Issue link: https://iconnect007.uberflip.com/i/1527613
72 DESIGN007 MAGAZINE I OCTOBER 2024 a designer to create an integrated circuit with the least number of transistors necessary. I also wrote more recently that my first "integrated circuit" consisted of six transistors soldered to and functionally integrated by a printed circuit in 1957, a year before Jack Kilby invented the IC. High-performance computing and military applications primarily utilized ceramic mul- tichip modules (MCM-Cs) in situations where space and performance were critical. Ceramic was brittle but also highly resistant to heat and mois- ture. Following the lead of military product develop- ers, the commercial world adopted the idea of the MCM but used organic laminates and PCB fab- rication technologies to create the products (MCM-Ls). Chips were typically attached using metal-filled epoxies, and wire bonding technology was used to make inter- connections between chips. Both technolo- gies used solder to attach discrete devices, but ceramic allowed the designer to form resistors and planar capacitors on the device during fab- rication—a technique that was ultimately repli- cated for the organic laminate users. e technology behind MCMs matured in the early 1990s and advancements in semi- People have been using high density inter- connection (HDI) technology since the early 1980s, although it was not called HDI until the late 1990s. In the 1970s, '80s, and early '90s, engineers used HDI methods to develop hybrid circuits, which were later referred to as mul- tichip modules (MCMs). ese were arguably the first instantiation of heterogeneous inter- connection technology, which has been the industry buzzword for almost a decade. ese devices are a way of inte- grating multiple chips— both integrated circuits and discrete devices (resistors, capacitors, and inductors)—into a single package, typically using ceramic substrates with layers of insulation and metallic inks (oen gold) and firing them at high temperatures. e intent was to enhance the performance and reduce the size of elec- tronic systems—a theme that has been a constant in the electronics manufacturing world since day one. If it hasn't dawned on you yet, there are echoes of those early efforts in what are now called "chiplets" in the "new" heteroge- neous era. I wrote an article about LEGO-like packages almost 30 years ago. Around 2013, I suggested that chip scale packages could be used to package IP blocks, which would allow Musings on High Density Interconnections Flexible Thinking Feature Column by Joe Fjelstad, VERDANT ELECTRONICS