Surface-Mount Coil Component Via Hole Relocation
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Solution Overview
Problem
Existing common mode filters face challenges in reducing size while maintaining high impedance characteristics due to the need for via holes that occupy more space than the coil conductors, limiting the number of coil turns and magnetic surface area.
Innovation Solution
A coil component design featuring spiral coil conductors with cut ends connected by bridge conductors through insulation films, eliminating the need for via holes within the coil conductors, allowing for a larger magnetic layer and increased impedance without increasing the size of the filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If via holes are formed inside coil conductors to connect lead-out electrodes, then electrical connection between coil conductors and lead-out electrodes is improved, but the area occupied by via holes increases, reducing the number of coil turns and magnetic layer area
Solution Approach 1:
The patent moves the via holes from the planar dimension (inside the coil conductor area) to the vertical dimension (outside the coil conductor area, connecting to side surfaces). This dimensional transition allows electrical connection without occupying precious planar area, enabling larger magnetic layer area and more coil turns.
Solution Approach 2:
The patent divides the connection function into separate components: lead-out electrodes are positioned outside the coil conductor and connect to side surfaces through via holes, rather than requiring integrated connection points within the coil conductor area. This segmentation frees up the coil conductor area for additional turns and magnetic layer expansion.
2Reliability
If the number of coil turns is increased to improve impedance characteristics, then common mode impedance increases, but the area required for coil conductors and via holes increases, limiting size reduction
Solution Approach 1:
By relocating via holes to the vertical dimension (outside coil conductors), the patent frees up planar area that can be used for increasing the number of coil turns without proportionally increasing the total component area, thus improving impedance characteristics while maintaining size constraints.
Solution Approach 2:
The patent nests the magnetic layer within the coil conductor structure, maximizing the use of available area for magnetic material. The via holes are positioned to connect to the nested structure from the outside, allowing the magnetic layer to occupy maximum area for enhanced inductance and impedance.
3Manufacturing precision
If photolithographic process is used to form small via holes for size reduction, then manufacturing precision is improved, but via holes are still formed greater than coil conductor width, requiring separate connecting regions
Solution Approach 1:
The patent extracts the via hole connection function from the coil conductor interior to the exterior, connecting to side surfaces rather than requiring via holes inside the coil conductor area. This extraction eliminates the need for separate connecting regions within the coil area, simplifying the overall structure despite using photolithographic processes.
Data Source
AI summary
The invention relates to surface-mount type coil components having a mounting surface for mounting them on a printed circuit board or hybrid IC (HIC) and provides a coil component having high electrical characteristics. A common mode filter includes a coil conductor formed in a spiral shape, cut ends which are parts of the coil conductor cut to face each other, and bridge conductors formed so that an insulation film is interposed between the coil conductor and the same to connect the cut ends to each other.