Thermosetting Resin Prepreg for LED Mounting

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Solution Overview

Problem

Conventional laminates for electronic devices lack adequate heat dissipation properties, high thermal conductivity, and fire retardancy, particularly in high-density LED mounting applications, where they also face issues with drilling performance and heat resistance during lead-free reflow soldering.

Innovation Solution

A prepreg with a thermosetting resin composition containing 80 to 200 volume parts of inorganic filler per 100 volume parts of resin, comprising gibbsite aluminum hydroxide, boehmite, and aluminum oxide particles with specific particle diameters and ratios, which imparts excellent thermal conductivity, heat resistance, and fire retardancy, while maintaining drilling performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional laminates are used for high-density LED mounting, then electronic devices can be compact and lightweight, but heat dissipation properties are insufficient

Engineering Contradiction:
Improveheat dissipation propertiesVSAvoidthermal management reliability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent uses a composite resin composition containing multiple types of inorganic fillers (aluminum hydroxide, aluminum oxide, silicon oxide, boron nitride) with different thermal conductivities and functions. This composite structure enables simultaneous achievement of heat dissipation, fire retardancy, and mechanical strength, resolving the contradiction between compact design and thermal management reliability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes the particle size distribution (D50 values ranging from 0.5 to 10 μm) and volumetric ratios of different inorganic fillers to balance heat dissipation efficiency with mechanical drilling performance. By controlling the D50 of aluminum hydroxide at 2-15 μm and aluminum oxide at 0.5-1.5 μm, the patent achieves both thermal conductivity and acceptable drilling characteristics.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If lead-free reflow soldering is used for mounting, then environmental impact is reduced, but blistering occurs due to high temperature requirements

Engineering Contradiction:
Improveenvironmental impactVSAvoidblistering resistance
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent modifies the thermal stability parameters of the resin composition by incorporating fire retardants (aluminum hydroxide at 20-60 vol%, aluminum oxide at 5-30 vol%) and optimizing the base resin selection. This enables the laminate to withstand lead-free reflow soldering temperatures (240-260°C) without blistering, while maintaining environmental compatibility.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the potentially harmful high temperature exposure during lead-free soldering into a beneficial demonstration of the material's enhanced thermal stability. The fire retardant inorganic fillers not only provide fire safety but also act as thermal barriers that prevent blistering during high-temperature soldering processes.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If inorganic fillers are added to improve fire retardancy, then fire safety is enhanced, but drilling performance deteriorates

Engineering Contradiction:
Improvefire retardancyVSAvoiddrilling performance
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent optimizes the particle size parameters of inorganic fillers, specifically controlling the D50 of aluminum hydroxide at 2-15 μm and aluminum oxide at 0.5-1.5 μm. This size optimization ensures sufficient fire retardancy while minimizing negative impacts on drilling performance by reducing filler aggregation and improving resin matrix continuity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates local quality variations in the resin composition by using a multi-component filler system where different fillers serve different functions. Aluminum hydroxide provides fire retardancy, aluminum oxide enhances thermal stability, silicon oxide improves flow characteristics, and boron nitride contributes to thermal conductivity. This local functional differentiation allows the material to achieve fire safety without uniformly compromising drilling performance.

Inventive Principle:
Principle #3Local quality

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 high thermal conductivity, heat resistance, and fire retardancy, reducing drill wear and preventing blistering during solder reflow, thereby enhancing the reliability of printed wiring boards for LED applications.

Implementation Method 1

the inorganic filler comprises (A) gibbsite aluminum hydroxide particles having an average particle diameter (D50) of 2 to 15 μm

Methodology Applied
Scientific EffectEndothermic reaction: Endothermic Reaction

Implementation Method 2

the inorganic filler comprises (C) aluminum oxide particles having an average particle diameter (D50) of 1.5 μm or smaller

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2502956B1Prepreg, laminate, metal-foil-clad laminate, circuit board, and circuit board for LED mounting
Publication Date: 2017.09.20 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP2502956B1 patent drawingFigure 1A~1C
  • EP2502956B1 patent drawingFigure 2
  • EP2502956B1 patent drawing

AI summary

Disclosed is a prepreg obtained by impregnating a woven fabric base with a thermosetting resin composition, wherein the thermosetting resin composition contains 80 to 200 volume parts of an inorganic filler per 100 volume parts of a thermosetting resin, and the inorganic filler contains (A) gibbsite aluminum hydroxide particles having an average particle diameter (D50) of 2 to 15 µm, (B) at least one inorganic component selected from the group consisting of boehmite particles having an average particle diameter (D50) of 2 to 15 µm and inorganic particles that have an average particle diameter (D50) of 2 to 15 µm and that contain crystal water having a release initiation temperature of 400°C or higher or contain no crystal water, and (C) aluminum oxide particles having an average particle diameter (D50) of 1.5 µm or smaller, the compounded ratio (volume ratio) of the gibbsite aluminum hydroxide particles (A), the at least one inorganic component (B) selected from the group consisting of the boehmite particles and the inorganic particles, and the aluminum oxide particles (C) being 1: 0.1 to 2.5 : 0.1 to 1.