Etching circuit boarda

Sorry about my misspelling in the titile

I havn't done it in a while, but from experience, for good results, a photo-sensitive method is required where the image is on a transparent sheet.

Other methods of transferring the pattern to the board directly have varying levels of results.

You'd need to experiment to get a totally opaque quality to your tracks on the transparent sheet. The best/correct way is to pay to get a photoplot

(i.e. laser plot) done, but that is not cheap. Many people experiment with printers and transparency sheets. It may take a lot of experimentation.

There are guidelines on how to etch (stuff to use, heat, agitation, etc) which you'll find with a web search.

If your board is through-hole, then you'll need to drill lots of holes afterwards, which is not fun. (And plating through-hole is not directly possible, if you

want double-sided boards).

You may therefore just decide to pay to get a board manufactured.

Anyway, most of the method described above appears to be documented here. I imagine quite a few people use this method or various

refinements of it.

How much do the copper plates and photosensitive spray generally cost per square foot of board?

Pre-sensitized board is convenient but costs more. Not sure about the cost of sprays.

I haven't done this sort of thing before, but I wish you luck!

I might try to squeeze a CNC PCB milling machine into Season 3

That would be cool Ben. I've won a prize but then would really  really want to win that one   Hope you can do that and make plans availiable.

I've tried toner method and hadnt had success with that. Tried with magazines, special paper and laminator, iron ugh.   Going to try photoresist method next and use the presensitized boards.  Seen trying to get spray evenly can be hard on some youtube videos.   I've tried using protoboards but a bit of a hassle for me.  Though might try the veraboard that have some traces that u just break as needed. They might be eaiser than trying to solder bridge everything and wiring point to point.

For buying regular copper clad board for the toner method, I bought off of ebay from this person http://www.ebay.com/itm/120664289524?var=420018556386&ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649.  Seemed to have good pricing and cut to size for free to fit what the free Eagle cad software can use.

For presensitized was thinking of ordering from here for their starting kit.  http://www.circuitspecialists.com/416k.html  Order some stuff from them before and was good quality. Seem to have best price for this kit with checking some of the other suppliers.

If you really want to go through the home-made PCB route (I stopped after a while, it was just too much hard work! ; -) and you're pursuing the non-CNC method, then step 1 is to confirm you can create a very opaque image on a transparency, by holding it up to a strong light. If you cannot, you should stop right there - otherwise it is just a wasted attempt at photoresist, chemical etching, etc.

The opaqueness is really key to a good result. If you can achieve that, then you can create very detailed boards fairly reliably.

For example, here is a photo showing two PCBs created with a professional photo-plot, but with home exposure and etching. They are both double-sided (with wires linking the holes), and you can see the lower PCB has some fairly fine tracks. It looks oxidized because it is quite old and was not protected. It still works (it was the last board I ever did with home etching). Some people print multiple times over the same transparency, to get it extremely dense. It really depends on the printer and type of plastic sheet. I've used a photocopier in the past (special plastic is required, otherwise it will melt).

The key point to Stage 2 is to ensure that you're using pre-sensitized boards. The spray-can method works, but it is hard to be consistent from one attempt to the next.

The key point to the chemical etching stage is to use a warm bath and some occasional agitation. Otherwise, it etches too slow and eats up the thin tracks. There are small heaters in a test-tube-like enclosure that are fairly low cost.

Hi,

Wanted to update on this. Received my kit and was able to make a couple of boards with it.  I might get/make an etchant tank to help with that part though. Otherwise process is pretty easy.  I follow Collin's process in this video http://www.youtube.com/watch?v=tWnfnt2rNO0.  What's nice about the presenitized boards is you dont have manually prepare them like in toner method, worth the bit more for me.

PS. I still hope "I might try to squeeze a CNC PCB milling machine into Season 3" can happen though. But if not season 4 please.

I'm in the process of designing a PCB that I plan to etch myself.  How do you get the copper ground plane to be separate from the pads and parts that aren't connected to it?  So far, in my board layout, only the wirepads seem to be separated from the ground plane.  Everything else seems to run right into it.  Is there some kind of script I need to run to format this thing for etching?

Thanks!

Hi Mike,

I'm not sure I understand, you may need to post an image of it.

Generally, with EAGLE, for a ground plane, all you need to do is route the board (manually or automatically) then

draw an outline using the 'Polygon' icon, and then  name it the same net name as your ground plane

(e.g. 'GND'), and then click the strange icon that looks like an 'X with blobs' (when you hover over it,

it says 'Calculate shortest airwaves'). This will lay a plane around all your existing traces, without touching any except GND.