Intermetallic phase formation in diffusion-bonded Cu/Al laminates prepared by plasma activated sintering (PAS) was investigated in the temperature range 673–773 K for 10–30 min. Three intermetallic phases, Al4Cu9, AlCu, and Al2Cu, were identified in all the samples. The formation of Al2Cu as the first phase was rationalized on the basis of the effective heat of formation (EHF) model. The thermodynamic driving force for the preferential appearance of Al4Cu9 at the α-Cu(Al)/Al2Cu interface was evaluated. The time and temperature dependences of the growth of the three intermetallic layers were determined, and their apparent activation energies were calculated. The growth kinetic of the layers conformed to the parabolic law, implying that the intermetallic phase formation was volume diffusion-controlled in the temperature range. The apparent activation energies calculated for the growth of the total intermetallic layer, Al4Cu9, AlCu, and Al2Cu layers were about 80.8, 89.8, 84.6, and 71.1 kJ/mol, respectively.

Intermetallic phase formation in diffusion-bonded Cu/Al laminates

Automatic wire bonding is a highly mature, cost-efficient and broadly available back-endprocess, intended to create electrical interconnections in semiconductor chip packaging. Modern production wi ...

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Unconventional applications of wire bonding create opportunities for microsystem integration

Heat treatments performed on copper-clad aluminium thin wires increase the ductility of copper and aluminium but activate diffusion between both layers, creating brittle intermetallic compounds. Ductility reaches a maximum for an optimal intermetallic thickness related to appropriate annealing conditions in order to avoid Kirkendall void formation assisted by stress gradients.

Brittleness study of intermetallic (Cu, Al) layers in copper-clad aluminium thin wires

A brief review of selected aspects of the materials science of ball bonding

Overview of wire bonding using copper wire or insulated wire

https://uwaterloo.ca/centre-advanced-materials-joining/sites/ca.centre-advanced-materials-joining/files/uploads/files/hang_growth_behaviour.pdf

H.H. Wang

Papers

Growth behavior of Cu/Al intermetallic compounds and cracks in copper ball bonds during isothermal aging.