Chip Package Conductive Pillar Density for Lift-off Stress
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Solution Overview
Problem
In the semiconductor package manufacturing process, the conductive pillars adjacent to the lift-off end of the chip package structure are subjected to greater lift-off stress, leading to potential damage during the separation from the substrate, which affects their reliability.
Innovation Solution
The chip package structure incorporates a higher density of second conductive pillars along the edge compared to first conductive pillars, with the second conductive pillars being placed closer to the lift-off end to absorb and distribute the lift-off stress, enhancing their structural strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the chip package structure is separated from the substrate during the lift-off process, then the chip package structure can be obtained for further processing or use, but the conductive pillars adjacent to the lift-off end are subjected to greater stress and are more likely to be damaged
Solution Approach 1:
The patent applies local quality by creating a dual-density conductive pillar structure where the density of conductive pillars varies by location. Specifically, a first density of conductive pillars is arranged in a first region, and a second density of conductive pillars is arranged in a second region. This non-uniform distribution allows the structure to have different mechanical properties in different areas, with higher density regions providing enhanced stress resistance where needed during the lift-off process.
Solution Approach 2:
The patent implements parameter changes by modifying the density parameter of conductive pillars across different regions. The first density and second density are deliberately different, with the second region having a higher pillar density to compensate for the increased stress it experiences during substrate separation. This parameter variation optimizes the overall reliability of the chip package structure during manufacturing.
2Strength
If the density of conductive pillars is increased to improve structural strength and stress distribution, then the reliability during lift-off is improved, but the manufacturing complexity and material usage increase
Solution Approach 1:
The patent applies segmentation by dividing the conductive pillar arrangement into distinct regions with different densities. The first region contains conductive pillars at a first density, while the second region contains conductive pillars at a second density. This segmentation allows the design to achieve enhanced strength where needed without uniformly increasing complexity across the entire structure, making the manufacturing process more manageable.
Data Source
AI summary
A chip package structure includes a chip package layer and at least one conductive structure layer. The chip package layer includes at least one chip and an encapsulant. The chip has an upper surface, and the encapsulant is used to encapsulate the chip and expose the upper surface. The conductive structure layer includes a plurality of first conductive pillars and a plurality of second conductive pillars. The first conductive pillars are disposed on the upper surface, the second conductive pillars are disposed on the upper surface and located between an edge of the upper surface and the first conductive pillars. A density of the second conductive pillars along an extending direction of the edge is greater than or equal to 1.2 times of a density of the first conductive pillars along the extending direction of the edge.