Multilayer Heat-Conductive Sheet Anchor Effect Adhesion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing heat-conductive sheets face challenges in achieving optimal adhesion between the tack-free layer and the heat-conductive layer, leading to interfacial fracture and poor workability during assembly and rework of electronic components, while methods to reduce adhesiveness often compromise heat conductivity and flexibility.
Innovation Solution
A multilayer heat-conductive sheet is developed with a heat-conductive layer and a tack-free layer, where the tack-free layer includes a thermoplastic resin with a glass transition temperature of 60° C. or higher and an inorganic filler with a median diameter of at least 0.5 μm, forming concaves and convexes for enhanced adhesion through an anchor effect, and the heat-conductive layer contains a binder resin with a specific glass transition temperature range, ensuring strong adhesion without compromising flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a heat-conductive sheet is made with high adhesiveness for good workability during assembly, then the sheet adheres well to electronic components and heat sinks, but the electronic component cannot be easily separated from the heat dissipating component
Solution Approach 1:
The heat-conductive sheet is divided into two distinct layers: a first layer with high adhesiveness for assembly workability, and a second layer with low adhesiveness for easy separation. This segmentation allows each layer to fulfill different functional requirements that cannot be satisfied by a single uniform adhesive layer.
Solution Approach 2:
Different regions of the heat-conductive sheet (first layer vs. second layer) are given different adhesive properties. The first layer contacting the electronic component has high adhesiveness, while the second layer has low adhesiveness, creating local quality differences that resolve the contradiction between assembly ease and separation ease.
2Ease of repair
If a non-adhesive tack-free layer is added to reduce surface adhesion for reworkability, then the sheet can be peeled more easily, but the flexibility and heat-conductivity of the sheet deteriorate
Solution Approach 1:
The adhesive properties of the second layer are controlled by adjusting specific parameters: using a thermoplastic resin with glass transition temperature of 60°C or higher, incorporating inorganic filler with median diameter of at least 0.5 μm, controlling thickness between 3-15 μm, and maintaining Bekk smoothness between 20-300 seconds. These parameter changes enable low adhesiveness while preserving flexibility and heat-conductivity.
Solution Approach 2:
The second layer is formulated as a composite material combining thermoplastic resin, inorganic filler (such as aluminum hydroxide, aluminum nitride, or alumina), and optionally a plasticizer. This composite structure provides the desired low adhesion properties while maintaining the mechanical flexibility and thermal conductivity required for reliable heat dissipation.
3Ease of repair
If ultraviolet irradiation is used to reduce adhesiveness of one surface, then the sheet achieves differential adhesiveness, but the layer responsible for heat-conductivity deteriorates
Solution Approach 1:
Instead of modifying the heat-conductive layer through ultraviolet irradiation (which deteriorates it), the invention extracts the adhesive control function to a separate second layer. This second layer is specifically designed with low adhesiveness through material composition rather than surface treatment, preserving the integrity and heat-conductivity of the first layer.
4Ease of repair
If a tack-free layer with high glass transition temperature resin is used to reduce tackiness, then the surface adhesion is reduced, but the adhesion with the heat-conductive layer becomes poor causing interfacial fracture
Solution Approach 1:
The glass transition temperature of the thermoplastic resin in the second layer is carefully controlled to be 60°C or higher (with upper limit of 150°C or lower), and the Bekk smoothness is controlled between 20-300 seconds. These parameter changes optimize the balance between surface tack reduction and interfacial adhesion strength, preventing both excessive tack and interfacial fracture.
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 enhances adhesion between the tack-free and heat-conductive layers, improving workability and reworkability by preventing interfacial fracture and maintaining heat conductivity, while allowing for successful peeling without interlayer separation.
Implementation Method 1
forming concaves and convexes for enhanced adhesion through an anchor effect
Implementation Method 2
the tack-free layer includes a thermoplastic resin having a glass transition temperature of 60° C. or higher
Implementation Method 3
a heat-conductive layer and a tack-free layer
Data Source
AI summary
Peeling due to interfacial fracture between a tack-free layer 11 and a heat-conductive layer is prevented. In the tack-free layer, an inorganic filler having a median diameter of 0.5 μM or more is contained in a thermoplastic resin having a glass transition temperature of 60° C. or higher to form concaves and convexes on an adhesive surface. Then, the heat-conductive layer being in contact with the adhesive surface is disposed. The adhesion between the tack-free layer and the heat-conductive layer is strengthened by an anchor effect caused by the concaves and convexes of the adhesive surface, without strengthening the adhesion of the surface opposite to the adhesive surface.