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| Date: | Tue, 26 Oct 2004 19:39:05 -0500 |
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Jason, did both solder pastes have the same flux chemistry?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Daan Terstegge
Sent: Tuesday, October 26, 2004 4:00 PM
To: [log in to unmask]
Subject: Re: [TN] Question about 2% Ag and stencil release
Hi Jason,
I don't believe this has anything to do with silver.
The fine powder of your type 5 paste has a MUCH larger ratio between
soldersurface and soldervolume than the part 3 type, which means that it is
more difficult to keep the powder particles stable and oxide-free. The
smaller process window increases the chance of printing problems.
Hopefully a more accurate description will be given by one of the paste
manufacturers on this forum, but I think I'm pretty close....
Best regards,
Daan
http://www.smtinfo.net
----- Original Message -----
From: "Jason Gregory" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, October 26, 2004 9:44 PM
Subject: [TN] Question about 2% Ag and stencil release
> Has anybody had any experience or seen/written studies involving 2% Ag
> release from stencil apertures? We have a stencil, parts are small
resnets,
> about 15 mil pitch on a .006" thick stencil. Tried 2% silver paste (for
> tombstoning of other parts) with type 5 powder and had major release
> problems. We kept the same parameters on the screen printer (for
> reference/control purposes) and swapped in our "normal" 63/37 Type 3
powder
> and release issues "virtually" went away. Not all the way, but for the
most
> part. I thought smaller mesh should have meant better release. Solder
> gurus ------- enlighten me!
>
> Jason Gregory
> Manufacturing Engineer
> Innova Electronics
> (281)653-5593
> (281)653-5594 fax
> (281)310-7588 cell
> [log in to unmask]
>
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