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I've tried making my own solder paste stencil using 4 mil polyester (for overhead projection slides) on a 45W Epilog laser cutter at the local TechShop maker space. I could not "cut" the stencil cleanly, because the edges charred and became uneven. I had some more success with "etching" the stencil, but the solder paste application still had a lot of slop around a 0.5mm TQFP footprint (generating several solder bridges.) Meanwhile, when I used a stainless steel stencil from Advanced Circuits, for the same footprint and paste/applicator, the imprint was super crisp and no solder bridges.

I know that others are successfully applying solder paste with polyester/mylar based stencils from places like Pololu or OSH Stencils. Given that I have access to a laser cutter, I'm thinking there's got to be a way to make them on my own, and probably the problem I had was that I used an inappropriate film/material. However, researching online, I can't find any material specifically billed as being good for this kind of work -- so, does anyone have experience to share on particular materials for laser-cut stencils? Part numbers or at least specific brand/model names would be great!

EDIT in October 2016: OSH Stencils now offers affordable steel stencils, so making my own is much less desirable. I highly recommend steel over plastic!

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  • \$\begingroup\$ I've heard that other laser-cutting shops offer Mylar or Kapton stencils. \$\endgroup\$ – Ignacio Vazquez-Abrams Mar 5 '14 at 0:26
  • \$\begingroup\$ I just use pcb-pool and click the "free stencil" box for a free steel stencil \$\endgroup\$ – Scott Seidman Mar 5 '14 at 1:13
  • \$\begingroup\$ @IgnacioVazquez-Abrams FWIW, Mylar and Kapton are DuPont trade names. The generic names are polyester and polyimide, respectively. \$\endgroup\$ – Spehro Pefhany Mar 5 '14 at 2:09
  • \$\begingroup\$ Scott: Three 47x47mm boards with a stencil at pcb-pool are $177 plus shipping from Europe. Three 47x47mm boards at OSH Park, with shipping, is $17, shipping included, and an Advanced Stencils steel stencil is $99. I'm looking to LOWER costs, not raise them! \$\endgroup\$ – Jon Watte Mar 6 '14 at 1:24
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    \$\begingroup\$ I doubt you'll find plastic that will work like metal. My experience with metal stencils is that it spoiled me. Its basically impossible to hold plastic flat like metal. I have used the transparency material successfully on a cnc router. Have you tried different power settings? \$\endgroup\$ – Erik Friesen Mar 17 '14 at 12:00
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As you noted, at Pololu, we use Mylar for our Laser-Cut Mylar SMT Stencil service. It's not that hard to find Mylar films: McMaster has a bunch of them. Take a look at McMaster part number 8567K32. (Sorry for not linking, McMaster is hard to link to.) The main trick is carefully tuning the cutting settings and design to account for the quirks of your cutting process. We use internal computer programs we've written to modify the designs to make the cuts turn out well in our process.

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  • \$\begingroup\$ That's a great reference, thanks! Running the same plot through a number of times to tweak the output wouldn't be that bad. \$\endgroup\$ – Jon Watte Apr 6 '14 at 5:01
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The other great material for making stencils is Kapton. It is very hard wearing (multiple paste applications) and heat tolerant (so cuts instead of burning under the laser), also rather dark so good at absorbing heat from the laser.

There is a how-to on using a Trotec Speedy 300 (85W) with it here.

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  • \$\begingroup\$ Thanks for the suggestion. The How-To seems to be a generic manufacturer information page, which only mentions cutting plastics in general, and does not address any of the specifics I'm requesting help for, though. \$\endgroup\$ – Jon Watte Nov 29 '14 at 5:59
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Give OSH Stencils a try, I think you'll be impressed with their quality. They offer 3mil and 5mil stencils, and for ultra precision we use their 3mil stuff frequently and it's really good. The price is hard to beat and the process is painless on their website.

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    \$\begingroup\$ This doesn't really answer the question, which specifically mentions OSH Stencils but says he would prefer to know how to make his own. \$\endgroup\$ – David Mar 27 '14 at 8:23

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