Use of Photonic Soldering to Enable High Quality Connections on Temperature Sensitive Substrates

Many prototypes have been developed in the flexible hybrid electronic space that do not go to production due to poor longevity of the final design. One of the big challenges remains how to connect conventional component to a flexible architecture, while maintaining the expected longevity in the circuit. Anisotropic conductors are the current benchmarks for these devices, but their performance is lacking as compared to standard soldering processes. PulseForge has devised a new photonic soldering process that enables attachment using standard solder pastes onto components and substrates that cannot withstand the oven reflow temperatures.
Photonic soldering utilizes high intensity flashes of visible light to achieve wide area heating with exceptional uniformity. Solder paste is heated to its liquidous temperature using radiative energy transfer, and light is converted to heat through optical absorption. This process is selective by exploiting selective absorptivity of active regions or with the aid of shadow masks. The optical flash can be modulated digitally, with high temporal resolution, to enable highly customizable temperature profiles, ranging from traditional to highly innovative.
Photonic soldering is compatible with standard high temperature lead free solder alloys (e.g. SAC305) in combination with temperature-sensitive substrates (e.g. PET). The nonequilibrium nature of the heating process enables thermal isolation of active regions from temperature sensitive regions. The resulting flexibility in material selection gives designers significant freedom and unconventional options in device architectures. The innovative approach enables a production flow that better lines up with the next generation of electronics. This presentation highlights the advantages of the new technology and discusses the application space for the photonic soldering technology.