Soldering tests with biodegradable printed circuit boards

The paper presents soldering tests on biodegradable printed circuit boards (PCB) focusing on different alternative base materials. The aim of the work was to investigate and optimize different low-temperature soldering profiles on cellulose-acetate (CA) and polylactide (PLA) biopolymer-based PCBs with the application of special lead-free solder alloy suited for the temperatures. The investigations were focused on the minimization of the heating effect on the heat-sensitive biopolymers, where on the other hand, sufficient thermal energy is required to melt the solder alloys. The soldering profiles were created with a custom vapour phase soldering (VPS) approach where the heat transfer is controlled with an adaptive height-setting, temperature tracking sample holder. The profiles were evaluated according to their heating factor values. The soldered joints were evaluated with X-Ray microscopy and Shear Tests. The deformation of the PCB tracks was also investigated. The preliminary results reveal the priority of CA for further experiments.