Stubless PCB Plating via Laser Seed Layer Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for manufacturing printed circuit boards (PCBs) result in extraneous copper stubs at the top and bottom of plated through-holes, which limit electrical performance, especially at high frequencies, and require time-consuming and costly backdrilling processes that can damage PCBs and reduce production yield.
Innovation Solution
A process involving laser ablation to remove the outermost portion of the seed layer from the interior surface of through-holes in PCBs, allowing for precise copper plating without forming copper stubs, thereby eliminating the need for backdrilling and minimizing damage to the PCBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plating process is used to form plated through-holes, then copper interconnects are formed, but extraneous copper stubs are created at the top and bottom of through-holes which limit electrical performance
Solution Approach 1:
The patent applies preliminary action by removing the outermost portion of the seed layer with a laser before applying the copper layer. This preliminary removal of the seed layer's outer portion prevents copper from depositing in the stub regions, thereby avoiding the formation of extraneous copper stubs that would otherwise limit electrical performance at high frequencies
Solution Approach 2:
The patent extracts or removes the outermost portion of the seed layer from the through-hole interior surfaces using laser ablation. This extraction eliminates the substrate that would otherwise support unwanted copper deposition in the stub regions, allowing clean copper plating only where needed while preventing harmful copper stub formation
2Reliability
If backdrilling process is used to remove copper stubs, then signal integrity is improved, but the process is time consuming and expensive
Solution Approach 1:
The patent performs the stub prevention action during the initial plating process by laser removal of the seed layer's outermost portion before copper deposition. This preliminary action eliminates the need for subsequent backdrilling operations, thereby maintaining signal integrity while significantly reducing fabrication time and increasing productivity
Solution Approach 2:
The patent converts what would normally be a harmful post-processing step (backdrilling to remove stubs) into a beneficial integrated process step. By incorporating laser seed layer removal into the plating process itself, the harmful separate backdrilling operation is eliminated, transforming the workflow from a multi-step harmful process to a single integrated beneficial process
3Manufacturing precision
If backdrilling is used to remove copper stubs, then stubs are removed, but PCBs are subjected to unnecessary damage reducing production yield
Solution Approach 1:
The patent extracts the outermost portion of the seed layer using laser ablation before copper plating, thereby preventing stub formation in the first place. This extraction approach eliminates the need for damaging backdrilling operations that would otherwise be required to remove stubs, thus maintaining production yield while achieving precise stub control
Solution Approach 2:
The patent converts the potentially harmful backdrilling process into a beneficial laser-based seed layer removal process that occurs during plating. This transformation eliminates mechanical damage to PCBs while achieving the same stub control objective, thereby maintaining high production yield
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 process enhances the precision and efficiency of copper plating, reduces production costs, and increases yield by eliminating copper stubs, allowing for higher performance PCBs with reduced damage and faster fabrication.
Implementation Method 1
A process involving laser ablation to remove the outermost portion of the seed layer from the interior surface of through-holes in PCBs
Data Source
AI summary
A process of copper plating a through-hole in a printed circuit board, and the printed circuit board made from such process. The process comprises: providing a printed circuit board with at least two copper interconnect lines separated by an insulator in the vertical direction; providing a through-hole in the printed circuit board in the vertical direction such that the interconnect lines provide a copper land in the through-hole; applying a seed layer to an interior surface of the through-hole; removing an outermost portion of the seed layer from the interior surface of the through-hole with a laser; applying copper on the seed layer.