Use a plotter, and have phototools made using a bromide camera.
On 21/6/2010, "boombox666" <boombox666@...> wrote:
>Hello everybody,
>
>Just this weekend I finished up my CNC drill robot and it is happily drilling away. After checking positional accuracy and axis alignment I am quite satisfied. Deviation on X and Y axis are 150 micrometre over a distance of 20cm. Angular distortion of the X and Y axis on a 20 by 20cm square the distortion is about 300 micrometres.
>
>Pretty good for generic stainless steel threaded rods.
>
>But now I have a problem with my transparencies, they seem warped, the holes on the transparencies do not register on my predrilled PCB. This would not be a problem if the variation was uniform. But no such luck...
>
>I have printed out an hole grid of 1 centimetre. It seems to deviate a few 100 microns positive in some spots, but other spots it is about a few 100 microns negative. This is mostly on the long direction of one A4 sheet. The short direction is more or less the same warping and it seems uniform.
>
>Does anybody have any idea on how to proceed? Does anybody use photo exposure combined with CNC drilling? What printer do you use to print out the PCB layout? What do you print out on? What kind of transparencies? Do you need to compensate for any warping of the printout? I am currently using a canon laser printer MF3110.
>
>I have been thinking about a home-brew solution. Constructing a raster scanner with a blue-ray laser and directly expose the PCB. Takes some work but the resolution seems very good (I have seen it pass by on one occasion).
>
>Any help is greatly appreciated.
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>