A novel approach for the removal of oxide film to achieve seamless joining during hot-compression bonding

The oxide film on the substrate surfaces can severely hinder the bonding quality during hot-compression bonding (HCB). To address the above issue, this investigation proposes a novel approach to enhance bonding quality by removing surface oxide film and encapsulating the interface to be bonded in sequence under vacuum. The principle of the approach was clarified, and an experiment platform used for implementing the approach was designed and developed. By considering 316H stainless steel as a testbed, the key parameter for laser ablation of the oxide films before HCB was determined. The HCB comparative experiments of substrates with or without treatment by the approach were carried out and the effectiveness of the approach was assessed by comparing the quality of bonding joints through interface morphologies and tensile properties. Results showed that a nearly seamless bond without thermal holding was achieved after adopting this approach. Further, it also showed improvement in the tensile properties both in elongation and the ultimate tensile strength (UTS). For instance, when using the proposed approach, the average UTS of 316H stainless steel joints improved from 371.17 MPa to 430.25 MPa whereas the average elongation increased from 26.41% to 64.04%. Although this investigation was directed to 316H stainless steel, the suggested approach can be applied to a wide range of other engineering materials to improve the joining quality.