Power Module Spacer Design for Solder Thickness Control

Solution Overview

Problem

Conventional power modules face reliability issues due to thermal stress and fatigue in the bonding material between semiconductor power chips and substrates, leading to increased material costs and thermal resistance, as well as potential failure from uneven solder thickness and tilting of power chips.

Innovation Solution

The use of spacers, manufactured through metal powder sintering, thixotropic material, or wire bonding technologies, to support power chips on circuit-patterned substrates, controlling the thickness of the bonding material and reducing thermal stresses, thereby enhancing the reliability and uniformity of the bonding layer without increasing material usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the thickness of the solder is increased to ensure reliability, then the lifetime of the solder is improved, but the material cost increases and thermal resistance increases

Engineering Contradiction:

Improvelifetime of solderVSAvoidmaterial cost

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The bonding structure is segmented into three parts: substrate, solder layer, and power chip. The spacer is introduced as a separate component that divides the bonding function between the spacer (mechanical support) and solder (electrical and thermal connection), allowing optimized thickness of each component

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The spacer acts as an intermediary component between the substrate and power chip. It provides mechanical support and defines the solder thickness, eliminating the need to increase solder thickness for structural support while maintaining reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the thickness of the solder is increased to ensure reliability, then the lifetime of the solder is improved, but the thermal performance deteriorates

Engineering Contradiction:

Improvelifetime of solderVSAvoidthermal resistance

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The bonding structure is segmented into three parts: substrate, solder layer, and power chip. The spacer is introduced as a separate component that divides the bonding function between the spacer (mechanical support) and solder (electrical and thermal connection), allowing optimized thickness of each component

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The spacer acts as an intermediary component between the substrate and power chip. It provides mechanical support and defines the solder thickness, eliminating the need to increase solder thickness for structural support while maintaining reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If novel bonding materials and technologies are used to improve reliability, then the lifetime of the sandwich structure is improved, but the cost of materials and packaging processes increases

Engineering Contradiction:

Improvelifetime of sandwich structureVSAvoidcost of materials and packaging processes

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The spacer is designed to be self-supporting and automatically defines the solder thickness during the bonding process. It serves multiple functions (mechanical support, thickness control, alignment) without requiring complex equipment or specialized materials, making the process self-sufficient and cost-effective

Inventive Principle:

Principle #25Self-service

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 the reliability and thermal performance of power modules by controlling thermal stresses and maintaining uniform bonding material thickness, reducing material costs and thermal resistance, while preventing fatigue failure.

Implementation Method 1

The first spacer is employed to support the first power chip on the first circuit-patterned layer

Methodology Applied

Scientific EffectPhysical support and positioning:

Implementation Method 2

The first bonding material is employed to bond the first power chip onto the first circuit-patterned layer

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS10276522B2Power module

Publication Date: 2019.04.30 DELTA ELECTRONICS INC(CN)

AI summary

The disclosure discloses a power module. The power module includes a substrate, a power chip, a bonding material, and at least one spacer. The substrate includes a circuit-patterned layer. The power chip bonded to the circuit-patterned layer by the bonding material. The spacer is located between the circuit-patterned layer and the power chip, so as to keep the power chip away from the circuit-patterned layer in a distance.