Laser cutting solder stencils

Do you have access to a laser cutter? If so, you can use [Riley Porter's] method to cut your own solder stencils. He starts with the Eagle files and exports the Dimension and tCream layers to a PDF. That file is then processed using Ghostwriter, Gview, and finally, Corel draw. The result is a 1200dpi file to feed to your Epilog laser. Now you’re ready to stencil on the solder paste and populate the PCB.

[Thanks Travis Goodspeed]

Comments

  1. mrgoogfan says:

    i wonder if the money saved outweighs the cost of a laser cutter….

  2. cd0 says:

    …or you can send pololu the DXF: http://www.pololu.com/catalog/product/446 The mylar isn’t the most durable, but you can’t beat the price.

  3. macegr says:

    These instructions are partially wrong…I’ve been cutting stencils from Eagle files for about a year. He’s right about the Eagle PDF export causing problems, I’ve been using Inkscape to open it and save in a format Corel understands.

    The main thing he’s wrong about is the actual sizing of the cream outlines. You can see a lot of his pads actually overlap, this will allow too much solder to be deposited and cause bridges during reflow. Due to the kerf left by the laser cutter you need to shrink the outlines by a few mil. I usually go into the DRC Mask section, and on the Cream part I set a max of 10mil and a percentage of 20% or so. Then export the cream layer.

    For 2mil mylar on a 45 watt laser, I tape the plastic on smooth birch plywood and cut the outlines in vector mode with 8% speed and 3% power. That seems to eliminate most of the melting and rough edge problems people complain about with mylar. It actually sticks most of the chads to the plywood, so when you pull off the stencil it automatically weeds most of them.

    Here’s a picture of one stencil I made: http://www.flickr.com/photos/macetech/3311194156/

    And here’s a video of cutting a stencil recently: http://www.twitvid.com/5F80B

  4. Maverick says:

    I usually use raster mode to obliterate the mylar , works best for me

  5. Paul says:

    This is going to be exceptionally useful, given I have access to a laser cutter and do lots of SMD work. I’ve always wanted to try to make stencils on the lab laser cutter, but this is a good head start.

  6. Ken says:

    This is interesting, If I wanted to build a rig to laser cut parts would I just use the standard X Y plotter design? and what type of laser will I need for cutting?

  7. We’ve been figuring out how to get extremely fine pitch stencils on kapton (polyimide) film out of our laser cutter, and have found that you need to not only adjust the cream layer, but you need to adjust the aperture of your gerber as well, depending on how the beam of your laser cuts.

    It’s fairly straightforward in principle, but like most things, it takes a bit of practice.

    Details are here.

    http://wiki.metrixcreatespace.com/laser-cutter

    • Dave Thomas says:

      Great detail, Mat. Thank you!

      Is there any reason to use Eagle’s DRC Masks if the Gerber apertures need to be tweaked anyway?

      I figured I’d write a simple script to change the ADDR,X* as you suggested and just include the size decrease for the kerf there. Then use gerbmagic dll to write a pdf file that can be imported into Corel for printing to the Epilog laser.

      How big is the “wide Y, narrow X” effect? I think you’re saying that’s caused by the laser itself, not in the gerber or eps/pdf file?

  8. Dielectric says:

    For those of us who haven’t talked the boss into getting a laser cutter, there’s this guy:

    http://www.applied-electronics.com/

    For $25, it’s a great deal. I had been getting the stainless-steel stencils from Stencils Unlimited but they get pricey for proto work. $25 is a no-brainer. I used Applied’s kapton stencil for a design with some nasty thermally-enhanced leadless parts and it was perfect.

  9. ril3y says:

    @macegr

    You are right about the laser kerf and the need to shrink the size a bit. However this post was just to show the guys in http://www.theqlabs.com‘s hardware hacking class how I made their stencils. I know lots of people use mylar however I have learned that using a higher grade card stock paper works better. Mylar starts to melt and the edges are not super clean. Mylar is better in the long run for multiple uses (meaning multiple days). But the paper does not melt and edges are 100% straight.

    @mrgoogfan
    If this is all you used the laser for then I would say No… I use mine for alot of different stuff check out my flickr stream.

    http://www.flickr.com/photos/rileyporter/

  10. ohararp says:

    Taking the lead from Pololu and SFE I began to offer kapton stencils awhile ago (www.ohararp.com/Stencils.html). We were the first to offer kapton stencils to the DIY community. We offer $25 stencils and will cut as many stencils as you can fit into an 8.5″x11″ area. We offer 1 day turns on all our stencils as well. This is great for those who need to get their prototypes assembled quickly.

    I highly recommend taking a look at pentalogix’s viewmate. You can “swell” your apertures using their software. I print a .pdf from their software and import this very easily into CorelDraw which runs the laser. Using kapton a 600 dpi raster scan will get you great results.

  11. Dude says:

    Before he has even finished processing the Eagle files, I’ve been pasting up my whole board using the classic syringe method.

    If you need to make many (large) boards, then this would have been faster, but considering a pro stencil cost only $90 for a 24″x24″ frame, why bother.

  12. canongrip says:

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