Polygonal Core Insertion Hole for DC-DC Converter Short-Circuit Prevention
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Solution Overview
Problem
The challenge is to prevent short-circuiting between a core and edge-face through-holes in DC-DC converters, where the formation of edge-face through-holes on curved inner wall surfaces of core insertion holes can lead to burrs and increased likelihood of short-circuiting, while also reducing the available board surface area for electronic component mounting.
Innovation Solution
A multilayer board with a polygonal core insertion hole and edge-face through-holes formed in concave portions on the inner wall surfaces, which are positioned away from the core's outer surface, preventing direct contact and reducing the risk of short-circuiting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If edge-face through-holes are formed on the inner wall surfaces of the core insertion hole to electrically connect coil wiring patterns, then the available board surface area for electronic component mounting is increased, but burrs may arise during hole formation and short-circuiting between the core and through-holes may occur
Solution Approach 1:
The core insertion hole is given a polygonal shape instead of a circular shape, creating asymmetric flat regions on the inner wall surface. This asymmetric geometry allows edge-face through-holes to be formed in specific locations that are optimized for both electrical connection and avoidance of burr-induced short-circuiting, while maximizing the remaining surface area for component mounting.
Solution Approach 2:
The polygonal shape with flat regions is designed in advance during the board fabrication process, before the core is inserted and before through-holes are formed. This preliminary structuring of the insertion hole geometry ensures that subsequent through-hole formation occurs in predetermined safe zones, preventing short-circuiting while maximizing mounting area.
2Reliability
If through-hole wirings are formed in regions where electronic components are to be mounted to connect coil wiring patterns, then electrical connection between layers is achieved, but the area available for mounting electronic components decreases
Solution Approach 1:
The electrical connection between coil wiring patterns is moved from the board surface plane to the vertical dimension by forming edge-face through-holes on the inner wall surfaces of the core insertion hole. This dimensional transition allows through-holes to be positioned in the thickness direction rather than occupying valuable surface area, enabling both electrical connection and maximum component mounting area.
Solution Approach 2:
The through-hole connections are extracted from the component mounting region and relocated to the inner wall surfaces of the core insertion hole. This extraction separates the electrical connection function from the component mounting function, allowing each to be optimized independently without compromising the other.
3Shape
If a circular core insertion hole is used, then the inner wall surface is curved and conformal to the core shape, but burrs are liable to arise during edge-face through-hole formation and short-circuiting is more likely to occur
Solution Approach 1:
The circular symmetric shape is replaced with a polygonal asymmetric shape that includes flat regions. These flat regions provide stable, burr-free surfaces for through-hole formation, eliminating the curved surface problems associated with circular holes while maintaining adequate conformality to the core through the overall polygonal geometry.
Solution Approach 2:
Different regions of the core insertion hole inner wall are given different geometrical qualities: flat regions are provided specifically for through-hole formation to prevent burrs, while other regions maintain curvature for core conformality. This local differentiation of geometric properties optimizes both manufacturing precision and functional performance.
Data Source
AI summary
An electronic module is provided with a circuit board including a central-axis insertion hole and composed by laminating a multitude of wiring layers; and a core formed of a magnetic material and inserted through the central-axis insertion hole, wherein the circuit board includes a plurality of coil wiring patterns formed in positions of the respective wiring layers surrounding the core insertion hole; and edge-face through-holes formed on inner wall surfaces of the central-axis core insertion hole to electrically connect the plurality of coil wiring patterns to form a coil, the central-axis insertion hole has a octagon shape in plan view, concave portions are disposed on the inner wall surfaces corresponding to sides of the octagon shape, and the edge-face through-holes are formed in the concave portions.