PCB Metal Post Etching via Segmented Barrier Layers
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Solution Overview
Problem
The challenge lies in manufacturing printed circuit boards that are lighter, thinner, and smaller while maintaining the functionality of embedding electronic components, as existing methods face difficulties in achieving the required miniaturization and structural integrity without compromising the circuit's performance.
Innovation Solution
The solution involves a printed circuit board design with a multilayer structure, including an insulating layer, a circuit layer, and a solder resist layer with metal posts formed by patterning layers of different metals, where the post barrier layer and circuit barrier layer are reactive to specific etchants, allowing for precise etching and exposure of circuit elements, and a solder resist layer with a through-hole cavity to expose the circuit layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layered metal post structure is used, then the manufacturing process is simple, but the thickness uniformity and reactivity control during etching deteriorates
Solution Approach 1:
The metal post is divided into multiple layers (first post metal layer, second post metal layer) with a barrier layer in between. This segmentation allows each layer to be etched independently with different etchants, enabling precise control over the thickness and reactivity of each layer, thus resolving the contradiction between manufacturing simplicity and thickness uniformity.
Solution Approach 2:
Different materials are used for different layers of the metal post. The first post metal layer uses a material with specific reactivity to the first etchant, while the second post metal layer uses a material with specific reactivity to the second etchant. This local quality differentiation enables selective etching and precise thickness control for each layer.
2Length of stationary object
If the circuit layer thickness is reduced for thinner PCB design, then the overall board thickness decreases, but the structural integrity and electrical performance deteriorate
Solution Approach 1:
The circuit layer is constructed as a composite structure with a circuit metal layer and a circuit barrier layer. The circuit metal layer provides electrical conductivity while the circuit barrier layer provides structural support and prevents oxidation. This composite structure enables the circuit layer to maintain sufficient strength and electrical performance even when the overall thickness is reduced.
3Ease of manufacture
If a carrier board is used during manufacturing, then the manufacturing process is simplified, but the final product weight and size increase
Solution Approach 1:
The carrier board is used temporarily during the manufacturing process to provide support and enable precise fabrication of the metal post and circuit layer. After the manufacturing process is complete, the carrier board is removed, leaving only the final PCB product without the additional weight and size of the carrier board.
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
This approach enables the creation of printed circuit boards with reduced metal post thickness variability, improved structural integrity, and enhanced exposure of circuit elements, facilitating the integration of smaller electronic components while maintaining reliability and functionality.
Implementation Method 1
the post barrier layer has different reactivity to etchants, allowing for precise etching and forming metal posts with consistent thickness through a multi-step etching process
Data Source
AI summary
A printed circuit board and a method of manufacturing a printed circuit board are provided. The printed circuit board includes an insulating layer, a circuit layer embedded in the insulating layer, a solder resist layer disposed on one surface of the insulating layer, the solder resist layer having a cavity of a through-hole shape to expose a part of the circuit layer from the insulating layer, and a metal post embedded in the solder resist layer and exposed to outside via an opening of the solder resist layer, and the metal post includes a first post metal layer, a post barrier layer, and a second post metal layer disposed in that order.