The Study Of Fabrication And Properties Of SiCp/Al Electronic Packaging Materials

In this paper SiCp/Al composites were fabricated for the purpose of producing electronic packaging material.Powder injection molding(PIM),selective laser sintering(SLS) were used to fabricate complex-shaped SiC preforms with volume fraction of 64%and 32%respectively and key technology was investigated.SiCp/Al composites were fabricated by vacuum pressure infiltration and properties of composites were studied.Finally,electroless plating on the surface of SiCp/Al composites was investigated in order to improve its surface characteristics and the properties of cladding were assessed.SiC preforms were fabricated by PIM technology.A binder system of PIM was developed and a new technology which is solvent debinding+infiltrating high-temperature-binder+ thermal-debinding was developed.The debinding process of green parts was investigated.In the process of solvent debinding,key factors such as temperature,time and thickness of green parts were discussed,it is found that the removing-rate of binder was controlled by diffusion.Finally, SiC performs with adjustable flexural strength were fabricated and can meet the requirement of different infiltration technologies.Complex-shaped SiC preforms were fabricated by SLS technology,the parameters were optimized and the key factors such as pre-temperature,thickness of slice-layer and scanning interval was discussed.Meanwhile,the effect of power density,scanning interval and scanning rate on the sintering-depth was investigated.SiCp/Al composites with good interface were produced by vacuum pressure infiltration. The effect of SiCp size on SiCp/Al composites was investigated.The results show that when temperature is lower than 200℃the SiCp size has little effect on composites,and when temperature increases the SiCp/Al composites reinforced by small size SiCp has lower CTE. Meanwhile,the SiCp/Al composites reinforced by small size SiCp has higher flexural strength but lower hermeticity.The CTE curve of casting composites was investigated;it shows that in different temperature range the behavior of thermal expansion was controlled by different factors.The residual stress has important effect on the thermal expansion behavior of composites and the residual stress of composites can be reduced by thermal cycles.As a result the thermal properties such as CTE and thermal conductivity of composites were improved evidently.Effect of heat treatment on the dimension stability of SiCp/Al composites was investigated and the influence factors were analyzed.The results show that annealing and solution-aging can improve the dimension stability of composites,while quenching has an opposite.Electroless Ni(Co)-P plating process on the surface of SiCp/Al composites was investigated in order to improve its surface characteristics.Palladium activation method,nickel activation method and two steps infiltrated zinc method were adopted to active the surface of composites.Palladium activation method with Pt atoms distributed on the surface,the methodology was brief,but the costing was high;nickel activation method costs low,some factors such as activation time,heat treatment and content of nickel have great effect on the activation results,the experiment results show that the cladding has good properties with 10min activation time,heat treatment process 180℃×25 min and nickel concentration over 50g/L. Two-steps-infiltrated zinc method was adopted,when zinc solvent contains some nickel ion and pre-plating in alkali zinc solvent then in the acid zinc solvent the cladding has excellent adhesion property,and phosphorus content was 8～10wt%.The cladding abtained by above methods has good adhesion property when exposed at 400℃for 20 min or 450℃for 2 min.