KR200321317Y1 - A bobbin for a transformer - Google Patents

Abstract

A bobbin for a small high voltage transformer according to the present invention includes a low voltage terminal substrate for inserting a plurality of low voltage terminals formed on both sides of a bobbin and a high voltage terminal substrate for inserting a plurality of high voltage terminals; A rectangular parallelepiped coil winding portion between the low voltage terminal substrate and the high voltage terminal substrate to wind the low pressure coil and the high pressure coil; An opening formed inside the coil winding part such that a 'ㅌ' type ferrite core having the same width as the terminal substrate can be inserted in both directions; A coil partition wall formed on an outer circumferential surface of the coil winding unit for dividing into a low pressure coil winding unit and a high pressure coil winding unit; And a plurality of slits for dividing the high voltage coil winding part at regular intervals, wherein the plurality of low voltage terminals and the plurality of high voltage terminals are respectively inserted into the low voltage terminal substrate and the high voltage terminal substrate after injection molding of the bobbin body. The transformer bobbin is composed of a thermosetting resin material, and the coil partition is double. According to the present invention, since the transformer bobbin is made of a thermosetting resin, it is not necessary to use insert injection molding, which has a longer life and complicated process than the conventional transformer bobbin. Therefore, the transformer bobbin according to the present invention is much cheaper than the conventional one. Furthermore, the transformer bobbin according to the present invention can be more electrically insulated from the low pressure coil winding and the high pressure coil winding because the coil partition wall is doubled.

Description

Bobbin for a transformer

The present invention relates to a bobbin for a small high voltage transformer used in a back light drive inverter of a TFT-LCD and the like, and more particularly, to a transformer bobbin made of a thermosetting resin with improved heat resistance and low cost.

It is attached to electronic circuit board in electronic products such as back light drive inverter of TFT-LCD used in computer monitor or TV, and it provides high voltage in electronic circuit by receiving low voltage or converting into low voltage by receiving high voltage. A transformer that acts as a giver is usually made by winding the outer circumferential surface of a bobbin made of heat and insulating resin with a coil, and inserting a ferrite core into the bobbin wound with the coil.

A typical structure of a bobbin for a small high voltage transformer is shown in FIG. As can be seen through Figure 1, on both sides of the bobbin 10, a low-voltage terminal substrate 11, a plurality of low-voltage terminal 13 is inserted and a high-voltage terminal substrate 12, a plurality of high-voltage terminal 14 is inserted, respectively Formed. The bobbin main body between the low voltage terminal board 11 and the high voltage terminal board 12 has a coil winding part in which a low pressure coil and a high pressure coil are wound. The coil winding part having a rectangular parallelepiped shape has a hole 25 formed therein so as to insert a 'ㅌ' -type ferrite core 20 having the same width as that of the terminal board in both directions, and a low pressure coil winding part on an outer circumferential surface of the coil winding part. A coil partition 17 for dividing into 15 and the high pressure coil winding 16 and a plurality of slits 18 for dividing the high pressure coil winding at regular intervals are formed.

The bobbin for a small high voltage transformer having such a configuration is mainly manufactured using an injection molding method in which a plastic is heated and melted and injected into a mold under a strong pressure. In this case, a liquid crystal polymer (LCP) resin is generally used as the material of the bobbin. The liquid crystal polymer resin is a thermoplastic resin material having a high heat resistance temperature of 290 ° C or higher and excellent mechanical and electrical insulation properties as well as good recycling characteristics. Therefore, LCP is applied not only to transformer bobbins, but also to SIMM sockets, surface mount (SMT) connectors, relays, magnetic head bobbins, and the like.

However, the following problems exist in the transformer bobbin made of such LCP.

First, in the case of a conventional transformer bobbin using the LCP, the injection molding method in which the low-pressure terminal and the high-pressure terminal are put in a mold in advance and then injected by molding the LCP in the injection molding process. When soldering to mount and fix the completed transformer on the printed circuit board (PCB) surface, it is exposed to a temperature of about 350 ° C. If the bobbin is manufactured by mechanically inserting the terminal after injection molding, the terminal is inserted. This is because the damaged part is weakened by heat, and the terminal may come off. However, such an insert injection molding method presses a metal plate to preform the lead frame, mounts the lead frame at the correct position in the mold, and then injects material into the mold to injection mold the bobbin, and finally the lead Since a plurality of terminals are formed in the bobbin by cutting the connecting portion of the frame, there is a problem that the manufacturing process is relatively complicated and expensive compared to the conventional injection molding method.

Second, since LCP is a thermoplastic material, although heat resistance is superior to other thermoplastic materials, it has a problem of shortening its life when exposed to high temperature generated when the transformer is operated for a long time. Moreover, LCP is a relatively expensive material. Transformer bobbins using LCP can be expensive.

In order to solve this problem, there has been an attempt in the art to produce a bobbin for a transformer using a thermosetting resin which is cheaper than a liquid crystal polymer resin. However, in the case of injection molding using a thermosetting resin, since the molding is performed at a higher temperature than that in the case of injection molding with a liquid crystal polymer resin, deformation and abrasion of the mold occur during molding, and as a result, the life of the mold This will be very short. Therefore, in the case of using the thermosetting resin, there is a problem that the effectiveness is inferior rather than in the case of using the liquid crystal polymer resin.

Therefore, the present invention aims to produce a bobbin for a transformer which is cheaper and has a long lifespan by overcoming such a conventional problem. That is, an object of the present invention is to be able to produce a transformer bobbin using a thermosetting resin which is a relatively inexpensive and long-life material.

Still another object of the present invention is to provide a mold for injection molding, which is used to produce a transformer bobbin made of the thermosetting resin, and to provide a mold having a low deformation and a long life even at a high temperature.

1 is a bobbin for a transformer manufactured using a conventional liquid crystal polymer resin.

Figure 2 is a transformer bobbin prepared using a phenol resin according to the present invention.

※ Explanation of code about main part of drawing ※

10,30 .. Bobbin body 11 ..... Low voltage terminal board

12 ..... High voltage terminal board 13 ..... Low voltage terminal

14 ..... High voltage terminal 15,33..Low pressure coil winding

16,34 High pressure coil winding 17,35 Coil bulkhead

18 ..... Slit 20 ..... Ferrite Core

31 ..... Terminal insertion hole 32 ..... Slit wall

In order to achieve the above object, a bobbin for a high voltage transformer of the present invention includes a low voltage terminal substrate for inserting a plurality of low voltage terminals formed on both sides of a bobbin and a high voltage terminal substrate for inserting a plurality of high voltage terminals; A rectangular parallelepiped coil winding portion between the low voltage terminal substrate and the high voltage terminal substrate to wind the low pressure coil and the high pressure coil; An opening formed inside the coil winding part such that a 'ㅌ' type ferrite core having the same width as the terminal substrate can be inserted in both directions; A coil partition wall formed on an outer circumferential surface of the coil winding unit for dividing into a low pressure coil winding unit and a high pressure coil winding unit; And a plurality of slits for dividing the high voltage coil winding part at regular intervals, wherein the plurality of low voltage terminals and the plurality of high voltage terminals are respectively inserted into the low voltage terminal substrate and the high voltage terminal substrate after injection molding of the bobbin body. The transformer bobbin is composed of a thermosetting resin material, and the coil partition is double.

At this time, the mold for injection molding the transformer bobbin of the present invention with a thermosetting resin material is made of powder high speed tool steel, and after hardening at least about 10 hours at about 1000 ° C. or higher, the hardened powder high speed tool steel is Tempering for 6 hours at a temperature of about 600 ° C. was repeated three times.

In the case of manufacturing a plastic product, an injection molding method in which a material is heated and melted and injected into a mold under a strong pressure is mainly used. In this case, the mold used in the injection molding process is appropriately selected according to the plastic material used for molding. In the case of producing a bobbin for a transformer using a liquid crystal polymer (LCP) resin, SKD- having abrasion resistance and toughness is conventionally used. 11 or SKD-61 series tool steel was used mainly. When manufacturing a mold with such SKD-11 or SKD-61 series tool steel, after increasing the hardness by primary heat treatment, the internal stress of the metal generated in the process of increasing the hardness is reduced and the metal Tempering should be performed at a temperature of about 260 ~ 290 ℃ to stabilize the internal structure of.

Thus, the conventional transformer bobbin manufactured using the liquid crystal polymer resin has the problems described above. In order to overcome this problem, it is necessary to use a thermosetting resin instead of the liquid crystal polymer resin which is a thermoplastic resin. However, the liquid crystal polymer resin, which is a thermoplastic resin, can be injected at a temperature of about 120 ° C., so no problem occurs in the mold. However, in order to use a thermosetting resin, the injection process should be performed at a high temperature of about 350 ° C. Therefore, deformation of the mold occurs. This is because the injection process is performed at a temperature higher than the tempering temperature (260 ~ 290 ℃) to relax the internal stress of the mold manufactured by SKD-11 or SKD-61 series and stabilize the internal structure. When the mold is deformed in the injection process, not only the mold is easily worn, but also the defect rate is very high because the dimensions and shape of the product are different from those originally intended. In addition, when tempering is performed at a temperature higher than 350 ° C. in order to avoid deformation of the mold, a problem arises in that hardness and tensile strength are lowered and are easily broken. Due to such a problem, it has been difficult to conventionally manufacture a bobbin for a small high voltage transformer using a thermosetting resin.

In order to overcome this problem, the present invention manufactures a mold using powder high speed tool steel, which is a new material that has not been used in the mold manufacturing. Powder high speed tool steel, especially powder high (ASP23) has the advantage that the particles are uniformly distributed, excellent workability, good toughness and wear resistance, and small dimensional change after heat treatment.

Now, the process for producing a transformer bobbin according to the present invention is as follows.

First, a mold of a desired form is manufactured using the powder high, and then the manufactured mold is hardened for 10 hours or more at a temperature of about 1000 ° C. or more. As already explained, when the metal is hardened, internal stress is generated in the process. Therefore, when the finishing process such as grinding is performed, the balance of stress is changed and deformation or cracking can be generated, and when it is used as it is, the stress is alleviated with time and the deformation appears. In order to remove such instability of the structure, it is necessary to perform tempering after curing to reduce residual stress. Accordingly, in the present invention, a tempering treatment performed for about 6 hours at a temperature of about 600 ° C. was repeatedly performed three times. The mold manufactured in this manner has both good toughness and wear resistance, and deformation does not occur even when injection molding the thermosetting resin at a temperature of 350 ° C.

When the heat treatment for the mold of the powder high material is completed as described above, the bobbin body for the transformer is injection molded using the thermosetting resin as a material using the mold. Although various things are possible as said thermosetting resin material used here, especially a phenol resin is suitable. Phenolic resin is not only very good in electrical insulation, strength, heat resistance and acid resistance, but also relatively inexpensive.

When the injection molded bobbin body is completed, the transformer bobbin according to the present invention is completed by mechanically inserting a terminal made of a metal pin into the terminal insertion hole of the bobbin body. In the present invention, the terminal is directly inserted after the injection molding of the main body, without using the injection molding which inserts the metal frame together in the mold and injection molding. This is because the transformer bobbin main body according to the present invention is a thermosetting resin such as a phenol resin, so that even when the transformer is mounted on the circuit board by soldering, the bobbin is heated and softened so that the terminal is not connected poorly.

Figure 2 (a) and (b) shows a transformer bobbin according to the present invention, Figure 2 (a) is before inserting the terminal and Figure 2 (b) is after the terminal is inserted. As shown in FIG. 2 (a), an injection molded bobbin main body 30 is provided with an insertion hole 31 for inserting a terminal. As shown in Fig. 2 (b) showing the transformer bobbin after the terminal is inserted, the overall shape of the transformer bobbin is similar to the conventional one. However, thermosetting resins are more fragile than thermoplastic resins. Therefore, in order to prevent cracking of the slit that divides the high-pressure coil winding part at regular intervals, the thickness of the slit wall 32 is thicker than before, and the number of slits is increased. It is desirable to reduce and widen the slit width. The slit is to facilitate lamination when winding a thin coil having a diameter of about 0.04 mm at high speed, and a width of about 1.8 mm to 2.3 mm is appropriate. In the transformer bobbin of the present invention, since the coil partition 35 formed on the outer circumferential surface of the coil winding part is doubled to divide into the low pressure coil winding part and the high pressure coil winding part, the low pressure coil winding part 33 and the high pressure coil winding part 34 may be more completely electrically insulated.

As described so far, according to the present invention, since the transformer bobbin is composed of a thermosetting resin such as a phenol resin, it is stronger in heat than a conventional transformer bobbin made of a liquid crystal polymer resin and thus has a long service life. In addition, even if the terminal is inserted after the bobbin body is injection molded, there is no fear that the terminal will come off when the transformer is mounted on the circuit board. Therefore, it is not necessary to use a complicated insert injection molding process. For this reason, the transformer bobbin according to the present invention can be produced much cheaper than the conventional bobbin for transformer. Moreover, in the bobbin for a transformer according to the present invention, since the coil partition wall is double, the low pressure coil winding and the high pressure coil winding may be electrically insulated more completely.

Claims (2)

In a bobbin for a small high voltage transformer, the bobbin is: A low voltage terminal substrate for inserting a plurality of low voltage terminals and a high voltage terminal substrate for inserting a plurality of high voltage terminals formed on both sides of the bobbin; A rectangular parallelepiped coil winding portion between the low voltage terminal substrate and the high voltage terminal substrate to wind the low pressure coil and the high pressure coil; An opening formed inside the coil winding part such that a 'ㅌ' type ferrite core having the same width as the terminal substrate can be inserted in both directions; A coil partition wall formed on an outer circumferential surface of the coil winding unit for dividing into a low pressure coil winding unit and a high pressure coil winding unit; And It is composed of a plurality of slits for dividing the high pressure coil winding unit at regular intervals, The plurality of low voltage terminals and the plurality of high voltage terminals are inserted into the low pressure terminal substrate and the high pressure terminal substrate, respectively, after injection molding of the bobbin body, and the bobbin for the transformer is made of a thermosetting resin material, and the coil partition wall is composed of two layers. The bobbin for a transformer characterized by the above-mentioned. The method of claim 1, The thermosetting resin is preferably a transformer bobbin, characterized in that the phenol resin.