Modern methods to cleaner medical electronics assemblies

15th October 2019
Posted By : Joe Bush
Modern methods to cleaner medical electronics assemblies

The increasing miniaturisation of next-generation medical devices is demanding smaller and more intricate electronic components to be incorporated into their design. Although a benefit to patients thanks to the reduced size and weight of the devices, the electronic assemblies must still deliver the same performance within more complex and tighter spaces. Emily Peck, Senior Chemist at MicroCare Corporation explains.

These technological advancements in medical electronic devices have generated industry growth. The medical electronics market was valued at $3.01bn in 2015 and is expected to reach $4.41bn by 2022. The demand for advanced healthcare solutions has played a prominent role in the growth of the medical electronics market worldwide.

With this growth comes the requirement to ensure devices work effectively and reliably. However, the increasing use of miniature components with ever-tighter tolerances, makes managing faults problematic and challenging. One solution recognised as a method to help assure reliability is through quality cleaning. Improved cleaning directly translates to more effective PCBs, and therefore to better medical electronics.

Components used within medical devices require not just long term functionality, but they must also stand up to rigorous regulations put in place by governing bodies. All of these factors are adding pressure to manufacturers looking to produce superior miniaturised medical devices. Cleaning is a critical step to the assurance that medical electronic components will work effectively. Almost all medical devices require cleaning during manufacture to remove particulate, oils or inorganic contamination resulting from the manufacturing process. The challenge is to identify a process that is suitable for the critical cleaning of complex assemblies, intricate shapes and delicate parts.

Vapour degreasing
Above: Vapour degreasing not only ensures the cleanliness of the device, but also satisfies the economic and regulatory requirements needed within medical component manufacturing

In the medical electronics industry, the process of cleaning compact PCB configurations can be difficult. Consideration has to be given to the solder joints found within these devices. If defective they can cause a large percentage of PCB failures, so removing any harmful contaminant and residue is key to their success. Advanced modern cleaning methods enable engineers to specify stronger, more active fluxes, which results in better solder joints, eliminating problems with cold joints, insufficient wetting, bridging, and shorts. However, these more robust fluxes can be more difficult to clean.

It is predominantly because of this challenge that the acceptance of vapour degreasing as a PCB cleaning alternative is growing. Many companies are beginning to realise the benefits of this tried and tested PCB cleaning application.

Vapour degreasing - a tried and tested method 

The processes used in the development and manufacture of medical electronics devices offer no room for error. For this reason, a vapour degreasing system using advanced cleaning fluids is one of the most reliable cleaning methods.

Vapour degreasing not only ensures the cleanliness of the device, but also satisfies the economic and regulatory requirements needed within medical component manufacturing. Medical device companies value safety, quality and reliability in order to minimise liability and maximise performance and profits. Many of the challenging production and performance issues can be reduced with the correct cleaning of the PCBs and mechanical medical assemblies using the vapour degreasing process.

Vapour degreasers offer a simple process that is effective at removing contaminants. The low viscosity and surface tension ratings of modern cleaning solvents used in a vapour degreaser, combined with their volatility, allow them to clean very effectively, especially under low surface mount components like QFNs or D-Paks. For medical device designers, this means they are not limited in product design. Vapour degreasing ensures all surfaces of the PCB will be effectively cleaned and free of contamination.

Because modern cleaning fluids evaporate so quickly, the vapours are easily removed from small, tightly packed printed circuit boards where slow-drying solvents either could not clean or could be trapped. Additionally, there are no unacceptable residues left on a component once it has been cleaned making it ideal for cleaning super-critical applications.

Reducing validation risk 

When it comes to medical electronic devices a significant concern is the risk of bioburden. This is when bacteria remain on a surface that has not been sterilised. This can be problematic within the cleaning process, particularly if the cleaning method uses aqueous technologies as water is a primary growth medium for bacteria. Even a minimal amount of moisture in hard-to-reach areas can aid the growth of bacteria. It is therefore preferred to completely remove water from the cleaning process to minimise this threat. If it is not properly addressed, it can result in increased complications during the validation of the product and issues with the reliability of the device.

This is one of the principal reasons why solvent cleaning is becoming the preferred choice. Solvent-based cleaning fluids are hostile to pyrogens, so vapour degreasing greatly simplifies process control requirements for eliminating bioburden. When parts are cleaned in a vapour degreaser, they exit the machine immediately and are dry, further eliminating the risk bioburden.

Addressing environmental concerns 

Some of the biggest challenges affecting how medical electronic devices are cleaned are environmental concerns, new regulatory requirements and pressures for a healthy workplace. Modern cleaning fluids used in a vapour degreaser have outstanding ecological and safety profiles. There are non-toxic, environmentally acceptable and highly effective cleaning options that out-perform older fluids and out-dated processes like aqueous cleaning.

Modern cleaning formulations have been developed to clean very effectively inside a vapor degreaser without the use of harmful chemicals like HCFC-225, nPB and TCE, all of which retain substantial ground water contamination and air quality concerns.

Modern critical cleaning processes
Above: Modern critical cleaning processes like vapour degreasing present new solutions for manufacturers in the medical electronics industry

Unlike aqueous cleaning, a vapour degreaser uses no water, therefore, saving natural resources. In addition, vapour degreasing fluids boil at a low temperature, so it takes little electricity to clean and completely dry components before additional processing or packaging. Plus, modern vapour degreasing fluids can be recycled and reused for thousands of hours before it needs to be refreshed, reducing waste and disposal costs.

Advances in solvent technology have led to cleaning solutions that not only deliver consistent cleaning but are also gentler on the planet as well.

Weighing up your options

Medical device manufacturers’ concerns are changing for a number of reasons. The trend towards smaller more advanced electronic devices, coupled with tighter governmental requirements and environmental regulations can stop designers and engineers in their tracks. When designing and manufacturing electronic devices for the medical industry, quality and reliability considerations are vitally important. Critical cleaning is helping with these production objectives.

The challenge is to find a process that will not only clean small highly complex parts effectively, but also addresses all the other concerns from environmental impact and worker safety to bioburden risk and cost implications. Thanks to innovative developments in cleaning fluids and technology, manufacturers are finding solutions that not only answer all these concerns but offer impressive cleaning results.

Modern critical cleaning processes like vapour degreasing present new solutions for manufacturers in the medical electronics industry. Progressive next-generation cleaning fluids allow for better PCBs to be built and deployed, therefore creating new capabilities for the future of medical electronics.

Top image: A vapour degreasing system using advanced cleaning fluids is one of the most reliable cleaning methods

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