1 watt infrared laser cutter not cutting all the way through

[ghostbust555]

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.

 

[Sigurthr]

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.

 

[Things]

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

 

[ghostbust555]

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?

 

[Sigurthr]

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?

 

[ghostbust555]

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

 

[Seoul_lasers]

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

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.