Incomplete fill for FlipChip design in MAP mold package

• Published in: 36th International Electronics Manufacturing Technology Conference pp. 1 - 5
• Main Authors: Chiew, Chong Chee, How, Chong Meng, Asentista, Calo Paularmand, Sidik, Norsuhaili Mohd
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.11.2014
• Subjects: Analytical models; Atmospheric modeling; Compounds; Flip-chip devices; Lead; Manufacturing; Temperature
• ISSN: 1089-8190; 2576-9626
• DOI: 10.1109/IEMT.2014.7123125

Various packaged ICs are widely used in semiconductor industry. To continue impress to the technology, the size and cost of electronic devices is focused in order to meet the need for small, yet attractive cost packaged ICs. One of its innovative ideas is to replace the traditional wire bonding interconnection with flip chip bonding which will provide alternative interconnect method to packaging ICs. During development of 2 different packages with flip chip interconnect, high defect rate on incomplete fill found on both packages after molding. This has endangered the committed customer time line which eventually affects company reputation if delayed. Thinking 6 Sigma is the systematic way to achieve High Performance Production and Business processes. In this paper, DMAIC approach which is one of the structured approaches of 6 sigma is demonstrated. The root cause of incomplete fill is defined through the visual verification, short shot analysis and mold flow simulation. The performance result from the short shot analysis and mold flow simulation indicated that the unique of incomplete fill in this case is due to the compound flow joint point where the air is trapped at the middle of package (L-shape area). As no air vent feature is present at the L-shape area and air trapped is not fully released with existing package pressure during molding, incomplete fill occurred. In order to identify levers that can be used for performance improvement, various statistical study on several aspects; package design (flip chip), lead frame's L-shape design, mold compound design and molding capability that may impact to the incomplete fill issue had been demonstrated. As for the package design (flip chip) study, it showed that the flipped chip placement is directly interrupting the mold compound flow direction and cause the incomplete fill at the affected location. As for the lead frame L-shape design, it is showed that the angle radius, relief and haft etch design is significantly impact to incomplete fill defect based on the Chi-squ and proportional statistical test. Also mold compound study, it is showed that smaller filler size compound showed less incomplete fill occurred based on proportional statistically test. Lastly, for the molding capability study, it is showed that mold operating temperature and plunger transfer time are significantly impact to the incomplete fill based on DoE statistical study. With the solution and improvement that are generated through the decision matrix, new package design with new lead frame L-shape design identified. The pilot run showed that the new package design able to eliminate the incomplete fill issue. In addition, confirmation run performed and result showed incomplete fill issue consistently eliminated.