Pressure Bonding Composition for Void-Free Conductor Joining
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Solution Overview
Problem
Existing pressure bonding methods for semiconductor devices face challenges in achieving high bonding strength and reliability due to void formation and non-uniform thickness issues, especially when using low heat-resistance materials, and require additional facilities and steps for applying pressure, which increase costs and reduce efficiency.
Innovation Solution
A composition for pressure bonding comprising metal powder and a solid reducing agent is applied between conductors, sintered under controlled conditions to form a conductive film, providing a compressible layer that stabilizes bonding regardless of conductor thickness variations, achieving high adhesion and bonding strength without the need for new facilities or complex production steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If non-pressure bonding method is used with paste containing solvent, then bonding process is simplified, but voids form in bonding portion and paste leaks causing nonuniform thickness
Solution Approach 1:
The invention changes the physical state of the bonding material from a solvent-based paste to a solid composition. This parameter change eliminates the harmful effects of solvent evaporation (void formation, leakage) while maintaining ease of manufacture. The solid composition is applied as a paste or powder and then sintered to form the bonding portion, achieving both process simplicity and thickness uniformity.
2Strength
If pressure bonding is applied to achieve high bonding strength, then bonding strength improves, but additional facilities and production steps are required
Solution Approach 1:
The invention applies preliminary action by pre-forming the bonding material into a solid composition with controlled properties before the bonding process. The composition is prepared in advance with specific particle size distribution, density, and composition ratios that enable it to achieve high bonding strength through sintering without requiring complex pressure bonding facilities. The preliminary preparation of the solid composition eliminates the need for additional pressure application equipment.
3Strength
If solid reducing agent is used in bonding composition, then bonding strength and adhesion improve, but composition formulation becomes more complex
Solution Approach 1:
The invention uses composite materials by formulating a bonding composition that combines metal powder (copper, silver, or their alloys) with a solid reducing agent in specific ratios. This composite composition leverages the synergistic effects of the metal powder (providing conductivity and strength) and the solid reducing agent (promoting sintering and adhesion). The composition may also include organic compounds containing heteroatoms (N, O, S) that facilitate controlled decomposition and sintering. This composite approach achieves high bonding strength while managing formulation complexity through systematic design.
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 enables stable, high bonding strength between conductors, even with large or multiple semiconductor devices, by forming a dense sintered structure that maintains electrical conduction reliability and withstands temperature exposure, while reducing production costs and complexity.
Implementation Method 1
a solid reducing agent contained in the composition for pressure bonding
Implementation Method 2
sintered under controlled conditions to form a conductive film
Data Source
AI summary
A composition for pressure bonding of the present invention 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. It is also preferable that the solid reducing agent is 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.