波前传感器电铸镍层应力实时检测精度评估

Accuracy Evaluation of Real-time Detection on Internal Stress of Nickel Electroforming Based on Wave Front Sensor

目的搭建电铸应力实时检测平台,评估其测量精度,并探明电化学沉积过程中镍层平均内应力的变化规律。方法采用横向剪切波前传感器搭建电铸应力实时检测平台,通过测量在铸层应力作用下电铸基底弯曲的曲率半径,利用Stoney公式计算铸层平均应力。采用参考球面反射镜评估横向剪切波前传感器曲率半径的测量精度,并在0.5 A/dm^2电流密度下进行电铸应力实时检测实验,对铸层平均应力测量极限进行评估,同时对检测误差进行分析。结果横向波前传感器曲率半径测量精度为99.22%,在0.5 A/dm^2电流密度下,所搭建的铸层应力实时检测平台可测量的最小厚度为5.1μm,由曲率测量波动带来的应力检测误差为1.3 MPa。实验测得铸层平均应力随铸层厚度的增加而变大,当铸层厚度达到30μm左右,铸层平均应力趋于稳定,应力大小为79.7 MPa。同时发现,当铸层厚度小于30μm时,沿电铸基底长度方向的铸层平均应力明显大于宽度方向铸层平均应力,随铸层厚度的增加,两个方向的应力大小趋于等值。结论采用横向剪切波前传感器搭建的电铸应力检测平台,能有效对铸层应力进行高精度的实时测量,为精密电铸过程中应力变化规律的研究提供了检测技术基础。

The work aims to build a real-time detection platform of electroforming stress to evaluate the measurement accuracy and verify the variation laws of the average internal stress of the nickel coating in the process of electrochemical deposition.Lateral shear wave front sensor was used to build a real-time detection platform of electroforming stress and then calculate the average stress of the electroforming layer with Stoney formula by measuring the radius of curvature of electroformed substrate under the electroforming layer stress.A reference spherical mirror was adopted to evaluate the measurement accuracy of the radius of curvature of the lateral shear wave front sensor,and the average stress measurement limit and the detection accuracy of the electroforming layer were evaluated by carrying out real-time detection experiment to the internal stress of electroforming layer under the current density of 0.5 A/dm^2 and the detection error was analyzed at the same time.The measurement accuracy of radius of curvature of lateral shear wave front sensor was 99.22%.Under the current density of 0.5 A/dm^2,the measureable minimum thickness of the real-time detection platform built for internal stress of electroforming layer was 5.1μm,and the measurement error of internal stress brought by fluctuations of measured curvature was 1.3 MPa.The experiment illustrated that the thicker the electroforming layer was,the more intensified the average stress of electroforming layers was.When the thickness of the electroforming layer reached about 30μm,the average stress of electroforming layers was stabilized,with the stress of 79.7 MPa.Meanwhile,if the thickness of layer was under 30μm,the average stress of electroforming layer along the length of electroforming base was much more intensified than that along the width.As the increasing of the thickness of the electroforming layer,the average stress of electroforming layer in two directions tended to be the same.The real-time detection platform for internal stress of electroforming layer built by a lateral shear wave front sensor can effectively carry out high-precision real-time measurement to the stress of electroforming layers,which provides a detection basis for the study of stress variations in the process of precision electroforming.