20091107

Circuit Etching Test

Using some variant of the instructions found here, I was able to etch a small 1"x1" test board.


Current problems : surprisingly few. [1] OpenOffice, which I used to draw the design, does not scale correctly when printing. Much searching on the internet did not resolve this problem, and ultimately I guessed as to the correct scale at which to draw the design. Suggestions for a better free drawing program would be welcome. [2] There was a 1mm misalignment between the two board sides. This makes through hole mounting.. tricky to impossible ? I will have to try harder next time. [3] I do not have a drill press, and Home Depot does not sell bits small enough to drill out PCB holes. I will simply use only surface mount designs in the future, to avoid this problem. [4] I do not know how to reliably get good close-up shots with my cheap digital camera.

Significant deviations/simplifications/shortcuts from the internet instructions : [1] I did not prepare the board with acetone beforehand, I scrubbed it a bit with steel wool. [2] I did not have to soak the board particularly long to remove the paper. I simply left the board in warm water for a few seconds then slowly peeled off the transfer paper in one piece. This created a nearly perfect mask. [3] I did not have to heat or agitate the etching solution, I just ignored it for twenty minutes. [4] I removed the mask with a q-tip and acetone, no abrasion.

Update : I tried some surface mount style soldering practice on the board

Since drilling holes is a major nuisance, I decided to try soldering an IC directly on the surface. I cut about 1/2 the leads off and bent them inward. I then tinned both the pads on the board and the leads. Connecting the chip was then as simple as briefly touching the joint to melt the two pools of solder together. The chip ( a hex inverter ) still works despite using no anti-static precautions, no heat sink while soldering, and hooking it up to twice the operating voltage backwards. Surface mount soldering of 0.1" pitch components turns out to be fairly easy, so I see no reason not to use surface mount design in the future. Soldering of smaller surface mount components appears to take a bit of cleverness.


2 comments:

  1. Hello there, I stumbled onto your site randomly while bouncing around the net. Cool blog! Just wanted to mention that Harbor Freight sells a few sets of very inexpensive, teeny tiny drill bits that are perfect for stuff like this. Here's one.. www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=44924.

    -~D~-

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  2. hey cool,

    <rant>

    you know... I've been thinking about advertisements, and how they make me angry. However, the reason advertisements make me angry is that they try to get my to want things that are useless. In my opinion this damages the economy, scientific progress, and public health.

    Now, if only someone would have run an advertisement for these little drill bits... I would have been able to have holes in my circuit board, the drill bit company would have made money sooner, and we wouldn't have to deal with shitty deceptive advertising.

    Maybe Google ads is heading in this direction, I sure hope so.

    </rant>

    ReplyDelete