| Summary: | 碩士 === 國立臺北科技大學 === 機電整合研究所 === 103 === There will always be internal stress produced on a substrate during electroplating and it will cause deformation of the substrate. Large internal stresses will cause cracks or reduce the coating adhesion. There are many internal stress real-time measurement devices in industry. In the present study, we use the concept of using radius of curvature to measure internal stress proposed by Stoney to design a real-time internal stress measurement device. The volume change of water compartment due to specimen bending by the internal stress is represented by wa-ter column height and then this value of water column height is plugged into a formula to calculate the stress value. This concept has many advantages, such as low cost, easy operation, rapid response and wide application. There are many factors that can cause inaccuracies during measurement compared with mean re-sults, such as capillary action in the water tube, which caused 1~2 mm water column height error; different specimen measurement results had a 7% maximum error; manual repetition of measurement set up with same specimen had a 3% maximum error; when the device went into a 50°C bath for repeatability meas-urements, the change in water height due to heating or cooling of the whole de-vice had a 13% maximum error compared with mean results under the same en-vironment temperature and convection conditions. Tensile stress measurements in a constant bath temperature had a difference of 38.7 MPa. When compared with bend strip method, tensile stress measurements in the 50°C bath temperature had a difference of 20.7 MPa. Compressive stress measurements in the constant bath temperature had a difference of 24.0 MPa. Compressive stress measurements in the 50°C bath temperature had a difference of 11.5 MPa. During the early stages of thin-film growth in the electroplating process, lattice misfit stresses resulting from distortion due to differences in lattice parameters at the interface between the coating and substrate will cause large internal stress. The internal stress can transform from tensile to compressive by introducing saccharin into the electroplating bath.
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