Water-Based Pore Sealing Agent for PCB Plating Layer Corrosion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing technologies for preventing oxidation and corrosion of printed circuit board (PCB) plating layers, particularly nickel and gold layers, are inadequate due to surface defects and residues in micropores, leading to assembly defects, increased contact resistance, and electrochemical corrosion, which conventional methods like thickening the gold layer and vacuum packaging cannot fully address.
Innovation Solution
A water-based pore sealing agent is developed, comprising corrosion inhibitors, surfactants, ion chelating agents, and pH regulators, which immerses the PCB plating layer to remove residues and defects, creating a protective film that prevents corrosion by lowering surface tension to allow deep penetration and effective cleaning of micropores.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gold-plating layer is thickened to prevent oxidation and corrosion, then the anti-oxidation and anti-corrosion properties are improved, but the manufacturing cost increases and the difficulty of manufacture increases
Solution Approach 1:
The patent introduces a pore sealing agent as an intermediary substance that fills micropores and defects in the plating layer. This agent acts as a mediator between the plating layer and the corrosive environment, preventing corrosion without requiring increased gold layer thickness, thereby resolving the contradiction between reliability and manufacturing cost
Solution Approach 2:
The patent changes the surface tension parameter of the sealing solution by using surfactants, enabling the solution to penetrate and fill micropores effectively. This parameter change allows the sealing agent to address corrosion issues without increasing material thickness, thus improving reliability while maintaining manufacturing efficiency
2Reliability
If vacuum packaging is applied to prevent corrosion, then the oxidation from air is reduced, but it cannot prevent corrosion from remained air and does not work for assembled PCB exposed to air
Solution Approach 1:
The patent applies preliminary anti-action by filling micropores and defects with a pore sealing agent before the corrosion process begins. This preventive measure creates a barrier that stops corrosion at its source, providing long-term protection that works for both unassembled and assembled PCBs exposed to air, unlike vacuum packaging which only works for unassembled boards
3Ease of manufacture
If conventional water washing is used to clean PCB, then the cleaning process is simple, but residues in micropores cannot be totally removed leading to electrochemical corrosion
Solution Approach 1:
The patent changes the surface tension parameter of the cleaning solution by adding surfactants, transforming conventional water into a low-surface-tension solution that can penetrate and remove residues from micropores. This parameter change enables effective residue removal while maintaining a simple immersion cleaning process, resolving the contradiction between process simplicity and cleaning effectiveness
Solution Approach 2:
The patent uses a chemical solution that replicates the penetrating ability of more complex cleaning methods. The pore sealing agent solution copies the effectiveness of thorough mechanical cleaning while being simpler to apply, allowing complete residue removal through chemical action rather than mechanical means
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 water-based pore sealing agent significantly enhances the anti-oxidation and anti-corrosion properties of PCB plating layers, reducing the risk of corrosion and assembly failures, as demonstrated by improved performance in neutral salt spray, nitric acid vapor, mixed gas, and bonding tensile strength tests, with a substantial increase in product qualification rates and long-term reliability.
Implementation Method 1
creating a protective film that prevents corrosion by lowering surface tension to allow deep penetration and effective cleaning of micropores
Implementation Method 2
a high-density self-passivating film is easy to be formed on the surface of the nickel layer
Implementation Method 3
ion chelating agents, and pH regulators, which immerses the PCB plating layer to remove residues and defects
Data Source
AI summary
The present invention relates to a water-based pore sealing agent enhancing PCB coating anti-oxidation and anti-corrosion properties, consisting of, by weight, 4-12 parts of a corrosion inhibitor, 15-25 parts of a mixed surfactants system, 10-20 parts of an ion chelating agent, 6-15 parts of a pH regulator, 20-40 parts of a builder, and the rest being purified water. When used to perform pore sealing on a PCB, the water-based pore sealing agent is diluted with purified water first to be diluted 10-100 times, preferably, 100/8-100/3 times. The pH value is 7-11, and is preferably 7.5-9.5. The surface tension is 18-28 dyn/cm. The pore sealing treatment uses a immersion process, and preferably ultrasonic waves are added at the same time to assist in cleaning the pores. For the pore sealing treatment, the temperature is 20-60° C., and the time is 60-150 seconds. After pore sealing, the temperature for drying the coated piece is 80-150° C., and the time is 60-120 seconds. The PCB treated with the water-based pore sealing agent of the present invention undergoes the neutral salt spray test, the nitric acid vapor test, the mixed gas test, and the sulfur dioxide and bonding tensile strength test, and the results have indicated that the anti-oxidation and anti-corrosion properties of the coating thereof are significantly enhanced.