Why Palladium Cobalt Makes A Difference
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Characteristics
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Why This is Good For a Test Probe
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Specifications
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PdCo is very hard
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A hard surface finish decreases wear and increases durability
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Hard Gold hardness: Knoop 130-200
PdCo hardness: Knoop 600-650
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PdCo is slippery
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A low coefficient of friction makes the plunger motion smoother and makes it easier for foreign matter to slide off the surface of the plunger
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Hard Gold coefficient of friction: .60
PdCo efficient of friction: .43
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PdCo has a small grain size
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It is less likely that a small grain size material will allow diffusion and the formation of intermetallic compounds
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Hard Au grain size: 200-250 Angstroms
PdCo grain size: 50-150 Angstroms
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PdCo has low porosity
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Low porosity does not allow corrosion to penetrate the plating and damage the base metal
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Hard Gold porosity index: 3.7
PdCo porosity index: 0.2
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PdCo has good ductility
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A ductile plated surface is less likely to crack under mechanical stresses
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Hard Gold: <3% elongation
PdCo: 3-7% elongation
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PdCo is thermally stable
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When exposed to elevated temperatures over time, the contact resistance stays consistent
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Hard Gold: up to 150 Degrees C
PdCo: up to 395 Degrees C
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Pd and Co have high melting points
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A plating material with a high melting point will inhibit diffusion and the formation of intermetallic compounds
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Gold melting point: 1,064 Degrees C
Palladium melting point: 1,554 Degrees C
Cobalt melting point: 1,495 Degrees C
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PdCo is an alloy
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Alloys are good barriers to diffusion
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Hard Gold chemistry: almost 100% Au
PdCo chemistry: 80% Pd / 25% Co
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PdCo has surface oxides
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Surface oxides help deter solder adherence
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Palladium does not oxidize until 380 Degrees C and cobalt oxides are thin, self limiting and conductive
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