Non-Arc Welding Processes

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Non-Arc Welding Processes
Introduction

• Resistive heating, chemical reactions, focused
  light and electrons, sound waves, and friction
  can also be used to join materials
• Resistance welding
• Oxy-Fuel Welding
• Friction welding (Solid State)
• Laser and electron beam welding
• Brazing and soldering
• Plastics joining
• Adhesive bonding

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Brazing (B) and Soldering (S)

• In these processes, the base metals are heated
  but do not melt only the filler metal melts
• Brazing filler metals having a melting point
  above 840 F (450C)
• Soldering filler metals have a melting point
  below 840F (450C)

Brazing and Soldering
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Brazing and Soldering
0.1.1.2.4.T18.95.12
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Application of Low Thermal Expansion Alloys

• Thermal expansion mismatch in metal-ceramic
  joints can lead to cracks in the ceramic
• Thermal expansion coefficients at 25C (10-6 mm /
  mmC)
• Alumina, 8.8
• Nickel, 13.3
• Iron, 11.8
• Kovar, 5.0

Kovar lid
Silicon chip
Alumina substrate
Brazed joints
0.1.1.2.4.T20.95.12
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Brazing Specifications
Brazing and Soldering

• AWS A5.8 Specification for Brazing Filler Metal
• 8 well-defined groups (B) plus a vacuum grade
  (BV)
• BAg-1 (44-46 Ag, 14-16 Cu, 14-18 Zn, 23-25 Cd)
• BAu-1 (37-38 Au, remainder Cu)
• BCuP-1 (4.8-5.2 P, remainder Cu)
• Standard forms strip, sheet, wire, rod, powder
• Joint design tolerances, generally 0.002 -
  0.006 inches
• Uses for each braze material
• AWS C3.3 Standard Method for Evaluating the
  Strength of Brazed Joints

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Balchin Castner, Health Safety, McGraw
Hill, 1993
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Advantages
Brazing and Soldering

• Joins unweldable materials
• Base metals dont melt
• Can be used on metals and ceramics
• Joined parts can be taken apart at a later time
• Batch furnace can easily process multiple parts
• Portable when joining small parts

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Limitations
Brazing and Soldering

• Joint tolerance is critical
• Lower strength than a welded joint
• Large parts require large furnaces
• Manual processes require skilled workers
• Flux