The method described here requires all the holes in the ground plane to be made before the electronic components are placed, so the circuit layout needs to be planned in advance. The picture shows an example of a circuit I built using this technique.
Step 1: Make All Breaks in Copper Strips.
TIP: Finger sweat will corrode the copper strips, so you may want to wear latex gloves when handling the board.
Step 2: Apply Adhesive Copper Foil to the Component Side of the Board
Step 3: Find a Correctly Sized Jewellers' Screwdriver.
The trick is to use a jewellers’ screwdriver that is slightly too big to fit in a hole in the board. The outer edges of the screwdriver should be supported by the edges of a hole in the board, but you should not be able to push the screwdriver into the hole. It is the outer edges of the screwdriver that will do the cutting. The top screwdriver in the picture is the correct size. The lower screwdriver is too small because it can be pushed through a hole. If you zoom in to the picture of the top screwdriver you will see that the sides of the blade are worn down slightly (probably due to all the cutting that I have done with it) and this actually makes it easier for the screwdriver to be supported by the holes in the board.
Step 4: Hole Cutting Technique: Stage 1 - Create Depressions
Step 5: Hole Cutting Technique: Stage 2 - Increase Pressure
Step 6: Hole Cutting Technique: Stage 3 - Remove Cut-out Pieces of Foil.
Step 7: Create Ground Vias and Solder the Foil Seams
To create a via between a strip and the foil, take a short fat piece of solid bare wire (1st picture) and push it through the foil and into the hole (from the foil side of the board). I use wire with a diameter that is the same as the hole. Push the wire as far as it will go into the board so that it is level with the foil. Then solder it to the foil on the top and to the strip on the bottom.
If you have used several strips of copper foil, then after all vias have been soldered in place, solder the entire length of the seam between overlapping strips of foil.
In all the soldering, try to make sure that the resulting foil surface is as flat and level as possible. The 2nd picture shows a ground via below the set of 9 holes, and the soldered seam.
Step 8: Apply Clear Adhesive-backed Plastic to the Ground Plane.
Stick a layer of clear adhesive-backed plastic over the copper foil (this is called “sticky-backed plastic” in the UK). It is sold in long rolls like aluminum cooking foil, and is available from stationary stores. The plastic is too thick to tear and it needs to be cut to size with scissors or a sharp blade.
I do not recommend using sticking tape as a substitute because it will be too thin, likely to tear, and in my experience the adhesive does not age well.
To make a hole in the plastic layer (so that a component can be placed), use a sharp needle to pierce the plastic from the component side of the board, and then gradually push the needle down fully into the board and wiggle it to widen the hole. DON’T USE A SCREWDRIVER OR BLADE TO DO THIS!!! The reason for using a needle (and not using sticking tape) is to avoid making a linear cut or tear. We need the plastic to line the entire rim of the hole, and a tear would prevent that from happening and could expose a portion of foil. The aim is to make sure that the plastic gradually curves into the hole and seals all the foil edges.
Step 9: A Simpler, But Less Reliable Method of Making Holes. (Useful As a "fallback" Option).
It is possible to place components without going through the procedure of cutting holes in the foil with a jewellers’ screwdriver.
The simplified process is this...
1) Make all necessary breaks in the strips. Check all holes are free of debris.
2) Apply adhesive copper foil to the component side of board.
3) Solder all vias between the foil and the strips. Then solder all foil seams along their entire length.
4) Apply clear adhesive-backed plastic to the foil.
5) To make a hole for a component leg, use a sharp needle to pierce both the plastic layer and foil layer in a single operation. Push the needle down into each hole and wiggle it to fully widen the hole.
I don't think it is as reliable a method since no foil is actually removed, and it is definitely not reliable if no plastic layer is used. However it is still useful to know that you can make holes this way as a “fallback” option.
For example, after you have soldered lots of components into the board you may discover that you accidentally forgot to make a hole in the foil at some location. It won’t be possible to remove the plastic layer and cut a hole in the foil (because components have already been placed through the plastic). So the only option is to pierce a hole through both layers in a single operation using a needle. That has worked for me on all the occasions that I needed to do it, but I have only done that around 50 times so I can't say how reliable it is. I have done close to 1000 holes using the "screwdriver method" and have never had a problem with accidental connections to the ground plane.
Step 10: Place Components and Solder Them
Both BEFORE and AFTER each component is soldered in place, use a multimeter to check for any unwanted connection between the component’s legs and the ground plane. If there is an unwanted connection, make sure the hole is fully widened with a needle, and bend the component leg away from the edges of the hole. If that doesn’t work, you can try to add an extra layer of plastic to the problem hole (since the original plastic may have torn so that there is an exposed piece of foil). I have never actually needed to do that though.