Composite Substrate Layout for Stable Impedance and Lower Signal Loss
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Solution Overview
Problem
Conventional PCBs with glass fiber bases have unstable dielectric constants, leading to unstable impedance in transmission lines, warping, copper wire breaks, increased roughness, and high manufacturing costs due to chip packaging, which enlarges the signal transmission path and increases loss.
Innovation Solution
A composite substrate with a redistribution layer and a connecting layer, replacing the glass fiber base, utilizing a stable dielectric material like epoxy resin or silicone, and reducing the need for blackening and browning processes, thereby shortening signal transmission paths and reducing transmission loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PCB with glass fiber base is used, then structural support is provided, but dielectric constant instability causes impedance instability and transmission loss
Solution Approach 1:
The patent changes the dielectric material parameters by replacing glass fiber base with epoxy resin or silicone-based materials that have stable dielectric constants. This material substitution directly addresses the impedance stability issue by ensuring consistent dielectric properties throughout the substrate.
Solution Approach 2:
The invention uses composite material structures with multiple layers including epoxy resin layers, silicone rubber layers, and copper foil layers. These composite materials provide both structural support and stable dielectric properties, resolving the contradiction between mechanical strength and electrical stability.
2Strength
If blackening and browning processes are applied to copper wires, then adhesion between layers is increased, but copper wire breaks and surface roughness increases
Solution Approach 1:
The patent removes the blackening and browning processes from the manufacturing flow. By eliminating these harsh chemical treatments, the invention prevents copper wire breaks and maintains smooth surfaces while still achieving adequate adhesion through alternative methods.
3Reliability
If chip packaging is performed, then die is protected, but manufacturing cost increases and signal transmission path lengthens
Solution Approach 1:
The invention merges the die mounting process with the substrate manufacturing process by directly bonding dies to the epoxy resin or silicone rubber substrate during substrate fabrication. This integration eliminates separate packaging steps, reducing cost and transmission path length while maintaining die protection.
4Productivity
If conventional PCB manufacturing process is used, then mass production is enabled, but transmission loss increases due to rough copper surfaces
Solution Approach 1:
The patent changes the surface roughness parameter of copper conductors by eliminating blackening and browning processes. The smooth copper surfaces reduce signal transmission loss while the epoxy resin or silicone rubber substrate maintains manufacturability for mass production applications.
Data Source
AI summary
A communication device includes a plurality of dies, a composite substrate and at least one antenna. The composite substrate includes a PCB, a redistribution layer and a connecting layer. The connecting layer is configured to electrically connect the redistribution layer and the PCB. Each die is electrically connected to the redistribution layer. The distribution layer corresponding to each die is formed integrally. The PCB is disposed between the antenna and the redistribution layer. The antenna is electrically connected to the dies through the composite substrate. A manufacturing method of the composite substrate is also provided.