Feasibility study of thermally integrated mechanical configuration for a novel 3-D flex MCM

As electronic applications become more demanding, the need for increased packing density and speed increases. Simultaneously, the demands for miniaturization also increase. With the concept of 3D MCM packaging, these requirements can be achieved in a smaller and more efficient package. Although there have been several excellent attempts at producing the 3D MCM, the factors needing adequate consideration include cost reduction and durability. Flexible films, when used as substrates, offer exciting advantages that include enhanced packaging density by including embedded passives as well as an important flex-layer to flex-layer rework capability. Mechanically, the objective then becomes one of integrating the electrical and thermal objectives together with desired reliability. The thermally integrated mechanical configuration that is reported in this paper is unique due to its high level heat dissipation capabilities as well as the insulating and mechanically flexible properties of the polymer based substrate film. The paper reports on the reliability of the mechanical configuration with z-axis signal transmission realized by an SMT connector. These factors decide the form and the reliability of the mechanical structure. Air, liquid and heat pipe cooling are possible alternatives for the cooling structure. Although the final application is likely to alter the specific mechanical structure, the purpose of this paper is to demonstrate that a 3D MCM with flexible films is feasible and mechanically reliable