Coreless Substrate Prepreg Resin Composition for Warpage Control

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Solution Overview

Problem

Coreless substrates face challenges with warpage due to thermal expansion differences between semiconductor elements and printed wiring boards, leading to connection failures, and existing solutions either increase warpage or compromise bonding strength with metal circuits.

Innovation Solution

A prepreg comprising a thermosetting resin composition containing dicyandiamide, an adduct of tertiary phosphine and quinones, an amine compound with primary amino groups, and a maleimide compound with N-substituted maleimide groups, which improves heat resistance, low thermal expansion, and bonding strength with metal circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the support (core substrate) is removed to create a coreless substrate for thinning, then the board thickness is reduced and wiring density is improved, but the rigidity is lowered and warpage increases

Engineering Contradiction:

Improveboard thicknessVSAvoidrigidity

Core Design Contradiction:

Length of moving objectVSStrength

Solution Approach 1:

The patent changes the chemical composition parameters of the resin system by using a specific combination of epoxy resin, phenolic resin, and cyanate resin in controlled ratios. This parameter optimization allows the thin coreless substrate to achieve sufficient rigidity and warpage control without requiring a thick core substrate, thus resolving the contradiction between thinning and maintaining strength.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite resin system combining multiple resin types (epoxy, phenolic, cyanate) with glass fiber reinforcement. This composite material approach provides enhanced mechanical properties and dimensional stability in the thin coreless substrate, allowing it to maintain rigidity despite the removal of the core substrate.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the coefficient of thermal expansion of the printed wiring board is reduced to match the semiconductor element, then warpage is suppressed, but the bonding strength with metal circuits may be compromised

Engineering Contradiction:

Improvewarpage controlVSAvoidbonding strength with metal circuit

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent optimizes the resin composition parameters to achieve a balanced coefficient of thermal expansion that closely matches semiconductor elements while maintaining adequate bonding strength. The specific ratios of epoxy, phenolic, and cyanate resins are tuned to provide both low thermal expansion and sufficient adhesion to metal circuits.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The composite resin system with glass fiber reinforcement provides both dimensional stability (low thermal expansion) and mechanical strength (bonding to metal circuits). The synergistic combination of resin types and glass fiber creates a material that simultaneously achieves warpage control and bonding strength.

Inventive Principle:

Principle #40Composite materials

3Quantity of substance

If insulating resin containing no glass cloth is laminated on both sides of prepreg to reduce thermal expansion, then thermal expansion coefficient increases, but this method tends to increase warpage

Engineering Contradiction:

Improveglass cloth contentVSAvoidwarpage

Core Design Contradiction:

Quantity of substanceVSShape

Solution Approach 1:

The patent maintains glass cloth in the prepreg layer to provide structural reinforcement and dimensional stability. The optimized resin system works synergistically with the glass cloth to achieve low thermal expansion without requiring the removal of glass cloth, thus preventing warpage while still reducing overall thermal expansion coefficient.

Inventive Principle:

Principle #40Composite materials

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 prepreg provides a coreless substrate with enhanced flexural elastic modulus, excellent rigidity, and improved desmear resistance while maintaining high bonding strength with metal circuits, effectively addressing warpage and thermal expansion issues.

Implementation Method 1

a thermosetting resin composition containing (a) dicyandiamide, (b) an adduct of a tertiary phosphine and quinones

Methodology Applied

Scientific EffectThermosetting:

Implementation Method 2

the coefficient of thermal expansion of a prepreg obtained by impregnating a glass cloth with a resin composition follows the Scapery Equation

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS11581212B2Prepreg for coreless substrate, coreless substrate and semiconductor package

Publication Date: 2023.02.14 RESONAC CORP

AI summary

The present invention provides a prepreg for a coreless substrate and a coreless substrate and a semiconductor package using the prepreg, which can satisfy heat resistance, low thermal expansion, and bonding strength with a metal circuit at a level required for the coreless substrate. Specifically, the prepreg for a coreless substrate contains a thermosetting resin composition containing (a) dicyandiamide, (b) an adduct of a tertiary phosphine and quinones, (c) an amine compound having at least two primary amino groups, and (d) a maleimide compound having at least two primary amino groups having at least two N-substituted maleimide groups. Instead of (c) the amine compound having at least two primary amino groups and (d) the maleimide compound, having at least two N-substituted maleimide groups, (X) an amino-modified polyimide resin obtained by reacting them may be used.