some breadboards

Depending on process I generally switch from CMOS to PECL at around

500MHz... choice made from power consumption cross-over. I wouldn't run discrete CMOS packages that fast... power to drive the pin and trace capacitance really adds up in a hurry. ...Jim Thompson

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What do you use to remove the copper cladding? John Ferrell W8CCW

Usually an x-acto knife. To remove a large strip, cut the edges, tin a corner, heat with a soldering iron, and peel up the copper with tweezers as you slide the tip along. A dremel is good too. Teflon boards are especially easy to cut and peel.

After it's hacked, rub hard with a piece of Scotchbrite. That removes the copper burrs and polishes it up for soldering. Avoid fingerprints; they will corrode the copper in a few days and make ugly spots.

You can do some fun stuff with kapton tape, too.

John

Please elaborate. This sounds like fun!

Here's an EclipsLite gate driving a phemt. The SO-8 sits on a piece of kapton tape with cutouts for the leads that solder to copper. Nice and planar. Two ugly fingerprints. I really need some gold-plated copperclad.

ftp://jjlarkin.lmi.net/BB_fast.JPG

You can build multi-GHz stuff, with Digikey parts, this way.

John

What are those insulated standoffs along top of PCB called?

I prototype power stuff on copperclad, usually glue small pieces of PCB for isolated connections, the things you're using look easier?

Thanks, Grant.

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Insulated standoffs! I got a bunch of them at some surplus store.

I also like old-teevee-set type phenolic terminal strips, which you can still buy.

That's a nice idea, but you do have to glue them down, and the glue tends to pop off the copper.

A 22M resistor makes a pretty good standoff.

Some sort of dremel circle cutter, like a tiny hole saw thing, would be cute, to cut isolated circles.

John

You can buy small hole saws intended for cutting stone and tile. They're metal tubes with industrial diamonds on the cutting edge.

I got a set, quite expensively, from an eBay seller (a Chinese manufacturer of them, I believe). They make decent pad cutters for simple PCB circuits.

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Have you thought about getting one of these ? I would love one

We had one, at least a similar version. One of our customers gave it to us because they thought it was a silly PITA. We soon agreed. It's so much easier to lay out a proper plated-through board, multilayer if you need it, and order it quick-turn.

John

Is that the only reason you use Kapton (I presume it's 2-sided)? To hold parts in place better than CA or such?

No, it's just a one-sided insulator, but it stands up to solder.

Kapton tape+copper tape = capacitor or transmission line

Glues (hot melt, CA, epoxy) tend to not stick to copper for long. Solder is the best adhesive for copperclad.

John

How about spraying flux on the board first to keep the copper from corroding?

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You don't use any adhesive? Just anchor the GND pin to copper? (And, I presume, some N/C and unused inputs, too...)

Messy! For small pieces, you can scotchbrite them, coat them with diluted flux, and slide a big soldering iron around to tin the whole surface. It really doesn't take long. But then wash the sticky flux off.

I did part of this board that way:

ftp://jjlarkin.lmi.net/Sampler1.JPG

John

That's actually a bad idea. Most fluxes range from acidic to corrosive, even natural rosin products -- rosin is a mixture of organic acids, so they will attack copper slowly (over years).

Ironically, I've never had fingerprints corroded into anything of mine. I've heard that some people have the inverse-midas touch. I don't seem to have it. My fingers just make ordinary sebum (skin oil), which as an oil, is an excellent protector of metal, not a corrosive :-)

If you want to be really fancy, a coating of light oil (mineral oil let's say) will keep your boards shiny, if not completely streak- or fingerprint-free, while still remaining solderable. A coat of spray lacquer will, of course, seal the surface nicely, but YMMV tinning it.

Tim

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It's probably the salt content of sweat that causes the etching. And that is a variable based on your diet.

If you favor salty foods, don't handle your boards... ;-)

That's the best way. Keeps everything planar.

Double-stick (picture-mounting-type) foam tape does stick to copper forever, but is too thick for picosecond stuff. I use foam tape to paste down the Bellin surface-mount adapters. Just be careful to not solder through it to the copper.

John

We have one at work here, and IMO it's not nearly as useful as you'd think: Its capabilities are nowhere near what commercial board houses can provide, and the coast of making a board are generally just as much if not more when you're paying people for their time (particularly if you want, e.g., plated-through holes).

Its saving grace is that you can have a board cut in a hours if you really need some relatively simple board right *now* -- while the commercial board houses can do work overnight, it commands a very significant premium, and you're still looking at at least 1 day and usually 2 or 3 depending on the exact timing.

With a good engineering process those situations should be pretty rare, though. (I've often felt that a good measure of how good a company's engineering process is would be to count the percentage of FedEx/UPS overnight orders they place from distributors...)

---Joel