Copolymer Binders and Their Use in Tape Casting Applications

AZoM talks to Peter Ferraro, Director of Business Development at Empower about the benefits of QPAC® Poly(alkylene Carbonate) Copolymer Binders about their advantages when used in tape casting applications.

Can you just explain about Empower Materials?

Empower Materials has been operating for over 25 years now. The products that we produce are polyalkylene carbonates, which we call QPAC®. These products are broken up into several different types. We have QPAC® 25, which is a polyethylene carbonate, QPAC® 40, which is polypropylene carbonate, and then we have QPAC® 100, which is polypropylene cyclohexene carbonate, and then we have QPAC® 130, which is polycyclohexene carbonate. We also have what we call QPAC® polybutylene carbonate, which is our newer product.

Which markets that these products primarily serve?

All those products serve various markets, but primarily they are used as either a binder or as a sacrificial material, meaning a binder to hold some type of powder together in a green state, such as a ceramic powder, a glass powder, or a metal powder. When you are forming some type of shape, either by pressing or tape casting for instance, you need a binder to hold those fine powders together, and QPAC® serves as the binder in many applications where you have requirements of final products that can't tolerate any type of contamination in the final product, which would be left behind by the binder if it doesn't burn out cleanly. Equally, if you have powders that are very sensitive to temperature, you can burn out our binder at a lower temperature. The markets that it serves are quite varied, however, a current focus of ours is electronic market. Particularly passive components. Forming passive components either by pressing or tape casting and using our binder to form that green state is one of our bigger markets.

Are there any other markets that you are focused on?

We are also in inks, paste, for instance glass sealing paste is a big market for us. Where you are taking glass and you are making a paste for sealing parts for some application, whether it's sensors or plates of some type for energy applications. QPAC® is also used in what we call brazing application, for making brazing parts and brazing paste. That is a big application for us. But, QPAC® is also used in medical applications, aerospace applications, HVAC applications. Numerous types of applications! Also, we see interest in 3D printing applications as part of the component going into the inks that are used to form the shapes. We see a lot of interest in battery applications, for the electrolyte; a lot of different numerous markets.

Image Credit: shutterstock.com/Andrii Zhezhera

Can you just explain what tape casting is?

With tape casting, you start with a powder, in this case a ceramic powder. It does not have to be ceramic powder, it can aslo be a metal powder. To form that film, you use a tape caster. You have a fine powder, in this case it is ceramic, and you add the powder into a solvent to form it into a liquid. You add a binder to hold the powder together when you cast it. This mixture is called the slip.; the powder, the binder, and the solvent. Then you flow that slip onto a conveyor. You spread out the slip with a doctor blade to form a sheet. The thick liquid is controlled by the doctor blade. The sheet, which is a wet or a thick liquid, gets spread out on the caster and then it is dried. The solvent is removed and you end up with a sheet that is primarily the powder, which is cast into the sheet and the binder holding the powder together.

How is tape casting used for producing electronic passive components?

Well, for the most part, the electronic passive parts have a dielectric component. The dielectric can be a ceramic. Each layer of ceramic is usually laminated to form the dielectric part. Each laminated component is cut to form the dielectric part of the capacitor, or the passive component. The thickness of each layer that is required of that dielectric, which will vary for every type of ceramic capacitor, is determined by the doctor blade and the initial stage of the tape casting process.

What are the advantages of using QPAC®?

The tape is a polymeric matrix embedded with the ceramic particles. Essentially, the particles are being held together by the polymer, in our case it is QPAC®. That sheet has to have good properties, has to be flexible so you can handle it. Has to be strong so it doesn't break. You do not want it to be brittle because then you would not be able to form shapes out of it. QPAC® has good mechanical properties so it does make a strong tape. It is flexible, has a lower glass transition temperature (T_G) which prevents it from being brittle. It has good mechanical properties, but for the most part the advantages are its decomposition properties. After you made that green tape you have to get rid of the binder because it is not in the final product, it is just a temporary adhesive.

With the QPAC®, you have several advantages. For instance, it is important that the dielectric does not have any contaminants in the final product because it will affect the electrical properties. With QPAC®, when it burns out, there is no carbon left behind. You will end up with improved electrical performance. As the capacitors get thinner, the cof contaminants becomes more of a factor, more of a problem. With QPAC®, you can get thinner dielectric layers and still maintain good properties. In LTCC type capacitors, the binder usually needs to be decomposed in an inert environment. Many binders cannot decompose in inert environments, or if they do, all of the binder cannot be removed. With QPAC® you can remove all the binder in inert environments. It is not a problem. It burns out just as cleanly in inert environments as it does in air, which is rare for a binder. So, that is an advantage.

With a lot of these parts, some of them are actually thicker, bigger parts. The QPAC® burns out more easily than other binders at a lower temperature so as a result with thicker parts you end up with less cracking in the final product because it is easier for the binder to escape from the part. Since the QPAC® decomposition process is more efficient, the furnace efficiency is improved. So, your furnace utilization can go up where you can save on that.

Lastly, it also burns out at a lower temperature, so you can debind at lower temperatures. Sometimes you have other materials in the tape, which may be affected by higher temperature. For instance, glass, which could melt at a lower temperature, and as a result the binder can get trapped into the tape. Or, you could have some  components in the tape that are sensitive to higher temperatures.  The QPAC® can burn out as low as 170-180 °C within the tape, which is an advantage.

Where can our readers find our more?

Well, there is information on our website, empowermaterials.com. You can contact us directly, our number is 302-225-0100 and extension 1. We can support any questions that you have or you could direct it to our email, which is [email protected]. Or myself, [email protected].

About Peter Ferraro

Working for Empower Materials for 11 years as Director of Business Development. Responsible for commercializing QPAC® polyalkylene carbonates in technical markets worldwide. Earlier work experience involved focusing on new business development of emerging technologies in nanoparticles, energy and digital imaging.

Educational background includes undergraduate degree in Chemical Engineering Degree from Columbia University and masters degree in Business from Lehigh University.