Converter boards are back and I cut some stencils!

Laser Converter V1.1 PCB

 PCBs are back from the fab! I'm going to spend the next few days building up boards and shipping out assembled units to those who per-ordered. Once all orders have shipped, I will place the rest up for sale.

To speed up the assembly process, I decided to try to laser cut out a solder paste stencil for the new converter boards.  

Stencil cut on Chinese laser cutter

Using Cambam, Mach3, and Chris' Circuits laser converter board, it is SUPER easy to get a Chinese laser cutter to cut a paste mask stencil.

I bought a pack of 5 mil (0.005") thick mylar sheets from e-bay to use as the stencil. 5 mils is probably a little thicker than what you'd want when making a solder mask stencil but I thought I'd give it a try. Once you have your PCB designed in the layout software of your choice, all you have to do is export the solder paste layer gerber file like you would normally do when fabricating PCBs. Cambam will import .gbr extensions natively. Once you get the .gbr paste mask into CamBam you can either choose to cut the paths using the engraving or profile methods of machining. If you choose engraving remember the cut will always cut on the line. You can't easily make changes to the size of the features using engraving. If you want to select a cut width (tool diameter) or easily shrink the size of the features you will want to use a profile machining operation. When using the profile operation you will need to choose a non-zero target depth to have the Gcode created correctly. Once you have a target depth choose to have the cut on the inside or outside and the tool diameter. I found that my laser was cutting a 4 mil cut. So if I set my tool diameter to 4 mils I should get my features exactly as defined in my paste mask. Because my material is thicker than standard stencil material, I may want to shrink my features. To do that I can define my tool diameter to be something larger. When you generate the tool paths you can see how you features have changed size based on tool diameter. I will be using these stencils a lot in the next few days and I will post an update with results.