Board level reliability of the advanced RF power packaging

As the market demand of high power, high frequency and high efficiency, the advanced RF power packaging and assembly technology is facing the challenge of new material and new design. Improving the thermal conductivity of the heatsink (flange) is one of the effective ways to obtain low thermal resistance (Rth) component. Compared to the silicon transistors, the low-cost, high thermal conductivity material exhibits lower structural stiffness than the flange material which is widely used. A good understanding of the potential failure mechanism in board level reliability is an essential for a robust packaging development. This paper will focus on the board level reliability and modeling technique for bolt down assembly process. A modified three-point bending (3ptB) test method is also used to charcterised the structural stiffness of the packaging. Hence, the model is able to predict the ringframe crack of the particular package design which is under the board level thermal cycling test. Afterwards, impact of the flatness of the application board, flatness of the flange and the pitch of the mounting screws will be described.