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JUNE 2021 I DESIGN007 MAGAZINE 27 Getting to the point where the review with Packard was possible took almost two years. To start, the only electroless copper deposition process I could find was a product called Cop- perCold, which was basically unstable. When successful, there would be copper in the hole that provided a conductive surface for electro- plating the copper for the circuit; however, it le an interface between the base and depos- ited copper that required mechanical removal to ensure a reliable circuit. When it was not successful, it caused all the copper to drop out of solution at once. Shipley's Gene Weiner to the Rescue In early 1960, I had been working with CopperCold for some time, and all I was getting was puddles of cop- per at the bottom of the tank. Out of nowhere, I got a call from the HP lobby informing me that there was a representative of a com- pany called Shipley wait- ing to see me. I met the rep, Gene Weiner, who intro- duced himself and said he was there to solve all my plated through-hole depo- sition problems. I thought, "Yeah, right!" He said he had heard HP wanted to get into the plated through-hole business. He set up a miniature deposition line on my engineering bench and asked for a sample of the double-sided copper clad material we were using. He then proceeded to blow me away. It worked! I would do considerable testing on the deposited copper and its adherence to the base material, and I couldn't find any problems. So, I got Gene a purchase order, gathered all the CopperCold materials for disposal, and never looked back. Gene le and I didn't see him again for almost 20 years. It was like the Lone Ranger coming out of nowhere, solving the problem, and then riding off. (Who was that masked man?) e Shipley patented process had the ability to control the deposition of copper and create a structure that bonded with the base copper. Although some shops continued to remove the copper deposited on the surface, we at HP didn't have the need for that step. Copper deposition was the key step, but other steps pre- sented their own problems. For example, it was com- mon to panel-plate copper to the board and then apply a resist to the circuit pat- tern and etch away all the exposed copper. In addition, the standard copper plating solution was acid based and plated about twice as much copper on the surface as it did in the hole. An alternative process using pyrophosphate was a pH-basic solution and more difficult to control, but it plated much less copper on the surface for a given amount in the hole. e problem, besides control, was that a silkscreen resist of the day did not survive the high pH. We worked with a resist supplier to develop an appropriate resist and we were able to develop a process that would pattern-plate copper, put up to two mils of copper in the hole, and reduce our waste copper by about two thirds. I wrote a paper showing the total destruction of a board with a soldering iron but leaving the plated hole and attached cir- cuitry still intact in its original form. Since I was learning as I went, when I had