Ceramic Evaporator for Semiconductor Thermal Matching

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Solution Overview

Problem

Conventional two-phase passive loop heat transfer systems face challenges in thermally matching materials with semiconductor heat sources, leading to high thermal resistance and unreliable packaging due to differences in thermal expansion coefficients, and they often require bulky indirect cooling methods.

Innovation Solution

The development of an evaporator with a ceramic vapor barrier wall and liquid barrier wall, both thermally and electrically insulating, with a ceramic wick, allowing for a low thermal resistance interface and direct bonding to semiconductor heat sources, and fabricated using stereolithography for complex geometries and high precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional materials are used in two-phase passive loop heat transfer systems, then the system structure is simple, but thermal resistance increases and reliability decreases due to mismatched thermal expansion coefficients with semiconductor heat sources

Engineering Contradiction:

Improvepackaging reliabilityVSAvoidevaporator structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The evaporator employs a composite structure consisting of a ceramic vapor barrier wall, a ceramic liquid barrier wall, and a ceramic wick material. This composite ceramic construction enables thermal expansion matching with semiconductor heat sources while maintaining the two-phase heat transfer function, thereby improving packaging reliability without excessive complexity

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention changes the material parameters of the evaporator components by using ceramic materials with specific thermal expansion coefficients that match semiconductor heat sources. This parameter adjustment resolves the thermal expansion mismatch problem and improves reliability

Inventive Principle:

Principle #35Parameter changes

2Productivity

If indirect cooling methods are used, then material thermal expansion mismatch is reduced, but the system becomes bulky and heat transfer efficiency decreases

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidpackaging reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention uses homogeneous ceramic materials for the vapor barrier wall, liquid barrier wall, and wick, all with matched thermal expansion coefficients. This homogeneity enables direct bonding to semiconductor heat sources without the thermal expansion mismatch problems that plague indirect cooling methods, achieving both high heat transfer efficiency and packaging reliability

Inventive Principle:

Principle #33Homogeneity

3Reliability

If ceramic materials are used for barrier walls and wick, then thermal expansion matching with semiconductor heat sources is achieved, but manufacturing complexity increases

Engineering Contradiction:

Improvethermal cycling reliabilityVSAvoidevaporator manufacturing ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the material parameters by selecting ceramic materials with thermal expansion coefficients that match semiconductor heat sources. This parameter change improves thermal cycling reliability while the materials selected maintain reasonable manufacturability through established ceramic fabrication techniques

Inventive Principle:

Principle #35Parameter changes

4Productivity

If direct bonding to semiconductor heat sources is implemented, then thermal resistance is reduced, but packaging space requirements increase

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidpackaging volume

Core Design Contradiction:

ProductivityVSVolume of moving object

Solution Approach 1:

The homogeneous ceramic construction of the evaporator enables direct bonding to semiconductor heat sources with minimal interface thickness, reducing thermal resistance while maintaining compact packaging. The matched thermal expansion coefficients prevent interface degradation, allowing for thin, efficient heat transfer paths

Inventive Principle:

Principle #33Homogeneity

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 design enables efficient heat transfer with low thermal resistance, improved reliability against thermal cycling, and compact packaging by matching thermal expansion coefficients and allowing direct integration with semiconductor devices, while also serving as an insulating substrate for electronic components.

Implementation Method 1

These systems utilize capillary pressure developed in a fine-pored wick within the evaporator to promote circulation of working fluid from the evaporator to the condenser and back to the evaporator

Methodology Applied

Scientific EffectCapillary pressure: Capillary Pressure

Implementation Method 2

Heat acquired by the evaporator is transported to and discharged by the condenser

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 3

an evaporator thermally coupled to the heat source

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS7848624B1Evaporator for use in a heat transfer system

Publication Date: 2010.12.07 NORTHROP GRUMMAN SYSTEMS CORP

AI summary

An evaporator includes a liquid barrier wall made of a ceramic material, a vapor barrier wall made of a ceramic material, and a wick made of a ceramic material and being positioned between the liquid barrier wall and the vapor barrier wall.