Insulating Circuit Board Bond Interface for Adhesion Without Peeling
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Solution Overview
Problem
Existing insulating circuit boards face challenges with adhesion between the insulating resin layer and the metal part, leading to potential peeling issues during use, and large surface roughness of the metal plate can reduce insulation properties.
Innovation Solution
A bonded body with an uneven bonded interface between the insulating resin member and the metal part, featuring a protrusion and recess structure, and an overhang rate of 7% or more, ensuring sufficient engagement and adhesion between the components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the surface roughness of the metal plate is increased to improve adhesion, then adhesion between the insulating resin layer and the circuit layer is improved, but insulation properties (insulating withstand voltage) are reduced due to concentration of electric charges
Solution Approach 1:
The invention changes the surface parameters by controlling the root mean square deviation (Rq) and kurtosis (Rku, Sku) to specific ranges. By setting Rq to 0.20-0.90 μm and kurtosis to 2.75-6.00, the invention optimizes the balance between adhesion and insulation properties, resolving the contradiction between improving adhesion through roughness while maintaining insulation performance.
Solution Approach 2:
The invention applies local quality by creating an uneven shape with protrusions and recesses at the bonded interface rather than uniform roughness. This localized structural modification provides mechanical interlocking for adhesion while controlling charge concentration through the specific geometric characteristics (kurtosis and Rq values) of the protrusions and recesses.
2Ease of manufacture
If the bonded interface is made flat to simplify manufacturing, then manufacturing complexity is reduced, but adhesion between the insulating resin layer and the metal part is insufficient causing peeling
Solution Approach 1:
The invention applies curvature by creating an uneven bonded interface with protrusions and recesses instead of a flat surface. This curved/uneven geometry provides mechanical interlocking that significantly improves adhesion strength while preventing peeling, resolving the contradiction between manufacturing simplicity and adhesion performance.
3Strength
If the protrusion tips are made sharp to increase engagement, then adhesion is improved, but insulation properties are reduced due to electric field concentration at sharp points
Solution Approach 1:
The invention resolves this contradiction by changing the geometric parameters of the protrusions. By controlling the root mean square deviation (Rq) to 0.20-0.90 μm and kurtosis (Rku, Sku) to 2.75-6.00, the protrusion tips achieve sufficient sharpness for mechanical engagement while avoiding excessive sharpness that would concentrate electric fields and compromise insulation properties.
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
A bonded body of the present invention has a structure in which an insulating resin member made of an insulating resin and a metal part made of a metal are bonded. In the bonded body, a bonded interface between the insulating resin member and the metal part has an uneven shape including a protrusion in which the metal part protrudes toward an insulating resin member side and a recess in which the metal part retracts from the insulating resin member side, at least one of a kurtosis Rku of contour curve at the bonded interface of the metal part and a kurtosis Sku of contour surface at the bonded interface of the metal part is in a range of 2.75 or more and 6.00 or less, and an overhang rate that indicates a length ratio of regions overlapping in a lamination direction in a direction along the bonded interface is 7% or more.