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BREADBOARDING

by Stuart Ball

Start ı Grounding ı Placing Copper Strips ı Power Wiring and Supply Bypassing ı Lead Wiring ı Test Points ı Surface-Mount Parts ı Other Tips ı Putting It All Together ı Other Techniques ı Sources and PDF

PLACING COPPER STRIPS

When you place the copper ground strips, you should burnish them with a hard, round object such as the back of a spoon to force the adhesive into contact with the board. Donıt use anything with an edge or you will tear the copper, and donıt apply so much soldering heat that the adhesive lets go from the board. Be careful when working with the copper; it works like tape, but the edges of the foil can be sharp.

This technique is effective and produces a low-noise ground that is suitable for most digital/microprocessor projects youıre likely to encounter. 3M makes copper tape intended for EMI shielding that will work (also available through Newark Electronics). This tape (3Mıs 1181 and 1194 series) comes on a roll with a peel-off liner. The tape is available in widths 0.25ı and wider. 3M also makes a tinned copper tape, the 1345 series.

Many hobby stores sell copper tape with the metalworking supplies. The 3M tape doesnıt seem to tarnish as much as the hobby store tape, but the hobby store tape is considerably less expensive. Whichever tape you use will need to be cut to the proper width. You can do this with a sharp knife or scissors.

Donıt try to use the copper tape to hold a lead on the board. The adhesive will eventually let go. If you have a component with some stress on it, punch a lead through the perfboard and bend the wire around the top, as shown in Figure 1.

Donıt try to use this grounding technique with aluminum or stainless steel tape. Solder wonıt stick to it.

For a low-impedance ground, you can cover the entire board with tape on one side, then cut out slots where component leads will go. This is more tedious and requires more care to avoid shorting, but it is nearly as good as a ground plane.

Although the sketches so far have shown vertical copper strips connected by horizontal ones along the edges of the board, other layouts are possible. If you are working with a lot of logic on a large board, you might want to add more horizontal strips for lower ground impedance. One of the advantages of this method is that you can put the grounds wherever you need them.

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