Sintering Joining Material for Microdevice Bonding
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Solution Overview
Problem
Conventional methods for joining microdevices using solder or copper pillars require high pressure, leading to issues like Kirkendall voids, reflow failure, and impedance mismatch, and result in decreased yield and reliability due to the need for specialized equipment and individual pressure application.
Innovation Solution
A method involving a laminated body with a metal pillar, an electrode pad, and a joining material containing metal particles and an organic compound, where the joining material satisfies the condition (M1−M2)/M1×100≥1.0, allowing sintering at a predetermined temperature without high pressure, using sub-micro and micro copper particles with specific size and shape distributions, and thermally decomposable resins to reduce thermal expansion-induced damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high pressure is applied during joining, then joining strength is improved, but device complexity and production cost increase due to need for special pressurization equipment
Solution Approach 1:
The patent replaces the mechanical pressurization system with a thermal field system. By applying heat to induce phase change in the joining material (from solid to liquid and back to solid), the joining process achieves strong bonding without requiring complex high-pressure mechanical equipment. The thermal energy substitutes for mechanical pressure as the primary driving force for joining.
Solution Approach 2:
The patent utilizes phase transitions of the joining material to achieve joining without high pressure. The joining material undergoes melting phase change at elevated temperature, allowing it to flow and fill gaps between components, then solidifies upon cooling to form a strong joint. This phase transition mechanism eliminates the need for continuous high-pressure application during the joining process.
2Strength
If high pressure is applied during joining, then joining strength is improved, but production yield decreases due to damage to members being joined
Solution Approach 1:
By replacing mechanical pressurization with thermal processing, the patent eliminates the damaging effects of high pressure on delicate microdevice components. The thermal field gently heats the joining material and surrounding components without applying destructive mechanical forces, thereby preserving component integrity and reducing defects that would reduce production yield.
Solution Approach 2:
The phase transition-based joining process allows the joining material to flow and bond components in a controlled manner during melting, then solidify without applying damaging pressure. This gentle thermal process avoids mechanical damage to fragile members being joined, thereby improving production yield while maintaining joining strength.
3Strength
If high pressure is applied during joining, then joining strength is improved, but process complexity increases due to need for individual pressure application
Solution Approach 1:
The patent replaces the complex individual pressurization process with a uniform thermal processing step. By applying heat uniformly across the joining area, the joining material undergoes phase change and bonds all components simultaneously without requiring individual pressure application to each joint, significantly simplifying the manufacturing process.
Solution Approach 2:
The phase transition mechanism enables simultaneous joining of multiple components through uniform heating. As the joining material melts and solidifies uniformly across the entire assembly, all joints are formed concurrently without requiring sequential or individual pressure application, making the process easier to manufacture and scale.
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
This approach prevents joining failure even at reduced pressures, simplifies the joining process, reduces equipment complexity, and enhances production yield by minimizing damage to the joined members and maintaining reliable connections.
Implementation Method 1
heating the laminated body to sinter the joining material at a predetermined sintering temperature
Implementation Method 2
thermally decomposable resins to reduce thermal expansion-induced damage
Data Source
AI summary
Provided is a method for producing a joined body, the method including a first step of preparing a laminated body which includes a first member having a metal pillar provided on a surface thereof, a second member having an electrode pad provided on a surface thereof, and a joining material provided between the metal pillar and the electrode pad and containing metal particles and an organic compound, and a second step of heating the laminated body to sinter the joining material at a predetermined sintering temperature, in which the joining material satisfies the condition of the following Formula (I):(M1−M2)/M1×100≥1.0 (I)[in Formula (I), M1 represents a mass of the joining material when a temperature of the joining material reaches the sintering temperature in the second step, and M2 represents a non-volatile content in the joining material.]