Key Polymer’s Tough-Seal solves common potting compound problems: cracking from temperature changes, vibration damage, and heat generation during large pours. Their R&D focuses on customer needs and industry standards, offering technical support and testing resources. Learn more at

John Maher: Hi, I am John Maher, and I’m here today with Melissa Mitchell, 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 Key Polymer and your potting needs. Welcome, Melissa.

Melissa Mitchell: Hey John, how are you? It’s really great to be here and good to talk to you again.

Solving Challenging Customer Problems with Potting Compounds

John Yeah, you too. So, Melissa, in terms of Key Polymer, what are some unique stories that you have that might involve solving some challenging customer problems using your potting compounds?

Melissa: Yeah, there’s definitely a few that we can talk about today. I think one thing that I do want to mention though before we really get into some specifics is a lot of times, the customers that we work with and we have a pretty supportive tech team that does help customers with exactly challenges like you said. And a lot of the applications that come in are definitely unique. Tough-Seal is a little bit of a different niche-type product, potting compound. It’s different than a lot of products on the market. So we definitely see a lot of different issues with applications that come up.

What’s really been unique, especially since I’ve been here, John, is that potting compounds are selected by customers and there’s some thought that goes into it, but it’s usually an after the product is developed thought and we end up being the solution for fixing failed failures, which is kind of unique. So we are the choice from the beginning in many instances, but a lot of times we have been the choice to fix a failed failure or even a customer recall. So we’ve had several customers that have selected Tough-Seal when their parts are recalled, they use Tough-Seal to fix that recall. And it’s kind of neat to get involved with the customer at that point. They end up being a long-term customer, but it’s very exciting and really great to be able to help resolve a problem.

John And is that generally like the case where they’ve used a different potting compound and it fails and then they’re coming to you because your potting compound, Tough-Seal solves an issue that they had with their other potting compound? Or is it a case where they just didn’t even use a potting compound at all and that’s why their electronic components failed?

Melissa: Yeah, it seems to be that most of the time they pick the wrong potting compounds. So for example, we had an automotive sensor manufacturer and a refrigerator sensor manufacturer reach out to us because their parts obviously are in the thermal cycling, hot-cold, hot-cold, hot-cold situation. So, if you have a harder potting compound, like a lot of epoxies and urethanes on the market, they’ll be put into an application in seal a sensor, and then they’re going to see cold temperatures for refrigeration or automotive and then hotter temperatures as the system heats up, then it could get cold again, hot again. So you see a lot of that up and down and that will cause the harder potting compound to crack over time. And then once those potting compounds crack, water moisture, like I had mentioned the last time we spoke, the water and moisture can get into these sensors, and it causes the sensor to fail.

So, these customers went for the potting compound that seemed like it was going to be harder and more durable when they actually needed something more flexible and non-cracking. So like I said, Tough-Seal is more of a niche product. It is different than everything else. Hardness ranges from pencil-eraser hardness to car tire hardness, so some flexibility, no real change in dimension, no shrinkage, anything like that in the part so you don’t see cracking with Tough-Seal. So when you put the potting compound over the electronic components, you get a really good seal that is stable with those temperature changes. And like I said, the recall was major and the new parts were prepared or manufactured with Tough-Seal. They didn’t have to worry about cracking moving forward and totally resolved that issue with moisture ingress or water ingress into their sensor. And they were great for future applications. And these customers remained Tough-Seal customers and realized that this was a better choice for that thermal cycling application.

Using Tough-Seal with Heavy Vibration

John Okay. What other examples do you have?

Melissa: Yeah, so we have an issue that comes up a lot as vibration. Some customers will see that over time, vibration, again, harder potting compounds will crack or it can cause even delamination. A lot of times when a sensor or a control or electronic component is potted, it’s potted in a housing. So almost like a box that goes around the circuit board or around the sensor. And then you pot inside the box to create a sealed part with vibration that feel to the outer housing or outer box can delaminate and you can see again cracking, especially in a heavy duty truck or heavy duty equipment, there’s a lot of vibration that goes on. So we had a manufacturer reach out to us, they told us about their problem in the field. Again, it was causing a lot of dust… It was an issue because it was a heavy-duty equipment and that dust was building up and the sensor, the boards are overheating and they were seeing some issues with failures with their sensors.

So, Tough-Seal definitely was recommended. We sent them an evaluation kit, they did some testing on their end just from a performance and reliability standpoint, recognize that from a vibration, that kind of “rubber seal” that was going around their components kind of moved with the vibration as opposed to against the vibration. And definitely didn’t see failures with their solder joints, they didn’t see failures anywhere across the board once they potted with our Tough-Seal, more flexible, more last American, better for vibration problems for sure.

Eliminating Exothermic Reactions with Potting Material

John Okay. And then do you have one more example?

Melissa: Sure. The last example, an EV manufacturer. So electronic vehicle manufacturer, they were potting, the charger connector, the part that plugs into your vehicle and that part requires… It’s a pretty big part. The circuit board is in that actual handle. And the material quantity required is about a pound of potting compound, which is a pretty significant amount of potting compound. And typically, when potting compounds react, they give off heat and exotherm. And that heat causes problems because it builds up, can cause damage to the board, especially as that hot potting compound cures cools and shrinks. You can pull components off the failures at solder joints and it’s just problematic across the board.

This EV manufacturer came to us. There were a requirement for no exotherm. Our Tough-Seal does not exotherm when it cures even in large masses. So a pound of potting compound, no heat is generated when it cures. It’s a pretty benign cure. And when the Tough-Seal was given for them to do some testing on, they were really impressed with the no exotherm, no shrinkage and they ended up converting over to Tough-Seal. They knew they weren’t going to see any embedment stress or cracking or field failures by using our Tough-Seal. So that was definitely a really great transition for them. Again, solving a problem though, that’s kind of been our claim to fame, fixing field failures in recalls, which has been great.

Research & Development at Key Polymer

John So it sounds like Tough-Seal really does a lot of things that lot of other potting compounds don’t do. What’s the research and development process like at Key Polymer? Can you give us a little bit of an insight into that in terms of how you’ve designed and developed your potting compounds?

Melissa: Yeah. So we take a lot of ownership and pride into developing new products, doing extensive research to ensure that formulations are compatible with electronic requirements. Mechanical thermal and electrical property requirements are reviewed to real-time applications. Customer feedback is super critical to us. So past and present customer feedback is always considered for new product development. We had several customers that had used our Tough-Seal in the past, which is obviously a flexible elastomeric epoxy hybrid potting compound and it is black and we’ve had several LED lighting customers say, “hey, we want Tough-Seal but in a clear version. And we would like it to do this, or we were hoping that it would have the same hardness as Tough-Seal 21.”

So, we definitely listened to our customers. We developed a product which we offer today, it’s our Klear-Seal 82 and looking at all of the feedback from our customers property-wise, any obstacles that customers have faced, we’ve definitely taken a lot of that feedback to develop even our Tough-Seal 21, which is our newest version of Tough-Seal, it is a polycarbonate compatible Tough-Seal that has a much longer shelf life, more stability than our existing product line. So definitely, I think customer feedback is critical to where we’re moving in our progression to develop new products. And again, with all of that in mind, keeping in mind also compliance and regulatory requirements, things change every day from what chemicals are blacklisted or going to be blacklisted, what meets reach compliance for our customers in Europe, RoHS compliance for customers across the board, Prop 65. So, all of this is under consideration when we’re developing material. And we do extensive qualification and reliability testing just to make sure that we are meeting industry requirements.

Support and Resources Offered by Key Polymer

John And beyond just the products that you manufacture, what other support and resources does Key Polymer offer to help Key Polymer customers, especially in terms of choosing the right potting compounds, etc.?

Melissa: Yeah, so we have a pretty strong technical support team that does provide support to customers. We want to make sure that customers pick the right potting compound for their specific application. We do have extensive data available to assist them and we have our evaluation kit that we offer to customers. It does allow the customer to perform their own reliability testing and qualification testing. And then our in-house lab can also support some of the technical requests that come in.

We do have a full-service lab and if project… if it makes sense for Key Polymer to help support customer projects, we certainly would embrace doing that for sure. But it’s really sharing all of this information, making sure we select the right product for the customer is critical, especially after discussing some of the failures that can be seen if the wrong potting compound selected. We definitely like to make sure for starting new projects that we are really working with the customer to understand them and make sure we have the right material for them.

Get More Information About Key Polymer

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

Melissa: Yeah, my pleasure. It was great to be here.

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