Home etch double sided boards?

[RobA]

OK, so this is probably a really stupid idea, but...

I'm getting antsy waiting for the first PCB I did to come back from OSH park and I want to do a couple of more prototypes. I don't want to spend a lot of time laying out stuff that won't work, so I was planing on waiting until I had the first board back before I did the next one so I could make sure I was doing things the right way and my library was working. But, I've got to get started on the next stage. So, I came up with this cracked idea to make a double sided layout, burn them on two boards and then glue them together. I figure I might be able to get them aligned if I drill a couple of the holes very carefully and use this as a way to keep them aligned while gluing and then drill the rest of the holes after it's together.

Anyone ever try this? Or, is it just too silly?

[kothoma]

Getting it aligned is not the only problem.
The legs of many sockets may be too short for double whoppers.
Also some caps come with very short legs.

[Vallhagen]

... burn them on two boards ...

Why on two boards, when there are doublesided boards out there? It must be simpler to etch a doublesided board directly (though i have never tried).

I understand that you dont feel like doing an additional PCB layout for single etching. But how about this simple workaround: As I guess most of your traces are on one side (bottom) of the PCB, you can do "ugly jumpers" for the (fewer) top traces. it wont "look good" but will do the job and after all its prototyping.

[RobA]

Getting it aligned is not the only problem.
The legs of many sockets may be too short for double whoppers.
Also some caps come with very short legs.

I just happen to have some thinner than normal board -- not quite half as thin, but close. But, you are right, it could be a problem with some parts.

[RobA]

... burn them on two boards ...

Why on two boards, when there are doublesided boards out there? It must be simpler to etch a doublesided board directly (though i have never tried).

Two reasons. The first is that I don't have any double sided board. I guess I could solve this issue. The second is that I have a hard enough time just getting transfer placed on the board so it would work. I don't think I have the spatial skills to pull this off. It would be worth trying though, if I end up doing this very much.

I understand that you dont feel like doing an additional PCB layout for single etching. But how about this simple workaround: As I guess most of your traces are on one side (bottom) of the PCB, you can do "ugly jumpers" for the (fewer) top traces. it wont "look good" but will do the job and after all its prototyping.

It's not so much that I don't want to a second layout. I actually started by trying a single sided layout and couldn't get it to work in a small enough space to be useful. The other thing is that this is a digital board and kinda needs a good ground plane...

But, you did prompt me to bring up the the layout again and realize why this is a bad idea. Metal bodied parts, like the crystal, are going to be a pain. The body crosses multiple traces and would short them. I'd also have to do a different version anyway with a larger standoff from the ground plane and the pads and it might not be a good test after that.

I think this idea goes on the junk heap.

[stevie1556]

I tried doing a double sided board. Near impossible to line up, d it was a complete and epic failure. 3 times I tried. Never again.

If you do go ahead with it, I wish you luck!

Sent from my thumbs using Tapatalk!

[RobA]

I tried doing a double sided board. Near impossible to line up, d it was a complete and epic failure. 3 times I tried. Never again.
...

That's pretty much what I figured would happen if I tried to line up things on a two sided board. I guess I'll just have to live with the time lag of getting them commercially produced.

[hammerheadmusicman]

I did a couple, but they were a horrendous nightmare, lining them up etc.. think it took a few attempts, but it worked.

Just get some boards made, it's so much easier and better!

George

[midwayfair]

Could you add two dummy pad in pre-defined spots on both sides of the layouts, drill a hole with one transfer as a guide, and line the other side of the etch up against those two holes?

[davent]

I believe people create an aligned "sandwich" of the two pieces of art, tape one side of the snadwich together to form a hinge then slip the double sided board into the sandwich, secure the art to the board so if won't shift around, do the transfer. I would think some sort of laminator would be ideal for doing the transfer.

dave

[RobA]

Could you add two dummy pad in pre-defined spots on both sides of the layouts, drill a hole with one transfer as a guide, and line the other side of the etch up against those two holes?

Yeah, this is pretty much what I was thinking of doing to try to align them. There are pads that'll be on both sides that are far enough apart on opposite corners of the board that I think I could just use them instead of making alignment guide holes though.

[RobA]

I believe people create an aligned "sandwich" of the two pieces of art, tape one side of the snadwich together to form a hinge then slip the double sided board into the sandwich, secure the art to the board so if won't shift around, do the transfer. I would think some sort of laminator would be ideal for doing the transfer.

dave

Interesting. I have to think about this idea. I don't have any sort of laminator. I'll look at what's available and the cost. I just use the iron on method now. It'd be a bit problematic doing a double sided though since the first touch of the iron tends to move the transfer a tiny bit as it sticks to the board. It would probably bit bit tough to keep the unfused side safe while doing the first side with the iron on method too.

After that, I'd still need to figure out an insulator to keep the front side metal parts from shorting the traces they cross and potentially having to solder the frontside pads under parts (yikes!).

[culturejam]

But how about this simple workaround: As I guess most of your traces are on one side (bottom) of the PCB, you can do "ugly jumpers" for the (fewer) top traces. it wont "look good" but will do the job and after all its prototyping.

This is the best idea I've seen so far. Route mostly on the bottom and then manually wire up the top.

[Haberdasher]

I did it the other day on dbl sided copper clad.  the pcb came out great but my circuit didn't work in the end.  i blew a day & a half on that and ended up frustrated.  i have little hope of finding where the error is because some things are soldered in on the component side and obviously it is difficult to get any sort of a line of sight under the components, even though I left them partially raised.  it is possible that wiring things up on the top could work better.  that was the first idea I had but I decided to solder right on the pcb instead since there weren't too many connections there anyway.  but i can tell you, even a few are a lot in terms of general PITA'ness.  Plated through holes rule for double layer pcb's.  If you could just figure out how to use those it'd be golden.

I would recommend making a version of your circuit that doesn't have a 9v pour on the component side.  either that or increase the tolerance a lot as well as the size of your route traces, because the margin for error is just too great otherwise.  of course if it is a complicated design I realize that could cause all manner of clearance problems....

[davent]

Just what kind of circuits are people doing that they even need a double sided board? I've dozens and dozens of pcb layouts for everything from simple pedals to discrete component stereo amps and it's rare to even need a single jumper on the top side of the board.

dave