Multilevel Package Substrate Layout for Crack Arrest
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Solution Overview
Problem
Multilevel package substrates are prone to cracking due to rigidity and high die attach pad area, leading to degraded electrical performance and over mold or mold bleed defects, which cannot be adequately addressed by reducing mold height in designs requiring thick molded structures for insulation and accommodating tall dies.
Innovation Solution
Incorporating interleaved overlapping metal traces in adjacent metal stacks within the multilevel package substrate, with controlled spacing and overlap distances to mitigate crack formation and propagation, thereby enhancing structural strength and preventing cracks from propagating linearly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If mold height is reduced to reduce mold material volume and lessen force during molding, then molding force is reduced, but electrical insulation and accommodation of tall dies/components cannot be achieved
Solution Approach 1:
The patent transitions from a single-level substrate to a multilevel substrate architecture, adding vertical dimensionality with multiple metal stacks (first, second, third metal stacks) at different heights. This allows the substrate to maintain adequate thickness for electrical insulation while distributing structural stress across multiple levels, thereby reducing molding force requirements without sacrificing insulation capability.
Solution Approach 2:
The substrate is segmented into multiple independent metal stacks (first metal stack, second metal stack, third metal stack) rather than a single continuous structure. Each metal stack can be optimized independently for its specific function, and the segmentation allows stress to be distributed across multiple discrete structures rather than concentrated in one thick layer, reducing overall molding force while maintaining insulation.
2Force
If mold height is reduced to lessen force during molding, then molding force is reduced, but accommodation of tall dies and passive components cannot be achieved
Solution Approach 1:
By introducing multiple vertical levels (first level, second level, third level) with corresponding metal stacks, the substrate gains vertical adaptability. Tall dies and passive components can be accommodated on higher levels while the overall substrate structure maintains reduced height through the multilevel architecture, allowing accommodation of tall components without requiring proportional increase in total height that would increase molding force.
Solution Approach 2:
The multilevel segmentation allows different portions of the substrate to serve different functions: lower levels can accommodate standard-height components while upper levels provide accommodation for tall dies and passive components. This segmented approach enables selective accommodation of tall components only where needed, rather than requiring the entire substrate to be taller, thus maintaining lower overall height and reduced molding force.
3Strength
If multilevel package substrate uses rigidity and high die attach pad area, then structural strength is improved, but substrate cracking occurs along saw cutting lines and between adjacent metal stacks
Solution Approach 1:
The substrate is divided into multiple discrete metal stacks (first, second, third metal stacks) spaced apart from one another, rather than using a continuous rigid structure. This segmentation creates natural stress relief zones between the stacks, preventing crack propagation along saw cutting lines and between adjacent metal structures while maintaining structural strength through the distributed stack architecture.
Solution Approach 2:
The transition to multilevel metal stacks distributes structural support across multiple vertical levels rather than relying on a single rigid plane. This vertical distribution of strength allows the substrate to maintain structural integrity through the stacked architecture while reducing lateral stress concentrations that would otherwise cause cracking between adjacent metal stacks.
Data Source
AI summary
An electronic device includes a multilevel package substrate, a semiconductor die mounted to the multilevel package substrate, and a package structure that encloses the semiconductor die and a portion of the multilevel package substrate. The multilevel package substrate has a first level, a second level, a first metal stack, and a second metal stack. The first metal stack includes a first set of contiguous metal structures of the first and second levels, the second metal stack includes a second set of contiguous metal structures of the first and second levels, the first and second metal stacks are spaced apart from one another, a first metal trace of the first metal stack partially overlaps a second metal trace of the second metal stack, and the first and second metal traces are in different levels of the multilevel package substrate.