Ultrasonic Bonding of Semiconductor Electrode Terminals

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Solution Overview

Problem

Conventional ultrasonic bonding techniques for semiconductor devices face challenges such as thermal stress-induced peeling and reduced bonding strength due to increased stiffness and thickness of electrode terminals, as well as difficulties in energy propagation across larger bonding areas, which can lead to substrate damage.

Innovation Solution

The semiconductor device employs multiple bonding positions with recesses on the electrode terminal and a conductive pattern, allowing for reduced thermal stress and increased bonding area, facilitating stable ultrasonic bonding and enhanced reliability by engaging projections and depressions for precise positioning and energy distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the electrode terminal thickness or width is increased to carry larger current, then the current carrying capacity is improved, but the stiffness increases causing increased stress on the bonding portion and displacement of the package due to heat, leading to reduced bonding strength and terminal peeling

Engineering Contradiction:

Improvecurrent carrying capacityVSAvoidbonding strength

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The bonding face is divided into multiple bonding positions (at least two positions) instead of a single bonding area. This segmentation distributes the stress and thermal load across multiple discrete bonding locations, preventing concentrated stress that would lead to peeling while maintaining the overall bonding strength required for high current applications.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different bonding characteristics to different locations on the bonding face. By creating multiple distinct bonding positions with potentially varying areas and configurations, each location can be optimized for its specific stress and thermal conditions, improving overall reliability under high current and temperature conditions.

Inventive Principle:

Principle #3Local quality

2Reliability

If the bonding load and ultrasonic output are increased to increase bonding strength, then the bonding reliability is improved, but the insulating substrate under the conductive pattern is damaged

Engineering Contradiction:

Improvebonding strengthVSAvoidsubstrate damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

By dividing the bonding process into multiple discrete bonding positions rather than applying ultrasonic energy to a large continuous area, the patent reduces the total ultrasonic energy required. Each small bonding position receives controlled, localized energy that is sufficient for strong bonding without exceeding the damage threshold for the insulating substrate.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of applying excessive ultrasonic energy to the entire bonding face, the patent applies partial action by limiting ultrasonic bonding to specific discrete positions. This partial application of bonding energy achieves sufficient bonding strength while avoiding the excessive energy input that would damage the substrate.

Inventive Principle:

Principle #16Partial or excessive action

3Device complexity

If ultrasonic bonding is performed at one position, then the process is simple, but thermal stress generated under high temperature conditions causes the bonding portion to peel off

Engineering Contradiction:

Improvebonding process complexityVSAvoidbonding durability under thermal stress

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent divides the single bonding position into multiple bonding positions (at least two). This segmentation creates multiple stress distribution points that prevent concentrated thermal stress at any single location, thereby preventing peeling under high temperature conditions while maintaining relatively simple processing.

Inventive Principle:

Principle #1Segmentation

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 configuration reduces thermal stress on bonding areas, enhances bonding reliability, and prevents peeling, resulting in a highly reliable semiconductor device capable of withstanding high temperatures and currents.

Implementation Method 1

the electrode terminal and the conductive pattern are bonded together by the ultrasonic bonding

Methodology Applied

Scientific EffectUltrasonic bonding: Ultrasonic Vibration

Data Source

PatentUS10522482B2Semiconductor device manufacturing method comprising bonding an electrode terminal to a conductive pattern on an insulating substrate using ultrasonic bonding

Publication Date: 2019.12.31 MITSUBISHI ELECTRIC CORP

AI summary

An object of the present invention is to obtain a semiconductor device having highly reliable bonding portions. The semiconductor device according to the present invention includes an insulating substrate on which a conductive pattern is formed, and an electrode terminal and a semiconductor element which are bonded to the conductive pattern, the electrode terminal and the conductive pattern are bonded by ultrasonic bonding on a bonding face, and the ultrasonic bonding is performed at a plurality of positions.