Circuit Prototyping using Copper Tape

This blog post walks through one method for prototyping electrical circuits.  It revolves around using prototyping boards, copper tape, and thin insulating tapes and wires.

Here's an example:

The example above was built on copper-clad board, but other types of boards can be used too:

The copper-clad board is great for whenever a ground plane is desired. It comes in single-sided and double-sided variants. I use double-sided which can be sometimes convenient.

The tools and consumables required are shown in the photos below. What is not shown is the soldering iron and the head-mounted magnifier, and both of those are important too. I used a 1 mm tip soldering iron (even for soldering to the large area of copper), but this requires an iron with the heating element within the tip itself probably. For soldering irons with an indirectly heated tip, a larger tip will likely be needed.

The wire strippers and wire are quite special. The Kynar or Tefzel or PVDF wiresPVDF wires have insulation that will not shrink or melt when soldered. The wire strippers can be used to strip extremely tiny lengths of such 30 AWG sized wire. In the photos below, the wires were 15mm length, and after stripping around 2.5 mm from each end, only around 10 mm of insulation remained. This isn't easy to do with other wire strippers. With the Stripmaster Lite 45-672Stripmaster Lite 45-672 tool, such small wires can be stripped by holding the wire with tweezers and inserting into the tool. The wire and wire strippers are simply brilliant for prototyping. Here's another example, this time showing how to solder pads underneath a chip or module. The wire is silver plated and solders easily. It means it is possible to tin the wire and pad first, and then hold the wire with one hand and the iron with the other, and just rely on remelting the solder to make the bond - with no additional flux. This would be controversial usually, but I think for prototyping it is ok.

The photos below show how a pin header could be soldered to copper-clad board. Polyimide tape (also known as Kapton tape) is heat resistant, and is ideal for insulating portions of the board.

The Polyimide tape can be used together with the copper tape to produce thick tracks, suitable for carrying power to other parts of the circuit.

Typically you could use surface-mount integrated circuit (IC) prototyping boards for each chip, then mount them onto the copper-clad board and route power to each board using the copper tracks, and interconnect the remaining signals using wires. You can also solder simpler parts directly to the copper track, as shown in the following photos. Here a resistor and LED are connected to supply and ground:

For soldering ICs, as mentioned IC prototyping boards could be used. If you don't have that, then the polyimide tape comes in handy again!

Here's the finished example board. A common scenario is that a 100 nF capacitor is required across the power rails for ICs. The photo below shows how that is achieved.

Once I'm happy with the circuit, sometimes I'll use epoxy glue to make some of the larger components or wire leads more secure. The result is more than good enough for prototyping, before ordering a printed circuit board.

That's it! There are plenty of variations that could be tried. Some people mount the ICs upside-down (known as 'dead bug' construction). Sometimes isolated areas are required and a knife can be used to cut the copper and peel it out, and one variation does that using a special drill bit to cut copper disks.

Thanks for reading!