提出了一种测试电沉积应力演变的方法.其机理为当带金属包层的布喇格光纤光栅为阴极进行电沉积时,在沉积应力作用下,布喇格光纤光栅的中心波长将发生漂移,以此可推知沉积应力的大小.测试中首先利用光纤光栅解调仪记录电沉积应力作用下的布喇格光纤光栅中心波长的偏移量,并将整个沉积时间分成小的时间段;然后依据沉积速度和标定的不同沉积厚度下的布喇格光纤光栅应力灵敏度,计算出每时间段的应力值;最后将各时间段应力累加以获得累积应力随时间的演变.以电镀镍为例,使用涂覆有化学镀镍磷金属包层的布喇格光纤光栅传感器,进行电沉积应力测试,测试表明:当测试镍镀层厚度小于50μm时,传感器灵敏度大于7pm/MPa,准确度大于0.14 MPa;在6 000s的电镀时间内,累积压应力为173.049 9 MPa.
A novel method for measuring electrodeposition stress was presented.Its mechanism is that the center wavelength of metal coated Fiber Bragg Grating sensor shifts under the action of the electrodeposition stress when the FBG is used as cathode in electrodeposition;based on the shift,the stress can be calculated.In the measurement,the center wavelength shifts of the FBG during deposition are recorded by FBG interrogator and these records are divided into many time segments with equal interval.Based on average depositing velocity and the relationship of FBG′s stress sensitivities with deposition thickness,the stresses producing in every time segment are calculated individually.Stress evolution is obtained by adding up these segmental stresses.The process is stress evolution during electroplating nickel was tested by using electroless Ni-P coated FBG sensor.The result shown that the FBG′s sensitivity is higher than 7pm/MPa under the condition that the nickle thickness is less than50μm,and the degree of accuracy is more than 0.14 MPa.After deposition for 6 000 s,the accumulative pressure stress is 173.049 9 MPa.