Fast fabrication of high thermal conductivity copper-diamond composites via DC electrodeposition with simple electrolyte formula

Background

High heat flux probably causes serious reliability issues in power device packaging due to the low thermal performance and thermal mismatch of traditional packaging materials. Copper-diamond composite material has high thermal conductivity (TC) and low thermal stress but still faces shortcomings in preparation efficiency, heterogeneous interface quality, and dissatisfactory TC using existing electrodeposition technology.

Methods

A novel electrolyte with a simple formulation appropriate for high-rate defect-free copper-diamond composite electrodeposition was proposed. The properties of the electrolyte were evaluated by electrochemical measurements and contact angle tests, the electrodeposition process parameters were systematically optimized, and the quality and thermal characteristics of the composite coating were elaborately appraised.

Significant Findings

The electrolyte could withstand high current density and presented excellent wettability with diamond particles. Through optimizing the current density to 4 A/dm² (ASD), the copper-diamond composite was fast fabricated at an average rate of over 90 μm/h, along with a smooth, uniform, and bright grain refined (18.6 nm) copper matrix. High concentration diamond particles were evenly distributed in the copper matrix without defects at the copper-diamond heterogeneous interface. These improvements jointly promote the efficient preparation of copper-diamond composites with high TC (638 W/(m·K)) and low CTE (9.94 × 10^–6 / °C), thereby expediting the thermal performance and reliability of high heat flux device packaging substrate while boosting effectiveness.