Page 453 - Robot Builder's Bonanza

422 MAKING CIRCUIT BOARDS

The process of making your own printed circuit boards is not complex or even difficult, but
it is time consuming, and it does involve using some nasty chemicals that cause stains on
clothing and burns on skin. With the advent of low- cost PCB service bureaus, making your
own circuit boards is something of a dying artform. If you’re interested in the techniques used
to make your own printed circuit boards, check out the bonus tutorials about it on the RBB
Online Support site (see Appendix A).

Using Custom Prototyping Boards

The popularity of several brands of microcontrollers has spawned a kind of cottage industry
in prototyping (or proto) boards custom- made for them. Proto boards are empty PCBs with
layouts and predrilled holes to accommodate a wide variety of projects.
You start by soldering the microcontroller into its spot (better yet, use an IC socket, then
plug the controller into the socket), then complete the board by adding other components.
Many prototyping boards have a reserved section for general experimenting, where you can
add your own circuits to the basic one already there. Some proto boards are even made with
mini solderless breadboards stuck to them.

Some proto boards already have the microcontroller soldered to them. In this case, the
controller may be in a more compact format than the typical dual in- line package (DIP) you’re
G most familiar with. This makes using the board very convenient, as the controller is already
built in.
The disadvantage is that if the MCU is not in a socket, any damage to the chip means the
entire prototype board is a loss. My preference is to use a prototyping board that accepts the
standard DIP IC packages, and then use sockets to allow easy swapping of controllers.

Making Semipermanent Circuits

with Wire Wrapping

With wire wrapping there’s no soldering (or at least only very little); instead, plug a special
socket into a perforated board, and then wrap thin wire around the pins of the socket using a
special tool. The advantage of wire wrapping is that it’s relatively easy to make changes. Just
unwrap the wire and reroute to another post.
Wire wrapping is commonly used in IC- intensive circuits. The construction technique
doesn’t promote fast results, but because soldering is usually not involved it’s a safer bet for
kids interested in learning electronics. And, of course, mistakes are easier to correct than
when using solder construction.

HOW WIRE WRAPPING WORKS
To wire wrap, first mount a wire wrapping socket into the perforated board. Sockets are avail-
able for all the common sizes of DIP- style ICs. I prefer to use a perf board with copper pads
around the holes so that I can apply a tiny bit of solder to at least one of the pins of the socket.
This keeps the socket from falling out while I’m working on the board.

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