Inductor External Electrode Flash Suppression
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Solution Overview
Problem
Conventional microminiature power converters experience flash generation and solder bridge formation due to wide external electrodes during the cutting process, leading to short-circuits and reliability issues.
Innovation Solution
The design features external electrodes with a smaller cross-sectional area at the peripheral edge of the ferrite substrate compared to the interior, and a method of forming through-holes and connection conductors to connect these electrodes, ensuring the electrodes' width or thickness is reduced at the cutting line to prevent flash generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of external electrodes is increased to improve electrical connection, then the electrical conductivity is improved, but flash generation occurs during cutting leading to solder bridge formation and short-circuits
Solution Approach 1:
The external electrode is designed with different widths at different locations: a first width in the region not subjected to cutting and a second width (narrower than the first width) in the region subjected to cutting. This local variation in geometry allows the electrode to maintain good electrical connection where needed while minimizing flash generation at the cutting line, thereby resolving the contradiction between electrical connection reliability and flash generation.
2Reliability
If the external electrode extends to the edge of ferrite substrate to improve electrical contact area, then the electrical conductivity is improved, but flash generation occurs at the cutting line
Solution Approach 1:
The external electrode features a first width in the non-cutting region and a second width (narrower than the first width) in the cutting region. This local geometric variation allows the electrode to maintain sufficient contact area for reliable electrical connection while presenting a narrower profile at the cutting line, thereby reducing flash generation and improving cutting precision without sacrificing overall electrical contact quality.
3Object-generated harmful factors
If the external electrode width is reduced at the cutting line to prevent flash generation, then flash generation is suppressed, but the electrical connection area is reduced
Solution Approach 1:
The external electrode is designed with a first width in the non-cutting region and a second width (narrower than the first width) in the cutting region. This local variation ensures that the electrode maintains sufficient width in the non-cutting region to provide reliable electrical connection area, while the narrower width at the cutting region suppresses flash generation during the cutting process, thereby resolving the contradiction between flash suppression and electrical connection area.
Data Source
AI summary
An inductor and a method of manufacture results in external electrodes that prevent generation of flashes. The inductor has a ferrite substrate, external electrodes, and a coil. The cross-sectional area of the external electrodes extending across the cutting line is reduced to suppress generation of flashes during the cutting process. Pairs of through-holes are formed at positions in line symmetry about the cutting line. A connection conductor is formed in each of the through-holes, and the external electrodes are formed on the front and back surfaces of the substrate, with the connection conductor connecting each of the pairs of external electrodes on the front and back surfaces. Through-holes can be oblong holes extending across the cutting line, and the external electrodes can extend away from the cutting line.