Printed Wiring Board Adhesion via Sputtered Alloy Seed Layer
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Solution Overview
Problem
Existing printed wiring boards face issues with insufficient adhesion between conductor circuits and resin insulating layers, leading to potential peeling and signal propagation speed variations, which can cause noise and malfunction in electronic devices.
Innovation Solution
A printed wiring board design featuring a first conductor layer, a resin insulating layer with glass particles, a second conductor layer with a seed layer and electrolytic plating layer formed by sputtering an alloy containing copper, aluminum, and specific metals like nickel, zinc, gallium, or silicon, and a via conductor connecting the layers, ensuring strong adhesion and uniform signal propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional resin insulating layer is used without glass particles on the inner wall surface, then the manufacturing process is simpler, but the adhesion between conductor layers and insulating layer is insufficient causing peeling
Solution Approach 1:
The patent applies local quality by creating different surface compositions at different locations of the insulating layer. The inner wall surface of the opening contains glass particles for enhanced adhesion, while the outer surface maintains a resin-only composition for smooth signal propagation. This localized differentiation resolves the contradiction by providing enhanced adhesion only where needed (at the via conductor interface) without complicating the entire insulating layer structure.
2Strength
If the inner wall surface of the opening includes only resin, then the structure is simpler, but adhesion is insufficient leading to peeling under thermal stress
Solution Approach 1:
The patent employs composite materials by combining glass particles with resin in the inner wall surface of the opening. This composite structure provides superior adhesion properties compared to pure resin, enabling the via conductor to maintain strong bonding under thermal stress. The glass particles act as reinforcement agents that enhance the mechanical interlocking and chemical bonding between the conductor and insulating layer, resolving the adhesion issue without significantly complicating the manufacturing process.
3Strength
If the outer surface of the resin insulating layer includes glass particles, then adhesion is enhanced, but signal propagation speed varies causing noise
Solution Approach 1:
The patent applies local quality by spatially separating the functional requirements: glass particles are confined to the inner wall surface of the opening where adhesion is critical, while the outer surface remains free of glass particles to ensure uniform signal propagation. This localized placement resolves the contradiction by providing enhanced adhesion only at the via conductor interface without introducing signal propagation variations that would cause noise.
4Strength
If conventional seed layers are used without specific alloy composition, then manufacturing is easier, but adhesion between conductor layers and insulating layer is insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the seed layer's chemical composition to include specific alloying elements (such as palladium, nickel, or copper) in controlled proportions. This compositional adjustment enhances the adhesion between the conductor layers and the insulating layer by improving wetting properties and chemical bonding. The parameter change in alloy composition resolves the adhesion issue without significantly complicating the manufacturing process, as the modified seed layer can still be deposited using standard sputtering techniques.
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 design enhances adhesion strength and reduces signal propagation speed variations, suppressing noise and ensuring reliable data transmission even under thermal stress, resulting in a high-quality printed wiring board.
Implementation Method 1
the seed layer is formed by sputtering an alloy including copper, aluminum, and one or more metals selected from nickel, zinc, gallium, silicon, and magnesium
Data Source
AI summary
A printed wiring board includes a first conductor layer, a resin insulating layer including glass particles and resin, a second conductor layer formed on a surface of the resin insulating layer and including a seed layer and an electrolytic plating layer, and a via conductor connecting the first conductor layer and second conductor layer and including the seed layer and electrolytic plating layer extending from the second conductor layer. The second conductor layer and the via conductor are formed such that the second conductor layer includes signal wirings and that the seed layer is formed by sputtering an alloy including copper, aluminum, and one or more metals selected from nickel, zinc, gallium, silicon, and magnesium, and the resin insulating layer is formed such that the surface of the resin insulating layer includes the resin and that an inner wall surface in the opening includes the resin and the glass particles.