PAGE 6 • Paktron • P.O. Box 4539, 1205 McConville Road, Lynchburg, Virginia 24502 • Tel 434-239-6941 • Fax 434-239-4730 • www.paktron.com

Metallized Polyester (PET) Dielectric

ITW Paktron developed the highly advanced Interleaf

®

Technology method of capacitor manufacturing to improve

device electrical properties and stability in actual use condi-

tions. As opposed to the conventional winding method,

Interleaf® Technology uses a high laminating pressure,

linear stacking technology. The resulting capacitor chip is a

construction hybrid resembling a multilayer ceramic capaci-

tor in cross section, while offering all the fail-safe advan-

tages of a stacked plastic film capacitor. We refer to the

resultant parts as MLP or multilayer polymer. The Angstor®

Capacitor (or RA Style) is a self-encased, metallized film

capacitor which features small size, high dv/dt capability

and very low ESR at high frequency.

Intended for thru-hole and wired applications, the units

feature all aluminum electrodes and terminals that are pulse

welded to the lead wires. The units are back impregnated

with a microcrystalline polymer sealant, and require no

external coatings for moisture protection. The internal layers

are heavily laminated to eliminate air from the core material

which improves high frequency response compared to com-

petitive units. Operating temperature limit is extended to125

degrees C.

The following are a few examples of applications

wherein the Angstor’s unique features have

proven desirable:

HIGH FREQUENCY SWITCHING POWER INPUTS

As the modern power converter broke the 100 KHz

switching frequency barrier, the ripple voltage and RFI con-

trol components changed drastically. On the input side of 48

volt converters, a low ESR and ESL capacitor is needed in

the pi filter network to control EMI generated by the switch-

ing MOSFET. Metallized film capacitors should be used

because of the voltage bias and due to the unit’s

ability to “clear” during a high voltage event, rather than

short out like a common MLC capacitor. Electrolytic (alumi-

num and tantalum) capacitors are not useful because of

their extremely high parasitic resistance and inductance.

Under ripple voltage the Angstor is stable, while ceramic

losses.

LINE AND DATA LINE NOISE SUPPRESSION

A 250 volt Angstor will not lose value due to the bias volt-

age and can be used on higher voltage lines as a differential

noise bypass for RFI control. High input dv/dt up to 100 volts

per micro second can be handled. In modems, the Angstor

is a space efficient alternative to other input current control

devices. Since the capacitor body is “plastic” there exists no

piezoelectric emf due to input di/dt.

EMI/RFI SUPPRESSION

Noise suppression is required on a variety of motors and

field effect devices close to the offending source to minimize

RFI on the voltage bus. Noise or transients emanating from

switched state motors or inductors require a low ESR

capacitor as part of the filtering arrangement. The Angstor is

an excellent choice for these 12, 36 and 48 volt bus-rails

because of its small size compared to other film capacitors

and better ESR and reliability than ceramic capacitors. As

the automotive bus voltage rises from 12 to 36/42 volts, this

technology will replace many ceramic and tantalum capaci-

tors because of its enhanced voltage coefficient (stability).

GRACEFUL AGING

There exists no chemical interactions within the MLP

Capacitor to effect long term life. The parts are suitable

for 10 to 20 year life applications due to their stability and

inherently low loss. The polymer dielectric becomes more

crystalline over long periods of time, which can gradually

lower the capacitance value. The thin-film metallized elec-

trodes are capable of “self healing” under high voltage

events. This feature avoids the shorting, cracking and rapid

heat generation problem often found in ceramic capacitors.