1 watt infrared laser cutter not cutting all the way through

I just modified my diy cnc with a 1 watt laser for cutting pcbs. That is, I spray a copper clad board with black plasti-dip spray which forms a layer which resists etching by chemicals then laser away the parts that will be etched. THe plastidip spray however is not getting cut all the way. THere is a very clear line where it is burned but it refuses to completely remove it. When I peel the plastidip off of the board it cuts right through it in a milisecond. I'm not sure how I can make this work. Any suggesetions? (besides get a stronger laser ) Even leaving it one spot for several minutes does not cut all the way through when it is on the copper.

The intensity is probably not enough to vaporize the material, thus leaving a bit of char left over that refuses to go anywhere. What lens system are you using? I would suggest going to a shorter focal length since DoF is obviously not an issue with such a thin coating.

Also, I don't know that 1W is enough for your needs. I can do that kind of work with my 15W CO2 laser, and it just barely is enough when properly focused to totally evaporate material.

Yep, the copper is acting as a heatsink. The 1W laser is more melting it's way through, you need a laser capable of vapourizing it's way through

Ok I was afraid of that :/ would a 2 watt blue laser do it do you think? It doesn't have to completely come off exactly. If I could rub it off without removing the rest it would be ok. As for the copper acting as a heatsink would heating the board up help?

I doubt you'll be able to achieve the results you want using any diode based laser. The higher power multiwatt diodes are all multimode emitters which cannot be focused down to a tight enough spot to achieve vaporization, especially with a heatsink backing involved.

Heating the plate won't help any. VERY high power is typically used for this type of work industrially. You might be able to get a burnt enough char that you can scrape it away with a wire brush or something, but then at that point what is the benefit of using a laser?

Hmm that's depressing. But thank you for your help. I'll look into a full co2 laser

ghostbust555 said:

Hmm that's depressing. But thank you for your help. I'll look into a full co2 laser

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A sealed 80-100W CO2 laser tube might be what you'd be after. It'll require a HVDC source, a cooling system (water pump) and optics.

Looking at ~$500 just for the tube.