Liquid Metal Thermal Interface Material Faraday Cage for IC Packages

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Solution Overview

Problem

The use of liquid metal thermal interface materials (LM-TIMs) in IC packages increases the risk of electrical interference, such as crosstalk coupling, signal impedance, and electromagnetic interference, due to their metallic nature and liquid properties, which complicates containment and leads to corrosion and shorting risks, limiting their widespread adoption.

Innovation Solution

Incorporating a liquid metal thermal interface material as an integral part of a die-level Faraday cage within the IC package, where it is electrically coupled to a ground plane layer through solder resist openings or conductive barriers, providing both thermal cooling and electromagnetic shielding, thus mitigating electrical interference and ensuring compliance with electromagnetic compatibility regulations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If liquid metal thermal interface material is used to improve thermal cooling performance, then heat dissipation efficiency is improved, but electrical interference risk increases

Engineering Contradiction:

Improveheat dissipation efficiencyVSAvoidelectrical interference risk

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

A barrier layer is introduced as an intermediary between the liquid metal TIM and the substrate. This barrier layer is thermally conductive to maintain heat dissipation efficiency while being electrically resistive to block electrical interference and prevent corrosion, thus resolving the contradiction between thermal performance and electrical safety

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The solution uses a composite structure combining the liquid metal TIM with a barrier layer made of electrically resistive material. This composite approach allows the system to simultaneously achieve high thermal conductivity from the liquid metal and electrical isolation from the barrier layer, addressing both thermal performance and electrical interference concerns

Inventive Principle:

Principle #40Composite materials

2Temperature

If liquid metal TIM is used to enhance thermal conductivity, then thermal performance is improved, but corrosion and shorting risks increase

Engineering Contradiction:

Improvethermal conductivityVSAvoidcorrosion and shorting risks

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The barrier layer serves as a protective intermediary that prevents direct contact between the liquid metal TIM and the substrate, thereby eliminating corrosion risks while maintaining the thermal conductivity benefits of the liquid metal

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The barrier layer is applied beforehand to protect the substrate from potential corrosion and shorting effects of the liquid metal TIM before the TIM is applied, preventing reliability issues before they can occur

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Temperature

If liquid metal TIM is used to improve heat dissipation, then thermal cooling is improved, but electromagnetic interference increases

Engineering Contradiction:

Improvethermal coolingVSAvoidelectromagnetic interference

Core Design Contradiction:

TemperatureVSObject-generated harmful factors

Solution Approach 1:

The barrier layer acts as an intermediary that blocks electromagnetic interference generated by the liquid metal TIM while allowing thermal energy to pass through, thus maintaining thermal cooling performance while reducing electromagnetic interference

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The barrier layer provides localized electrical resistance at the interface between the liquid metal TIM and the substrate, creating a zone of electrical isolation precisely where needed to prevent electromagnetic interference while preserving thermal conductivity in the same location

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

This solution effectively reduces electrical interference, enhances System on a Chip immunity to external RF noises and electrostatic discharges, and eliminates radiated emissions, allowing for the widespread adoption of LM-TIMs while maintaining thermal performance.

Implementation Method 1

a thermal interface material (TIM) is sometimes used to thermally couple components of the package. Additionally, a TIM can be used to dissipate heat between components of the package

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

Incorporating a liquid metal thermal interface material as an integral part of a die-level Faraday cage within the IC package

Methodology Applied

Scientific EffectFaraday cage effect: Faraday Cage

Data Source

PatentUS11616000B2Methods and apparatus to provide electrical shielding for integrated circuit packages using a thermal interface material

Publication Date: 2023.03.28 INTEL CORP

AI summary

Methods and apparatus are disclosed to provide electrical shielding for integrated circuit packages using a thermal interface material. An integrated circuit package includes a substrate including a ground plane layer and a solder mask; a semiconductor die attached to the substrate, the solder mask layer separating the semiconductor die from the ground plane layer; and a thermal interface material surrounding at least a portion of the semiconductor die, the thermal interface material electrically coupled to the ground plane layer.