Semiconductor Module Lead Frame Structure for Power Cycling Strain Relief

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Solution Overview

Problem

Conventional semiconductor modules experience strain and degradation of the front electrode due to thermal expansion and contraction during power cycling, leading to reduced reliability and power cycling capability.

Innovation Solution

Incorporating an insulating layer with a lower elastic modulus than the encapsulating material to reduce the support of the lead frame rising portion, allowing it to move freely and alleviate stress concentration on the front electrode, thereby enhancing the power cycling capability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the encapsulating material provides strong support to the lead frame rising portion, then the structural stability is improved, but the stress concentration on the front electrode increases during thermal cycling

Engineering Contradiction:

Improvestructural stabilityVSAvoidpower cycling capability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent applies local quality by creating a differentiated support structure: the insulating layer provides localized support at the bottom surface of the lead frame rising portion, while allowing freedom of movement at the front electrode bonding region. This spatial variation in support characteristics resolves the contradiction between overall structural stability and local stress reduction.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The insulating layer acts as an intermediary element between the encapsulating material and the lead frame rising portion. It mediates the stress transmission by providing distributed support that prevents excessive deformation while allowing controlled movement, thereby reducing stress concentration on the front electrode during thermal cycling.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If the lead frame rising portion is constrained to prevent deformation, then the structural integrity is improved, but the strain on the front electrode increases during thermal expansion

Engineering Contradiction:

Improvestructural integrityVSAvoidstrain on front electrode

Core Design Contradiction:

StrengthVSStress or pressure

Solution Approach 1:

The insulating layer serves as a pre-positioned cushioning element that absorbs and distributes thermal stresses before they can concentrate on the front electrode. By providing compliant support in advance, it prevents excessive deformation of the lead frame rising portion while accommodating thermal expansion, thereby protecting the front electrode from high strain.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If the encapsulating material directly supports the lead frame, then the manufacturing simplicity is maintained, but the power cycling reliability is reduced

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidpower cycling capability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent employs composite material structure by combining the encapsulating material with an insulating layer having different mechanical properties. This composite approach provides both the protective encapsulation function and the stress-distributing support function, improving power cycling reliability while maintaining manufacturing feasibility through integrated material selection.

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

The insulating layer reduces strain on the front electrode, improving the reliability and power cycling capability of the semiconductor module by preventing deformation and degradation of the lead frame rising portion.

Implementation Method 1

the insulating layer containing an electrical insulating material having an elastic modulus smaller than an elastic modulus of the encapsulating material

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

Conventional semiconductor modules experience strain and degradation of the front electrode due to thermal expansion and contraction during power cycling

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS20250210476A1Semiconductor module

Publication Date: 2025.06.26 FUJI ELECTRIC CO LTD

AI summary

A semiconductor module, including: a stacked substrate having, at a top surface thereof, a conductive plate; a semiconductor chip having a front surface and a back surface opposite to each other, the back surface being bonded to the top surface of the stacked substrate, the semiconductor chip having a front electrode at the front surface; a lead frame electrically connecting the front electrode and the conductive plate to each other, the lead frame having a first surface and a second surface opposite to each other, the second surface facing the stacked substrate; an encapsulating material encapsulating the semiconductor chip, the stacked substrate, and the lead frame; and an insulating layer provided on the lead frame, and facing the first surface of the lead frame in a thickness direction. The insulating layer contains an electrical insulating material having an elastic modulus smaller than that of the encapsulating material.