Embedded Component Module Resin Thickness Ratio
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Solution Overview
Problem
The existing encapsulation methods for electronic modules face challenges with short-circuit failures during the reflow-mounting process due to solder remelt expansion pressure and thermal expansion of the resin, which can lead to delamination and undesirable linkages between components, requiring specialized resins that are costly and difficult to mold.
Innovation Solution
The module design incorporates a substrate with electronic components such as resistors, capacitors, and coils, where the components have two electrode portions connected by solder, and the encapsulating resin is strategically positioned to maintain a specific thickness and distance ratio (b/a not more than 6) to prevent solder flow and thermal stress, using conventional resins without altering the reflow process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a special resin with both mechanical strength and flexibility is used to prevent solder remelt expansion pressure, then short-circuit prevention is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention changes the geometric parameters of the module structure, specifically controlling the ratio of encapsulating resin thickness (b) to the distance from component mounting surface to component lower surface (a) to be not more than 6. This parameter control allows the use of conventional resins with standard properties while preventing solder remelt expansion issues, eliminating the need for special flexible resins and reducing manufacturing complexity
Solution Approach 2:
The invention addresses the solder expansion pressure problem not by changing resin material properties, but by controlling the three-dimensional geometric relationship between components and encapsulating resin. By managing the b/a ratio, the design redistributes thermal and mechanical stresses through spatial configuration rather than material selection
2Strength
If the encapsulating resin thickness is increased to protect internal components, then mechanical protection is improved, but solder remelt expansion pressure increases causing delamination
Solution Approach 1:
The invention optimizes the thickness parameter of the encapsulating resin by controlling the b/a ratio. This ensures the resin provides sufficient mechanical protection while maintaining adequate proximity to components to manage thermal expansion and solder remelt pressure, preventing delamination without excessive thickness
3Ease of manufacture
If conventional resins are used for encapsulation, then manufacturing cost is reduced, but solder remelt expansion causes short-circuit failures
Solution Approach 1:
The invention enables the use of conventional, cost-effective resins by controlling the geometric parameter b/a to be not more than 6. This parameter control creates sufficient thermal management and stress distribution that prevents solder remelt expansion issues, achieving both low cost and high reliability
Solution Approach 2:
The invention replaces expensive special flexible resins with conventional, readily available resin materials. By using standard materials with proven manufacturing processes, the invention reduces material costs and supply chain complexity while maintaining reliability through geometric design
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 effectively prevents short-circuit failures during reflow-mounting by managing thermal and melt expansion pressures, allowing for reliable module assembly using standard resins and conventional reflow conditions, reducing costs and improving manufacturing efficiency.
Implementation Method 1
When the solder remelts, it undergoes melt expansion and produces a pressure (remelt expansion pressure)
Implementation Method 2
the ability (mechanical strength) to protect internal components and flexibility capable of reducing the remelt expansion pressure of the solder
Data Source
AI summary
In a module with embedded electronic components, connection electrodes are formed on the component mounting surface of a substrate. The electrode portions of each of the electronic components are placed on the individual connection electrodes and connected in fixed relation thereto by using a solder. The electronic components are encapsulated in an encapsulating resin. When the distance between the lower surface of the main body portion of each of the electronic components and the component mounting surface is assumed to be a and the thickness of the portion of the encapsulating resin which is located above the main body portion of the electronic component is assumed to be b, if b/a is set to a value of not more than 6, it becomes possible to prevent, when the module with embedded electronic components is reflow-mounted on a printed wiring substrate or the like, the occurrence of a short circuit failure resulting from the melting and flowing of the solder which causes a short circuit between the two electrode portions.