Pressure-Bonding Composition for Void-Resistant Conductor Joining
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Solution Overview
Problem
Existing bonding methods for semiconductor devices face challenges such as void formation, non-uniform thickness, and reduced reliability due to the use of low heat-resistance materials, and they require additional facilities and steps for pressure bonding, which increases costs and reduces efficiency.
Innovation Solution
A composition for pressure bonding comprising a metal powder and a solid reducing agent, with a compressibility range of 10% to 90%, is used to form a conductive film between conductors, allowing for high bonding strength and stability even with varying conductor sizes and arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If non-pressure bonding method is used, then equipment complexity is reduced, but bonding strength and reliability deteriorate due to void formation and non-uniform thickness
Solution Approach 1:
The invention changes the physical-chemical parameters of the bonding material by using a paste with specific compressibility (10-90%) and incorporating a solid reducing agent. This allows the paste to be applied in a fluid state and then transformed during sintering, achieving reliable bonding without requiring complex pressure bonding equipment.
Solution Approach 2:
The paste is applied to the conductor surface in advance while maintaining fluidity, allowing the conductor arrangement to be finalized before sintering. The solid reducing agent is incorporated beforehand to enable in-situ reduction during sintering, eliminating the need for separate reduction steps or complex pressure bonding facilities.
2Strength
If pressure bonding method is used, then bonding strength improves, but device complexity and production cost increase due to additional facilities and steps
Solution Approach 1:
The invention replaces the need for complex pressure bonding mechanical systems with a chemical approach. The solid reducing agent undergoes in-situ reduction during sintering to form metallic bonds, substituting mechanical pressure application with chemical bonding mechanisms that achieve similar or superior bonding strength without complex equipment.
Solution Approach 2:
The paste formulation enables self-bonding during the sintering process. The solid reducing agent automatically reduces the metal oxides in the paste to form conductive bonds between conductors, eliminating the need for external pressure application systems or additional bonding steps.
3Productivity
If paste is applied and sintered without pressure, then production efficiency improves, but manufacturing precision deteriorates due to void formation and non-uniform thickness
Solution Approach 1:
The invention optimizes the paste parameters including compressibility (10-90%), particle size distribution, and solid reducing agent content to achieve uniform film formation during drying and sintering. These parameter optimizations ensure consistent bonding thickness without requiring pressure control, maintaining both productivity and manufacturing precision.
4Ease of manufacture
If low heat-resistance bonding material is used, then ease of manufacture improves, but reliability deteriorates due to heat accumulation in compact power modules
Solution Approach 1:
The invention uses a composite paste formulation containing metal particles, metal oxide particles, and solid reducing agent in specific ratios. This composite structure provides both ease of manufacture (as a printable paste) and high heat resistance (through the sintered metallic bonds), resolving the contradiction between manufacturability and thermal reliability in compact power modules.
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 achieves high bonding strength and stability between conductors, reducing the impact of conductor thickness variations and enabling reliable electrical connections, while also improving production efficiency and reducing costs.
Implementation Method 1
a composition for pressure bonding, including a metal powder and a solid reducing agent
Implementation Method 2
a bonded structure of conductors, and a method for producing the bonded structure... sintering the metal powder of the stack
Data Source
AI summary
A composition for pressure bonding contains a metal powder and a solid reducing agent and has a compressibility of 10% to 90%, the compressibility being expressed by a relationship formula using the thickness A of a dried coating film formed by drying the composition in an air atmosphere at 110° C. under atmospheric pressure for 20 minutes and the thickness B of a sintered body formed by treating the dried coating film in a nitrogen atmosphere at 280° C. under a pressure of 6 MPa for 20 minutes. The solid reducing agent may be BIS-TRIS. Also provided is a bonded structure of conductors in which a bonding portion via which two conductors are bonded together is formed by treating, under pressure, the two conductors and a coating film formed of the composition for pressure bonding provided therebetween.