Hybrid integrated circuits are one of the less well-known aspects of electronics. Hybrids combine active and often passive components on a substrate to form a single packaged module.

It used to be that hybrids came in two varieties, thin-film and thick-film, these terms referring to the 'films' of material that are deposited on the substrate to form both interconnects and passive components, on top of which further discrete components may be added. Nowadays the distinction between the two types is blurred.

Hybrids may be analogue or digital, and are often used in specialised or custom applications. They are rarely seen by the amateur electronics enthusiast.

One of the most important developments of hybrid ICs was made by IBM in about 1962. They were looking for a new circuit construction technology to use in their revolutionary System/360, a computer family that IBM wanted to be far in advance of the competition in both software and hardware. Integrated circuits were very new technology at the time, and IBM decided not to use monolithic chips, but to create a type of hybrid that they called "solid logic technology" or SLT. The small SLT modules used 'flip chip' technology, where transistors and diodes were soldered upside-down over a ceramic substrate, which bore deposited metal interconnects and thin-film resistors, with small copper balls used as both spacers and connections. IBM went on to develop denser packaging technologies using similar methods.

IBM slt module
STC hybrid circuit

This image shows quite a large hybrid device made by the former English semiconductor manufacturer STC, who were owned by ITT.

The Ferranti company made the 1200 series of hybrids in their LCE "Logical Circuit Elements" family. These are well documented in the book "Anglo–American Microelectronics Data 1968–69: Manufacturers A–P" edited by G.W.A. Dummer and J. Mackenzie Robertson. Parts of this treasure trove of data on early ICs can be viewed on Google Books.

These are hybrid digital logic circuit elements made up of thin film passive elements and discrete planar silicon semiconductors. The image shows the FF1201 single JK flip-flop.

Ferranti FF1201 hybrid circuit

I have come across a number of Intellux devices, such as this FF2514B, that use identical technology to the Ferranti LCE 1200 series. These are described in another Dummer and Mackenzie Robertson book:"American Microelectronics Data Annual 1964–65" on Google Books, as well as in their price list from March 66, available in the Internet Archives. Intellux were an American company and they marketed an extensive set of such devices as their "H series" and possibly others. These have part numbers similar to the Ferranti devices, but there are none common to the two manufacturers. Interestingly, the 1964 book gives the transistor types used in the Intellux hybrids: 2N708, 2N711 and 2N2369.

The description of the Intellux hybrid technology in these documents is word-for-word identical to that of the Ferranti ones. Ferranti and Intellux therefore MUST have had a close commercial relationship, but which created the circuits and which licensed them? If you can clarify this situation, please

Intellux FF2514B hybrid






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