TW201707036A - Fuse element and fuse device - Google Patents

Abstract

To provide a fuse element and a fuse device, capable of preventing occurrence of trouble such as a shifting of a fused spot from a design position or rising of a conductor resistance of a part eliminated a low melting metal even when the low melting metal is fused at a temperature at a reflow mounting time. According to a fuse element, and a fuse device using the fuse element, in the fuse element comprising an electric conductive path of the fuse device, and fused by a self-heating by conducting a current exceeding a rating, the fuse element includes a low melting point metal layer and a high melting point metal layer laminated to the low melting point metal layer, and uses the action that the low melting point metal layer corrodes and fuses the high melting point metal layer. One of or both the low melting point metal layer and the high melting point metal layer includes a high film thickness part and a low film thickness part having a different thickness.

Description

Fuse unit and fuse element

The present invention relates to a fuse unit and a fuse element that is mounted on a conductive path and that is blown off due to self-heating when a rated abnormal current (overcurrent) is passed to block the conductive path.

Conventionally, a fuse unit has been used in order to protect a circuit component disposed on the conductive path when an overcurrent passes over the conductive path. As such a fuse unit, Pb (lead)-containing solder is preferably used. However, under the RoHS Directive (Restriction of Hazardous Substances Directive), the use of lead-containing solders is limited, and it is expected that the requirements for lead-free will become stricter in the future.

In this case, for example, Patent Document 1 discloses a Pb-free fuse unit in which a high-melting-point metal layer is laminated on a surface of a low-melting-point metal layer, and when an overcurrent causes heat generation, a low-melting-point metal The layer erodes the high melting point metal layer while melting, and can be rapidly melted by a temperature lower than the melting point of the high melting point metal.

[Previous Technical Literature]

(Patent Literature)

Patent Document 1: Japanese Laid-Open Patent Publication No. 2014-209467

When a fuse unit in which a high melting point metal layer is laminated on the surface of a low melting point metal layer is reflowed and mounted on a circuit board, even if the low melting point metal is melted at the reflow temperature, the laminated high melting point metal It does not melt, so it has the advantage of maintaining the shape of the unit.

However, under actual reflow conditions, the molten low melting point metal will flow unevenly in the high melting point metal (aggregate at several places) and also cause a change in the shape of the unit. When such a thing occurs, there is a fear that a positional shift from the design of the fuse is caused, or a conductor having a portion where the low-melting metal is lost is increased.

The present invention has been made in view of the above problems, and an object thereof is to provide a fuse unit and a fuse element which can suppress a self-design of a fuse even if a low melting point metal is melted at a temperature at the time of reflow assembly. The positional shift or the occurrence of a defective state in which the conductor resistance of the portion where the low melting point metal is lost is suppressed.

In order to solve the above problems, in the fuse unit of the present invention, the conductive path constituting the fuse element is blown due to self-heating due to passage of a rated current, and has a low melting point metal layer and is laminated on the low melting point metal layer. a high melting point metal layer, wherein the low melting point metal layer functions to erode and melt the high melting point metal layer, the fuse unit is characterized by: the low melting point metal layer and the high melting Either or both of the point metal layers have a high film thickness portion and a low film thickness portion having different thicknesses.

Further, in the fuse unit according to another aspect of the present invention, the conductive path constituting the fuse element is blown by self-heating due to passage of a rated current, and has a low-melting-point metal layer and a laminated layer on the low-melting-point metal layer. a high melting point metal layer, wherein the low melting point metal layer functions to erode and melt the high melting point metal layer, the fuse unit characterized in that the low melting point metal layer has a mountain portion in the thickness direction and Valley-shaped department.

Further, the fuse element according to the present invention includes: an insulating substrate; and a fuse unit that is mounted on the insulating substrate and that is blown by self-heating due to passage of a rated current; and the fuse unit has a low melting point metal layer and a high melting point metal layer laminated on the low melting point metal layer, wherein the low melting point metal layer functions to erode and melt the high melting point metal layer, and the fuse element is characterized by: Either or both of the low-melting-point metal layer and the high-melting-point metal layer have a high film thickness portion and a low film thickness portion having different thicknesses.

According to the present invention, it is possible to provide a fuse unit and a fuse element which can suppress the displacement of the fuse from the design due to the restriction of the movement of the molten low-melting metal layer at the temperature at the time of the reflow assembly. Or suppressing the occurrence of a defective state in which the conductor resistance of the portion of the low melting point metal is increased.

10‧‧‧Fuse unit

10'‧‧‧Fuse unit

11‧‧‧Low-melting metal layer

11a‧‧‧High film thickness

11b‧‧‧Low film thickness

11c‧‧‧ Yamagata

11d‧‧‧Valley

12‧‧‧High melting point metal layer

12a‧‧‧High film thickness

12b‧‧‧low film thickness

13‧‧‧Oxidation preventive film

14‧‧‧Protection components

15‧‧‧ cover

16‧‧‧ frame

17‧‧‧Protection shell

20‧‧‧Fuse unit

30‧‧‧Fuse unit

40‧‧‧Fuse unit

50‧‧‧Fuse unit

60‧‧‧Fuse unit

70‧‧‧Fuse unit

100‧‧‧Fuse components

101‧‧‧Insert substrate

101a‧‧‧ Surface of insulating substrate

101b‧‧‧Back of the insulating substrate

102‧‧‧First electrode

103‧‧‧second electrode

104‧‧‧Protective layer

105‧‧‧bonding material

106‧‧‧flux

107‧‧‧cover body components

108‧‧‧Clamping terminal

110‧‧‧Fuse components

111‧‧‧Insulated terminal block

112‧‧‧First wire terminal

113‧‧‧Second wire terminal

114‧‧‧ bolt

115‧‧‧ nuts

200‧‧‧Fuse unit

300‧‧‧Fuse unit

Fig. 1(a) is a schematic cross-sectional view showing a cross-sectional shape of a fuse unit 10 to which the present invention is applied.

The first (b) is a perspective view of the fuse unit 10.

Fig. 1(c) is a schematic cross-sectional view showing the cross-sectional shape of the fuse unit 20 to which the present invention is applied.

The first (d) diagram is a perspective view of the fuse unit 20.

Fig. 2(a) is a schematic cross-sectional view showing the cross-sectional shape of the fuse unit 30 to which the present invention is applied.

The second (b) is a perspective view of the fuse unit 30.

Fig. 2(c) is a schematic cross-sectional view showing the cross-sectional shape of the fuse unit 40 to which the present invention is applied.

The second (d) diagram is a perspective view of the fuse unit 40.

Fig. 3(a) is a schematic cross-sectional view showing the cross-sectional shape of the fuse unit 50 to which the present invention is applied.

The third (b) is a perspective view of the fuse unit 50.

Fig. 3(c) is a schematic cross-sectional view showing the cross-sectional shape of the fuse unit 60 to which the present invention is applied.

The third (d) diagram is a perspective view of the fuse unit 60.

Fig. 4(a) is a schematic cross-sectional view showing the cross-sectional shape of the fuse unit 70 to which the present invention is applied.

The fourth drawing (b) is a perspective view of the fuse unit 70.

Fig. 5 is a schematic view showing an application example of a fuse unit to which the present invention is applied.

Fig. 6 is a schematic view showing an application example of a fuse unit to which the present invention is applied.

Fig. 7 is a schematic view showing an application example of a fuse unit to which the present invention is applied.

Fig. 8 is a schematic view showing an application example of a fuse unit to which the present invention is applied.

Fig. 9 is a schematic cross-sectional view showing a cross-sectional shape of a fuse element 100 to which the present invention is applied.

Fig. 10 is a schematic cross-sectional view showing a cross-sectional shape of a fuse element 110 to which the present invention is applied.

Fig. 11 is a schematic cross-sectional view showing an example in which a fuse unit to which the present invention is applied is used as a fuse element.

Fig. 12 is a view for explaining the test of the effect of suppressing the movement of the low-melting-point metal at the temperature at the time of the reflow assembly.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the present invention is not limited to the following description, and may be appropriately modified without departing from the scope of the invention. Moreover, the drawings are only schematic views, and the ratios of various sizes and the like may be different from actual objects. The specific dimensions and the like should be judged by considering the following instructions. Moreover, the drawings also naturally include portions having different dimensional relationships or ratios from each other.

A fuse unit according to one aspect of the present invention has a low melting point metal layer and a high melting point metal layer laminated on the low melting point metal layer, wherein the molten low melting point metal serves to erode and melt the high melting point metal layer For example, either or both of the low-melting-point metal layer and the high-melting-point metal layer of the fuse unit have a high film thickness portion and a low film thickness portion having different thicknesses, thereby limiting melting at a temperature at the reflow assembly. The movement of the low melting metal layer.

[fuse unit]

Fig. 1(a) is a schematic cross-sectional view showing a cross-sectional shape of a fuse unit 10 to which the present invention is applied. The first (b) is a perspective view of the fuse unit 10. The fuse unit 10 is a laminated structure composed of an inner layer and an outer layer, and has a low melting point metal layer 11 as an inner layer and a high melting point metal layer 12 laminated on both sides of the low melting point metal layer 11 As an outer layer. In the fuse unit 10, the low-melting-point metal layer 11 includes a high-thickness portion 11a and a low-thickness portion 11b, and the low-thickness portion 11b is thinner than the thickness of the high-thickness portion 11a in the thickness direction.

As shown in Fig. 1(a) and Fig. 1(b), the low-melting-point metal layer 11 of the fuse unit 10 is formed on both sides in the thickness direction of the substantially thin-shaped low-thickness portion 11b in the cross-sectional shape. There is a high film thickness portion 11a formed into a substantially trapezoidal shape, and the low film thickness portion 11b and the high film thickness portion 11a are continuously formed in the longitudinal direction. Here, the high film thickness portion 11a is preferably configured to have a thickness twice or more with respect to the low film thickness portion 11b. Further, in the description of the present invention, the thickness direction indicates the vertical direction of the fuse unit on the paper surface of the first (a) drawing, and the longitudinal direction indicates the first (a). The left and right direction of the fuse unit on the same sheet of paper. Further, the high melting point metal layer 12 of the fuse unit 10 is laminated with a predetermined thickness corresponding to the outer shape of the low melting point metal layer 11.

Fig. 1(c) is a schematic cross-sectional view showing the cross-sectional shape of the fuse unit 20 to which the present invention is applied. The first (d) diagram is a perspective view of the fuse unit 20. Similarly to the fuse unit 10, the fuse unit 20 is a laminated structure composed of an inner layer and an outer layer, and has a low melting point metal layer 11 as an inner layer and a high melting point metal layer laminated on the low melting point metal layer 11. 12 comes as the outer layer. The fuse unit 20 has a low-melting-point metal layer 11 and an outer layer of a high-melting-point metal layer 12, each having a high-thickness portion 11a and a low-thickness portion 11b, and a high-thickness portion 12a and a low-thickness portion 12b. .

As shown in FIGS. 1(c) and 1(d), the fuse unit 20 has the low-melting-point metal layer 11 having the same shape as the fuse unit 10, and the fuse unit 20 of the high-melting-point metal layer 12 is laminated. The lamination of the high-melting-point metal layer 12 is performed in such a manner that the outer shape is a planar shape. In other words, the high melting point metal layer 12 of the fuse unit 20 has a high film thickness portion 12a in the thickness direction and a low melting point metal layer in a portion corresponding to the low film thickness portion 11b of the low melting point metal layer 11. A portion of the high-thickness portion 11a of the eleventh portion has a low-thickness portion 12b in the thickness direction, and the low-thickness portion 12b is thinner than the high-thickness portion 12a in thickness, and is laminated in this manner.

Fig. 2(a) is a schematic cross-sectional view showing the cross-sectional shape of the fuse unit 30 to which the present invention is applied. Figure 2(b) is a fuse unit 30 Stereogram. The fuse unit 30 is a laminated structure composed of an inner layer and an outer layer, and has a low-melting-point metal layer 11 as an inner layer and a high-melting-point metal layer 12 laminated on the low-melting-point metal layer 11 as an outer layer. In the fuse unit 30, the inner low-melting-point metal layer 11 includes a high-thickness portion 11a and a low-thickness portion 11b, and the low-thickness portion 11b is thinner than the high-thickness portion 11a in the thickness direction.

As shown in FIGS. 2(a) and 2(b), the low-melting-point metal layer 11 of the fuse unit 30 is formed on one side in the thickness direction of the approximately rectangular low-thickness portion 11b in the cross-sectional shape. The high film thickness portion 11a formed into a substantially trapezoidal shape is formed, and the low film thickness portion 11b and the high film thickness portion 11a are continuously formed in the longitudinal direction. Further, the high melting point metal layer 12 of the fuse unit 30 is laminated to have a predetermined thickness corresponding to the outer shape of the low melting point metal layer 11.

Fig. 2(c) is a schematic cross-sectional view showing the cross-sectional shape of the fuse unit 40 to which the present invention is applied. The second (d) diagram is a perspective view of the fuse unit 40. Similarly to the fuse unit 30, the fuse unit 40 is a laminated structure composed of an inner layer and an outer layer, and has a low melting point metal layer 11 as an inner layer and a high melting point metal layer laminated on the low melting point metal layer 11. 12 comes as the outer layer. The fuse unit 40 has a low-melting-point metal layer 11 and an outer layer of a high-melting-point metal layer 12, each having a high-thickness portion 11a and a low-thickness portion 11b, and a high-thickness portion 12a and a low-thickness portion 12b. .

As shown in FIGS. 2(c) and 2(d), the fuse unit 40 has a low-melting-point metal layer 11 having the same shape as the fuse unit 30, The layering of the high-melting-point metal layer 12 is performed such that the outer shape of the laminated fuse unit 40 of the high-melting-point metal layer 12 is planar. In other words, the high melting point metal layer 12 of the fuse unit 40 has a high film thickness portion 12a in the thickness direction at a portion corresponding to the low film thickness portion 11b of the low melting point metal layer 11, and corresponds to the low melting point metal layer. A portion of the high-thickness portion 11a of the eleventh portion has a low-thickness portion 12b in the thickness direction, and the low-thickness portion 12b is thinner than the high-thickness portion 12a in thickness, and is laminated in this manner.

Here, the fuse unit according to another aspect of the present invention includes a low melting point metal layer and a high melting point metal layer laminated on the low melting point metal layer, wherein the molten low melting point metal serves to erode and melt high The function of the melting point metal layer, the low melting point metal layer, has a ridge portion and a valley portion in the thickness direction, thereby restricting the movement of the molten low melting point metal layer at the temperature at the time of the reflow assembly.

Fig. 3(a) is a schematic cross-sectional view showing the cross-sectional shape of the fuse unit 50 to which the present invention is applied. The third (b) is a perspective view of the fuse unit 50. The fuse unit 50 is a laminated structure composed of an inner layer and an outer layer, and has a low melting point metal layer 11 as an inner layer and a high melting point metal layer 12 laminated on both sides of the low melting point metal layer 11 As an outer layer. The fuse unit 50 has a lower-melting-point metal layer 11 in its inner layer, and has a mountain portion 11c and a valley portion 11d in the thickness direction.

As shown in FIGS. 3(a) and 3(b), the low-melting-point metal layer 11 of the fuse unit 50 has a mountain portion 11c and a valley portion 11d in a cross-sectional shape, and the mountain portion 11c and the valley portion 11d is in the length direction Formed continuously. Further, the high-melting-point metal layer 12 of the fuse unit 50 is laminated to have a predetermined thickness corresponding to the outer shape of the low-melting-point metal layer 11 (the shape of the ridge portion 11c and the valley portion 11d).

Fig. 3(c) is a schematic cross-sectional view showing the cross-sectional shape of the fuse unit 60 to which the present invention is applied. The third (d) diagram is a perspective view of the fuse unit 60. Similarly to the fuse unit 50, the fuse unit 60 is a laminated structure composed of an inner layer and an outer layer, and has a low melting point metal layer 11 as an inner layer and a high melting point metal layer laminated on the low melting point metal layer 11. 12 comes as the outer layer. In the fuse unit 60, the inner low-melting-point metal layer 11 includes a chevron portion 11c and a valley portion 11d, and the outer high-melting-point metal layer 12 includes a high-thickness portion 12a and a low-thickness portion 12b.

As shown in FIGS. 3(c) and 3(d), the fuse unit 60 has the low-melting-point metal layer 11 having the same shape as the fuse unit 50, and the fuse unit 60 of the high-melting-point metal layer 12 is laminated. The lamination of the high-melting-point metal layer 12 is performed in such a manner that the outer shape is a planar shape. In other words, the high-melting-point metal layer 12 of the fuse unit 60 has a low-thickness portion 12b in the thickness direction at a portion corresponding to the chevron portion 11c of the low-thickness portion 11b of the low-melting-point metal layer 11, and corresponds to The portion of the valley portion 11d of the low-melting-point metal layer 11 has a high film thickness portion 12a in the thickness direction, and the high film thickness portion 12a is thicker than the low film thickness portion 12b, and is laminated in this manner.

Further, among the fuse units 10 to 60 and the like, the low-melting-point metal layer 11 of the inner layer includes the high-thickness portion 11a and the low-thickness portion 11b, and the low-thickness portion 11b is larger than the high-thickness portion 11a. Film on thickness The configuration of the thick and thinner is described. However, the configuration of the fuse unit may be such that only the outer layer of the high-melting-point metal layer 12 has the high-thickness portion 12a and the low-thickness portion 12b.

Fig. 4(a) is a schematic cross-sectional view showing a cross-sectional shape of the fuse unit 70 in which only the high-thickness portion 12a and the low-thickness portion 12b are provided in the high-melting-point metal layer 12. The fourth drawing (b) is a perspective view of the fuse unit 70. The fuse unit 70 is a laminated structure composed of an inner layer and an outer layer, and has a low-melting-point metal layer 11 as an inner layer and a high-melting-point metal layer 12 laminated on the low-melting-point metal layer 11 as an outer layer. The fuse unit 70 has an outer layer of a high-melting-point metal layer 12 having a high-thickness portion 12a and a low-thickness portion 12b. The low-thickness portion 12b is thinner than the high-thickness portion 12a in the thickness direction.

As shown in FIGS. 4(a) and 4(b), the low melting point metal layer 11 of the fuse unit 70 is formed into a substantially rectangular shape in a cross-sectional shape and laminated with a high melting point metal layer 12, the high melting point metal layer. 12 has a high film thickness portion 12a and a low film thickness portion 12b which are formed on both sides in the thickness direction of the surface of the low melting point metal layer 11 and have a substantially trapezoidal shape, and the low film thickness portion 12b is formed. The film thickness of the high film thickness portion 12a is thinner in the thickness direction.

Next, the low melting point metal layer 11 and the high melting point metal layer 12 constituting the fuse units 10 to 70 will be described. As the low-melting-point metal layer 11, for example, a so-called "Pb-free solder" metal material of Sn (tin) or a Sn-Cu (copper) alloy, a Sn-Bi (yttrium) alloy, or a Sn-Ag (silver) alloy can be used. . Furthermore, for these metal materials, rolling, pulling, and By annealing treatment or the like, a metal material (metal wire, metal foil, metal rolled plate) having a desired cross-sectional area can be obtained. The melting point of the low-melting-point metal layer 11 is not necessarily higher than the temperature of the reflow furnace, and may be melted at a temperature of 200 ° C to 240 ° C. Further, the high-melting-point metal layer 12 is a metal layer laminated on the surface of the low-melting-point metal layer 11, and for example, Ag, Cu, or an alloy containing Ag or Cu as a main component, and having a high melting point can be used. When the fuse units 10 to 70 are mounted on the insulating substrate by the reflow furnace, the high melting point metal layer 12 is not melted.

The fuse units 10 to 70 are laminated with a high-melting-point metal layer 12 as an outer layer on the low-melting-point metal layer 11 as an inner layer, whereby even when the temperature of the reflow furnace exceeds the melting temperature of the low-melting-point metal layer 11, The fuse units 10 to 70 are not blown. Therefore, the fuse units 10 to 70 can be efficiently assembled by reflow. Further, even if the temperature of the reflow furnace exceeds the melting temperature of the low-melting-point metal layer 11, the low-melting-point metal is melted, because either or both of the low-melting-point metal layer 11 and the high-melting-point metal layer 12 have a high film thickness having a different thickness. The portion and the low film thickness portion can suppress the movement of the low melting point metal.

Further, the fuse units 10 to 70 are not blown even if they are heated during the period in which the predetermined rated current passes. Furthermore, if a current having a higher value than the rated current passes, it will melt due to self-heating to block the conductive path between the electrodes. At this time, the fuse units 10 to 70 erode the high melting point metal layer 12 by the molten low melting point metal layer 11 so that the high melting point metal layer 12 is melted at a temperature lower than the melting temperature. Therefore, the fuse units 10 to 70 can utilize a low melting point metal layer The erosion of the high-melting-point metal layer 12 caused by 11 is blown in a short time. Further, as will be described later, when the molten metal of the fuse units 10 to 70 is mounted on the insulating substrate via the electrodes, it can be split right and left by the physical pulling action of the electrodes to quickly and surely block the electrodes. Conductive path between.

Further, since the fuse units 10 to 70 are formed by laminating the high-melting-point metal layer 12 on the low-melting-point metal layer 11 as the inner layer, the fuse can be formed by a wafer fuse or the like which is formed of a high-melting-point metal layer. The fusing temperature is greatly reduced. Therefore, the fuse units 10 to 70 can increase the sectional area and greatly increase the rated current as compared with the wafer fuse of the same size or the like. Moreover, compared with the wafer fuse having the same rated current, it is possible to reduce the size and thickness of the wafer fuse, and it is excellent in rapid fusibility.

Further, the fuse units 10 to 70 can improve the resistance (pulsation resistance) of the electric system in which the fuse element is assembled to the surge, and the surge is an abnormally high voltage applied instantaneously. That is, the fuse units 10 to 70, for example, do not blow even when the current of 100 A (amperes) passes for several msec (milliseconds). In this view, the fuse units 10 to 70 in which a large current flowing in a very short time flows on the surface of the conductor (skin effect) is provided with a high-melting-point metal layer such as Ag plating having a low resistance value as an outer layer. The current applied by the surge is easily circulated (passed) to prevent the fuse from being caused by self-heating. Therefore, the fuse units 10 to 70 can greatly improve the resistance to the surge as compared with the conventional fuse composed of the solder alloy.

Further, in the fuse units 10 to 60, it is preferable that the volume of the low-melting-point metal layer 11 is larger than the volume of the high-melting-point metal layer 12. The fuse units 10 to 60 can efficiently perform the fusing caused by the erosion of the high-melting-point metal layer in a short time by the large volume of the low-melting-point metal.

Specifically, the fuse units 10 to 60 are a coating structure of the inner layer low melting point metal layer 11 and the outer layer high melting point metal layer 12, and the layer thickness ratio of the low melting point metal layer 11 and the high melting point metal layer 12 may be It is a low melting point metal layer 11: a high melting point metal layer 12 = 10:1 to 3:1. Thereby, the volume of the low-melting-point metal layer 11 can be surely made larger than the volume of the high-melting-point metal layer 12, and the melting by the erosion of the high-melting-point metal layer can be effectively completed in a short time.

That is, the fuse units 10 to 60 have the high melting point metal layer 12 on the upper and lower surface layers of the low melting point metal layer 11 constituting the inner layer, so that the layer thickness ratio is set to the low melting point metal layer 11: the high melting point metal layer 12 The extent that the low melting point metal is thickened by a range of 3:1 or more can cause the volume of the low melting point metal layer to be larger than the volume of the high melting point metal layer 12. Further, in the fuse units 10 to 60, if the layer thickness ratio is set to the low melting point metal layer 11: the high melting point metal layer 12 exceeds 10:1, the low melting point metal layer becomes thick and the high melting point metal layer becomes thin, which is high. The melting point metal layer 12 may be eroded by the molten low melting point metal layer 11 due to the heat at the time of reflow mounting.

Further, in the fuse unit 10 to 70, either or both of the low-melting-point metal layer 11 and the high-melting-point metal layer 12 in the thickness direction have a high film thickness portion and a low film thickness portion having different thicknesses, so that it can be limited in the back. weld The movement of the molten low-melting-point metal layer at the temperature at the time of the assembly can suppress the positional shift from the design of the fuse or suppress the occurrence of a defective state in which the conductor resistance of the portion of the low-melting metal is lost. Similarly, since the fuse unit 10 to 70 can be configured such that the low-melting-point metal layer 11 has a mountain portion and a valley portion in the thickness direction, it is possible to limit the low-melting-point metal layer which is melted at the temperature at the time of the reflow assembly. mobile.

[Manufacturing method of fuse unit]

The fuse units 10, 30, 50, and 70 can be formed by forming a high-melting-point metal layer 12 on the surface of the low-melting-point metal layer 11 by a plating technique, and then using a press process. For example, after the construction of Ag plating or the like is performed on the surface of the elongated solder foil, the fuse units 10, 30, 50, and 70 can be efficiently manufactured by press working, and when used, corresponding to the size. It can be easily used by cutting.

Further, the fuse units 20, 40, and 60 are formed into a predetermined shape by using a metal material composed of the low-melting-point metal layer 11 by press working, and a high melting point is formed on the surface of the low-melting-point metal layer 11 by using a plating technique. The metal layer 12 is formed into a film for fabrication.

Further, the fuse units 10 to 70 may be manufactured by laminating a low melting point metal foil and a high melting point metal foil. The fuse units 10 to 70 can be manufactured, for example, by sandwiching a solder foil which has been rolled in the same manner between two rolled Cu foils or Ag foils after rolling and pressing. In this case, the low melting point metal foil is preferably a material which is softer than the high melting point metal foil. Thereby, the difference in thickness can be absorbed, and the low-melting-point metal foil and the high-melting-point metal foil can be adhered together without a gap. Also, a film of a low melting point metal foil Thickness is thinned by press working, so it can be thickened in advance. When the press-forming process causes the low-melting-point metal foil to be exposed (extruded) from the end face of the fuse unit, it is preferable to cut it off to make the shape neat.

Alternatively, the fuse units 10 to 70 may be formed by laminating the high melting point metal layer 12 on the low melting point metal layer 11 by a film forming technique such as vapor deposition or other conventional lamination technique to form a fuse unit.

[Application example of fuse unit]

Next, an application example of the fuse units 10 to 70 will be described. In the following description, an application example of the fuse unit 10 will be described as a representative example of the fuse units 10 to 70. However, this application example can of course be applied to other fuse units 20 to 70.

The fuse unit 10 may be configured as a fuse unit 10' as shown in Fig. 5, and the outer peripheral portion except the two end faces of the low-melting-point metal layer 11 may be covered with the high-melting-point metal layer 12. As shown in Fig. 6, when the high-melting-point metal layer 12 is the outermost layer, the oxidation preventing film 13 may be further formed on the surface of the outermost high-melting-point metal layer 12. The fuse unit 10 is further coated with the oxidation preventing film 13 on the outermost high melting point metal layer 12, for example, even when the high melting point metal layer 12 is formed by Cu plating or Cu foil. Oxidation. Therefore, the fuse unit 10 can prevent the fuse time caused by the oxidation of Cu from becoming long, and can be blown in a short time.

Further, the fuse unit 10 can be formed by using a metal such as Cu which is inexpensive and easily oxidized as the high-melting-point metal layer 12, or a high-priced metal such as Ag.

Further, as the oxidation preventing film 13, the same metal material as the inner layer of the low melting point metal layer 11 can be used. For example, a Pb-free solder containing Sn as a main component can be used. Further, the oxidation preventing film 13 can be formed by applying Sn plating to the surface of the high melting point metal. Alternatively, the oxidation preventing film 13 can be formed by Au plating or preflux.

Further, as shown in Fig. 7, the fuse unit 10 may be provided with a protective member 14 on at least a part of the outer circumference. The protective member 14 prevents the inflow of the connection solder or the outflow of the built-in low-melting-point metal layer 11 to maintain the shape when the reflow assembly of the fuse unit 10 is performed, and prevents the molten solder from being passed when the current exceeding the rated current passes. Inflow to prevent a decrease in rapid fusibility due to an increase in rated current.

That is, the fuse unit 10 is provided with the protective member 14 on the outer circumference, thereby preventing the outflow of the low-melting-point metal layer 11 which is melted at the reflow temperature, and maintaining the cell shape. In particular, in the fuse unit 10 in which the high-melting-point metal layer 12 is formed on the upper surface and the lower surface layer of the low-melting-point metal layer 11 and the low-melting-point metal layer is exposed from the side surface, the protective member 14 is provided on the outer peripheral portion, whereby the low melting point metal can be prevented from being The sides flow out to maintain the shape.

Further, the fuse unit 10 is provided with a protective member on the outer circumference, whereby the inflow of the molten solder can be prevented when a current exceeding the rated current passes. When the fuse unit 10 is soldered to the electrode, if the solder for electrode connection or the metal constituting the low-melting-point metal layer 11 is melted due to heat generation due to the passage of a current exceeding the rated current, there is a fear that the inflow should be blown. The central portion of the fuse unit 10. The fuse unit 10, if the resistance value is caused by the inflow of molten metal such as solder When the temperature is lowered, the heat generation is hindered, and it is feared that the fuse may not be blown at a predetermined current value, or the fuse time may be prolonged, or the insulation reliability between the electrodes may be impaired after the fuse. Therefore, the fuse unit 10 is provided with the protective member 14 on the outer circumference, thereby preventing the inflow of the molten metal to fix the resistance value, and can be quickly blown at a predetermined current value and the insulation reliability between the electrodes can be ensured.

Therefore, as the protective member 14, a material having insulating properties and heat resistance at the reflow temperature and having resistance to molten solder or the like is preferably used. Examples of the resin exhibiting insulating properties include polyimine, polypropylene, polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, polystyrene, styrene-acrylonitrile copolymer, and styrene. Methyl methacrylate copolymer, polymethyl methacrylate, cellulose acetate, polyamine, phenolic resin, melamine resin, oxime resin, unsaturated polyester, and the like. These insulating resins may be used singly or in combination of plural kinds. Further, for example, a polyimine film can be used and attached to the central portion of the strip-shaped fuse unit 10 as a protective member by an adhesive to form the fuse unit 10 having the protective member. Further, an insulating, insulating, and resistive ink can be applied to the outer periphery of the fuse unit to form a protective member, or a protective resist can be formed by applying a solder resist to the outer periphery of the fuse unit.

The protective member made of the film, the ink, the solder resist, or the like can be attached or coated on the outer circumference of the elongated fuse unit, and when it is used, the fuse unit provided with the protective member can be cut off. It is also excellent in usability.

Further, as the protective member, as shown in Fig. 8, the protective case 17 to which the fuse unit 10 is to be housed may be used. As shown in Fig. 8(a), the protective case 17 is composed of, for example, a frame 16 that is opened on the upper surface and a cover 15 that covers the upper surface of the frame. The protective case 17 has an opening so that both ends of the fuse unit connected to the electrode are led outward. The protective case 17 is closed except for the opening of the fuse unit, and prevents molten solder or the like from entering the casing. The protective case 17 can be formed using an engineering plastic having insulation, heat resistance, and resistance.

As shown in Fig. 8(b), the protective case 17 houses the fuse unit 10 from the upper side of the opening of the frame 16, and is formed by the closing of the lid 15 as shown in Fig. 8(c). The fuse unit 10, which is connected to the electrodes, is bent to the lower end and is led out from the side of the frame 16. The casing 16 is formed by the convex portion formed on the inner surface of the lid body 15 and the side surface of the casing 16 by the closing of the lid body 15, thereby ejecting the fuse unit 10.

The fuse unit provided with the protective member 14 or the protective case 17 can be directly mounted on the circuit board of the electronic component as a fuse element, in addition to being assembled in the fuse element.

[fuse element]

Next, a description will be given of the fuse element 100 to which the present invention is applied. Fig. 9 is a schematic cross-sectional view showing the cross-sectional shape of the fuse element 100. As shown in FIG. 9, the fuse element 100 includes an insulating substrate 101, a fuse unit 10, and a first electric power provided on the insulating substrate 101. The pole 102 and the second electrode 103 are covered by a cover member 107, and the fuse unit 10 is configured to span between the first electrode 102 and the second electrode 103, and when a current exceeding a rated current passes It will be blown by self-heating to block the conductive path between the first electrode 102 and the second electrode 103. In the following description, an application example of the fuse unit 10 will be described as a representative example of the fuse units 10 to 70. However, this application example can of course be applied to other fuse units 20 to 70.

The insulating substrate 101 is formed into a square shape by, for example, an insulating member such as alumina, glass ceramic, mullite, or zirconia. In addition, as the insulating substrate 101, a material used for a so-called substrate for a printed circuit such as a glass epoxy substrate or a phenol substrate may be used.

Further, the first electrode 102 and the second electrode 103 are formed on both end portions of the insulating substrate 101 facing each other. Each of the first electrode 102 and the second electrode 103 is formed of a conductive pattern such as a Cu circuit, and a protective layer 104 such as Sn plating is appropriately provided on the surface thereof as a countermeasure against oxidation. Further, the first electrode 102 and the second electrode 103 reach the back surface 101b from the front surface 101a of the insulating substrate 101 via the side surface. The fuse element 100 is mounted on a current circuit of the circuit board via the first electrode 102 and the second electrode 103 formed on the back surface 101b of the insulating substrate 101.

As described above, the fuse unit 10 that is configured to straddle between the first electrode 102 and the second electrode 103 is blown by self-heating when a current exceeding a rated current passes to block the first electrode. A conductive path between the 102 and the second electrode 103. As shown in Fig. 1(a) and Fig. 1(b), the low-melting-point metal layer 11 of the fuse unit 10 has a substantially trapezoidal shape formed on both sides in the thickness direction of the low-thickness portion 11b in the cross-sectional shape. The high film thickness portion 11a and the low film thickness portion 11b and the high film thickness portion 11a are continuously formed in the longitudinal direction. Further, the high-melting-point metal layer 12 of the fuse unit 10 is laminated to have a predetermined thickness corresponding to the outer shape of the low-melting-point metal layer 11. The fuse unit 10 having such a configuration is attached to the first electrode 102 and the second electrode 103 via a bonding material 105 such as solder, and then connected to the insulating substrate 101 by application of solder reflow or the like. At this time, since the low-melting-point metal layer 11 of the fuse unit 10 has a high film thickness portion and a low film thickness portion having different thicknesses, the movement of the molten low-melting-point metal layer can be restricted at the temperature at the time of reflow soldering. The positional deviation from the design of the fuse is suppressed, or the occurrence of a defective state in which the conductor resistance of the portion where the low-melting metal is lost is suppressed.

Further, in the fuse element 100 of the present invention, a single fuse unit 10 is separately formed outside the insulating substrate 101, and the fuse unit 10 is configured to be separated from the surface 101a of the insulating substrate 101. Therefore, even when the fuse unit 10 is blown, the fuse element 100 does not erode into the insulating substrate 101 and is introduced into the first electrode 102 and the second electrode 103, so that the first electrode 102 can be surely The second electrodes 103 are insulated from each other.

Further, in the fuse element 100 according to the present invention, the flux 106 may be applied to substantially the entire surface of the outer layer of the fuse unit 10. By applying the flux 106, it is possible to increase the low The melting point of the metal layer 11 of the melting point, and the removal of the oxide during the melting of the low melting point metal, and promotes the erosion of the high melting point metal. In addition, even when the flux 106 is formed on the surface of the outermost high-melting-point metal layer 12 as the oxidation preventing film of the lead-free solder whose main component is Sn, the oxide of the oxidation preventing film can be removed. The oxidation of the high melting point metal layer 12 is prevented.

Further, as the fuse element 100 according to another aspect of the present invention, as shown in FIG. 10, the fuse unit 10 may be configured by a clip-shaped adhesive material 105 connected to the first electrode 102 and the second electrode 103. Shape. The clip-shaped adhesive material 105 can be easily connected by pressing and holding the end of the fuse unit 10.

The fuse unit 10 that is physically fitted by the clip-shaped adhesive material 105 is assembled in the fuse element 100 and the fuse element 110 as shown in FIGS. 9 and 10, for example, as in the eleventh As shown in the figure, it is possible to directly assemble itself into a fuse box or a breaker device by using itself as a fuse element. In this case, the fuse unit 10 holds the first wire terminal 112 and the second wire terminal 113 disposed on the insulated terminal block 111 by the clamp terminal 108, and clamps the terminal 108 through the wire terminal 112, 113 and the bolt 114 of the insulating terminal block 111 and the fastener 115 which is disposed on the back surface of the insulating terminal block 111 are fixed.

[Test of the effect of the movement inhibition of low melting point metals]

Next, a test for the effect of suppressing the movement of the low melting point metal to which the fuse unit of the present invention is applied will be described. Figure 12(a), as this test The reference example used in the examination is a schematic cross-sectional view showing the cross-sectional shape of the fuse unit 200 in which the high-melting-point metal layer 12 is laminated on both surfaces of the low-melting-point metal layer 11. Fig. 12(b) is a representative example of the present invention, and corresponds to the fuse unit 10 shown in Fig. 1(a), and shows that the low-melting-point metal layer 11 has one high-thickness portion 11a and two places. A schematic cross-sectional view of the cross-sectional shape of the fuse unit 300 of the low-thickness portion 11b.

The fuse unit 200 shown in Fig. 12(a) and the fuse unit 300 shown in Fig. 12(b) are each subjected to the following test: heating at a normal set temperature of 240 ° C at the time of reflow soldering After 4 minutes, the presence or absence of movement of the low melting point metal was confirmed by X-ray image.

As a result, in the fuse unit 200 in which the high-melting-point metal layer 12 is laminated only on both surfaces of the low-melting-point metal layer 11, the thickness of the low-melting-point metal is thinned by heating for 4 minutes, and it is confirmed that it is uncontrollable. The movement of low melting point metals. On the other hand, in the fuse unit 300 in which the low-melting-point metal layer 11 has the high-thickness portions 11a and 2 at the high-thickness portions 11a and 2, the low-thickness portion 11b is blocked even after heating for 4 minutes. The movement of the low melting point metal confirms that the movement of the low melting point metal can be controlled.

As described above, according to the fuse unit and the fuse element of the present invention, it is possible to provide a fuse unit and a fuse element which can suppress the fuse even if the low melting point metal is melted at the temperature at the time of the reflow assembly. The positional shift from the design or the occurrence of a defective state in which the conductor resistance of the portion where the low melting point metal is lost is suppressed.

10‧‧‧Fuse unit

11‧‧‧Low-melting metal layer

11a‧‧‧High film thickness

11b‧‧‧Low film thickness

12‧‧‧High melting point metal layer

12a‧‧‧High film thickness

12b‧‧‧low film thickness

20‧‧‧Fuse unit

Claims (10)

A fuse unit constituting a conductive path of a fuse element, which is blown by self-heating due to passage of a rated current, and has a low-melting-point metal layer and a high-melting-point metal layer laminated on the low-melting-point metal layer, wherein The low-melting-point metal layer functions to erode and melt the high-melting-point metal layer, and the fuse unit is characterized in that either or both of the low-melting-point metal layer and the high-melting-point metal layer have different thicknesses Thick film portion and low film thickness portion. The fuse unit according to claim 1, wherein only the low-melting-point metal layer has a high film thickness portion and a low film thickness portion having different thicknesses. The fuse unit according to claim 1, wherein only the high-melting-point metal layer has a high film thickness portion and a low film thickness portion having different thicknesses. The fuse unit according to any one of claims 1 to 3, wherein the high film thickness portion and the low film thickness portion are continuously formed in the longitudinal direction. The fuse unit according to any one of claims 1 to 4, wherein the high film thickness portion has a thickness twice or more with respect to the low film thickness portion. A fuse unit constituting a conductive path of a fuse element, which is blown by self-heating due to passage of a rated current, and has a low-melting-point metal layer and a high-melting-point metal layer laminated on the low-melting-point metal layer, wherein The above-mentioned low-melting-point metal layer serves to erode and melt the above-mentioned high-melting-point metal layer, and the fuse unit is characterized in The low-melting-point metal layer has a mountain portion and a valley portion in the thickness direction. The fuse unit according to claim 6, wherein the mountain portion and the valley portion are continuously formed in the longitudinal direction. The fuse unit according to any one of claims 1 to 7, wherein the low melting point metal layer is solder; the high melting point metal layer is Ag, Cu, or an alloy containing Ag or Cu as a main component. The fuse unit according to any one of claims 1 to 8, wherein a ratio of a layer thickness of the low melting point metal layer to the high melting point metal layer is a low melting point metal layer: a high melting point metal layer = 10:1 ~3:1. A fuse element comprising: an insulating substrate; and a fuse unit mounted on the insulating substrate to be blown by self-heating due to passage of a rated current; and the fuse unit has a low melting point metal layer, And a high melting point metal layer laminated on the low melting point metal layer, wherein the low melting point metal layer serves to erode and melt the high melting point metal layer, and the fuse element is characterized by: the low melting point metal layer And either or both of the high-melting-point metal layers have a high film thickness portion and a low film thickness portion having different thicknesses.