--- In
Homebrew_PCBs@yahoogroups.com, Ronald Vanschoren
<yahoogroups@...> wrote:
>
> Hi all,
>
> I've just had my first try at making a PCB and it failed :-(. Could you
> guys (and girls) please look to my procedure and correct me if I did
> something stupid.
>
> I am using the kit from Conrad (
>
http://www.conrad.fr/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&storeId=10001&productId=209546&langId=-2&parent_category_rn=18950 > ), which consists of a black box containing 4 UV tubes and a heated
etch
> stand.
>
> I've designed a test board using eagle and exported it as an image (
see
> www.lieron.be/pcb/small_2400dpi.bmp ).
> I've printed the pattern on a transparent slide using a inkjet printer
> (Canon Pixma 5400R), with all settings to "darkest" and highest
quality.
> It came out very well..
> Then I put the transparent on the glass plate in the UV box and
placed a
> piece of photo sensitive PCB on top of it. After 2.5 minutes of
lighting
> I developed the PCB in a NaOH solution (1 liter for 35grams NaOH).
> You could quickly see the process failed then, the pattern didn't show
> up, only the big black spot and the widest track were somewhat visible.
> I've tried several other light times, from 1.5 minutes to 3 minutes but
> they all seem to give the same result, the small tracks are gone
every time.
>
> I've also tried putting a second identical transparent on top of the
> first one to make it darker but that didn't help either. The weird
thing
> is I taped the second one using regular green DIY tape and that seemed
> to stop the UV light better then the much darker transparrent. Could it
> be an issue of the inkt not stopping UV light?
Yes, very likely. Black in visible is not necessarily opaque in other
bands.
Thoughts and subsequent experiments by someone on Screenprinters.net
found that using the light cyan and yellow to print for UV exposure
worked better than black. Reasoning: those two inks are the most prone
to fading due to UV damage. So those are the inks that have had the
most work done in blocking UV to make them last longer.
Since you cannot choose exactly which inks to use to print, you could
experiment with light green shades and some testing. Or sacrifice a
printer by loading a mix of light cyan and yellow into all the cartridges.
An alternative is to bop on over to screenprinters.net and find out
which brand of black inkjet ink they are using, as most are using a
particular brand of black ink (not necessarily all the same). That
website is sponsored by a company that sells RIP software for
screenprinters, I think they also sell their own ink just for this.
Steve Greenfield