As electronics and semiconductor devices continue to demand smaller size, lower weight, and higher power, heat-flux density keeps increasing. If that heat cannot be removed in time, both stability and long-term reliability suffer. That is why thermal management remains a central issue in advanced electronic systems.

Diamond-reinforced metal-matrix composites are attractive because they combine high thermal conductivity, low density, and a coefficient of thermal expansion that can be tuned for package compatibility. Their final performance, however, depends on several interacting factors, especially interface design, process parameters, and fabrication route.

In these materials, diamond acts as the reinforcement phase and provides the main thermal advantage. As more diamond is introduced, particles begin to contact one another and build a continuous heat-conduction network. In many cases, a mixed particle-size distribution performs better than a single-size system because it packs more efficiently and extends the thermal pathway.

Interface modification

The two main routes are matrix alloying and metallization of the diamond surface. Metallization can be divided into two broad approaches:

1. Coating the diamond surface with a non-carbide-forming element such as Cu.

2. Coating the surface with a carbide-forming element such as Ti, Cr, or W, followed by annealing or another high-temperature treatment that activates interfacial reaction.

Common metallization routes include electroless plating, magnetron sputtering, vacuum evaporation, and salt-bath processing.

Matrix alloying introduces suitable active elements into the metal before fabrication. This improves wetting, promotes carbide formation, strengthens interfacial bonding, and raises thermal conductivity. Without modification, fracture surfaces often show smooth diamond particles with weak adhesion. After modification, bonding improves markedly and the interface becomes more reliable.

Process parameters

Even with good interface design, process parameters still matter. Temperature, pressure, holding time, and heat treatment all influence densification, interface reactions, porosity, and the final thermal conductivity of the composite.

Holding time

A suitable holding time allows sufficient reaction at the interface and helps form a stable carbide layer. If the time is too short, diffusion remains incomplete; if it is too long, excessive carbide growth can create stress concentration and damage the matrix.

Sintering temperature

Temperature directly affects diffusion and reaction degree. In general, an appropriate increase in temperature reduces porosity, improves bonding, and supports both higher mechanical strength and better thermal conductivity.

Pressure

Pressure increases the contact area and contact force between particles. It helps suppress graphitization under harsh conditions and supports a denser, more stable interface.

Heat treatment

Proper heat treatment strengthens bonding between diamond particles and the matrix, promotes interdiffusion, forms beneficial interfacial compounds, and improves structural stability, toughness, and wear resistance.