Semiconductor Electrode Layout for Thermal Stress Relief

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Solution Overview

Problem

Conventional semiconductor devices face reliability issues due to thermal stress caused by differences in thermal expansion coefficients between the strap member and the semiconductor element, leading to potential damage and reduced device reliability.

Innovation Solution

The semiconductor device incorporates a first conductive member with a first pad part that includes a bonding surface, a main surface, and a non-bonding portion. The non-bonding portion overlaps with the finger electrode portion of the second electrode and is not bonded to the first electrode, reducing the constrained region and alleviating thermal stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the strap member covers almost the entire surface of the electrode to ensure electrical connection, then the electrical connectivity is improved, but thermal stress increases due to difference in thermal expansion coefficients between the strap member and semiconductor element

Engineering Contradiction:

Improveelectrical connectivityVSAvoidthermal stress

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The conductive member is divided into a bonding portion (covering the pad electrode portion) and a non-bonding portion (overlapping the finger electrode portion but not bonded). This segmentation allows the bonding portion to ensure electrical connectivity while the non-bonding portion reduces thermal stress by not constraining the finger electrode during thermal expansion.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the conductive member have different functional qualities: the bonding portion provides strong electrical connection and mechanical bonding, while the non-bonding portion provides thermal stress relief. This local differentiation of function resolves the contradiction between connectivity and stress reduction.

Inventive Principle:

Principle #3Local quality

2Strength

If the conductive member is rigid to maintain structural stability, then mechanical strength is improved, but thermal stress concentration increases leading to potential damage

Engineering Contradiction:

Improvemechanical strengthVSAvoiddamage resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The conductive member is segmented into bonding and non-bonding portions, allowing the bonding portion to provide mechanical strength while the non-bonding portion acts as a stress-relief zone that prevents crack propagation and thermal damage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The non-bonding portion is designed in advance to serve as a cushioning zone that absorbs and distributes thermal stress before it can concentrate and cause damage to the semiconductor element or the conductive member itself.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the bonding surface covers the entire electrode surface to reduce internal resistance, then electrical conductivity is improved, but thermal expansion mismatch causes stress concentration

Engineering Contradiction:

Improveinternal resistanceVSAvoidstress concentration

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The bonding surface is segmented to cover only the pad electrode portion where low internal resistance is needed, while the finger electrode portion has a non-bonding overlay that prevents stress concentration. This selective bonding approach resolves the contradiction between conductivity and stress management.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The conductive member exhibits local quality differentiation: high bonding coverage over the pad electrode for low resistance, and reduced bonding coverage over the finger electrode for stress relief. This localized functional differentiation simultaneously achieves both goals.

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 configuration enhances the reliability of the semiconductor device by preventing damage from thermal stress and improving heat dissipation, while also reducing internal resistance and allowing for flexible design of the first lead to accommodate different finger electrode arrangements.

Implementation Method 1

the thermal expansion coefficients of the strap member and the semiconductor element are not necessarily equal. Therefore, thermal stress caused by a difference in the thermal expansion coefficients is generated

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

a bonding surface bonded to the first electrode

Methodology Applied

Scientific EffectBonding: Adhesive

Implementation Method 3

a finger electrode portion for reducing an internal resistance of the second electrode

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS12347752B2Semiconductor device

Publication Date: 2025.07.01 ROHM CO LTD

AI summary

There is provided a semiconductor device, including: a semiconductor element which includes an element main surface and an element rear surface that face opposite sides in a thickness direction and in which a first electrode and a second electrode are formed on the element main surface; a first conductive member electrically connected to the first electrode; a second conductive member electrically connected to the second electrode; and a sealing resin configured to cover part of the first conductive member, part of the second conductive member, and the semiconductor element.