Properties and microstructural results of short carbon fibre reinforced Cu-matrix composites made by electroless copper coating

Beschreibung

Carbon fibre reinforced copper matrix composites possess properties of copper, i.e., excellent thermal and electrical conductivities, but the properties of carbon fibre, i.e., a small thermal expansion coefficient are dominating the mechanical behaviour. Since the desireble porperties of the composite can be obtained by selecting the amount and type of the carbon fibres, it is considered to be suitable for use as electric and electronic materials like special heat sinks as a competition in order to overcome some disadvantages of e.g. Copper-Molybdenum, Copper-Invar of Aluminium-Silicon Carbide. Copper matrix composites with high conducting endless carbon fibres have been investigated since several years in different research groups, but copper matrix composites with high conducting short fibres are a new and promising field of research. Short carbon fibre reinforced copper composites have been made by hot-pressing of copper coated carbon fibres chopped into different lengths (100 µm - 2 mm). Due to a special production route - electroless copper coating - a good distribution of the fibres in the matrix and a good interfacial contact is given. The fibre length distribution influences strongly the properties of the composite. During hot pressing, the carbon fibres take on a preferred orientation in a plane perpendicular to the hot pressing direction. Within this plane the fibre orientation is random. Samples using PITCH- and PAN-type fibres have been produced. The volume content of carbon fibres hs been varied in a range of 30-65 vol%. The microstructure of the composites has been investigated using SEM and optical microscope. Measured porperties, i.e., thermal conductivity and coefficient of thermal expansion have been compared with microstructural results and results obtained from mathematical models. Up to now these composites provide thermal conductivity of about 250-300 W/mK in two dimensions and about 140 W/mK in the third dimension. The coefficient of thermal expansion (CTE) can be tailored in a range of 4-10 ppm/K by changing the content of carbon fibres. The relatively low density of about 4-6 g/cm3 is also of importance wherever weight reduction is desired. The paper is a corresponding publication to the paper: "Thermal expansion and thermal conductivity of endless carbon fibre rienforced copper matrix composites" at the same conference.

Zeitraum	27 Apr. 1998 → 29 Apr. 1998
Ereignistitel	Electronic Manufacturing Technology Symposium - IEMT Europe´98
Veranstaltungstyp	Sonstiges
Bekanntheitsgrad	International