Hermetic Sealing a Ferrule & Fiber Optic Cable

Objective

To heat a Kovar ferrule and fiber optic cable to 297°F within 10 seconds for a soldering application, to form a hermetic seal

End Product

fiber optic cable

Equipment

Ambrell 1kW power supply with a specially designed induction coil

Materials

Gold-coated cable, Kovar ferrule, solder and flux

Temperature

297 ºF

Frequency

360 kHz

Testing

A specially designed, 4-turn “C” shape coil was used to provide uniform heat to the assembly near the joint area. With this design, the coil can be lowered directly onto the joint; it  s not necessary to feed the ferrule assembly through the coil. Flux was applied to the assembly where the ferrule and fiber optic cable were to be joined. RF power was applied for 10 seconds, which caused the solder to melt and flow.

Benefits

Consistent and repeatable results were achieved with the Ameritherm 1 kW power supply and a 10-second heat cycle. The solder flowed evenly and bonded the fiber optic cable to the Kovar ferrule. With the induction coil’s compact design, a very small surface area was heated with pinpoint accuracy.

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