This is true, however I get the feeling from what our mechanical team is
not saying that our assemblies are exceeding the general requirement. 


Jeffrey McGlaughlin, CID 
Engineering Designer EAS 
4-2-50 room 
x-7582 Phone 
(614)458-7582 Fax 


-----Original Message-----
From: Guy Ramsey [mailto:[log in to unmask]] 
Sent: Thursday, March 08, 2007 9:08 AM
To: 'TechNet E-Mail Forum'; McGlaughlin, Jeffrey A
Subject: RE: [TN] Post Assembly Bow and Twist

Kevin gave you the number and the method but it is not a requirement.
The
requirement is form fit function. The standard says something like
mounting
the board in the assembly must not damage the assembly. You have a
special
case that the standard does not address.  


*** We are Moving - March 20, 2007 ***
Guy Ramsey
R&D Assembly
1660 East Race Street
Allentown PA 18109-9580
(610) 264-1887
FAX (610) 264-1877

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of McGlaughlin, Jeffrey
A
Sent: Thursday, March 08, 2007 7:05 AM
To: [log in to unmask]
Subject: [TN] Post Assembly Bow and Twist

Technet and DesignersCouncil Gurus -

I have been asked by our mechanical engineering group to find out if
there
is a standard or specification for post assembly flatness of printed
circuit
cards.  This has never been an issue for functional failure but a new
design
requires that a row of LEDs mate to a display panel mask such that no
light
leaks from one LED cell to the next. Their concern is that post assembly
bow
and twist will over stress solder joints and board copper if they
mechanically stress the cards by pressing/pulling them flat to an
assembly
frame.  Can anyone direct me to a standard or advise me on the maximum
allowable bow and twist for this type of situation?


Jeffrey McGlaughlin, CID
Engineering Designer
Battelle
505 King Avenue
Columbus Ohio 43201-2693
(614)424-7582 Phone
(614)458-7582 Fax 

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