Cleaning medical electronics 101: a primer

Author : Jay Tourigny | Senior Vice President | MicroCare

01 February 2019

Circuit Boards

As technology advances at pace, entire categories of solutions that didn’t previously exist are being created, transforming the way we communicate, do business & thrive as communities. Medical electronics is one such example.

This article was originally featured in the February 2019 issue of EPDT magazine [read the digital issue]. Sign up to receive your own copy.

As MedTech revolutionises healthcare as we know it, there are implications related to improved quality of care and efficiency, lower costs, improved experiences and treatment processes, and more. Technology in the medical field has and continues to impact our lives and wellbeing. However, as Jay Tourigny, senior vice president at electronics cleaning experts, MicroCare explains, with new solutions come new challenges: for MedTech equipment, one important consideration for manufacturers is how best to clean medical electronics safely and effectively.

Cleaning electronics is no trivial task to begin with, because of the risk involved and the sensitive nature of the components, materials and engineering that need to be carefully constructed and maintained in order to function properly and keep the user safe. But for medical electronics, the stakes are even higher.

Cleaning standards
Among the many reasons why proper cleaning of medical electronics is so important, two particular reasons are: 1) the implications cleaning has for the next steps in the manufacturing process (for instance, sterilisation); and 2) device performance. Take pacemakers, for example. Before shipping a brand-new pacemaker, manufacturers need to ensure that any particulate, such as adhesives, coatings, finger residue or other material, is completely removed. Anything left on the product that isn’t meant to be there will negatively affect application of coatings or sterilisation. With the wide variety of possible contaminants, and increasingly miniature components of various geometries, cleaning has and will continue to become more complex.

Beyond removing harmful substances, cleaning is vital for the utility and functionality of medical electronic devices. The computing power and functionality of modern medical devices is directly proportional to the processing power of the printed circuit boards (PCBs) within them.

Failing solder joints cause a large percentage of PCB failures, so cleaning is key to their success. More sophisticated cleaning enables engineers to specify stronger, more active fluxes, which results in better solder joints. Problems with ‘cold joints’, insufficient wetting, bridging, and shorts can also be avoided. Better cleaning directly translates to more effective PCBs, which means better medical electronics.

Electrocardiograph with Pacemaker

Medical electronics also face strict regulation guidelines when it comes to design, manufacturing, certification, and, of course, maintenance and cleaning. Where consumer electronics can be manufactured for ‘good enough’ functionality, medical electronics have no such room for error. Quality, predictability and safety are all priority concerns for the sake of patients and medical staff, and the hospital and product manufacturers who are liable. ISO 10993, issued by the International Organization for Standardization, evaluates devices within a risk management framework to ensure they are safe, assessing bioburden, pyrogens and sterility to ensure that no harmful material remains on the tools we depend on to provide care. 

Under these guidelines, manufacturers are responsible for undergoing thorough validation before introducing any change in their manufacturing process, including new cleaning methods. Validated processes must prove to be consistently effective and repeatable – indefinitely – until the manufacturer chooses to undergo validation again. This rigorous process is costly in time, resources and energy, and few manufacturers willingly change course once an existing process is validated. Validation stresses the importance for companies to get it right the first time – not only in regard to the most effective cleaning process, but also the one that will be the most scalable, cost-efficient and adaptable long-term, especially as new product designs and solutions are introduced into the market.

Today’s options
Manufacturers have choices when it comes to cleaning solutions – not only that stand up to regulations, but also that meet a number of other considerations such as environmental impact, cost, efficiency, maintenance, clean room compatibility and more. As research has been conducted and equipment solutions have evolved, manufacturers have changed their preference for various cleaning agents over the years. It’s important that decision makers understand what the options are today and how they can be best prepared for the future. 

Historically, vapour degreasing was the default cleaning process for most industries when complex electronic equipment was introduced. However, concerns increased about the cleaning solvents’ environmental impact, and, in the 1990s, aqueous cleaning was introduced and favoured as a ‘greener’ option. Aqueous cleaning was also accepted for its cheaper cost per volume of liquid, and, at the time it was introduced, it worked well with the PCBs of that era. Until recently, aqueous cleaning methods have been the primary option and choice used by many manufacturers in the industry.

However, innovative new cleaning solvents have come a long way from the chemistry of decades past, and with new environmentally-friendly properties, many manufacturers are revisiting and favouring the benefits that vapour degreasing with solvents can provide. For young engineers who may have never seen a vapour degreaser in their career, and are unfamiliar with the thermodynamics involved, the process can seem magical, especially in contrast to the large, wet and noisy aqueous cleaning systems they are familiar with.

Vapor Degreaser in Lab

Vapour degreasing: how it works
Vapour degreasers (which are used for much more than cleaning greases, despite their generic name) are a closed-loop system that require two components: a specially-designed cleaning machine, and specific low-temp boiling nonflammable solvent as the cleaning agent. They range in size, and inside, you will find two chambers: the boil sump and the rinse sump – each descriptive of their purpose. In the boil sump, the solvent is heated and the parts are immersed and cleaned in the fluid. Once cleaned, the parts are mechanically transferred to the rinse sump for final cleaning in a pure, uncontaminated fluid. The parts come out clean, dry, spot-free and immediately ready for the next step in the process.

This smooth operation has a number of advantages. For starters, vapour degreasers have a significantly smaller footprint than other options. In a clean room, space is money. To meet regulations of a validated process, clean rooms are strictly controlled spaces that regulate temperature, air quality and other safety measurements. The larger the square footage of these spaces, the more expensive they are to maintain. Additionally, solvents boil at lower temperatures than water, so it takes less electricity to get things in motion. Vapour degreasers are known to be simpler to operate, requiring less training than more complex systems and fewer human resources to manage. Much of the cleaning activity in a vapour degreaser is automatically initiated – requiring only the touch of a button – in contrast to other cleaning methods that require more manual involvement or monitoring.

The solvent advantage
As it relates to performance, solvents are 20 to 40 percent heavier than water, which can aid in dislodging particulate more easily from components. Conversely, they have lower surface tension and lower viscosity than water, so they can more easily clean in small cracks and crevices, and quickly weep out rather than staying trapped. This becomes critical for several reasons. After cleaning, many products go into a coating stage. If any liquid remains on a piece of equipment, conformal coatings won’t adhere as they should. Additionally, any trapped liquid poses threats of bacteria and pyrogen growth that are disastrous in a sterile environment or healthcare application. The combination of weight that will clear away particulate, with the low viscosity and surface tension getting them in and out of miniature spaces quickly, makes solvents an ideal agent for any medical equipment or electronic cleaning. Cleaning fluid can be tailored for the application, so that even delicate, intricate parts are cleaned with consistent results. 

While environmental regulations are still in place, the concerns around solvents are no longer what they once were. In fact, modern solvents are greatly minimising environmental issues; properly designed and maintained vapour degreasers are extremely environmentally progressive. These modern, nonflammable solvent cleaning methods are making a major impact on short- and long-term reliability and performance of medical electronic equipment and devices, while lowering costs at the same time. 

If efficacy alone wasn’t enough, the solvent liquid is indefinitely reusable when it regenerates itself in the heated vapour degreaser. The thermodynamics of the heated machine generates vapour that rinses, condenses back to liquid against refrigerated coils and overflows back into the boil sump, creating a self-recycling system. Properly handled, solvents never wear out or need to be replaced.

The bottom line benefit
In an industry where the smallest margin of error could mean a critical outcome, and validation of processes, equipment and suppliers have long-term implications for manufacturer operations, choosing the right cleaning solution is more important than most would think. As medical electronics continue to advance the way that we provide care, more manufacturers will be investing in the most dependable cleaning solutions to guarantee their effectiveness. Armed with more effective cleaning agents, manufacturers’ hands aren’t tied by cleaning limitations, and they can be more empowered in their product design and innovation to focus on utility and functionality. Advances in solvent technology in combination with vapour degreasing will continue to prove themselves reliable and of increasing value.

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