Conductive Paste for Multilayer Board Hole Filling
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Solution Overview
Problem
Conductive pastes face challenges in achieving high conductivity and long-term reliability while maintaining suitable viscosity and storage stability, particularly when using silver-coated copper alloy powders, which do not improve pot life or conductivity in conventional formulations.
Innovation Solution
A conductive paste composition including dimer acid-modified epoxy resin, low melting metal powders, high melting silver-coated copper alloy powders, hydroxy group-containing aromatic curing agents, and polycarboxylic acid flux, which are formulated to provide excellent conductivity and long-term reliability, suitable for filling holes in boards and forming multilayer boards with improved connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver powder or silver-coated copper powder is used as metal powder in conductive paste, then good conductivity is obtained, but the cost increases and long-term reliability is insufficient
Solution Approach 1:
The patent uses composite metal powder consisting of copper core with silver coating, combining the high conductivity of silver with the lower cost and good ductility of copper. This composite structure achieves both cost reduction and maintained conductivity while improving long-term reliability through optimized material properties
Solution Approach 2:
The patent optimizes the silver coating thickness and copper core composition parameters to achieve the best balance between conductivity, cost, and reliability. By controlling the silver layer thickness and copper purity, the paste achieves reliable performance without excessive silver content
2Quantity of substance
If silver-coated copper alloy powder is used to reduce cost, then storage stability improves, but pot life is not prolonged and conductivity is not improved
Solution Approach 1:
The patent introduces organic additives and flux components as intermediaries that protect the silver-coated copper alloy powder from oxidation and degradation during storage. These additives form protective films on the metal surface, preventing direct exposure to oxygen and moisture, thereby extending pot life
Solution Approach 2:
The patent modifies the chemical composition parameters of the paste by adding specific ratios of flux, resin, and curing agents that create a stable environment for the metal powder. These compositional changes prevent premature reactions and extend the usable life of the paste
3Reliability
If metal powders are merely brought into contact with each other or metal powder is merely brought into contact with conductive layer end surface, then manufacturing is simple, but conductivity is insufficient and connection reliability is poor
Solution Approach 1:
The patent segments the metal powder into different size fractions and uses a distribution of particle sizes. This allows smaller particles to fill gaps between larger particles, creating more contact points and improving conductivity without requiring complex external connections
Solution Approach 2:
The patent creates a composite structure where metal powders are embedded in a matrix of flux and resin that facilitates bonding. This composite approach enables reliable electrical connection through the combined action of metal-to-metal contact and metal-to-substrate bonding
4Duration of action of moving object
If conventional conductive paste formulation is used, then manufacturing is straightforward, but viscosity is not suitable for hole filling and pot life is short
Solution Approach 1:
The patent systematically adjusts the formulation parameters including resin type, flux composition, and metal powder particle size distribution to achieve optimal viscosity for hole filling. By controlling these parameters within specific ranges, the paste maintains appropriate flow characteristics and extended pot life
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 conductive paste achieves remarkable conductivity and long-term reliability, with improved connection reliability between conductive layers and metal particles, and extended pot life, making it suitable for electronic board applications and precise pattern formation.
Implementation Method 1
the paste is heated under certain conditions... metal powders are fused and metallized
Implementation Method 2
The paste is obtained by mixing a conductive filler with a flux, a curing agent and a thermosetting resin, and the resin is cured
Data Source
AI summary
A conductive paste having a viscosity suitable for filling a hole of a board, long pot life, and excellent conductivity and long-term reliability of a cured product, and a multilayer board using the same are provided.A conductive paste comprising with respect to (A) 100 parts by mass of dimer acid-modified epoxy resin, (B) from 200 to 1900 parts by mass of high melting metal powder containing silver-coated copper alloy powder and having a melting point of 800° C. or higher, (C) from 400 to 2200 parts by mass of silver-coated copper alloy powder having a melting point of 800° C. or higher, (D) from 1.0 to 20.0 parts by mass of curing agent containing a hydroxy group-containing aromatic compound, and (E) from 5.0 to 100.0 parts by mass of a flux containing polycarboxylic acid, is used as the present invention.