Through-hole components – Don’t Tack On

It’s how we ‘fine tune’ a circuit, or fix a mistake. Just grab a through-hole resistor and solder iron and ‘tack it on’ across an existing component or across traces. We have been doing it for a hundred years.

But you have to be very careful when doing this with a DPCB board.

DPCB printed conductor is very brittle when compared to copper photo-etched boards. In the days of through-hole, we would solder one end of the resistor or whatever, then just bend the other end toward its destination, hold it in place, and solder. Try this with a DPCB board, and the conductive trace at the first end will peel off, crumble, or just snap. So remember, when you have that urge to ‘tack on’ a component, you have to bend it into shape first.

Better yet, design your experiment / prototype PCB artwork to allow you to easily add or subtract components.

The whole point of DPCB is to make ONE board. Maybe revise it and make another. At this point in our design process we should not be concerned with the final size of the product, its weight, or, how it looks.

What I have started doing during PCB layout is to throw on an extra SMD pad or through-hole here and there. Around surface mount components, I might just copy & paste an extra 0805 footprint next to the necessary one. Then I will have that very convenient spot to ‘tack on’ something.

This is especially helpful to prevent fighting with amplifier oscillations. Admit it, you were in a hurry and you are not being super-careful with your layout. Or, we did not anticipate the problems that can be caused by the lack of a traditional ground plane layer in DPCB technology. So you may find yourself adding or changing capacitors to work around that problem so we can proceed with our circuit development.

So for us ‘old guys’ that are making the transition to DPCB, start making it a habit during PCB layout, to provide for component changes or addtions. It only takes a few extra seconds here and there and can prevent a lot of re-work later.

Leave a Reply

Your email address will not be published. Required fields are marked *