scholarly journals Removing Acrylic Conformal Coating with Safer Solvents for Re-Manufacturing Electronics

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 937
Author(s):  
Taofeng Lu ◽  
Gregory Reimonn ◽  
Gregory Morose ◽  
Evan Yu ◽  
Wan-Ting Chen
Keyword(s):  
Printed Circuit Boards ◽  
Methylene Chloride ◽  
Human Health Risk ◽  
Solubility Parameters ◽  
Circuit Boards ◽  
Hansen Solubility Parameters ◽  
Conformal Coating ◽  
Data Processing Method ◽  
Conformal Coatings ◽  
Solvent Blends

Conformal coating is typically composed of polymeric film and is used to protect delicate electronic components such as printed-circuit boards. Without removing conformal coating, it would be difficult to repair these complicated electronics. Methylene chloride, also called dichloromethane (DCM), has a widespread usage in conformal coating stripper products. The high toxicity of DCM increases human health risk when workers are exposed to DCM during the conformal coating removal processes. Therefore, the replacement of DCM would be beneficial to greatly improve the overall safety profile for workers in the electronics and coating industries. This research identified and evaluated alternative chemicals for replacing DCM used in acrylic conformal coating stripping operations. The solubility of an acrylic conformal coating was measured and characterized using Hansen solubility parameters (HSP) theory. Coating dwell time tests using various solvent blends verified the accuracy of the created HSP solubility sphere. A data processing method was also developed to identify and screen potential alternative solvent blends in terms of safety, toxicity, and cost-effectiveness. The identified safer solvent blends were demonstrated to provide equivalent stripping performance as compared to DCM based coating strippers within an acceptable cost range. The results of this research will be of value to other types of conformal coatings, such as silicone and polyurethane, where DCM is commonly used in similar coating stripping operations. By safely removing conformal coating, delicate electronics would be available for re-manufacturing, enabling a circular economy.

Degradation of conformal coatings on printed circuit boards due to partial discharge

2016 ◽  
Vol 23 (4) ◽  
pp. 2232-2240 ◽  
Author(s):  
Christopher Emersic ◽  
Robert Lowndes ◽  
Ian Cotton ◽  
Simon Rowland ◽  
Robert Freer
Keyword(s):  
Printed Circuit Boards ◽  
Partial Discharge ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Conformal Coatings

Arcing and Spacing Requirements for High Voltage Printed Circuit Boards

2015 ◽  
Author(s):  
Prabjit Singh
Keyword(s):  
High Voltage ◽  
Printed Circuit Boards ◽  
Power Supplies ◽  
Circuit Boards ◽  
High Voltage Power Supply ◽  
Conformal Coating ◽  
Printed Circuit ◽  
Electronic Hardware ◽  
Vacuum Test ◽  
Partial Vacuum

The electronic hardware miniaturization trend continues unabated. The reduced feature spacing expose the high voltage power supply circuits to arcing. The power MOSFET gate to drain and the drain to source lead gaps are narrow enough for zinc whiskers emanating from under the raised floor zinc plated tiles to arc across the MOSFET leads. Arcing can also occur because of paper cellulose fibers and dust in high relative humidity environments. The physics of arcing will be presented. Paschen’s law of arcing will be described; it will be shown how the law led to a novel way of testing power supplies for propensity to arcing. Examples of application of the test, called the partial vacuum test, to power supplies will be described. Testing the integrity of conformal coating is one useful application of the partial vacuum test. A novel zinc whisker spray test, developed to determine the spacing required to avoid arcing between features at high electric potential between them, will be described and its results will be presented that verify the UL feature spacing guidelines.

scholarly journals Using Solubility Parameters to Model More Environmentally Friendly Solvent Blends for Organic Solar Cell Active Layers

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3889
Author(s):  
Ishita Jalan ◽  
Lisa Lundin ◽  
Jan van Stam
Keyword(s):  
Organic Solar Cells ◽  
Industrial Applications ◽  
Solution Chemistry ◽  
Solubility Parameters ◽  
Hansen Solubility Parameters ◽  
Acceptor Pair ◽  
Active Layers ◽  
Donor Acceptor ◽  
Solvent Blends ◽  
Hansen Solubility

To facilitate industrial applications, as well as for environmental and health purposes, there is a need to find less hazardous solvents for processing the photoactive layer of organic solar cells. As there are vast amounts of possibilities to combine organic solvents and solutes, it is of high importance to find paths to discriminate among the solution chemistry possibilities on a theoretical basis. Using Hansen solubility parameters (HSP) offers such a path. We report on some examples of solvent blends that have been found by modelling HSP for an electron donor polymer (TQ1) and an electron acceptor polymer (N2200) to match solvent blends of less hazardous solvents than those commonly used. After the theoretical screening procedure, solubility tests were performed to determine the HSP parameters relevant for the TQ1:N2200 pair in the calculated solvent blends. Finally, thin solid films were prepared by spin-coating from the solvent blends that turned out to be good solvents to the donor-acceptor pair. Our results show that the blend film morphology prepared in this way is similar to those obtained from chloroform solutions.

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