| Summary: | 碩士 === 元智大學 === 機械工程學系 === 95 === Moiré method is widely used for both the out-of-plane and in-plane surface measurements. It has advantages of fast, high precision, full-field, non-contact, and easy to set up. However, the extension of its use still needs to be explored with some research efforts. The study will develop the techniques of Moiré method in measuring the micro size and large size surfaces. The typical micro sized solder ball pad of the IC packaging and the large sized light guide plate of LCD backlight module are used as the study examples. For the former, the specification in its depth is around 10μm. This dimension is critical since it will affect the contact between solder ball and pad thus also influences the circuit connecting quality. While for the latter, the problem is due to the thinning of light guide plate currently always causes the surface warpage. This will affect the uniformity of the light which passes through the light guide plate. Other than these, the improvement of the experimental results by using different light sources is also investigated.
For the development of micro projection Moiré system, a series of optical devices is set up right in front of the optical microscope. It includes a self-made precision film grating to project onto the optic microscope. This projected grating together with the digital image process technique and phase algorithm can then solve for the surface measurement of the micro sized pad. In the case of using Shadow Moiré for the large size surface measurement, the warpage of the light guide plate is measured after the setting up of related devices and the use of the phase algorithm for the calculation. Besides, the three partial coherent light sources are tested and the contrast among the resulted fringe patterns are compared with for the best performance in the Shadow Moiré measurement.
The experimental results show that the data of pad measurement is within 8% difference when comparing with that of the specification. It is also reveals that with denser fringe patterns, the correctness of the reconstructed measured surface will be improved. Also, the higher contrast of fringe pattern on the light guide plate is observed when the blue light is used as the light source. Finally, for checking the precision of the measurement, the laser displacement sensor is adopted for point by point measurement, It is found that the difference only lies between 1μm~150μm when the light guide plate having warpage at some millimeters range. It is concluded that the developed Shadow Moiré systems have high accuracy for the precision measurement purposes.
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