On 05/02/2010 22:25, awakephd wrote:
> I have only done three or four toner-transfer boards, with acceptable results. But recently I acquired a laminator, and I picked up an inexpensive hotplate, so I did some experimenting to test my techniques. Here are some results; if you read all the way to the end, I have a couple of questions. :)
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> Test results showing patterns for 10/10, 8/8, 6/6, and 5/5 (left to right):
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> http://home.earthlink.net/~a_wake/tt_test_closeup.jpg
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> The patterns have two inner blocks and traces of the designated size and spacing spiraling outward to two outer blocks. If the inner block and the matching outer block show continuity, then the trace is intact; if there is continuity between two inner or two outer blocks, then there is a short. All of these test patterns worked except the 8/8 -- there is a break in one of the traces, but not the other. No shorts anywhere. Surprisingly (to me, anyway!) the 5/5 pattern worked perfectly. I'm not sure I'd be ready to trust it for a real project, though! :)
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> Here is what I used to produce the patterns.
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> HP LaserJet P2015dn printer with HP toner
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> HP Presentation Paper, Laser Glossy, 34lb. I can't find the part number anywhere ...
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> GBC 2130 laminator. This has a built-in temperature control that will go up to 320 degrees -- which is where I set it to do this test. I ran it through on speed 2 (next to slowest) three times. Here is a picture of the laminator:
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> http://home.earthlink.net/~a_wake/laminator.jpg
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> ∗∗∗ very important: I peeled the paper off the board immediately after removing from the laminator! In the past, I have found that it is nearly impossible to get this paper off if you let it cool and soak it, but it seems to come right off, leaving the toner behind, if you peel it off immediately.
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> I etched in 2 parts drug-store variety hydrogen peroxide plus 1 part muriatic acid. Usually this is super fast, but today it took more than 10 minutes ... maybe because the chemicals were really cold, and I etched it outside in the cold.
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> After cleaning the board with acetone to remove the remaining toner, I put it on a small hotplate -- a 110v single burner with an 8" x 8" piece of 1/4" thick aluminum on top. I fluxed the board and then heated it up until I could tin it with some solder. I wiped the excess solder off while still hot.
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> Now for some questions: 1) The PC board turned a chocolate brown color after heating on the hot plate. If you look at the second picture above, you'll see the now-brown board at the bottom of the picture next to a light-green board that came from the same stock. IOW, the light green is the color it was before heating on the hot plate. Is this color change normal? Ominous?
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> 2) Does anyone else use the glossy laser paper as I've described above, peeling it off immediately after laminating?
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> 3) Any suggestions about any of the technique described above?
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> Many thanks to anyone who has actually read this lengthy post all the way to the end!
You must have overheated the board for it to turn brown.
Leon