Research On Preparation Of Multilayer Of SiC/Al Electronic Packaging Part By Using Semi-solid Die Forging And Bonding Integration

With the rapid development of integrated circuit technology,the demand for electronic encapsulation materials with high-performances is increasingly urgent,leading the change of the electronic packaging technology towards a more reliable,higher performance and lower cost direction.As one of ideal materials for electronic packaging components,SiC/Al composite materials with high volume fraction show comprehensive performances,with low density,high heat conductivity and low thermal expansion coefficient like aluminum and high strength like SiC.However,it has always been difficult issues about the preparation and connection of SiC/Al composite materials.The thermal physical properties and mechanical performances of the forming parts are easily influenced with different processes and different parameters.Wetting behavior and interface reaction between SiC and Aluminum are the important factors affecting the mechanical and physical properties of SiC/Al composite materials.In this paper,SiC/Al composite materials with different volume fraction of reinforcement phases were fabricated by hot pressing method,changing the volume fraction and granularity of SiC particles.With adding different contents of magnesium and silicon to change the matrix composition,the influences of alloy components on composite material properties were studied.By bending strength tests,thermal conductivity tests,thermal expansion coefficient tests and density tests,the change rule of thermal and mechanical properties of composite materials with different components and different volume fractions of SiC were researched.The microstructures,phases and interface morphology were observed by using SEM,XRD and TEM.The results show that the bending strength improved with the increase of volume fraction of SiC.But when volume fraction is more than 50%,brittleness of composite materials increase quickly.Both of thermal conductivity and coefficient of thermal expansion decrease with the increasing of SiC volume fraction.So the volume fraction of SiC should reach at least 60% to meet the requirements that the thermal expansion between electronic packaging and chips inside could match with each other.When the volume fraction of SiC remains the same and SiC particles and matrix particles show similar size,the bending strength,thermal conductivity and density of the composite achieve the best level.The addition of magnesium in the process has no apparent influence on performance of the composite materials that only increasing density slightly,on the contrary,reducing the bending strength and thermal conductivity.The addition of silicon further reduces the thermal expansion coefficient and increases bending strength.When the silicon content reaches 6%,the composite materials show the best performances.Adding 6% magnesium and 6% silicon respectively,the hot pressing parts with different volume fraction of SiC were connected by die forging.It was found that double-level connection parts with low volume fraction of SiC show higher shear strength,more compact microstructure,without crack defects.However,the double-level connection parts with high volume fraction of SiC show lower shear strength,with obvious gaps on the connection interface.By adding the middle layer can improve the shear strength of the interface and avoid the generation of cracks.B y transmission and diffraction analysis on the interface of SiC and Al uminum,a relationship between the two phase crystal-orientation on the interface is found.There is a transition layer of certain thickness on the interface without the certain relationship,and there are interface compounds on certain parts of the interface.Finally,five composite materials with different volume fraction from 10% to 60% were selected,and the electronic packaging parts with different volume fraction of SiC particles in gradient distribution were fabricated with best comprehensive performances.