Circuit Module Case With Grooved Legs for Solder Flow
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Solution Overview
Problem
Existing circuit modules face displacement issues during mounting due to uneven solder distribution, which affects bonding strength and module size, as the design must be optimized for each module, leading to increased size and reduced bonding strength.
Innovation Solution
The circuit module incorporates a case with a top plate and legs that extend perpendicularly, featuring grooves on the end surfaces to facilitate even solder flow, reducing displacement and maintaining bonding strength by allowing solder to flow between both sides of the leg, thereby minimizing uneven solder distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the width of case lands is increased to provide sufficient bonding strength, then bonding strength is improved, but mounting position displacement increases
Solution Approach 1:
The case land is divided into two distinct regions: a narrow positioning portion (111a) and a wide bonding-strength securing portion (111b). This segmentation allows the positioning portion to maintain precise mounting alignment while the bonding portion provides sufficient area for strong solder bonding, thereby resolving the contradiction between bonding strength and mounting precision.
Solution Approach 2:
Different portions of the case land are given different widths to serve different functions. The positioning portion has a narrow width optimized for precise mounting alignment, while the bonding portion has a wide width optimized for strong solder bonding. This local differentiation allows each region to optimize its performance for its specific purpose.
2Strength
If the area of case lands is increased to increase bonding strength, then bonding strength is improved, but overall module size is increased
Solution Approach 1:
By segmenting the case land into positioning and bonding portions, the design achieves strong bonding through the wide bonding portion while keeping the overall case land area compact. The narrow positioning portion minimizes the area required for mounting precision, thus reducing overall module size while maintaining bonding strength.
3Manufacturing precision
If narrow positioning portions are used to prevent displacement, then mounting position precision is improved, but solder amount is reduced and bonding strength is decreased
Solution Approach 1:
The case land is segmented into a narrow positioning portion for precise mounting and a wide bonding portion for strong solder bonding. This segmentation resolves the contradiction by allowing the positioning portion to be narrow (for precision) while the bonding portion is wide (for strength), with both portions working together to achieve both goals simultaneously.
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 reduces case displacement and maintains bonding strength by ensuring even solder distribution, addressing the challenges of uneven solder distribution and module size optimization.
Implementation Method 1
the groove allows solder, which is melted by being heated in a reflow furnace, to flow between both sides of the end surface of the leg
Implementation Method 2
solder, which is melted by being heated in a reflow furnace
Data Source
AI summary
A circuit module includes a substrate, a component land provided on the substrate, an electronic component bonded to the component land, a case land provided on the substrate, and a case bonded to the case land so as to cover the electronic component. The case includes a top plate, and a leg that extends from a peripheral edge of the top plate in a direction substantially perpendicular to the top plate and that includes a groove in an end surface thereof that is bonded to the case land.