| dc.description.abstract | The purpose of this study is using a 0.09 mm-diameter drill to investigate the drilling characteristics in an in-circuit-test (ICT) probe plate for printed circuit board (PCB). Through Taguchi Method, four control factors, namely rotational speed, feed rate, drilling method, and cutting fluid, are selected to conduct designed experiments and analyze the results of drilling force, drill hole position precision, accuracy of hole diameter, and drill life. Accordingly, an optimal combination of working parameters for the given drilling task is determined and verified.
A Taguchi Orthogonal Array is selected to design and conduct 9 runs of drilling experiment. Experimental results indicate that drilling force plays an important role in determining the number of holes drilled and wear of drill. Taguchi Method is then applied to calculate the S/N ratios of the data in measuring drill hole position and diameter. As a result, the optimal control factor combination for drill hole position precision is A2B2C1D3, i.e. A2 with rotational speed of 12,000 rpm, B2 with feed rate of 6,000 mm/min, C1 with drilling mode of (a) deep-hole drilling cycle, G83, and D3 with cutting fluid ratio of one liter of cutting fluid and 30 liters of water. On the other hand, the optimal combination of control factors for accuracy of hole diameter is A2B1C3D2, i.e. A2 with rotational speed of 12,000 rpm, B1 with feed rate of 5,000 mm/min, C3 with drilling mode of (c) chip breaking drilling cycle, G73, and D2 with cutting fluid ratio of one liter of cutting fluid and 20 liters of water. Two more experiments using the drilling parameters A2B2C1D3 and A2B1C3D2 are conducted and the results indicate that such two combinations of control factors indeed generate a better performance than the originally designed 9 runs of drilling experiment. The verifying experiments also show that the A2B1C3D2 combination generates better results than the A2B2C1D3 combination. The overall comparison reveals that A2B1C3D2 is the optimal combination of working parameters for drilling holes in the given ICT probe plate of PCB.
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