JPH0582377A - Manufacture of flyback transformer - Google Patents

Abstract

PURPOSE:To provide the manufacturing method, of a flyback transformer, wherein a coil is impregnated sufficiently with a resin and it is not required to prepare for a case separately. CONSTITUTION:A coil 4 which has been wound on a bobbin 2 is vacuum- impregnated with a resin 5 which does not contain any inorganic filler. Then, the bobbin 2 and the coil 4 are set on a metal mold in a transfer molding machine; they are covered with a resin 6 which contains an inorganic filler; an outer-package case is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a step-up flyback transformer used to obtain a high voltage power source for cathode ray tubes.

[0002]

2. Description of the Related Art Conventionally, in a flyback transformer, a bobbin around which a coil is wound is set in a case, and resin is impregnated in the coil by casting resin in a vacuum to ensure insulation. However, in the conventional manufacturing method, since the filler as the inorganic filler is contained in the resin, the filler is clogged between the wires of the coil, the impregnation becomes insufficient, or air bubbles are involved, It had the problem of a short circuit. Further, since the case is used during the casting of the resin, the process is complicated and the material cost is high. Further, it takes a long time of 5 to 12 hours to cure the cast resin at 80 to 120 ° C., which causes a problem that the case is distorted by the stress during curing and the adhesion between the case and the resin is impaired. I also have.

[0003]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to
It is an object of the present invention to provide a method for manufacturing a flyback transformer in which a coil is sufficiently impregnated with resin and a case is unnecessary. In order to achieve the above object, in the method for manufacturing a flyback transformer according to the present invention, first, a coil wound around a bobbin is impregnated with a resin containing no inorganic filler. This step is preferably carried out in a vacuum, and the resin containing no inorganic filler has a low viscosity and is sufficiently impregnated between the coil wires without entraining air bubbles.

Next, the coil and the bobbin are covered with a resin containing an inorganic filler to form an outer case. In this step, the bobbin is set in a mold, and the case is integrally molded, preferably by transfer molding or injection molding.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a method of manufacturing a flyback transformer according to the present invention will be described below with reference to the accompanying drawings. First, the transformer body 1 shown in FIG. 1 is manufactured. The transformer body 1 is formed by winding a coil 4 around a bobbin 2.

Next, the transformer main body 1 is immersed in a resin liquid containing no inorganic filler in a vacuum to vacuum impregnate the resin between the wires of the coil 4. In this case, the transformer body 1 and the resin may be preheated to 60 to 100 ° C. The resin used here consists of the following components. Bisphenol A epoxy: 100 parts by weight Silane coupling agent: 1.0 parts by weight Methyltetrahydrophthalic anhydride (curing agent): 80 parts by weight Imidazole (curing agent): 0.5 parts by weight Next, the resin is 100 to 120 parts by weight. Cure at 0.5 ° C. for 0.5-1 hour. As a result, as shown in FIG. 2, the resin 5 is coated around the coil 4.

Next, the transformer body 1 shown in FIG. 2 is set in a mold of a transfer molding machine and molded with a resin liquid containing an inorganic filler. Then, the mold resin is cured at 150 ° C. for 1 to 2 hours. The resin used here consists of the following components. Novolac epoxy: 70 parts by weight Brominated epoxy: 30 parts by weight Phenol novolac: 25 parts by weight Silane coupling agent: 1.0 parts by weight Surface smoothing agent: 0.5 parts by weight Carbana wax (release agent): 0.5 Parts by weight Silica (inorganic filler): 320 parts by weight FIG. 3 shows a state in which the resin is cured and integrated with the transformer body 1 as the outer case 6. After that, a ferrite core is inserted and fixed in the center hole 3 and necessary connections are made to complete a flyback transformer.

It should be noted that the components and the component ratios of the resin for impregnation and the resin for exterior packaging in the above embodiment are of course only examples.

[0009]

As is clear from the above description, according to the present invention, the coil wound around the bobbin is first impregnated with the resin containing no inorganic filler, so that the impregnation property is good, Insulation is improved without having to be involved. Furthermore, since the coil and the bobbin impregnated with the resin are coated with the resin containing the inorganic filler to form the outer case, there is no need to prepare another case,
The process is simplified, and the curing time of the resin can be considerably shorter than in the conventional case where the resin is cast and cured. In addition, problems such as poor adhesion between the case and the casting resin and distortion of the case do not occur.

[Brief description of drawings]

The drawings show an embodiment of a method of manufacturing a flyback transformer according to the present invention in the order of steps.

FIG. 1 is a cross-sectional view of a transformer body.

FIG. 2 is a cross-sectional view showing a state where a coil is impregnated with a resin and cured.

FIG. 3 is a cross-sectional view showing a state of being covered with an outer case.

[Explanation of symbols]

 1 ... Transformer body 2 ... Bobbin 4 ... Coil 5 ... Impregnation resin 6 ... Exterior resin

Claims (1)

[Claims] 1. An outer case in which a coil wound around a bobbin is impregnated with a resin containing no inorganic filler, and the coil and bobbin impregnated with the resin are covered with a resin containing an inorganic filler. A method of manufacturing a flyback transformer, comprising: