General Electric SSL-140 LED Display | |
Written by AnubisTTP on 2011-04-27 |
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One of General Electric's most well-known displays, the SSL-140 is an early seven-segment LED in a tiny surface mount package. The SSL-140 is a single die device, in that all of the segments are constructed on the same lump of silicon. The display's decimal point is a separate small cubical die located in the right side of the display area. The segments on the SSL-140's single die extend almost to the edge of the semiconductor area, a construction style common to early LED's that lowered yields and that manufacturers quickly abandoned. The SSL-140's dies are bonded to a ceramic wafer with gold leads, with an enclosing plastic cover to protect the fragile dies and bond wires.
The home experimenter should be cautioned that the SSL-140 is a frail device. The bond between the leads and the ceramic wafer is not strong, and careless handling can easily dislodge the leads and break the bond wires. Collectors should exercise care when handling this LED, especially with loose examples that have been removed from their protective cardboard sleeve.
![General Electric SSL-140 LED Display](media2/pict26/ssl140x1.jpg)
General Electric SSL-140 LED display, normal operation.
![General Electric SSL140 LED Display](media2/pict26/ssl140x2.jpg)
The SSL-140 is very small, and was likely targeted towards the then-nascent pocket calculator industry.
![General Electric SSL-140 Diode Die](media2/pict26/ssl140x4.jpg)
This damaged SSL140 has had it's cover removed so the die can be seen. The segments on the SSL-140 reach almost all the way to the edge of the die, a construction style that was quickly abandoned in later LEDs.
![General Electric SSL140 Light Emitting Diode](media2/pict26/ssl140x3.jpg)
SSL-140 LED display, shown with packaging and quarter for scale.
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