Page "IBM Solid Logic Technology" Paragraph 1

Solid Logic Technology ( SLT ) was IBM's method for packaging electronic circuitry introduced in 1964 with the IBM System / 360 series and related machines.

IBM chose to design custom hybrid circuits using discrete, flip chip-mounted, glass-encapsulated transistors and diodes, with silk screened resistors on a ceramic substrate.

The circuits were either encapsulated in plastic or covered with a metal lid.

Several of these were then mounted on a small multi-layer printed circuit board to make an SLT module.

Each SLT module had a socket on one edge that plugged into pins on the computer's backplane ( the exact reverse of how most other company's modules were mounted ).

SLT was a revolutionary technology for 1964 with the reliability improvements over other assembly techniques helping propel the IBM / 360 mainframe family to overwhelming success during the 1960s.

SLT research produced ball chip assembly, wafer bumping, trimmed thick film resistors, printed discrete functions, chip capacitors and one of the first volume uses of hybrid thick film technology.