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June 2010

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From:
"Thayer, Wayne - IIW" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Thayer, Wayne - IIW
Date:
Sat, 5 Jun 2010 08:54:13 -0400
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That's exactly what makes these parts so frustrating--MUST be disconnect:  If you do ground this, power draw increases significantly.  So you can't even use the paddle connection as a joint ground node.

Wayne

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Landman
Sent: Saturday, June 05, 2010 8:46 AM
To: [log in to unmask]
Subject: Re: [TN] Relying on soldermask as an insulator

I have used quite a few QFN parts (analog) that use the paddle as an ground connection so check the datasheet very  carefully.  It's not entirely obvious, esp. with Maxim parts.

Bob Landman

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Pete Houwen
Sent: Thursday, June 03, 2010 10:10 AM
To: [log in to unmask]
Subject: Re: [TN] Relying on soldermask as an insulator

routing should NEVER be placed on the top layer under a QFN.  That "big
paddle" is a heatsink, and should be soldered to a pad on the board.   And
even if you choose not to solder it, how can you inspect production quantity boards well enough to be sure the mask is providing adequate insulation?  It's just asking for trouble.

(but I have seen it done)



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