Solid Electrolytic Capacitor Adhesive Layer Design
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Solution Overview
Problem
Existing solid electrolytic capacitors face issues with short circuits due to conductive adhesives reaching anode-cathode paths and decreased ESR (Equivalent Series Resistance) caused by gas formation during heat curing, which affects the performance and reliability of the capacitors.
Innovation Solution
A solid electrolytic capacitor design featuring a laminate structure with a conductive adhesive layer surrounded by an insulating adhesive layer, including notched parts to prevent adhesive leakage and allow gas release, thereby preventing shorts and maintaining low ESR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conductive adhesive layer is used to bond capacitor elements, then bonding strength is improved, but the conductive adhesive may reach anode areas and cause short circuits
Solution Approach 1:
The adhesive layer is segmented into two distinct functional layers: an insulating adhesive layer that prevents short circuits, and a conductive adhesive layer that provides bonding strength. This segmentation allows each layer to perform its specific function without interfering with the other, resolving the contradiction between bonding strength and short circuit prevention.
Solution Approach 2:
The insulating adhesive layer acts as an intermediary barrier between the conductive adhesive layer and the anode areas. It mediates the conflict by allowing the conductive adhesive to bond elements while preventing it from reaching and shorting the anode, thus enabling both strong bonding and reliable short circuit prevention.
2Strength
If a conductive adhesive layer is heat cured to strengthen bonding, then bonding strength is improved, but gasification of organic solvent creates cavities that lower ESR
Solution Approach 1:
The harmful gasification process is extracted and isolated to specific notched regions where gas can escape safely. By providing dedicated gas release pathways, the harmful effect of gas formation is removed from the bonding areas, allowing heat curing to proceed without creating ESR-lowering cavities in the adhesive layers.
Solution Approach 2:
The gasification of organic solvent during heat curing, which is normally harmful as it creates cavities, is converted into a beneficial process by directing the gas through notched parts. The gas release paths transform the harmful gasification into a controlled process that prevents cavity formation in the bonding areas while still allowing the adhesive to cure and strengthen.
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
The proposed design effectively prevents short circuits and suppresses the decrease in ESR, enhancing the reliability and performance of solid electrolytic capacitors by ensuring proper adhesive placement and gas management during the manufacturing process.
Implementation Method 1
gasification of an organic solvent during the heat curing of the conductive adhesive
Implementation Method 2
The first layer and the second layer are bonded by an adhesive layer
Data Source
AI summary
A solid electrolytic capacitor that includes an element laminate having a first end face and a second end face, a first external electrode on the first end face, and a second external electrode on the second end face. In the element laminate, a first layer and a second layer are stacked. The first layer has a valve-action metal substrate, a dielectric layer on a surface thereof, and a solid electrolyte layer on the dielectric layer. The second layer contains a metal foil. The first layer and the second layer are bonded by an adhesive layer containing a conductive adhesive layer and an insulating adhesive layer that surrounds an outer perimeter of the conductive adhesive layer. The adhesive layer includes a notched part that extends from the first end face or the second end face to the conductive adhesive layer.