金 属 铜 的 水 导 激 光 加 工 机 理 与 工 艺 研 究（特 邀）

Objective Copper (Cu), with its superior thermal and electrical conductivity properties, is extensively utilized in high-power electronic packaging and thermal management modules. However, its inherent characteristics of high thermal diffusivity and strong optical reflectivity present considerable challenges for achieving precise machining using either conventional or non-conventional fabrication methods independently. This research introduces a cutting methodology based on water-jet guided laser (WJGL) technology, wherein a collimated laser beam transmits through a high-speed water jet, enabling stable beam delivery and concurrent convective cooling of the machining zone. This method enhances both machining precision and thermal damage control. However, the WJGL process encompasses complex multiphysics interactions, particularly involving thermodynamic, fluid dynamic, and photothermal fields, which complicate the understanding of fundamental laser‒Cu interaction mechanisms. Thus, the laser ablation behavior of Cu under WJGL conditions requires further investigation. A systematic examination of the governing ablation mechanisms and optimization of process parameters remains crucial for achieving high-quality, efficient machining of Cu components. Methods A WJGL cutting approach specifically designed for Cu substrates was developed to address the challenges posed by Cu’s high thermal conductivity and reflectivity during laser processing. The research established a three-dimensional thermo-optical model for WJGL ablation of Cu, accompanied by experimental studies to understand the interaction mechanisms between the WJGL energy field and Cu. Subsequently, single-factor experiments were conducted to examine the effects of critical parameters, including single-pulse energy, repetition rate, scanning speed, and water pressure, on Cu removal morphology. The research further analyzed parameter interactions through response surface methodology (RSM) to determine optimal processing parameters for efficient and stable cutting performance. Results and Discussions The comprehensive analysis of WJGL processing of Cu through mathematical modeling and experimental investigation revealed several significant findings. The validated WJGL ablation model demonstrated that the water jet functions both as an optical waveguide for laser beam delivery and as a thermal diffusion suppressor on the Cu surface, thereby minimizing heat-affected zones (HAZs) in non-target regions (Fig. 5). The research characterized the relationship between groove depth and scanning speed variations systematically (Fig. 7). Single-factor experiments revealed the distinct effects of key process parameters on groove dimensions and morphology (Fig. 8). The RSM analysis of parameter interactions identified optimal processing conditions: single-pulse energy of 3.5 mJ, repetition rate of 9 kHz, scanning speed of 3 mm/s, and water pressure of 19 MPa (Table 9). These optimized parameters enabled the production of Cu grooves with an aspect ratio reaching 23∶1 through single-pass scanning experiments (Fig. 17). Conclusions This study systematically investigates the characteristics of WJGL processing of Cu through a combination of mathematical modelling and experimental validation. The key findings are as follows: (1) A predictive erosion model for WJGL ablation of Cu was established, demonstrating that the water jet serves as an effective thermal regulator by constraining the surface temperature distribution of the material. This mechanism substantially suppresses HAZs and thermal damage in regions outside the laser focus. Comparative analysis between groove engraving experiments conducted at varying scanning speeds and corresponding numerical simulations reveals a high degree of consistency in the depth profiles, thereby validating the reliability of the proposed model. (2) Through the integration of single factor experiments and RSM, this study systematically evaluated the influence of critical process parameters, including single-pulse energy, repetition rate, scanning speed, and water pressure, on groove geometry and surface morphology. The research identified optimal parameters that facilitate the production of high aspect ratio Cu grooves (aspect ratio up to 23∶1) while preserving structural integrity and processing quality. This investigation establishes theoretical and empirical foundations for the high-quality fabrication of deep, narrow Cu groove structures. Additionally, it presents strategic guidelines for process optimization to enhance ablation depth and enable full-thickness cutting of Cu materials in advanced manufacturing applications.