Hi Cheryl,

How accurate is a stencil? Typically very accurate. The most common and best
laser systems to manufacture stencils allow for accuracies well within 1 mil
and can be used to produce accuracies within 0.5 mil. That means any
aperture can be within 0.5 mil of its intended location. The aperture size
can even be more accurate. But watch out, the intended aperture opening is
the opening at the contact side of the stencil. The opening at the squeegee
side is slightly smaller due to the trapezoidal shape of the aperture walls.
All this presumes the operator knows what he or she is doing!! So I would
not expect you to find a reason to throw away a stencil for inaccuracies.

As we are discussing accuracies, when do you throw away a board because it
is not accurate?

But before you throw away a batch of inaccurate boards, it is sometimes
possible to make a stencil just as inaccurate and allow you to use the
boards anyway.

Did you find any problems to make you ask your question?


Regards,
Ahne Oosterhof,
A-Laser / Fine Line Stencil, Inc.,
Beaverton, OR.
503-641-9428

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Cheryl Tulkoff
Sent: Thursday, April 07, 2005 11:05
To: [log in to unmask]
Subject: [TN] Stencil Accuracy

Does anyone have some guidelines on acceptance criteria for laser cut
stencils? How far from nominal (% or actual) do you allow the stencil
apertures to be before you would reject it back to your supplier?

Thanks, Cheryl

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