Steve,
I agree the manufacturer should be the primary source.
In the this particular case ( pun intended), It depends.
The Phillips site varies depending on package.
In the document listed, BGA Geometry :
http://www.semiconductors.philips.com/acrobat_download/various/Surface_mount_reflow_soldering.pdf
Recommends 20%-35%, as mentioned.
In another document, different package (DWFN):
http://www.standardics.philips.com/support/documents/logic/pdf/dqfn.solder.pdf
Recommends 80%
As far as the original question, with a So8 heat slug package, I'm
waiting on Phillips to get back to me.
I talked to our Contract Assembly house to get their opinion. The CM's
opinion was closer to the 70-75%
coverage.
The line of thinking is the same, reduce the volume of paste for heat
slug devices. The amount of reduction
is package and process related. Work with the assembler to refine the
process for consistent results.
Thanks to all who responded.
Dave
Steve Mikell wrote:
>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]
>>
>>
>>
>
>
>
>
--
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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