Which plastic? "PCB" basis

Sometimes I want to mount a few components on a largish (20cm x 20cm) "board" of some kind.

I would interconnect the old-fashioned way... discrete wires soldered between component pins.

Can you advise what sort of plastic (or other material!) would be good? I'd like it to be fairly rigid... a bit like thin PCB would be perfect. (PCB material too expensive for my taste, in large sheets.) (It doesn't have to be particularly robust... it wouldn't be subjected to significant stresses.)

Easily cut would be nice... the sort of plastic that DVDs are made from would be good... apart from it being quite hard to cut nicely. (I only want flat boards. I don't need something that can be molded, transformed to non-flat-plane shapes.) (Maybe you can advise on a good way to cut the DVD plastic?

I realize that if I drill small holes for through board leads, and try to solder to leads passing through them that almost any plastic will generate obnoxious (or just plain noxious!) fumes. (I have "an answer" for that problem)

I'd guess thin plywood will be the cheapest thing you'll find.

For plastic, you might check out what's on the shelves at the local pound store. I bought a bunch of binders at the dollar store a while back simply to harvest the vinyl covers for sandcarving stencil material. It was much cheaper than I could purchase the same raw sheet stock for. That particular item might not be as rigid as you need for your application but it's an example of thinking outside the box.

Perfboard is pretty cheap, too. Especially the crappy kind that doesn't have the holes plated through.

Start to look at different packaging used in store items and shipping materials.

Have you ever “potted” a circuit?

A good source of free sheet plastic I found is the cube shaped ~5 gallon oil jugs restaurants use to fill their deep fryers. Usually you can find piles of these jugs behind the restaurant or maybe ask them if they can set them aside for you. This is HDPE, which doesn't put out toxic fumes when burned like vinyl does. It's a little thicker than the binder covers I bought but maybe a bit less flat. Still maybe not as rigid as what you might be looking for. Maybe you could try gluing a couple layers of either one together? The oil residue is really a pain to clean off completely (scary to think of that stuff clogging up my arteries!) but a few runs through the dishwasher will do it.

Many thanks, Pert, for both your comments. I agree that the occasional "score" in those places where we who hate waste can get great bargains in our "throw away" society are wonderful... but being very ignorant in the world of plastics, I'm willing (for this!) to spend a LITTLE more (hurrah Amazon, eBay... sorry, retail world...) to use something I can go back to again and again, once I find the "right" material for my wants. The hdpe big "can" material an excellent idea for my wants. (I can live with slight non-flatness... rigid is the main thing, and that would be rigid enough.)

Further to my wants: plywood seems expensive in the very thin grades, or too thick. Stiff card is suitable for some of my wants... and has been used!... but for other wants, the vulerablity to moisture is a deal killer.

wvmarle: Thank you for reminding me of perfboard! Last time I looked, it was "expensive"... but much better luck, this time. (eBay). Still interested in learning more about material science of plastics, though, if anyone has thoughts... ease of cutting, thermoplastic (or not), what solvents work for solvent welding. Etc.

GoForSmoke... MORE good ideas... thanks. I do use the "make shelf-friendly" heavy plastic... on which people actually DO slit their hands open, trying to get at what they bought (asked an ER doctor friend). Need bigger bits, sometimes, though, and a LITTLE thicker helpful.

Sorry my replies haven't kept up with helpful comments... I started a reply hours ago, but nw comments keep coming in as I type, and I forget to promote "preview" to "post"!

Both the plastics I mentioned can easily be cut with scissors. They don't have the annoying tendency to crack like some other types of plastic.

I use a soldering iron with a "stencil burner" tip (which is a long thin pinpoint tip) on it for cutting designs out of the plastic. It doesn't actually burn the plastic, only melts it. I have a really good fume hood for my glass work I do this under but even with that the vinyl is probably not a good idea. I actually don't use that stuff anymore since I discovered the more durable, free, and less toxic HDPE source. I have a piece of window glass that I tape the plastic sheet to. Under the glass is the design I want to cut drawn on a piece of paper. Although not clear, the plastic is transparent enough that I can see the design on the paper through it. The glass sheet protects the paper from the burner and gives a nice smooth surface for the tip to slide over. It leaves a bit of a burr of melted plastic along the top edge of the cut so after finishing with the stencil burner I go over all the edges with a flat tipped hobby knife to shave that burr off.

I need the plastic to be flat while cutting but then I am typically using it on top of roughly cylindrical shaped pieces of glass. I found that I can wrap the plastic around a glass tube a little smaller diameter than the target piece (because the plastic springs back a bit after forming), then put in boiling water for a few minutes to permanently thermoform it into a curled shape. I found the vinyl can uncurl over time but the HDPE holds the form permanently (unless I thermoform it again).

Try looking around in a home/builder supply store.

If you don't want big, paint samples come on thin wood squares.

DIPMicro has a special on copper clad 8 x 2 5/8" boards, 84 cents each. http://www.dipmicro.com/store/PCB-D60F-8-2

They're good for dead bug style wiring. There's one youtube where a guy took a copper clad board and cut strips off one end and made rails and squares that he epoxied to the board, making a ground plane with solder points on top. It had no holes but the parts weren't going anywhere.

Watch that what you do use that it won't make static. 20V can eat a FET.

I often use cheap copper clad FR4 material. Wear dust mask when cutting. Some times I etch off all the copper, sometimes I use the copper i.e. solder objects brackets etc. to the surface.

For plastic, my favorite is acrylic as it is effectively welded with Fastbond/DCM/Metholyene Chloride (may cause cancer in California). Always drill with a step drill, can be threaded, comes in all colors incl clear.

ABS is okay and styrene is crap.

larryd: I often use cheap copper clad FR4 material. Wear dust mask when cutting. Some times I etch off all the copper, sometimes I use the copper i.e. solder objects brackets etc. to the surface.

For plastic, my favourite is acrylic as it is effectively welded with Fastbond/DCM/Metholyene Chloride (may casuse cancer in California). Always drill with a step drill, can be threaded, comes in all colors incl clear.

ABS is okay and styrene is crap.

Does dichloromethane not cause cancer outside of California?

Look over plastic plates and platters. Food grade right there, check for static potential nyuk nyuk.

ChrisTenone: Does dichloromethane not cause cancer outside of California?

I don't really know, the label mentions California ;)

Cali sets a stricter standard on warning labels. If a product might get sold there, it must have the label.

City water here is well likely worse than that and new heaps of mining tailings are left up-river now as the Bush-era heaps are getting leached out.

It’s called Prop 65 labeling. Some is a bit nonsensical, but overall, good stuff. Here is the final word.

It looks like they'll be putting the same warning on coffee in CA.

If you breath too long, you will die.

Or how about putting warnings on water. It's the deadliest chemical in the world. Not only is it poisonous when taken in too much, it kills millions every year in different ways (mostly floods and other drownings). When I hear about those law suits I'm always wondering, is the one asking for such a warning serious, or are they trying to show the ridiculousness of the whole thing.

Sometimes, I think it's all about justifying ones job.

pert: It looks like they'll be putting the same warning on coffee in CA.

Right. As I understand it, DCM (a cancer-causing chemical according to CA Prop 65, which is determined by a careful analysis coupled to highly protective standard of protection) is used in the decaffeination process. Personally, I avoid as many chemical (etc.) changes in my food as possible.

This is actually about a different carcinogen called acrylamide which is generated during the roasting process and so is found in all coffee, rather than decaffeinated coffee specifically.

Now they’re talking about civil penalties for the big coffee sellers of up to $2500 per person for each day they drank coffee over 8 years!