Hewlett-Packard’s Adoption—and Controversy—of Plated Through-Holes

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In this issue of Design007 Magazine, we’re taking time to reflect on the development of PCB technology since the first episode of Star Trek aired in 1966. I believe that it is instructive to remember just how close Hewlett-Packard—and likely the entire industry—came to adopting eyelets instead of plated through-holes in the early 1960s.

Except for the transistor, no other technical development of the 20th century has had such a profound impact on all aspects of daily life as the plated-through-hole (PTH) printed circuit. In its role of interconnecting digital components reliably, cheaply, and universally, it makes possible all the wonders of modern life that utilize the transistor.  

That there was ever a controversy over the use of plated through-holes as an acceptable printed circuit interconnection process seems almost impossible to consider, let alone take seriously today. But in the late 1950s and early 1960s, the PTH was not just a controversial idea; serious product designers considered eyelets a preferred technology. It became a competition, and people took sides. It was a slow week if Electronic News, a very important industry publication at the time, did not print an article reporting a new study, or just quoted a learned opinion, on the benefits or perils of one versus the other.

Hewlett-Packard was not immune to this controversy at the time. In 1959, HP was still recovering from the misuse of single-sided boards in a new product. The poor reliability of that instrument had not only done serious damage to the company’s credibility on quality and reliability, but had caused serious financial issues on rework, repairs, and lost sales. At this point in time, major electronics companies such as Sylvania Television and Tektronix Instruments were actually advertising that their products did not use printed circuits. In response to this problem, HP had turned to eyelets to solve the immediate issues, and that did have a benefit for those single-sided boards. A bigger problem, however, was looming as all the new products were to be designed with transistors, which meant that both sides of a board would be needed.

Young Engineer, Risky Project
That’s when, and where, I came in. I was a newly hired electrical engineer tasked with bringing the company into a printed circuit technology that would be an advantage to the product and perceived as such by the customer. To illustrate the level of misunderstanding of the real problem, it was viewed as an electrical engineering issue because it was dealing with interconnecting electronic components and circuits rather than the mostly chemical engineering challenge that I soon found it to be. They had the wrong person. However, I had the job.

After some stress tests on both eyelet boards and plated through-hole sample boards, I became convinced that the only process that could achieve company reliability and cost goals was the plated through-hole. Getting others at the company to agree with me, even given my test results, was a much bigger problem than I ever imagined. Coming off the previous experience with printed circuits, product engineers did not want to abandon eyelets, since they were now working, and insisted on refining that process to the new double-sided need. Their argument was, basically, that “plated through-hole” was absurd on the face of it. How could any reasonably sane person expect to plate copper in hundreds of small holes, drilled in a nonconductive material, and not have many fails? I actually had three senior technologists each provide me with information on separate eyelet processes they insisted would work.

To read this entire article, which appeared in the June 2021 issue of Design007 Magazine, click here.



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