Near-Infrared LED Reflow Soldering for Flexible Hybrid Electronics [Photo-AVT]
- Flexible Hybrid Electronics (FHE) is the combination of film substrates with etched or printed conductors and conventional SMT components. A particular focus has been placed on thermoplastics such as polyethylene terephthalate (PET) as a low-cost substrate material. However, the use of these materials in standard reflow soldering processes remains a challenge. In addition to the substrate's limited temperature resistance, the dissolution of printed silver conductors in the molten solder over time presents a further challenge.
The approach presented in this work uses multiple individually controllable Near Infrared LEDs as an energy source to selectively irradiate and thus locally heat FHE assemblies as required. Irradiation is applied from below through the substrate material, thereby enabling direct heating of the solder joint whilst preventing shading by the component body. The temporal and local controllability of the irradiation allows the placement density and the omission of temperature sensitive areas to be taken into account.Flexible Hybrid Electronics (FHE) is the combination of film substrates with etched or printed conductors and conventional SMT components. A particular focus has been placed on thermoplastics such as polyethylene terephthalate (PET) as a low-cost substrate material. However, the use of these materials in standard reflow soldering processes remains a challenge. In addition to the substrate's limited temperature resistance, the dissolution of printed silver conductors in the molten solder over time presents a further challenge.
The approach presented in this work uses multiple individually controllable Near Infrared LEDs as an energy source to selectively irradiate and thus locally heat FHE assemblies as required. Irradiation is applied from below through the substrate material, thereby enabling direct heating of the solder joint whilst preventing shading by the component body. The temporal and local controllability of the irradiation allows the placement density and the omission of temperature sensitive areas to be taken into account. This approach enables a more material-friendly and energy-efficient soldering process.…
