EMI Shielding Sheet Modulus Tuning for Edge Coverage and Embedding
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Solution Overview
Problem
Existing electromagnetic wave shielding sheets for electronic component-mounting substrates face challenges in providing high embedding properties, ground connectivity, and Pressure Cooker Test (PCT) resistance while maintaining flexibility and preventing edge cracking, especially due to acute angles formed by half dicing, which degrades the shielding layer's quality and connectivity.
Innovation Solution
An electromagnetic wave shielding sheet with a conductive layer that includes a binder resin and conductive filler, having a Young's modulus of 10 to 700 MPa at 23°C and 5 to 85 MPa at 80°C, and a glass transition temperature of −15°C to 30°C, which is thermally pressed to form a layer that covers step parts and edges, ensuring high embedding and edge covering properties and PCT resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the hardness level of the film of the electromagnetic wave shielding sheet is improved to prevent edge parts from being broken, then edge covering properties are improved, but the embedding properties into concave parts are degraded
Solution Approach 1:
The patent applies parameter changes by controlling the Young's modulus of the conductive layer within a specific range (10 to 700 MPa at 23°C, 5 to 85 MPa at 80°C) and the glass transition temperature (−15°C to 30°C). This optimized parameter range enables the material to have sufficient hardness to prevent edge breakage while maintaining softness for proper embedding into concave parts, thus resolving the contradiction between edge covering properties and embedding properties.
2Adaptability or versatility
If the electromagnetic wave shielding sheet is made flexible to fill grooves between electronic components, then embedding properties are improved, but PCT resistance is degraded
Solution Approach 1:
The patent resolves this contradiction by optimizing the glass transition temperature of the conductive layer to be between −15°C and 30°C, and controlling the curing degree to be 60% to 99%. This parameter optimization enables the material to exhibit flexibility at operating temperatures for proper groove filling while maintaining sufficient crosslinking density through curing to achieve PCT resistance for long-term weather durability.
3Ease of manufacture
If the electromagnetic wave shielding sheet is thermally pressed on acute angle edges, then the shielding layer is formed, but the sheet is easily broken at edge parts
Solution Approach 1:
The patent resolves this contradiction by controlling the Young's modulus of the conductive layer to be within 10 to 700 MPa at 23°C and 5 to 85 MPa at 80°C. This optimized modulus range provides the right balance between flexibility for conforming to acute angle edges during thermal pressing and sufficient strength to prevent breakage, enabling both easy manufacturing and edge integrity.
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 provides a reliable electromagnetic wave shielding layer with improved embedding properties, ground connectivity, and PCT resistance, enhancing the reliability of component-mounting substrates and electronic devices by effectively covering concave-convex surfaces and maintaining structural integrity.
Implementation Method 1
an electromagnetic wave shielding sheet before thermal pressing for forming an electromagnetic wave shielding layer
Data Source
AI summary
An electromagnetic wave shielding sheet according to the present embodiments is an electromagnetic wave shielding sheet for forming an electromagnetic wave shielding layer used for a component-mounting substrate including a substrate, an electronic component and an electromagnetic wave shielding layer, in which the electromagnetic wave shielding sheet includes at least one of a conductive layer before thermal pressing of the electromagnetic wave reflection layer and a conductive layer before thermal pressing of the electromagnetic wave absorption layer, the conductive layer before thermal pressing of the electromagnetic wave reflection layer includes a binder resin and a conductive filler, and the conductive layer before thermal pressing of the electromagnetic wave absorption layer includes a binder resin and an electromagnetic wave absorption filler. The Young's modulus of the conductive layer at 23° C. is set to 10 to 700 MPa.