Wiring Substrate Via Receiving Electrode Segmentation
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Solution Overview
Problem
Current wiring substrates face challenges in increasing wiring density in lower wiring layers without requiring high-level photolithography technology, as the presence of via pads inhibits this increase and demands significant capital investment and process changes.
Innovation Solution
The design incorporates via receiving electrode portions with a smaller area than the connection pad, allowing for a wiring portion to be arranged in the extra space, connected by via conductors, which can be patterned using existing photolithography technology, thereby increasing wiring density without the need for advanced technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If via pads are arranged with equal area to connection pads in lower wiring layers, then interlayer connection is provided, but wiring density of lower wiring layers cannot be increased
Solution Approach 1:
The via pad in the lower wiring layer is divided into multiple via receiving electrode portions (first, second, third, and fourth via receiving electrode portions) instead of using a single large via pad. This segmentation allows multiple via conductors to be arranged in the lower wiring layer within the area corresponding to the connection pad, thereby increasing wiring density while maintaining reliable interlayer connections through each via receiving electrode portion.
2Productivity
If narrower pitch of lower wiring layers is implemented to increase wiring density, then high-level photolithography technology is needed, but huge capital investment and process change are required
Solution Approach 1:
Instead of reducing the pitch (horizontal dimension) of lower wiring layers which would require advanced photolithography, the patent utilizes the vertical dimension by arranging multiple via receiving electrode portions at different positions beneath the connection pad. This allows increased wiring density through vertical stacking and spatial arrangement in the thickness direction, achievable with existing photolithography technology.
3Reliability
If via pads are arranged with equal area to connection pad, then interlayer connection is ensured, but the presence of via pads inhibits increase in wiring density
Solution Approach 1:
The via pad area is segmented into multiple smaller via receiving electrode portions distributed beneath the connection pad. This segmentation increases the total number of via conductors that can be arranged in the lower wiring layer while maintaining sufficient area for each via receiving electrode portion to ensure reliable interlayer connection, thereby increasing wiring density without compromising connection reliability.
Data Source
AI summary
A wiring substrate includes a wiring layer, an insulating layer formed on the wiring layer, a connection pad formed on the insulating layer, and a via conductor formed to penetrate the insulating layer, and connecting the wiring layer and the connection pad, wherein the wiring layer located under the connection pad is formed to have via receiving electrode portion whose area is smaller than an area of the connection pad, and a wiring portion separated from the via receiving electrode portion, in an area corresponding to the connection pad, and the via receiving electrode portion is connected to the connection pad via the via conductor.