Electronics - Relay Welding
Relays used in aerospace and defense applications or where ultra-high reliability is needed in a demanding or explosive environment call for hermetic packaging. Because these units employ a mechanical contact connection they can be fouled by foreign debris and create sparks which could create an explosion hazard if not fully isolated. These units use glass-to-metal seals as feed-throughs that are very close to the seam between the case and header. Too much heat and the glass will crack, creating scrap.
Lasers easily perform the seam welding and spot welding tasks needed to assemble and seal these devices. Spot welds will assemble the relay contacts inside the unit and seam welds will hermetically seal the header onto the can with the glass-to-metal seals within less than 1mm of the weld.
Stainless steels are typically used for the can material but some other iron alloys can be used depending upon their magnetic properties. The header material is often a cupro-nickel or Kovar material to match the glass-to-metal seals. The relay contact components can vary a great deal based on their electronic and wear properties. Weld penetrations tend to be low, on the order of 100um-250um to minimize heat input and distortion.
Pulsed YAG lasers produce the necessary pulse energy and discrete pulses for spot welding relay components. The same laser produces the seam weld around the header. For small packages a galvo mirror system can be used to move the beam around the part.
Typical lasers that have been used for this application
JK125P, JK300P & JK300HP
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