page_title: IBM Solid Logic Technology
hierarchical_section_title: IBM Solid Logic Technology
caption_attribution_description: English: Steps in manufacturing Solid Logic Technology hybrid wafers used in the w:IBM System/360 and other IBM computers of that era, starting in 1964. The process starts with a blank ceramic wafer 1/2 inch square (1). Circuits are laid down first (2), followed by resistive material (3). Pins are added (4), the pins and circuits are soldered (5) and the resistors trimmed to the desired value (6). Then individual transistors and diodes are added (7) and the package encapsulated (8). Display at the Computer History Museum. "Gift of Mike Turin" [1]
context_page_description: Solid Logic Technology 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, forming an SLT module. The circuits were either encapsulated in plastic or covered with a metal lid. Several of these SLT modules were then mounted on a small multi-layer printed circuit board to make an SLT card. Each SLT card had a socket on one edge that plugged into pins on the computer's backplane.
  IBM considered monolithic integrated circuit technology too immature at the time. SLT was a revolutionary technology for 1964, with much higher circuit densities and improved reliability over earlier packaging techniques such as the Standard Modular System. It helped propel the IBM System/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.
context_section_description: 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, forming an SLT module. The circuits were either encapsulated in plastic or covered with a metal lid. Several of these SLT modules (20 in the image on the right) were then mounted on a small multi-layer printed circuit board to make an SLT card. Each SLT card had a socket on one edge that plugged into pins on the computer's backplane (the exact reverse of how most other companies' modules were mounted).
  IBM considered monolithic integrated circuit technology too immature at the time. SLT was a revolutionary technology for 1964, with much higher circuit densities and improved reliability over earlier packaging techniques such as the Standard Modular System. It helped propel the IBM System/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.
  SLT replaced the earlier Standard Modular System, although some later SMS cards held SLT modules.
caption: Steps in manufacturing Solid Logic Technology hybrid modules. The process starts with a blank ceramic wafer, 1/2 inch (12.7 mm) square. Circuits are laid down first, followed by resistive material. Pins are added, the circuits are soldered and the resistors trimmed to the desired value. Then individual transistors and diodes are added and the package is encapsulated. Display at the Computer History Museum.
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