Reliability Of Vertical Interconnection Of Microwave Module Based On LTCC

In the demand of high function density and miniaturization of microwave module,three-dimensional microwave multi-chip module is an effective and feasible solution.The reliability of vertical interconnection is the main restriction of this technology,of which the research at home and abroad pay much attention to the signal connection and little attention to mechanical connection.In this paper,the reliability of the vertical interconnection of microwave modules composed of low temperature co-fired ceramic(LTCC)from two aspects: the mechanical reliability of the copper through-vias inside the substrate and the ball grid array solder joints between the substrates.For the vertical interconnection inside the substrate,an analytical model of the axisymmetric plane problem based on polar coordinates and a two-dimensional numerical simulation model are established to study its reliability during operating process.The effects of temperature,through-via interaction,through-via diameter,and through-via spacing on hoop stress and radial stress are comparatively analyzed.Different optimization schemes are proposed for the failure of LTCC and copper through-vias.For the vertical interconnection between substrates,based on the orthogonal test method,four factors including solder ball material,solder paste thickness,solder joint arrangement,and substrate thickness are designed to study the reliability during manufacturing and operating process.In terms of the reliability during the manufacturing process,a three-dimensional numerical simulation model based on the birth and death element method is established,and the residual stress of the solder joints is studied.In terms of the reliability during the operating process,the Darveaux model is established to predict the thermal fatigue life of the solder joints.What's more,the multi-objective optimization of residual stress and thermal fatigue life is carried out by grey correlation analysis based on entropy weight method,and the system optimization scheme of vertical interconnection reliability between substrates during manufacturing and operating process is proposed.