This guide helps you choose the right potting compound. It covers key properties, shelf life, and balancing conflicting needs. Industry standards and long-term performance prediction are explained. Key Polymer’s innovative compound is resistant to cracking and shrinking.

John Maher: Hi, I am John Maher, and I’m here today with Melissa Mitchell, a product manager and senior engineer at Key Polymer, a manufacturer of electronic potting compounds, adhesives, coatings, and other chemical compounds. And today we’re discussing choosing the right material, properties, and considerations. Welcome, Melissa.

Melissa Mitchell: Hey, John. Great to be here. Thanks.

Surprising Properties of a Potting Compound

John: Sure. So, Melissa, when you’re selecting a potting compound, what are some of the most surprising properties to consider and why might those be overlooked?

Melissa: So, there are so many properties that are important, and different properties are important for different customers and different applications. So it’s kind of hard to dial those things in specifically. Typically, gel time, viscosity, hardness are all very important so that you’re able to pot your part and go over your components, and it flows correctly over them. And the final product is the correct hardness. And then thermal stability is important from ensuring that application temperature-wise is not going to harm your components or your board. And those are all really important to consider.

But I think one of the most important things to consider that people don’t really think about until after they select a potting compound is what package is this product available in? So for example, is the product available in pails? Is it available in drums? Is it available in easy-to-use cartridges? And certain potting compounds might only be available in a quart kit or a five-gallon kit or a drum kit. But packaging and the delivery system are really important because if you’re potting really small parts, you don’t necessarily want to use a system that’s feeding from drums because it’s more of a… maybe you might have more of an automated system for drums, or you might have more of a larger part that you’re potting or something like that.

Customers that I have sometimes might only use a dime-sized amount of material, and they’re not able to invest in a capital project that is going to get them an automated system. So there’s workers on a line that are doing potting themselves, and they have to dispense a dime size quantity of material into a board or onto a sensor.

So, availability of potting compounds in cartridges is really important. Tough-Seal, for example, and Tough-Seal Ultra, they’re available in 50 milliliter cartridges, which are a smaller, very manageable, easy-to-use size. They’re also available in 400 milliliter cartridges which is a little bit bigger and a little bit bulkier, but still more manageable from a manual assembly line. And then bulk containers are important for somebody who may have more of a mass production setting or more of an automated setting where they’re going to invest in a meter mix system that’s going to allow them to dispense from pails or allow them to dispense from drums.

So, looking at what the packaging and availability of the product from the beginning is sometimes overlooked, but I think it’s really important to know that from the beginning, especially depending on what exactly you’re potting and what size part you’re potting.

What is the Shelf Life of Potting Materials?

John: Right. Is there a shelf life on the product as well so that you don’t want to buy too much and have it just sitting around for months and not getting used, something like that?

Melissa: Yeah, so the shelf life on the product varies from product to product. Some of our materials have a three-month shelf life at room temperature, but can be stored frozen for up to 12 months to extend the shelf life. So that’s one possibility. Some things have a 12-month shelf life at room temperature and are stable. And then our new Tough-Seal Ultra actually has an 18 to 24-month shelf life at room temperature. So you can plan purchasing and buying bulk quantities around shelf life. And with the different shelf life and storage capabilities, it makes the whole shelf-life issue more manageable to ensure, again, like you said, that you’re not buying more product than what you’re going to use. Everybody today is really very focused on waste and minimizing waste. So, you absolutely want to make sure that what you’re ordering is what you need, and you’re not going to have any excess waste and product that is going into landfills or anything like that.

Balancing the Needs of Different Properties in Potting Compounds

John: Right. How can customers balance the maybe opposing needs of different properties that they’re looking for in a potting compound? Maybe they need something that has high thermal conductivity but low flammability, and they can’t find that in the same potting compound. Are there any clever workarounds that you have for things like that?

Melissa: So, from a workaround standpoint, I think the biggest thing that I’ve seen is not necessarily something that customers would know to balance, but for example, different fillers when we’re developing have multiple functions. So there are times that we’re developing something for one application or for one property, I should say, but in the end, it’s going to offer other properties as well. So for example, we have some UL-listed products, which are flame retardant, UL94V-0 which is self-extinguishing, and they are filled with a filler that also not only gives it flammability resistance, but also provides thermal conductivity.

So, it’s something that kind of was a clever workaround in the formulation of it. It’s beneficial to customers. So sometimes a customer will call and say, “Hey, I need a flame-retardant material.” And we’ll say, “Yep, this will fit, our Tough-Seal 41 and 42, those are the products that you need.” And then other customers will call and say, “Hey, I need thermal conductivity, but I know sometimes with flame retardants it’s difficult to have properties that will fit both instances.” Our specific Tough-Seal 41 and 42 will do both of those things. So sometimes fillers, like I said, can be used from a development level that will contribute properties that are opposing, but in the end, will “work together.”

Industry Specific Standards or Certifications

John: Are there any industry-specific standards or certifications that listeners should look for when they’re choosing a potting compound?

Melissa: Specifically, sometimes there’s UL certifications that are required, and then there’s some compliance certifications from RoHS to REACH to Prop 65. We have a really robust system that we can take our formulations, and we run it through to be sure that we are checking the compliance with specific changes that happen regularly with compliance and certifications. So from that standpoint, we try to ensure that we’re always at the top of understanding where our products fall in the development standpoint.

We use this tool to make sure that when we’re developing things, we’re selecting things that are going to meet UL requirements in those instances and that are going to meet certification requirements in those instances. So, I think the listeners should really work with, for example, our technical team to map out exactly what they need for requirements, and then we would help them hand-select a product that would work for their specific needs.

Long-Term Performance of a Potting Compound

John: And how can we predict the long-term performance of a parting compound over time, especially given factors like aging and environmental stresses?

Melissa: So, the biggest long-term performance prediction is usually through reliability testing. So there’s usually a test. There’s some ASTM standards that we follow. There are other tests that we work with customers to make sure that the testing that we’re doing or testing that we have done aligns timeline-wise with a long-term factor for environmental stress or environmental aging. And this reliability testing can be 2000 hours in an 85 C chamber with 85% relative humidity and see how the product performs over time. Or it can be thermal cycling testing from -40 C to 150 C. And you do that testing over a profile of so many hours and so many days and confirm that the product going in at the beginning is the same product coming out after the end of testing.

So, reliability testing is definitely the answer. There are some instances when you don’t always have a procedure for reliability testing, but try to find something close to it or something that your customer may suggest or recommend that may “mimic” the actual environmental exposure or stresses that are going to be seen over time. And then that testing would be performed in the lab to confirm that, again, the product going into the test is the same product coming out of the test.

Advancements from Key Polymer

John: Okay. And are there any specific advancements that you feel like Key Polymer has made that has really revolutionized the area of potting compounds?

Melissa: I think that the whole concept of a hybrid elastomeric potting compound that doesn’t crack, doesn’t exotherm, doesn’t shrink, I think that has been for us and our success with our products, that has definitely revolutionized the properties of potting compounds because of they’re a unique set of detailed properties that we know have resolved issues with other customers that have seen recalls and failed failures with standard hard potting compounds that crack over time. So, I think the whole concept of our flexible elastomeric potting compound is exactly what you’re asking me about for sure.

How to Learn More About Key Polymer

John: All right. Well, that’s really great information. Melissa, thanks again for speaking with me today.

Melissa: Thanks, John. It’s great to be here, and I’m looking forward to talking with you again.

John: Absolutely. And for more information, you can visit the Key Polymer website at keypolymer.com or call 978-683-9411.