On 31 January, Mike wrote:
> Can anyone reccommend a manufacturer of a device that measures
> the height of solder paste after it is applied to the board.
Thanx Ahead
Hi Mike!
There's a BUNCH of companies making equipment to inspect or measure solder
paste height. You can go "whole hawg" and pick up a Four-Pi or View Engineering
3-D X-Ray machine for a measly half-a-million clams or so, but for some reason I
get the feeling that you're not looking for something quite so elaborate.
I've got experience using equipment from three vendors that make off-line,
non-contact height measuring units...you gotta' take the printed PCB to it to
measure the paste. They are: CyberOptics, Vision Engineering, and Screen
Manufacturing Technologies (now a division of Alpha Metals since they bought
them). The cost of the equipment ranges from around $14-15K for the CyberOptics
LSM, to around $1,500 for the SMarT Measure from SMT. The Vision Engineering
unit sells for around $10-12K.
The acurracy of measurement guaranteed by all three is plus or minus a
half-a-mil. So depending on what you wanna' spend, pick your poison...any of the
three will give you the same measurement, albeit some will give it to you in a
little fancier way than the others will.
Now for my own take on the whole issue. Solder paste height measurement to
me, is most important at the printer set-up in my eyes. If we're spending in
excess of $200,000 for a screen printer, it damn well better be able to give me
decent, consistent prints without having to check every one, or even one every
hour. If I can't set-up the printer, keep enough solder paste on the stencil,
and clean the bottom of the stencil once in a while and not have to worry about
measuring the solder paste height all day long, something really is wrong!...and
I don't think measuring the height of the solder paste all the time is gonna'
help too much. BUT, checking the height at printer set-up is another story.
The SMarT Measure is a depth measuring microscope, the same technology that
Vision Engineering uses. Basically it's a 100X microscope mounted on a platform
and postioning arm, that has a Mitutoyu (I think) digital micrometer attached.
You position the PCB beneath the microscope where you want to measure,
focus on the top surface of the pad, zero the micrometer out, and then re-focus
again at the top of the printed paste. Then you read the height on the LCD
display of the micrometer. You can get an optional printer that plugs into the
micrometer that has a little SPC program in it and it will do the calculations
for a set number of measurements for you, and give you a SPC print-out.
You can also get measuring reticles for the microscope to do X/Y measurements,
which are good to measure pad, lead, or stencil aperture dimensions.
So as you may have gathered, I kinda' like the SMarT Measure, (for only
$1,500 dollars). I just can't see paying 14-15 grand for something to measure
solder paste height with...I don't know, maybe it's just me...
But the numbers for all three vendors are:
Screen Manufacturing Technologies (408) 562-2033
Vision Engineering (714) 974-6966
CyberOptics (800) 746-6315
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