The increasing miniaturization of next-generation medical devices demands smaller and more intricate electronic components to be incorporated into the 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 a complex reduced space.

How do we achieve reliable electronics and manage faults of miniature components with ever-tighter tolerances? One solution recognized as a method to help assure reliability is through quality cleaning. Improved cleaning directly translates to more reliable printed circuit boards (PCBs), and therefore, to better medical electronics.

When looking to outsource the manufacture of electronic medical devices, cleanliness standards and processes should be a top consideration to ensure products do not fail.

A Growing Market Calls for Effective Cleaning Processes
The global medical device outsourcing market size was valued at $104.5 billion in 2019 and is expected to grow at a compound annual growth rate (CAGR) of 10.4 percent from 2020 to 2027. There are a number of reasons for this growth. They include increasing demand for medical devices like implantable medical electronic devices to help manage the rising prevalence of chronic diseases. Also, some companies are shifting their focus to research and development and outsourcing the manufacturing of their medical devices.¹

This escalation in the production of medical electronic devices brings with it the problem of maintaining reliability. Medical device manufacturers have to ensure their products can be produced efficiently to meet the required time to market, while guaranteeing they have long-tern reliability. Medical electronics—for example, implantable devices like pacemakers—cannot malfunction. The result could be catastrophic if specific standards and processes are not put in place.

Processes for device reliability should be established at the very early stages, preferably within planning. One of the most important procedures to consider to attain consistency is the cleaning process. PCBs in medical electronic devices are instrumental to their function. It is therefore important to ensure they work without fault. Although often overlooked during initial planning, effective cleaning can help achieve consistency and is a critical consideration when designing the PCB.

Miniaturization Makes Contamination Control a Challenge
One of the biggest reasons for PCB failure is contamination resulting from the manufacturing process. Contamination comes in many forms: simple dirt, dust, or oil from a fingerprint, or rosin residue on the circuit board. All of these are classified as non-ionic contamination—non-conductive molecules that can remain on the PCB surface after assembly.

Contamination also comes in the form of ionic contamination, which is most typically flux residue left behind during PCB manufacture or after the soldering process. It normally consists of inorganic salts or acids and is commonly seen as “white residue” left on the circuit board. This ionic residue contains molecules that are conductive when in a solution. If exposed to levels of moisture, the ionic residue can split into negatively or positively charged ions, increasing the solution’s overall conductivity. If left untreated, it will progressively degrade and may lead to corrosion and dendrite growth causing leakage and short-circuits. Any contaminant on the PCB can threaten the board’s functionality and result in device failure.

What makes contaminant removal even more challenging is medical electronic devices’ increasing miniaturization and design complexity. Medical device technology must often be portable, compact, and lightweight. This means designing electronic devices with densely-packed and extremely complex circuitry.

Miniaturization causes a greater likelihood for insufficient, weak solder joints, bridging, and dendrite growth. It is important to find a cleaning process that removes contaminants efficiently and successfully to meet strict regulatory testing and standards and ensures reliability.

Vapor Degreasing: The Answer to Cleaner Electronics
Vapor degreasing is a cleaning method that is helping to ensure medical electronic device reliability. It is important when outsourcing manufacturing of medical electronics that the applied cleaning method is investigated and specific procedures are stipulated to certify its effectiveness. The process of vapor degreasing not only guarantees the device’s cleanliness, but also satisfies the regulatory conditions required for medical component manufacturing.

Vapor degreasing is a thermo-mechanical process that boils and condenses a specially-designed low-boiling non-flammable cleaning fluid. A vapor degreasing machine contains two chambers—a boil sump and a rinse sump. In the boil sump, the cleaning fluid is heated and parts are immersed and cleaned in the fluid. Once cleaned, the parts are mechanically transferred into the rinse sump for final rinse in a pure, uncontaminated fluid.

The cleaning fluids used in the system have multiple chemical properties that are advantageous to critical cleaning. For example, they typically have a low surface tension and a very low viscosity, allowing them to easily penetrate and clean very tight spaces like blind holes and under the smallest of parts. Most vapor degreasing fluids also are very heavy and dense—typically 20 to 40 percent heavier than water. This aids in dislodging particulate from components, an important factor when cleaning intricate miniaturized PCBs.

Critical for electronic medical devices, vapor degreasing can handle the most challenging and complex shapes with the parts coming out clean, dry, spot-free, and immediately ready for further processing.

Furthermore, the process ensures validation can be achieved successfully. Validation helps ensure electronic medical devices and all parts within them, like the PCBs, consistently meet set quality standards. Because vapor degreasing cleaning is a simple, predictable, and repeatable process, it is easy to qualify and validate for medical device manufacturing.

Meeting Manufacturing Standards
Medical electronics are unique in that they may be used in the human body. They face strict regulation guidelines concerning design, manufacturing, and certification. Medical electronics have no 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. The International Organization for Standardization (ISO) is one regulatory body that must be adhered to in order to produce medical electronics. There are a number of ISO standards to follow, for example ISO 10993. This evaluates devices within a risk management framework to ensure they are safe, assessing bioburden, pyrogens, and sterility to ensure no harmful material remains on the device and the device is safe for its intended use.

Another benchmark standard that must be met is IEC 60601-1. Specified by the International Electrotechnical Commission (IEC), this regulation is explicitly designed for medical electrical equipment and systems. It necessitates maintenance of a medical device’s basic safety and essential performance. Cleaning is one of the central practices to help meet this requirement.

These examples are just the tip of the iceberg. There are many other standards and regulations that must be followed, including those specific to PCB cleanliness. A validated and reliable cleaning regime is critical.

Stipulate Your Cleaning Requirements Before Outsourcing
The cleaning processes put in place when designing and manufacturing electronic medical devices are critical to their reliability. Functionality will be compromised if cleaning processes are not designed to be consistent, validated, and efficient.

When outsourcing any electronic production, verify the electronics manufacturing service (EMS) provider has experience in meeting regulatory requirements such as those embodied by the IEC and ISO and stays compliant without cutting corners when it comes to cleaning. Research how the products will be cleaned and stipulate your own specification and quality control standards. This helps to give transparency of the cleaning processes used to qualify and validate electronic medical device manufacturing and ensure reliability.

For companies looking for help in selecting the correct cleaning processes, it is essential to work with a partner that has expertise in cleaning medical electronics and understands the strict regulations governing cleanliness. Based on specific part makeup and contamination encountered, a knowledgeable partner can recommend the sustainable cleaning fluids and methods that will work best. 

Reference

1. bit.ly/mpo102001

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Jay Tourigny is senior vice president at MicroCare Medical, which offers medical device cleaning and lubricating solutions. He has been in the industry more than 30 years and holds numerous U.S. patents for cleaning-related products that are used on a daily basis in medical and precision cleaning applications. For more information, visit www.microcaremed.com.