Hot bar joining method for medical applications

The goal is to use the hot bar method to join the conductive lines of a flexible interposer with copper wires, which are located inside of the catheter wall. These copper wires with a diameter of 150 μm were integrated during the extrusion process of a polyethylene catheter with a diameter of 3 mm and a wall thickness of 1 mm. The wires will be used as signal and power lines. Because the copper wires located inside the catheter wall, the polyethylene material above the copper wires must be removed for joining the interposer copper lines. The material ablation was done by a femtosecond laser. Detailed knowledge about the heat sensitive handling with the polyethylene catheter must obtained before start the joining procedures. For the setup of the final joining procedure, there were used different types of test vehicles. With the help of the test vehicles the joining method is evaluated. Therefore, a hot bar stamp is placed at the back of the polyimide layer. The investigated parameters of the hot bar are stamp temperature, stamp force and time. After the setup analysis of the sensor test vehicle, the optimal joining parameters will be discovered and the flexible interposer and the copper wires inside of the catheter wall could be joined in future steps. Finally, non-destructive (ultrasound, x-ray) and destructive methods (tweezer pull test, microsection) will be investigated to evaluate the joining quality and quantity of the test vehicle and the final sensor catheter.