Wiring Substrate Conductor-Film Ratio for Reduced Via Defects
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Solution Overview
Problem
Existing methods for manufacturing wiring substrates face challenges in forming via conductors with deep through holes, leading to defects such as voids and recesses, which affect the reliability and connectivity of the conductor layers.
Innovation Solution
The conductor film is formed with a specific thickness to ensure a ratio of 0.4 to 0.7 between the upper surface of the conductor film and the via conductor, allowing for the formation of via conductors with reduced depth and minimizing defects, thereby enhancing connectivity and reducing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If via conductors with deep through holes are formed in existing methods, then connectivity between conductor layers is achieved, but defects such as voids and recesses occur affecting reliability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the conductor film thickness to satisfy the inequality 0.4 ≤ t/(t+d) < 0.7, where t is conductor film thickness and d is via conductor depth. This parameter control optimizes the via conductor formation process, reducing voids and recesses while maintaining reliable connectivity between conductor layers.
2Manufacturing precision
If conductor film thickness is increased to reduce via conductor depth, then manufacturing precision improves, but the ratio relationship between conductor film and via conductor dimensions must be precisely maintained
Solution Approach 1:
The patent establishes a specific parameter relationship 0.4 ≤ t/(t+d) < 0.7 that guides the conductor film thickness selection. This parameter specification simplifies process control by providing clear design criteria, eliminating the need for complex iterative adjustments while achieving optimal via conductor formation with reduced depth and fewer 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
This approach results in a high-quality wiring substrate with fewer defects and improved connectivity, ensuring reliable electrical connections through the use of conductor films with controlled thickness and diameter.
Implementation Method 1
applying electrolytic plating on at least the portion of the upper surface of the via land such that a conductor film is formed on at least the portion of the upper surface of the via land of the conductor layer
Data Source
AI summary
A wiring substrate includes a conductor layer including a via land, a conductor film formed on the via land of the conductor layer, an insulating layer covering the conductor layer and the conductor film formed on the via land, and a via conductor formed in the insulating layer such that the via conductor is penetrating through the insulating layer and is connecting to the via land via the conductor film. A ratio of the shortest distance between an upper surface of the conductor film and an end surface of the via conductor on the opposite side with respect to an end surface connected to the conductor film to the shortest distance between an upper surface of the via land and the end surface of the via conductor on the opposite side with respect to the end surface connected to the conductor film is in the range of 0.4 to 0.7.