Laser-cutting mylar foil

Tags: #<Tag:0x00007f5b75f9e138>

(Robert Kirberich) #1

I will soon have to solder a bunch of circuit boards and I’m looking to laser-cut the solder stencils for them. This would require the use of mylar foil on the laser-cutter, which I think no one has done before here.

@petra this is the project I was talking about today :slight_smile:

Material safety
Mylar is BoPET and seems to be fairly popular for laser-cutting.

If the material is safe to use, the other question would be how to cut stencils with extremely small holes into extremely thin foil.

The smallest holes in the solder stencil are 0.25mm away from each other and 0.25mm wide. The material is 0.075mm thin. Apparently the trick to good results is raster engraving the holes instead of cutting the outline, because that gives the material more time to cool (though to me it seems like just using a very low speed setting should also work?)

I’m finding wildly varying suggestions for settings, ranging from “use very little power and go slow” to “use 100% power and go slow”. The idea with high power seems to be that it leaves the edges much cleaner, but i’d be worried it just spends a lot of time cutting the honeycomb. Here are some example settings I’ve found, which illustrate how wildly recommendations vary:

For reference, this is what the laser would have to cut for this project, the grid size is 1x1mm:

Here’s the only local source of the material I’ve found so far:

I’d love to know what people think about this! I’m hoping it’s safe to use this material on the laser cutter, and if it is - is anyone up for helping me dial in the settings for this?

(Paul Court) #2

Any reason for using Mylar?
I’ve seen stencils done with acetate film (as used in overhead projectors) and I believe that cuts clean + it’s very cheap…


(Robert Kirberich) #3

Not really, I picked mylar because it seems to be the most widely used plastic for this purpose and is used for professional solder stencils. Acetate might also work, and kepton definitely does.

One way to approach this might be to get acetate, mylar and kepton and compare the results, if it’s agreed they can all he safely used.

(Martin Convery) #4

Sometimes it is best to order the cuts so that they don’t cut next to each other, when cutting intricate pieces I’ve ordered the paths so that first path pins 1,5,9 then 2,6,10, stops heat warp

(Robert Kirberich) #5

Yeah that’s a great idea, if the normal cutting strategy leads to too much warping. Definitely a thing to try!

(Robert Kirberich) #6

@lasertechs would you be happy for me to try cutting mylar on the cutter? Do you need any extra info on material safety or would like for a laser tech to be around to try it?