Back to the Cleaning Basics
This year, we at the Cleaning Chronicles are looking forward to providing our thoughts on cleaning topics, trends, and advancements in the SMT electronics industry. But we thought we’d kick things off by getting back to the basics of why PCB Cleaning is so important and what some potential options are.
As PCB manufacturing advances through 2021 and beyond, we will see more and more miniaturized components, increased component densities and decreased stand-off heights. Complex environments continue to demand more and more reliability from technology. This reliability in turn demands the printed circuit board be free of impurities.
When components are soldered to a PCB, flux residues remain present on the board. Depending on the solder paste used, the amount and type that remains can vary. Even no-clean solder paste will still leave flux residues that can impact the performance and reliability of the assembly.
When considering PCB cleaning, you have options. Firstly, do nothing. Don’t clean. We might be biased, but we strongly advise against that. Believe it or not, there are several companies out there who don’t. Why would you clean? Not cleaning increases the risk of field failures, which leads to lost production time due to rework, damage to your company’s reputation in the marketplace, or increased costs related to recalls.
A second option is to use DI water. DI-water alone can only clean “water-soluble” residues and has limited to no ability to solubilize non-ionic residues on the board’s surface. DI-water’s high surface tension (70 dynes/cm) also limits its ability to clean under low-standoff components or between components on densely designed boards.
Then we have Isopropyl Alcohol (IPA). For many years IPA was the standard cleaning agent used in PCB cleaning applications. IPA is volatile and flammable which poses challenges and risks with its use. Those challenges and risks include high product loss due to evaporation, and fire/explosion risk due to its very low flash-point. If you live in a jurisdiction with VOC air-quality regulations, IPA may violate those environmental protection rules.
Finally, we come to engineered chemistry-based cleaning agents. Both Alkaline and pH-Neutral PCB cleaning options exist and are designed to mitigate the above-mentioned concerns with DI-water and IPA while improving cleaning performance.
For example, chemistry-assisted cleaning processes can reduce surface tensions to 30 dynes/cm and below, allowing the spaces under low-standoff components to be reached and cleaned. Today’s cutting-edge pH-neutral PCB cleaning agents clean of a wide variety of contaminants including newer synthetic resins. The pH-neutrality of these chemicals in combination with inhibition packages protect sensitive metals. And if safety is your concern, today’s cleaning chemistries can offer lower VOC levels and better safety ratings to protect users.
If you’re thinking about how to clean or even wondering if you should, perhaps it makes sense to reach out for a second opinion from an industry partner or a cleaning agent provider for recommendations!