Currently, in electrical devices, there is a trend towards lighter, smaller, and less costly components that help to save space and reduce costs while boosting power efficiency. By that, there are higher demands for more advanced and reliable electronic circuit boards. This is particularly necessary with washing machines since they have to endure physical impacts as well as harsh environments for an average of 10 – 20 years.
A potent solution is to strengthen the protection shelf of the circuit board (PCB) with several methods: conformal coating, potting and encapsulating or low pressure molding. In this article, we will discuss Potting.
What is Potting?
Potting is the process of filling a complete electronic assembly with a liquid polymer compound, which helps to enhance its resistance to heat cycles, shocks, and vibrations and protects the device from gaseous compounds, water, moisture, and corrosive agents.
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Types of Potting compounds
There are three main kinds of potting compounds – epoxies, urethanes, and silicone. Each has its pros and cons and is suitable for particular uses.
Epoxies – Epoxies have excellent chemical resistance as well as temperature resistance up to 200 degrees Celsius. They have high dielectric strength for electrical applications and excellent strength to ruggedize components, making them ideal for use in high-voltage applications. In low temperatures, they can become brittle, and the heat of reaction and shrinkage during curing can be problematic for sensitive components. As a result, matching the reactivity and exotherm is an important consideration when selecting a material. Some low-stress potting materials on the market are intended for potting SMT-populated boards where which is an important consideration.
Urethanes – Urethanes are more flexible than epoxies in general, putting less strain on potted components. They perform better in thermal cycling applications and low-temperature environments (down to -40C or lower). These potting compounds, however, are generally less resistant to chemicals and high temperatures (above 130C). Because the isocyanate portion reacts with moisture in the air and the polyol portion absorbs moisture, urethanes can be more difficult to work with than epoxy or silicone.
Silicones – Silicones are extremely flexible and can operate at the highest temperatures. They are also resistant to a wide range of chemicals and liquid water, as well as UV light and ozone. However, they are frequently the most expensive option and may not be suitable for applications requiring high rigidity. They also have a relatively high CTE, which can cause issues in high thermal cycling applications. Platinum-cured electrical potting is the most common type because it can cure in any thickness or cross-section, but the Pt catalyst is also susceptible to inhibition by many materials, such as sulfur, amines, plasticizers, and so on, so care must be taken to ensure compatibility.
How does Potting contribute to the manufacturing of a washing machine?
Washing machines, just like other home appliances products, require continuous enhancement in technology to excel user experiences. Working on challenging condition, it is necessary to prolong washing machines’s life and enhance their performance. One of the key solutions is to strengthen the protection shelf of the circuit boards (PCB) – which monitors the whole machine.
PCB protection is not only about protection during the use process but also during the manufacturing process – in which the device must go through thermal and mechanical shock, hazards, and other external factors. When washing machines are in use, on average, one can work effectively for 10 – 20 years. This means the circuit boards must work consistently and effectively for that long.
Specifically, potting advantages to washing machines are:
- Protecting from external impacts & dangerous hazards: Potting the circuit boards provides a new protective shell against vibration, shock, voltage leaks, moisture, dirt, dust, and other hazards that could damage them. This will eventually improve the washing machine’s performance and extend the device’s lifespan.
- Improving mechanical strength: As potting means you put the circuit boards in a sturdy house, you can protect them from thermal cycles during the production and operation process.
- Enhancing insulating properties: As potting fills all the gaps in the circuit boards, it is especially helpful in ensuring the insulation between electric components on the boards.
- Improving heat dissipation: Thermal potting can rapidly and effectively conduct heat away from power components to the heat sink by filling the component enclosure with compounds absorbing and transferring heat to the heat sink.
High performance potting compound for washing machine’s PCB:
- Excellent electrical and mechanical properties
- High insulation strength, flexibility
- Good resistance to water and other chemicals
- The casting compound is UL 94 V-0 recognized as self-extinguishing having an RTI of 130 °C (UL file 302173).
- Fulfills the requirements of the Household Appliances Standard IEC 60 335 having GWFI of 850 °C and GWIT of 850 °C.
- It complies with the RoHS (2002/95/EG) and electronic waste regulations (2002/96/EG WEEE directive of the EU).
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For more information, contact us to talk with our experts in potting application:
Email: gluexpert@prostech.vn
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