Copper Paste Composition for Uniform Semiconductor Pressure Bonding
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Solution Overview
Problem
Existing bonding compositions struggle to achieve strong and uniform bonding between thin or large-area semiconductor elements during the pressure-bonding process, leading to potential damage and uneven bonding.
Innovation Solution
A copper paste for pressure bonding is developed, comprising two or more copper powders with different shapes and particle sizes, and a solvent, with specific viscosity, mass ratio, and bulkiness index characteristics to ensure strong and uniform bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bonding composition is used to bond thin or large-area semiconductor elements, then the bonding process can be performed, but damage to semiconductor elements and uneven bonding occur
Solution Approach 1:
The invention changes the physical and chemical parameters of the bonding composition by incorporating a solid reducing agent that decomposes at elevated temperatures to generate reducing gas. This parameter change enables sufficient bonding strength while preventing oxidation of copper particles, thereby achieving reliable bonding without damage to thin or large-area semiconductor elements
Solution Approach 2:
The invention uses a composite material system consisting of copper powder, solid reducing agent, and organic solvent. The solid reducing agent (e.g., sugar alcohol, amino alcohol, or carboxylic acid) works synergistically with copper powder to provide both bonding capability and protective reducing atmosphere during the bonding process, eliminating damage and uneven bonding
2Quantity of substance
If the bonding area is increased to accommodate large-area semiconductor elements, then the electrical conduction capability is improved, but uneven bonding occurs more frequently
Solution Approach 1:
The invention changes the chemical environment during bonding by introducing a solid reducing agent that releases reducing gas upon heating. This creates a controlled chemical atmosphere that prevents oxidation and ensures uniform bonding across large areas, maintaining manufacturing precision even as bonding area increases
3Strength
If the pressure-bonding process is applied to thinner semiconductor elements, then the bonding strength is improved, but damage to the semiconductor elements increases
Solution Approach 1:
The solid reducing agent acts as an intermediary substance that decomposes to generate reducing gas during the bonding process. This intermediary creates a protective atmosphere between the bonding interface and oxygen, enabling strong bonding of thin semiconductor elements without causing damage through oxidation or excessive pressure
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 copper paste enables bonding with high strength and uniformity even for thin or large-area semiconductor elements, reducing the risk of damage and ensuring reliable electrical conduction.
Implementation Method 1
C represents a film thickness of a dried coating film formed by drying the coating film in an air atmosphere at 110° C. for 20 minutes
Implementation Method 2
the sintered material is sometimes used in a pressure-bonding process
Data Source
AI summary
Provided is a copper paste for pressure bonding, the copper paste at least containing two or more copper powders having different shapes and/or particle sizes and a solvent. The copper paste has a viscosity of 10 Pa·s or more and 200 Pa·s or less. The ratio of the total mass of the two or more copper powders to the mass of the copper paste, A, is 0.60 or more and less than 0.82. When the index of bulkiness, H, is defined as H=C/(A×B), H is 0.75 or more and 1.00 or less, wherein A is as defined above, B represents the film thickness of a coating film formed by applying the copper paste to a substrate, and C represents the film thickness of a dried coating film formed by drying the coating film in an air atmosphere at 110° C. for 20 minutes.