JP2023126322A - circuit module - Google Patents

Abstract

To provide a circuit module which makes damage less likely to occur in a periphery of a fuse element even if heat and arc which are generated during fusion of a fusible conductor of the fuse element are emitted to the outside.SOLUTION: A circuit module 1 includes: a circuit board 2; an insulative protection member 3 disposed on the circuit board 2; and a fuse element 4 mounted on the circuit board 2 through the insulative protection member 3. The fuse element 4 includes: an insulation substrate 40; and a case 50 which covers a surface of the insulation substrate 40. The case 50 has through holes 52 on a side surface 51. The fuse element 4 is disposed at the inner side relative to an outer periphery of the insulative protection member 3 when viewed in a plan view. The insulative protection member 3 has a plate-like shape and an outer periphery of the insulative protection member 3 is erected in a wall-like shape.SELECTED DRAWING: Figure 2

Description

The present invention relates to a circuit module in which a fuse element is mounted.

Conventionally, fuse elements have been used as protection elements for various electrical devices equipped with secondary batteries, such as electronic devices such as mobile phones and portable computers, and rechargeable electric devices. As a fuse element, a first electrode and a second electrode formed on the surface of an insulating substrate are connected between the first electrode and the second electrode, and when the fuse element is blown, a gap between the first electrode and the second electrode is formed. A configuration is known that includes a fusible conductor that blocks . In a fuse element having such a configuration, when an overcurrent flows through the fusible conductor, the fusible conductor self-heats and fuses. In addition, there is also a structure in which a heating element is provided inside the fuse element, and the fusible conductor can be fused at the timing intended by the circuit side by energizing the heating element installed inside the fuse element in response to an external signal. It is being

Components such as the first electrode, second electrode, and fusible conductor arranged on the surface of the insulating substrate of the fuse element are usually covered with a case, which protects the inside of the case and makes handling easier. Improving. However, if the components of the fuse element are covered with a case, the inside of the case may become hot due to heat generated when the fusible conductor melts due to overcurrent or the like, and the air inside the case may expand rapidly. In order to prevent damage to the case due to the expansion of heat and air, a through hole is provided in the case to release air and heat that rapidly expands inside the case to the outside (Patent Document 1).

Japanese Patent Application Publication No. 2016-134317

BACKGROUND ART With the increase in voltage and output of electrical equipment in recent years, the amount of heat generated when the fusible conductor of a fuse element is fused tends to increase, and arc discharge may occur when the soluble conductor is fused. For this reason, it is effective to provide a through hole in the case of the fuse element so that the arc can be released to the outside together with the air and heat expanded inside the case. However, if heat or arc is emitted to the outside from the through hole of the case, there is a risk of damaging the circuit board surrounding the fuse element, such as partially melting the wiring pattern. On the other hand, as electrical equipment becomes smaller and lighter, fuse elements are required to be smaller. Therefore, in order to satisfy the demands for higher voltage, higher output, smaller size, and lighter weight in electrical equipment, and to be able to operate the fuse element without damaging the surrounding area, it is necessary to The situation is difficult to deal with simply by making improvements.

The present invention has been made in view of the above circumstances, and provides a circuit module that is less likely to cause damage to the area around the fuse element even if the heat and arc generated when the fusible conductor of the fuse element melts is released to the outside. The purpose is to provide.

The present invention provides the following means to solve the above problems.

(1) A circuit module according to one aspect of the present invention includes a circuit board having a wiring pattern, an insulating protection member disposed on the circuit board, and a circuit board disposed on the circuit board via the insulating protection member. and a fuse element mounted on an insulating substrate, a plurality of surface electrodes formed on a surface of the insulating substrate, and a fuse element connected between the plurality of surface electrodes, and the fuse element is connected between the plurality of surface electrodes by blowing. , a plurality of back electrodes formed on the back surface of the insulating substrate and electrically connected to the plurality of surface electrodes, and a case covering the front surface of the insulating substrate. The case has a through hole on a side surface or a top surface, and the fuse element is disposed inside the outer periphery of the insulating protection member when viewed from above.

(2) In the aspect described in (1) above, the insulating protection member may have a flat plate shape.
(3) In the aspect described in (1) or (2) above, the insulating protection member includes a conductive portion that electrically connects the back electrode of the fuse element and the wiring pattern of the circuit board. Good as a structure.
(4) In the aspect described in (3) above, the conductive portion is a conductive through hole provided in the plane of the insulating protection member, or a conductive through hole provided in the outer peripheral portion of the insulating protection member. It may also be configured as a side through hole.

According to the present invention, it is possible to provide a circuit module that does not easily damage the area around the fuse element even if heat and arc generated when the fusible conductor of the fuse element is blown are released to the outside.

FIG. 1 is a plan view of a circuit module according to an embodiment of the present invention. 2 is a sectional view taken along the line II-II in FIG. 1. FIG. FIG. 2 is a plan view showing a fuse element of the circuit module shown in FIG. 1 with a case omitted. 2 is a perspective view of a fuse element of the circuit module shown in FIG. 1. FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a circuit module according to the present invention will be described in detail with appropriate reference to the drawings. In the drawings used in the following explanation, characteristic parts may be shown enlarged for convenience in order to make the characteristics easier to understand, and the dimensional ratio of each component may be different from the actual one. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and can be implemented with appropriate changes within the scope of achieving the effects of the present invention.

FIG. 1 is a plan view of a circuit module according to an embodiment of the present invention. 2 is a sectional view taken along the line II-II in FIG. 1, FIG. 3 is a plan view showing the fuse element shown in FIG. 1 with the case omitted, and FIG. 4 is a cross-sectional view of the fuse element shown in FIG. FIG.

As shown in FIGS. 1 and 2, the circuit module 1 of this embodiment includes a circuit board 2, an insulating protection member 3 disposed on the circuit board, and a circuit board 2 connected to the circuit board 2 via the insulating protection member 3. and a fuse element 4 mounted thereon. The fuse element 4 is arranged inside the outer periphery of the insulating protection member 3 when viewed from above.

[Circuit board]
The circuit board 2 includes an insulating sheet 20 and wiring patterns 21a, 21b, 21c, and 22 formed on the surface of the insulating sheet 20. The wiring patterns 21a, 21b, and 21c are wiring patterns connected to the fuse element 4, and the wiring pattern 22 is a wiring pattern not connected to the fuse element 4. The insulating sheet 20 is not particularly limited as long as it has electrical insulation properties, and any known insulating sheet used in circuit boards, such as a resin sheet, a ceramic sheet, or a composite sheet of resin and ceramic particles, can be used. . Examples of resin sheets include epoxy resin sheets, phenol resin sheets, and polyimide sheets. Examples of ceramic sheets include alumina sheets, glass ceramic sheets, mullite sheets, and zirconia sheets. Examples of composite sheets include glass epoxy sheets. As the material for the wiring patterns 21a, 21b, 21c, and 22, common electrode materials such as Cu and Ag can be used.

[Insulating protection member]
The insulating protection member 3 has a function of protecting the wiring patterns 21a, 21b, 21c, and 22 of the circuit board 2 from heat and arc released from the fuse element 4. Therefore, the outer circumference of the insulating protection member 3 is wider than the outer circumference of the fuse element 4. The distance between the outer periphery of the insulating protection member 3 and the outer periphery of the fuse element 4 varies depending on the size of the fuse element 4 and the usage conditions of the circuit module 1, but is generally within a range of 2 to 3 times the outer diameter of the fuse element 4. It is preferable that the

It is preferable that the insulating protection member 3 has a flat plate shape. The thickness of the insulating protection member 3 varies depending on the heat resistance and thermal conductivity of the insulating protection member 3, but is generally preferably within the range of 100 μm to 1000 μm. Further, the outer periphery of the insulating protection member 3 may be raised up like a wall.

The insulating protection member 3 includes a non-conductive part 30 and a conductive part 31. The conductive portion 31 electrically connects the wiring patterns 21 a, 21 b, and 21 c of the circuit board 2 to the first electrode 41 , the second electrode 42 , and the first heating element electrode 43 of the fuse element 4 . The non-conductive portion 30 is preferably made of a ceramic material that has excellent heat resistance and thermal conductivity. Examples of ceramic materials include alumina, glass ceramics, mullite, and zirconia. As the material of the conductive part 31, general electrode materials such as Cu and Ag can be used. In this embodiment, the conductive portion 31 is in the form of a conductive through hole provided within the plane of the insulating protection member 3 . However, the form of the conductive part 31 is not particularly limited, and may be a conductive side through hole provided in the outer peripheral part of the insulating protection member 3.

[Fuse element]
Fuse element 4 has an insulating substrate 40. The insulating substrate 40 has a first electrode 41, a second electrode 42, a first heating element electrode 43, and a second heating element electrode 44 formed thereon. The first electrode 41 includes a first front electrode 41a formed on the front surface 40a of the insulating substrate 40, a first back electrode 41c formed on the back surface 40b of the insulating substrate 40, a first front electrode 41a and a first back electrode. 41c and a castellation 41b. The second electrode 42 includes a second front electrode 42a formed on the front surface 40a of the insulating substrate 40, a second back electrode 42c formed on the back surface 40b of the insulating substrate 40, a second front electrode 42a and a second back electrode. 42c, and a castellation 42b connecting to the castellation 42c. The first heating element electrode 43 includes a first heating element front electrode 43a formed on the front surface 40a of the insulating substrate 40, a first heating element back electrode 43c formed on the back surface 40b of the insulating substrate 40, and a first heating element back electrode 43c formed on the back surface 40b of the insulating substrate 40. It consists of castellations 43b connecting the front surface electrode 43a and the first heating element back surface electrode (not shown). The second heating element electrode 44 consists only of a second heating element surface electrode 44a formed on the surface 40a of the insulating substrate 40.

A fusible conductor 45 is electrically connected between the first surface electrode 41a and the second surface electrode 42a, and cuts off the first surface electrode 41a and the second surface electrode 42a by being fused. The first back electrode 41c is electrically connected to the wiring pattern 21a, the second back electrode 42c is electrically connected to the wiring pattern 21b, and the first heating element back electrode is electrically connected to the wiring pattern 21c through the conductive part 31 of the insulating protection member 3. It is connected. The wiring pattern 21c is electrically connected to an external control element (not shown), and current is supplied to the first heating element electrode 43 in response to a signal from the control element.

Further, the front surface 40a of the insulating substrate 40 is provided with a heating element 46 and an insulating member 47 covering the heating element 46. A heating element extraction electrode 48 is formed on the insulating member 47 so as to face the heating element 46 . One end of the heating element 46 is electrically connected to the first heating element surface electrode 43a, and the other end is electrically connected to the second heating element surface electrode 44a. One end of the heating element extraction electrode 48 is electrically connected to the second heating element surface electrode 44a, and is also electrically connected to the soluble conductor 45.

Flux 49 is applied to the surface of the fusible conductor 45 to prevent oxidation, improve wettability, and the like.

The fuse element 4 includes a case 50 that covers the surface 40a of the insulating substrate 40. Case 50 has a side surface 51 bonded onto the surface of insulating substrate 40 and a top surface 53 covering the surface of insulating substrate 40 . The case 50 is provided with a through hole 52 only on a side surface 51. Although there is no particular restriction on the number or size of the through holes 52, it is preferable that one or more through holes 52 are provided on each of the four side surfaces 51 of the case 50.

The case 50 is preferably made of a ceramic material that has excellent heat resistance and thermal conductivity. Examples of ceramic materials include alumina, glass ceramics, mullite, and zirconia.

The first electrode 41, the second electrode 42, the first heating element electrode 43, and the second heating element electrode 44 can be formed using common electrode materials such as Cu and Ag. Further, the surfaces of the first electrode 41 and the second electrode 42 are coated with a film such as Ni/Au plating, Ni/Pd plating, Ni/Pd/Au plating, etc. by a known method such as plating treatment. It is preferable. Thereby, oxidation of the first electrode 41 and the second electrode 42 can be prevented, and fluctuations in rating due to increase in conduction resistance can be prevented. Furthermore, when the fuse element 4 is reflow mounted, the connecting solder that connects the first electrode 41 and the second electrode 42 to the fusible conductor 45 or the low melting point metal that forms the outer layer of the fusible conductor 45 may melt. The first electrode 41 and the second electrode 42 can be prevented from being eroded (solder eaten away).

The fusible conductor 45 is made of a material that quickly melts due to self-heating (Joule heat) when an overcurrent flows or due to the heat generated by the heating element 46, such as solder or Pb-free solder whose main component is Sn. , In, and other low melting point metals can be suitably used. Further, the fusible conductor 45 may be made of a high melting point metal such as Pb, Ag, Cu, or an alloy containing any of these as a main component, or a laminate of a low melting point metal and a high melting point metal. There may be. By containing a high melting point metal and a low melting point metal, when reflow mounting the fuse element 4, even if the reflow temperature exceeds the melting temperature of the low melting point metal and the low melting point metal melts, the low melting point metal It is possible to suppress leakage to the outside and maintain the shape of the fusible conductor 45. Furthermore, when cutting, the melting of the low melting point metal causes the high melting point metal to be eroded (solder eaten), so that the melting point can be quickly cut at a temperature below the melting point of the high melting point metal.

The heating element 46 is a conductive member that generates heat when energized, and is made of, for example, a high-resistance material such as W, Mo, Ru, Cu, Ag, an alloy containing these as main components, or a composition or compound containing these. Made of conductive material. The heating element 46 may be formed by forming a pattern on the insulating substrate 40 using a screen printing technique using a paste prepared by mixing powder of a high-resistance conductive material and a resin binder, and then firing the paste. I can do it.

As the insulating member 47, for example, glass can be used.
The heating element extraction electrode 48 has a function of transmitting the heat generated by the heating element 46 to the soluble conductor 45 via the second heating element surface electrode 44a. As the material of the heating element extraction electrode 48, a metal material with high thermal conductivity such as Cu or Ag can be used. Further, in order to efficiently transfer the heat of the heating element 46 to the fusible conductor 45, an insulating member may be interposed between the heating element 46 and the insulating substrate 40.

The circuit module 1 of this embodiment can be manufactured, for example, as follows. First, a circuit board 2 having wiring patterns 21a, 21b, and 21c at positions corresponding to the first electrode 41, second electrode 42, and first heating element electrode 43 of the fuse element 4, and An insulating protection member 3 having a conductive portion 31 corresponding to the first electrode 41, the second electrode 42, and the first heating element electrode 43, and whose back side corresponds to the wiring patterns 21a, 21b, and 21c of the circuit board 2 is prepared.

The insulating protection member 3 is mounted on the prepared circuit board 2, and solder is placed between the wiring patterns 21a, 21b, 21c of the circuit board 2 and the conductive portion 31 of the insulating protection member 3. Next, the fuse element 4 is mounted on the insulating protection member 3, and between the conductive part 31 of the insulating protection member 3 and the first electrode 41, second electrode 42, and first heating element electrode 43 of the fuse element 4. Place the solder on the Then, by heating the solder in a reflow oven, the wiring patterns 21a, 21b, 21c of the circuit board 2 and the first electrode 41, second electrode 42, and first heating element electrode 43 of the fuse element 4 are insulated. It is electrically connected via the conductive part 31 of the sexual protection member 3.

The circuit module 1 of this embodiment can be used, for example, as a protection circuit for a battery pack of a lithium ion secondary battery. The circuit module 1 of this embodiment is difficult to damage the area around the fuse element 4 even if an arc occurs in the fuse element 4, so it can be advantageously used as a protection circuit for a battery pack of an electrical device that uses a large current. can do. Electrical devices that use large currents include electrical devices that use large currents exceeding several 10A to 100A, such as power tools such as electric screwdrivers, transportation equipment such as hybrid cars, electric vehicles, and electrically assisted bicycles. can be mentioned.

In the circuit module 1 of this embodiment configured as described above, when an overcurrent flows through the wiring patterns 21a, 21b of the circuit board 2, the first electrode 41 of the fuse element 4 connected to the wiring patterns 21a, 21b An overcurrent flows through the fusible conductor 45 connecting the second electrode 42 and the second electrode 42 . When an overcurrent flows through the fusible conductor 45, the fusible conductor 45 self-heats, melts, and is fused, cutting off the current path within the circuit module 1.

Furthermore, in the circuit module 1 of this embodiment, when a malfunction such as an abnormality in the battery voltage value is detected within the circuit module 1, a signal from an external control element (not shown) causes the first heat generation to be activated. A current is supplied to the body electrode 43. As a result, the heating element 46 generates heat, the heat is transmitted to the fusible conductor 45 via the second heating element surface electrode 44a and the heating element extraction electrode 48, and the fusible conductor 45 is melted, causing fusing. As a result, the current path within the circuit module 1 is cut off.

In the circuit module 1 of this embodiment, the through hole 52 is formed in the side surface 51 of the case 50 of the fuse element 4, so that the heat generated when the fusible conductor 45 is fused, the air expanded by the heat, and the arc can pass through. It is released from the hole 52. Therefore, the case 50 is less likely to be damaged when the fusible conductor 45 is fused. Further, in the circuit module 1 of this embodiment, the fuse element 4 is arranged inside the outer periphery of the insulating protection member 3 when viewed from above, and the surface of the circuit board 2 around the fuse element 4 is insulated. It is protected by a sex protection member 3. Therefore, even if the heat and arc generated when the fusible conductor 45 of the fuse element 4 is blown out is released to the outside through the through hole 52, the area around the fuse element 4 is unlikely to be damaged.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described within the scope of the claims. is possible.
In this embodiment, the fuse element 4 has the fusible conductor 45 connected between the first electrode 41 and the second electrode 42, but the number of electrodes is not limited as long as it is two or more. For example, a further pair of electrodes may be provided and another soluble conductor may be connected between the pair of electrodes.
Further, in this embodiment, the through hole 52 is provided only on the side surface 51 of the case 50, but the through hole 52 may be provided on the top surface 53.

1 Circuit module 2 Circuit board 3 Insulating protection member 4 Fuse element 20 Insulating sheet 21a, 21b, 21c, 22 Wiring pattern 30 Non-conductive part 31 Conductive part 40 Insulating substrate 40a Front surface 40b Back surface 41 First electrode 41a First surface electrode 41b Castellation 41c First back electrode 42 Second electrode 42a Second front electrode 42b Castellation 42c Second back electrode 43 First heating element electrode 43a First heating element surface electrode 43b Castellation 44 Second heating element electrode 44a Second heating element Body surface electrode 45 Fusible conductor 46 Heating element 47 Insulating member 48 Heating element extraction electrode 49 Flux 50 Case 51 Side 52 Through hole 53 Top surface

Claims (3)

a circuit board having a wiring pattern;
an insulating protection member disposed on the circuit board;
a fuse element mounted on the circuit board via the insulating protection member,
The fuse element is
an insulating substrate;
a plurality of surface electrodes formed on the surface of the insulating substrate;
a fusible conductor that is connected between the plurality of surface electrodes and cuts off the connection between the plurality of surface electrodes by being fused;
a plurality of back electrodes formed on the back surface of the insulating substrate and electrically connected to the plurality of front electrodes;
and a case that covers the surface of the insulating substrate,
The case has a through hole on the side surface,
The fuse element is arranged inside the outer periphery of the insulating protection member when viewed in plan,
In the circuit module, the insulating protection member has a flat plate shape, and the outer periphery of the insulating protection member stands up like a wall. 3. The circuit module according to claim 1, wherein the insulating protection member includes a conductive part that electrically connects the back electrode of the fuse element and the wiring pattern of the circuit board. 4. The conductive portion is a conductive through hole provided in the plane of the insulating protection member, or a conductive side through hole provided in the outer peripheral portion of the insulating protection member. circuit module.

Images