Fine-Pitch Wiring Substrate Layout for High-Frequency Signal Integrity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wiring substrates face challenges in achieving high-density wiring with reduced defects and improved signal transmission quality, particularly in high-frequency applications, due to limitations in wiring width, inter-wiring distance, and aspect ratio.
Innovation Solution
A dual-layer wiring substrate design with finer conductor layers and via conductors, where the second wiring substrate has minimum wiring widths and inter-wiring distances of 3 μm or less and aspect ratios between 2.0 and 4.0, utilizing insulating layers with low relative permittivity and dielectric loss tangent, and incorporating small inorganic filler particles to minimize short circuits and ensure uniform conductor layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wiring width and inter-wiring distance are reduced to increase wiring density, then wiring density is improved, but manufacturing precision and reliability deteriorate due to difficulty in forming fine patterns and maintaining uniform thickness
Solution Approach 1:
The patent changes the aspect ratio parameter of the conductor layer to be 2.0 or more, which optimizes the relationship between wiring width and thickness. This parameter change enables fine wiring patterns to be formed while maintaining sufficient thickness uniformity and manufacturing feasibility, thus resolving the contradiction between high wiring density and manufacturing precision
Solution Approach 2:
The patent applies preliminary protective measures by forming a plating layer on the conductor layer before mounting the wiring substrate. This preliminary action prevents oxidation and corrosion of the fine conductor patterns, ensuring their reliability during subsequent manufacturing processes and preventing defects that would otherwise occur with reduced wiring dimensions
2Productivity
If aspect ratio of conductor layers is increased to reduce wiring width, then wiring density is improved, but reliability deteriorates due to increased risk of discontinuity and manufacturing difficulty
Solution Approach 1:
The patent optimizes the aspect ratio parameter to be 2.0 or more, which strikes a balance between achieving fine wiring patterns and maintaining conductor layer reliability. This parameter optimization ensures that the conductor layers remain continuous and manufacturable while enabling high wiring density
Solution Approach 2:
The patent uses composite material structure with a conductor layer (copper or copper alloy) combined with a plating layer (nickel, palladium, or gold). This composite structure enhances the reliability of the fine conductor patterns by providing mechanical strength and corrosion resistance, preventing discontinuity issues that would occur with thin conductor layers alone
3Productivity
If wiring dimensions are reduced for high-density wiring, then wiring density is improved, but signal transmission quality deteriorates due to increased susceptibility to interference and defects
Solution Approach 1:
The patent employs a composite material system consisting of conductor layer, plating layer, and insulating layer with specific dielectric properties. This composite structure provides electromagnetic shielding and reduces crosstalk between fine wiring patterns, maintaining signal transmission quality while achieving high wiring density
Solution Approach 2:
The patent specifies that the insulating layer has a relative permittivity of 3.5 or less and a dielectric loss tangent of 0.005 or less at 1 GHz. These parameter changes in the insulating material reduce signal loss and interference in fine wiring patterns, ensuring high-quality signal transmission in high-density configurations
Data Source
AI summary
A wiring substrate includes a first wiring substrate including first insulating layers, first conductor layers, and first via conductors, and a second wiring substrate mounted on the first substrate and including second insulating layers, second conductor layers, and second via conductors. The second substrate is formed such that the minimum wiring width of wirings in the second conductor layers is smaller than the minimum wiring width of wirings in the first conductor layers, the minimum inter-wiring distance of the wirings in the second conductor layers is smaller than the minimum inter-wiring distance of the wirings in the first conductor layers, the wiring widths of the wirings in the second conductor layers are 3 μm or less, the inter-wiring distances of the wirings in the second conductor layer are 3 μm or less, and aspect ratio of the wirings in the second conductor layer is in range of 2.0 to 4.0.