Two-Layer Thermosetting Resin Sheet for PCB Conductor Embedding
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Solution Overview
Problem
Existing methods face challenges in embedding conductors in insulating layers of printed wiring boards without compromising moldability, as prepregs with glass cloths limit resin fillability, leading to insufficient resin flow and potential deformation.
Innovation Solution
A thermosetting resin sheet comprising a prepreg layer with a base member and an uncured or semi-cured resin composition, and a resin sheet layer with a longer curing time than the prepreg layer, allowing the resin sheet to flow and embed conductors effectively while minimizing deformation and resin overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a prepreg with glass cloth is used to form the insulating layer, then the structural strength is improved, but the resin fillability deteriorates leading to insufficient resin flow
Solution Approach 1:
The insulating layer is divided into two distinct layers: a prepreg layer (first layer) containing glass cloth for structural strength, and a resin sheet layer (second layer) without glass cloth for improved resin flow and fillability. This segmentation allows each layer to perform its specific function optimally without compromising the other.
Solution Approach 2:
Different regions of the insulating layer have different compositions and properties. The prepreg layer provides structural reinforcement where needed, while the resin sheet layer provides better resin flow and embedding characteristics in the region closer to the conductor, creating local quality variations to address specific functional requirements.
2Ease of operation
If the resin sheet is made to flow easily to embed the conductor, then the conductor embedding is improved, but the moldability deteriorates due to resin overflow and deformation
Solution Approach 1:
The resin sheet layer is designed with specific physical and chemical parameters including controlled resin content (30-70 wt%), optimized viscosity, and adjusted curing characteristics. These parameter changes enable the resin to flow sufficiently for conductor embedding while maintaining moldability and preventing deformation.
Solution Approach 2:
The resin sheet layer is formulated as a composite material containing thermosetting resin, curing agent, and inorganic filler in optimized proportions. This composite structure provides the right balance of flowability for embedding and structural integrity for moldability, resolving the contradiction between ease of conductor embedding and reliability of moldability.
3Manufacturing precision
If the resin content is increased to improve fillability, then the resin flow is improved, but the resin overflow and deformation increase
Solution Approach 1:
The resin content in the resin sheet layer is precisely controlled within the range of 30-70 wt%, and the viscosity is optimized to achieve the desired balance. This parameter optimization ensures sufficient resin flow for filling gaps around thick conductors while preventing excessive overflow and deformation during the molding process.
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 enables easier conductor embedding with reduced moldability issues, ensuring uniform resin flow and improved reliability in high-temperature environments, even with thick conductors, and reduces the chances of unfilled gaps and deformation in the insulating layer.
Implementation Method 1
a curing time of the resin sheet layer (3) is longer than a curing time of the prepreg layer (2)
Implementation Method 2
making it easier, while an insulating layer where a conductor is to be embedded is being formed, to embed the conductor in the insulating layer
Data Source
AI summary
A thermosetting resin sheet includes a prepreg layer and a resin sheet layer stacked on the prepreg layer. The prepreg layer includes a base member and an uncured product or semi-cured product of a first thermosetting resin composition impregnated into the base member. The resin sheet layer is an uncured product or semi-cured product of a second thermosetting resin composition. A curing time of the resin sheet layer is longer than a curing time of the prepreg layer.