Wiring Substrate Electrode Layout for Stable Stray Capacitance
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Solution Overview
Problem
High-precision wiring substrates face issues with varying stray capacitance between electrodes formed between the same layers due to undulations, which affect electrical characteristics and yield.
Innovation Solution
A wiring substrate design with insulating layers and electrodes where the first electrode is thicker than the second electrode, positioned such that its lower surface is below and upper surface is above the second electrode's, preventing stray capacitance variation even with undulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-precision wiring substrates are manufactured with electrodes formed between the same layers, then manufacturing precision is improved, but stray capacitance varies due to undulations affecting electrical characteristics
Solution Approach 1:
The patent changes the geometric parameter of the first electrode by making it protrude in the stacking direction relative to the second electrode. This parameter change creates an overlapping area between the first electrode and the second electrode, which stabilizes the stray capacitance against variations caused by undulations, thus resolving the contradiction between manufacturing precision and electrical characteristic stability.
2Device complexity
If electrodes are formed close to each other between the same layers to reduce substrate size, then device complexity is reduced, but stray capacitance variation increases when undulations occur
Solution Approach 1:
The patent introduces a dimensional change by making the first electrode protrude in the stacking direction (thickness direction) rather than keeping both electrodes in the same plane. This creates an overlapping volume between the electrodes, which stabilizes the stray capacitance against undulation-induced variations, allowing electrodes to be placed closer together without compromising capacitance stability.
3Reliability
If the first electrode is made thicker and positioned to protrude in the stacking direction, then stray capacitance is stabilized against undulations, but device complexity increases
Solution Approach 1:
The patent applies local quality by making only the first electrode protrude in the stacking direction while keeping the second electrode in its original position. This localized structural modification creates the necessary overlapping area for capacitance stabilization without requiring complex changes to the overall electrode structure or additional components.
Data Source
AI summary
A wiring substrate that is provided enables stray capacitance between a first electrode and a second electrode to be prevented from varying when an undulation occurs in the wiring substrate. Insulating layers are stacked. A first electrode and a second electrode are formed between the same layers at an interval. The thickness of the first electrode is more than the thickness of the second electrode. The lower main surface of the first electrode is located at a position lower than the lower main surface of the second electrode, and the upper main surface of the first electrode is located at a position higher than the upper main surface of the second electrode when seen through in a direction perpendicular to a stacking direction of the insulating layers.