Homebrew PCBs

On Tue, 30 Jul 2013 14:36:31 -0700, you wrote:

>Harvey,
>
>You make a lot of sense. The etchant will become "used up" sooner but should
>do the job. 

If you use the HCL/peroxide etchant, it's so cheap that you don't need
to worry too much.  It also regenerates with air, so you don't need to
worry about running out so much.

>
>I'm playing with etching text into copper. Having a bunch of little dots
>would not looks so good.
Actually, it's a crosshatch, and you get to pick the size.  It's not
the printing screen you'd expect in printing.

>
>Never heard of "green foil". A search turned up plenty of foil that is green
>but I doubt that is what you are suggesting.

Pulsar TRF film, Mouser has it, amongst others.


>
>One thing I'm playing with now is the use of 3M Blue painter's tape to hold
>on the artwork. It releases a lot easier than 3M frosty Scotch tape.
>However, the toner does not fuse into the metal after 10 passes through the
>laminator if this blue tape is over the top. 

It's acting like an insulator.  I use thin stationary labels used for
laser printers, say an inch and a half by about half an inch.  I
overlap the artwork on a border (no artwork at all) by about 1/4 inch.
I manage to do this only on one side, and always feed in from that
side.

For the laminator I use (GBC creative), I use the Pulsar paper (not
what you're using) and run through six times to 8 times, varying the
position on the laminator to avoid colder spots, and turning the board
over half way through (that may avoid colder top and bottom rollers).


>This time around I'm only using
>on the perimeter. David talked about wrapping the edges of the artwork
>around the board. That would avoid the problem of tape over the top of the
>artwork.

Good idea. however, if you have tape on all four sides, does the
artwork wrinkle?  May not be a good idea.

>
>Another thing I am trying right now is to take the sample out of the
>laminator after 5 passes and press it between two blocks of smooth aluminum
>with a big chunk of steel on top. I left it there for 1 minute and then put
>it in the freezer for 15 (not 30) minutes. The toner did not fuse at all. 

I'd think that the board does not get hot enough with 5 passes and
your laminator.  If you can set the temperature, try higher if it
already isn't at the top temperature.

Harvey

>I
>will now repeat the test with 10 passes, press, and freezer for 15 minutes.
>
>Rick
>
>-----Original Message-----
>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>On Behalf Of Harvey White
>Sent: Tuesday, July 30, 2013 10:16 AM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] Re: Easy Fast Laser Print DIY Circuit Boards -
>Dave's toner-transfer freezing technique
>
>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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>>
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>
>
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