Issue link: https://iconnect007.uberflip.com/i/1453746
FEBRUARY 2022 I PCB007 MAGAZINE 101 any case they should learn the fundamentals of soldering documented in the enclosed 'Hand- book.'" is turned out to be a 12-page pam- phlet purporting to be "all you need to know about soldering." I have never been so angry, before or since. I thought it was a legitimate question and deserved an answer. For exam- ple, "We don't recommend soldering to gold," would have worked. I threw the letter and "Handbook" into a wastebasket, then retrieved the letter, tore it up, and threw it back into the wastebasket. I considered taking the wastebas- ket out to the parking lot and setting fire to it. I did not write to either company to thank them for their help. e third letter was sent to Alpha Metals. e head of marketing got the letter and, as he told me later, decided something was happening at HP, and they needed to find out about it. He made an appointment, flew to San Francisco, collected the local representative, and came to see me. I explained my problem and, instead of laughing or insulting me, he suggested we look at a new solder that their chief technolo- gist, Howard Manko, had developed and pat- ented. (Howard later contributed five chap- ters on solders and soldering to the first edi- tion of the Printed Circuits Handbook.) is alloy was also advertised to be less prone to developing dross and made (so they told me) a more consistent joint. In addition, the solder pot did not have to be cleaned and the solder replaced as oen as the present alloys. He also suggested we consider a new flux developed by the Battelle Memorial Institute based on uric acid, which was very aggressive and would clear inorganic contaminants from almost any metal being soldered and ensure the sol- der would only deal with joining metals. is one-two punch sounded almost too good to be true. Instead of the Lone Ranger coming to the rescue, I was now concerned that I was deal- ing with Professor Harold Hill of "e Music Man," selling me a boys' band. However, it was the only game in town at the time. As a result, I got a purchase order for both and started to try to understand if this was leading me into the assembly process of the future or another HP printed circuit reliability disaster (and unem- ployment). e biggest plus, from my point of view, was that there were no HP product designers or production engineers telling me I was mak- ing a mistake that imperiled the entire com- pany and offering advice I had to follow up. In this case, however, there might have been a point. With the strong acid flux, we had no choice but to use a water wash, and a rigorous drying process. e first thing we tried was a Hobart Kitchen-Aid dishwashing machine. We just treated the soldered boards like dirty din- ner dishes, and, aer the drying cycle, blew the remaining moisture off with an air hose that made very strong dry air blasts. ey also made a very high-pitched noise that attracted Bill Hewlett's attention. He felt the operators should not be subjected to that level of white noise, even with ear protection. We had mea- sured the level, but he was adamant. is resulted in a series of steps to protect the operators and eventually led to the design of an in-line soldering, washing, and drying machine that was quieter than the ambient environment. However, the washing machines did seem to do the job, and, in the interim, we had several. As part of all this, however, I also had to learn a lot about reliability testing. We did not want to be sending time-bombs to the customer. With the strong acid flux, we had no choice but to use a water wash, and a rigorous drying process.