IBM MCM Technology

In its heyday of computer design, IBM not only had great electronic technology but their packaging was unbelievably good. Here are some examples in the museum.

IBM Thermal Conduction Module (TCM)

Figures 1-5 shows the IBM TCM used in the 3081 computers, circa 1981. It is six inches square and weighs about 5 lbs. The outside of the cover is shown in Figure 4. The reverse side of the cover is Figure 1 which contains an 11x11 array of spring-loaded copper slugs. Figure 5 shows a side view of the cover and slugs (I have lost some of the springs so some of our slugs don't pop-up). When the cover is mounted on the bottom assembly, the copper slugs each press one one of 11x11 flip-chip mounted gate-array TTL chips, each containing about 704 circuits. The chips are mounted on a thick ceramic substrate containing 33 wiring levels. The back side of the ceramic, shown in Figure 2, contains 1800 I/O pins.

The area above the copper slugs in the cap was filled with helium to help conduct heat to the cover. The cover was attached to a water cooled plate.

IBM 3745 Thermal Conduction Module (TCM)

IBM Z9 MCM

Okay, so this is not exactly an old item: it was shipped in 2006. It does, however, show another instance of IBM's great technology capability, so since I'm covering older technology I thought it belonged—it's just so cool!

This is a processor module from the IBM Z9 mainframe/super server. There are 8 processor chips, each containing 2 cores, each with 256KB of L1 cache, along with 4 L2 cache chips comprising 40MB, plus controllers for cache, memory, and I/O. About 4.5 billion transistors altogether with a very impressive package.

The ceramic package has 102 internal wiring planes, 5,184 total pins including 2,970 signal pins. It dissapates 1200 Watts of heat and is normally water cooled, but there is a air-controlled backup where the clock speed is reduced.

The Z9 chips are implemented in IBM 90nm technology. Interestingly, we used that same technology for a processor design we did in the mid 2000's. Our tiny chip (about 30M transistors) could run at 2.0 GHz. The Z9 processor chips run at 1.7GHz. This is a tremendous achievement considering how much larger the Z9 is than our processor (150x spread across 16 chips!).