Embedded Semiconductor Capacitor Structure for PCB Integration
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Solution Overview
Problem
Existing semiconductor-based capacitors are surface-mounted, taking up valuable surface area and are not suitable for embedding within circuit boards due to their coplanar terminals and vulnerability to mechanical and environmental stress, which complicates reliable connections.
Innovation Solution
A semiconductor-based capacitor design with distinct coplanar upper terminals and a lower terminal, featuring a ratio of maximum width to thickness greater than 80:1, allowing embedding within a substrate with reduced surface area and improved reliability through laser-drilled connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If semiconductor-based capacitors are surface-mounted with coplanar terminals, then they are easy to manufacture and assemble, but they take up increased surface area and are not suitable for embedding within circuit boards
Solution Approach 1:
The patent transitions from surface mounting to embedding the capacitor within the circuit board substrate. The capacitor structure is designed with terminals extending in opposite directions (top and bottom surfaces) rather than coplanar arrangement, enabling three-dimensional integration within the PCB thickness, thus reducing the surface footprint while maintaining electrical connectivity.
2Reliability
If through-hole mounting is used to ensure reliability under mechanical stress, then connection reliability is improved, but the drilling process compromises the integrity of thin-film capacitors by causing physical damage
Solution Approach 1:
The capacitor is embedded within recessed openings in the circuit board substrate, nesting the fragile thin-film capacitor structure within the more robust PCB material. This protective embedding shields the capacitor from mechanical stress and environmental factors while maintaining reliable electrical connections through conductive pathways formed in the substrate.
Solution Approach 2:
Conductive adhesive or solder material acts as an intermediary between the capacitor terminals and the circuit board substrate. This intermediate layer provides mechanical bonding and electrical connectivity without requiring direct drilling through the capacitor, thus protecting the capacitor integrity while ensuring reliable connections.
3Ease of manufacture
If coplanar terminals are used for flip-chip mounting, then manufacturing is simplified, but the increased surface area requirement prevents embedding within circuit boards
Solution Approach 1:
The capacitor design employs terminals that extend in the thickness direction of the substrate rather than arranged coplanarly on the surface. This vertical terminal configuration enables the capacitor to be embedded within the circuit board while maintaining simplified manufacturing processes similar to conventional capacitors.
4Area of stationary object
If the capacitor is designed with high width-to-thickness ratio for embedding, then surface area is reduced for embedding, but the capacitor structure becomes more vulnerable to mechanical stress
Solution Approach 1:
The thin-profile capacitor with high width-to-thickness ratio is nested within recessed openings in the circuit board substrate. This embedding provides mechanical support and protection from external stresses while maintaining the low surface area footprint necessary for high-density circuit board integration.
Solution Approach 2:
The recessed opening structure and surrounding substrate material act as a cushioning mechanism that absorbs and distributes mechanical stress before it reaches the fragile capacitor body, protecting the high aspect ratio structure from warping or cracking under mechanical load.
Data Source
AI summary
A semiconductor-based capacitor can include a substrate including a semiconductor material, an oxide layer formed over the substrate, a conductive layer formed over at least a portion of the oxide layer, a plurality of distinct coplanar upper terminals, and a lower terminal. The upper terminals and the lower terminal can be exposed along the top and bottom surfaces of the substrate, respectively, for embedding the capacitor in a substrate such as a circuit board. The semiconductor-based capacitor can be sufficiently miniaturized to be embeddable within a circuit board while providing superior capacitance values without compromising the integrity of the capacitor. For example, each of the upper terminals can have a maximum width and a thickness normal to the maximum width, and a ratio of the width to the thickness can be greater than about 80:1 to prevent physical damage to the capacitor from warping or cracking.