Investigations on assembling of electronic packages onto glass substrates using lead-free technology

In the last decade new materials were launched on the market. This is the case of PCB substrates, also. Requirements for improved heat transfer between power components and the solid metal base led to a new PCB technology, on copper and aluminum substrates. Typical applications are those where high level of heat has to be dissipated from the circuit (in LED applications, for example). Requirements for a very clean environment led to create PCBs on glass substrate. Typical applications are for medical instruments, products and devices. Addressing only to SMT issues, the new materials are a challenge for conventional assembling technologies. High thermal mass of the substrate makes impossible the IR and convection reflow assembling, especially since the lead-free technology raised the process temperature. In this case, Vapour Phase Soldering (VPS) technology seems to be the most appropriate for obtaining the best assembling results. Using VPS and having broad knowledge in the management of assembling technologies and Design For Manufacturing (DFM) represent the key of success in case of PCB products based on glass. The paper presents the applied research performed in an assembly line based on VPS equipment, in order to define the design requirements for assembling circuits on glass substrate. Even for electronic medical applications the RoHS European Directive is not yet mandatory, this work is useful for the future, when lead-free products will cover also this area of electronics.