Technical Paper: PIM International, Vol.1 No. 4 December 2007, pages 56-59, 2294 words

Authors: Zhang Chi, Xu Bo and Wu Ziguang

School of Material Science & Engineering, Chongqing Institute of Technology, No .4 Xingsheng Road, Yangjiaping, Chongqing 400050, P.R. China

Abstract

The process of metal injection moulding (MIM) for a semiconductor housing is analysed in this paper. With an introduction of a new type of binder system for processing Fe-Ni alloy based housing parts using MIM process, the efficiency of the debinding process is greatly improved. In addition, the sintering process is stabilised. As such, not only can we achieve zero defects, but we can also provide the industry with environmental protection in processing ‘green’ parts. Process optimisation and SPC (Statistic Process Control) technology is applied in controlling the weight of ‘green’ parts. After sintering, it is shown that linear dimensional tolerances of ±0.2% of the housing component have been achieved, furthermore the mechanical properties and precision can also meet all required properties of the final product.

Introduction

Metal injection moulding (MIM) is a relatively new type of net shape technology in manufacturing. It has been generally applied to produce geometrically complex metal parts. To date, injection moulding is widely recognised as a manufacturing process approach that can form complicated shapes with plastic materials. More and more interest has been focused on MIM not only because of main five main key features: low production costs; shape complexity; tight tolerances; applicability to several materials; and high mechanical properties but also this technology has undergone commercialisation widely since 1980’s. Today, it is commonly used in electronics, automobiles, the semiconductor industry, ornaments, medical instruments and so on [1][3].

As shown in Fig.1, this housing part for the semiconductor industry is made of Fe-Ni alloy (Fe54%,Ni46%). It has complex details. The wall thickness is 1.5mm and overall dimensions are (85.1× 85.1 × 8.5)mm. There are two open slots (undercut) with high precision requirements at the sidewall. The length is (15.11±0.02)mm; height (1.63±0.02)mm. Due to the complexity in shape as well as economic concerns, it is difficult to machine using traditional manufacturing processes. Hence, MIM technology is the right way to process this complex housing part so as to meet engineering requirements at the lowest cost ......

Further sections of this article include:

- Experimental part
- Conclusions

Figures and Tables:

Fig. 1 The housing part formed from Fe-Ni alloy by MIM

Fig. 2 Process flow chart for MIM

Fig. 3 The injection mould of the housing ‘green part’

Fig. 4 The fishbone diagram outlining the major defect categories and individual members of each category

Fig. 5 SPC control chart for housing ‘green part’ weight

Fig. 6 Depolymerising control chart

Fig. 7 Sintering control chart

Fig. 8 The microstructure of sintered housing.

Table 1 The binder system developed for MIM of housing part