Ed, I tried to answer all your questions, hope it helps. See below.
Brad Kendall
Hella Electronics Corp.
[log in to unmask] on 07/14/98 12:21:01 PM
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To: [log in to unmask]
cc: (bcc: Brad Kendall/Hella North America Inc.)
Subject: [TN] solderpaste screen
Hi all,
I have a few quick questions regarding solder paste stencils.
1. What do most of you use as a stencil? I've seen what appears to be a 6
to 7mil aluminum type material when I visit our customers. Is that
somewhat standard.
*6 mil is good. The material is Stainless Steel, this is pretty much the
standard.
2. What is the cost of a typical paste stencil? What could I use a
guideline to determine what one will cost?
*Cost depends on what technology you get. If you do not have fine pitch or
BGA, use chem etch, about $300-$500 depending on frame and supplier. If
fine pitch or BGA is used, use a Laser Cut with electropolish- cost
$600-&1000 depending on apperture count, frame, and vendor. You can also
use Selective etch. This is where they laser cut the BGA and FP parts, but
chem etch the rest, saves a little money.
3. Where can I get them? Is there any located in the Oklahoma, Texas or Mo.
Area?
*You may have a supplier near you, but it is best to go with a reputable
stencil manuracturer and have it shipped. I get my stencils from IRI
INT.at 607-729-4031. I am in Mich and I have had stencils shipped in from
New Jersey (IRI), Colorado, and even California.
4. What process is used to generate the clearances on the stencil. Are they
etched or machined?
*Chem etching is obviously chemicals that etch out the material where the
pads are, laser cut is when they cut the openings with a laser. Laser is
much more accurate and can hold a tighter tolorance, but overkill for non
fine pitch boards. There are also some manufacturers of stencils who use
and additive process. In other words the do not start with a plate of SS,
but rather with a mold and add metal around it for an accurate and smooth
walled stencil. These are generally more expensive then laser and again,
way overkill for non FP assemblies. If you are getting into Micro BGA or
Ultra fine pitch then consider this technology, otherwise don't waste your
money.
5. What are standard lead times for a Stencil. Any help would be
appreciated.
*IRI is next day turn standard on Chem etch, 2 days on Laser. Some others
are longer.
Thank you,
Ed Cosper
Graphic Electronics Inc.
Tulsa OK
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