Glass-Core PCB Via Structure for Seed Adhesion and Fill Plating
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Solution Overview
Problem
Glass core substrates in printed circuit boards face issues with adhesion during seed metal layer formation and non-plating during fill plating in via holes, leading to warpage and via open defects.
Innovation Solution
A through-hole in the glass layer is filled with an insulating material, followed by forming a via hole in the insulating material and depositing multiple metal layers, including a seed layer conformally on the via hole walls to ensure adhesion and prevent non-plating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a via hole is formed directly in a glass layer, then the smooth surface of glass facilitates microcircuit implementation, but adhesion of seed metal layer cannot be secured
Solution Approach 1:
An insulating material is introduced as an intermediary substance between the glass layer and the metal via structure. The insulating material fills the through-hole in the glass layer, providing a suitable surface for seed metal layer formation while maintaining the glass layer's smooth exterior for microcircuit implementation.
2Reliability
If fill plating is performed in a via hole formed in glass layer, then via holes can be filled with plating, but non-plating occurs in central portion leading to via open defects
Solution Approach 1:
The insulating material serves as a mediator that modifies the via hole environment, enabling uniform plating deposition. By providing a non-glass surface within the via hole, it facilitates proper nucleation and growth of the metal layers during fill plating, preventing non-plating defects in the central portion.
Solution Approach 2:
The through-hole in the glass layer is pre-filled with insulating material before forming the via hole and performing fill plating. This preliminary action prepares the via hole structure with appropriate surface properties, ensuring successful subsequent metal layer deposition and preventing plating defects.
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
The solution secures adhesion of the seed metal layer and prevents non-plating, enhancing the reliability of the printed circuit board by improving coverage and reducing via open defects.
Implementation Method 1
a first metal layer in which at least a portion thereof is substantially conformally disposed on a wall surface of the via hole
Implementation Method 2
a second metal layer in which at least a portion thereof is substantially conformally disposed on the first metal layer
Implementation Method 3
a third metal layer disposed on the second metal layer and filling at least a portion of the via hole
Data Source
AI summary
A printed circuit board is provided. The printed circuit board includes a glass layer having a through-hole; an insulating material disposed within the through-hole and having a via hole; and a metal via disposed within the via hole. The metal via includes a first metal layer that is substantially conformally disposed on a wall surface of the via hole, a second metal layer that is substantially conformally disposed on the first metal layer, and a third metal layer disposed on the second metal layer and filling at least a portion of the via hole.