On Tue, 30 Jul 2013 09:30:35 -0700, you wrote:
>I'm not "there" yet but am getting close. The silicone based parchment paper does give up most but not all of its toner after 10 cycles through the laminator and 30 minutes in the freezer. I think my main problem right now is toner density. The artwork is not a solid black. So any thin spots in the artwork appears as thin spots on the copper. However, where there is toner, it solidly fuses to the copper which is great.
>
>So now I am waiting for the laminator to heat back up so I can run a better print through it. If this does not work, I will go to a positive artwork format so only black letters are present on a white background. Less toner so probably it will be darker. That will mean more copper to etch which means longer etch time. The longer the time, the higher the probability that the toner will breakdown.
I think that the "more copper" argument has little effect on the total
etching time. If you have enough etchant flow, I'd simply expect the
same "density" of etchant on each square area of the board, and if it
etches, it won't be at a different rate. In etching different sized
boards, I haven't seen all that much difference in etch times. It's
more related to etchant strength and temperature than otherwise.
The problem with most xerox process copiers is that charge tends to
congregate at the edges of the black area. They've come a long way in
fixing that problem, but it still exists. A large black area of toner
will almost inevitably be thinner at the center.
One way to "fix" the problem is to use a crosshatch fill with very
small dots that still shields (mostly) what you want to shield, but
the laser printer sees as a series of small lines with a lot of edges.
That is also a trick to control board warpage, since (at least they
used to) warp with large areas of copper. That may be a definite case
with older paper based single sided boards.
You may also want to consider green foil or the like to "seal" the top
of the toner, which may help a lot in making the board a bit more
rugged as well as eliminating some of the holes.
Harvey
>
>Bottom line: David's process is showing a lot of promise even though I am taking liberties with the paper.
>
>Rick
>
>-----Original Message-----
>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] On Behalf Of Rick Sparber
>Sent: Tuesday, July 30, 2013 7:58 AM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: RE: [Homebrew_PCBs] Re: Easy Fast Laser Print DIY Circuit Boards - Dave's toner-transfer freezing technique
>
>The test has begun. I printed out some artwork using Microsoft Word and my HP laser printer. I'm using silicone based parchment paper. The artwork is mostly black with white letters so the letters should etch out. I used the "WordArt" feature inside Word to mirror image the text.
>
>I cut out one of the four test coupons and taped it at the ends on a piece of thin copper plate. I'm using 3M Matte Finish Magic Tape.
>
>I then ran it through my laminator 10 times. It is now in the freezer with 21 minutes to go.
>
>One mistake I think I made was to not tape it all the way around. Before placing in the freezer, I saw places on the side where the artwork lifted up. If this is a show stopper, I will clean off the copper and use another coupon.
>
>Using the laminator is pure genus!
>
>Rick
>
>-----Original Message-----
>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] On Behalf Of David Pickering
>Sent: Tuesday, July 30, 2013 1:07 AM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] Re: Easy Fast Laser Print DIY Circuit Boards - Dave's toner-transfer freezing technique
>
>That's the one Robin
>As I said it does come in rolls and its quite thin so you will need to flatten it out, if in no rush just put it between some books for a couple of days, if urgent just run it through the laminator a couple of times
>
>
>________________________________
> From: Robin Whittle <rw@...>
>To: Homebrew_PCBs@yahoogroups.com
>Sent: Tuesday, 30 July 2013, 8:05
>Subject: Re: [Homebrew_PCBs] Re: Easy Fast Laser Print DIY Circuit Boards - Dave's toner-transfer freezing technique
>
>
>
>
>Hi Dave,
>
>Thanks - I ordered this material:
>
>http://www.ebay.com/itm/170900415631
>
>A4 10Pcs Sheets Heat Toner Transfer Paper For DIY
>PCB Electronic Prototype
>
>1,677 sold. It cost AUD$2.21 including shipping from Hong Kong from
>seller http://myworld.ebay.com/shcfstore.
>
>- Robin
>
>On 2013-07-30 4:39 PM, David Pickering wrote:
>
>> The paper and supplier that I have been using is on the page you
>> sent marked dib-bid and the suppliers name is shcfstore.
>
>
>
>
>[Non-text portions of this message have been removed]
>
>
>
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