Homebrew PCBs

A year ago or so I started to test multiple printers, transparencies and ink
settings but I got too busy to finish and I am still too busy to continue
right now.  I measured opacity vs. wave length to eventually select the best
combination for creating artwork for photo resist development.

Test artwork:

http://www.vinland.com/USAF-1951.html

Scroll down to the bottom for the PCB test pattern

 

With that as a background, I recently got a new printer and just printed my
standard test print without any tweaking and it looks very promising.  It is
a photo printer and it has three black-gray-light gray inks besides all the
colors..  I have not done any measurements or other tests so no promises.
It also looks like it can print 5 mil lines/spaces.

Printer: Canon Pixma Pro-100.

Regular price $500,  Amazon sells it for $400 with a rebate of $200 and an
extra $50 if one signs up for their credit card.  So at the end I paid $150,
got free second day shipping.

 

As for Phil's comments on lack of laser transparency accuracy would suggest
to use an inkjet instead.  Going through the laser fuser's high temperature
can easily distort the artwork.

 

Also it is critical to get sufficient opacity that a single layer artwork
can be used.

Bertho

 

 

From: Phil@Yahoo   Sent: Tuesday, May 21, 2013 15:31



Hmmm...

I'm a (relatively) new member here. I've been lurking. This is the first 
urination competition I've seen in this group but, human nature being what 
it is, I suppose they are inevitable. When I was in the first grade we used 
to see who could stand farthest back from the urinal. I could do more than 
six feet. Now that I'm almost 60 (yikes!) well, you don't want to know. A 
sad story.

Anyway, the topic: This is in fact the reason I joined. I make double sided 
PCBs with plated-thru holes, but have trouble going beyond 2 or 3 inches on 
a side because of the distortion caused by printing laser transparencies. I 
used negative file photoresist which works quite well, bit printing 
negatives exacerbates the distortion problem because of the large areas of 
black.

The contrast of the laser printer (I have a Brother MFC8500) is fairly poor 
so I have to stack up 3 prints to make it dark enough. Last time I tried 
inkjet (HP 932C) the ink wouldn't stick well enough to the plastic, so large

dark areas had lots of gaps (too much surface tension in the ink.) Recently 
I picked up a used Epson Workforce 630 for my wife [only $25 :-) but $70 for

ink :-( ] and decided to try printing a mask on that. I was thrilled! It 
looked perfect, with excellent contrast. But the test was a positive image, 
no flood fill.

Next board I made I printed on the Epson, but found the ink smearing and 
bleeding wherever there were large dark areas, and the fine traces (~12mil) 
tending to close up. Back to the laser. I know I could use flood fill to 
reduce the black areas on negatives, but that is not foolproof because the 
flood fill often cannot reach some spaces.

I recently picked up some Oracal to experiment with, but even with that I 
doubt TT will work for me because of inadequate contrast (too many pinholes 
in the black areas) though I am in the process of making a temperature 
controller for my Royal PL2112 laminator. I looked at replacing the 
thermostats but decided I'd rather have continuous control from hand-warmer 
to melt-down. Who knew a simple 1N4148 made such a swell temp. sensor? I 
have actually tried multiple applications of toner to a PCB. Too hard to 
align. But there are other interesting applications for TT.

Anyway, I would be very interested in learning which printers produce the 
best contrast with little or no distortion. I can't afford to keep buying 
inkjet and/or laser printers till I get it right, and I don't want to spend 
a fortune on equipment or consumables. If I could just throw money at the 
problem I wouldn't bother with DIY. I have a pretty good supply of NuKote 
laser transparencies and would prefer to continue using those. They seem to 
work pretty well with the Epson inkjet, though I'd grant there may be 
something that works better. If so, I'd like to know why. But again, I don't

want to accumulate a stack of useless transparencies searching for The One 
That Works.

OT; FWIW, I've found that conductive ink made from Silver Acetate is very 
effective as a hole wall activator. After drying and annealing at ~92C it 
forms a layer of metallic silver with a very strong mechanical bond to the 
hole walls, and as such is impervious to solvents. It is more expensive than

conventional DIY activators, and is quite toxic, but the shelf life is 
virtually indefinite, and I can make it in small batches. I thought about 
selling it in small vials but the toxicity argues against that. Some putz 
would probably sue me because his kid tried to snort it or something. 
Anyway, FWIW.
--
Phil M. 



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