Wiring Substrate Seed Layer Alloy for Glass Adhesion
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Solution Overview
Problem
Current multilayer substrates face challenges in achieving high-quality, reliable connections between through-hole conductors and via conductors, particularly on glass substrates, due to issues with adhesion and thermal stability, which can lead to peeling and malfunction under heat cycles.
Innovation Solution
A wiring substrate design featuring a glass core substrate with through-hole conductors and via conductors formed using a seed layer and electrolytic plating layer, where the seed layer is made of an alloy containing copper, aluminum, and specific metals like nickel, zinc, gallium, or silicon, ensuring strong adhesion and thermal stability through sputtering and electroless plating processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductor layers are formed on glass substrates, then through-hole conductors can be created, but adhesion and thermal stability are insufficient leading to peeling under heat cycles
Solution Approach 1:
The patent uses a composite seed layer comprising multiple materials (e.g., Cu-Al alloy, Ni, Pd, Pt) to achieve both strong adhesion to the glass substrate and good electrical conductivity. This multi-material composite structure resolves the contradiction by combining materials with complementary properties: Cu-Al provides adhesion and conductivity, while Ni, Pd, or Pt enhance thermal stability and adhesion strength.
Solution Approach 2:
The patent optimizes the composition parameters of the seed layer, specifically controlling the Al content at 3-15 mass% and Cu content at 80-97 mass%, to achieve the optimal balance between adhesion strength and thermal stability. This parameter optimization allows the conductor layer to withstand heat cycles without peeling while maintaining reliable electrical connections.
2Strength
If seed layer is formed by sputtering with copper and aluminum alloy, then adhesion improves, but thermal stability may be compromised
Solution Approach 1:
The patent creates a composite seed layer structure where Cu-Al alloy (5-20 nm thick) provides adhesion to the glass substrate, while an additional layer of Ni (10-50 nm), Pd (5-30 nm), or Pt (5-30 nm) is deposited on top to provide thermal stability. This composite structure allows each material to perform its optimal function: Cu-Al for adhesion and Ni/Pd/Pt for thermal stability.
Solution Approach 2:
The patent applies different materials at different locations within the seed layer structure: the Cu-Al alloy layer is positioned at the interface with the glass substrate where adhesion is critical, while the Ni/Pd/Pt layer is positioned at the upper portion where thermal stability and oxidation resistance are critical. This local differentiation of material properties resolves the contradiction between adhesion and thermal stability.
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 robust and reliable connection between through-hole and via conductors, enhancing thermal stability and preventing peeling, while maintaining the glass substrate's flatness and smoothness, thus improving the overall performance and reliability of the wiring substrate.
Implementation Method 1
the seed layer is formed by sputtering and includes an alloy including copper, aluminum, and one or more metals selected from nickel, zinc, gallium, silicon, and magnesium
Implementation Method 2
a conductor layer formed on a surface of the resin insulating layer and including a seed layer and an electrolytic plating layer formed on the seed layer
Data Source
AI summary
A wiring substrate includes a core substrate including a through-hole conductor, a resin insulating layer formed on the core substrate, a conductor layer formed on a surface of the resin insulating layer and including a seed layer and an electrolytic plating layer formed on the seed layer, and a via conductor formed in the resin insulating layer such that the via conductor is connected to the through-hole conductor in the core substrate and includes the seed layer and electrolytic plating layer extending from the conductor layer. The core substrate includes a glass substrate such that the through-hole conductor is formed in a through hole penetrating through the glass substrate, and the conductor layer and via conductor are formed such that the seed layer is formed by sputtering and includes an alloy including copper, aluminum, and one or more metals selected from nickel, zinc, gallium, silicon, and magnesium.