Printed Wiring Board Base Layer for Via Adhesion and Signal Stability
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Solution Overview
Problem
Existing printed wiring boards face challenges in maintaining high adhesion strength between conductor layers and insulating layers, particularly at the interface of via holes, which can lead to peeling and reduced electrical performance due to uneven surfaces and varying permittivity.
Innovation Solution
Incorporating a base layer containing 0.2-5.0 at% iron or chromium between the resin insulating layer and the seed layer, along with a smooth outer surface and controlled inner wall texture through laser processing and argon plasma treatment, to enhance adhesion and reduce permittivity variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional resin insulating layer is used directly without a base layer, then the manufacturing process is simpler, but the adhesion strength between the conductor layer and insulating layer is insufficient
Solution Approach 1:
A base layer containing iron or chromium (0.2-5.0 at%) is introduced as an intermediary between the resin insulating layer and the conductor layer. This base layer acts as a mediator that enhances adhesion strength at the interface, preventing peeling while maintaining manufacturing feasibility.
Solution Approach 2:
The base layer is formed as a composite material containing resin and metal elements (iron or chromium) in specific proportions. This composite structure combines the insulating properties of resin with the adhesion-enhancing properties of metal, achieving both strong bonding and electrical insulation.
2Strength
If the inner wall surface of the resin insulating layer is left as-is, then the manufacturing process is simpler, but the adhesion at via hole interfaces is weak leading to peeling
Solution Approach 1:
The base layer is formed in advance on the inner wall surface of the resin insulating layer before conductor deposition. This preliminary action prepares the surface with enhanced adhesion properties, ensuring strong interface bonding without requiring complex post-processing steps.
Solution Approach 2:
The base layer is applied selectively to the inner wall surface of the resin insulating layer, particularly at via hole interfaces where adhesion is critical. This localized treatment enhances interface strength without uniformly modifying the entire structure, maintaining manufacturing efficiency.
3Reliability
If the resin insulating layer has a rough uneven surface, then surface area for bonding is increased, but permittivity becomes uneven causing signal propagation delays
Solution Approach 1:
The base layer is applied selectively to specific regions of the resin insulating layer surface, particularly at via hole interfaces and conductor contact areas. This localized application maintains the smooth outer surface for consistent permittivity while providing enhanced bonding at critical interfaces through the textured base layer structure.
Solution Approach 2:
The base layer serves as an intermediary between the smooth resin insulating layer and the conductor, providing a textured bonding surface that enhances adhesion strength without exposing the roughness to the external environment, thereby maintaining electrical performance consistency.
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 provides a high-quality printed wiring board with improved adhesion between conductor and insulating layers, reducing signal propagation delays and peeling, while maintaining consistent electrical performance and durability under thermal stress.
Implementation Method 1
smooth outer surface and controlled inner wall texture through laser processing
Implementation Method 2
argon plasma treatment, to enhance adhesion
Data Source
AI summary
A printed wiring board includes a first conductor layer, a resin insulating layer formed on the first conductor layer, a second conductor layer formed on the resin insulating layer and including a seed layer and a metal layer on the seed layer, a via conductor formed in the resin insulating layer such that the via conductor is connecting the first conductor layer and the second conductor layer, and a base layer formed on the resin insulating layer and including resin and one of iron and chromium in a range of 0.2 at % to 5.0 at % with respect to the resin such that the base layer includes part formed between the resin insulating layer and the seed layer.