Substrate Through Hole Formation via Segmented Laser Ablation
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Solution Overview
Problem
The existing hole processing methods for substrates, particularly laser-based methods, face challenges in forming through holes with precise dimensions and high manufacturing yield due to differences in thermal conductivity and laser absorption rates between core and metal layers, leading to defects and reduced yield.
Innovation Solution
A method involving the formation of through holes in a substrate by irradiating a laser beam in a single direction from one surface to the other, followed by removing protruding metal layer portions and forming a plating layer on the inner surface of the holes, which reduces defects and improves yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser beam is irradiated in a direction from one surface to the other surface of a substrate to form a through hole, then the through hole is formed efficiently, but the core layer and metal layer may be partially separated at the interface due to differences in thermal conductivity and laser absorption rate
Solution Approach 1:
The through hole formation process is segmented into two separate steps: first forming a blind via hole from the first surface to a depth not reaching the second surface, then forming a plated trough hole from the second surface to connect with the blind via hole. This segmentation prevents excessive thermal concentration at the core-metal layer interface that causes separation, while still achieving complete through-hole formation.
Solution Approach 2:
The blind via hole is formed preliminarily before forming the plated trough hole. This preliminary action creates a partial through hole that stops before reaching the second surface, allowing subsequent plating and finishing operations to be performed without causing interface separation between the core layer and metal layer.
2Manufacturing precision
If a through hole is formed by laser processing from both surfaces of the substrate, then complete through holes are achieved, but the manufacturing yield decreases
Solution Approach 1:
Instead of forming the through hole entirely from the first surface or entirely from the second surface, the invention inverts the conventional approach by forming the final connection from the second surface upward to meet the preliminarily formed blind via hole. This inversion allows precise control of hole dimensions and reduces defects, improving manufacturing yield.
3Ease of manufacture
If the opening size of the core layer is increased due to laser processing, then the laser processing is effective, but the core layer and metal layer may be partially separated at the interface
Solution Approach 1:
The laser processing is segmented into two stages: first creating a blind via hole with controlled opening size that does not cause interface separation, then creating a plated trough hole from the opposite surface to complete the connection. This segmentation allows effective laser processing while maintaining precise interface alignment between core and metal layers.
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 shortens processing time, enhances precision, and reduces defects by ensuring consistent hole dimensions, thereby improving the manufacturing yield and reducing the size of connection pads required for high-density circuits.
Implementation Method 1
forming a through hole in a substrate only in one of a direction from a top surface to a bottom surface of the substrate or a direction from a bottom surface to a top surface of the substrate
Implementation Method 2
forming a plating layer on an inner surface of the substrate forming at least the through hole
Data Source
AI summary
A substrate including a through hole only in one of a direction from a top surface to a bottom surface of the substrate or a direction from a bottom surface to a top surface of the substrate, a protruding portion of a metal layer protruding toward the through hole being removed, and a plating layer on an inner surface of the substrate on at least the through hole.