Hard Spherical Carbon Conductive Adhesive for Low Resistance Bonding
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Solution Overview
Problem
Conductive adhesives using carbon particles face challenges with high resistance values compared to metal particles like Ag and Cu, and suffer from low anchor effect and reliability issues under mechanical and thermal impacts due to the destruction of carbon particles during pressing.
Innovation Solution
A conductive resin composition incorporating hard spherical carbon with a particle strength of 200 MPa or more and fine carbon particles or pieces, which are coated onto the surface of spherical base carbon particles, is used to increase the number of contacting points and areas, providing a reliable bonding structure resistant to mechanical and thermal impacts by incorporating these particles into the conductors during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbon particles are used as conductive particles in conductive adhesive, then cost is reduced compared to metal particles, but resistance value increases
Solution Approach 1:
The patent uses composite carbon particles consisting of a spherical base carbon particle (diameter 3-10 μm) coated with fine carbon particles (diameter 0.1-1 μm). This composite structure combines the advantages of both large and small particles: the spherical base provides structural integrity and resistance to destruction, while the fine carbon coating increases the number of contacting points and enhances conductivity. The result is a conductive adhesive with lower resistance values while maintaining cost-effectiveness compared to metal particles.
2Reliability
If carbon particles are pressed to increase contacting points, then connection resistance decreases, but carbon particles are destroyed and anchor effect is lost
Solution Approach 1:
The carbon particle is segmented into two functional parts: a spherical base carbon particle that provides mechanical strength and resistance to destruction, and a coating of fine carbon particles that provides numerous contacting points for electrical conduction. This segmentation allows each part to fulfill its specific function without compromising the other, solving the contradiction between particle strength and contacting points.
Solution Approach 2:
Different regions of the carbon particle structure have different properties optimized for their specific functions. The inner spherical base has high mechanical strength to resist destruction during pressing, while the outer fine carbon coating has high surface area and numerous contacting points to ensure low connection resistance. This local quality differentiation resolves the contradiction between particle durability and electrical conductivity.
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 achieves low connection resistance and high conduction reliability, ensuring durable electrical connections even under stress conditions, such as those encountered with piezoelectric elements, by enhancing the anchor effect and maintaining conductivity and wear resistance.
Implementation Method 1
press-contacting the objects with each other by an appropriate pressure
Implementation Method 2
by curing the matrix resin, the electronic component is mechanically bonded to the substrate
Implementation Method 3
the electronic component is electrically connected to the land of the substrate by the conductive particles contained in the matrix resin
Data Source
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AI summary
To provide a conductive resin composition with which high conduction reliability can be ensured, a method for manufacturing, using the composition, an electronic component having high bonding reliability, a bonding method and a bonding structure by which objects to be bonded can be bonded to each other with certainty, and a highly reliable electronic component having the bonding structure. A conductive resin composition which includes (a) a curable resin and (b) hard spherical carbon formed by coating the surface of a spherical base carbon particle with fine carbon particles and/or hard spherical carbon formed by coating the surface of a spherical base carbon particle with pitch-derived fine carbon pieces, is used. The conductive resin composition is suppled to a space between areas of at least two works respectively having the areas to be electrically connected to each other, and the conductive resin composition is cured while applying a pressure between the areas.