Wiring Substrate with Buried Metal Core Plate
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Solution Overview
Problem
The challenge is to create a wiring substrate that reduces warpage while maintaining mechanical strength and enables high-speed signal transmission, as existing substrates with reduced thickness suffer from stiffness loss and high-density wiring patterns experience crosstalk and noise.
Innovation Solution
A wiring substrate design featuring a metal core plate with a low coefficient of thermal expansion and high Young's modulus, buried in an insulating layer with a coaxial structure of signal and ground lines, and via wiring to reduce warpage and noise, while maintaining mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of the core substrate is reduced to meet the demand for smaller size, then the size of the wiring substrate is reduced, but the mechanical strength and stiffness of the core substrate deteriorates causing warpage
Solution Approach 1:
The patent uses a composite structure combining a metal core plate (providing mechanical strength and stiffness) with an insulating layer (providing electrical insulation and allowing thin profile). This composite approach enables the substrate to maintain mechanical integrity while achieving reduced thickness, directly resolving the contradiction between size reduction and strength maintenance.
Solution Approach 2:
The metal core plate is strategically positioned at the center of the insulating layer in the thickness direction, providing localized reinforcement exactly where mechanical strength is most needed to prevent warpage. This localized quality enhancement allows the overall substrate to be thin while maintaining stiffness at critical points.
2Quantity of substance
If high-density wiring patterns are used to increase component density, then the wiring density is increased, but crosstalk and noise between wiring patterns increases affecting high-speed signal transmission
Solution Approach 1:
The patent extracts and positions a ground line concentrically around the signal line, creating a dedicated shielding structure that isolates the signal from external electromagnetic interference and crosstalk. This extracted ground element acts as a protective barrier, enabling high-density wiring while maintaining signal integrity.
Solution Approach 2:
The ground line serves as an intermediary element between the signal line and surrounding wiring patterns. It mediates the electromagnetic field interactions, blocking crosstalk from adjacent wires while allowing the high-density wiring configuration to proceed. The ground line acts as a protective intermediary that enables closer wiring spacing without sacrificing signal quality.
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
The solution effectively reduces warpage and enhances high-speed signal transmission by maintaining stiffness and controlling noise and crosstalk, improving electrical characteristics and impedance.
Implementation Method 1
a metal core plate with a low coefficient of thermal expansion
Implementation Method 2
a via wiring buried in the insulating layer to have a first end face exposed at the first surface and joined to the lowermost one of the wiring layers, and a second end face joined to the metal core plate
Data Source
AI summary
A wiring substrate includes an insulating layer, a stack including wiring layers and photosensitive-resin insulating layers on a first surface of the insulating layer, a wiring layer on a second surface of the insulating layer, having a lower wiring density than the wiring layers, a metal core plate buried in the insulating layer and positioned on the stack side with respect to the center of the insulating layer in its thickness direction, and a via wiring buried in the insulating layer to have a first end face exposed at the first surface and joined to the lowermost one of the wiring layers, and a second end face joined to the metal core plate. The first surface and the first end face are substantially flush with each other. The wiring layers include a signal line, and a ground line concentrically formed around the signal line, with a predetermined interval therebetween.