# A Numerical Study on Optimization of Shape and Dimensions for Cold-Extruded Blank of Copper Pin-Type Heat Dissipation Substrates

## TL;DR

This study optimizes the shape and dimensions of copper pin-type heat sink substrates to improve material usage and reduce forming loads during cold extrusion.

## Contribution

The novel contribution is the numerical investigation and optimization of stepped blank shapes and orientations to enhance cold extrusion performance.

## Key findings

- The stepped blank with front orientation provides the best forming performance with the lowest load and sufficient pin-fin filling.
- Dimension optimization reduced the forming load by 35.3% while meeting design requirements for thickness and pin-fin height.
- Experiments confirmed the feasibility of the optimized stepped blank configuration for mass production.

## Abstract

The thermal dissipation performance of the radiator is crucial for the stable operation of power electronic devices. Due to excellent thermal performance, copper pin-type heat sink substrates are widely adopted. However, the cold extrusion process for heat sink substrates suffers from low material utilization and high forming loads. To improve material utilization and reduce cold extrusion forming load, four blank shapes (rectangular, trapezoidal, trapezoidal cap, and stepped) were designed using finite-element simulation to investigate the effects of blank shape and placement method with orientation relative to the die cavity on forming quality. Further dimensional optimization was conducted to determine the optimal configuration. The results show that the stepped blank with front orientation exhibits the optimal forming performance, featuring the lowest forming load and the most sufficient pin-fin filling. Compared with back orientation, front orientation achieves higher and more uniform material flow velocity, and significantly reduces forming load. Through dimension optimization, the 7 mm-thick stepped blank is determined as the optimal solution, with the forming load reduced to 15,000 kN (a 35.3% decrease compared to the initial 7.5 mm stepped blank), and both the substrate thickness and pin-fin height meet the design requirements (4.5 mm and 6.5 mm). Experiments verify the feasibility of the optimized scheme, providing technical support for the low-cost, high-quality mass production of copper pin-type heat sink substrates.