The thinnest stencil we have laser-cut in stainless steel was 1.4 mil. It
requires extra care in production and some "breath-holding", but it is
doable. Two mil stencils are not a real problem.
Regards, Ahne Oosterhof
A-Laser, Inc
(503)641-9428

PS: The thing about aperture ratios of 1.5:1 is a SUGGESTION and it says:
                Don't make your apertures smaller than 1.5 times the metal thickness.
So when the stencil is going to be 6 mil thick, try to keep the minimum
dimension of your apertures larger than 9 mil, but with a well-cut stencil
together with an experienced printer technician you can go well below this
suggested minimum. For a 2 mil stencil you could go to 3 mil apertures using
that rule. (There is also this suggestion that you should be able to fit at
least 5 solder balls next to each other in the aperture!!) But when you are
asking about 2 mil stencils, I expect you have a special reason to go that
thin, not just the nice small amount of solder paste.
Have fun.

One more answer:
The trapezoidal shape of laser-cut apertures results from the shape of the
focussed laser beam and the melting and flow pattern of the liquid metal. It
probably depends on the type and brand of laser you are getting your
stencils from, but I see a typical size difference between the top and
bottom of the stencil of about 0.2 to 0.4 mil. By carefully adjusting the
focus setting of the laser you can change this property somewhat. The entry
opening in the metal is typically larger than the exit opening, which is why
almost all stencils are cut from the contact side rather than the squeegee
side.



-----Original Message-----
From:   TechNet [mailto:[log in to unmask]] On Behalf Of joyce
Sent:   Wednesday, September 22, 1999 16:07 PM
To:     [log in to unmask]
Subject:        [TN] thinnest stencil

What is the thinnest laser cut stencil exist on market?  4 mils? 3 mils? 2
(I think someone is going to tell me "get lost")...
Many thanks in advance...
                               jk

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