Research On Diamond/Al For IGBT Base Plate In Composite Pressure Casting Method

As an important switch components with high power——IGBT module, thethermal stress caused by frequent thermal cycling results the welding layer (brazingfiller metal) cracking, which make IGBT chip fails because of module’s hightemperature when it works to produce heat. Compared with the traditional electronicpackaging materials, Diamond/Al can fully solve the IGBT module’s main failureproblem, for which has high thermal conductivity and has the thermal expansioncoefficient matched to IGBT encapsulation material,such as Si、Ga、As and it also hasthe advantages of high stiffness, low density and high geometric accuracy. Thesequalities are good performance owned by packaging materials which has broadprospects.In this issue, Diamond/Al basalia is produced by squeeze casting with net shapeforming technology: As we know, the wettability between diamond particles andaluminum liquid is not good; So Diamond carbide particle is pretreated with surfacemetalization is to improve the character, to prevent harmful interface reactiondiamond interface with aluminum, and to improve the adhesion between diamondparticles and aluminum interface. Molten aluminum named ZL104stays at740±5℃for30min, the mold’s temperature preheats at540±5℃.This paper shows adopting the squeeze casting with net shape formingtechnology to manufacture the composite material——Diamond/Al, firstly fill theDiamond powder consisting of a certain proportion of different fineness into themould on the platform vibrator. The size ratio of diamond particles, is determined bythe theoretical formula and experimental analysis method; particle matching for theideal should be accounted for70%of60#diamond particles, accounting for30%of320#diamond particles; then compact Diamond powder, last cast Al liquid to moldthe product by a new method of pressure infiltration casting. Corresponding concavemachined by CNC inside the mould, and with0.1~0.2mm thick Al2O3paper added inthe diamond particleson both sides, the Al2O3paper is burned into Al foils attached toDiamond/Al basalia under high temperature and high pressure. When the volumefraction of Diamond reached58%～62%, the effect of molding Diamond/Al increaseswith the die preheating temperature, in the case of liquid Al’s better penetration effect.The Diamond particle size makes direct impact on the quality of Diamond/Al. Mainlyit impacts molten aluminum’s infiltrability into Diamond particles.Otherwise, the optimal preheating temperature of mould and Aluminum’s meltedtemperature are mainly determined by Ansys thermal analysis, it benefits aluminumliquid permeability,grain boundary binding, increases substrate hardness and reducesthe sample porosity; Mechanical stress analysis by Ansys verifys to optimizethickness of the outer die sleeve wall and reinforcement of ribs. Diamond/Al basaliaproduced by composite squeeze casting, through the instrument to test its thermalconductivity and thermal expansion coefficient, test values are in line with therequirements of properties of cmposite material; including aluminum foils process, arch surface realization and the density of the composites are in line with the basicrequirements of finished products. Diamond/Al-the composite material to IGBTmodule with the superior performance is adopted into electronic packaging, and willbe expected to become a new generation of electronic packaging materials.