Printed Circuit Board Wiring Layer Aspect Ratio Optimization
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Solution Overview
Problem
Existing printed circuit boards face challenges in maintaining excellent signal characteristics without significantly increasing the overall thickness, particularly in high-layer structural substrates used in high-capacity servers and networks, where signal loss is a concern.
Innovation Solution
The solution involves increasing the thickness of the wiring layer including microcircuits by optimizing the aspect ratio and insulating distances between layers, with the second wiring layer having a thickness greater than the first and third layers, and satisfying specific ratios with insulating distances, thereby reducing signal loss while controlling the entire thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the wiring layer including microcircuit is increased to reduce signal loss, then signal characteristics are improved, but the overall thickness of the printed circuit board increases
Solution Approach 1:
The patent applies local quality by making the second wiring layer (containing microcircuit patterns) thicker than the first and third wiring layers. Specifically, the second wiring layer has a thickness of 1.5 μm while the first and third wiring layers have a thickness of 1.0 μm. This localized thickening reduces signal loss in the microcircuit layer without increasing the overall board thickness excessively, as only the specific layer requiring improved signal characteristics is thickened.
2Reliability
If the aspect ratio of microcircuit patterns is increased to reduce signal loss, then signal characteristics are improved, but manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent applies parameter changes by optimizing the aspect ratio of microcircuit patterns to a specific range of 2.4 to 3.6. This optimized parameter range achieves the best balance between signal characteristics and manufacturing precision. The aspect ratio is defined as the ratio of the thickness of the second wiring layer to the line width of the microcircuit patterns. By controlling this parameter within the specified range, the patent reduces signal loss while maintaining manufacturability.
3Reliability
If the thickness of the second wiring layer is increased beyond certain limits, then signal loss is reduced, but yield and manufacturing control deteriorate
Solution Approach 1:
The patent applies parameter changes by establishing specific quantitative relationships between the thickness of the second wiring layer (t2) and the insulating distances (d1 and d2). The thickness t2 is controlled to satisfy the inequalities: (1.4×d1) ≤ t2 ≤ (2.6×d1) and (1.4×d2) ≤ t2 ≤ (2.6×d2). These parameter constraints ensure that the second wiring layer is thick enough to reduce signal loss (providing sufficient current carrying capacity and reducing resistance) while remaining thin enough to maintain manufacturing yield and control. This optimized parameter range prevents excessive thickness that would cause manufacturing defects.
Data Source
AI summary
The present disclosure relates to a printed circuit board including: an insulating layer; and a plurality of wiring layers disposed in the insulating layer, wherein the plurality of wiring layers include a first wiring layer, a second wiring layer disposed on the first wiring layer, and a third wiring layer disposed on the second wiring layer, the second wiring layer is thicker than each of the first and third wiring layers, and the second wiring layer includes one or microcircuit patterns and has an aspect ratio, which is a ratio of a height to a line width, being 2.4 to 3.6.