We take stencils back from customers for frame credit on their next orders.
I have never seen a "used up" stencil come back. From other sources I have
heard use numbers running as high as "hundred thousand" and I have really no
reason not to believe that. At the same time I have seen a stencil that was
literally torn due to excessive squeegee pressure. I also have seen stencils
coined so I could read the copper run pattern and the board outline in the
stencil and I have seen stencils were I could determine the number of nicks
in the squeegee by counting the number of grooves in the stencil. Not to
mention all the other ways in which a stencil can become useless.
So given that you handle the stencil with proper care, use a good squeegee
and that the printer is set up properly, the stencil is most likely to
outlive the board product life.
If not, we can always make a new one :) .
Have a nice Friday,
Ahne Oosterhof.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hal Winslow
Sent: Friday, April 08, 2005 6:53
To: [log in to unmask]
Subject: Re: [TN] Stencil Wear
I have to believe that the single most important factor in determining
stencil life is the skill and care used by the technician when setting up
and running production.
I have replaced stencils because something got dropped on them, or they got
dropped onto something. I have replaced stencils because they were setup
incorrectly, just a bit too much "on contact" printing, so that the stencil
now displays a beautiful topographical map of the circuit board.
I have never replaced a stencil because it was just plain old worn out or
fatigued.
Hal
PS This is of course, referring to the days when I worked in the contract
assy end of things, instead of OEM. Now it is "somebody else's problem."
:-)
-----Original Message-----
From: Morse, Carrie [mailto:[log in to unmask]]
Sent: Friday, April 08, 2005 9:20 AM
To: [log in to unmask]
Subject: Re: [TN] Stencil Wear
The answer to that really lies in the following question:
"How many licks does it take to get to the center of a Tootsie Pop?"
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Leland Woodall
Sent: Friday, April 08, 2005 3:52 AM
To: [log in to unmask]
Subject: [TN] Stencil Wear
Hi everyone,
Can you possibly give me an expected time for the replacement of a 6 mil
laser-cut stencil in a process that uses lead-free paste coupled with
polymer blades? I've had a lot of previous opinions, and few, if any,
match.
How many boards can be printed without fear of the thing wearing out?
I know many variables are involved, such as polymer durometer, aperture
size, etc., but is there a general consensus?
Thanks in advance,
Leland Woodall
Quality Coordinator
Keihin Carolina System Technology, Inc.
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