As I was admiring the function and build of one of the products that we build, I started reminiscing on how far electronics have come in my career. With that, I thought that a look back might be nostalgic to some of the other old-timers, interesting to some of the newer people and inspirational to those of us that wonder what could be next. To get into several areas of electronics and not make the reading too long at one time, I broke this into 4 sections:
Part I: Electronics Manufacturing Review
Part II: Schematics – Then and Now
Part III: PCB Design – Then and Now
Part IV: Electronics Assembly – Then and Now
Since anyone can do a search on what it was way back when, I decided to keep this from my own personal experiences instead of an everything-included article, which could easily turn into an entire book. To give a frame of reference, I started working as an electrical engineer in 1984 on F-16 radars, moving on to identification friend or foe (IFF) systems, postal systems, portable radios, a brief stint with LTE, and now at ACDi, a contract manufacturer that makes a wide variety of electronics for many customers. Looking further back, I think what got me interested in electronics in the first place was going with my father to the local Radio Shack with a bag full of tubes from our television to test them and see which ones were bad.
1984 – A Look Back
Computers – We did not have personal computers yet. The only thing resembling a computer was a terminal that was connected to a mainframe in some air-conditioned room in a place that none of us ever saw. There were 4 terminals placed on tables that about 20 of us shared. They really were not useful at all for anything we were doing. If anything, they were something to get us used to what was to come. A few years later, we finally got one IBM PC to share between the 20 of us, which I believe cost about $15k. That meant only the boss and project leads ever got to use it.
We did have Hewlett-Packard (HP) computers which we were able to use to write automated test software. All the HP computers included their version of HP Basic, which was HP’s version of Basic that they upgraded over time. One of the early ones was an HP9825 which only had volatile RAM and no hard drive and a cassette tape as its media. The memory was so limited that we had to use several cassettes to complete a test on each unit. Its display was a single-line display, and it had a built-in printer that printed on paper the size of a store receipt. That was quickly upgraded to several other HP computers which added lots of memory, bigger displays, and cabled connections to dot matrix printers.
Communications – Since PCs were not cost-effective or prominent yet, there were no emails and no word-processed documents. Except for a few typed items (there was also only one electric typewriter), almost everything was handwritten. Since there were no emails yet, the way to get a message to the team was to put a memo in an interoffice envelope, with a distribution list on it and it would start its journey, sometimes taking a week for everyone to see it.
Electronics Manufacturing – Surface Mount Technology (SMT) existed but was barely used at the time. For the sellable products, everything was through-hole, and with a few exceptions, was only on one side of a 2-layer board. The secondary side was mainly used to make connections where needed, like breadboarding today. SMT was starting to be talked about, but most of us did not think it would be reliable enough and that you needed to have the strength of a component being soldered to a board to stay in place. Another problem with migrating to SMT was that the workforce was only trained on through-hole technology and would need to be trained on SMT processes and techniques.
The test equipment that we used was typically a 3-bay 18” rack, 6 ft. tall console. It had lots of HP test equipment in it (HP was the premier test equipment supplier at the time), as well as some custom-made electronics and a computer. The custom-made boards were wire-wrap boards that consisted of an array of integrated dual-in-line packages (DIP) and component carriers that resistors and capacitors were soldered to. The back side of the board was a rat’s nest of 30 AWG wires that were wire-wrapped to pins on the back of the boards. These boards were great for prototyping – I wish they were still commonly used.
The integrated circuits (IC) were almost all 5V TTL logic gates and some analog circuity like op-amps. 3.3V CMOS was starting to enter the landscape but they were very sensitive to ESD damage, so we tried to avoid them if possible. One of the benefits of this limited IC availability is that designs were kept simple and easier to troubleshoot. Microprocessors and microcontrollers were available, but we did not commonly use them, instead we used TTL logic to control our circuits.
Transitioning to SMT
As computers became more commercially available, more engineers became trained on how to design and program them, and because of that also became familiar with microcontrollers and microprocessors. Initially, they were still DIP packages and could be through-hole soldered. These components have a lot of supporting circuitry like memory, oscillators, resistors and capacitors, and still needed a lot of power. The industry worked to reduce circuit spacing within ICs as much as they could which helped to reduce power and increase functionality. These SMT packages also allowed a lot more components to be put onto a board. They also increased the number of signals to connect, which made multilayer PCBs more commonplace.
Moving to SMT was a huge investment. Staff had to be trained. Microscopes had to be purchased to let the staff see what they were soldering. Initially and briefly, boards were designed to be mostly through-hole, but with provisions for a few SMT components. It was quickly realized that automated SMT pick-and-place machines were going to make PCB assembly more efficient and repeatable. It was a huge up-front investment but would quickly pay for itself.
Today’s Electronics Manufacturing
SMT technology is in widespread use. The only time through-hole technology is used is typically for large components or other components that need good mechanical strength like connectors. Ball grid arrays (BGAs) even have leads that get soldered under the component. Automated Optical Inspections (AOI) and X-ray inspections are commonly used to ensure PCB assemblies were built correctly. ICs are rarely discrete TTL logic gates but are typically entire functions on a single IC. PCBs are almost always multi-layer boards, sometimes 20 or more layers. These include controlled impedance lines, instead of having to use a coax cable. Thousands of components are often placed on a single board instead of dozens. Power requirements are significantly less.
All these changes have forced electronic tools and processes to improve. Some of the primary ones are schematic capture, PCB design, and electronic assembly – subjects for another article. Stay tuned!
Engineering Program Manager