Introduction
Non-Arc Welding Processes
• 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
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
(450°C)
– Soldering filler metals
have a melting point
below 840°F (450°C)
Brazing and Soldering
Brazing and Soldering
0.1.1.2.4.T18.95.12
Application of Low Thermal
Expansion Alloys
• Thermal expansion
mismatch in metalceramic joints can
lead to cracks in the
ceramic
• Thermal expansion
coefficients at 25°C
(10-6 mm / mm·°C)
–
–
–
–
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
Brazing and Soldering
Brazing Specifications
• AWS A5.8 Specification for Brazing Filler Metal
– 8 well-defined groups (B) plus a vacuum grade (BV)
• BAg-1
• BAu-1
• BCuP-1
(44-46 Ag, 14-16 Cu, 14-18 Zn, 23-25 Cd)
(37-38 Au, remainder Cu)
(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
Balchin & Castner, “Health & Safety…”,
McGraw Hill, 1993
Advantages
Brazing and Soldering
• Joins unweldable
materials
– Base metals don’t 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
Brazing and Soldering
Limitations
• Joint tolerance is
critical
• Lower strength than a
welded joint
• Large parts require
large furnaces
• Manual processes
require skilled
workers
• Flux
Filler metal ring
surrounded by flux