![]() Philco SB100 surface-barrier transistor advertisement The Explorer 1 satellite's payload, consisted of a low-power Microlock transistorized (radio beacon) 108.00 MHz transmitter, which was used for tracking and telemetry, and had consisted of a Philco high-frequency surface-barrier transistor in its original circuitry designs. ![]() On January 31, 1958, the United States first artificial Earth satellite was launched by the Army Ballistic Missile Agency at Cape Canaveral in Florida, which was called Explorer 1, and was developed by the California Institute of Technology Jet Propulsion Laboratory (JPL). Philco's SBDT improved surface-barrier transistor, was used in the early prototype design of the 10-milliwatt Minitrack satellite transistorized (radio beacon) transmitter, for the United States Navy Vanguard I satellite project program. The Philco SBDT transistor was capable of operating in the UHF range. Philco had used surface diffusion of a gaseous form of phosphorus atom particles, to penetrate the surface of the intrinsic semiconductor base material. In 1956, Philco had developed an "improved" higher-speed version of its original surface-barrier transistor, which was used in military applications and was called the surface-barrier diffused-base transistor (SBDT). In 1959, General Transistor Corporation had also purchased a license agreement from Philco, to manufacture its complete line of high-speed transistors. Another company to purchase a license agreement from Philco in early 1957, was Semiconductors Limited, a division of the British-based Plessey Company. Sprague Electric Company was one of the first companies to purchase a license agreement from Philco in late 1955 and started to manufacture the surface-barrier transistors under its Sprague name, in early 1956. Starting in 1955, Philco had decided to sell commercial manufacturing license agreements with other large electronic semiconductor companies, which allowed them the right to produce and sell its high-frequency surface-barrier transistors. Sprague surface-barrier (SB100) transistor licensed by Philco Corporation ![]() Philco Corporation had produced a late 1950s production film about its surface-barrier transistor manufacturing processes and product developments that was titled, " Philco Transistors - The Tiny Giants Of The Future". It was developed and produced at the Lansdale Tube Company-division of Philco Corporation. The Philco surface-barrier transistor was the world's first high-frequency junction transistor, which was capable of obtaining frequencies up to 60 MHz. After the etching process was finished, the polarity applied to the electrolyte was reversed, resulting in metallic indium being electroplated into these etched circular well depressions, forming the transistor's emitter and collector electrodes. This process would etch away and form circular well depressions on each side of the N-type germanium base material, until the germanium base material was ultra thin and having a thickness of approximately a few ten-thousandths of an inch. Philco used a patented process of applying two tiny electrochemical jet streams of liquid indium sulfate (electrolyte solution) on opposite sides of a thin strip of N-type germanium base material. ![]() ![]() Like the modern Schottky transistor, it offered much higher speed than earlier transistors and used metal–semiconductor junctions (instead of semiconductor–semiconductor junctions), but unlike the schottky transistor, both junctions were metal–semiconductor junctions. The surface-barrier transistor is a type of transistor developed by Philco in 1953 as an improvement to the alloy-junction transistor and the earlier point-contact transistor. Philco Surface Barrier transistor developed and produced in 1953 ![]()
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