Patent GB-947271-A (GB)
Title: Improvements in or relating to electrical capacitors and methods for their manufacture
IPC: H01G4/245
Filed: 1962-08-09
Abstract: Capacitors are produced by forming chemically a thin dielectric layer or film of silicon dioxide or silicon nitride in intimate contact with conductive materials which act as electrodes. For example, tantalum foil is coated with a silicon dioxide layer by passing an organooxy-silane, e.g. ethyl triethoxy silane over the substrate at a temperature of about 750 DEG  C. Silicon dioxide is deposited on the substrate in the form of an adherent flexible layer, which is partially removed so that a metal tab electrode may be attached to the metal substrate, and then a further metal coat is applied by metallization. Other suitable ethoxysilanes are listed, and other suitable substrates are germanium, molybdenum, tungsten or platinum. A further method of coating the substrate consists in depositing silicon on the material from a gaseous mixture of hydrogen and silicon tetrachloride, followed by oxidation.  In this method the saturated gas is passed through a liquid cooled tube containing a tantalum tape heated to 850-1300 DEG  C., so that the silicon tetrachloride dissociates on the tape in a polycrystalline form. This deposit is then converted to silicon dioxide by oxidation, e.g. with oxygen gas or steam.  If a silicon nitride deposit is being applied, nitrogen is mixed with the silicon tetrachloride gas passed initially through the tube. Another described method for depositing silicon dioxide on the substrate is to evaporate silicon monoxide on to the substrate followed by oxidation. The coated substrates may be incorporated into rolled or stacked capacitors, and the assembled capacitors may be coated with further layers of silicon dioxide.ALSO:Capacitors are produced by forming chemically a thin dielectric layer or film of silicon dioxide or silicon nitride in intimate contact with conductive materials which act as electrodes. For example, tantalum foil is coated with a silicon dioxide layer by passing an organo-oxy-silane e.g. ethyl triethoxy silane over the substrate at a temperature of about 750 DEG C. Silicon dioxide is deposited on the substrate in the form of an adherent flexible layer, which is partially removed so that a metal tab electrode may be attached to the metal substrate, and then a further metal coat is applied by metallization.  Other suitable ethoxysilanes are listed, and other suitable substrates are germanium, molybdenum, tungsten or platinum. A further method of coating the substrate consists in depositing silicon on the material from a gaseous mixture of hydrogen and silicon tetrachloride, followed by oxidation.  In this method the saturated gas is passed through a liquid-cooled tube containing a tantalum tape heated to 850-1300  DEG C., so that the silicon tetrachloride dissociates on the tape in a polycrystalline form. This deposit is then converted to silicon dioxide by oxidation, e.g. with oxygen gas or steam.  If a silicon nitride deposit is being applied, nitrogen is mixed with the silicon tetrachloride gas passed initially through the tube. Another described method for depositing silicon dioxide on the substrate is to evaporate silicon monoxide on to the substrate followed by oxidation.  The coated substrates may be incorporated into rolled or stacked capacitors, and the assembled capacitors may be coated with further layers of silicon dioxide.