🚀 go-pugleaf

In article <76416@apple.apple.COM> apn@Apple.COM (Alex Novickis) writes:
>In article <1993Jan10.225053.28590@phx.mcd.mot.com> schuch@phx.mcd.mot.com (John Schuch) writes:
>>I, to, have had this problem once in a while but have found most 
>>cameramen pretty darn accurate. Another thing I ALWAYS do is include
>>a rule in the artwork. Something like this:
>
>With current laser photoplotting technology, WHY ?? whould you want to 
>do reductions ?? LP's can generate things much finer than you can
>ever hope to etch.... I think that's about 4 mil traces with 4 mil
>seperations. And it usually costs me under 10$ for a 10x10" film (OK, 
>well I do need several of them... but still)
>

- Because if all you have is printer output with marginal quality 
  (contrast), 2:1 or better 4:1 traces will appear darker to the film.

- Because you can see defects in 4:1 art much easier than you can in 1:1.

- Because some people still use tape on paper for the master artwork.

- If you use a 300 dpi printer to make your 1:1 artwork, your film will
  be 300 dpi. If you use a 300 dpi printer to make 4:1 artwork, your
  film is effectivly 1200 dpi. I don't know if it's measurable but I
  can just see fuzziness on diagonal lines etched from 300 dpi film.
  Given the variabilities in the at-home etching process, I want my
  film as absolutely perfect as I can make it.

- Because it makes the process seem more complicated, and hence, more
  impressive to the in-laws.  :-)

The absolute bottom line reason? I'm more comfortable with it. You are
correct of course that 1:1 artwork from a laser printer will provide
perfectly good film. I just prefer the added safety margin.

BTW: I've tried several of the laser-to-transfer sheet-to-pcb-etch
products ( ie. TEC-200 ) and have not have good enough results to
justify getting rid of the lito-film/expose/etch method.

John
(Anybody see the segment on CNN about internet smiley faces :-) )


John


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| John R. Schuch  -  Motorola Computer Group  -  Manufacturing Engineering |
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