Homebrew PCBs

Robert,

My second try was MUCH better.  I noticed that the pitting was 
actually more like streaks, all going in the same direction. Perhaps 
caused by the gel?? Or not enough fusing?? Anyway, this time I used 
no gel, then ran it through the laminator 4 times, once in each 
direction. I etched it, and the results seem about perfect. No 
pitting, no smearing. The 2 mil traces are perfect! I suspect I can 
get them closer together than the 10 mil centers I am using now, but 
these are pretty fine traces and more than adequate for what I usually do.

I used a precision optical sensor to find the leading edge of the 
board as it enters the printer. I wonder if I can make double sided 
boards with adequate registration? For now I think I'll stick with 
what I have. A double sided board can easily be made using thinner 
board and gluing two boards together using registration holes and pins.

Mark



At 06:59 PM 4/2/2008, you wrote:
>Hello Mark,
>                   An afterthought or two.
>
>I find that when I have to visually examine something in fine detail, it is
>easier to scan it on my scanner at maximum resolution and then scroll
>through the image on the PC screen. Perhaps you can do this with the fuser
>PCB to look for clues.
>
>If the problem is air pockets then it may pay to go over the PCB with very
>fine sand/emery paper (1200) before printing.
>
>Robert.
>
>----- Original Message -----
>From: "Mark Lerman" <mlerman@...>
>To: <Homebrew_PCBs@yahoogroups.com>
>Sent: Thursday, April 03, 2008 7:16 AM
>Subject: [Homebrew_PCBs] Direct Toner - First Try Results
>
>
>I just made my first (single sided) board using my modified laser
>printer that deposits toner directly on the board. A few observations
>and questions:
>
>1- I used the Eagle Demo2 board, but inserted four 2 mil traces
>between 2 of the dip pads, each connecting to one of 4 adjacent pads.
>These are 2 mil traces on 10 mil centers, with the traces on the
>sides being 7.5 mils from the pads.
>
>2 - I used some of Dave's gel on the 1/32 inch thick board - will try
>without it later.
>
>3 - I then ran the board through a laminator once - no carrier.
>
>4- I etched using muriatic acid / peroxide, room temperature, a
>little agitation by hand rocking the board.
>
>The board came out okay, but there is some pitting that I am not
>happy with. All four 2 mil traces are intact, none of them are
>shorted. Questions:
>
>1 - Should I have run the board through the laminator more than
>once?  I bought the laminator at Staples, no model number on the box,
>but I believe it is one of those recommended on the laminator link.
>I'll have to measure the temperature sometime. Any other thoughts re
>the laminator?
>
>2 - Would I be better off using an oven or hotplate to fuse the
>toner? I can control the temperature quite well, but will the toner
>fuse well without the pressure?
>
>3 - What causes the pitting? Too long in the etchant?   Toner not
>completely fused? All the traces and pads seem equally pitted, so I
>don't think it's the trace width.
>
>Lots of questions, but I realize that I am on somewhat uncharted
>territory here. It's going to take time and experimentation to work
>it all out, but I'm excited by the possibilities of this technique.
>
>Mark
>
>
>------------------------------------
>
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>
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>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>