Homebrew PCBs

Phil wrote:

> thanks.  here's the state of my "operations":
> 
> paper: I'm using magazine semi-glossy.  I'll try some of the coated 
> inkjet paper.  I did have a couple of sheets that I used a while ago 
> and think it had the same problem but I could be misremembering as I 
> was fussing with learning the process.  by the way, passing the paper 
> though the copier multiple times to increase the amount of fusing 
> seems to have no effect.  it does come out hot so I know its 
> getting "cooked".
> 
> toner density:  I've played with this a lot.  really cranked it down 
> and even at super light settings I am seeing the blotchiness along 
> with complete drop out due to too little toner.  In general, I keep 
> it on the light side.
> 
> heat:  I think I've got this right as i started high and kept 
> dropping it until the toner was not adhering, then kicked it up a 
> bit. I'm getting good aherence. Using the aluminum sheet metal seems 
> to improve the uniformity of the heating but there is still some 
> blotchiness.
> 
> pressure:  I still think this, along with uneven heating, is part of 
> my problem.  Its hard for me to control which is why I thought the 
> metal plates would do a more even/uniform job.
> 
> I'm not going to obsess over this blotchiness as it doesn't keep the 
> board from being usable, it just doesn't look super clean.  I'll keep 
> at it so Me Etch Pretty, Someday.
> 


http://www.jetprintphoto.com/c/graphicgloss.asp

   Try this, or find the Office Max Hammermill equivalent since this is also a 
Hammermill paper.  It has a good coating, and a paper sheet.  I think Office Max 
just bypassed JetPrint and bought their paper direct to make a bit more money.

   Note that magazine paper is very thin and dense, and most has a solid 
coating.  You will easily get the smashing of toner as you're getting, there is 
no where for the toner to go but out.  There are some who swear by the magazine 
paper mainly because it's free, but they also tend to swear you must use a 
laminator etc to get good results.  You can get great results from this paper 
without anything else being special.  And the extra fusing is to keep the 
coating from this type paper from sticking, I wouldn't expect it to do much for 
magazine paper.  I'd assumed you were already using good paper, you should try 
some just to understand the difference in quality and ease.  Even if you can 
live with the magazine quality for now you should see this so you know you can 
step up if you need to later.  You'll spend far more time trying to make the 
magazine paper process good than you will just buying the 50 cents a page paper. 
  And the 20 pages in the pack for $10 lasts a good while if you're judicious 
and print tests on normal paper first etc.

   Pressure is the problem, but you'll never be able to get it 'right' with such 
a solid dense paper.  You may find a mag with a thicker softer paper, but 
they're few and far between since transport bulk dictates that thin highly 
compressed paper is better for a mag.  For contrast I can barely make my prints 
smash at all or have uneven results, even with intentional wide variations in 
pressure.  This type paper is your limiting factor, not that you don't have 
superhuman or mechanical control over the pressure.

   A few sheets of normal paper behind may mitigate some of this.  But even then 
the coating on the inkjet papers is a bit different and seperates from the 
looser page better.  My prints leave the coating on the toner with only a little 
of the page sticking in the coating, and the extra coating tears right at the 
trace edges, and the resulting transfers are nearly perfect, even the holes are 
left clear even with almost all the coating sticking on the toner.  I don't 
think you could get that kind of coating seperation with the highly compressed 
tight bonding of the magazine coating and page.

   Actually I'll have to try some different magazines and see if there's 
anything out there that's as good.  Free paper would be good.  But from how most 
everyone using it says lamination is absolutely critical and knowing the basic 
construction of most pages I don't really expect to find it, but worth checking. 
  Using this paper and fusing an extra time or two so the unprinted coating is 
dried better and won't stick are almost my whole process, and hard to consider 
that a drawback since the paper and printer do all the work.  After that the 
ironing etc is all very simple, instead of having to get it exactly right it's 
almost impossible to go wrong.

http://photos.yahoo.com/alantak69

   Look in PCB, this was a rush job since I expected to have to clean it up and 
it was just a proto board anyway, so was going to have wire jumpers etc.  Even 
with hardly ironing so a couple small pieces didn't stick, it came out nearly 
perfect.  Note the second photo, smooth even fuzz almost everywhere, but almost 
no holes were covered so the copper was properly exposed for etch, and only a 
couple had to be picked at by hand.  Little secondary touch up or handling 
required.  Note the first pic, you can see the image in the coating on the page 
since the coating seperation was so clean.  I only spent about two minutes doing 
the ironing, a little bit more would have likely gotten a perfect transfer.  The 
route through the pins wasn't smashing, I had it drawn a bit wide in Eagle but 
it was still not touching and worked perfectly.  While the pics are a bit fuzzy 
from being close in, the trace edges were sharp.  If your results aren't equally 
easy and painless with just an iron by hand, maybe this will let you see it's 
likely your choice of paper.  It's hard for what I'm doing to even mess up.  The 
stepper board in the other album was a much earlier board, before I knew to fuse 
extra and clean the copper better with acetone.  Still came out well, but took a 
lot more hand work since the coating stuck much more.  That's what the extra 
fusing is for, almost totally eliminates any unprinted coating sticking with 
this easily seperated coating.


   Bit of a read but hopefully this will help you bypass the idea that you need 
to do a lot of work on heat and pressure, and get you to try some other ideas 
with a better paper.  It's much easier than fixing the process with the paper 
you're using right now, and well worth the 50 cents a page when printing boards 
to make everything else much less critical.

   It's even hard for me to really work on the print to copper idea too hard, 
this really is easy enough for my light to medium use, and doesn't take 
modifying a printer.  But I think our current ideas on that will coexist with 
normal printing now, so if the testing works it'll be worth finding and setting 
up one printer that can print fine on paper and also straight on copper board.

Alan