Tantalum Capacitor Stacked Elements and Screening for ESR Reduction
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Solution Overview
Problem
There is a need for improved packing density, electronic performance, and reliability in solid tantalum capacitors, particularly in multi-array package (MAP) designs, and an efficient method for screening these capacitors to select the most reliable ones for applications in high-frequency and robust environments.
Innovation Solution
The development of tantalum capacitors with a conductive polymer cathode and efficient package construction, including the stacking of multiple anode elements, along with a screening process that involves applying a voltage exceeding the capacitor's rating and elevated temperature to measure DC leakage current, ensuring high reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple capacitor elements are stacked in a multi-array package to increase packing density, then volumetric efficiency is improved, but device complexity increases
Solution Approach 1:
The capacitor is divided into multiple discrete capacitor elements (first, second, and third capacitor elements) that are stacked vertically within a single package. Each element has its own anode, cathode, and dielectric layer, allowing independent fabrication and assembly. This segmentation enables higher packing density while maintaining manageable complexity through modular construction.
Solution Approach 2:
Multiple capacitor elements are nested within a single molded package body, with the first capacitor element positioned at a first level, the second capacitor element at a second level, and the third capacitor element at a third level. The elements are arranged vertically one above another, similar to nested dolls, maximizing the use of vertical space within the package volume.
2Reliability
If a screening process is applied to test capacitor reliability, then reliability is improved, but productivity decreases
Solution Approach 1:
A screening process is performed on the capacitors before they are shipped to customers. The screening includes applying a voltage exceeding the voltage rating of the capacitor and measuring the DC leakage current at elevated temperature. This preliminary action identifies and eliminates unreliable capacitors before field deployment, ensuring high reliability in the final product.
Solution Approach 2:
The screening process replaces extensive field testing and failure analysis with a controlled laboratory test. By measuring DC leakage current under elevated temperature and over-voltage conditions, the screening process efficiently identifies potential reliability issues without requiring long-term field operation or complex failure analysis equipment.
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 solution results in capacitors with higher volumetric efficiency, lower equivalent series resistance (ESR) and inductance (ESL), leading to superior high-frequency performance and enhanced reliability, as demonstrated by the screening process that effectively identifies and enhances the robustness of the capacitors.
Implementation Method 1
measuring the DC leakage current of the capacitor
Data Source
AI summary
Disclosed are tantalum capacitors having enhanced volumetric efficiency, effective series resistance, effective series inductance, and high frequency performance when compared to existing tantalum capacitors. Also disclosed is a screening process for tantalum capacitors to enhance reliability.