JP2014116126A - Chip type fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the formation of sulfide even if a metal that is easily sulfided is used for a fuse element, and to use a silicon resin layer as a protective layer.
A fuse element formed on an insulating substrate (2) is in contact with a nickel layer (15) deposited on an upper surface (4) of the insulating substrate (2), a copper layer (16) deposited on the nickel layer (15), and the copper layer (16). The nickel layer 18 covering the copper layer 16 and the nickel layer 15 is in contact with the fuse layer, and the silicon resin layer 22 covers the fuse layer.
[Selection] Figure 1

Description

  The present invention relates to a chip-type fuse mounted on a printed circuit board, and more particularly to a fuse layer containing a metal that is easily sulfided.

  Conventionally, for example, there is an electronic component as disclosed in Patent Document 1 as a mounting type electronic component. The electronic component of Patent Document 1 is a resistor, which is provided with two upper surface electrode layers on a substrate, a resistance layer is provided so as to electrically connect the two upper surface electrode layers, and the two upper surface electrode layers described above. A separate upper electrode layer is provided on each of them, and an epoxy resin layer is provided as a protective layer so as to cover the different upper electrode layers and the resistance layer.

JP 2000-188456 A

  A chip-type fuse may adopt the same configuration as that of the resistor of Patent Document 1, but in this case, the resistance layer is a fuse element, but a metal that easily generates sulfide in the fuse element, for example, copper When using a chip type fuse in a sulfide atmosphere, copper causes a chemical reaction with a sulfide factor to form copper sulfide by using an epoxy resin that is hard to permeate gas and moisture in the protective layer. It is difficult to prevent the life from being shortened. However, when an epoxy resin is used as a protective layer, since the heat resistance is low, discoloration and alteration of the epoxy resin occur, and in the worst case, ignition and smoke generation occur. Further, the arc extinguishing function when the fuse is blown is low, and the persistence of the arc and the residual resistance after the blow are lowered due to the alteration of the epoxy resin or the like, making it difficult to obtain sufficient fuse properties.

  An object of the present invention is to provide a chip-type fuse that can obtain sufficient fuse characteristics while preventing the formation of sulfides while using a metal that is easily sulfided for a fuse element.

  The chip-type fuse of one embodiment of the present invention includes an insulating substrate, and a fuse layer is formed on one surface of the insulating substrate. This fuse layer is a metal layer that is easily sulfided, such as a copper layer, a silver layer, or an alloy of copper and another metal, an alloy of silver and another metal, and nickel that covers the metal layer in contact with the metal layer. And a layer. The nickel layer is not only in contact with one surface of the metal layer, but also covers the side surface of the metal layer. A silicon resin layer covers the fuse layer in contact with the fuse layer.

  In the chip type fuse constructed in this way, since the nickel layer is covered with a metal layer that is easily sulfided, even if this chip type fuse is used in a sulfurized atmosphere, the metal layer causes a chemical reaction with a sulfide factor. Difficult to form sulfides. As a result, the lifetime of this chip-type fuse can be increased. Furthermore, the problem of sulfide formation can be solved even if a silicon resin layer that easily allows gas or moisture to pass through is used as the protective layer. The silicon resin layer has excellent heat resistance compared to the epoxy resin layer, and also has a high arc extinguishing function when the fuse is blown, and the arc discharge can be extinguished. Can be. In addition, since the silicon resin layer is softer than the epoxy resin layer and has a strong shock buffering action during the fuse operation, it is suitable as a protective layer for a chip-type fuse.

  In the above aspect, a low melting point metal layer may be formed on a part of the nickel layer of the fuse layer. As the metal of the low melting point metal layer, for example, tin, indium, bismuth or lead can be used. If comprised in this way, the alloy of the metal of a low melting-point metal layer and nickel will be formed with the temperature when a fuse layer fuses, a fuse layer will aggregate on the both ends, and a residual resistance can be made high.

  In the above aspect, another nickel layer may be interposed between the metal layer and the one surface of the insulating substrate. If comprised in this way, it can prevent that the sulfidation factor osmose | permeates the said metal layer side from the insulated substrate side, Furthermore, the lifetime improvement of the said metal layer can be achieved.

  Furthermore, an electrode having another copper layer electrically connected to the copper layer can be provided. This other copper layer can also be connected to the nickel layer. This other copper layer is also covered by another nickel layer. With this configuration, the copper layer formed as an electrode is also less likely to permeate the sulfide factor when the chip-type fuse is exposed to the sulfurized atmosphere, and the lifetime of the chip-type fuse can be increased.

  In the above aspect, an electrode having another copper layer electrically connected to the copper layer can be provided. This other copper layer can also be connected to the nickel layer. This other copper layer can also be covered by another nickel layer. In this case, an epoxy resin layer can be formed between the nickel layer of the fuse layer and the other nickel layer. With this construction, the epoxy resin layer can prevent the sulfide factor from penetrating into the copper layer from the gap between the nickel layers, and this nickel resin layer or another copper layer can be formed. It can also be used as a mask when performing.

  As described above, according to the present invention, even if a metal such as copper, silver, or an alloy thereof that is easily sulfided is used for the fuse element, the formation of sulfide can be prevented, and the protective layer or arc extinguishing material layer can be prevented. It is possible to use a silicon resin layer, and sufficient fuse characteristics can be obtained.

It is a vertical side view of the chip type fuse of one embodiment of the present invention. It is an AA end view of FIG.

  The chip-type fuse of one embodiment of the present invention has an insulating substrate 2 as shown in FIGS. The insulating substrate 2 is formed in a substantially rectangular parallelepiped shape with an insulating material, and has an upper surface 4, a lower surface 6, end surfaces 8 and 10, and side surfaces 12 and 14 shown in FIG. 2.

  A nickel layer 15 is deposited as a fuse element on the entire surface of the insulating substrate 2, for example, in the center of the upper surface 4. The nickel layer 15 has a thickness of 0.5 μm to 3 μm, for example. In order to enhance the arc extinguishing function of the fuse element, an arc extinguishing material layer 17 made of silicon resin is formed between the upper surface 4 and the nickel layer 15 in the center of the upper surface 4. A copper layer 16 is deposited as a fuse element over the entire upper surface of the nickel layer 15. The copper layer 16 has a thickness of 2 μm to 20 μm, for example. The copper layer 16 is formed by electrolytic plating.

  A nickel layer 18 is deposited as a fuse element not in the entire upper surface of the copper layer 16 but in a region from the vicinity of the end face 8 to the vicinity of the end face 10. As shown in FIG. 2, the nickel layer 18 is formed up to the vicinity of the side surfaces 12 and 14 and covers both sides of the copper layer 16 and the nickel layer 15. The thickness of the nickel layer 18 on the copper layer 16 is, for example, 0.5 μm to 3 μm. Thus, the copper layer 16 is sandwiched between the nickel layers 15 and 18 on both the upper and lower sides. On the upper surface of the nickel layer 18, a low melting point metal layer, for example, a tin layer 20 is deposited for adjusting the residual resistance. As shown in FIG. 2, the width of the tin layer 20 is the same as that of the nickel layer 18 below the tin layer 20, but its length is shorter than that of the nickel layer 18 and is located on the center side of the nickel layer 18. ing. As described above, the fuse element includes the nickel layer 15, the copper layer 16, the nickel layer 18, and the tin layer 20.

  A silicon resin layer 22 is formed in contact with the entire area of the tin layer 20 and the nickel layer 18 so as to completely cover the portion excluding a part of the end faces 8 and 10 side.

  Silver-based resin layers 24 and 26 are formed on the end faces 8 and 10 of the insulating substrate 2 as electrode formation bases. These silver-based resin layers 24 and 26 extend to part of the upper surface 4 and the lower surface 6, and the side surface shape is substantially U-shaped. In particular, the upper surface 4 is deposited on the copper layer 16. Copper layers 28 and 30 are deposited on the outer surface sides of the silver-based resin layers 24 and 26 as part of the end face electrodes, and the copper layers 28 and 30 are formed on the upper surface of the insulating substrate 2. 26 extends beyond the outer surface of the copper layer 26 and partially beyond both ends of the nickel layer 18 (ends on the end surfaces 8 and 10 side), and is deposited on the upper surface of the copper layer 16 and the end portion of the nickel layer 15. Yes. The copper layers 28 and 30 are attached to the silver resin layers 24 and 26 so as to surround the silver resin layers 24 and 26 on the lower surface 6 side of the insulating substrate 2. As a result, the portions of the copper layer 16 and the nickel layer 15 (the portions on the end faces 8 and 10 side) on which the nickel layer 18 is not deposited and the portions of the copper layers 28 and 30 on the upper surface 4 of the insulating substrate 2 are the upper surfaces. Functions as an electrode. The copper layers 28 and 30 are formed by barrel plating.

  Nickel layers 32 and 34 are deposited as part of the end face electrodes on the outer surfaces of the copper layers 28 and 30, and tin layers 36 and 38 are deposited on the outer faces of the nickel layers 32 and 34 as part of the end faces. Has been.

  The nickel layers 32 and 34 and the tin layers 36 and 38 are on both ends of the nickel layer 18 on the upper surface 4 side of the insulating substrate 2, but are somewhat spaced from the silicon resin layer 22. is there. In order to fill these gaps, as the terminal boundary protection layer, a resin that does not transmit gas or moisture, for example, epoxy resin layers 40 and 42 are deposited on the nickel layer 18 and on the side surfaces thereof. The epoxy resin layers 40 and 42 function as a mask when the copper layers 28 and 30 are formed by barrel plating or when the nickel layers 32 and 34 and the tin layers 36 and 38 are formed. Prior to forming 30, it is formed on the nickel layer 18.

  In this chip-type fuse, a copper layer 16 that easily generates sulfide is used as a part of the fuse element. A nickel layer 18 is formed on a portion of the copper layer 16 that is not covered by the end face electrode. ing. As a result, even if this chip-type fuse is used in a sulfurized atmosphere, the nickel layer 18 prevents the sulfide factor from penetrating into the copper layer 16. Therefore, even when the silicon resin layer 22 that easily transmits gas and moisture is used as the protective layer, the sulfide factor does not easily reach the copper layer 16 and copper sulfide is not easily formed. Life can be extended. In addition, since the silicon resin layer 22 is used as the protective layer, arc discharge at the time of blown fuse can be suppressed by the arc extinguishing function, and further, the heat resistance increases, so that the residual resistance after fusing is sufficiently high. Fuse performance can be obtained, and the shock-absorbing action during fuse operation can be strengthened. Further, since the nickel layer 15 is also formed between the upper surface of the insulating substrate 2 and the copper layer 16, the sulfide factor hardly penetrates into the copper layer 16 from the insulating substrate 2 side, and it is difficult to form copper sulfide.

  The end face electrodes also use the copper layers 28 and 30. However, since the outer surfaces of the copper layers 28 and 30 are covered with the nickel layers 32 and 34, even if this chip-type fuse is exposed to a sulfur atmosphere. Copper sulfide is hardly formed from the copper layers 28 and 30 of the end face electrodes. Further, since the epoxy resin layers 40 and 42 are deposited on the nickel layer 18 between the ends of the both end surface electrodes on the upper surface 4 side of the insulating substrate 2 and the both ends of the silicon resin 22, from these portions. It is possible to prevent the sulfide factor from penetrating, and the copper layer 16 can more easily form copper sulfide. Note that since the regions where the epoxy resin layers 40 and 42 are deposited are only a part of both ends of the nickel layer 18, the use of the epoxy resins 40 and 42 having poor heat resistance does not affect the fuse performance. .

  The reason why the tin layer 20 is provided on the nickel layer 18 is as follows. In general, in a fuse, the fuse element is melted by heat generation due to an abnormal current, and the fuse element is aggregated in both electrodes at both ends of the fuse element to cut off electricity. For this reason, if the agglomeration of the two electrodes is insufficient, the residual resistance after fusing of the fuse element becomes low, and reconduction may occur. When the nickel layer 18 is used as a part of the fuse element as in the present embodiment, the melting point of nickel is higher than that of the conventional fuse element. Therefore, if heat generation due to an abnormal current is insufficient, aggregation is unlikely to occur. . Therefore, by forming a tin layer 20 using tin, which is an example of a low melting point metal, on a part of the nickel layer 18, an alloy of a low melting point metal containing nickel is formed at temperatures before and after the fusing of the fuse element. The residual resistance is high. Of course, the tin layer 20 also prevents the sulfide factor from penetrating into the copper layer 16. Instead of tin, an indium, bismuth or lead layer can be formed as a low melting point metal layer.

  In the above embodiment, the copper layer 16 is used as a part of the fuse element. However, instead of this, a silver layer can be used, or an alloy of copper and other metals, for example, an alloy of copper and tin, silver And other metals such as alloys of silver and tin can also be used. In the above embodiment, the nickel layer 15 and the copper layer 16 are provided over the entire area of the upper surface 4 of the insulating substrate 2; In addition, although the nickel layer 15 is provided, the nickel layer 15 can be omitted when it is difficult for the sulfide factor from penetrating the copper layer 16 from the insulating substrate 2 side. Further, although the arc extinguishing material layer 17 is formed at a part between the upper surface 4 and the nickel layer 15, the arc extinguishing material layer 17 may be provided between the upper surface 4 and the fuse element layer 16.

2 Insulating substrate 16 Copper layer 18 Nickel layer 22 Silicon resin layer

Claims (5)

An insulating substrate;
A fuse layer formed on one surface of the insulating substrate, having a copper layer, and a nickel layer covering the copper layer in contact with the copper layer;
A silicon resin layer covering the fuse layer in contact with the fuse layer;
Chip-type fuse provided.   2. The chip type fuse according to claim 1, wherein a low melting point metal layer is formed on a part of the nickel layer of the fuse layer.   2. The chip type fuse layer according to claim 1, wherein another nickel layer is interposed between the metal layer and the one surface of the insulating substrate.   4. The chip type fuse according to claim 3, wherein an electrode having another copper layer electrically connected to the copper layer is formed, and the copper layer of the electrode is covered with another nickel layer.   2. The chip-type fuse according to claim 1, wherein an electrode having another copper layer electrically connected to the copper layer is formed, and the copper layer of the electrode is also covered with another nickel layer, A chip-type fuse in which an epoxy resin layer is formed between a nickel layer and the other nickel layer.

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