Semiconductor Device Terminal Design for Thermal Management

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Solution Overview

Problem

Conventional semiconductor devices face challenges in reducing package size and cost while maintaining high current density and withstand voltage, due to limitations in tracking resistance of resin and insulation materials, and the complexity of assembly with springs for heat dissipation.

Innovation Solution

A semiconductor device design featuring a metal block with a semiconductor element and terminals fixed using joining materials, covered by mold resin, where the metal block is exposed from the back and terminals are exposed from the sides, allowing direct connection to circuit patterns and eliminating the need for a pressing mechanism, thereby reducing size and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a holding spring is used to press the package against the cooler to prevent resin creep, then heat dissipation reliability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improveheat dissipation reliabilityVSAvoidassembly complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the holding spring from the package structure by redesigning the terminal configuration. The main terminal is extended to directly contact the cooler surface, providing mechanical pressure without requiring a separate spring component, thus simplifying the device structure while maintaining heat dissipation reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The main terminal serves dual functions: electrical connection and mechanical pressing force application. By extending the main terminal to contact the cooler, it simultaneously provides the pressing force needed to prevent resin creep and maintain thermal contact, eliminating the need for a dedicated holding spring

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If ceramic insulating material is used for insulation with the cooler, then insulation performance and current carrying capacity are improved, but manufacturing cost increases

Engineering Contradiction:

Improveinsulation performanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention replaces expensive ceramic insulating material with a cost-effective resin-based insulation structure. The mold resin is extended to cover the cooler contact area, providing sufficient insulation performance at lower cost, accepting that resin has limitations but leveraging the specific application requirements to achieve adequate performance

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If the package size is reduced to lower cost, then manufacturing cost decreases, but tracking resistance of resin and insulation performance deteriorate

Engineering Contradiction:

Improvemanufacturing costVSAvoidtracking resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention applies different material properties to different regions of the package. The mold resin is extended specifically in the area contacting the cooler to provide localized insulation enhancement, while maintaining overall compact dimensions. This targeted approach preserves tracking resistance where needed without requiring universal material upgrades that would increase cost

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 design enables a reduction in size and cost while ensuring high thermal conductivity and insulation, simplifying assembly, and reducing inductance by eliminating the need for springs and unnecessary wiring.

Implementation Method 1

a first joining material in which a semiconductor element is fixed to an upper surface of the metal block

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a second joining material with which a main terminal is fixed to an upper surface of the semiconductor element

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

a mold resin that covers the semiconductor element, the first joining material, and the second joining material, and covers a part of the metal block

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Data Source

PatentUS20230012134A1Semiconductor device

Publication Date: 2023.01.12 MITSUBISHI ELECTRIC CORP

AI summary

A semiconductor device includes: a metal block; a semiconductor element fixed to an upper surface of the block with a first joining material; a main terminal fixed to an upper surface of the element with a second joining material; a signal terminal electrically connected to the element; and a mold resin covers the element, the first and second joining materials, a part of the block, of the main and signal terminals. In the element, a current flows in a longitudinal direction. A lower surface of the block is exposed from the resin. The main and the signal terminals are exposed from a side surface of the resin. The main terminal has a first portion in the resin, a second portion continuous with the first portion and bent downward outside the resin, and a third portion continuous with the second portion and substantially parallel to a lower surface of the resin.