Through-Electrode Circuit Board Structure to Eliminate Dimple Regions
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Solution Overview
Problem
The challenge is to create a circuit board with a large-area through electrode that minimizes dimple regions and surface stains, while simplifying the plating process to improve product reliability and yield.
Innovation Solution
The circuit board design includes a through electrode structure with a first metal layer having a concave upper surface and a second metal layer with a convex lower surface, where the height difference between the convex lower surface of the second metal layer and the lower surface of the insulating layer is less than the height difference between the upper surface of the insulating layer and its lower surface. This structure allows for a minimal plating process that fills the through hole effectively, preventing dimple regions and surface stains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-diameter through-hole is filled with metal material to form a large-area through electrode, then heat dissipation characteristics and shielding characteristics are improved, but it is not easy to fill the inside of the through-hole completely, resulting in dimple regions
Solution Approach 1:
The through electrode is divided into multiple metal layers (first metal layer, second metal layer, third metal layer) with different functions. The first metal layer provides base filling, the second metal layer fills the dimple region, and the third metal layer provides the surface electrode function. This segmentation allows each layer to be optimized for its specific purpose, ensuring complete filling while maintaining manufacturing feasibility.
Solution Approach 2:
The first metal layer is formed preliminarily to provide a base structure and partial filling of the through-hole before the second metal layer is applied. This preliminary action creates a foundation that reduces the complexity of subsequent filling operations and ensures better overall filling completeness.
2Ease of manufacture
If a conventional large-area through electrode with a dimple region is used, then the through-hole can be processed, but the dimple region affects through-hole processing during additional lamination, thereby affecting the reliability of the printed circuit board
Solution Approach 1:
The through electrode is segmented into multiple metal layers where the second metal layer specifically addresses the dimple region issue. By separating the filling function (second metal layer) from the electrode function (third metal layer), the structure eliminates the harmful dimple region that would otherwise interfere with subsequent lamination processes while maintaining ease of manufacture.
Solution Approach 2:
The invention converts the potential harm of an incomplete fill into a benefit by using the multi-layer structure. The second metal layer is specifically designed to fill the dimple region that would normally be problematic, transforming what was a manufacturing defect into a feature that ensures both ease of processing and high reliability.
3Manufacturing precision
If multiple plating processes are used to fill the through-hole completely, then dimple regions can be removed, but the plating process becomes complex and time-consuming
Solution Approach 1:
The plating process is segmented into three distinct metal layer formations, each with specific purposes. This segmentation allows for systematic control of the plating parameters (current density, plating time, solution composition) for each layer, making the complex process more manageable and controllable while achieving complete filling without excessive complexity.
Solution Approach 2:
Different plating parameters (current density, plating time, solution composition) are used for each metal layer formation. The first metal layer uses one set of parameters optimized for base filling, the second metal layer uses different parameters optimized for dimple region filling, and the third metal layer uses parameters optimized for surface electrode formation. This parameter optimization reduces overall process complexity by making each step more efficient.
4Reliability
If the through-hole is filled completely to eliminate dimple regions, then reliability is improved, but the plating process time increases, reducing productivity
Solution Approach 1:
The filling process is segmented into multiple stages with different metal layers, allowing parallel optimization of filling completeness and process time. Each layer can be plated with optimized parameters for its specific function, ensuring complete filling (improving reliability) while minimizing the total plating time (maintaining productivity).
Solution Approach 2:
By changing plating parameters (current density, time, solution composition) for each metal layer, the process achieves complete filling more efficiently. The first metal layer uses parameters optimized for rapid base filling, the second metal layer uses parameters optimized for precise dimple region filling, and the third metal layer uses parameters optimized for thin surface electrode formation, thereby reducing total process time while ensuring complete 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 design enhances product reliability by preventing dimple regions in the through electrode and first electrode part, improves customer satisfaction by eliminating surface stains, and simplifies the plating process, thereby increasing product yield.
Implementation Method 1
a first metal layer passing through upper and lower surfaces of the insulating layer; and a second metal layer disposed on the first metal layer
Data Source
AI summary
A circuit board according to an embodiment includes an insulating layer; a first metal layer passing through upper and lower surfaces of the insulating layer; and a second metal layer disposed on the first metal layer; wherein the first metal layer includes a concave upper surface and a lower surface, wherein the second metal layer includes a convex lower surface corresponding to the concave upper surface of the first metal layer, and wherein a first height between the convex lower surface of the second metal layer and the lower surface of the insulating layer is smaller than a second height between the upper surface of the insulating layer and the lower surface of the insulating layer.