Circuit Board Dummy Pattern for Flat Surface Reflow
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Solution Overview
Problem
Existing circuit boards with protruding wiring patterns lead to uneven surfaces during the reflow process, causing unreliable bonding of devices and potential deformation, which affects the reliability and efficiency of device mounting and heat dissipation.
Innovation Solution
A circuit board design incorporating a dummy pattern in the device mount area, which is filled with a conductive material and extends outward from the bonding portion, along with a lead pattern and connection wiring, to create a flat surface and improve heat dissipation, ensuring reliable device mounting and reducing surface unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wiring patterns are formed to connect devices, then electrical connectivity is achieved, but the surface becomes uneven causing unreliable bonding
Solution Approach 1:
The patent creates a dummy pattern that copies the shape and size of the device to be mounted, filling the device mount area. This dummy pattern serves as a template or model that allows the protective layer to be formed flat, solving the surface unevenness problem caused by the actual wiring patterns while maintaining the electrical connectivity function through separate lead patterns.
Solution Approach 2:
The dummy pattern acts as an intermediary element between the wiring patterns and the protective layer. It provides a flat surface foundation for the protective layer while being electrically isolated from the wiring patterns, thus mediating the conflict between electrical connectivity and surface flatness.
2Strength
If the protective layer covers protruding wiring patterns, then protection is provided, but the surface remains uneven affecting device mounting
Solution Approach 1:
The dummy pattern is designed to match the device dimensions and fills the mount area, providing a uniform surface that allows the protective layer to be formed flat and evenly, eliminating the unevenness caused by protruding wiring patterns while maintaining protective coverage.
3Reliability
If lead patterns follow the uneven surface, then connection is maintained, but bonding reliability decreases
Solution Approach 1:
The dummy pattern provides a flat reference surface that enables the lead patterns to be formed with proper geometry and spacing, ensuring reliable bonding surfaces for devices during the reflow process while simplifying the manufacturing process.
Solution Approach 2:
The dummy pattern is formed in advance during the wiring pattern formation process, establishing a flat surface foundation before the protective layer and lead patterns are created, thereby preventing surface unevenness from affecting subsequent bonding operations.
Data Source
AI summary
Disclosed herein are a circuit board and a method of fabricating the same. The circuit board includes: a base substrate having a device mount area defined thereon; a first wiring pattern formed on a first surface of the base substrate; a dummy pattern formed on the base substrate, wherein at least a part of the device mount area is filled with the dummy pattern; a first protective layer covering the first wiring pattern and the dummy pattern; and a lead pattern formed on the first protective layer, wherein the lead pattern is extended to the device mount area.