Dave,

I always suggest reading the manufacturer's information. Philips should know how to use their own parts.

Please visit ............
http://www.semiconductors.philips.com/acrobat_download/various/Surface_mount_reflow_soldering.pdf

On page 16 they discuss the recommendations for large pads and thermal attachment.

The numbers are 20-35%, not 70%. remember, this may change by component manufacturer, so the other guys may be right about 70%, but for the components they are using.

Good Luck

Steve Mikell
[log in to unmask]

> ----- Original Message -----
> From: "Dave Seymour" <[log in to unmask]>
> To: [log in to unmask]
> Subject: [TN] SO8 with Heatslug
> Date:         Tue, 28 Mar 2006 10:30:33 -0500
> 
> 
> Currently using a Phillips part,
> 
> http://www.semiconductors.philips.com/pip/NE57814DD.html
> 
> This is a  standard SO8 package with a large "heat slug pad" under the part.
> 
> During reflow the part is floating off center and causing shorts to the
> lead pads.
> I believe this because of the the volume of paste in the heat slug area
> is lifting the
> part up and surface tensions take over.
> 
> I have a call into tech support at Phillips, but I figured I would query
> while waiting for a call back.
> 
> What is the recommended volume of solder paste under this device ?
> 
> What is the recommended solder mask opening(s) under this device?
> - Something like 4-6 smaller opening over a continuous top side
> ground plane?
> 
> What is the recommended paste printing pattern under this device?
> - match the soldermask openings?
> 
> Does anyone have experience with such a device?
> 
> Thanks,
> 
> Dave
> 
> 
> --
> Dave Seymour, CID+
> Catapult Communications Inc.
> 800 Perimeter Park Dr, Suite A
> Morrisville, NC 27560
> 
> Direct: (919)653-4249
> Main: (919)653-4180
> Fax: (919)653-4297
> 
> [log in to unmask]
> 


-- 
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