Second-level interconnects reliability as a function of PCB build-up

The aerospace and defense electronics industry leans henceforth on the technologies developed for consumer applications, particularly for digital boards. However, the requirements of aerospace and defense products in terms of reliability and mission profile are tougher than those for consumer ones. In addition, with the increase of circuit density in electronics and the arrival of new technologies of printed circuit boards (e.g. stacked microvia, embedded active components), the PCB build-up construction is more and more complex and becomes a critical element for the reliability of the solder joints of the electronic components assembled on PCB, also called second-level interconnects. The material characterization results showed that the physical data supplied by the manufacturers of base materials are not sufficient to represent the mechanical behavior of the PCB. The mechanical behavior of a whole PCB build-up is very dependent on its total resin and glass-fibers contents. The conclusions of this comprehensive design-of-experiments study demonstrate the impact of the PCB build-up construction on second-level reliability. In particular, test results point out the strong influence of the total resin-content, on the solder joints reliability of fine-pitch lead-less packages.