Chip-type fuse

Abstract

Chip-type fuse, comprehensive: a plate-shaped melting body (26) comprising inner electrodes (28, 30) arranged appropriately near both ends of a straight line, and a meltable area (32) arranged between the inner electrodes (28, 30), wherein the meltable area (32) is integrated with the inner electrodes (28, 30) and is narrower than the inner electrodes (28, 30); a housing (2) in which the melting body (26) is housed, wherein exposed areas of the inner electrodes (28, 30), which are located near the two ends of the straight line respectively, are exposed from the housing (2), and conductive layers (50, 52) formed in such a way as to cover the exposed areas of the inner electrodes (28, 30) in the housing (2), wherein projections (38, 40) each extend outwards from the exposed areas and are integrated with the exposed areas and are covered with the conductive layers (50, 52), wherein the housing (2) has concave areas (19, 21) which contain concave surfaces (16, 18), wherein the concave surfaces (16, 18) are arranged near the two ends of the straight line and parts of the concave surfaces (16, 18) touch the straight line, wherein the conductive layers (50, 52) are formed on the concave surfaces and the projections extend from the concave surfaces (16, 18) into the concave areas (19, 21), characterized in that the inner electrodes (28, 30) have recessed surfaces (34, 36), wherein each of the recessed surfaces (34, 36) is arranged at least partially in the concave area (19, 21) and each of the projections (38,40) is located between the recessed area (34,36) and the concave area (16,18).

Description

Technical field

[0001] The present invention relates to a chip-type fuse and in particular to its electrodes. Background of the invention

[0002] An example of a conventional chip-type fuse is disclosed in international patent publication WO 93 / 17442 A1. The chip-type fuse comprises an arrangement with a substrate made from a cuboid glass plate. A thin-film metallic fuse element is formed on one top surface of the substrate. The fuse element has rectangular electrodes at the ends of the substrate's top surface. A fuse link, narrower than the electrodes, is formed between the electrodes. The fuse element is covered with a silicon dioxide passivation layer. A cuboid glass cover is bonded to the passivation layer by an epoxy layer. The electrodes are exposed at both end faces of the substrate and the cuboid glass cover.Plating layers, such as nickel and chromium, cover both end faces of the substrate and the cuboid glass cover, with the edges of the underside following the end faces of the substrate and the edges of the top side of the cover following the end faces of the cuboid glass cover. Solder layers cover the plating layers. The plating layers bond the solder layers and the locking element.

[0003] Document US 2015 / 0002258A1 discloses a terminal-integrated fuse comprising two planar elements that serve as terminals for mounting on a substrate. The two planar elements are spaced apart on the same horizontal plane. A fuse body is located on a horizontal plane at a height different from the plane of said horizontal plane and between the planar elements. The fuse body is integrally formed with the planar elements. A housing has side walls and end walls arranged around an opening. The fuse body is located within the housing. The two planar elements are each in contact with the end walls. An area of ​​arc-suppressing material is provided within the housing such that the fuse body is embedded therein. Summary of the invention

[0004] In the aforementioned chip-type fuse, the electrodes integrated with the fuse connection are exposed at both end faces of the substrate and the cuboid glass cover, and are only in contact with the coating layers at these two end faces. Therefore, a sufficient electrical connection between the coating layers and the electrodes is not achieved.

[0005] One object of the present invention is to provide a chip-type fuse in which a sufficient electrical connection is obtained between the coating layers and the electrodes formed in the chip-type fuse.

[0006] A chip-type fuse according to one aspect of the present invention comprises a plate-shaped fuse body. Inner electrodes are arranged along both edges of a straight line within the fuse body. The inner electrodes can have any shape. A meltable area is formed between the inner electrodes. The meltable area is integrated with the inner electrodes and is narrower than the inner electrodes. The meltable area can have one of several shapes, such as a linear shape or a curved shape. The fuse body is arranged in a housing. The housing can have one of several shapes in which the fuse body can be arranged. In a case where the chip-type fuse is a surface-mount fuse, it is desirable that at least one surface of the housing be flat.The areas of the inner electrodes located at both ends of the straight line are exposed from the housing. These areas (which may be referred to as exposed areas) are each covered with conductive layers. The conductive layers can be formed by plating the exposed areas or by applying conductive coating materials to them. The conductive layers may also extend to surfaces other than the exposed area within the housing. Any projections extending outwards from the exposed areas are integrally formed with the exposed areas and are covered with conductive layers.

[0007] In this arrangement, the protrusions in the plate-shaped melt body extend from the inner electrodes, which are integrally formed with the meltable area, and the protrusions are each covered with the conductive layers. This ensures sufficient electrical connections between each of the inner electrodes and each of the conductive layers. When the inner electrodes and the meltable area are formed using coating techniques, it is difficult to create the protrusions extending from the inner electrodes.

[0008] According to the invention, the inner electrodes have concave regions containing concave surfaces near both ends of the straight line, with portions of the concave surfaces touching the straight line. In this case, the conductive layers are formed on the concave surfaces, and the projections extend from the concave surfaces into the concave regions.

[0009] In this arrangement, the protrusions do not protrude from the concave areas. Therefore, when soldering the chip-type fuse to a printed circuit board, the protrusions do not interfere with the soldering process.

[0010] Furthermore, the inner electrodes have recessed surfaces, with at least parts of the recessed surface being located in the concave areas of the housing. In this case, the protrusions are situated between the recessed surfaces and the concave surfaces.

[0011] This arrangement makes it possible to simultaneously form concave surfaces in the fuse body and areas that become protrusions when the fuse body is inserted into the housing. Therefore, the manufacturing of this chip-type fuse is simplified.

[0012] Furthermore, the projections can extend from the entire surface of the concave areas, as viewed from above, into the concave regions. This arrangement allows the surface area of ​​the projections to be increased. As a result, more reliable electrical connections are achieved between the conductive layers and the inner electrodes.

[0013] In terms of chip-type fuses, the housing can have at least one flat surface. In this case, the conductive layers are extended accordingly to the flat surface. This arrangement makes the chip-type fuse suitable for surface mounting.

[0014] In terms of chip-type protection, the package can have first and second surfaces that are identical in shape and spaced parallel to each other. In this case, the package has a circumferential surface that surrounds the perimeter of the first and second surfaces, and the protrusions extend from this circumferential surface. The package can, for example, have the shape of a rectangular parallelepiped, a disk, an elliptical shape, or a shell.

[0015] Furthermore, the casing may have concave surfaces near both ends of the straight line, which are partially in contact with the straight line and intersect with the first and second surfaces. In this case, the projections extend from the entire surface of the concave surfaces when viewed from above, and the coating layers are formed accordingly over the entire surface of the concave surfaces.

[0016] With this arrangement, when the chip-type fuse is used for surface mounting, electrical connections between the conductive layers and the inner electrodes are very well established. Brief description of the drawings Fig. Figure 1 shows a longitudinal section front view of a chip-type fuse according to a first embodiment of the present invention. Fig. Figure 2 shows a top view of a terminal-integrated chip-type fuse. Fig. 1. Fig. Figure 3 shows a left side view of the chip-type fuse. Fig. 1. Fig. Figure 4 shows a top view of the lower housing part of the chip-type fuse. Fig. 1. Fig. Figure 5 shows a top view of the melting body of the chip-type fuse. Fig. 1. Fig. Figure 6 shows a top view of the cross-section of the chip-type fuse. Fig. 1. Fig. Figure 7 shows a top view of the semi-finished product of the chip-type fuse. Fig. 1. Fig. Figure 8 shows a longitudinal section view of a chip-type fuse according to the second embodiment of the present invention. Fig. Figure 9 shows a top view of the chip-type fuse of Fig. 8. Fig. Figure 10 shows a cross-sectional view of the chip-type fuse of Fig. 8. Fig. Figure 11a shows a modification of a melting body used in the chip-type fuse of the first embodiment. Fig. Figure 11b shows the other modification of the melting body used in the chip-type fuse of the first embodiment. Description of embodiments

[0017] A chip-type fuse according to a first embodiment of the present invention comprises a housing 2, as shown in the Fig. 1, Fig. 2 to Fig. Figure 3 shows, for example, that the housing 2 is formed in a generally rectangular parallelepiped shape and is made of glass epoxy. The housing 2 has a first surface, for example, a top surface 4, and a second surface, for example, a bottom surface 6. The top surface 4 and the bottom surface 6 contain the same shapes, e.g., rectangular faces arranged parallel to each other so that they are spaced apart and overlap each other. The housing 2 has a circumferential surface that surrounds the perimeter of the first and second surfaces. The circumferential surface includes, for example, side surfaces 8 and 10, and end surfaces 12 and 14, formed between the top surface 4 and the bottom surface 6. Each of these is rectangular. Concave surfaces 16 and 18 are formed accordingly in the end surfaces 12 and 14, respectively. The concave surfaces 16 and 18 are each positioned close to the center of the end surfaces 12 and 14, respectively.The concave surfaces 16 and 18 are formed inwards in the housing 2. In particular, the concave surfaces 16 and 18 are formed, for example, in arc shapes, especially semicircular shapes, by removing portions from the center and near the center of the end surfaces 12 and 14. The formation of the concave surfaces 16 and 18 creates semi-cylindrical, concave regions 19 and 21 on the end surfaces 12 and 14, respectively. The concave region 19 opens in the directions of the top surface 4, the bottom surface 6, and the end surface 12, and the concave region 21 also opens in the directions of the top surface 2, the bottom surface 6, and the end surface 14. As in . Fig. As shown in Figure 1, the housing 2 is divided at the midpoint of the connecting line linking the top 4 and the bottom 6 into an upper housing element 20 and a lower housing element 22, and both elements have the same shape. A cavity 24 is formed in the central region of the inside of the housing 2. The cavity 24 is shown in the top view of Fig. 4 a slotted hole.

[0018] As in Fig. As shown in Figure 1, a fused body 26 is arranged at a connection surface between the upper housing part 20 and the lower housing part 22. The fused body 26 contains internal electrodes 28 and 30 and a meltable area 32, as shown in Figure 1. Fig. 5 is shown. As in Fig. As shown in Figure 6, the inner electrodes 28 and 30 extend within the melt body 26 from both ends of a single straight line toward the center of the housing 2. This straight line is located, for example, at the midpoint of the end faces 12 and 14 and has a length equal to the distance between these end faces. The inner electrodes 28 and 30 are formed in a substantially rectangular shape, with a maximum width equal to the distance between the side faces 8 and 10 of the housing 2. The fusible area 32 is arranged along the straight line between the inner edges of the inner electrodes 28 and 30. The fusible area 32 is formed into a straight line with a narrower width than that of the inner electrodes 28 and 30 and is located within the cavity 24.The melting body 26 is a thin metal plate, for example a copper plate, formed by pressing or etching. The fusible part 32 with the internal electrodes 28 and 30 is integrated into the melting body 26.

[0019] As in Fig. As shown in Figure 5, recessed surfaces 34 and 36 are formed at the outer edges of the inner electrodes 28 and 30. The recessed surfaces 34 and 36 have, for example, arc shapes, in particular semicircular shapes, and are recessed in the direction of the central side of the fusible area 32. As shown in Fig. As shown in Figure 6, the melt body 26 is arranged on the lower housing part 22 such that the end faces 12 and 14 on the lower housing part 22 and the outer edges of the inner electrodes 28 and 30 coincide. In this arrangement, the centers of the recessed surfaces 34 and 36 lie on the straight line. The concave surfaces 16 and 18 and the recessed surfaces 34 and 36 are each arranged concentrically with respect to each other. The radii of the recessed surfaces 34 and 36 are smaller than the radii of the concave surfaces 16 and 18. As a result, the recessed surfaces 34 and 36 each project outwards from the concave surfaces 16 and 18. The areas that extend from the recessed surfaces 34 and 36 to the concave surfaces 16 and 18 are designated as projections 38 and 40. As shown in Figure 6, the recessed surfaces 34 and 36 project outwards from the concave surfaces 16 and 18. Fig. As shown in Figure 5, the projections 38 and 40 extend horizontally from the entire edges of the recessed surfaces 34 and 36, as viewed from their planes, into the concave regions 19 and 21. If the projections 38 and 40 are not present, the edges of the inner electrodes 28 and 30 on the concave surfaces 16 and 18 are exposed in the concave regions 19 and 21.

[0020] In this chip-type fuse, the upper housing element 20, the lower housing element 22, and the melting body 26 are prepared first. As in Fig. As shown in Figure 6, the melting element 26 is located on the lower housing part 22. As in Fig. As shown in Figure 7, the lower housing part 22 is covered with the upper housing part 20. The upper housing element 20 and the lower housing element 22 are glued together.

[0021] As in Fig. As shown in Figure 1, conductive layers, e.g., outer electrodes 42 and 44, are formed at one end of the top surface 4 and the bottom surface 6 of the housing 2, respectively. The outer electrodes 42 and 44 extend from the end face 12 of the housing 2 to a position beyond the concave surface 16 of the housing 2, have holes at positions corresponding to the concave surface 16, and have a width corresponding to the length from the side surface 8 to the side surface 10 of the housing 2. Similarly, conductive layers, e.g., outer electrodes 46 and 48, are also formed at the other ends of the top surface 4 and the bottom surface 6 of the housing 2, respectively. The outer electrodes 42, 44, 46, and 48 are, for example, made of a copper layer.

[0022] A conductive layer, e.g., a coating layer 50, is formed over the entire concave surface 16, such that the entire projection 38 is contained within the coating layer 50. A conductive layer, e.g., a coating layer 52, is also formed over the entire concave surface 18, such that the entire projection 40 is contained within the coating layer 52. The coating layers 50 and 52 extend to the top 4 and bottom 6 of the housing 2. The coating layer 50 covers the entire surfaces of the outer electrodes 42 and 44. The coating layer 52 covers the entire surfaces of the outer electrodes 46 and 48. Fig. 1, Fig. 2 to Fig. Figure 3 shows the coating layers 50 and 52 as a single layer for the sake of simplicity; however, they are actually composed of a multitude of coating layers, such as an electrolytic copper coating layer, an electrolytic nickel coating layer, and an electrolytic tin coating layer.

[0023] In this chip-type fuse, the projections 38 and 40 extend from the inner electrodes 28 and 30 across the concave surfaces 16 and 18 into the concave areas 19 and 21, and the entire surfaces of the projections 38 and 40 are each covered with the coating layers 50 and 52, respectively. Therefore, the contact area between the projection 38 and the coating layer 50 is large, ensuring good electrical contact, and the contact area between the projection 40 and the coating layer 52 is also large, ensuring good electrical contact. In particular, in this embodiment, since the projections 38 and 40 each protrude from the entire edges of the concave surfaces 16 and 18, so that the areas of the projections 38 and 40 are large, the contact area between the projection 38 and the coating layer 50 and the contact area between the projection 40 and the coating layer 52 are further increased.As a result, reliably good electrical connections are established between the projection 38 and the coating layer 50, and between the projection 40 and the coating layer 52. The projections 38 and 40 are positioned within the concave areas 19 and 21, respectively, and do not protrude outwards from these areas. Therefore, the projections 38 and 40 do not impede the soldering of the chip-type fuse to the circuit board.

[0024] The Fig. 8, Fig. 9 to Fig. Figure 10 shows the chip-type fuse of the second embodiment according to the present invention. In the chip-type fuse of this embodiment, the corresponding concave areas 19 and 21 and their surrounding areas in a housing 2a, as in the chip-type fuse of the first embodiment, are removed, so that the length of the housing 2a is shortened by the amount removed. Along with the removal, the inner electrodes 28a and 30a are also shortened so that their outer edges coincide with the end faces 12a and 14a of the housing 2a, as shown in Figure 10. Fig. Figure 10 shows that the projections 38a and 40a extend horizontally and outwards from the entire outer edge of the inner electrodes 12a and 14a. When the projections 38a and 40a are absent, the inner electrodes 28a and 30a are exposed at the end faces 12a and 14a. The entire surfaces of the projections 38a and 40a are covered with the coating layers 50a and 52a. Since the other configurations are the same as those of the chip-type fuse of the first embodiment, the same reference numerals are used for the corresponding parts, and their descriptions are omitted. Correspondingly good electrical connections are reliably established between the projection 38a and the coating layer 50a and between the projection 40a and the coating layer 52a.

[0025] The chip-type fuses of the two embodiments above can be modified in various ways. For example, in the chip-type fuse of the first embodiment, the length of the meltable area 32 can be changed according to the desired melting properties of the chip-type fuse. For example, as shown in Fig. As shown in Figure 11a, a meltable area 32b with a shorter length than that of the meltable area 32 can be used; a meltable area can be curved instead of linear as in the meltable area 32 of the chip-type fuse of the first embodiment; and a characteristic setting section can be provided in the middle of the meltable area 32. Similarly, in the chip-type fuse of the second embodiment, the meltable area 32 can be modified.

[0026] In the chip-type fuses of the two above embodiments, arc-suppressing materials can be attached to the meltable areas 32 and 32a respectively, and arc-suppressing materials can also be cast into the cavity 24 to enclose the meltable areas 32 and 32a respectively.

[0027] It is possible that, as in Fig.As shown in Figure 11b, the widths of the inner electrodes 28b and 30b are narrower than those of the inner electrodes 28 and 30 of the first embodiment, in order to form spaces accordingly in the sides of the side surfaces 8 and 10 of the housing 2, and reinforcement patterns 62 and 64 are each provided independently of the inner electrodes 28b and 30b at the corresponding intervals. The provision of the reinforcement patterns 62 and 64 increases the strength of the housing 2. The reinforcement patterns 62 and 64 can be formed from the metal by pressing or etching the metal at the same time as the melt body 26 is formed. Reinforcement patterns can be provided similarly in the chip-type fuse of the second embodiment.

[0028] In the chip-type fuses of the two embodiments described above, the coating layers 50, 52, 50a and 52a are used as the conductive layers, but conductive paint layers can be used instead of the coating layers 50, 52, 50a and 52a. In particular, in the chip-type fuse of the first embodiment, the conductive paint layers can each be provided accordingly over the entire areas of the concave regions 19 and 21.

[0029] In the chip-type fuses of the two above embodiments, the housings 2 and 2a have a rectangular parallelepiped shape, but they can have other shapes, e.g. disk shapes, elliptical plate shapes or shell shapes.

[0030] In the chip-type fuses of the two embodiments described above, the outer electrodes 42 and 46 are located on the upper surfaces of the housings 2 and 2a, and the outer electrodes 44 and 48 are located on their lower surfaces, although only the outer electrodes 44 and 48 may be located on the lower surfaces. In these cases, the coating layer 50 may be configured to cover the projection 38 and the outer electrode 44, and the coating layer 52 may be configured to cover the projection 40 and the outer electrode 48. Similarly, the coating layer 50a may be configured to cover the projection 38a and the outer electrode 44, and the coating layer 52a may be configured to cover the projection 40a and the outer electrode 48.

[0031] In the chip-type fuse of the first embodiment, the concave surfaces 16 and 18 and the concave surfaces 34 and 36 have semicircular shapes, but the shapes are not limited to such shapes; they can be, for example, U-shapes, channel shapes, or V-shapes.

[0032] In the first embodiment of the chip-type fuse, the projections 38 and 40 each project from the entire surface of the concave surfaces 16 and 18, but the projections 38 and 40 may also each project from portions of the concave surfaces 16 and 18. Similarly, in the second embodiment, the projections 38a and 40a each project from the entire outer edges of the inner electrodes 28a and 30a, but may also project from only portions thereof. In the chip-type fuses of the two embodiments above, the entire areas of the projections 38, 40, 38a, and 40a project horizontally, but, for example, the tips of the projections 38, 40, 38a, and 40a may be curved toward the top 4 or the bottom 6 of the housings 2 and 2a. In these cases, the coating layers 50, 50a, 52 and 52a are designed to cover the curved areas.

Claims

[1] Chip-type fuse, comprising: a plate-shaped melting body (26) comprising inner electrodes (28, 30) arranged appropriately near both ends of a straight line, and a fusible area (32) arranged between the inner electrodes (28, 30), wherein the fusible area (32) is integrated with the inner electrodes (28, 30) and is narrower than the inner electrodes (28, 30); a housing (2) in which the melting body (26) is housed, wherein exposed areas of the inner electrodes (28, 30), which are located near the two ends of the straight line respectively, are exposed from the housing (2), and conductive layers (50, 52) formed in such a way as to cover the exposed areas of the inner electrodes (28, 30) in the housing (2), wherein projections (38, 40) each extend outwards from the exposed areas and are integrated with the exposed areas and are covered with the conductive layers (50, 52), wherein the housing (2) has concave areas (19, 21) which contain concave surfaces (16, 18), wherein the concave surfaces (16, 18) are arranged near the two ends of the straight line and parts of the concave surfaces (16, 18) touch the straight line, wherein the conductive layers (50, 52) are formed on the concave surfaces and the projections extend from the concave surfaces (16, 18) into the concave areas (19, 21), characterized by , that the inner electrodes (28,30) have recessed surfaces (34,36), each of the recessed surfaces (34,36) being arranged at least partially in the concave area (19,21) and each of the projections (38,40) being located between the recessed surface (34,36) and the concave surface (16,18). [2] Chip-type fuse according to claim 1, wherein the projections (38, 40) extend from the total areas of the concave surfaces (16, 18) in the direction of the concave regions (19, 21). [3] Chip-type fuse according to claim 1, wherein the housing (2) has at least one flat surface (4,6) wherein the conductive layers (50,52) extend on this flat surface (4,6). [4] Chip-type fuse according to claim 1, wherein the housing has first and second surfaces (4, 6) which have the same shape and are spaced parallel to each other, and a circumferential surface (8, 10, 12, 14) which surrounds the perimeter of the first and second surfaces (4, 6), wherein the projections (38, 40) protrude from the circumferential surface (8, 10, 12, 14). [5] Chip-type fuse according to claim 4, wherein the housing (2) has concave surfaces (16, 18) that partially touch the two ends of the straight line and intersect with the first and second surfaces (4, 6), and wherein the projections (38, 40) each extend from the totality of the concave surfaces (16, 18) accordingly and the conductive layers (50, 52) are each formed accordingly over the entire area of ​​the concave surfaces (16, 18).

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