Interposer Cavity Geometry for Void-Free Semiconductor Packaging
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Solution Overview
Problem
In semiconductor package manufacturing, the edge portions of cavities formed under interposers can disrupt the flow of fluids during cleaning and molding processes, leading to voids and increased package size.
Innovation Solution
A semiconductor package design featuring an interposer with a cavity and spacers having inclined sidewalls and side surfaces, which allows for the accommodation of semiconductor devices without disturbing fluid flow, enabling reduced package size and preventing void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a cavity is formed under the interposer to accommodate the semiconductor chip, then the size of the semiconductor package is reduced, but the edge portion of the cavity disturbs the flow of fluids such as cleaning agent and molding member
Solution Approach 1:
The cavity sidewall is designed with an inclined surface (curved or angled) instead of a vertical edge, and the spacer is provided with a rounded head portion. This curvature eliminates sharp edges that disturb fluid flow, allowing cleaning agents and molding members to flow smoothly through the cavity region without creating turbulence or voids.
Solution Approach 2:
The inclination angle of the cavity sidewall is optimized to balance two requirements: it must be steep enough to maintain compact package size but gentle enough to allow smooth fluid flow. By adjusting this geometric parameter, the design achieves both volume reduction and fluid flow compatibility.
2Volume of moving object
If the cavity has vertical sidewalls to maximize space utilization, then the package size is minimized, but voids are generated due to disturbed fluid flow
Solution Approach 1:
The inclined cavity sidewall and rounded spacer head eliminate sharp corners and vertical edges that cause fluid flow separation and vortex formation. This curvature ensures laminar flow of cleaning agents and molding members, preventing void entrapment while maintaining compact package dimensions.
Solution Approach 2:
The inclined cavity sidewall, which initially appears to reduce space utilization, actually improves the process by enabling smooth fluid flow. The design converts the potential harm of reduced space efficiency into a benefit of void-free manufacturing, achieving both goals through optimized geometry.
3Volume of moving object
If the spacer has a vertical side surface to maximize cavity depth, then the accommodation space is increased, but the flow of cleaning agent and molding member is disturbed
Solution Approach 1:
The spacer head portion is designed with a rounded, curved surface instead of sharp edges or vertical sides. This curvature allows fluid to flow smoothly over and around the spacer, preventing flow separation and turbulence. The inclined cavity sidewall complements this by providing a gradual transition that maintains laminar flow throughout the cavity region.
Data Source
AI summary
A semiconductor package includes a package substrate, a first semiconductor device on the package substrate, an interposer on the package substrate, and a plurality of conductive structures that spaces apart the first semiconductor device from the interposer, wherein the interposer has a cavity into which a portion of the first semiconductor device is accommodated. The interposer has a plurality of spacers protruding from a bottom surface of the cavity of the interposer. The cavity has an inclined sidewall inclined at a predetermined angle with respect to the lower surface of the interposer. The spacer has an inclined side surface inclined at a predetermined angle with respect to the bottom surface of the cavity.