Nitride Seed Layer PCB Adhesion and Thermal Shock
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Solution Overview
Problem
Conventional semi-additive methods for forming printed circuit board (PCB) circuit patterns require a thick seed layer for uniformity, leading to long lead times and difficulties in creating fine pitches, as well as inadequate adhesion between the metal layer and insulating resin.
Innovation Solution
A PCB structure featuring a first seed layer of nitride materials (such as TiN, NiN, CuN, MoN, TaN, or CrN) with a thickness of 10-70 nm, and a second seed layer of copper or nickel with a thickness of 200-400 nm, which enhances adhesion without the need for separate surface roughness treatment, and minimizes thermal shock differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a thick seed layer (10000 Å or more) is used to ensure uniform coverage on the entire substrate, then the uniformity of the seed layer is improved, but the lead time of the flesh etching process becomes long and it becomes difficult to form fine pitches
Solution Approach 1:
The patent divides the single thick seed layer into two separate seed layers: a first seed layer (100-500 Å) formed directly on the substrate, and a second seed layer (500-1000 Å) formed on top of the first seed layer. This segmentation allows the etching process to remove only the thinner second seed layer more quickly, reducing lead time while maintaining uniform coverage through the combined thickness of both layers.
Solution Approach 2:
The patent applies different thicknesses to different portions of the seed layer structure. The first seed layer has a thickness of 100-500 Å providing base uniformity, while the second seed layer has a thickness of 500-1000 Å providing additional uniformity and etch selectivity. This local differentiation in thickness optimizes both uniformity and etching efficiency.
2Stability of the object's composition
If a thick seed layer is used to ensure uniform coverage, then the uniformity of the seed layer is improved, but it becomes difficult to form fine pitches
Solution Approach 1:
By segmenting the seed layer into two distinct layers with different thicknesses and properties, the patent enables better control over the etching process. The thinner first seed layer (100-500 Å) allows for more precise etching to achieve fine pitches, while the overall combined structure maintains uniform coverage.
Solution Approach 2:
The patent changes the thickness parameter of the seed layer from a single thick layer (10000 Å or more) to a layered structure with controlled thicknesses (first layer: 100-500 Å, second layer: 500-1000 Å). This parameter optimization enables fine pitch formation while maintaining uniformity.
3Ease of manufacture
If conventional seed layers are used, then the circuit pattern can be formed, but the bonding force between the substrate and metal layer is insufficient
Solution Approach 1:
The patent uses a composite seed layer structure combining two different materials with distinct properties. The first seed layer uses material A (e.g., tungsten, molybdenum, or titanium) providing strong substrate adhesion, while the second seed layer uses material B (e.g., copper, nickel, or palladium) providing excellent electrical conductivity and metal layer bonding. This composite structure maximizes both manufacturing ease and bonding strength.
Solution Approach 2:
The first seed layer acts as an intermediary between the substrate and the second seed layer. It provides a transition interface that enhances bonding strength, allowing the metal layer to adhere more effectively to the substrate through the mediating first seed layer.
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 proposed solution maximizes adhesion between the circuit pattern and insulating resin, enabling the formation of fine patterns without additional surface treatment and reducing thermal shock deviations by using nitride and metal seed layers.
Implementation Method 1
improving a bonding force between a substrate and a metal layer by forming a circuit pattern on a metal layer including a nitride as a seed layer
Implementation Method 2
forming a metal layer on a surface of the second seed layer exposed through the opening by electroplating
Data Source
AI summary
A printed circuit board (PCB) includes: a substrate; and a circuit pattern disposed on the substrate, wherein the circuit pattern includes a first seed layer disposed on the substrate and including a nitride, and a metal layer disposed on the first seed layer.