Laminated PCB Unit With Resin Isolation for Signal Integrity
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Solution Overview
Problem
Current printed circuit boards face challenges in high-speed and high-frequency signal transmission due to signal integrity issues, such as skew distortion and electromagnetic interference, primarily caused by the mismatch in dielectric constants of glass fiber and resin, leading to crosstalk and strength loss.
Innovation Solution
A laminated structure is introduced with resin isolation layers on both sides of the signal transmission layer, reducing the influence of glass fiber on signal quality, and reinforcing layers on opposite sides to compensate for strength loss, using a combination of glass fiber and resin to maintain structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass fiber and resin are used as dielectric layers in conventional PCBs, then structural strength is provided, but dielectric constant mismatch causes signal integrity issues including skew distortion and electromagnetic interference
Solution Approach 1:
The dielectric layer is segmented into multiple sub-layers: a first dielectric sub-layer adjacent to the signal transmission layer with lower dielectric constant, and a second dielectric sub-layer with higher dielectric constant. This segmentation allows each sub-layer to serve different functions - the first sub-layer minimizes electromagnetic interference while the second sub-layer provides structural strength, thereby resolving the contradiction between signal integrity and structural strength.
Solution Approach 2:
Different regions of the dielectric layer are assigned different material properties. The first dielectric sub-layer uses materials with lower dielectric constant (e.g., polybutylene terephthalate) near the signal transmission layer to reduce electromagnetic interference, while the second dielectric sub-layer uses materials with higher dielectric constant (e.g., glass fiber reinforced resin) to provide structural strength. This local differentiation of material properties resolves the contradiction between signal integrity and structural strength.
2Object-affected harmful factors
If resin isolation layers are added adjacent to the signal transmission layer, then electromagnetic interference is reduced, but mechanical strength may be compromised
Solution Approach 1:
The dielectric layer is divided into two functional segments: the first dielectric sub-layer (resin isolation layer) adjacent to the signal transmission layer provides electromagnetic interference protection, while the second dielectric sub-layer provides mechanical strength. This segmentation allows the system to achieve both reduced electromagnetic interference and maintained mechanical strength simultaneously.
Solution Approach 2:
The patent employs composite dielectric structures combining different materials with complementary properties. The first dielectric sub-layer uses low-dielectric-constant materials (such as polybutylene terephthalate) to minimize electromagnetic interference, while the second dielectric sub-layer uses high-dielectric-constant reinforcement materials (such as glass fiber reinforced resin) to provide mechanical strength. This composite approach resolves the contradiction between reducing electromagnetic interference and maintaining mechanical strength.
3Productivity
If high wiring density and high routing density are implemented for high-speed signal transmission, then signal transmission capability is improved, but signal integrity deteriorates due to increased electromagnetic interference and skew distortion
Solution Approach 1:
The patent changes the dielectric parameters of the layers adjacent to the signal transmission layer by introducing a first dielectric sub-layer with specifically controlled low dielectric constant and low loss tangent. This parameter change reduces electromagnetic interference and skew distortion, thereby maintaining signal integrity even as wiring density and routing density are increased for high-speed signal transmission.
Data Source
AI summary
According to embodiments of the present disclosure, a laminated unit for a printed circuit board and a printed circuit board are provided. The laminated unit includes a plurality of metal layers and a plurality of dielectric layers alternately stacked in a thickness direction, wherein the plurality of metal layers include a signal transmission layer and a pair of reference layers disposed on two sides of the signal transmission layer; at least one of two dielectric layers adjacent to the signal transmission layer is arranged as a resin isolation layer; and the dielectric layers on sides of the pair of reference layers opposite to the signal transmission layer are arranged as reinforcing layers, and the reinforcing layers include a substrate and a resin material arranged around the substrate.