Tapered Via Hole Structure for Dense Substrate Interconnects
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Solution Overview
Problem
The reduction in size of via holes in substrates for electronic components leads to defects in metal layer formation, causing electrical disconnection between pad parts, while increasing the size of via holes decreases component density, making miniaturization difficult.
Innovation Solution
A substrate design with a via hole structure featuring a lower hole with increasing width and an upper hole with decreasing width, connected by a conductive pattern, formed using different insulating layers and lasers to optimize metal layer formation and prevent area increases in pad parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the size of the via hole is reduced, then the area occupied by pad parts is decreased, but the metal layer may not be fully formed in the via hole causing electrical disconnection
Solution Approach 1:
The via hole is divided into two segments: a lower hole portion extending from the first insulating layer to the interface with the second insulating layer, and an upper hole portion extending from the interface through the second insulating layer to expose the upper pad part. This segmentation allows each portion to be optimized independently for its specific function.
Solution Approach 2:
Different width characteristics are applied to different portions of the via hole. The lower hole portion has a width that increases from bottom to top, providing stability at the base and gradual expansion upward. The upper hole portion has a width that decreases from bottom to top, creating a tapered structure that facilitates metal layer formation and ensures reliable electrical connection at the upper pad interface.
2Reliability
If the size of the via hole is increased, then the metal layer can be fully formed, but the areas of pad parts must be increased decreasing component density
Solution Approach 1:
The via hole structure employs dynamic width variation along its length rather than a uniform static width. The lower hole portion expands upward while the upper hole portion tapers downward, creating an optimized profile that adapts to the different requirements at each level without requiring increased pad part areas.
Solution Approach 2:
The solution moves from considering only the cross-sectional area (2D) to incorporating the vertical dimension (3D) in the via hole design. By varying the width along the depth of the via hole, the structure achieves adequate metal layer formation volume while maintaining small pad part footprints at the surface level.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces defects in the connection conductive pattern and prevents area increases in pad parts, ensuring reliable electrical connections and maintaining high component density, thus enabling miniaturization of electronic components.
Implementation Method 1
forming a sub-hole by primarily removing the second insulating layer and the first insulating layer by emitting a first laser
Implementation Method 2
forming a via hole by secondarily removing the second insulating layer and the first insulating layer by emitting a second laser different from the first laser
Data Source
AI summary
A substrate includes: a first insulating layer; a second insulating layer disposed on the first insulating layer; and a via hole including a lower hole formed in the first insulating layer, and an upper hole formed in the second insulating layer and connected to the lower hole, in which a width of an upper side of the lower hole is larger than a width of a lower side of the lower hole, and a width of an upper side of the upper hole is larger than a width of a lower side of the upper hole.