Semiconductor Device Sealing Structure with Primer Layer
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Solution Overview
Problem
Conventional power semiconductor modules experience peeling and cracking due to thermal stress and moisture absorption, leading to reduced service life and power-cycling capability.
Innovation Solution
A semiconductor device with a sealing structure comprising a primer layer and two layers of resins with specific physical properties, where the first sealing layer has a lower inorganic filler content than the second sealing layer, optimizing the coefficient of linear thermal expansion and Young's modulus to reduce interface stress and maintain strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the content of inorganic filler in the sealing material is reduced to bring physical property values closer to the primer layer, then the interface stress is reduced and adhesion is improved, but the strength of the sealing material decreases leading to cracking
Solution Approach 1:
The sealing material is divided into a first sealing layer and a second sealing layer with different inorganic filler contents. The first sealing layer (contacting the primer layer) has lower inorganic filler content (60-75 wt%) to reduce interface stress and improve adhesion, while the second sealing layer (outer layer) has higher inorganic filler content (75-90 wt%) to provide high strength and prevent cracking. This segmentation allows each layer to optimize its properties for its specific function.
Solution Approach 2:
Different regions of the sealing material are assigned different inorganic filler contents based on their functional requirements. The inner region (first sealing layer) has lower filler content for flexibility and adhesion, while the outer region (second sealing layer) has higher filler content for strength and crack resistance. This local quality differentiation resolves the contradiction between adhesion and strength.
2Device complexity
If a single-layer sealing material is used, then the structure is simple, but it cannot simultaneously achieve both high strength and reduced interface stress
Solution Approach 1:
The sealing material is segmented into two distinct layers with different compositions optimized for different functions. The first sealing layer focuses on stress reduction and adhesion, while the second sealing layer focuses on strength and crack resistance. This segmentation enables the system to achieve high reliability under thermal cycling conditions without excessive complexity.
Solution Approach 2:
The sealing structure uses a composite of two resin materials with different inorganic filler contents. This composite approach allows the system to combine the benefits of both low-filler (flexible, adhesive) and high-filler (strong, rigid) materials, achieving superior power-cycling capability that neither single material could provide alone.
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 effectively suppresses peeling between the primer layer and the sealing material, enhancing the power-cycling capability and preventing cracking, thereby extending the service life of the semiconductor device.
Implementation Method 1
Further absorption of moisture with time degrades the covering resin layer, lowering the adhesion between the sealing material and the sealed members
Implementation Method 2
The coefficients of linear expansion of the resins themselves are larger than the coefficients of linear expansion of metal members such as the lead frame. Hence, when the semiconductor module undergoes heat cycles or the like, a high thermal stress is generated in the semiconductor module.
Data Source
AI summary
A semiconductor device in which a semiconductor element mounted on a laminate substrate and an electrically conductive connection member are sealed with a sealing material, includes: a primer layer in an interface between the sealing material and sealed members including the laminate substrate, the semiconductor element, and the electrically conductive connection member, in which the sealing material includes a first sealing layer which is provided in contact with the primer layer; and a second sealing layer which covers the first sealing layer, the semiconductor device satisfies αp≥α1>α2 in which αp, α1, and α2 represent coefficients of linear thermal expansion of the primer layer, the first sealing layer, and the second sealing layer, respectively, αc≥15×10−6/° C. in which αc represents a composite coefficient of linear thermal expansion of the sealing layers, and Ec≥5 GPa or more in which Ec represents a composite Young's modulus of the sealing layers.