How to make an Eagle Solder Mask Stencil for an Laser Cutter


There is a hardware hacking class that qlabs is presenting over at hacdc.  My friends over at theQlabs asked if I could whip up a solder mask stencil to aide with soldering the SMD portion of the GoodFet hardware they are using.  I went ahead and did so..  I also took some screen shots to demo the process for everyone.  So this is how I do this.
Everything you need to create a good solder mask is built right into EAGLE PCB.  The first thing we do it download the goodfet21.zip EAGLE files.  We open the BRD file (you might be able to use the GERBER files but this is how I do it) and Hide all layers.

 

Step 1

Hide the all of the layers.  Then display only the Dimension and Tcream.  (Note: in the screen shot its the document.. it needs to be Dimension).  Also change the fill style for the cream layer.  It is a “hatch” looking pattern by default.  We want a solid color pattern.  I left the color Grey.  When we print the PDF it will turn it black anyways so it does not matter. Click ok.

Now you need to click Print and then click the PDF button.  This is going to get us a vector format of the stencil.  However, for some weird reason the PDF writer in EAGLE creates some sort of non-standard PDF (not sure exactly).  This does not allow us to just import this into Corel Draw (corel is what the vector cutting drivers work  for the epilog laser cutter).

So scroll down to see the next step.

Now you will need to download Ghostscript and Gview for your platform.  Here is the windows links.
http://mirror.cs.wisc.edu/pub/mirrors/ghost/GPL/gs864/gs864w32.exe – Ghostview
http://mirror.cs.wisc.edu/pub/mirrors/ghost/ghostgum/gsv49w32.exe – Gview (Windows GUI for Ghost Script)

Ok once those are installed go ahead and open Gview and then open the PDF we created above.

Now click File >> Convert.  Select the EPS Write and type in 1200 dpi.  Then click OK and save it. You now have the file you will be loading into the epilog laser cutter.

Open up Corel draw… Ungroup everything (if needed) and check the outside lines for duplicates.. Meaning select a outer line and delete it… If you see another line.. Delete that one until the lines are no more.. Then just undo the last delete.  Why do we do that?  For some reason Ghostscript from time to time adds multiple lines on the outside.. Not sure why.  But if we do not delete them we will have the laser cutter going over everything (at least the outter edges) 2x or 3x.  Ok so you have removed all duplicated lines and now you are ready to select all and make the line width a “hairline” width.  This is something that corel calls it.  This is the #1 reason that you can only use Corel draw to do cuts (vector stuff) with the epilog.  So anyhow.. Now you should print it out.  Setup your desired epilog settings (based on your material) and have at it.

Your done!   (DFX is here: Goodget 2.1 stencil dxf)

Goodfet Solder Paste Stencil


Comments

  • Will be using this in Q’s class. Awesome results – thanks for working on this and publishing the howto!

    obscuriteMarch 18, 2010
  • np!

    Ril3yMarch 18, 2010
  • That’s awesome! I’m jealous of your laser cutter. (and your whole workshop as well ;-)

    (Fyi… it looks like you might have duplicated the first two paragraphs in your post).

    Chris.W.Zeh@gmail.comMarch 18, 2010
  • Awesome man! Added to our project page: goodfet.sourceforge.net – thanks again man, will help with the soldering process for my course.

    QMarch 18, 2010
  • March 19, 2010

    [...] 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 [...]

  • Cool, thx limor. I will have to check out your method. I know about kapton. However I found that for hardware classes I can use a heavy card stock and pump these out pretty cheap and they work pretty well for about 3 of 4 boards each.

    Ril3y

    Ril3yMarch 19, 2010
  • It seems to me that you’re not making full use of the capabilities of EAGLE. For instance, using the CAM processor, you should be able to export tCream directly to EPS (though not in vector form), and EAGLE also has some ability to generate outlines of layers (though perhaps only signal layers.) And then there’s the possibility of creating a custom CAM output device (based on EPS) that would do outlines only. In general, if the goal is EPS or PS that contains only edges of the relevant layers, it seems like it ought to be possible to do it in a lot fewer steps… PM me if you want to experiment (I don’t have access or knowledge of the laser cutter.) (OTOH, you have something that works so perhaps it shouldn’t be messed with…)

    WestfWMarch 19, 2010
  • Hi can you send me your drawing in DXF for me to try it in my Watherjet pls..

    DrLabel

    DrLabelMarch 19, 2010
  • I attached the dfx file on the main post in a zip file.

    Ril3yMarch 19, 2010
  • This was bugging me, so I went further with it…
    Try putting this at the end of your eagle.def file:

    [laserstencil]

    @EPS
    Long = “Postscript with 0-length lines for laser cutter”
    Header3 = “/b { %% draw a bar\n”\
    ” /an exch def\n”\
    ” /y2 exch def\n”\
    ” /x2 exch def\n”\
    ” /y1 exch def\n”\
    ” /x1 exch def\n”\
    ” /w2 x2 x1 sub 2 div EU def\n”\
    ” /h2 y2 y1 sub 2 div EU def\n”\
    ” gsave\n”\
    ” 0 setgray 0 setlinewidth\n”\
    ” x1 x2 add 2 div EU y1 y2 add 2 div EU translate\n”\
    ” an rotate\n”\
    ” newpath\n”\
    ” w2 h2 moveto\n”\
    ” w2 neg h2 lineto\n”\
    ” w2 neg h2 neg lineto\n”\
    ” w2 h2 neg lineto\n”\
    ” closepath stroke\n”\
    ” grestore\n”\
    ” } def\n”

    WestfWMarch 20, 2010
  • March 20, 2010

    [...] H&#959w t&#959 m&#1072k&#1077 &#1072&#1495 Eagle Solder Mask Stencil f&#959r &#1072&#1495 Laser Cutt… [...]

  • March 20, 2010

    [...] H&#959w t&#959 m&#1072k&#1077 &#1072&#1495 Eagle Solder Mask Stencil f&#959r &#1072&#1495 Laser Cutt… [...]

  • Tks

    DrLabelMarch 20, 2010
  • WestfW I will go ahead and try it out. Once I place that in my def file what is the “action” that I need to do to get this script to execute?

    Ril3yMarch 20, 2010
  • Definitely, use .eps format option. You can use this format for either raster scan or vector cutting.

    ohararpMarch 20, 2010
  • After patching eagle.def, use the CAM processor. Select tCream and Dimension layers, device “laserstencil”, appropriate output file, and click “process job.”
    This of course can be saved as a “cam job” or added as an additional step to an existing cam job. And the CAM processor is EAGLE’s “dimension accurate” output mechanism, with no printer drivers to confuse things.

    WestfWMarch 20, 2010
  • March 21, 2010

    [...] 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 [...]

  • I’ve used a similar technique before, but I did one or two things differently:

    1: It looks like you’re vector cutting the holes. I found that I had better precision when I raster cut the material. Something about the way that the epilog’s do corners in vector mode… they seem to slow down to take a turn, but don’t lower the laser power to match.

    2: I gave up on paper-like material. I found that one or two layers of packing tape worked really well. The trick is that it needs to be stuck to a sheet of metal when you cut it, so that the metal absorbs much of the heat. Otherwise, you end up melting the tape completely. The packing tape was nice, as it stayed ‘stuck’ while you apply paste.

    If you want to see pictures of what I did:
    http://wiki.cc.gatech.edu/ccg/making/lfbgasolder

    Scott GillilandMarch 21, 2010
  • For my epilog laser needs i actually print straight from PDF. Adobe Reader seems to be able to print raw postscript. In my svg files that I use as inputs I just specify the “0.001in” or 0.072 points for line width to do a vector cut.

    Curtis RuckMarch 21, 2010
  • @Curtis:
    Wow that works? I have yet to be able (granted I tried in inkscape) to get anything to print vector cuts outside of corel. Do you have a blog on how you are doing it? I would love to read it :)

    Ril3y

    Ril3yMarch 21, 2010
  • I discovered today a way to cut 0.5mm pitch solder paste stencil with a laser cutter, by water-cooling the plastic. If you just cut the mylar, it can melt the tiny strips between the pads. But if you put the plastic on a wet piece of paper, the laser still goes through, but it does not melt beyond the beam, and the edges are very clean.

    I used a thick scrap piece of acrylic as a base, put a piece of ordinary laser printer paper on it, poured on a bit of water, put the 2 mil mylar on that, and then smoothed it out and blotted up the excess water. You want the water to get on both sides of the paper and soak it through.

    On an Epilog (45 W? I’m not sure; it’s one of the TechShop Menlo Park laser cutters), a vector speed of 50, power of 10, and frequency of 5000 was more than enough to cut through the mylar… but not melt it. It works on both 2mil and 6mil. I shrank all the pads by 6 mil, but I’m not sure you have to… it worked well enough that I did hardly any tuning of the process.

    Chris PhoenixAugust 31, 2010
  • Chris,

    Cool trick. Yah I had issues with doing vector cuts so I just used a raster engrave option. However this is much slower. Next time I create a board I will def try that option.

    Ril3y

    Ril3yAugust 31, 2010
  • To cut vectors on an Epilog from Inkscape, set your line widths to 0.01mm, then save the file as pdf.
    Print the PDF from Adobe Reader as usual.

    thinkl33tSeptember 30, 2011
  • thinkl33t:

    Cool I will give it a go!

    Ril3yOctober 4, 2011
  • I know this post is pretty old now, but I stumbled upon it on google, and thought I’d chime in.

    I own a 35W epilog laser cutter. You can indeed do vector cuts with other programs besides corel. In fact, I never use corel for anything. I normally use Illustrator for all vector cuts, and some raster engravings. I use photoshop for the remaining raster engravings.

    In order to get the laser to vector cut a line, simply set it’s thickness to .001in.

    You can also check if it is working very easily – simply send the job to the laser cutter, turn the pointer on the machine on (so you can see the red dot indicating the laser’s head), and run the job with the glass cover open. If the cover is open, the job will run, but the laser will not be powered up, and you can see if it is correctly tracing the lines.

    If the print job ends immediately, then the line thickness is too thick (assuming you printed on vector mode and not combined vector/raster)

    KevinJanuary 5, 2012
  • I dint know that those steps will actually work. Well, I guess I’m just too lazy to figure it out. And these steps just helped me out. And yea, MATH!

    Lisa KeenJanuary 22, 2012
  • Hi there!
    I’m just wondering if there is a path, or logic, that a laser cutter follows when cutting materials.
    I put some texts (vector/outline) and it didn’t follow the way I’ve typed, even in single words!
    I asked our technical staff but they didn’t know.

    taraMay 21, 2012
  • What type of laser cutter are you using? There is on epilog. Kind of. There obviously a path that internally the “print driver” implements. Which to my knowledge is opaque. (not disclosed) However there is a setting to cut from the “inside out” in the print options. This is about as much control as you get in a normal print. However there is the option to do color mapping.. check this out.. a bit more “control” on what gets cut first.

    http://www.epiloglaser.com/tl_vector_color_mapping.htm

    Ril3yMay 21, 2012
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