PCB Via Structure Using Adhesive Layers and Etching
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Solution Overview
Problem
Existing thin multi-layer circuit boards face issues with high electrical resistance in vias formed using conductive paste and economical problems due to the need for laser drilling through each insulating layer.
Innovation Solution
The formation of vias through an etching process instead of laser drilling, using a multi-layer structure with copper via layers and adhesive layers, and aerosol deposition of copper for improved connectivity and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If vias are formed using conductive paste, then the via formation process is simple, but electrical resistance increases and signal reliability degrades
Solution Approach 1:
The patent replaces the conductive paste filling method with a mechanical plating process. Through electroplating or electroless plating, copper is deposited directly into the via holes to form conductive via structures. This substitution eliminates the high electrical resistance inherent in conductive paste while maintaining process simplicity, as plating is a standard PCB manufacturing technique that directly forms low-resistance conductive paths.
Solution Approach 2:
The patent changes the material parameter of the via filling substance from conductive paste (high resistance) to plated copper (low resistance). By controlling plating thickness and density, the via achieves optimal electrical conductivity. This parameter change directly addresses the electrical resistance issue while the plating process remains compatible with existing PCB manufacturing workflows.
2Manufacturing precision
If laser drilling is used to form vias through each insulating layer, then via precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the via formation step from the laser drilling process and replaces it with mechanical drilling followed by plating. This removes the expensive laser processing step while retaining via formation capability. The mechanical drilling method is more cost-effective for through-holes, and the subsequent plating ensures proper conductivity and insulation.
Solution Approach 2:
The patent employs disposable mechanical drill bits instead of expensive laser systems. Mechanical drilling with replaceable drill bits significantly reduces equipment investment and operational costs compared to laser drilling, while achieving sufficient via precision through proper drill bit selection and process control.
3Strength
If adhesive layer is added between via layers, then adhesive property is improved, but via structure complexity increases
Solution Approach 1:
The patent introduces an adhesive layer as an intermediary substance between the copper via layers and insulating layers. This adhesive layer serves as a bonding mediator that chemically or mechanically bonds the copper plating to the insulating material, ensuring strong adhesion. The adhesive is applied in thin layers during the lamination process, adding minimal structural complexity while dramatically improving bond strength.
Solution Approach 2:
The via structure becomes a composite construction with multiple materials: insulating layer material, adhesive material, and copper plating. This composite structure leverages the advantages of each material - the insulator provides electrical isolation, the adhesive provides bonding, and the copper provides conductivity. The layered composite approach is standard in PCB manufacturing and does not significantly increase overall complexity.
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 enhances the adhesive property between copper and insulating layers, improves heat radiation, and reduces manufacturing costs while maintaining signal integrity.
Implementation Method 1
an adhesive layer between the first and second via layers
Implementation Method 2
bulk copper is used, so that the heat radiation property can be improved
Implementation Method 3
etching the bulk metallic layers to expose the first and second insulating layers
Data Source
Figure 1~6
Figure 7~13
Figure 14~17
AI summary
Disclosed are a printed circuit board and a method for manufacturing the same. The printed circuit board includes a first insulating layer, a second insulating layer on the first insulating layer, and at least one via formed through the first and second insulating layers and having a layer structure. The via includes a first via layer formed through the first insulating layer, a second via layer formed on the first via layer while passing through the second insulating layer, and an adhesive layer between the first and second via layers. The first via layer has a section different from a section of the second via layer.