3-Terminal TO-64
SCR Package TO-64 Case style, Bolt Mount Package
TO-64 SCR, Stud-Mount Component Package
The TO-64 package is a 3-terminal Bolt mounted device used for high power Silicon Controlled Rectifier [SCR] components. Of course other 3-terminal semiconductors may also use this case style, but the SCR is shown as the example.
As of 1996 JEDEC considers the TO-64 case outline inactive for usage and has removed the case designation. Components manufactured after 1996 may not be found using the designation.
The Anode or bolt side of the component body should be attached to a Printed Wiring Board [PWB] or metal heat sink while the opposite terminals of the component [Cathode and Gate] require lead wires to attach to the circuit. The lead wires selected should be the largest diameter wire that will still pass through the tab cut-outs.
The Anode of the package should be mounted to a heat sink if possible, as in a larger copper pad on the PWB or metal plate used to dissipate heat. The lead wires attached to either the Gate or Cathode will not be able to dissipate any heat from the package, because of the length and resulting thermal resistance of the wire. The stud, or anode in this case, is normally a 10-32 threaded bolt.
