2D X-Ray Void Detection for Next Generation Copper Pillar Bump

As the complexity of the structure and the number of I/O pins increasing, in order to meet the demand, the bumps are became smaller and smaller [1]. For the newest technology development, the bump with a diameter of 13μm would gradually become mainstream size. Voids in 13μm bump are the most common defect [2]. 2D X-ray is an often used tool for bump void detection, because there is enough speed to detect defects and accurately detect it. At this stage, the 6~8μm void in 25μm copper pillar bumps can be easily detected by 2D X-Ray. However, traditional 2D X-ray can no longer meet the detection requirements for 13μm bump, so the newest 2D X-ray with high resolution and image recognition software is necessary.The machine resolution is 0.4μm by JIMA gauge test and the high heat dissipation target with nano-focus system. Nano-focus system with small focal spot, as the focal spot is reduced in size, the energy density at the target increases by the square. Therefore, heat energy of high heat dissipation target can be dissipated and it is not easy to damage the target. For void inspection, image recognition software is deemed necessary because eyes can distinguish only about 256 gray scales. However, there are 65,536 gray scales for the new 2D X-ray and can be effectively identified by software. This paper mainly discusses the detection capabilities and limitations of 13μm bump void in 2D X-ray, and the minimum 5μm void can be detected. Finally, the possible improvements will be provided with current trends.