Induction-Sintered Conductive Paste for Low-Temperature Bonding
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Solution Overview
Problem
Current conductive adhesive technologies face challenges with high-pressure deformation, weak bonding strength, and high temperature requirements, as well as reduced electrical conductivity due to oxide layers and non-uniform coating in device bonding processes.
Innovation Solution
A conductive paste is developed with a mixture of metal particles and a magnetic heating element, dispersed in an organic material, which is applied to a substrate and sintered using induction heating to form a conductive film, allowing for low-temperature bonding and high-speed electrical conductivity with improved sintering density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pressurized bonding method is used with silver paste, then bonding strength is very high, but deformation occurs due to pressure applied to the device chip and entire module
Solution Approach 1:
The patent replaces the mechanical pressurized bonding system with an induction heating-based bonding system. Instead of applying mechanical pressure to achieve bonding, the invention uses magnetic heating elements that generate heat through induction heating to melt and bond the conductive paste, thereby eliminating pressure-induced deformation while maintaining high bonding strength.
Solution Approach 2:
The patent changes the bonding parameter from mechanical pressure to thermal energy. By controlling the induction heating parameters (frequency, power, time) and the melting point of the conductive paste material, the bonding process achieves high strength without the harmful mechanical pressure that causes deformation.
2Productivity
If non-pressurized method with small silver particles is used, then sintering speed is ensured, but bonding strength is weak and high temperature is required causing heat damage
Solution Approach 1:
The patent replaces conventional thermal conduction heating with induction heating technology. The magnetic heating elements dispersed in the conductive paste generate heat directly through electromagnetic induction, enabling rapid heating and sintering without requiring high external temperatures, thus achieving both high sintering speed and high bonding strength without heat damage to surrounding components.
Solution Approach 2:
The patent introduces magnetic heating elements locally within the conductive paste formulation. These elements are dispersed throughout the paste and generate heat locally through induction heating, creating localized high-temperature zones that enable rapid sintering of the conductive paste without heating the entire substrate or surrounding components to high temperatures.
3Productivity
If induction heating is performed on conductive film with coated metal particles, then sintering is achieved, but oxide layer remains on surface reducing electrical conductivity
Solution Approach 1:
The patent uses a composite conductive paste formulation consisting of conductive metal particles (such as silver or copper) combined with magnetic heating elements (such as ferrite or iron oxide particles). This composite structure enables induction heating to melt and densify the paste while the conductive metal particles form a continuous conductive network that maintains low sheet resistance and high electrical conductivity after sintering.
Solution Approach 2:
The patent optimizes the particle size distribution, composition ratio, and sintering parameters of the conductive paste to achieve complete densification without oxide layer formation. By controlling the sintering temperature, time, and atmosphere parameters in conjunction with the specific paste formulation, the process achieves full densification while preventing oxidation, thereby maintaining high electrical conductivity.
4Reliability
If coating process is performed on metal particles, then conductivity is improved, but uniform coating layer formation is difficult reducing contact force
Solution Approach 1:
The patent extracts and eliminates the complex multi-layer coating process from the manufacturing workflow. Instead of coating metal particles with multiple metal layers to improve conductivity, the invention uses a simplified formulation of conductive metal particles combined with magnetic heating elements, relying on the intrinsic conductivity of the metal particles and the densification effect of induction heating to achieve low sheet resistance without requiring uniform coating layers.
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 low-temperature bonding with high-speed processing, enhanced electrical conductivity, and reduced material costs due to the selective heating of the magnetic heating element, while minimizing thermal damage and deformation risks.
Implementation Method 1
A conductive paste is developed with a mixture of metal particles and a magnetic heating element, dispersed in an organic material, which is applied to a substrate and sintered using induction heating to form a conductive film
Implementation Method 2
when induction heating is performed over the conductive film, the metal particles inside are magnetized to generate heat
Data Source
AI summary
The present invention comprises the steps of: applying, on a substrate, a conductive paste including metal particles that are dispersed in an organic material and have a first particle diameter, and a magnetic heating element that has a second particle diameter; and selectively sintering the applied conductive paste by induction heating to form a conductive film, wherein the magnetic heating element may be contained in an amount of 10-50 wt% with respect to the metal particles. Therefore, a conductive adhesive layer can be selectively formed by performing the sintering through induction heating. In addition, by adding a small amount of the magnetic heating element to conductive metal powder having a low melting point, low-temperature bonding and electric conductivity can be simultaneously attained.