PCB Via Formation Using Metal Ball Intermediary
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Solution Overview
Problem
The challenge in manufacturing printed circuit boards with glass cores is the difficulty in forming seed layers within high-aspect-ratio through-holes due to the smooth glass surface, which requires a significant amount of time and cost using sputtering processes.
Innovation Solution
The solution involves forming through-holes with inclined walls in an insulating glass core layer, inserting a metal ball into the through-hole, and then using a sputtering process to form seed layers on both sides of the metal ball before performing fill plating to create a metal via surrounding the metal ball.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a through-hole with high aspect ratio is formed in a glass core, then the planarization and warpage properties are improved, but it becomes difficult to form a seed layer in the via hole
Solution Approach 1:
A metal ball is inserted into the through-hole before the sputtering process to serve as a preliminary seed structure. This metal ball provides a conductive base that facilitates subsequent seed layer formation through sputtering, solving the difficulty of forming seeds in high-aspect-ratio holes with smooth glass surfaces
Solution Approach 2:
The metal ball acts as an intermediary object between the glass substrate and the final metal via. It provides a conductive pathway and nucleation site that enables the sputtering process to deposit seed material effectively in otherwise difficult-to-access high-aspect-ratio through-holes
2Manufacturing precision
If a sputtering process is used to form a seed layer in a high aspect ratio via hole, then the seed layer can be formed, but it takes a significant amount of time and costs
Solution Approach 1:
The metal ball is pre-inserted into the through-hole to create an immediate conductive base, eliminating the need for prolonged sputtering to build up seed thickness from scratch. This preliminary structure allows the sputtering process to be completed more quickly and efficiently
Solution Approach 2:
The metal ball serves as a temporary sacrificial element that facilitates the sputtering process but can be removed afterward. This disposable component enables faster seed layer formation without the need for complex, time-consuming processes to achieve the desired seed thickness
3Manufacturing precision
If fill plating is performed on a through-hole with high aspect ratio, then the metal via can be formed, but voids or seams may form
Solution Approach 1:
The metal ball is inserted before fill plating to create a central conductive core. This preliminary structure serves as a nucleation site for metal deposition during fill plating, ensuring uniform metal growth from the center outward and preventing void formation in high-aspect-ratio through-holes
Solution Approach 2:
The metal ball acts as an intermediary structure during fill plating, providing a stable central core that guides uniform metal deposition. This intermediary presence ensures that metal layers deposit evenly from the center toward the walls, preventing seam formation and ensuring reliable via filling
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 effectively suppresses the formation of voids or seams during fill plating in high-aspect-ratio through-holes, improving substrate quality while minimizing the time and cost associated with the sputtering process.
Implementation Method 1
using a sputtering process to form seed layers on both sides of the metal ball
Implementation Method 2
perform fill plating to form a metal via surrounding a metal ball
Data Source
AI summary
The present disclosure relates to a printed circuit board including: an insulating layer, a through-hole penetrating the insulating layer from an upper surface to a lower surface of the insulating layer and having an inclined wall surface; a metal ball disposed within the through-hole and in contact with the inclined wall surface; and a metal via filling the through-hole and surrounding the metal ball.