Polypropylene (PP) is from a molecular point of view a non-polar dielectric with small losses and a relatively straight and moderate TC. Since the smallest film thickness is approx. 3.5 μm (0.14 mils) and εr ≈ 2.3 the capacitor can not come down to those sizes characterizing
What are the optimum soldering conditions and solder fillet? The best solder fillet for all SMT applications is one which makes a reliable connection and which best withstands the environmental exposures of the products with minimum degradation. This fillet is difficult to describe quantitatively for all parts. The optimum fillet ranges in height from about 1/3 to 2/3 of the part termination height. This does not mean that all solder joints outside of this range should be repaired. It does mean that this is the target for the process engineer to reach for in his process. As many as possible of the solder fillets on the board should be in this range.
Not only magnetic materials possess a magnetic field, but every current carrying conductor also creates a magnetic field itself.
Energy can be temporarily stored in the magnetic field. This effect is technically exploited in coils, consisting of one or more wire windings. The synonymous term “inductor” has become established.
EMC ferrites are based on Ni-Zn materials. This material has good quality factors (Q < 3) above approx. 20 MHz – i.e. trimmed for high losses. These originate in the core material and serve to absorb EMC interference. The inductance of these components is purposely kept low. Inductors however should show high quality factors, i.e. operate as loss-free as possible and buffer energy in the magnetic field. Also, they require stable inductance values over a wide frequency range. The distinction emphasized is reflected in the layout of the relevant manufacturer catalogue.
Insulation Resistance, IR
The dielectric of a capacitor has a large area and a short length. Even if the material is a good isolator there always flows a certain current between the charged electrodes (the current increases exponentially with the temperature). This leakage can be described as a parallel resistance with a high value, an Insulation Resistance (Figure: Schematic of the Insulation Resistance IR in a capacitor.). We use the abbreviation IR in the following.
Impedance and ESR
A capacitor creates in AC circuits a resistance, the capacitive reactance (Formula C1-3). There is also certain inductance in the capacitor. In AC circuits it produces an inductive reactance that tries to neutralize the capacitive one. Finally the capacitor has resistive losses. Together these three elements produce the impedance, Z.
Within the electrostatic capacitor family we can distinguish two groups: the organic film capacitors and capacitors with inorganic dielectrics. Capacitors with ceramic materials belong to inorganic dielectrics family