Interconnect Substrate Groove Structure for Low-Capacitance Pads
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Solution Overview
Problem
Conventional interconnect substrates face challenges in reducing the area of external connection pads without altering the size of the insulating layer opening, which affects capacitance and compatibility with existing circuit substrates.
Innovation Solution
The interconnect substrate design features a pad with a groove around it, where the bottom surface of the groove is formed by the insulating layer and positioned deeper than the pad's surface, allowing the pad's outer edge to be inwardly moved beyond the insulating layer's perimeter, reducing the pad's upper surface area and capacitance while maintaining compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the area of the upper surface of a pad is reduced to reduce capacitance, then capacitance is reduced, but the size of the insulating layer opening must also be reduced which affects compatibility with conventional substrates
Solution Approach 1:
The invention introduces a groove structure that adds a vertical dimension to the pad configuration. The groove extends downward from the upper surface, allowing the pad's upper surface area to be reduced while the insulating layer opening perimeter remains unchanged. This dimensional transition enables capacitance reduction without compromising compatibility, as the groove's depth creates additional capacitance reduction capability independent of the planar dimensions.
2Reliability
If the outer edge of a pad is moved inwards away from the perimeter of the insulating layer opening, then capacitance is reduced, but it becomes difficult to achieve the desired configuration
Solution Approach 1:
The invention segments the pad structure into distinct functional zones: the upper surface area and the groove region. By separating these functions, the pad can maintain its electrical connection function while the groove provides the capacitance reduction function. This segmentation allows the outer edge to be moved inward more easily because the groove structure compensates for the reduced upper surface area, making the configuration both achievable and effective.
3Adaptability or versatility
If the perimeter of the insulating layer opening is kept unchanged to maintain compatibility, then compatibility is maintained, but the pad area cannot be reduced sufficiently to achieve desired capacitance reduction
Solution Approach 1:
The groove structure introduces a vertical dimension that enables capacitance reduction without changing the planar perimeter of the insulating layer opening. The groove's depth creates additional capacitance reduction capability while the opening perimeter remains unchanged, thus maintaining compatibility with conventional substrates while achieving the desired capacitance reduction.
Data Source
AI summary
An interconnect substrate includes a pad for external connection and an insulating layer, wherein a portion of a lower surface of the pad is covered with the insulating layer, wherein an upper surface of the pad is situated at a lower position than an upper surface of the insulating layer, and wherein a groove whose bottom surface is formed by the insulating layer is formed around the pad in a plan view, and has an opening on an upper surface side of the insulating layer.