Why not make in house multi layer PCBs? I hear that vias for DIY boards are usually just placed in and soldered on either end. Why not just do it how industry does it and plate them?
Prototype PCBs are a large cost of any electronics project. The ability to make reasonably high quality PCBs with low turn around time and cost would be useful especially when several iterations of a design must be made.
Not really. They used to be, but now you can get boards for a few dollars per square inch.
Also you really can’t diy 3+ layer boards.
But what about the process makes it difficult to DIY multilayer boards? What makes it difficult to etch on either size and laminate?
For 4-layer boards the prices I’ve seen for low volume is in the region of $8-10/in^2
+1 on this one. I have chemically etched 2 layer boards and lining up the vias is a pain in itself, its a very labor intensive process, and they have to be lined up perfectly.
Once you get into 3+ layer boards, you have to go professional, and from my experience you are guaranteed a few bad batches before they even get it right. The issues are getting all the traces to test out and working the way you want. I’ve seen a few folks just give up on a project due to test costs of wasted batches. They couldn’t get the board to work due to the inconsistency of the vias and trace connections.
Not sure if your familiar with the 2 layer process, but you have to fab your top routes, realign and mirror your bottom routes, so the connections are aligned. I use the old classroom light projectors to align my routes.
Then drill through and use thin guage solid wire or kynar wire fed through each via and soldered.
This is one of the boards, i did, so take this example and think about pancaking 2 other layers on top of this. You will run into via issues as there is no solid cheap way to fill your drill holes with conductive material to connect both sides. Go online and check the prices on the those pop in via’s and the tools to do it, its very expensive.
Also plating/silkscreening its not easy either.
Honestly by the time you ruin a few batches, your better off just going to a professional to do it, i’ve had lots of success with 2 layer boards from ITEADSTUDIO and they are pretty cheap. So the 4 layers might be in your price range, you might even look into the sheets, where you just have to cut out each board yourself. To keep costs down just go with the standard green and the standard copper thickness, you start adding color and odd copper thicknesses your price goes up.
So good luck in your journey, if you figure it out, that’s one helluva class to teach, i’ll certainly show.
Two layer boards aren’t that difficult, particularly with cnc and/or fixturing.
But for more layers, how do you assemble your multiple boards (typically can only buy 2 layer for etching)?
The thinnest double sided boards I can typically find are 1/32". So you can sandwich two to get four layer, but then you have to have a blank board in between to eletrically isolate your second and third layers. At that point your dealing with a 3/32" board which is pretty thick. (Yes there are some other techniques, but they increase time and complexity.
$10 per square inch for a four sided board with solder mask (really helpful with SMD parts) and silk screen is incredibly cheap. Wasn’t that long ago it was ten times that value. The turn around is also pretty good as well.
The holy grail of 3D printing would be to print prototype PCBs. Now if only we had $9K we could get one of those …
Chris
PCB also has higher melt temperature - soldering onto PVC or ABS would melt way before the solder even started to get soft.
Advanced Circuits uses Isola FR402 and FR408 laminates. These are available in a wide variety of thicknesses and (if desired) copper cladding. DuPont makes photoresist and soldermask chemicals. A photoresist would be required for etching and plating the vias. With a fixture, I don’t believe that it would be difficult to repeatedly position the mask and board either.
there’s also these slides available from Advanced Circuits
Chris,
If you want to try it, then by all means do so. However, I doubt you could DIY for less then you could purchase, at least for the first few trys. Also, if I remember you telling me this correctly, this is your first foray into designing your own boards. A four layer is not a real good choice for your first try, if that is the case.
Think of it this way. Do you think someone should try five axis machining, if they have no experience with three axis? Can they do it? Yes. Is it the best approach? Probably not.
Also, don’t assume you need four layers. Your board MAY need more then two, but you can accomplish some amazingly complicated boards with only two layers and a few jumpers.
I’ll second this, though in my case it’s two layers and a LOT of vias. I think I make more work for myself avoiding jumpers, but I like the look better.
Also, I wonder if one could use Nylon as a printing material for circuits. It’s a little higher temp…one would definitely have to have a light touch with the soldering iron, lighter than I do probably.
If, in your research, you come across a good supplier of boards thinner then 1/32", please let me know. I could use some thinner boards, but can’t find a good supplier.
I use this guy on EBAY for my PCB copper needs he has huge selection, i’ve done a few boards in the black looks cool. ABCFAB, his name is Bill
I suck at fractions to decimal, but i think this is thinner than 1/32.
It is. 1/32" = 0.0325", so your source is 10 thousandths of an inch thinner. Just hate buying stuff off of ebay…
Thanks for the link, though!
This guy is reliable, answers emails, and messages. Knows his stuff, and will customize an order for you. I have used him for years, and have had no complaints and or hiccups.
Oh, I already ordered the 6 pcs of 8x10 board, just hate ordering stuff from ebay. Makes me feel sleezy. Not really sure why. But it feels like a black market to me…
I always think of it as a cheap way to get your product out there. I mean you can go mainstream and pay alot more for the same thing a direct vendor can get you at a cheaper price.
Way i see it, everything we buy is black market, some people just make it look more appealing than others…
Glad i could help you out though…and hopefully you have a good PCB source now…you sleezy man you 
Oh, don’t get me wrong. I don’t think my feeling on the subject has any validity, it is just how I feel about ebay. Doesn’t keep me from buying on that black market occasionally if it is the only place I can get something. Just need to take a shower afterwards. 
Pssst, hey you. Yeah you! Wanna buy a circuit board? I got the good stuff, thinner than the MAN wants you to have!
Actually, my addiction involving ebay is old metrology tools…
