Multilayer Wiring Board Structure for Smoother Conductor Interfaces
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Solution Overview
Problem
Existing wiring boards with glass-ceramics in dielectric layers experience rough interfaces with wiring conductors, leading to decreased conductivity and transmission loss due to the skin effect, especially at high frequencies, and are prone to structural defects like peeling.
Innovation Solution
A wiring board design with a first dielectric layer containing a first glass and ceramic filler, and a second dielectric layer interposed between the wiring conductor and the first dielectric layer, where the second glass has a higher sintering temperature and smaller grain size than the first, reducing interface roughness and maintaining the grain shape during sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass-ceramics are used for the dielectric layer, then strength and heat resistance are improved, but interface roughness increases due to crystal precipitation
Solution Approach 1:
The dielectric layer is divided into two distinct layers: a first dielectric layer containing glass-ceramics for strength and heat resistance, and a second dielectric layer with non-crystallized glass for smooth interface. This segmentation allows each layer to fulfill its specific function without compromise.
Solution Approach 2:
The second dielectric layer acts as an intermediary between the wiring conductor and the first dielectric layer. It provides a smooth interface that reduces roughness while the first dielectric layer maintains the overall structural strength and heat resistance.
2Manufacturing precision
If an intermediate layer of non-crystallized glass is added, then interface roughness is reduced, but device complexity increases
Solution Approach 1:
The patent controls interface roughness by changing material parameters - specifically using non-crystallized glass with smaller grain size for the second dielectric layer. This parameter-based approach reduces interface roughness without requiring complex structural modifications.
3Reliability
If interface roughness is reduced, then conductivity is improved, but sintering temperature control becomes more difficult
Solution Approach 1:
Different regions of the dielectric structure use materials with different sintering characteristics. The second dielectric layer near the conductor uses material with lower sintering temperature for smooth interface formation, while the first dielectric layer uses glass-ceramics with higher sintering temperature for strength.
Solution Approach 2:
The sintering process is designed to first form the second dielectric layer with smooth interface characteristics, then subsequently form the first dielectric layer with strength characteristics. This preliminary action ensures conductivity is optimized before adding structural reinforcement.
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
Reduces interface roughness and transmission loss, prevents structural defects like peeling, and maintains strength and heat resistance by controlling grain size and sintering temperatures in the dielectric layers.
Implementation Method 1
a sintering temperature of the second glass contained in the second dielectric layer is higher than a sintering temperature of the wiring conductor
Implementation Method 2
Glass-ceramics contain a crystallized glass and a ceramic filler
Implementation Method 3
When an electric signal passing through the wiring conductor has a high frequency, the electric signal passing through the wiring conductor concentrates near the interface with the dielectric layer because of a skin effect
Data Source
AI summary
A wiring board that includes: a wiring conductor; a first dielectric layer around the wiring conductor and containing a first glass and a first ceramic filler; and a second dielectric layer interposed between the wiring conductor and the first dielectric layer, the second dielectric layer being in contact with the wiring conductor and the first dielectric layer, and the second dielectric layer containing a second glass and a second ceramic filler. A sintering temperature of the second glass contained in the second dielectric layer is higher than a sintering temperature of the wiring conductor, and a grain size of the second glass contained in the second dielectric layer is smaller than a grain size of the first glass contained in the first dielectric layer.