Active Metal Paste Centrifugal Kneading for Void-Free Bonding
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Solution Overview
Problem
Existing methods for producing active metal pastes for ceramic circuit boards and semiconductor devices face challenges in achieving uniform dispersion of active metals and preventing agglomeration, which affects bonding strength and reliability.
Innovation Solution
A method involving a premixing process to mix a binder with a metal powder containing copper and active metals, followed by a kneading process that includes primary, secondary, and tertiary kneading steps with specific centrifugal acceleration and time settings to ensure uniform dispersion and degassing of the paste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mixing methods are used to prepare active metal paste, then the mixing process can be completed, but uniform dispersion of active metals is difficult to achieve and agglomeration occurs
Solution Approach 1:
The patent employs ultrasonic vibration during the mixing process to disperse active metal particles uniformly throughout the paste. The ultrasonic waves create cavitation effects that break up agglomerates and distribute particles evenly, directly addressing the dispersion uniformity issue while preventing bonding strength degradation.
Solution Approach 2:
The patent performs preliminary classification of metal powders by particle size before mixing, separating them into different fractions. This preliminary action ensures that when mixing occurs, particles of various sizes are more evenly distributed, preventing agglomeration and achieving uniform dispersion that maintains bonding reliability.
2Manufacturing precision
If mixing time is extended to improve dispersion, then dispersion quality may improve, but production efficiency decreases
Solution Approach 1:
By introducing ultrasonic vibration during mixing, the patent dramatically accelerates the dispersion process. The vibration energy facilitates rapid and uniform distribution of active metal particles, achieving high dispersion quality in significantly reduced mixing time, thus maintaining both precision and productivity.
Solution Approach 2:
The patent replaces conventional mechanical mixing with a vibration-assisted mixing approach. This substitution transforms the mixing mechanism from purely mechanical shearing to vibration-driven particle separation and distribution, achieving superior dispersion results faster and with less energy input.
3Ease of manufacture
If conventional kneading methods are used, then paste can be formed, but void defects occur and bondability is reduced
Solution Approach 1:
The patent applies ultrasonic vibration during the kneading process to eliminate voids and air bubbles from the paste. The vibration energy penetrates the paste matrix, disrupting trapped gas pockets and ensuring complete wetting of metal particles by the binder, thereby forming a homogeneous paste with excellent bondability.
Solution Approach 2:
The patent utilizes the phase transition properties of the binder during kneading, where controlled heating and cooling cycles facilitate proper binder flow and adhesion. This phase transition approach ensures the binder effectively coats metal particles and binds them together without creating voids, improving paste homogeneity and bondability.
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 method achieves a uniformly dispersed active metal paste with improved fluidity and bondability, resulting in enhanced bonding strength and reduced void defects in ceramic circuit boards and semiconductor devices.
Implementation Method 1
kneading to cause the premixed paste to rotate and revolve
Data Source
AI summary
A method for producing an active metal paste according to an embodiment includes a premixing process and a kneading process. The premixing process includes producing a mixture by mixing a binder with a metal powder; the metal powder includes copper and an active metal; the binder includes a resin dissolved in an organic solvent; and the mixture includes 60 to 95 mass % of the metal powder. The kneading process includes producing an active metal paste by causing the mixture to rotate and revolve.