Trenched Substrate Design for Solder Joint Durability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Surface-mounted capacitors on electronic substrates experience significant thermomechanical strain due to mismatched coefficients of thermal expansion, leading to solder joint fatigue and cracks, which reduces the lifespan of electronic packages during thermal cycling.
Innovation Solution
Forming trenches on the substrate surface reduces its stiffness, thereby minimizing shear stress on solder joints and enhancing joint durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitors are mounted on a substrate using conventional methods, then the electronic module can be assembled, but significant thermomechanical strain occurs during thermal cycling causing solder joint fatigue and cracks
Solution Approach 1:
The substrate is designed with non-uniform mechanical properties through the formation of trenches or relaxed regions at specific locations beneath the capacitor. These localized modifications create areas of reduced stiffness that accommodate thermal expansion differences, thereby protecting the solder joints from thermomechanical strain while maintaining the overall structural integrity of the substrate.
Solution Approach 2:
The mechanical parameters of the substrate are changed by introducing trenches or relaxed regions that alter the stiffness distribution. This parameter modification allows the substrate to better accommodate thermal expansion mismatches between the capacitor and substrate, reducing the thermomechanical strain on solder joints during thermal cycling.
2Strength
If the substrate stiffness is high, then structural support is strong, but shear stress on solder joints increases during thermal cycling
Solution Approach 1:
The substrate exhibits spatially varying mechanical properties with stiff regions providing overall structural support and localized relaxed regions (trenches) beneath the capacitor that reduce shear stress on solder joints. This local quality differentiation allows the substrate to simultaneously maintain strong structural support while minimizing stress on critical joints.
Solution Approach 2:
The substrate is effectively segmented into different mechanical zones: stiff support regions and relaxed regions with trenches. This segmentation allows different parts of the substrate to perform different functions - providing structural support where needed and reducing stress on solder joints in critical areas.
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 trench design reduces stress on solder joints by 18%, thereby extending the life of the joints and improving the robustness of the electronic package under thermal cycling.
Implementation Method 1
The trench design reduces stress on solder joints by 18%, thereby extending the life of the joints and improving the robustness of the electronic package under thermal cycling
Data Source
AI summary
An electronic module includes a substrate including at least one structure that reduces stress flow through the substrate, wherein the structure includes at least one trench in a surface of the substrate, and a plurality of capacitor legs disposed on an upper surface of the substrate.