Aspects on Advanced Thermal Management and Reliability for Flip Chip on LTCC

摘要

One of the major driving forces for the electronic industry is the consumer handheld units, where even more functions in a smaller volume and with longer battery time are requested. This leads to a higher energy- and interconnect density. One trend to manage the interconnect density is using Flip Chip (FC) technology which remarkably reduces the keep out area around the die compared to a wire bonded one. Two challenges related to this request, that the industry is facing, are thermal management and reliability. This paper will discuss some aspects of using FC-technology on Low Temperature Cofired Ceramics (LTCC) for this kind of products and will focus on the heat dissipation problem of an FC mounted die and the durability of solder bumps during thermal shock and thermal cycling. Test designs were developed and built to investigate SnAgCu (SAC) bumps on LTCC, underfill and five different LTCC designs. The LTCC design parameters were thermal vias and heatspreaders. In the experimental part the semiconductor junction temperature was measured over a diode in the semiconductor. Furthermore cross sections and infrared thermal imaging were used. The experiments were accompanied by FE-modeling using ANSYS workbench.