Leadless Ceramic Capacitor Stack Using Polymer Conductive Adhesive
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Solution Overview
Problem
Conventional multilayer ceramic capacitors face challenges with high defect rates due to rapid heating during welding, microcracks from high-temperature TLPS paste, and insufficient toughness to resist mechanical stress, limiting their application in high-capacitance and miniaturization demands.
Innovation Solution
A leadless stack using polymer conductive adhesive with 75%∼85% metal powder and 15%∼25% viscose for bonding and electroplating, allowing for low-temperature assembly and electroplating strengthening, enhancing mechanical strength and toughness without high-temperature heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional welding process is used to assemble multilayer ceramic capacitors, then assembly strength is achieved, but rapid heating causes cracks and damages to the capacitors
Solution Approach 1:
The patent changes the bonding mechanism from thermal welding to low-temperature conductive adhesive bonding. The conductive adhesive forms electrical connections without requiring high-temperature heating, thereby avoiding thermal damage to the ceramic capacitors while still achieving sufficient assembly strength.
Solution Approach 2:
The patent replaces the thermal field (welding heat) with a chemical field (conductive adhesive bonding). The conductive adhesive uses chemical adhesion and electrical conductivity to achieve both mechanical strength and electrical connection, eliminating the need for high-temperature thermal processing.
2Strength
If high-temperature TLPS paste is used for stacking, then support strength is improved, but microcracks form due to phase change and volume change
Solution Approach 1:
The patent changes the bonding temperature from high-temperature (above 300°C) to low-temperature processing. The conductive adhesive cures at lower temperatures without undergoing phase changes that cause volume expansion and contraction, thereby preventing microcrack formation while maintaining support strength.
Solution Approach 2:
The patent uses a composite conductive adhesive material that combines polymer matrix with conductive fillers (such as metal particles or carbon materials). This composite structure provides both mechanical support strength and electrical conductivity without the harmful effects of high-temperature TLPS paste phase changes.
3Adaptability or versatility
If metal leads or lead frames are used for stacking, then conductive channels and support strength are provided, but the structure is complex and requires high-temperature welding
Solution Approach 1:
The patent merges the functions of mechanical support and electrical conduction into a single conductive adhesive layer. Instead of using separate metal leads for support and separate welding joints for conduction, the conductive adhesive simultaneously provides both functions, greatly simplifying the stacking structure.
Solution Approach 2:
The conductive adhesive serves multiple functions: it provides mechanical bonding strength, establishes electrical conductive channels, and enables low-temperature assembly. This multi-functional material replaces the complex multi-component metal lead and welding system.
4Productivity
If rapid heating rate is used during welding, then production speed is improved, but defect rate increases due to capacitor heating and damage
Solution Approach 1:
The patent changes the assembly temperature parameter from high-temperature welding to low-temperature conductive adhesive bonding. This allows for rapid assembly without the risk of thermal damage, simultaneously improving productivity and reducing defect rates.
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 provides a reliable, low-temperature assembly process with improved mechanical strength and reduced defect rates, effectively resisting mechanical stress and vibration, while enabling uniform electroplating and increased capacitance through series combinations of ceramic capacitors.
Implementation Method 1
the external electrodes of a plurality of multilayer ceramic capacitors use a polymer conductive adhesive as the bonding material to form a adhesive interface that provides support strength and conductive channels
Implementation Method 2
a first plating layer and a second plating layer of an electroplating strengthening layer are formed by nickel plating and tin plating in sequence
Data Source
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AI summary
The present invention provides a leadless stacked ceramic capacitor. the capacitor body are respectively provided with internal electrode terminals. The part forms an electrical connection with the external electrodes, and a plurality of multilayer ceramic capacitors are vertically stacked, and the two adjacent external electrodes are cured to form an adhesive interface by polymer conductive adhesive, and the polymer conductive adhesive includes 75%-85% metal powder and 15%-25% viscose provide support strength and conductive channels.