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March 2008

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Subject:
From:
John Burke <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, John Burke <[log in to unmask]>
Date:
Wed, 5 Mar 2008 10:37:52 -0800
Content-Type:
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text/plain (184 lines)
I actually use X-ray and here are the reasons:

1	The "tab" is a power connection and I need to ensure minimum voiding
in the cross section

2	The "tab" is a thermal connection and the thermal dissipation scales
linearly with cross sectional area connection.

 
 
John Burke
 
(408) 515 4992
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: Wednesday, March 05, 2008 9:57 AM
To: [log in to unmask]
Subject: Re: [TN] QFN Thermal Plane Voiding

Folks,
  Is x-ray inspection part of assembly process?   The thermal header would
not be exposed if it was not to be soldered properly.

Victor,


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey (EHCOE)
Sent: Wednesday, March 05, 2008 10:32 AM
To: [log in to unmask]
Subject: Re: [TN] QFN Thermal Plane Voiding

This will not go un-noticed, young David.
Older than dirt Dewey

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Willis
Sent: Wednesday, March 05, 2008 7:31 AM
To: [log in to unmask]
Subject: Re: [TN] QFN Thermal Plane Voiding

Yes you are right young David the only criteria for LGA/QFN is based on
inspection of the side terminations.

Bob Willis
2 Fourth Ave, Chelmsford, Essex, CM1 4HA England
Tel: (44) 1245 351502
Fax: (44) 1245 496123
Mobile: 07860 775858
 
www.ASKbobwillis.com
 
Book your place on Bob's "Step by Step Failure Analysis Workshop" 14th
May www.ASKbobwillis.com/faworkshops.pdf
 


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: 05 March 2008 14:14
To: [log in to unmask]
Subject: Re: [TN] QFN Thermal Plane Voiding

Hi Vector! Where is the 25% requirement in A610? I did not find a 
requirement listed for the thermal pad coverage. 

Dave Hillman
Rockwell Collins
[log in to unmask]




Victor Hernandez <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
03/05/2008 07:49 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
[log in to unmask]


To
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cc

Subject
[TN] QFN Thermal Plane Voiding






Fellow TechNetters:

The 25% solder voiding has been an accepted rule of thumb for QFN, Quad
Flat w/No Leads, IPC-A-610D sec. 8.2.13.   Is there any other guideline
out there.

Victor,



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