Ultrasonic welding packaging of FBG and its bending sensing characteristics

In order to obtain metal foil packaged FBG sensor, FBG was firstly electroless-electroplated with a nickel layer and then packaged in 6061 aluminum foil by ultrasonic welding. After that, the tensile strength of the ultrasonic welding and the embedding strength of the metallized FBG were measured by tensile shear test. Moreover, spectral characteristics, temperature sensing property and bending strain sensing properties of the FBG were also studied in the study. Experimentally, when welding pressure was 5.4 MPa, welding time was 45 ms and coating thickness was 45 μm, the welded encapsulation exhibited a good effect; the average tear strength of aluminum foils reached up to 58.96 N, and the tensile shear strength of metallized FBG embedded aluminum foils reached up to 8.89 N. The results shown that after packaging, the FBG still maintained good waveform. Moreover, the average temperature sensitivity reached up to 29.07 pm/℃ and the average strain sensitivity reached up to 0.0967 pm/με.