Circuit Board Plating Regions Layout for Uniform Electroplating
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Solution Overview
Problem
In circuit board fabrication, uneven electroplating thickness on contact pads leads to defects such as assembly abnormalities and uneven loading, due to variations in current density across different-sized plating regions.
Innovation Solution
The layout of plating regions is arranged to ensure uniform current density by interconnecting smaller plating regions in a serial connection manner, with a solder mask covering the edges and exposing the plating regions for uniform electroplating, resulting in a uniform metal layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If plating regions of different sizes are used for contacts, then the circuit board can accommodate various contact requirements, but the current density becomes uneven leading to non-uniform plating thickness
Solution Approach 1:
The patent divides the plating regions into multiple groups and connects them through plating lines in a segmented manner. Smaller plating regions are connected in series through multiple plating lines, which segments the current path and distributes current density more evenly across all plating regions, thereby achieving uniform plating thickness while maintaining different contact sizes.
Solution Approach 2:
The patent designs the plating line connections to ensure that all plating regions, regardless of their size or position, are at the same electrical potential during electroplating. By strategically connecting plating lines between different plating regions, the patent equalizes the current density distribution, making sure each region receives appropriate current for uniform plating thickness.
2Manufacturing precision
If plating lines are added to connect plating regions, then current density uniformity improves, but the device complexity increases
Solution Approach 1:
The patent merges multiple plating lines into a unified connection structure that serves multiple plating regions simultaneously. By combining the functions of multiple plating lines into an integrated design, the patent reduces the overall complexity while still achieving uniform current distribution across all plating regions.
Solution Approach 2:
The plating lines are designed to serve multiple functions: they connect different plating regions, distribute current evenly, and maintain electrical potential equality across all contacts. This multi-functionality reduces the need for additional complex structures, simplifying the overall device while achieving the desired plating uniformity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves uniform plating thickness across contact pads, enhancing the quality and reliability of circuit boards by maintaining consistent current and voltage distribution during the electroplating process.
Implementation Method 1
contact pads can be formed on the conductive regions by an electroplating method
Implementation Method 2
a metal layer on the plating regions
Data Source
AI summary
A circuit board includes a substrate, a plurality of contacts disposed on a surface of the substrate, and a solder mask. The contacts have a plurality of plating regions and a metal layer on the plating regions, and the plating regions have at least two different sizes. The solder mask covers the surface of the substrate and covers edges of the plating regions, in which topmost surfaces of the contacts are below a top surface of the solder mask, and a gap between the topmost surfaces of the contacts and the top surface of the solder mask is larger than 0 μm and is smaller than 5 μm.