Process-Level Problem Solving on the Factory Floor

“After observing this soldering work for a few days, I felt it was not a very good technique, because the soldering tool’s temperature was very high and the operators’ experience and skill levels varied. Some new operators had to keep the soldering tool in contact with the electrode for quite a long time before completing the soldering, and the high temperature of the soldering tool was very likely to affect the chemical structure inside the transistor as a result.”

“I dug out the heat transfer textbook I had studied at MIT and did some rough calculations, and found that my concern was correct. So over the next few days, I tried an indirect heating method: not letting the soldering tool directly contact the electrode, but only letting it contact the copper wire, using copper’s high thermal conductivity to melt part of the electrode and complete the soldering. My method was slower than the original, but the likelihood of disrupting the transistor’s internal chemistry should be lower than with the original method, so the final yield should be higher. After I myself became proficient in operating my soldering method, I began training the two most experienced operators. After one or two days, their soldering speed using the new method had reached 80–90% of the original method. We accumulated several hundred transistors soldered using the new method and compared the yield with another group of transistors soldered using the original method. Sure enough, the yield of the new method was noticeably higher than that of the original method. My supervisor came over to take a look, and the production manager also came to see it, and even sat down and asked me to teach him the new soldering method. A few days later, the entire production line switched to my method.”