Single sided vs. double sided pcb boards

Hi!

Why all the pcb designs are double-sided?
Producing double sided pcbs at home is way more difficult than
single sided.

There are simple circuits where double sided design is just luxury:
[www.reprap.org]

I think (in the future) a good solution would be to design the simple boards as single sided and only the more complicated ones should be designed double sided.
(where the double sided design have real impacts on the board area and price)

If people starts doing pcbs at home, they will also think about helping the process with a reprap machine. And I think the whole point of reprap is about reproducing himself and it includes the pcbs too.

What the others think?

I'll agree with the double sided boards being a pain to make at home.
I'm in the process of converting some of the double sided stuff to be single sided boards as I get time.

I know the feeling with double sided boards.

One trick that I've found useful when designing boards is to lay out the majority of tracks on the bottom layer, then place the tracks that wouldn't fit on the top with suitably located vias so that the board can be etched single sided and completed with wire links.

While it possible to fit a lot of tracks onto the bottom of a board, it is important to consider the implications of long wiggly tracks:
1) Earthing problems - high (or medium) currents flowing through windy earth traces can cause your 'ground' rail to have significant voltage differences between the two ends. Especially if the track goes all around the board as part of a circuit.

A good idea is to attempt to separate (as much as possible) the analog, digital and power earths, bringing them all together at only one point.

If possible, ground planes are good - they provide a nice low impedance earth for all your stuff. Once again, try to separate the analog, digital and power parts of the circuit so they each have a separate ground plane.

2) Noise / coupling - this shouldn't be a big problem with the Reprap stuff I've seen so far, but it will be an issue when people move to switched mode driver circuits for motors / heaters etc. (I personally feel that switched mode motor drivers are worth the extra fuss - they can be very efficient (smaller, cheaper power supplies), and have excellent dynamic performance (allowing for high speed rotation of stepper motors) ).

Jono

> One trick that I've found useful when designing boards is to lay out the majority
> of tracks on the bottom layer, then place the tracks that wouldn't fit on the top
> with suitably located vias so that the board can be etched single sided and
> completed with wire links.

This is an excellent idea!

Maybe we could start a wiki page about design tips to making single sided boards.

I add my tricks here:

* The smallest pad size: 0.08" (for though-hole)
* If 0.08" is too small, the next step is: 0,2" x 0,1"

I drill everything with 1mm (pad size: 0.08") and 2mm drill tips (pad size: 0.2" x 0.1")

The 1mm and 2mm drill tips are really cheap compared to the special 0.8mm and 0.6mm tips. (10cent vs. 3 dollar)

* For smd pad size there is no problem, I leave it as default.


For tracks, the general rule of thumbs is, make as large as possible.

Best regards,
Khiraly

Hey Guys,

I understand where you're coming from, however pretty much all of the boards are autorouted. I'll attempt the autorouting with single sided first, but it doesn't always work. Making single sided boards isn't 'my itch to scratch' so to speak, so I dont worry about it.

If you want a single sided board, the files are all up on sourceforge or subversion for you to work with. If you come up with single sided boards for any of the circuits we have developed, please let me know! I'll put them back into subversion and/or sourceforge for you!

Sorry to put my nose in again, but I think double sided boards are really not that difficult to produce. For the ink-pen approach, just mark and drill all holes first then use them to connect the lines on both sides, using a printout to help your way.

If you go the photo etching way, you just need to tape the transparencies together making the holes match. Then just expose one side at a time in your whatever UV-light box. Generally your misalgnment wont kill you at the 1/10" spacing used in this construction!

The thing that is the real pain in my oppinion is the vias.

The problem seems to be that some components can not be soldered on both sides, such as IC-sockets, connectors and alike. Also the L298 is a pain to solder both sides :-(

Transistors diodes and resistors on the other hand are easy to solder on both sides.

I have made altered PCB's from the originals for the UCB and the serial board.

What I basically did was just move the vias out from the difficult components.
Also I moved a connector so that I could squeeze the UCB on a standard 3 by 4 inch PCB.

I'll post the kicad's here if there is an interest!!!

I have made & tested the boards at least to the point where the PIC is talking to the Java software.

It took me some time to solder in all the vias, using some old copper wire from an electrical appliance. But it is no harder than soldering resistors!

With the developments of tofletcher (milling PCBs), I'd love to see single sided board designs. This way I could make RepRap boards myself along with the sets of RP parts I intend to make for friends...

I just switched to Arduino, so my PIC based electronics will be reused in other projects (a good H-Bridge is always useful).

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Regards,

Erik de Bruijn
[Ultimaker.com] - [blog.erikdebruijn.nl]