Capacitor manufacture

Several manufacturers of ceramic powders are involved in commercializa tion of hydrothermaHy derived powders. In the United States, Cabot (Boyertown, Peimsylvania) has built a small manufacturing plant and is supplying materials to capacitor manufacturers. Other manufacturers include Sakai Chemical and Euji Titanium in Japan. Sakai Chemical is reportedly producing 1 t/d in its demonstration plant. A comparison of the characteristics of commercially available powders is given in Table 2. 

Wire. Tantalum wire is used primarily as the anode lead wire in soHd tantalum capacitors. Since the 1970s, the average weight of tantalum in a sohd tantalum capacitor has dropped from several hundred milligrams to less than 50 mg but the consumption of tantalum powder for capacitors has remained relatively constant because of the dramatic increase in the number of capacitors manufactured. The weight of wire per capacitor has remained relatively constant and thus wire consumption has increased steadily. 

Determine the discharge device for the discharge of a three-phase 6.6 kV, 50 Hz, 1000 kVAr, yconnected capacitor bank, connected in units of 10 x 100 kVAr each, through an automatic p.f. correction relay, having a closing cycle of 10 seconds. Data available from the capacitor manufacturer,... 

Capacitor manufacturers have only begun to specify the use of their capacitors in high frequency switching power supplies. One must use care when reviewing capacitors for use in one s power supply. The ESR should be specified at a frequency greater than 1 kHz. 

This causes the control-to-output characteristic to add gain and phase above the location of this zero. This can be a problem with respect to the stability of the supply. Unfortunately, many capacitor manufacturers do not present the value of the ESR for their capacitors. Typically, the zero caused by the output filter capacitor falls in the following range ... 

The main reason for the tantalum industry s drive toward the sodium reduction process is an increasing demand for tantalum powder by tantalum capacitor manufacturers. The modem tendency of the electronics industry to miniaturize their components calls for the improvement of tantalum powder... 

Capacitor manufacturers recommend that in general we don t pass any more current than the maximum rated ripple current. This ripple current is the one specified at the worst case ambient (e.g., 105°C). Even at lower temperatures we should not exceed this current rating. No temperature multipliers should be used. Because only then is the case to core temperature differential within the design specifications of the part. And only then are we allowed to apply the simple 10°C doubling rule for life. 

Also note that capacitor manufacturers typically do not guarantee life under forced air cooling. The designer should either measure the capacitor without forced air cooling if possible, or add some judicious safety margin. 

An update of a retrospective cohort mortality study of 2588 US workers exposed to PCBs in two capacitor manufacturing plants found a statistically significant excess for cancer of the liver and biliary passages [5 observed vs. 1.9 expected, standardized mortality ratio (SMR) 263]. Both Aroclor 1254 (54% chlorine) and 1242 (42% chlorine) had been used at... 

A significant excess risk of death from malignant melanoma (8 observed, 2.0 expected) was observed in a cohort study of 3588 capacitor manufacturing workers exposed to Aroclor 1242 and then 1016." ... 

Acquevella JF et al Assessment of clinical, metabolic, dietary, and occupational correlations with serum polychlorinated biphenyl levels among employees at an electric capacitor manufacturing plant. J Occup Med 28 1177-1180, 1986... 

Case Studies of Minimization of Solvent Waste from Parts Cleaning and from Electronic Capacitor Manufacturing Operations, (NTIS PBB7-227D1 J). 

Figure 17.3 Stand alone sub-micron PZT capacitors manufactured by FIB etching...

Nami, R.B., Capacitor manufacturers face challenges in the next century, Ceram. Ind., December, 28, 1997. 

With the exceptions of quartz and emerald, the typical crystals grown hydrothermally are small. There is no inherent reason for this. Hydrothermal synthesis of fine powders of barium titanate and similar dielectric materials is of importance in capacitor manufacture. 

Application of Valve Metals in Electrolytic Capacitor Manufacturing 1.3.4.1 Capacitor Fundamentals... 

There are many further important process details for Ta metal powder (TaMP) production that can not be disclosed here, and which are the object of continuing R D work. It should be mentioned that Nb capacitor grade metal powder can be produced in a method similar to the second route using the aqueous Nb solution mentioned above. Some further information can be found in Ref. [237-247]. Once the TaMP is finished it can be used by the capacitor manufacturer to produce the capacitor devices. Briefly, the following process steps are used in a conventional production line ... 

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