Howard, in the past, I was forced to use to use and invest in smaller, less expensive systems (I've since been lucky to have nice EXPENSIVE toys-teehee). One of my favorite tools has always been the benchtop Cyberoptics unit. I don't remember the model name, I'm sure it's on their website, or a price figure. But I do know it was cheaper than most systems.
The beauty of it is it shoots a laser at an angle, laser is viewable on monitor and is deflected by paste height. You line up the reference lines on the screen and get pretty true paste height. If your using 1:1 apertures or if you're doing aperaure reductions, you can calculate your volume.
Hope I've helped.
Jason Gregory
SCI Systems, Inc.
Software Specialist - NPI Group
(256)882-4107 x3728
[log in to unmask]
>>> [log in to unmask] 07/31/01 11:49 AM >>>
Hi Howard,
I've always found measuring solder paste volume to be very difficult. Yes,
numbers can be generated, but even taking large amounts of data doesn't
guarantee the correct impression. Generally, regardless of equipment used,
the best results one can hope for are for trends, which at best could be
described to be of the order of -1 or +1 from true. It's not a bad thing to
try but don't expect absolute results.
Best regards,
Andrew Hoggan
BBA Associates Ltd
www.bba-associates.ltd
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Howard Watson
Sent: 31 July 2001 14:47
To: [log in to unmask]
Subject: [TN] Solder Paste Measurements
Dear Technetters,
My question is: how do you measure solder paste height and volume
accurately? My situation is with using the VisionMaster Model 150A, I am
having trouble obtaining reasonably accurate measurements. The VisionMaster
is a small bench topsystem that uses a template consisting of a "region of
interest" (the solder paste), and reference regions (the areas on each side
of the pad). Because there are inconsistencies in the PCB (HASL finish),
like raised areas from traces, valleys surrounding the pad, and
irregularities in the solder mask, the readings I get cannot possibly be
true. Many times the measured readings for weighted average height are over
7.5 mils using a 6 mil screen and 9.5 mils using an 8 mil screen. The
process specifics are Multicore NC-40 paste, shore 94-97 polyurethane
blades, DEK 265 Infinity, and correct squeegee pressures, print gap, etc..
I believe the bricks are good, I just ca! n't use the measurements for SPC
as it shows the process to be out of control.
In theory, polyurethane blades should "scoop" if anything, leaving a
shorter brick than the stencil thickness. It seems logical to me that the
best way to obtain accurate measurements would be to use the pad as a
reference region and measure the height from the pad, but the VisionMaster
system does not allow me to do this. Does anyone have knowledge or
recommendations on what I can do here? How do the more expensive systems
measure solder paste? Oh yea, spending $$ on new equipment is not a real
good option at this point!
Thanks in advance for the assistance,
Howard Watson
Manufacturing Engineer
AMETEK/Dixson
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