Dielectrics, Cathodes, Cases, Carrier Tapes and Binders

• Dielectric materials for both AC and DC film capacitors
• Cathode layers for low ESR electrolytic capacitors
• Molding and dipping materials for solid case electrolytics>/li>
• Carrier tape for ceramic chip capacitors
• A binder agent for tantalum and ceramic powder.

Paumanok estimates the combined value of plastic material consumption in the capacitor industry at approximately $1,300 million USD in 2007 (Fiscal Year ending March).

DIELECTRIC MATERIALS:

Our findings reveal that polypropylene and polyethylene terephthalate represent more than 90% of the global volume of film consumption for capacitor dielectrics. Consumption of polypropylene for use in AC film capacitors has grown substantially since 2003 because of their use as power factor correction capacitors in a variety of line voltage devices. Demand for PET film has remained flat during the same time period because of the movement to surface mount film chips and the encroachment of NPO type MLCC on the traditional 5 mm PET film capacitor market.

Polyphenylene sulfide and polyethylene naphthalate are growing markets for films consumed in capacitors because of their use in the surface mount “chip” versions of DC film capacitors.

The greatest promise for the industry between 2007 and 2014 will be in the use of large film capacitors (requiring 2 to 9 pounds of dielectric film per capacitor) for the DC Link in hybrid electric vehicles (primarily for passenger cars and class 7 and 8 trucks). Polypropylene has been the choice for this application to date, but other film dielectrics may be employed for this application in the near term as well.

The following is information about each plastic dielectric film:

Polypropylene:

Polypropylene (PP) is used for AC power factor correction, pulse discharge and interference suppression applications (electrical). Primarily Bollore, Toray and Treofan supply this material to the capacitor industry. Polypropylene is a preferred dielectric because of its abundant supply and relatively stable price.

Polyethylene Terephthalate:

Polyethylene Terephthalate (PET) is used for DC filtering applications (Electronic). Primarily SteinerFilm and Toray Industries supply this material to the capacitor industry. The capacitors that consumed PET film are being encroached upon by alternative technology (the NPO type high capacitance ceramic chip capacitor). Still this market is quite large, with film capacitor sales in the many billions of pieces, so regardless of their small size (mostly 5mm in diameter), the resulting volume of film required is substantial. Also the higher priced Du Pont Mylar®, which is the choice film for this application, makes the price of the metallized version about twice the price of polypropylene film.

Polyphenylene Sulfide:

Polyphenylene Sulfide (PPS) is used for ultra-small PPS film chip capacitors for filtering applications in DC circuits. This material is supplied primarily by Toray Industries to the capacitor industry. It is manufactured into capacitors primarily by Panasonic. The PPS film chip capacitor market is gaining share and taking away some business previously serviced by the 5 mm PET film capacitors. PPS dielectric film is the result of a joint development effort by Phillips and Toray Industries Inc. of Japan. The price of the film is very expensive; however, the volumes required to produce capacitors is lower than that of PET because of the chip formats produced (mostly 1206 and 0805 case sizes, which are minute compared to a 5mm PET film capacitor). The material has excellent chances for continued growth because of its high heat handling capabilities, its proven track record in finished capacitors, and its ability to withstand rigorous soldering cycles. Both its capacitance and voltage handling capabilities are limitations in the finished capacitor, and its high price makes it a target for new film introduction for high heat handling dielectrics.

Polyethylene Naphthalate:

Polyethylene naphthalate (PEN) is used for ultra-small PEN film chip capacitors for filtering applications in DC circuits. Primarily Du Pont/Teijin to the capacitor industry supplies this material. It competes against PPS in the DC film chip capacitor market segment. It is a lower cost alternative to PPS, but does not have the ultra-high heat handling capabilities of the more expensive PPS film. The inability for PEN to withstand extremely hot and fast soldering cycles limits its acceptance in some applications. It still is a growth business because of its greater product offering in terms of capacitance and voltage when compared to PPS.

Polycarbonate:

Polycarbonate (PC) film sales to the capacitor industry ended when Bayer AG, the former PC supplier to the industry discontinued production of the film. This film is important to note because it had the highest average price paid per pound for any film dielectric. It has been reported that this film must be spun on a stainless steel wheel to achieve thicknesses required for capacitor winding.

Polystyrene:

Polystyrene has also been consumed in the capacitor industry, primarily to meet U.S. military specifications that govern the use of these capacitors in defense electronics. Polystyrene can be metallized by Birkelbach for the capacitor industry.

Polysulfone:

Polysulfone has electrical properties that are similar in performance to polycarbonate capacitors with a very good temperature coefficient and higher operating temperature capabilities for the finished capacitor. The film is sold in either metallized or unmetallized form. This material is rarely used in capacitors now because of the limited availability of thin polysulfone film.

Polytetrafluoroethylene:

Polytetrafluoroethylene (PTFE)-Teflon is also a rarely used capacitor film dielectric. The film is biaxially orientated to achieve the highest capacitance. Teflon® film capacitors are used when high heat and precision are the two governing criteria for the capacitor circuit. A Teflon® capacitor is operational up to 120ºC. PTFE material is also sold to the supercapacitor industry as an extruded dielectric by W.L. Gore & Company (not included in this report).

Polyimide:

Polyimide (PI)-Kapton® is also used in exotic capacitors consumed in extremely high heat and harsh environments, primarily for defense applications (aircraft electronics, and space electronics) The volumes are low and, this material like Teflon®, is rare.

Siloxane:

Siloxane: Siloxanes are a class of organosilicon compounds with the empirical formula R2SiO, where R is an organic group. Representative examples are [SiO(CH3)2]n (dimethylsiloxane) and [SiO(C6H5)2]n (diphenylsiloxane). Siloxane is manufactured into capacitors by TPL, Inc. of ABQ New Mexico. These prototype capacitors are consumed in high energy density defense related markets. It has some interest as a DC link capacitor material for hybrid electric vehicles.

Polyvinylidene Difluoride:

Polyvinylidene Difluoride, or PVDF, is a highly non-reactive and pure thermoplastic fluoropolymer. It is also known as KYNAR® or HYLAR®. It is used generally in applications requiring the highest purity, strength, and resistance to solvents, acids, bases and heat and low smoke generation during a fire event. It does, however, have a very low melt point. This material is also rarely used in capacitors, but has been consumed in the past for high voltage, one shot, high density capacitors. This material has been sold to the capacitor industry in the past by Rhone-Poulenc of France.

Aromatic polyester (FPE):

Aromatic polyester (FPE): This material has been suggested by 3M to be used in capacitors in the past (circa 1995) because of its high heat handling capabilities. Paumanok knows of no prototype capacitors manufactures from this film in 2007.

CATHODE MATERIALS: CONDUCTIVE POLYMERS

Opportunities Abound: Plastic material is consumed in additional applications in the capacitor industry and many are rapid growth markets. These include the use of polythiophene and polypyrole materials as the cathode layer in tantalum chip and solid polymer aluminum capacitors. In these electrolytic chip designs, the “conductive” polymer is replacing manganese layers to improve the equivalent series resistance of the capacitor. The process involves one of two methods. One, whereby the capacitor anode is dipped into repeated liquid baths of monomers and oxidizers and finished with a sealer (Polyanaline). Or another method (used mostly in Japan) whereby the cathode layer is created by applying the polymer material via a pressurization technique. Electrolytic capacitors that use conductive polymers as their cathodes are growing at a much faster rate than capacitors that employ traditional materials (such as manganese, or etched foil).

CAPACITOR CASES:

Plastic materials are also consumed as the packaging material for tantalum chip capacitors and solid polymer aluminum capacitors. In these segments, plastics are consumed in the form of epoxy (or polyepoxide - most common epoxy resins are produced from a reaction between epichlorohydrin and bisphenol-A.) materials (primarily from Loctite/Dexter) to give the ultra small capacitor a robust mechanical nature and to protect the anode. These processes involve bringing the component, which is to be coated to a sufficient temperature to ensure thermosetting of the pulverulent plastic material.

BINDER MATERIALS:

Additionally, plastic binder materials – mostly polyvinyl acetate (PVA) are consumed in the production of tantalum metal powder and barium titanate ceramics. The binder is introduced during the processing of the powder into an anode, and then is burn-out completely during the sintering process. Binder materials have become more important as of late in the capacitor industry because the speed by which they burn out may improve the surface area of the anode.

CARRIER TAPE:

And plastic “carrier tape” is consumed in the production process for ceramic chip capacitors. Carrier tape is a thin (primarily polyester or polypropylene is used; even plastic coated aluminum in some applications) film that pulls the wet ceramic dielectric through the multilayered ceramic chip production process. The carrier tape is removed and discarded during the production process.

TERMINATION MATERIALS:

Ceramic capacitor manufacturers (e.g., AVX and Novacap) have introduced soft terminations manufactured from silver doped epoxy resin. These new terminations, which are being applied primarily to the massive 1 trillion piece ceramic chip capacitor industry, are designed to help printed circuit board stuffers to pass the rigid “flex-test.” Traditional terminations are made from metal (copper, silver), and can be damaged during this process, especially when there is a high concentration of MLCC on a small board.

Outlook for Plastic Materials: 2007-2014

Overall growth for plastics consumption in the capacitor industry, which is considered by the major plastics vendors to be a value-added, or engineered technical plastics business is good. Leading the way in growth will be polypropylene because of its almost exclusive use in power factor correction for line voltage electronics. Other growth areas will be in PPS and PEN films because of their use in surface mount type film chip capacitors. Conductive polymer applications, which include both polythiophene and polypyrole will also continue to grow because of the safe nature of the cathode and its improved ESR when compared to alternative materials. Carrier tape markets for wet process MLCC will also grow due to the massive increases in volume each year for MLCC capacity worldwide. Epoxy materials hold promise for growth too, primarily as a termination material; but also for consumption in tantalum chip cases and solid polymer aluminum capacitor cases.

For further information regarding market research into plastic material supply to the capacitor industry, visit www.paumanokgroup.com; or call Dennis Zogbi at 919 468-0384.