Resin-Molded Power Semiconductor Package for Creepage Insulation
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Solution Overview
Problem
Conventional semiconductor devices with resin-molded type suffer from poor insulation performance due to the concentration of electric fields at the interface between different types of resins used for mounting and heat dissipation surfaces, leading to peeling and deterioration of insulation properties.
Innovation Solution
The semiconductor device incorporates a lead frame with a first insulation resin on the mounting surface and a second insulation resin with a higher thermal conductivity on the heat dissipation surface, featuring a second skirt portion that protrudes towards the mounting surface, increasing the creeping distance between the lead frame and the heatsink, thereby enhancing insulation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If two types of resins (mounting surface resin and heat dissipation surface resin) are used to seal the lead frame, then thermal conductivity is improved, but electric field concentration at the interface causes peeling and insulation deterioration
Solution Approach 1:
The patent applies local quality by creating a resin structure with varying properties: the first resin portion has lower viscosity and fills gaps to provide stress relief, while the second resin portion has higher viscosity and provides structural support. This localized differentiation resolves the contradiction by allowing each region to optimize for its specific function while maintaining overall insulation integrity.
Solution Approach 2:
The patent uses composite materials by combining two different resin types with distinct properties (different viscosities and thermal conductivities) into a unified sealing structure. The composite resin system maintains the thermal conductivity benefits while the interface design prevents peeling, thus resolving the insulation deterioration issue.
2Temperature
If a gap is provided between the lead frame and heatsink for heat dissipation, then thermal management is improved, but insulation distance is reduced leading to electrical breakdown risk
Solution Approach 1:
The patent introduces the resin material as an intermediary substance that fills the gap between the lead frame and heatsink. This intermediary provides both thermal conduction pathways for heat dissipation and electrical insulation to maintain adequate creepage distance, thus resolving the contradiction between thermal management and insulation requirements.
Solution Approach 2:
The patent changes the physical parameters of the gap by filling it with resin material that has specific thermal and electrical properties. This transforms the gap from a simple air space into a functional medium that simultaneously enables heat transfer and maintains electrical insulation, resolving the contradiction through parameter modification.
3Strength
If resin viscosity is increased to improve structural strength, then mechanical strength is improved, but gap filling ability and stress relief are reduced
Solution Approach 1:
The patent segments the resin system into two distinct portions with different viscosities: the first resin portion with lower viscosity (10-1000 Pa·s) for gap filling and stress relief, and the second resin portion with higher viscosity (100-10000 Pa·s) for structural strength. This segmentation allows each portion to optimize for its specific function without compromise.
Solution Approach 2:
The patent applies local quality by positioning different viscosity resins in specific locations: the lower viscosity resin is placed where gap filling and stress relief are critical, while the higher viscosity resin is positioned where structural support is needed. This spatial differentiation of material properties resolves the contradiction between strength and gap filling ability.
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 increased creeping distance between the lead frame and the heatsink improves insulation performance and prevents heat dissipation reduction, ensuring adequate strength and insulation distance at the outer peripheral end, thus enhancing the overall reliability of the semiconductor device.
Implementation Method 1
a first insulation resin portion (7) formed on a mounting surface side of the lead frame (2); a second insulation resin portion (8) formed on a heat dissipation surface side of the lead frame (2)
Implementation Method 2
a second insulation resin portion (8) formed on a heat dissipation surface side of the lead frame (2), wherein the second insulation resin portion (8) has a higher thermal conductivity than the first insulation resin portion (7)
Data Source
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AI summary
This semiconductor device includes: a first insulation resin portion (7) formed on the mounting surface side of a lead frame (2); a second insulation resin portion (8) formed on the heat dissipation surface side of the lead frame (2); and a heatsink (50) fixed to the heat dissipation surface of the second insulation resin portion (8), wherein the second insulation resin portion (8) has a second skirt portion (8a) formed at an end of a thin molded portion (8b), the first insulation resin portion (7) has a first skirt portion (7a) covering the second skirt portion (8a), and an outer peripheral surface part of the second skirt portion (8a) has a first end (T1) connected to the lead frame (2) and the first skirt portion (7a), a second end (T2) connected to the heatsink (50), and at least one bent portion (R1) formed between the first end (T1) and the second end (T2).