Inductor External Terminal Bending Crack Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inductors with metallic magnetic powder and metal plates experience frequent cracks in the plating layer at bent portions, leading to poor solder wettability and soldering failures due to increased forces during bending, especially for smaller inductors.
Innovation Solution
The inductor design includes a main body with a metal body having a first metal portion buried inside and second metal portions extending outward, formed into tabular shapes with specific bends and curvature radii to minimize stress and prevent cracks, with the elongation percentage of the outer peripheral surface set to 13% or less to ensure reliable soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the metal plate is bent to form external terminals, then the inductor can be mounted on printed circuit boards, but cracks occur in the plating layer at bent portions
Solution Approach 1:
The patent applies parameter changes by precisely controlling the curvature radius of the bent portion and the elongation percentage of the plating layer. By setting the curvature radius to specific values and limiting the elongation percentage to 6% or less, the patent optimizes the bending parameters to prevent crack formation while maintaining mountability.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and pre-setting the curvature radius and elongation percentage before bending occurs. The design specifies exact geometric parameters in advance that ensure the plating layer will not crack during the bending process, preventing the problem before it occurs.
2Volume of moving object
If the inductor size is reduced, then the device becomes more compact, but bending forces increase causing more frequent cracks
Solution Approach 1:
The patent applies parameter changes by establishing specific geometric parameter relationships that scale with inductor size. The curvature radius is set as a proportion of the inductor dimensions, and the elongation percentage is controlled within specific ranges, allowing small inductors to maintain adequate bending radii and prevent cracks despite their compact size.
3Shape
If the plating layer is stretched during bending, then the external terminal is formed, but solder wettability deteriorates due to crack generation
Solution Approach 1:
The patent applies parameter changes by controlling the elongation percentage of the plating layer during bending. By limiting the elongation to 6% or less and setting specific curvature radii, the patent ensures that the plating layer forms the required external terminal shape without exceeding the strain threshold that would cause cracking and soldering failures.
Data Source
AI summary
An inductor includes a main body having a bottom surface, a top surface positioned opposite to the bottom surface, four side surfaces connected to the bottom surface and the top surface, a metal body that includes a first metal portion buried in the main body and second metal portions extending outward from respective opposite longitudinal ends of the first metal portion. The second metal portions are exposed from respective opposite side surfaces of the main body. In the inductor, each second metal portion is formed into a tabular shape having a first surface with a plating layer and a second surface positioned opposite to the first surface. Each second metal portion is formed into an external terminal and includes a first bend and a second bend that are formed by bending the second metal portion.