We like retro-computing and we like open source standards that allow easy project sharing. Vintage DEC computer enthusiast [Jay Logue] combines both of these in his recent project on GitHub, where he shares several KiCad templates for making your own Flip-Chip modules. Although named after the semiconductor packaging technique we are familiar with today, DEC Flip-Chips were introduced in 1964 as a modular electronics packaging system. These were used in many of DEC’s Programmable Data Processor (PDP) computers, beginning with the PDP-8 in 1965. DEC also had a Digital Laboratory Module family, which was a roll-your-own custom electronic system. The 1968 Digital Logic Handbook shows the available modules, and has the look and feel of the TTL Cookbook book which would come along six years later.
Flip-Chips came in a variety of sizes over the years: single-, double-, and quad-, and hex-height boards having standard- and extended-length. The PCB’s have 18 gold-plated fingers on one edge, later extended to 36 fingers double-sided, which plug into a backplane. Interconnections were typically wire-wrapped. A single height board is 127 x 62 mm (5 x 2-7/16 inches) with a labeled extractor bracket on one end. [Jay]’s repository has templates for five of the most popular variations, and making other sizes should be straightforward using these templates as a starting point.
While we pack a lot more functionality in similarly-sized circuit boards these days, many systems still use a modular design not unlike the Flip-Chips from over 50 years ago. Do you have any recollections of using Flip-Chips, or are you using them today? Let us know in the comments below.