Tantalum Capacitor Frame Terminal Layout for Drop Impact Reliability
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Solution Overview
Problem
Tantalum capacitors are prone to chip detachment due to separation of internal lead frames and molded portions when subjected to drops and impacts, leading to reliability issues.
Innovation Solution
A tantalum capacitor design featuring a tantalum body with a tantalum wire, a molded portion surrounding the body, an anode lead frame connected to the wire, a cathode lead frame spaced apart from the anode, and a frame terminal protruding from the molded portion to distribute stress effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional tantalum capacitor structure with internal lead frame is used, then the capacitor can be manufactured with standard processes, but the lead frame and molded portion separate under drop impact causing chip detachment
Solution Approach 1:
The patent removes the internal lead frame structure from the capacitor design. Instead of using a lead frame embedded within the molded portion, the invention uses external lead frames that are positioned outside the molded portion, thereby eliminating the separation issue between internal lead frame and molded portion under impact conditions.
Solution Approach 2:
The patent introduces a cushioning structure between the capacitor chip and the external environment. The molded portion is designed to provide mechanical support and absorption of impact forces before they can reach the chip, preventing detachment by cushioning the impact in advance.
2Strength
If the lead frame is embedded within the molded portion, then the structure appears compact, but stress concentration occurs during impacts leading to detachment
Solution Approach 1:
The patent transitions from a two-dimensional embedded lead frame structure to a three-dimensional configuration where lead frames extend externally. This dimensional change allows the lead frames to distribute stress over a larger volume and provide better mechanical support without increasing the footprint area of the capacitor.
Solution Approach 2:
The patent employs a composite structure combining the molded portion material with the lead frame material. The molded portion provides mechanical support and stress distribution, while the lead frames provide electrical connection and additional structural reinforcement, creating a composite system that resists stress concentration effectively.
3Reliability
If the capacitor uses a standard molded portion design, then manufacturing is simplified, but the chip remains vulnerable to impact forces
Solution Approach 1:
The patent implements preliminary protective action by designing the molded portion to extend and surround the capacitor chip in advance, creating a protective cage structure before any impact occurs. This preliminary structural arrangement ensures that the chip is mechanically supported and protected from impact forces during normal operation and under stress conditions.
Data Source
AI summary
A tantalum capacitor includes a tantalum body including a tantalum element including tantalum powder, and a tantalum wire passing through at least a portion of the tantalum element in a first direction, a molded portion having fifth and sixth surfaces opposing each other in the first direction, third and fourth surfaces opposing each other in a second direction, first and second surfaces opposing each other in a third direction, the molded portion formed to surround the tantalum body, an anode lead frame connected to the tantalum wire, a cathode lead frame spaced apart from the anode lead frame, the cathode lead frame connected to the tantalum body, and a frame terminal disposed on the anode lead frame and the cathode lead frame to be spaced apart from the second surface of the molded portion.