Circuit Module Resin Segmentation to Reduce Tensile Stress
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Solution Overview
Problem
The contraction of sealing resin in circuit modules can cause tensile stress, leading to cracks in the connection portions of electronic components exposed to empty portions, due to factors like soldering, heat generation, and environmental temperature changes.
Innovation Solution
A circuit module design where the sealing resin portion covers at least the side surfaces of the components but avoids the upper surface regions corresponding to empty portions, reducing the upward force exerted on the components and minimizing the risk of cracks. This is achieved by using a resin with a lower contraction factor for the first component and a different resin for the sealing resin portion, and optionally employing a second resin with a lower Young's modulus to absorb contraction stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing resin is used to cover the electronic component, then the component is sealed and protected, but tensile stress from resin contraction causes cracks in the connection portion
Solution Approach 1:
The patent divides the sealing resin into two distinct portions: a first sealing resin that covers the side surface and part of the upper surface of the electronic component, and a second sealing resin that covers the remaining upper surface. This segmentation allows each resin portion to have optimized properties - the first resin can be positioned to minimize stress on the connection portion while the second resin provides additional sealing coverage.
Solution Approach 2:
The patent applies different sealing resins with different characteristics to different regions of the electronic component. The first sealing resin is specifically positioned to avoid exerting excessive tensile stress on the connection portion, while the second sealing resin covers other areas. This local differentiation of material properties resolves the contradiction between providing comprehensive sealing and protecting the vulnerable connection portion.
2Reliability
If the sealing resin covers the entire upper surface, then complete sealing is achieved, but the connection portion exposed to empty portion is subjected to upward tensile stress
Solution Approach 1:
The sealing resin is segmented into a first sealing resin and a second sealing resin with distinct coverage areas. The first sealing resin is strategically positioned to cover the side surface and part of the upper surface while deliberately avoiding direct coverage of the connection portion region. This segmentation enables complete sealing of the electronic component while eliminating the harmful upward tensile stress that would otherwise be exerted on the connection portion.
Solution Approach 2:
The first sealing resin acts as an intermediary element that provides sealing protection to the side surface and upper surface while its specific positioning and material properties mediate to reduce stress transmission to the connection portion. The second sealing resin then provides additional sealing coverage without the same stress issues, together achieving complete sealing while protecting the connection portion.
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 design effectively prevents cracks in the connection portions by reducing tensile stress from resin contraction, ensuring the reliability and integrity of the circuit module, while maintaining a flat upper surface and preventing water ingress.
Implementation Method 1
In solidification of resin performed so as to seal an electronic component with the resin, contraction of the resin may cause upward tensile stress against the electronic component
Implementation Method 2
the electronic component body is electrically connected to a substrate or the like with the connection portion interposed therebetween
Data Source
AI summary
A circuit module (101) includes a substrate (1) having a principal surface (1a), a first component (6) mounted on the principal surface (1a), and a sealing resin portion (3) that covers at least a side surface of the first component (6) while covering the principal surface (1a). The first component (6) includes an empty portion (6c) and a connection portion (6b) exposed to the empty portion (6c). The sealing resin portion (3) is arranged to avoid at least a part of a region that is included in an upper surface of the first component (6) and corresponds to the empty portion (6c).