Package Substrate Pad Metallization for Higher Routing Density
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Solution Overview
Problem
As integrated circuit (IC) packages require increased signal routing density, adding additional metallization layers to support this density leads to an undesired increase in overall package thickness, which can exceed thickness requirements.
Innovation Solution
Incorporating a dedicated pad metallization layer with metal pads for external connections, which reduces the thickness of adjacent metallization layers by allowing smaller width metal interconnects for internal signal routing, thereby increasing signal routing density without significantly increasing package thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If additional metallization layers are added to support increased signal routing density, then signal routing capacity is improved, but overall package thickness increases
Solution Approach 1:
The metallization structure is segmented into two distinct types: standard metallization layers for internal signal routing and a dedicated pad metallization layer for external connections. This segmentation allows each layer type to be optimized independently, enabling the pad layer to use thinner construction while maintaining external connection functionality, thus increasing overall routing density without proportionally increasing package thickness.
Solution Approach 2:
The pad metallization layer serves multiple functions: it provides external connection pads, establishes electrical connections to internal metallization layers through vias, and contributes to the overall signal routing architecture. This multi-functionality allows a single layer to accomplish what would traditionally require multiple layers, improving routing capacity while controlling thickness.
2Quantity of substance
If the number of metallization layers is increased to accommodate higher density signal routing paths, then signal routing capacity is improved, but IC package thickness increases
Solution Approach 1:
Different metallization layers are assigned different local qualities and functions: standard metallization layers are optimized for internal signal routing with appropriate thickness and trace dimensions, while the pad metallization layer is optimized for external connections with thinner construction. This local differentiation allows the system to achieve high overall routing capacity without requiring all layers to be thick, thereby controlling package thickness while supporting increased quantity of signal routing paths.
Data Source
AI summary
Package substrates employing a pad metallization layer for increased signal routing capacity, and related integrated circuit (IC) packages and fabrication methods. To support increased signal routing density in an IC package while mitigating an increase in overall IC package thickness, an outer metallization layer of the package substrate is provided as a thinner, pad metallization layer. A metal layer in the pad metallization layer includes metal pads for forming external connections to the package substrate. This allows an area in the adjacent metallization layer that would otherwise have larger width metal pads for forming external interconnects, to be used for other signal routing within the package substrate. This can increase the overall signal routing density of the package substrate while mitigating the increase in overall package substrate thickness if a full-sized additional metallization layer were added to the package substrate.