Tantalum Capacitor Wire Bonding Reduces ESR and ESL
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Solution Overview
Problem
Tantalum capacitors face limitations in increasing capacitance and efficiency due to internal lead frames reducing space and external terminals increasing contact resistance, leading to higher equivalent series resistance (ESR) and equivalent series inductance (ESL).
Innovation Solution
A tantalum capacitor design featuring a simple structure without via holes, incorporating tantalum wires and an adhesive layer connected to anode and cathode lead frames within a molding part, which reduces ESR and ESL by minimizing current path length and optimizing the volume ratio of tantalum material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal lead frames are used to connect anode and cathode, then connection is achieved, but the space occupied by lead frames reduces the volume of tantalum material, limiting capacitance
Solution Approach 1:
The patent removes the internal lead frames from the capacitor structure entirely. Instead, external lead frames are positioned at the bottom surface of the molding part, and tantalum wires extend from the tantalum element to connect to these external lead frames, eliminating the space occupation problem while maintaining connection functionality
Solution Approach 2:
The connection structure is moved from an internal three-dimensional arrangement to an external two-dimensional arrangement at the bottom surface. The lead frames are positioned externally at the bottom surface rather than being embedded internally, changing the spatial dimension of connection and freeing up internal volume for tantalum material
2Ease of manufacture
If terminals are exposed externally without frames, then manufacturing is simplified, but contact resistance increases due to multiple contact materials, increasing ESR and ESL
Solution Approach 1:
The patent combines the functions of multiple separate contact materials into a single integrated tantalum wire connection. The tantalum wire directly connects the tantalum element to the external lead frame, eliminating multiple contact interfaces and reducing contact resistance, while maintaining manufacturing simplicity
Solution Approach 2:
The tantalum wire acts as an intermediary element that bridges the tantalum element and the external lead frame. This single intermediary connection reduces the number of contact interfaces compared to multiple contact materials, thereby reducing cumulative contact resistance while maintaining ease of manufacture
3Reliability
If cathode terminal is positioned on the side of product, then connection is achieved, but welding distance increases, reducing internal volume ratio of tantalum material and decreasing capacitance
Solution Approach 1:
The cathode connection is moved from a side-positioned three-dimensional arrangement to a bottom-surface two-dimensional arrangement. The external lead frames are positioned at the bottom surface of the molding part, shortening the welding distance and increasing the internal volume ratio of tantalum material
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
This design simplifies the manufacturing process, increases capacitance, and achieves low ESR and ESL, while allowing for a more compact and efficient capacitor structure.
Implementation Method 1
forming a manganese dioxide (MnO2) layer, which is an electrolyte, on this tantalum oxide as a dielectric substance, formed by anodic oxidation method
Implementation Method 2
tantalum wires and an adhesive layer on a lower surface of the tantalum capacitor body
Data Source
AI summary
There is provided a tantalum capacitor including: a tantalum capacitor body; a plurality of tantalum wires and an adhesive layer on a lower surface of the tantalum capacitor body; and a molding part enclosing the tantalum capacitor body, wherein the tantalum wire and the adhesive layer are connected to an anode lead frame and a cathode lead frame, respectively.