PCB Through-Hole Conductor Void Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for filling through-holes in printed wiring boards with metal often result in voids due to the blocking of the narrowest portion by plating, especially when reinforcing materials protrude from the substrate, leading to incomplete filling and reduced mechanical connection strength.
Innovation Solution
A through-hole configuration with a first opening tapering from the first surface to the second and a second opening tapering from the second to the first, where the reinforcing material protrudes into the through-hole at their intersection, allowing for easier filling with a conductive material and reducing the occurrence of voids by ensuring the plating starts from the narrowest portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrolytic plating is performed to fill the through-hole, then the through-hole is filled with metal, but the narrowest portion is blocked by plating before it is filled, causing voids to occur
Solution Approach 1:
The patent applies preliminary action by forming the protruding portion of the reinforcing material to extend into the through-hole before the plating process. This pre-configured structure ensures that the narrowest portion remains unblocked during electrolytic plating, allowing metal to fill the through-hole completely from the narrowest point outward, thereby preventing void formation and ensuring reliable mechanical connection.
2Ease of manufacture
If the through-hole is formed with a narrowest portion to control plating flow, then plating can fill the through-hole, but the reinforcing material protruding from the wall surface blocks the narrowest portion
Solution Approach 1:
The patent applies local quality by creating a protruding portion of the reinforcing material at a specific location (the narrowest portion of the through-hole) with a controlled shape and size. This localized protrusion is designed to be smaller than the through-hole diameter at that section, allowing it to define the narrowest portion without completely blocking the path. The protruding portion's specific geometry ensures plating can flow around it while maintaining control over the filling process.
3Strength
If the protruding portion of reinforcing material is made larger to ensure structural integrity, then mechanical strength is improved, but the through-hole filling is blocked and voids occur
Solution Approach 1:
The patent applies parameter changes by precisely controlling the dimensions and shape parameters of the protruding portion. The protruding portion is designed with specific dimensional constraints (smaller than the through-hole diameter at its location) to balance two competing requirements: maintaining sufficient structural integrity of the substrate while leaving enough clearance for complete through-hole filling. This optimized parameter design ensures both strength and manufacturing precision are achieved simultaneously.
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 configuration enhances the mechanical connection strength between the substrate and the through-hole conductor, reduces void formation, and facilitates easier formation of conductive circuits by ensuring uniform plating across the substrate surfaces.
Implementation Method 1
electrolytic plating is performed to form plated-metal layer 803 by filling metal starting in the narrowest portion
Data Source
AI summary
A printed wiring board includes a substrate having a first surface, a second surface on the opposite side of the first surface and a through-hole extending between the first and second surfaces, a first conductive circuit formed on the first surface of the substrate, a second conductive circuit formed on the second surface of the substrate, and a through-hole conductor filling the through-hole and connecting the first and second conductive circuits. The through-hole has a first opening portion tapering from the first surface toward the second surface and a second opening portion tapering from the second surface toward the first surface. The substrate is made of a resin and a reinforcing material portion in the resin. The reinforcing material portion has a protruding portion protruding into the through-hole at the intersection of the first and second opening portions. The protruding portion encroaches into the through-hole conductor.