Multi-Layer Underfill Sheet for Electrode Gap Infiltration
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Solution Overview
Problem
Conventional mold underfill encapsulant materials fail to adequately infiltrate the narrow gaps between electrodes in electronic components, leading to insufficient encapsulation and increased voids, especially in high-density integrated circuits used for IoT and automated driving applications.
Innovation Solution
A multi-layer sheet with an outermost layer composed of a resin composition having a specific tan δ (loss tangent) value and containing fillers with controlled particle sizes, along with a secondary layer that conforms to thermal expansion and modulus requirements, ensuring efficient infiltration and reduced warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mold underfill encapsulant materials are used, then the encapsulation process can be completed, but the infiltrability between narrow electrodes is insufficient
Solution Approach 1:
The patent changes the physical and chemical parameters of the resin composition, specifically controlling the tan δ (loss tangent) to be 3 or more at 125°C, and adjusting the glass transition temperature to 80°C or more. These parameter changes enable the material to achieve both high infiltrability into narrow electrode gaps and complete encapsulation, resolving the contradiction between encapsulation quality and infiltrability.
Solution Approach 2:
The patent uses a composite resin composition containing specific components: epoxy resin, phenolic resin, silica filler, and coupling agent. This composite material structure provides both the flow characteristics needed for infiltrability and the mechanical properties needed for encapsulation, simultaneously achieving infiltration into narrow gaps and complete encapsulation.
2Manufacturing precision
If resin composition with low viscosity is used to improve infiltrability, then infiltration into gaps is enhanced, but elastic force for pushing material from behind is insufficient
Solution Approach 1:
The patent optimizes the tan δ (loss tangent) parameter to be 3 or more at 125°C, which represents the balance between elastic and viscous properties. This parameter change ensures the material has sufficient elasticity to push from behind while maintaining low enough viscosity to infiltrate narrow gaps, resolving the contradiction between infiltrability and elastic force.
3Manufacturing precision
If multi-layer sheet with specific tan δ is used, then infiltrability is improved, but the complexity of material specification increases
Solution Approach 1:
The patent establishes specific numerical ranges for key parameters (tan δ ≥ 3 at 125°C, glass transition temperature ≥ 80°C) that directly correlate with infiltrability performance. By focusing on these critical parameters, the patent simplifies material selection and quality control while ensuring high infiltrability, reducing the perceived complexity of material specifications.
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 multi-layer sheet provides superior infiltrability and encapsulation performance with reduced warpage, resulting in high-quality electronic component mounting substrates with enhanced heat and moisture resistance.
Implementation Method 1
the infiltration of conventional mold underfill encapsulant materials between electrodes has been insufficient
Implementation Method 2
The tan δ (loss tangent) represents the proportion of the elastic properties and the viscous properties in a resin composition
Data Source
AI summary
[Problem] To provide a multi-layer sheet for mold underfill encapsulation, which exhibits good infiltrability between electrodes. [Solution] In order to solve the aforementioned problem, the present invention provides a multi-layer sheet for mold underfill encapsulation, which is characterized by having provided as an outermost layer thereof an (A) layer that comprises a resin composition having a local maximum loss tangent (tan δ) value of 3 or more at a measurement temperature of 125° C. for a measurement time of 0-100 seconds.