PCB Copper Thickness Zoning for High Current and Soldering

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Solution Overview

Problem

Existing printed circuit boards (PCBs) face issues with low soldering temperatures and poor soldering effects due to increased copper foil thickness, which improves through-current capability but leads to heat absorption and inadequate soldering performance.

Innovation Solution

The PCB design includes a gold finger area with thicker conducting layers than the soldering area, maintaining overall board thickness consistency, ensuring sufficient soldering temperature and good soldering effects while reducing resistance and improving through-current capability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the thickness and area of copper foil are increased to reduce resistance and improve through-current capability, then the resistance of the gold finger area is reduced, but the copper foil absorbs a large amount of heat during soldering, resulting in low soldering temperature and poor soldering effect

Engineering Contradiction:
Improvethrough-current capabilityVSAvoidsoldering temperature
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent applies different copper foil thicknesses to different functional areas of the PCB. The gold finger area uses thicker copper foil (4-20 oz) to reduce resistance and improve through-current capability, while the soldering area uses thinner copper foil (1/3-3 oz) to minimize heat absorption and maintain adequate soldering temperature. This local differentiation resolves the contradiction by optimizing each area for its specific function.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The PCB is segmented into distinct functional zones with different copper foil specifications. The board is divided into a gold finger area and a soldering area, each with independently optimized copper thickness. This segmentation allows the thick copper needed for high current carrying capacity in the gold finger region without compromising the thermal characteristics required for proper soldering in the component mounting region.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the total thickness of conducting layers in the gold finger area is increased to reduce resistance, then the through-current capability is improved, but the overall board thickness consistency may be compromised, affecting surface smoothness and gold finger insertion

Engineering Contradiction:
Improvethrough-current capabilityVSAvoidsurface smoothness
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The patent implements local quality by varying copper foil thickness only in specific areas where functional requirements demand it. The thicker copper (4-20 oz) is applied exclusively to the gold finger area where high current capacity is needed, while the soldering area maintains thinner copper (1/3-3 oz). This localized approach allows the gold finger region to achieve superior electrical performance without causing excessive overall board thickness variation, as the thick copper is confined to a specific functional zone rather than the entire board.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3817521B1Printed circuit board, power supply, and power supply system
Publication Date: 2026.03.04 HUAWEI TECH CO LTD
  • EP3817521B1 patent drawingFigure 1~2
  • EP3817521B1 patent drawingFigure 3~4
  • EP3817521B1 patent drawingFigure 5~6

AI summary

This application provides a printed circuit board, a power supply, and a power supply system, and relates to a field of electronic communications technologies. The printed circuit board includes a first outer conducting layer, a second outer conducting layer, and at least one insulation medium layer sandwiched between the first outer conducting layer and the second outer conducting layer. The printed circuit board includes a gold finger area and a soldering area. A total thickness of all conducting layers in the gold finger area is greater than a total thickness of all conducting layers in the soldering area. Because the total thickness of all conducting layers in the gold finger area is set to be relatively thick, resistance of the gold finger area can be reduced, and a through-current capability of the gold finger area is improved. In addition, the total thickness of all conducting layers in the soldering area is set to be relatively thin, so that a sufficient soldering temperature and a good soldering effect can be ensured when electronic parts and components are soldered to the soldering area.