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Subject:	Re: Mounting Hardware to QFP Component Lead
From:	"Whittaker, Dewey (EHCOE)" <[log in to unmask]>
Reply To:	TechNet E-Mail Forum <[log in to unmask]>, Whittaker, Dewey (EHCOE)
Date:	Tue, 15 Jan 2013 16:25:12 +0000
Content-Type:	text/plain
Parts/Attachments:	text/plain (1 lines)

There are many divine principles, disciplines, mandates and theoretical dogmas that have not made their way into IPC-2221, why would you expect  this question, with all the good previously alluded to variables and potential mitigating scenarios, to be covered with a standard keep-out area?

Since you asked again I'll accept your naiveté on this subject matter and state; 0.025 " keep-out clearance from edge of hole to nearest pad geometry.

Dewey

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Tuesday, January 15, 2013 8:37 AM
To: [log in to unmask]
Subject: Re: [TN] Mounting Hardware to QFP Component Lead

True, but I can't help but wonder if I'm missing something...

Of all the issues that the IPC committees have discussed over the last few DECADES, why can't I find anything about mounting structures to component clearance?

hmmm...  dar's gotta be sumpn 'bout dat!

thanks anyway,

Jack

.

On Mon, 14 Jan 2013 19:16:27 +0000, Wayne Thayer <[log in to unmask]<mailto:[log in to unmask]>> wrote:

>If it is a new QFP with the pure copper/very high copper leads then I wouldn't worry about it.  Those leads are so compliant they can absorb amazing amounts of stress.

>

>Wayne Thayer

>

>-----Original Message-----

>From: TechNet [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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