PCB Edge Connector Plating Without Tie Bar Stubs
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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 require additional chemical etching and cleaning processes, increasing complexity and cost.
Innovation Solution
A method of forming edge connector pins on PCBs by electrically coupling conductive layers via a bridging element, electroplating a second conductive layer, and then separating these layers to eliminate tie bar stubs without chemical etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If beveling processes are used to remove tie bars, then some material removal is achieved, but residual strips remain and deep cuts into PCB are required
Solution Approach 1:
The patent applies preliminary action by forming a sacrificial tie bar structure during the electroplating process itself, before final PCB assembly. The tie bar is intentionally created as a temporary feature that facilitates uniform gold plating across multiple connector pins, then removed in a controlled manner afterward without requiring deep PCB cuts or leaving harmful residuals.
Solution Approach 2:
The patent implements the extraction principle by completely removing the tie bar structure after it has served its plating function. The tie bar is extracted as a separate removable component rather than being permanently embedded in the PCB, allowing complete removal without damaging the PCB substrate or leaving residual strips that would compromise signal integrity.
2Manufacturing precision
If chemical etching processes are used to remove tie bars, then complete removal is achieved, but additional etching and cleaning processes are required
Solution Approach 1:
The patent applies the disposable principle by designing the tie bar as a temporary, sacrificial structure made of removable material. The tie bar serves its purpose during electroplating and is then completely removed without requiring complex chemical etching or cleaning processes. This temporary structure approach eliminates the need for additional fabrication steps while achieving complete tie bar removal.
Solution Approach 2:
The patent replaces chemical etching processes with a mechanical removal approach. Instead of using chemical etchants to dissolve the tie bar, the invention uses mechanical means such as drilling or routing to physically remove the tie bar structure after plating. This substitution eliminates the need for additional chemical processing steps and cleaning operations.
3Manufacturing precision
If beveling is used for tie bar removal, then material is removed from surface, but metallic burrs are generated that can cause electrical short
Solution Approach 1:
The patent extracts the tie bar as a completely separate removable component rather than attempting to blend it into the PCB surface through beveling. By designing the tie bar as a distinct structure that can be fully extracted through drilling or routing, the invention eliminates the generation of metallic burrs that would otherwise remain embedded in the PCB surface and potentially cause electrical shorts.
Solution Approach 2:
The patent replaces the surface-level mechanical beveling process with a different mechanical removal method that extracts the tie bar entirely. Instead of using beveling tools that scrape and generate burrs, the invention employs drilling or routing operations that cleanly remove the tie bar structure without leaving harmful metallic fragments on the PCB surface.
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 maintains signal integrity by eliminating tie bar-related noise and avoids additional chemical etching processes, simplifying the fabrication process and reducing costs.
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
Data Source
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.