Working with wooden breadboard - recommended materials

Question

For certain reasons I am interested in constructing low power circuits using wood instead of PCB/Protoboard as a surface upon which to place and join components. Although many might find this silly, I still want these circuits to be high quality, rugged, efficient, and just as functional as a circuit not laid on top of wood.

A simple method to achieve this in my mind would be to place screws as junction points, then solder the component wires to these. The solder connection should be sufficient to hold light components. Heavier components I plan to investigate fixing to the board with fasteners.

My question is this: Will any commonly available screws (zinc, stainless steel, ...) have sufficient conductivity to produce an efficient circuit. If so would a certain common material/conductor be preferable? I assume size will effect the resistance/conductivity? Should I measure the resistance of the screws to get a good experimental idea of their resistance/conductivity? Is there a certain range that I should be looking for?

If commonly available screws are not sufficient, my next idea was to look into hammering solder header pins to the wood, however I am worried they could come loose from the wood over time.

Answer 1

Wood does not really like soldering temperatures, so you may want to minimize the conduction to the wood. You could consider ordinary sewing pins, which are generally made from steel but with a plating that is solderable, at least some are. The steel will have poor thermal conductivity and the pins are reasonably small (0.65mm in the sample I liberated from my wife's storage). This is similar to the construction of many component leads (plated steel) however the leads are made from soft steel and the pins are stiff so they can be driven into a soft wood like pine easily.

This is actually pretty robust mechanically. For heavy things or things that go off the board you could use standoffs (you can even get 4-40 threaded wood inserts to do things really nicely- they have a wood screw thread on the outside and an internal thread that accepts a machine screw threaded standoff etc.)

You can also get solid brass escutcheon pins (dome-headed nails- the sort of thing you'd use to fasten the hinges on a jewelry box) but they are much larger diameter so they'll carry and hold a lot of heat. Also, more expensive.

As far as electrical characteristics go, there is a fair bit of (generally old) information on wood. Dielectric constant of dry wood can be lower than epoxy-glass, conductivity is highly variable. For ordinary (up to 1M\$\Omega\$ resistors and not high precision where there are high impedances) probably you won't have to worry much for dry wood kept indoors and especially if you varnish it.

Answer 2

These might meet your requirements. Screw it down to the wood, bend the tab up.

Or, there are phenolic strips with multiple solder lugs and an L bracket to screw them down (normally to a metal chassis). Some early TVs were wired this way, point-to-point, no PWBs!

Both from Amazon.

Answer 3

When I was really young, just getting into electronics, my Mother gave me a wooden board, some screws, and a bunch of these:

I got that picture from this supplier: allfasteners.com

They are called "countersunk washers", and can be used with regular countersunk wood screws to pinch down onto multiple wires or component leads, connecting them together.

Perhaps that's an option for you.

Answer 4

Steel will not accept common electronic solder. So you'd need screws made from solderable material, like copper or brass. I mean, not steel with a coating that makes it look like it's copper.

Brass will probably be cheaper and look more steampunk. It solders easily with an electronics soldering iron, but if there's a large chunk of it, it'll take more power to heat it.

However, once the screw head is full of solder, it'll be impossible to remove. So you could use brass nails or tacks instead. These should not be varnished.

If the goal is aesthetics, you should protect the wood while soldering, otherwise it'll be full of flux stains. You could use a mylar sheet ("laser projection sheet") with the schematic printed on it, then rip it off, or maybe just paper. Or varnish the wood first. This would need some experimentation.

Current leakage through the wood should be higher than FR4 and depend on ambient humidity.

You could also make a PCB and glue thin wood veneer on it, then re-drill the holes...

Answer 5

Why screws? @SpehroPefhany has already suggested sewing pins, but (at least in the UK) there's an even easier alternative---copper panel pins, which solder very nicely, have a low enough thermal mass to solder with an 18 W antek iron, and are readily available at every DIY/hardware shop/screwfix/amazon.

If you print the circuit diagram and glue it to the board below, and then drive pins at the junctions, you can solder the components directly between, following the layout of the diagram. I've seen this used for teaching in amateur radio clubs, and has the advantage that not only can one follow the schematic very easily, one can hook a probe at any point (either to lead or to nail).