Power Semiconductor Apparatus Insulating Section Thickness Control

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Solution Overview

Problem

Existing power semiconductor apparatuses face challenges in downsizing while maintaining high insulation reliability and heat dissipation due to issues with filler clogging and uneven thermal conductivity resin interfaces, leading to increased module size and reduced withstand voltage.

Innovation Solution

A power semiconductor apparatus with a lead frame, power die pad, and sealing resin that includes an insulating section with a uniform thickness of 1 to 4 times the maximum particle diameter, and a hollow above the power die pad, using compression molding to ensure uniform filling and high thermal conductivity, thereby preventing electric field concentration and enhancing insulation reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If transfer molding method is used to form insulating section, then sealing resin can be supplied into narrow gaps, but it is difficult to form insulating section with uniform thickness and filler gets clogged

Engineering Contradiction:

Improveuniform thickness of insulating sectionVSAvoidfiller clogging in narrow gaps

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent changes the thickness parameter of the insulating section to be 1 to 4 times the maximum particle diameter of filler particles. This parameter optimization prevents filler clogging while ensuring uniform thickness, resolving the contradiction between manufacturing precision and ease of manufacture.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a resin layer as an intermediary between the filler particles and the narrow gaps. This resin layer acts as a mediator that allows filler particles to be properly positioned without getting clogged, enabling both uniform thickness and ease of manufacture.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If insulating section thickness is increased to prevent filler clogging, then filler can flow through narrow gaps, but module size increases and heat dissipation performance decreases

Engineering Contradiction:

Improvefiller flow through narrow gapsVSAvoidmodule size

Core Design Contradiction:

Ease of manufactureVSVolume of stationary object

Solution Approach 1:

The patent optimizes the insulating section thickness parameter to the specific range of 1 to 4 times the maximum filler particle diameter. This precise parameter control allows filler to flow through narrow gaps without excessive thickness increase, preventing module size expansion while maintaining manufacturability.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If high thermal conductivity resin is molded separately on under surface, then thermal conductivity is improved, but interface bonding deteriorates and insulation reliability decreases

Engineering Contradiction:

Improvethermal conductivityVSAvoidinsulation reliability and bonding performance

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent merges the high thermal conductivity resin molding with the main sealing resin molding into a single integrated process. This combination ensures uniform thickness distribution and proper bonding at interfaces, maintaining both thermal conductivity and insulation reliability without the defects of separate molding.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent ensures homogeneous distribution of high thermal conductivity resin throughout the insulating section by controlling the molding process. This homogeneity prevents void formation and ensures uniform bonding, maintaining both thermal performance and insulation reliability.

Inventive Principle:

Principle #33Homogeneity

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 solution enables a smaller power semiconductor device with higher heat generation density, reducing module size and improving insulation reliability by preventing filler clogging and ensuring uniform thermal conductivity, thus maintaining high withstand voltage.

Implementation Method 1

using compression molding to ensure uniform filling

Methodology Applied

Scientific EffectCompression molding: Compression

Implementation Method 2

ensuring uniform thermal conductivity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

preventing electric field concentration and enhancing insulation reliability

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Data Source

PatentUS11107746B2Power semiconductor apparatus and manufacturing method therefor

Publication Date: 2021.08.31 MITSUBISHI ELECTRIC CORP

AI summary

A lead frame (4) includes an inner lead (5), an outer lead (2) connected to the inner lead (5), and a power die pad (7). A power semiconductor device (9) is bonded onto the power die pad (7). A first metal thin line (11) electrically connects the inner lead (5) and the power semiconductor device (9). Sealing resin (1) seals the inner lead (5), the power die pad (7), the power semiconductor device (9), and the first metal thin line (11). The sealing resin (1) includes an insulating section (15) directly beneath the power die pad (7). A thickness of the insulating section (15) is 1 to 4 times a maximum particle diameter of inorganic particles in the sealing resin (1). A first hollow (14) is provided on an upper surface of the sealing resin (1) directly above the power die pad (7) in a region without the first metal thin line (11) and the power semiconductor device (9).