PCB Edge Connector Pin Plating Without Tie Bars

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Solution Overview

Problem

Conventional methods for removing tie bars from gold fingers on printed circuit boards (PCBs) result in signal degradation due to residual material and metallic burrs, and chemical etching processes increase complexity and cost.

Innovation Solution

Forming edge connector pins by electrically coupling conductive layers via a bridging element, electroplating, and then removing the bridging element to separate the pins, eliminating the need for tie bars.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If beveling is used to remove tie bars, then mechanical material removal is achieved, but residual tie bar strips remain and metallic burrs are generated

Engineering Contradiction:

Improvetie bar removalVSAvoidsignal integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent extracts the harmful tie bar material completely from the PCB surface using chemical etching, rather than leaving residual strips as in beveling. The etching process removes all trace amounts of copper tie bar material, eliminating the source of signal degradation while maintaining manufacturing feasibility.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical beveling process with a chemical etching process. Instead of using mechanical abrasion that leaves residuals and burrs, the chemical etchant dissolves the copper tie bar material completely, substituting a chemical mechanism for a mechanical one to achieve cleaner removal.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If chemical etching is used to remove tie bars, then complete tie bar removal is achieved, but additional etching and cleaning processes are required

Engineering Contradiction:

Improvesignal integrityVSAvoidfabrication process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the tie bar removal function with the existing gold electroplating process. By applying the electroplating solution to the entire PCB surface including the copper tie bars, the process simultaneously deposits gold on the connector pins and removes the tie bars through etching, combining two functions into one process step.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The electroplating solution serves multiple functions: it deposits the protective gold layer on the connector pins and simultaneously acts as the etching agent to remove the copper tie bars. This multi-functional approach eliminates the need for separate etching and cleaning steps, reducing process complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If tie bars are used during gold electroplating, then electrical coupling between pins is achieved, but unwanted capacitance and signal reflection are created

Engineering Contradiction:

Improveelectroplating processVSAvoidsignal noise

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an intermediary substance - the electroplating solution - that facilitates the electroplating process without requiring physical tie bars. The solution allows electrical current to flow between pins during plating while the copper substrate serves as the bonding agent, eliminating the need for separate tie bar structures that create signal interference.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical state and properties of the bonding material from solid copper tie bars to a chemical solution state. By using the electroplating solution to deposit metal while the copper substrate provides electrical connection, the process achieves both bonding and electrical coupling without the harmful geometric constraints of solid tie bars.

Inventive Principle:

Principle #35Parameter changes

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 method maintains signal integrity by avoiding tie bar-related noise and eliminates the need for additional chemical etching and cleaning processes.

Implementation Method 1

electroplating a second conductive layer onto both the first conductive layer for the first edge connector pin and the first conductive layer for the second edge connector pin via a plating current conductor

Methodology Applied

Scientific EffectElectroplating: Electroplating

Data Source

PatentUS12484156B2Electroplating edge connector pins of printed circuit boards without using tie bars

Publication Date: 2025.11.25 NVIDIA CORP

AI summary

A method for forming a printed circuit board includes: forming on a substrate a first conductive layer for a first edge connector pin and a first conductive layer for a second edge connector pin, wherein the first conductive layer for the first edge connector pin and the first conductive layer for the second edge connector pin are electrically coupled to one another via a first conductive layer for an electrical bridging element; electroplating a second conductive layer onto both the first conductive layer for the first edge connector pin and the first conductive layer for the second edge connector pin via a plating current conductor; and removing at least a portion of the electrical bridging element to electrically separate the first edge connector pin from the second edge connector pin.