DETECTING AND ANALYZING WAFER BUMP VOIDS WITH X-RAY INSPECTIONAuthor: Dr. Udo E. Frank
Company: FEINFOCUS GmbH
Date Published: 10/10/2004 Conference: IWLPC (Wafer-Level Packaging)
X-ray imaging technology can now detect and measure voids within solder bumps on chips, and determine the viability of the component based on pre-set threshold values. The X-ray inspection system converts 3D voids to measurable 2D images, enabling the system to calculate the ratio of the size of the void(s) within a solder bump to the total mass of the ball. The system can also determine the largest linear distance between two points in the void and compare the result with the diameter of the ball. Depending on the parameters pre-established by the operator, the solder bump is deemed acceptable (capable of providing a reliable and sufficient interconnect) or unacceptable. Either method of analysis can be employed and used as criteria for determining the expected performance of the ball.
This new inspection technology ensures solder bump integrity while reducing the scrapping of viable components due to minor voids. The X-ray system employs an efficient inspection process, as once a solder bump is deemed defective, no further inspection of the component is necessary.
This report describes inspection of wafer bumps using a specialized high-resolution X-ray inspection system, compares the technology with traditional X-ray imaging, and provides details pertaining to wafer handling, operation of the equipment, software, configuration options, data analysis, and generation of reports.
Key words: X-ray inspection, wafer bump inspection, solder bumps.
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