Circuit Board Wire Structure Adhesion Promoter Layer
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Solution Overview
Problem
Conventional circuit board manufacturing methods result in non-homogeneous circuit layers with significant height differences and increased etching times, leading to reduced bonding strength and circuit density due to residual glue and uneven copper thickness.
Innovation Solution
A two-stage process for forming circuit layers using chemical copper electroplating to fill openings, with an adhesion promoter layer enhancing bonding strength and achieving precise control over circuit height and spacing, resulting in improved homogeneity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the surface circuit is formed on the surface of the multi-layer circuit board in the initial step with a thickness of approximately 3 μm, then the circuit layer can be formed, but the etching process requires more etching time and the lateral etching length increases to approximately 7 μm, reducing manufacturing precision
Solution Approach 1:
The patent segments the circuit layer formation into two distinct stages: first forming an initial circuit layer with chemical copper electroplating, then forming a final circuit layer with electroplating. This segmentation allows each stage to be optimized independently, with the initial layer providing a thin, uniform base that reduces the etching burden in subsequent steps.
Solution Approach 2:
The patent performs preliminary action by forming the initial circuit layer with controlled thickness before the final circuit layer. This preliminary layer serves as a foundation that reduces the amount of material requiring etching, thereby reducing lateral etching length and improving manufacturing precision.
2Manufacturing precision
If chemical solution electroplating is used to form the circuit layer on the surface of the multi-layer circuit board, then copper can be deposited, but the height of the circuit layer cannot be effectively controlled, resulting in a height difference of more than 2 μm, reducing manufacturing precision
Solution Approach 1:
The patent segments the electroplating process into two stages: chemical copper electroplating for the initial layer and conventional electroplating for the final layer. Each stage uses plating parameters optimized for its specific requirements, allowing precise control of height and thickness that cannot be achieved with a single electroplating process.
Solution Approach 2:
The patent changes key parameters between the two electroplating stages: using chemical copper electroplating with controlled deposition rates for uniform initial layer formation, then switching to conventional electroplating with adjusted current density and plating time for the final layer. These parameter changes enable precise height control within 2 μm tolerance.
3Reliability
If the circuit layer is formed by chemical solution electroplating, then copper can be deposited in openings, but the bonding strength between the circuit layer, surface circuit, and inner circuit is reduced due to residual glue and uneven surface, reducing reliability
Solution Approach 1:
The patent performs preliminary cleaning and surface preparation actions before circuit layer deposition, removing residual glue and smoothing the opening surfaces. This preliminary preparation ensures optimal bonding conditions for the chemical copper electroplating process, maximizing bonding strength between layers.
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 method achieves a height difference of less than 2 μm and circuit spacing of less than 3.5 μm, increasing circuit board density and reliability, and enabling application in 5G products with enhanced transmission rates.
Implementation Method 1
forming a first circuit layer in the at least one opening; forming a second circuit layer on the first circuit layer in the at least one opening and on the surface of the multi-layer circuit board
Implementation Method 2
an adhesion promoter layer enhancing bonding strength
Data Source
AI summary
A circuit board, comprising a multi-layer circuit board, a first conductive circuit, a first circuit layer, an adhesion promoter layer, a second conductive circuit, and a second circuit layer. The multi-layer circuit board comprises an inner circuit and an opening. The opening exposes the inner circuit. The first conductive circuit is disposed in the opening and on the inner circuit. The first circuit layer is disposed on the first conductive circuit in the opening and lower than the depth of the opening. The adhesion promoter layer is disposed in the opening and on the surface of the multi-layer circuit board and connected to the first conductive circuit. The second conductive circuit is disposed on the adhesion promoter layer and on the first circuit layer in the opening. The second circuit layer is disposed on the second conductive circuit in the opening and on the second conductive circuit.