Aggregate Substrate Warpage Suppression via Interlayer

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Solution Overview

Problem

Conventional varistor production methods result in warpage of aggregate substrates due to differences in contraction between varistor parts and heat dissipation parts during firing, which affects heat dissipation efficiency and device performance.

Innovation Solution

Incorporating a heat dissipation layer sandwiched between varistor parts, ensuring it is in contact with both parts during the lamination and firing process to maintain substrate planarity and enhance heat dissipation efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a heat dissipation part is added to the varistor structure, then heat dissipation efficiency is improved, but warpage occurs during firing due to contraction differences

Engineering Contradiction:

Improveheat dissipation efficiencyVSAvoidsubstrate planarity

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

An intermediary layer (first or second layer) is introduced between the varistor element layer and the heat dissipation part. This intermediary layer acts as a buffer that compensates for contraction differences during firing, preventing warpage while allowing the heat dissipation part to perform its thermal management function effectively.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a composite structure consisting of multiple layers with different material properties: the varistor element layer, the intermediary layer, and the heat dissipation part. Each layer is designed with specific characteristics to fulfill its function, and their combination resolves the contradiction between heat dissipation performance and dimensional stability during manufacturing.

Inventive Principle:

Principle #40Composite materials

2Reliability

If multiple layers are laminated to form aggregate substrate, then varistor functionality is improved, but production complexity increases

Engineering Contradiction:

Improvevaristor functionalityVSAvoidproduction process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The varistor structure is segmented into distinct functional layers: the varistor element layer, the intermediary layer, and the heat dissipation part. This segmentation allows each layer to be optimized independently for its specific function while simplifying the overall production process through modular assembly and standardized manufacturing steps.

Inventive Principle:

Principle #1Segmentation

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

This configuration effectively suppresses warpage and improves heat dissipation efficiency, leading to the production of varistors with enhanced thermal management and reliability.

Implementation Method 1

a heat dissipation layer having a fifth principal face and a sixth principal face facing each other, wherein the fifth principal face of the heat dissipation layer is in contact with the second principal face of the first varistor part and wherein the sixth principal face of the heat dissipation layer is in contact with the fourth principal face of the second varistor part

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

The aggregate substrate is obtained by laminating green sheets to become the varistor parts, electrode patterns to become the internal electrodes, etc. to form a multilayer green body, and firing this multilayer green body. When this multilayer green body is fired, there is difference between contraction caused by firing of the varistor parts and contraction caused by sintering of the heat dissipation part

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS8125307B2Aggregate substrate, production method of aggregate substrate, and varistor

Publication Date: 2012.02.28 TDK CORP

AI summary

An aggregate substrate has a first varistor part, a second varistor part, and a heat dissipation layer. The first varistor part includes a first varistor element layer to exhibit nonlinear voltage-current characteristics, and a plurality of first internal electrodes juxtaposed in the first varistor element layer. The second varistor part includes a second varistor element layer to exhibit nonlinear voltage-current characteristics, and a plurality of second internal electrodes juxtaposed in the second varistor element layer. The heat dissipation layer is located between the first and second varistor parts and is in contact with the first and second varistor parts.