Title of Invention

A METHOD OF MANUFACTURING A PLASTIC FILM CAPACITOR

Abstract

The present invention relates to a method of manufacturing a plastic film capacitors and plastic film capacitors manufactured thereof. According to the present invention a manufacturing process of the plastic film capacitor involves spreading solder material using a hot soldering iron on the welded ends of the capacitor coil to get larger contact area and improved mechanical strength this particular process step is called as swagging. It improves the tan delta band width and band height of a plastic film capacitors, and avoid arcing and open circuiting during its use and enhance the life of a plastic film capacitor. It provides improved reliability through better high voltage withstanding capability and increased current carrying capacity during operation. 11 1 OCT 2

Full Text

FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & PATENT RULES, 2003 COMPLETE/ SPECIFICATION (See section 10 and rule 13) 1.TITLE OF THE INVENTION: A method of manufacturing a plastic film capacitor ______ — (a) Name : CTR Manufacturing Industries Ltd. (b) Nationality : Indian Company (c) Address : El, Chikalthana, AURANGAHAD-431210, MAHARASHTRA, INDIA FIELD OF INVENTION The present invention relates to a method of manufacturing a plastic film capacitor and a plastic film capacitor manufactured thereof More particularly it relates to a method of Swaggjng done after welding/soldering of leads by spreading solder using a soldering iron on the welded ends of a wound capacitor coil, to increase the contact area, thereby reducing the band width of Tan delta exhibited and improving the electrical characteristics of aplastic film capacitor and eliminating lead breaking problem. BACKGROUND AND PRIOR ART DESCRIPTION Manufacture of the presently available plastic film capacitors involves the steps of: a Winding of the capacitor coil; b. End spray metallisation; c. Welding of terminals on to the end sprayed (metallised) wond capacitor coil; d. Encapulatin of the coil; e. Sealing ofthe coil with welded/soldered leads by ©poxy It is observed in such a plastic film capacitor that after short period of use, the welded lead/terminal contacts get weakened and due to which the capacitor does not exhibit desired perameters. Generally following problems are observed in such capacitors: 1. Loose contact/weakened welded leads 1 Arcing occurs at the loose contact/weakened lead wires 3. Possibibilityofcapacitorexhibiting open circuit 4. Poor electrical characteristics 5. Reduced current carrying capacity 6. Wide tan delta bandwidth resulting in overheating Shortened life 2 It is observed that plastic film capacitior fails during operation due to above mentioned drawbacks. In manufacturing of Plastic film capacitors after winding and end spray metallisation, termination/leads are welded by current welding method or soldered After welding the coils are encapaulated and sealed with epoxy. It is observed that lead breaking in the main problem of welded capacitor coils and tan delta band width of such capacitor is very high and the electrical characteristics and Insulation Resistance are poor. Also cracking noise is heard during High Voltage testing. It is therefore necessary to obviate the above mentioned drawbacks of the prior art capacitor and to improve accordingly. All the above prior art systems discuss regarding welding/soldering on capacitor coil and are not disclosing disadvantages such as arcing at high voltage, loose contact, slowly becoming open circuit, less current carrying capacity and wide tan delta band width leading to overheating in a plastic film capacitor. Hence it if necessary to provide a plastic film capacitor that will obviate all the problems as discussed above. OBJECTIVE OF THE INVENTION The objective of the present invention is to produce a plastic film capacitor that will eliminate the aforesaid drawbacks associated with the prior art capacitor manufacturing process. The primary objective of the present invention if to provide a plastic film capacitor with improved lead contacts and increased lead strength by swagging process namely spreading of solder using a soldering iron on welded capacitor coil ends. Another objective of the present invention is to provide a plastic film capacitor with low and width of tan delta as compared with the prior art plastic film capacitor. Another objective of the present invention is to provide a plastic capacitor with better electrical characteristics and improved strengths of the terminations/leads. Yet another objective of the present invention is to provide a plastic film capacitor in which arcing and open circuit will be avoided dnrmg iti operational life. Yet another objective of tie present invention is to provide a plastic film capacitor with longer life. Yet another objective of the present invention is to provide a plastic film capacitor which wil exhibit higher current carrying capacity during operation. Yet another objective of the present invention is to provide a plastic film capacitor which wil provide higher reliability during operation. Yet another objective of the present invention is to provide a plastic fllm capacitor which will not exhibit cracing noise during high voltage surges. Yet another objective of the present invention is to provide a method of manufacturing a plastic film capacitor to achieve aforesaid objects. Accordingly a new method for manufacturing a plastic film capacitor comprising of; a. placing under a vacuum a plastic dielectric film and depositing a thin layer of metal alloy as an electrode on it; b. winding a a metallead film into a cylinder to form capacitor coil sach that a metalised edge extends on each end of the wound capacitor coil; c. beatiag the capacitor coil obtained at step (b) in air ventilated oven at temperature of 110°C for 5 hrs.; 4 spraying both ends with small droplets of molten metal that adhere and make contact with the metallisation on the films; e. Welding terminations/lead wire to this end sprayed metallised coil. f. Spreading solder material using a soldering iron on the welded ends to get large lead contact area and; g. Encapsulating and sealing the capacitor coil obtained at step (f). Also this invention provides a plastic film capacitor manufactured by the aforesaid method of thepresent invention, BRIEF DESCRIPTION OF THE DRAWINGS: Figure 1: showing wound capacitor coil. Figure 2: sbowing cross sectional area of wound capacitor coil Figure 3: showing wound capacitor coil with end spray metallisation. Figure 4; showing wound capacitor coil with end spray (metallisation) and termination welded. Figure 5: allowing wound capacitor coil with solder material spread at the welding spot to get large terminal contact area and improved strength according to present invention. Figaro 6: showing flow chart of the process of present invention. Figure 7a: Shows the Gaussian curve showing tan delta value at 1 KHz of the prior art plastic film capacitior Figure 7b; Shows the Gaussian Curve showing tan delta value at 1KHz of the plastic film capacitor of present iinvention. 5 DETAILED DESCRIBTION OF THE INVENTION The above, and other object features and advantages of the invention will become apparent from following description read in conjunction with the accompanying drawings. Meaning of the reference numerals used in the drawings are as follows: l.-Wound capacitor coil 2.- Electrodes 3." Dielectric film 4.- End spray metalisaition S.-Leadwires 6\- Welding contact 7.- Solder material 8. Solder material spreaded area. According to present inventions, plastic film capacitors are manufactured by winding into a cylindrical shape any plastic dielectric film metallised on one side/both sides forming the electrode. Fig 1 shows n wounded capacitor coil( 1 ). Fig2 shows the cross sectional area of a wound capacitor coil( 1). As shown in figuere2 elctrodes( 2) are placed between dieelectric films (3) After winding, capacitor coils ( 1) are kept in air ventilated oven for heat treatment up to 5 hrs. at upto 110°C and then end spray (metallisation)(4) is done for termination contact. Fig 3 shows a capacitor coil with end spray metallisation. Then the lead wires/termination ( 5) is welded to the ends of the sprayed coil for making termination contact Figure 4 shows the wound capacitor coil with end spray metallisation and termination welded. Basically the termination wires (5) and weldmg contacts ( 6 ) are shown in figure 4. After this solder material (7) is spread by means of a soldering iron manually on welded leads (5) of the capacitor coil(l) to get large lead contact area. The soldering material (7) may be with flux or withoutflux. 6 TH the spreading step involves using a hot soldering iron the capacity of which is dependent on the amount of solder to be melted to adequately cover the entire coil and face and spread easily. This process is called swaging Such a capacitor coil is shown in figure 5. Then this capacitor coil is encapsulated and sealed. All these above mentioned steps are shown in flow chart form in figure 6. Example: Following examples will show how a plastic film caacitors manufactured by method of present invention is superior in respect of the tan delta bandwidth property compared to capacitors available in the prior art. These examples must be taken only for an explanation purpose and it does not to be taken as a restriction to the present invention. The examples have been illustrated by means of the Gaussian curves showing tan delta bandwidth for both prior art plastic film capacitors and plastic film capacitors according to present invention. Examples 1; - Example 1 is illustrated by means of figure 7a. Now referring to figure 7a shows the Gaussian curves showing tan delta bend width for prior art plastic film capacitors. On X-axis tan delta values is taken and on Y-axis number of capacitors is taken. For plotting this graph first the plurality of prior ait capacitors are taken. Then tan delta values are recorded for each capacitor at 1 KHz frequency using HelwetPackard LCR bridge or tan delta meter. Here tan delta means power loss angle. From these values the curve showing in figure 7a is drawn. As shown in figure 7a the tan delta bandwidth for the prior art capacitors obtained is in the range from 60xl04 to 95xl04. 7 Example 2: Now referring to figure 7b shows the Gaussian curve showing tan delta bandwidth for the plastic film capacitor manufactured by the method of the present invention. For plotting this curve same procedure is adopted which has been adopted in respect of the carve of the tan delta bandwidth of the prior ait capacitors. As shown in figure 7b the tan delta bandwidth for the capacitor obtained is ranges from 30x1-4* to 60x10-4. After going through example 1 and example 2 indicating the values of tan delta band width is respect of prior art capacitors and capacitors of the present mvention respectively that the value of tan delta bandwidth obtained in respect of the plastic fihn capacitors of the present invention is much lesser than the values obtained in respect of the prior art capacitors. These examples show how a plastic fihn capacitor manufactured by the method of the present invention are superior in respect of the tan delta bandwidth property than the capacitors available in prior art. ADVANTAGES OF THE INVENTION 1. The present invention improves the lead strength and the contact area by swagging ie. spreading of solder by soldering iron on welded capacitor coil 2. Another advantage of the present invention is the improved bandwidth of tan delta (loss angle) and band height of the tan delta (loss angle) of a plastic film capacitor by swagging- 3. Yet another advantage of the present invention is that arcing and open circuit during operation and use of capacitor is avoided the lift of a plastic film capacitor is enhanced. 4. Yet another advantage of the present invention is improved reliability of the plastic film capacitor through better high voltage withstanding and good currant carrying capacity during operation. INDUSTRIAL APPLICATION: Plastic film capacitors of the present invention are used in electronic as well as electrical industries. It is useful in various electronic and electrical circuits when high voltage withstanding capacity as well as better current carrying capacity is required and also when good response of the plastic film capacitor at higher frequency is required. The present invention is not limited to the above described embodiments, and various alterations, modifications, and/ or alternative applications of the invention an possible if desired, without departing from the scope and sprit of the invention which can be read from the claims and the entire specification. All these possible attentions, modifications, and or alternative applications of the invention an also intended to be within technical scope of the present invention. 9 WE CLAIM: 1. A method of manufacturing aplastic film capacitor comprising: a. placing under a vacuum a plastic dielectric film and depositing a thin layer of metal alloy as an electrodes on it; b. winding a metallised film into a cylinder to form a capacitor coil such that a metallised edge extends on each end of the wound capacitor coil; c. heating the capacitor coil obtained at step(b) in air ventilated oven at temperature of 110°C for 5hrs; d. spraying both ends of the capacitor coil with small droplets of molten metal that adhere alone & make contact with the metallisation on the film; e. welding lead wires/termmations to the end sprayed (metallised) portion of the capacitor coil for malkng termination contacts; f. spreading solder material using a soldering iron on the wdded ends of the capacitor coil to get large lead contact area, and; g. encapsulating and sealing said capeatoor eod obtained at step (f). 2. A plastic film capacitor manufactured by the method as claimed m claim 1. 3. A method of manufacturing a plastic film capacitor as herein before described with reference to accompanying drawings. 4. A plastic film capacitor as herein before described with reference to accompanying drawings. For CTR Manufacturing Industries Ltd. Date of 01st October, 2007 Mr.A.P.Knmar (Managing Director) 10

Documents:

403-mum-2007-abstract(01-10-2007).doc

403-mum-2007-abstract(1-10-2007).pdf

403-mum-2007-abstract.doc

403-mum-2007-abstract.pdf

403-mum-2007-cancelled pages(1-10-2007).pdf

403-mum-2007-claims(granted)-(01-10-2007).doc

403-mum-2007-claims(granted)-(1-10-2007).pdf

403-mum-2007-claims.doc

403-mum-2007-claims.pdf

403-mum-2007-correspondence(1-10-2008).pdf

403-mum-2007-correspondence(ipo)-(18-9-2007).pdf

403-mum-2007-description (complete).pdf

403-mum-2007-drawing(1-10-2007).pdf

403-mum-2007-drawings.pdf

403-mum-2007-form 1(1-10-2007).pdf

403-mum-2007-form 18(1-10-2007).pdf

403-mum-2007-form 2(granted)-(01-10-2007).doc

403-mum-2007-form 2(granted)-(1-10-2007).pdf

403-mum-2007-form 3(1-10-2007).pdf

403-mum-2007-form 9(1-3-2007).pdf

403-mum-2007-form-1.pdf

403-mum-2007-form-18.pdf

403-mum-2007-form-2.doc

403-mum-2007-form-2.pdf

403-mum-2007-form-3.pdf

403-mum-2007-form-9.pdf

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