Beat The Soldering Blues From Transpo’s Rebuilder’s Forum Soldering diodes or voltage regu- lator repair chip connections may ap- pear to be a simple, mundane task that anyone can do. The truth is that just about anyone can solder, but it takes a certain amount of training to solder correctly. Without an adequate level of understanding, the otherwise simple task of soldering may even appear to be successfully accomplished even though the hidden results are disas- trous. The right solder. The unseen sili- con chips contained within the diode assembly and the components surface- mounted on repair circuits are set into place and electrically connected by solder. The starting point to soldering diodes or repair circuits into place is to use a solder that will flow at a lower temperature than that which is used in the diode or the repair chip. We rec- ommend Sn55Pb45 alloy solder for installation of diodes and repair chips. This is commonly referred to as 55/45 or 55 percent tin and 45 percent lead. The right tools. While a high tem- perature range soldering iron witha chisel tip is acceptable for some sol- dering jobs, it is not the right tool for soldering a repair chip into place. Set up different soldering stations, several if necessary, as dictated by your op- erations. A controlled output solder- ing station with a pencil tip iron is rec- ommended to achieve the best results when soldering repair chips. The right technique. Even with the right solder and the right equipment, diodes and repair circuits can be de- stroyed by wrong technique. The key to technique is dwell time. Apply the heat only as long as necessary to cause the solder to flow. Keeping the solder- ing iron applied longer does not en- sure a better soldering job. On the contrary, it almost ensures destruction of the part by causing the internal sol- der connections to re-flow and fail. We also strongly recommend us- ing flux when soldering. Many spurn the use of flux because it can leave an unsightly residue on the soldered sur- face. The residue is, however, inert and does not become a part of the joint. It is important to understand the function of the flux. All common metals are cov- ered with an oxide film. This film in- hibits solder flow. Flux removes the oxide film, allowing the solder to form a good joint between the two surfaces. Keep it clean. Use the following guidelines to keep your soldering area clean: – Leave your soldering iron in its cage and clean the cage daily. – Keep aclean, wet wiping sponge at your soldering station. – Remove and clean the solder tip daily. – Re-tin the iron tip any time the iron has been idle for more than 10 min- utes. – Clean the inside of the iron shaft with a pipe cleaner at least twice a month. There is much more to learn about soldering, but these basics are essen- tial to success. Review this article with your employees and apply the prin- ciples throughout your shop. Then watch your efficiency and product quality improve. NOVEMEBER/DECEMBER, 2000 Page 1 of 1