Induction sealing glass to encloseĀ resistors with high frequency induction heating system
Objective Provide a hermetic seal of glass enclosed resistor to a lead
Material ResistorĀ Kovar rings, 0.1 inch (0.254cm) diameterĀ Glass tube slightly larger than 0.1 inch (0.254cm) diameter,Ā 0.5 (1.27) inch length
Metal lead
Temperature 900 ĀŗF (482) ĀŗC
Frequency 324 kHz
Equipment ā¢ DW-UHF-6kW-III induction heating system, equipped with aĀ remote workhead containing two (2) 1.5 Ī¼F capacitors (forĀ a total of 0.75 Ī¼F).
ā¢ An induction heating coil designed and developedĀ specifically for this application.
Process A three turn concentrator plate coil is used to heat the KovarĀ ring for 500 milliseconds. This causes the glass to melt andĀ seal one side of the resistor. The resistor is then turned over
and the process is repeated to seal the other side using aĀ second Kovar ring.
Results/Benefits Induction heating provides precise, consistent heat to veryĀ small parts resulting in repeatable, quality seals.
By heating with medium frequency, arcing (which occurs atĀ high frequencies) is avoided.