PCBs with different core materials assembling in vapor phase soldering technology

The increasing demand for high integration with continuous decreasing dimensions, maintaining quality and low cost for electronic modules brought on the market new types of printed circuits boards (PCBs), having different material core as substrate. Taking into account only rigid PCBs, glass for applications requiring high levels of cleanliness (medical apparatus) or dedicated to work in high humidity environmental conditions. In the practice, the EMS companies become to have difficulties for assembling the PCBs with glass core determined by high differences of the thermophisical properties compare to classical FR4, being hardly to adjust the SMT lines parameters. In this paper it is analyzed the influence of the PCB substrate thermophysical properties over lead-free solder joints quality and reliability as results of two soldering technologies, classical infrared-convection (IRC) and vapor phase (VPS). The experiments emphasize the differences regarding soldering thermal profile determined by the glass core of the PCB substrate. The optimum soldering solution for this PCB type will be provided. The results are undeniably that PCB support material is very important for the statement of the thermal profile of the process.