Epoxy removal is an important step when testing the performance of electronic components, and laser ablation is expected to be an ideal method for the efficient and non-destructive removal of epoxy resin because of its precision and control. This study reports the results of the systematic investigation of the influence of a 532 nm laser on the ablation of epoxy resin under different laser parameters using a response surface methodology. A multi-response surface model that considers the effects of the laser fluence, scanning speed, and scanning spacing on the removal rate and roughness during the laser ablation of epoxy resin is established using the central composite design method. The effects of single and multiple factors on the laser ablation of epoxy resin are analyzed. The results indicate that the optimal ranges for the laser fluence, scanning speed, and scanning spacing are 11.20?11.28 J/cm², 224?240 mm/s, and 1.50?1.55 μm, respectively, which result in a removal rate of 1620?1628 μm³/s and roughness range of 5.7?5.8 μm. The optimal parameters are the laser fluence of 11.20 J/cm², scanning speed of 234 mm/s, and scanning spacing of 1.50 μm. The study results confirm that optimized ceramic components inside electronic devices have lower surface damage, based on a comparative analysis of the micro-morphology, elastic modulus, and element content results of epoxy resin samples before and after parameter optimization. These results have significant value and meaning for the non-destructive testing of electronic components through accurate and efficient epoxy resin ablation.

A nanosecond laser with a wavelength of 532 nm, pulse width of 6 ns, and repetition frequency of 100 Hz is used to perform ablation tests on epoxy resin-coated electronic devices. Taking the laser fluence, scanning speed, and scanning spacing as input factors, and the roughness and removal rate as output responses, a mathematical?physical regression model of the removal rate and roughness with the above laser parameters is established using three-factor five-level full-response central composite design experiments. In addition, the process parameters needed to obtain the optimal removal effect are obtained, with the reliability of the model proven through validation experiments. The microscopic morphology of the samples after the removal of the epoxy resin is observed and analyzed using scanning electron microscope (SEM). The roughness and removal rate of the samples are measured and calculated using laser confocal microscope, and the elasticity modulus of the electronic device surface after removing the epoxy resin is measured using atomic force microscope (AFM). The parameter combination of smaller laser fluence (11.20?11.40 J/cm²), faster scanning speed (200?240 mm/s), and appropriate scanning spacing (approximately 1.50 μm) allows the laser to ablate the epoxy resin in a more moderate way, which results in a smaller roughness (Fig. 4). The average elastivity modulus of the electronic device surface after the removal of the epoxy resin is (318.0±10.5)GPa, and after optimizing the parameters, the laser ablation does no damage to the mechanical properties (Fig. 6).

The calculation results show that the optimum removal rate during the laser ablation is obtained with a laser fluence of 11.60?11.80 J/cm², scanning speed of 160?180 mm/s, and scanning spacing of 1.50?2.00 μm (Fig. 3). In this case, increasing the laser fluence increases the energy absorption rate of the epoxy resin, and decreasing the scanning speed increases the interaction time between the laser and material. In addition, decreasing the scanning spacing increases the overlap rate of the spot between rows and the energy of the laser irradiation per unit area. As shown by the SEM images, the surface of the laser-removed epoxy resin sample is relatively clean and tidy after the optimization of the parameters (Fig. 5). The elasticity modulus measured via AFM is (318.0±10.5)GPa, which demonstrates the low laser-induced damage to an electronic component during the removal of epoxy resin.

A mathematical?physical model of the laser ablation of epoxy resin is established by adopting the response surface method, and the effects of the process parameters and their interaction on the removal rate and roughness during the laser ablation of epoxy resin are systematically investigated. This leads to the optimum theoretical laser parameters for obtaining the maximum removal rate and minimum roughness. The calculation results show that the optimized removal rate and roughness during laser ablation are obtained at a laser fluence range of 11.20?11.28 J/cm², scanning speed range of 224?240 mm/s, and scanning spacing range of 1.50?1.55 μm. The obtained removal rate has a range of 1620?1628 μm³/s, and the roughness has a range of 5.7?5.8 μm. The optimal combination of parameters includes a laser fluence of 11.20 J/cm², scanning speed of 234 mm/s, and scanning spacing of 1.50 μm. The morphologies and mechanical properties of the removed epoxy resin samples before and after process optimization also confirm the feasibility of the method. These study results have important research value and significance for the efficient removal of epoxy resin via laser ablation and the development of nondestructive testing methods for electronic components.