Encapsulating Resin Thermal Expansion Control for Module Delamination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The reduction in size and weight of electronic equipment has led to issues such as short-circuits and moisture absorption in electronic component integrated modules, particularly due to re-melted solder causing lift phenomena and interfacial delamination, especially when using organic wiring boards.
Innovation Solution
An electronic component integrated module is fabricated using a wiring board with an encapsulating resin having an average linear thermal expansion coefficient between 17×10−6/°C and 110×10−6/°C, which is achieved by calculating α={α1×(Tg−Tr)+α2×(Tp−Tg)/(Tp−Tr), where α1 and α2 are thermal expansion coefficients at temperatures below and above the glass transition temperature, respectively, and Tp is the peak temperature of packaging, to prevent lift and interfacial delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If organic wiring board is used to reduce cost and weight, then cost and weight are reduced, but moisture absorption increases and reflow resistance degrades
Solution Approach 1:
The patent changes the thermal expansion parameter of the encapsulating resin by selecting materials with specific thermal expansion coefficients (α1 and α2) to match the organic wiring board. This parameter matching prevents delamination caused by thermal stress during reflow processing, thereby improving reflow resistance while maintaining the benefits of using organic wiring boards for cost and weight reduction.
Solution Approach 2:
The patent uses a composite encapsulating resin system that combines multiple resin components with different thermal expansion characteristics. This composite approach allows the encapsulating resin to exhibit tailored thermal expansion properties that compensate for the high moisture absorption tendency of organic wiring boards, improving overall reliability without sacrificing the weight and cost advantages.
2Adaptability or versatility
If secondary packaging reflow is performed to provide module on mother board, then module integration is achieved, but solder re-melts causing short-circuit
Solution Approach 1:
The patent utilizes thermal expansion principles by designing the encapsulating resin with specific thermal expansion coefficients that match both the organic wiring board and the solder joints. During secondary packaging reflow, this thermal expansion matching prevents differential stress that would cause solder re-melting and short-circuits, while still allowing the module to be integrated onto the mother board.
Solution Approach 2:
The encapsulating resin serves as a protective cushioning layer that is applied beforehand to the module components. This resin layer absorbs and distributes thermal stress during subsequent reflow processing, preventing solder joints from re-melting and causing short-circuits, while maintaining the module's ability to be integrated onto the mother board.
3Ease of operation
If voltage is applied between terminals of chip component, then electrical function is activated, but solder migrates causing short-circuit
Solution Approach 1:
The encapsulating resin creates an inert protective environment around the solder joints and chip component terminals. This resin barrier prevents solder migration even when voltage is applied between terminals, thereby maintaining electrical functionality while preventing short-circuits between adjacent terminals.
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 solution effectively reduces the occurrence of lift phenomena and interfacial delamination, enhancing the reliability and humidity resistance of the module by maintaining a stable connection area and adhesiveness between components.
Implementation Method 1
an average linear thermal expansion coefficient α of the encapsulating resin calculated by the following Formula 1 is not less than 17×10−6/° C. and not more than 110×10−6/° C.: α={α1×(Tg−Tr)+α2×(Tp−Tg)}/(Tp−Tg) wherein α1 indicates a linear thermal expansion coefficient of the encapsulating resin obtained at a temperature lower than a glass transition temperature thereof; α2 indicates a linear thermal expansion coefficient of the encapsulating resin obtained at a temperature exceeding the glass transition temperature
Data Source
AI summary
The electronic component integrated module includes a wiring board; an electronic component provided on the wiring board; solder for electrically connecting the electronic component onto the wiring substrate; and an encapsulating resin for encapsulating the electronic component and the solder. The average linear thermal expansion coefficient α of the encapsulating resin, which is calculated by using the glass transition temperature of the encapsulating resin, a linear thermal expansion coefficient α1 obtained at a temperature lower than the glass transition temperature, a linear thermal expansion coefficient α2 obtained at a temperature exceeding the glass transition temperature, room temperature, and a peak temperature of reflow packaging of the electronic component integrated module, is not less than 17×10−6/° C. and not more than 110×10−6/° C.