-brainer, but here goes... We were delivered
boards
in
> panel form from one of our suppliers. At Incoming Inspection, the
panel
was
> rejected for excessive bow (>75% for SMT) and returned the
supplier. The
> supplier called me and said that even though the panel exceeded
the bow
> requirement, the individual boards were acceptable. When I quoted
the bow
> and twist requirement from IPC-6012, "Panels which contain
multiple
printed
> boards which are assembled on the panel and later separated shall
be
> assessed in panel form." , he said yes, you measure the individual
boards
in
> the panel. I need clarification.
> Thanks,
> Jim Marsico
> Senior Engineer
> Production Engineering
> EDO Electronics Systems Group
> [log in to unmask] <mailto:[log in to unmask]>
> 631-595-5879
>
>
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