Duo-Solvent Cleaning for Removing Flux Residue from Class 3 Hardware
The research study evaluates the cleaning and electrical performance using the IPC B-52 Test Vehicle.
Production Floor
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Authored By:
Mike Bixenman
Kyzen Corporation
Nashville, TN
Summary
Packaging trends enable disruptive technologies. The miniaturization of components reduces the distance between conductive paths. Cleanliness of electronic hardware based on the service exposure of electrical equipment and controls can improve the reliability and cost effectiveness of the entire system. Problems resulting from leakage currents and electrochemical migration lead to unintended power disruption and intermittent performance problems due to corrosion issues.
Solvent cleaning has a long history of use for cleaning electronic hardware. Limitations with solvent based cleaning agents due to environmental effects and the ability to clean new flux designs commonly used to join miniaturized components has limited the use of solvent cleaning processes for cleaning electronic hardware. To address these limitations, new solvent cleaning agents and processes have been designed to clean highly dense electronic hardware.
The research study will evaluate the cleaning and electrical performance using the IPC B-52 Test Vehicle. Lead Free no-clean solder paste will be used to join the components to the test vehicle. Ion Chromatography and SIR values will be reported.
Conclusions
The Duo-Solvent cleaning process is designed to remove flux from Printed Circuit boards using an engineered solvating cleaning composition. Following the cleaning process, the PCB is rinsed in a solvent to remove excess solvating agent and ionic residues. The process produces clean and dry PCBs in one machine with short cycle time, low energy usage and small footprint.
Flux compositions are multi compositional soils. Cleaning fluids designed for Duo-Solvent process require a combination of dispersive, polar and hydrogen bonding forces. Engineered cleaning fluids require the ability to clean multi-compositional flux residues and rinse with a high vapor pressure solvent composition. The high vapor pressure rinse solvent enables a waterless solvent-based process for cleaning printed circuit assemblies. The data found that the process is effective at removing no-clean Lead-free flux residues. The rinse fluid is effective at removing drag-out from wash process and ionic residues during the rinse process.
Properly designed cleaning equipment enables the process. The solvating agent is processed in a cleaning module external to the vapor degreaser. The rinse solvent requires a low surface tension and solubility with the cleaning solvent. The first rinse takes place in the boil sump with the rinse sump and vapor zones providing final rinses. A solvent separation system cleans and recovers the rinse solvent on a continuous basis. The process design provides a waterless cleaning design.
Initially Published in the IPC Proceedings
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