Handling Sensitive Computer Parts

Most ECU and other computer “black boxes” are plug and play devices, but in some cases it makes sense to go in and change a PROM or track down a loose ground or cold joint. If you’re going in, however, keep a few things in mind. One is the damaging effect of heat. Use a low-wattage iron, preferably 25 watts, but not more than 40 (and never a gun), and use a heat sink wherever possible. Simply soldering about 10 cm of heavy copper wire to an alligator clip can make a good one for fine work. Attach the heat sink near the joint to be soldered to protect components. Always use resin core solder, and choose the thinnest you can find for delicate work. Thinner solder melts faster and gives greater control without the risk of leaving globs of excess. If those silver balls do form, don’t leave them inside the case, or they will find their way across two terminals. If you’re trimming leads on components, consider using a scissoring cutter instead of the traditional diagonal pliers. The dikes send a shock up the lead and into the component, potentially fracturing transistors or chip substrates. Notice the force with which the cut end flies off when you cut? The same force travels upward into the component. It doesn’t always cause damage, but the more expensive the component, the more powerful becomes Murphy’s Law.