Pull few PWB out of aircraft. You got your design rule spell out for you ;-). Be careful, some of them got heavy metal ground plane built in (edge mount is also ground with screw holes). they are more tolerant to assembly stress. Make sure you are not compare apple to oranges.
Good luck.
Joyce Koo
Materials Researcher - Materials Interconnect Lab
Research In Motion Limited
Office:
(519) 888-7465 x79945
Mobile:
(226) 220-4760
[cid:[log in to unmask]]
________________________________
From: Jack Olson [mailto:[log in to unmask]]
Sent: Monday, January 14, 2013 11:55 AM
To: Joyce Koo
Cc: TechNet E-Mail Forum
Subject: Re: [TN] Mounting Hardware to QFP Component Lead
I understand what you are saying, but in this situation people are recommending moving the QFP144 farther AWAY from the mounting structure.
I can't find any guidance in my IPC documents that would suggest an appropriate clearance from QFP leads to mounting hardware
Jack
On Mon, Jan 14, 2013 at 10:42 AM, Joyce Koo <[log in to unmask]<mailto:[log in to unmask]>> wrote:
It depends. If your board is flexible somewhat and you do require drop test or random vib, and your support points (screw position) is far and in between... you might need to worry, not just assembly (flatness is not a issue as you say), but reliability.
Joyce Koo
Materials Researcher - Materials Interconnect Lab
Research In Motion Limited
Office: (519) 888-7465<tel:%28519%29%20888-7465> 79945
Mobile: (226) 220-4760<tel:%28226%29%20220-4760>
-----Original Message-----
From: TechNet [mailto:[log in to unmask]<mailto:[log in to unmask]>] On Behalf Of Jack Olson
Sent: Monday, January 14, 2013 11:36 AM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: [TN] Mounting Hardware to QFP Component Lead
To the assembly professionals out there:
Have you ever had reliability issues with mounting screws if they are near
a Quad Flat-Pack? My 144 pin land pattern is pretty close (100mils) but we
are mounting the board into a very flat structure (no bowing)
I can't imagine the compression of the board material could affect
gull-wing style lead connections (maybe BGA?) but I don't know...
thanks,
Jack
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