Phosphorus Active Ester Resin for Low Dielectric High Tg PCBs

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Solution Overview

Problem

Existing epoxy resin compositions used in printed wiring boards lack sufficient heat resistance and flame retardancy while maintaining low dielectric constants and tangents, especially in halogen-free formulations.

Innovation Solution

An active ester resin containing a phosphorus atom is developed, with a specific molecular structure featuring aromatic nuclei connected through an alicyclic hydrocarbon group and an arylene dicarbonyloxy group, and substituted with specific structural sites that enhance heat resistance and flame retardancy without compromising dielectric properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If an active ester compound with a dicyclopentadiene skeleton is used as a curing agent, then the dielectric constant and dielectric tangent are reduced, but the cured product lacks sufficient heat resistance and flame retardancy

Engineering Contradiction:

Improvedielectric constant and dielectric tangentVSAvoidheat resistance and flame retardancy

Core Design Contradiction:

Quantity of substanceVSTemperature

Solution Approach 1:

The patent modifies the molecular structure parameters of the active ester compound by replacing the dicyclopentadiene skeleton with an aromatic hydrocarbon structure containing phosphorus atoms. This structural parameter change simultaneously achieves low dielectric properties (εr=3.6, tanδ=0.009) and high heat resistance (Tg=182°C), resolving the contradiction between dielectric performance and thermal stability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite molecular structure combining aromatic nuclei, alicyclic hydrocarbon groups, and phosphorus-containing functional groups within the active ester resin. This composite structure integrates the beneficial properties of each component: aromatic structures provide thermal stability, alicyclic groups contribute to low dielectric constants, and phosphorus atoms deliver flame retardancy, thereby resolving the contradiction between opposing requirements.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a phenol novolak-type active ester resin is used, then the curing properties are good, but the dielectric constant and dielectric tangent are not sufficiently low

Engineering Contradiction:

Improvecuring propertiesVSAvoiddielectric constant and dielectric tangent

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent changes the chemical composition parameters by introducing phosphorus-containing aromatic structures with specific molecular weights and functional group ratios. The resulting active ester resin maintains excellent curing properties through its phenolic hydroxyl groups while achieving unusually low dielectric constants (εr=3.6) and tangents (tanδ=0.009), resolving the contradiction between curing performance and dielectric properties.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If halogen-based flame retardants are excluded, then environmental safety is improved, but flame retardancy and heat resistance become insufficient

Engineering Contradiction:

Improveenvironmental safetyVSAvoidflame retardancy and heat resistance

Core Design Contradiction:

Object-affected harmful factorsVSTemperature

Solution Approach 1:

The patent converts the traditionally harmful approach of using halogen-based flame retardants into a beneficial solution by employing phosphorus-containing aromatic structures. These phosphorus compounds provide effective flame retardancy through a halogen-free mechanism, achieving UL94 V-0 rating while maintaining environmental safety and simultaneously providing heat resistance (Tg=182°C), thus resolving the contradiction between environmental safety and flame retardancy.

Inventive Principle:

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

4Length of moving object

If the wiring pitch is narrowed to achieve high density wiring, then the miniaturization is improved, but the heat resistance requirements become more stringent

Engineering Contradiction:

Improvewiring pitchVSAvoidheat resistance

Core Design Contradiction:

Length of moving objectVSTemperature

Solution Approach 1:

The patent achieves high wiring pitch density while meeting stringent heat resistance requirements by developing an active ester resin with optimized molecular parameters. The resulting cured product exhibits Tg=182°C and excellent solder resistance, enabling high-density wiring implementations (fine-pitch PCBs) to withstand the thermal stresses of modern soldering processes without compromising structural integrity.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9963544B2Active ester resin containing phosphorus atom, epoxy resin composition and cured product thereof, prepreg, circuit board, and build-up film

Publication Date: 2018.05.08 DIC CORP

AI summary

The present invention provides an active ester resin containing a phosphorus atom capable of providing a cured product having all of flame retardancy, heat resistance, and dielectric characteristics, an epoxy resin composition containing the same as a curing agent, a cured product thereof, a prepreg, a circuit board, and a build-up film. The active ester resin containing a phosphorus atom has Structure (I) in which a structural unit (α) in which a plurality of aromatic nuclei (X) are connected through an alicyclic hydrocarbon group is connected with another structural unit (α) through an arylene dicarbonyloxy group, and, at least one of the aromatic nuclei (X) present in the resin has a structural site (Y) represented by any one of the following Structural Formulas (y1) to (y4) as a substituent on the aromatic nucleus.