PCB Vapor-Phase Treatment for Uniform Protective Coating
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Solution Overview
Problem
Wave soldering reduces the surface energy of printed circuit boards, making it difficult for a transparent protective coating to evenly wet the surface, as the low surface energy prevents complete coverage.
Innovation Solution
Treating the printed circuit board in a vapor phase soldering system, using a heat transfer medium like perfluoropolyether with a boiling point below 160°C, increases the surface energy without melting the solder, specifically within a treatment duration of 4 to 12 minutes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wave soldering is used to solder components to the circuit board, then the components are reliably attached to the board, but the surface energy of the circuit board is reduced, preventing uniform coating of protective lacquer
Solution Approach 1:
The patent applies parameter changes by treating the circuit board with vapor phase soldering at controlled temperatures (below solder melting point) to modify the surface energy parameters of the board. This changes the surface properties to enable proper wetting by protective coatings while preserving the existing solder joints.
Solution Approach 2:
The patent uses preliminary action by performing vapor phase treatment before applying the protective coating. This pre-treatment modifies the surface energy of the circuit board in advance, ensuring that when the protective coating is applied afterward, it will uniformly wet and cover the entire surface including previously soldered areas.
2Ease of manufacture
If high temperature is applied to increase surface energy, then the surface energy increases, but the solder joints melt and compromise component connections
Solution Approach 1:
The patent applies parameter changes by precisely controlling the temperature parameter during vapor phase treatment to remain below the melting point of solder (typically maintaining temperatures between 100-150°C). This allows surface energy modification without reaching temperatures that would melt the solder joints.
Solution Approach 2:
The patent uses an intermediary approach by introducing vapor phase soldering as an intermediate treatment step between wave soldering and protective coating application. This intermediary process modifies surface energy through vapor exposure rather than direct liquid solder contact, enabling surface treatment without compromising existing solder joints.
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 method effectively enhances the surface energy of the printed circuit board, ensuring the protective coating uniformly covers the surface, thereby improving the soldering process and coating application.
Implementation Method 1
treating the circuit board in a vapor phase soldering system
Implementation Method 2
the heat transfer medium comprises perfluoropolyether
Implementation Method 3
The solder side of the circuit board is first coated with flux
Data Source
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AI summary
The invention relates to a method for increasing a surface energy of a printed circuit board equipped with components that are soldered using a wave soldering process, said method involving the step of treating the printed circuit board in a vapor-phase soldering system by means of a heat transfer medium.