Embedded Capacitor Design for Wiring Board Step Formation
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Solution Overview
Problem
The integration of capacitors into wiring boards is hindered by issues such as increased process complexity, restricted component layout, and long wiring distances due to the need for separate capacitor mounting, which can lead to faulty conduction and step formation during resin filler application.
Innovation Solution
A capacitor design featuring laminated dielectric layers with inner electrode layers and dummy electrode layers, where almost all outer peripheral surfaces of the inner electrode layers are exposed, and a manufacturing method that includes forming inner and dielectric patterns on ceramic sheets, allowing for a thicker capacitor end portion to alleviate step issues and prevent resin filler contact with outer terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional capacitor with thinner end portions is used, then the capacitor structure is simpler, but steps are formed at the end portions causing resin filler to enter the reverse surface side and contact outer terminals resulting in faulty conduction
Solution Approach 1:
The invention addresses the step formation problem by exposing the outer peripheral surfaces of inner electrode layers from between ceramic layers in the vertical dimension. This dimensional change allows the capacitor end portions to maintain a substantially constant thickness, preventing resin filler from entering the reverse surface side and contacting outer terminals, thereby eliminating faulty conduction without complicating the overall capacitor structure
Solution Approach 2:
The invention extracts the problematic end portions with steps from the capacitor structure by exposing only the necessary outer peripheral surfaces of inner electrode layers. This selective extraction removes the source of the problem (thinner end portions) while maintaining the functional integrity of the capacitor, preventing resin filler intrusion without requiring additional structural elements
2Ease of manufacture
If capacitors are mounted separately on the wiring board, then the capacitor can be easily replaced, but the number of processes increases and the wiring distance becomes long resulting in large wiring resistance and inductance
Solution Approach 1:
The invention merges the capacitor with the wiring board by incorporating it directly into the board structure during the manufacturing process. The capacitor is formed within the wiring board substrate, eliminating the need for separate mounting processes while maintaining the electrical functionality. This integration reduces the number of manufacturing steps and minimizes wiring distance between the capacitor and semiconductor chip, thereby reducing wiring resistance and inductance
3Productivity
If the capacitor is incorporated in the wiring board, then the wiring distance is reduced, but the resin filler may contact outer terminals causing faulty conduction
Solution Approach 1:
The invention uses dimensional change by exposing outer peripheral surfaces of inner electrode layers from between ceramic layers, creating a substantially constant thickness profile at the capacitor end portions. This prevents resin filler from entering the reverse surface side and contacting outer terminals during the incorporation process, thereby maintaining reliability while achieving short wiring distances for improved productivity
Data Source
AI summary
A capacitor comprising: a plurality of laminated dielectric layers; a plurality of inner electrode layers each disposed between mutually adjacent ones of the dielectric layers; and dummy electrode layers respectively disposed between the dielectric layers, disposed on sides closer to outer peripheral sides of the dielectric layers than to the inner electrode layers and disposed apart from the inner electrode layers.