Constricted Sintered Bumps for Thermal-Stress-Resistant Bipolar Packaging

Solution Overview

Problem

Existing semiconductor modules face challenges in maintaining reliability due to bump distortion caused by thermal stress, which is exacerbated by complex configurations and processes for controlling bump bonding height.

Innovation Solution

A semiconductor module design featuring a laminated substrate with a circuit pattern and heat dissipating plate, using bumps made of sintered metal with a constricted middle portion to reduce thermal stress, and a manufacturing method involving a bump application and bonding step to form a tapered cone shape.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the bonding height of the bump is increased to reduce stress concentration, then the reliability of the apparatus is improved, but the configuration and process become complicated, causing cost increase

Engineering Contradiction:

Improveapparatus reliabilityVSAvoidbump configuration complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention changes the geometric parameters of the bump by forming a constricted shape at the center portion through a specific forming process. This parameter change (creating the constricted geometry) directly reduces stress concentration and improves reliability without requiring complex multi-step height adjustment processes or additional components.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention applies local quality by creating a constricted shape specifically at the center portion of the bump, while the bonding portions at the top and bottom maintain their full diameter. This localized geometric modification targets the stress concentration area without affecting the bonding interfaces, thereby improving reliability with a simple process.

Inventive Principle:

Principle #3Local quality

2Reliability

If the bonding height of the bump is increased to reduce stress concentration, then the reliability of the apparatus is improved, but the manufacturing process becomes complicated, causing cost increase

Engineering Contradiction:

Improveapparatus reliabilityVSAvoidbump manufacturing simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the geometric parameters of the bump by forming a constricted shape at the center portion through a specific forming process. This parameter change (creating the constricted geometry) directly reduces stress concentration and improves reliability without requiring complex multi-step height adjustment processes or additional components.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention applies local quality by creating a constricted shape specifically at the center portion of the bump, while the bonding portions at the top and bottom maintain their full diameter. This localized geometric modification targets the stress concentration area without affecting the bonding interfaces, thereby improving reliability with a simple process.

Inventive Principle:

Principle #3Local quality

3Reliability

If a constricted shape is formed at the center of the bump to reduce stress concentration, then the reliability is improved, but the manufacturing process becomes complex

Engineering Contradiction:

Improvebonding reliabilityVSAvoidbump formation process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention changes the geometric parameters of the bump by forming a constricted shape at the center portion through a specific forming process. This parameter change (creating the constricted geometry) directly reduces stress concentration and improves reliability without requiring complex multi-step height adjustment processes or additional components.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention applies local quality by creating a constricted shape specifically at the center portion of the bump, while the bonding portions at the top and bottom maintain their full diameter. This localized geometric modification targets the stress concentration area without affecting the bonding interfaces, thereby improving reliability with a simple process.

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

The design effectively reduces bump distortion and enhances reliability by dispersing thermal stress, achieving a simpler and more cost-effective configuration.

Implementation Method 1

The bump is made of a metal sintered material such that the bump is formed into a shape of being constricted in its middle portion

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS12451454B2Manufacturing method of packaging structure for bipolar transistor with constricted bumps

Publication Date: 2025.10.21 FUJI ELECTRIC CO LTD

AI summary

A semiconductor module includes a laminated substrate having an insulating plate, a circuit pattern arranged on an upper surface of the insulating plate and a heat dissipating plate arranged on a lower surface of the insulating plate. The semiconductor module also includes a semiconductor device having a collector electrode arranged on its upper surface, having an emitter electrode and a gate electrode arranged on its lower surface, and bumps respectively bonding the emitter electrode and the gate electrode to an upper surface of the circuit pattern. Each of the bumps is made of a sintered metal such that the bump is formed to be constricted in its middle portion in a thickness direction orthogonal to a surface of the insulating plate.