Technical Paper: PIM International, Vol.1 No. 1 March 2007, pages 53-58, 3103 words

Author: Velda Josef and Lye-King Tan

Advanced Materials Technologies Pte Ltd, 3 Tuas Lane, Singapore 638612

Abstract

As processors are getting faster and hotter, heat dissipation becomes an important thermal issue to be considered. In recent years, there are many new developments in thermal management devices in order to overcome the thermal barrier. The design started from common thermal management device of passive heat sinks with mounted fan to heat pipe and now the solvent transportation. The conventional manufacturing processes for most heat sinks are extrusion, forging, machining and die-casting. However, Metal Injection Moulding (MIM) is gaining recognition lately as a good and economical means to fabricate intricate heat sinks for more sophisticated thermal design system. This paper highlights the thermal performance of MIM heat sink compared with other conventional process.

Introduction

The rising demand of higher performance but more compact electronic devices has created the need to make microprocessor chips faster and smaller. Alongside with this development, heat dissipation becomes a thermal barrier to the performance of the chip and also believed to shorten the life expectancy of the device. An efficient thermal management device has become a crucial part to a microprocessor. The device started off with passive heat sink, with fins to radiate heat into the heat transfer medium, air being most common. Active designs involves circulating heat transfer medium, by pumps or fans.

There are several conventional fabrication methods for heat sinks: extrusion, die-casting, cold forging, and machining. Machining offers freedom to heat sink designer, but the cost can be high for complex design. MIM, however, is gaining recognition lately as a good and economical means to fabricate intricate heat sinks for more sophisticated thermal system designs. The process has characteristics that are potentially advantageous to heat sink fabrication, for example complex shape capability, giving designer more flexibility in design concept with minimum cost impact.

Aluminum and copper are the two most common heat sink materials, owing to their lightweight and high thermal conductivity properties. The fabrication of a superior aluminum heat sink using MIM process known as aluMIM™ has been done over the last couple of years [1].

This paper presents the comparison of two heat sink fabrication methods, namely copper MIM, or cuMIM™, and machining, in terms of their thermal performances.......

Further sections of this article include:

- Heat sink performance
- Experimental procedure
- Results and discussion
- Conclusion

Figures and Tables:

Fig. 1 Scanning electron micrograph of copper Powder

Fig. 2 Green part MIM heat sink

Fig. 3 Sintered MIM heat sink (left) with green part (right)

Fig. 4 MIM round pin (left) and MIM square pin (right)

Fig. 5 Setup of Thermal Resistance Measurement

Fig. 6 Comparison of Thermal Resistances

Table 1 Copper powder specification

Table 2 Comparison of thermal properties of C11000 copper and cuMIM™

Table 3 Thermal Performance Summary for C11000 Square Pin Heat Sink

Table 4 Thermal Performance Summary for MIM Square Pin Heat Sink

Table 5 Thermal Performance Summary of MIM Round Pin Heat Sink