How to use resins: Potting guide
Table of Contents
Every month, we will be exploring the complex world of resins where we will be looking at the main reasons for using Huntsman Araldite resins in encapsulating and potting compounds.
This month’s article will focus on the fundamental chemical compositions, how each resin type differs from one another and their individual properties that can be exploited to maximize performance in a wide range of environmental conditions.
Why, where and how to use resins to make a potting for electronics?
Now, let us start with moisture; the main enemy of electrical and electronic equipment where apart from causing short circuits can also lead to premature deterioration of components due to corrosion.
Resins can provide an answer to this problem.
Polyurethane resins: typically supplied as two part products and when mixed achieve the desired curing and resistance to critical moisture. Amongst excellent electrical insulation, flexibility and good adhesion to most substrates.
Some compounds of polyurethane encapsulated provide outstanding resistance to seawater and extreme temperatures. Ideal for marine industry, such as encapsulation applications.
A good example of an outdoor encapsulated component polyurethane resin requiring maximum protection against water ingress is a LED unit; these resins are also optically clear and UV stable, making them ideal for the task.
The resin moisture cure polyurethane is available as a single component, but these are not-not whether to achieve moisture resistance and penetration of moisture is necessary for complete curing potting or encapsulation.
Some resins epoxy also provide good moisture resistance and faster cure speed, hardness and high stability, particularly in environments of varying temperature.
They also adhere well to most substrates, including difficult substrates with a very low surface tension such as PTFE, ensuring watertight encapsulation.
2) Chemical protection
So what next? It may also be necessary to protect electrical or electronic components, which may be exposed to chemicals, including acids, alkalis, solvents and a number of other substances that pose a threat to the circuits and delicate components.
The chemical resistance is very much the province of epoxy resins, although some hard polyurethane products – as well as some silicone formulations base- provide a degree of protection.
Epoxy resin products are available to protect electronic / electrical units, which undergo frequent or permanent immersion in solvents such as diesel fuel, gasoline and leaded and unleaded cellulose diluents.
3) Mechanical shock
Another key point is the importance of protecting the components of mechanical shock and vibration.
Here, a more flexible cured product is likely to provide the best solution because it adds a level of compliance that will help you isolate the components in pots against adverse mechanical movements.
In addition to its moisture resistant resins, polyurethane properties also provide a desired level of flexibility, making it the first choice for protection against shock and vibration.
Silicone resins also provide excellent flexibility and will tolerate high operating temperatures.
One more ‘shock’ I should mention is the shock, thermal which can have a devastating effect on electronic components, shortening its operating life, at best destroying them completely at worst.
The adverse effects of thermal stress can be improved by using epoxy resins of two parts, which are better for those applications that are subjected to severe or cycles are prone to thermal shock temperature.
Some also offer the added benefit of flame retardant technology.
Finally, it is worth mentioning that apart from providing all the aforementioned protections, potting and encapsulation resins conceal what is underneath.
This could provide an effective foil counterfeiters or those who wish to copy a track layout that helps you protect your intellectual property.
Summary on how to use resins
When it comes to the choice and application of resins, there a lot more to discuss, and over the next months I hope to provide some useful hints and tips to help you in your quest for more optimal protection circuit.