Indium Bonded Radiating Plate for Semiconductor Thermal Management

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Solution Overview

Problem

Existing methods for attaching a radiating plate to a semiconductor device using thermal conductors like solder or high-temperature resin can cause thermal stress and voids, leading to reduced thermal conductivity and potential damage to the semiconductor device.

Innovation Solution

A method using Indium (In) as a thermal conducting bonding material, which is melted and hermetically adhered to the radiating plate, eliminating the need for high-temperature heating and ensuring a void-free bond, thereby enhancing thermal conductivity and reducing assembly stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-temperature heating is used to melt solder or high-temperature conducting resin for bonding, then thermal conductivity between semiconductor device and radiating plate is improved, but thermal stress is generated causing damage to semiconductor device

Engineering Contradiction:

Improvethermal conductivityVSAvoidthermal stress

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the bonding temperature parameter from high-temperature (soldering) to low-temperature (room temperature or slightly elevated) by using indium foil as the bonding material. This parameter change allows achieving good thermal conductivity without generating excessive thermal stress that damages the semiconductor device.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses indium foil as a consumable bonding material that is pressed and bonded at low temperature. The indium foil serves both as bonding material and thermal conductor, eliminating the need for high-temperature soldering processes while maintaining effective thermal coupling.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Strength

If solder is used as thermal conductor and melted for bonding, then bonding strength is improved, but voids are generated reducing thermal conductivity

Engineering Contradiction:

Improvebonding strengthVSAvoidthermal conductivity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention replaces the thermal-melting process (soldering) with a mechanical pressing process. Indium foil is bonded by applying pressure at room temperature or slightly elevated temperatures, avoiding the melting and solidification process that creates voids. The mechanical pressing ensures complete contact and eliminates void formation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the bonding mechanism from thermal-melting to mechanical-pressing. By controlling pressure and temperature parameters (low temperature, high pressure), the indium foil bonds effectively without generating voids, maintaining both bonding strength and thermal conductivity.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If high-temperature conducting resin is used to prioritize good filling condition, then clearance filling is improved, but thermal conductivity is reduced compared to metal materials

Engineering Contradiction:

Improveclearance fillingVSAvoidthermal conductivity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The invention uses indium, a metal material with excellent thermal conductivity properties, as the bonding and thermal conduction medium. The indium foil provides both good clearance filling capability and high thermal conductivity, overcoming the limitation of polymer-based conducting resins that prioritize filling but sacrifice thermal performance.

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

This approach improves thermal conductivity, reduces void formation, and minimizes thermal stress on the semiconductor device, resulting in a more efficient heat radiating semiconductor apparatus with reduced assembly time and damage risk.

Implementation Method 1

heating and melting the In and hermetically adhering the In to the radiating plate

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

heating and melting the In and hermetically adhering the In to the radiating plate

Methodology Applied

Scientific EffectThermal bonding:

Implementation Method 3

enhance the thermal radiating property thereof

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS7445965B2Method of manufacturing radiating plate and semiconductor apparatus using the same

Publication Date: 2008.11.04 SHINKO ELECTRIC IND CO LTD

AI summary

A method of manufacturing a radiating plate using In as a thermal conducting bonding material 20 provided between a semiconductor device and a radiating plate 14 and serving to bond a back surface of the semiconductor device to the radiating plate, includes the steps of carrying out a cleaning treatment for cleaning a surface of the radiating plate 14, supplying the In to the radiating plate 14, heating and melting the In and hermetically adhering the In 18 to the radiating plate, thereby obtaining an In integral type radiating plate.