For the finer particle size a slight reduction in metal percent would be
good, but a finer particle size does not actually address your original
concern of release. Smaller particle sizes are chosen to suit deposit
size/volume. What you would have with the finer size is a more expensive
solder paste with possibly reduced process windows. Suggest it would be
preferable to address your printing concerns with the original formulation.
Alloy choice between Sn62 or Sn63 does not affect print performance.
Regards
Mike Fenner
Indium Corporation
T: + 44 1908 580 400
M: + 44 7810 526 317
F: + 44 1908 580 411
E: [log in to unmask]
W: www.indium.com
Pb-free: www.Pb-Free.com
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SMART 6th European Conference, Brighton 16-18 November 2004
www.smartgroup.org/con2004/conference2004.pdf
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jason Gregory
Sent: Wednesday, October 27, 2004 2:42 PM
To: [log in to unmask]
Subject: Re: [TN] Question about 2% Ag and stencil release
Paste was brand new and thoroughly warmed. Metal load on both pastes is
89.5% metal load.
Jason Gregory
Manufacturing Engineer
Innova Electronics
(281)653-5593
(281)653-5594 fax
(281)310-7588 cell
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of David Suraski
Sent: Wednesday, October 27, 2004 8:24 AM
To: [log in to unmask]
Subject: Re: [TN] Question about 2% Ag and stencil release
Daan's assessment sounds right. This could have been a paste dry out
issue.
Jason, do you know what the metal % was in each of these solder pastes?
Best regards,
David Suraski
AIM
-----Original Message-----
From: Jason Gregory [mailto:[log in to unmask]]
Sent: Wednesday, October 27, 2004 9:08 AM
To: [log in to unmask]
Subject: Re: [TN] Question about 2% Ag and stencil release
Yes, same flux in both pastes
Jason Gregory
Manufacturing Engineer
Innova Electronics
(281)653-5593
(281)653-5594 fax
(281)310-7588 cell
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Taheri, Kamran
Sent: Tuesday, October 26, 2004 7:39 PM
To: [log in to unmask]
Subject: Re: [TN] Question about 2% Ag and stencil release
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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