Circuit Board Grain Size Design for Heat Dissipation and Warpage

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Solution Overview

Problem

Circuit boards with thin members lack high heat dissipation properties, leading to warpage and reliability issues due to heat generated by electronic components, which can cause detachment and cracking of the supporting substrate.

Innovation Solution

A circuit board design featuring a circuit member with copper as the principal component, having a first region with a larger average grain size for thermal conductivity and a second region with a smaller average grain size for high stiffness, located closer to the mounting surface, to reduce warpage and enhance heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the circuit member is made thin to reduce size, then the device compactness is improved, but the heat dissipation properties deteriorate

Engineering Contradiction:
Improvecircuit member thicknessVSAvoidheat dissipation
Core Design Contradiction:
Volume of moving objectVSLoss of energy

Solution Approach 1:

The circuit member employs a dual-region grain size structure: a first region with larger grain size for high thermal conductivity near the supporting substrate, and a second region with smaller grain size for high stiffness near the mounting surface. This local differentiation allows the thin circuit member to simultaneously achieve effective heat dissipation and adequate mechanical strength.

Inventive Principle:
Principle #3Local quality

2Volume of moving object

If the circuit member is made thin to reduce size, then the device compactness is improved, but the warpage resistance deteriorates

Engineering Contradiction:
Improvecircuit member thicknessVSAvoidwarpage
Core Design Contradiction:
Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The second region adjacent to the mounting surface is designed with smaller grain size to provide high stiffness and low warpage characteristics. This localized structural optimization ensures that the thin circuit member maintains dimensional stability and resists warpage under thermal stress despite reduced overall thickness.

Inventive Principle:
Principle #3Local quality

3Loss of energy

If the grain size is increased to improve thermal conductivity, then the heat dissipation is improved, but the stiffness deteriorates

Engineering Contradiction:
Improveheat dissipationVSAvoidstiffness
Core Design Contradiction:
Loss of energyVSStrength

Solution Approach 1:

The circuit member is divided into two functional regions with different grain sizes: the first region has larger grain size optimized for thermal conductivity to facilitate heat dissipation, while the second region has smaller grain size optimized for stiffness to prevent warpage. This spatial differentiation resolves the contradiction between thermal performance and mechanical strength.

Inventive Principle:
Principle #3Local quality

4Volume of moving object

If the circuit member is made thin to reduce size, then the device compactness is improved, but the reliability deteriorates

Engineering Contradiction:
Improvecircuit member thicknessVSAvoidreliability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The dual-region grain size structure ensures that the thin circuit member maintains both adequate stiffness (second region with smaller grains) and thermal conductivity (first region with larger grains), preventing warpage-related failures such as detachment and cracking, thereby maintaining high reliability despite reduced thickness.

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 design effectively reduces warpage and improves heat dissipation properties, resulting in a highly reliable circuit board with improved durability and extended lifespan.

Implementation Method 1

a second region located closer to the mounting surface side than the first region, the second region having a second average grain size smaller than the first average grain size

Methodology Applied
Scientific EffectGrain boundary strengthening: Grain Boundary Strengthening

Implementation Method 2

The first region has a high average grain size and good thermal conductivity, compared with the second region, thereby enabling the efficient dissipation of heat transferred from the second region

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2579696B1Circuit board and electronic device using the same
Publication Date: 2018.12.05 KYOCERA CORP
  • EP2579696B1 patent drawingFigure 1(a)~1(b)
  • EP2579696B1 patent drawingFigure 2(a)~2(c)
  • EP2579696B1 patent drawingFigure 3(a)~3(c)

AI summary

Provided are a circuit board and an electronic device using the same, wherein little distortion of a circuit member is caused due to the heat generated by the operation of an electronic component which is mounted on the circuit member and the circuit board has reliability in high heat dissipation performance. A circuit board (10) is configured such that a circuit member (2) which is made primarily of copper is provided on one principal surface of a supporting substrate (1) and the upper surface of the circuit member (2) serves as a mounting surface for electronic components, wherein the circuit member (2) is provided with a first region having a first average grain size and a second region located closer to the mounting surface side than the first region and having a second average grain size smaller than the first grain size.