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MOTOROLA INC. Technical Developments Volume 13 July 1991
SURFACE MOUNT LAMP TERMINATION ATTACHMENT PROCESS
by Evencio Fernandez, Yung Chuang and Russ Strobe1
ABSTRACT
A simplified process for attaching terminations to a fused lamp for surface mounted reflow application is described. With the use of flexible conductive epoxy and closed end termination end-caps, the current attachment process steps can be drastically reduced while improving overall component quality and factory defects.
DESCRIPTION
The growing popularity for liquid crystal display in electronic products has significantly increased the market demand for back lighting of the product's display area. Miniature fused incandescent lamps is one of the most popular methods for illuminating the display screen. These lamps have traditionally been supplied with wire leads extending through the fused ends of the lamp and have been hand soldered to the printed circuit board. Recently, surface mounted and reflowable lamps have become available. They have improved factory throughput and simplified the prod- uct assembly process.
The current end-cap termination attachment is accomplished by using an open end metal sleeve, feeding the wire termination through the sleeve, soldering the wire to the outside of the sleeve and t
backfilling the sleeve/lamp interface with RTV silicon (see Figure 1). There are a total of six process steps involved in this kind of construction as depicted in Figure 2. Since the sleeve is open at both ends, a gross and a fine silicon application is necessary to prevent the silicon from spilling out of the sleeve. Even wit...
