CN109496343B - Protection element, circuit module, and method for manufacturing protection element - Google Patents

Abstract

In a protective element having a space inside a cover and a circuit module having the protective element mounted thereon, damage of an electronic component is prevented by preventing a decrease in adhesive strength of a cover member due to expansion of internal air, and inflow of sealing resin, cleaning liquid, or the like is prevented. The disclosed device is provided with: an insulating substrate (10); 1 st and 2 nd electrodes (11, 12) provided on an insulating substrate (10); a fusible conductor (13) disposed across the 1 st and 2 nd electrodes (11, 12); and a cover member (20) disposed on the side of the surface (10 a) of the insulating substrate (10) on which the soluble conductor (13) is disposed, wherein a vent hole (23) for causing an internal space (25) in which the soluble conductor (13) is disposed to come into contact with the outside of the element is provided, and the vent hole (23) is sealed by a sealing member (24).

Description

Protection element, circuit module, and method for manufacturing protection element

Technical Field

The present technology relates to a protection element for cutting off a power supply line and a signal line, and a circuit module having a circuit board on which the protection element is mounted.

Background

Most rechargeable batteries, which can be charged and recycled, are manufactured into battery packs and provided to users. In particular, in a lithium ion secondary battery having a high weight energy density, in order to secure safety of users and electronic devices, it is common to incorporate several protection circuits such as overcharge protection and overdischarge protection in a battery pack, and to have a function of cutting off an output of the battery pack in a predetermined case.

In such a protection element, an fet (field Effect transistor) switch incorporated in the battery pack is used to turn ON/OFF (ON/OFF) an output, thereby performing overcharge protection or overdischarge protection of the battery pack. However, even when the FET switch is short-circuited for some reason, a large current flows instantaneously due to the application of a lightning surge or the like, or when the output voltage abnormally decreases or an excessive abnormal voltage is conversely output due to the life of the battery cell, it is necessary to protect the battery pack or the electronic device from accidents such as fire. Therefore, in any conceivable abnormal state, a protection element having a function of cutting off a current path in accordance with a signal from the outside is also employed in order to safely cut off the output of the battery cell.

As a blocking element for a protection circuit of a lithium ion secondary battery or the like, as shown in fig. 17 (a) and (B), there is an element in which: the fusible conductor 93 is connected across the 1 st electrode 91, the heating element-drawing electrode 95, and the 2 nd electrode 92 on the current path to form a part of the current path, and the fusible conductor 93 on the current path is fused by self-heating by an overcurrent or the heating element 94 provided inside the protection element (see patent document 1). In the protection element 90, the fusible conductor 93 in a molten liquid state is gathered on the heating element extraction electrode 95 connected to the heating element 94 and the 1 st and 2 nd electrodes 91 and 92, thereby separating the 1 st and 2 nd electrodes 91 and 92 and blocking the current path.

In the protection element, the soluble conductor 93 is fused by heat generated by the heating element 94, and the soluble conductor 93 is also fused by self-heating due to an overcurrent, so that the fused soluble conductor 93 is sealed by the cover member 97 as an exterior member so as not to scatter. In the protection element 90, an internal space for melting and flowing the soluble conductor 93 is provided by the lid member 97 in order to stably achieve the melting action of the soluble conductor 93 by the heating element 94. Further, as shown in fig. 18, in the cover member 97, a vent hole 99 is provided in the cover member 97 in order to release a large amount of energy to the outside when the current is interrupted and prevent the destruction of the element.

In order to prevent the surface of the soluble conductor 93 from being oxidized and maintain the quick fusing property, the protective element 90 is coated with flux 98 for removing the oxide film on the surface of the soluble conductor 93.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2010-003665;

patent document 2: japanese patent laid-open No. 2001-076610.

Disclosure of Invention

Problems to be solved by the invention

The protection element 90 is mounted on a circuit board on which a power supply circuit and the like are formed, thereby constituting a part of a charge/discharge path, and the fusible conductor 93 is fused to cut off the charge/discharge path.

Here, the circuit board on which the protective element 90 is mounted is coated with resin for improving the strength and smoothness of the board, and the protective element 90 may be sealed with resin. Alternatively, the circuit board may be subjected to post-treatment such as substrate cleaning for the purpose of removing the solder or solder balls scattered on the printed board.

However, in the protection element 90, since the cover member 97 is provided with the vent hole 99, and the sealing resin or the cleaning liquid enters the inside of the vent hole 99, there is a problem that the internal space for the fusible conductor 93 to melt or flow is filled up, or the flux 98 is removed, and there is a possibility that the proper blocking function of the protection element is impaired.

Although a sealed protective element in which a lid member is not provided with a vent hole is widely distributed, when a thermosetting adhesive having a high adhesive strength is used as an adhesive for bonding the lid member, air inside the element expands during heating, and air leaks from between the uncured liquid adhesive, so that sealing with the lid member becomes impossible, and the adhesive strength of the lid member also decreases. In addition, when the sealed protective device is reflow-mounted on the circuit board, air inside the device expands, and a solvent component contained in the flux vaporizes, so that the internal pressure of the device increases, and further, the adhesive softens due to reflow heating, so that the sealing by the lid member is similarly impossible, and the adhesive strength of the lid member also decreases. Further, in the sealed type protection element, there is a risk that the element is broken because the excessive energy generated when the soluble conductor is cut cannot be discharged to the outside of the element.

In addition, a method of preventing the penetration of a sealing material or a cleaning liquid into the circuit board by sealing the protective element with resin after the open type protective element having the vent hole provided in the cover member is mounted is also considered (see fig. 19). However, in order to reliably seal the entire protective element and the peripheral portion thereof, a resin needs to be applied, and a large amount of sealing resin is required. In addition, as shown in fig. 20, when other members are attached around the protective element, it is difficult to perform coating. Further, as shown in fig. 21, since the coating is performed for each circuit board, the productivity of the circuit board is lowered.

The present technology solves the above-described problems, and an object of the present technology is to provide a protective element having a space inside a cover and a circuit module in which the protective element is mounted, which can prevent damage to an electronic component by preventing a decrease in the adhesive strength of a cover member due to expansion of the inside air, and which can prevent inflow of a sealing resin, a cleaning liquid, or the like, a circuit module in which the protective element is mounted, and a method for manufacturing the protective element.

Means for solving the problems

In order to solve the above problem, a protection element according to the present technology includes: an insulating substrate; 1 st and 2 nd electrodes provided on the insulating substrate; a soluble conductor disposed across the 1 st and 2 nd electrodes; and a lid member disposed on the side of the insulating substrate on which the soluble conductor is disposed, the lid member being provided with a vent hole for allowing an internal space in which the soluble conductor is disposed to hit the outside of the device, the vent hole being sealed by a sealing member.

Further, a circuit module according to the present technology includes: a protective element; and a circuit board having the protection element mounted on a surface thereof, the protection element including: an insulating substrate; 1 st and 2 nd electrodes provided on the insulating substrate; a soluble conductor disposed across the 1 st and 2 nd electrodes; and a lid member disposed on the side of the insulating substrate on which the soluble conductor is disposed, the lid member being provided with a vent hole for allowing an internal space in which the soluble conductor is disposed to hit the outside of the device, the vent hole being sealed by a sealing member.

In the method for manufacturing a protective device according to the present invention, the 1 st and 2 nd electrodes are formed on the insulating substrate, the soluble conductor is arranged across the 1 st and 2 nd electrodes, the cover member is mounted on the insulating substrate via the thermosetting resin, the structure having the vent hole for causing the internal space in which the soluble conductor is arranged to hit the outside of the device is formed, the cover member is connected to the insulating substrate by heating the structure, and the vent hole is sealed by the sealing member.

Effects of the invention

According to this technique, the inflation gas generated in the internal space can be released to the outside when the cover member is connected or the like. In addition, since the vent hole is sealed by the sealing member after the lid member is attached, the sealing resin applied to the circuit board or the cleaning liquid applied to the circuit board can be prevented from entering the device through the vent hole, and a proper blocking function as a protective element can be maintained. Further, since the protection element is sealed by the sealing member in the vent hole, the connection strength between the cover member and the insulating substrate can be improved, and the cover member can be prevented from being peeled off from the insulating substrate or damaged even when the internal pressure is increased by the expansion of air in the element at the time of reflow mounting to the circuit substrate or at the time of fusing the fusible conductor.

Drawings

Fig. 1 is an external perspective view showing a protective element to which the present technology is applied.

Fig. 2 is a sectional view showing a circuit module to which the present technique is applied.

Fig. 3 is a plan view on the surface of an insulating substrate showing a protective element with a cover member omitted.

Fig. 4 is an external perspective view showing a protective element to which the present technology is applied from the back side.

FIG. 5 is a sectional view showing a manufacturing process of a protective element to which the present technique is applied, wherein (A) shows a state in which various electrodes, heating elements, and fusible conductors are arranged on an insulating substrate; (B) showing a state of mounting the cover member; (C) showing a state in which the sealing member is supplied to the vent hole.

Fig. 6 is a view showing a protective member provided with a protrusion on a partition wall, where (a) is an external perspective view and (B) is a sectional view.

Fig. 7 is a view showing a protection element in which a 2 nd projecting portion projecting toward an insulating substrate side is further provided on a projecting portion of a partition wall, (a) is an external perspective view, and (B) is a sectional view.

Fig. 8 is a view showing a protective member having a tapered portion provided in a partition wall, (a) is an external perspective view, and (B) is a sectional view.

Fig. 9 is a view showing a protective element in which a partition wall member is disposed, (a) is an external perspective view, and (B) is a sectional view.

Fig. 10 is a view showing a protective element package according to a reference example, where (a) is an external perspective view and (B) is a cross-sectional view.

Fig. 11 is a view showing a protective device in which a cover member having no top surface is used and thermosetting resin is filled up to the top surface of a partition wall member, where (a) is an external perspective view and (B) is a sectional view.

Fig. 12 is a view showing a protective element after sealing a vent hole by disposing a thermosetting resin and a fitting pin in the vent hole, (a) is an external perspective view, and (B) is a sectional view.

Fig. 13 is a view showing a protection element in which a fitting pin inserted into a vent hole is connected to an insulating substrate, wherein (a) is an external perspective view, and (B) is a sectional view.

Fig. 14 is a view showing a protective element according to a reference example in which a locking piece provided in a cover member is locked to an insulating substrate, wherein (a) is an external perspective view, (B) is a sectional view, and (C) is a bottom view.

Fig. 15 is a circuit diagram showing an example of a battery pack to which a protection element is applied.

Fig. 16 is a circuit diagram of the protection element.

Fig. 17 is a view showing a conventional protective element, wherein (a) is a plan view showing the cover member omitted, and (B) is a sectional view.

Fig. 18 is an external perspective view showing a conventional protective element.

Fig. 19 is an external perspective view showing a process of resin-sealing an open-type protective element after the protective element is mounted.

Fig. 20 is an external perspective view showing a state of interference with other members attached around the protection element.

Fig. 21 is an external perspective view showing a step of applying a sealing resin to each circuit board.

Detailed Description

Hereinafter, a protection element, a circuit module, and a method for manufacturing a protection element to which the present technology is applied will be described in detail with reference to the drawings. It is to be understood that the present technology is not limited to the following embodiments, and various changes may be made without departing from the scope of the present technology. The drawings are schematic, and the scale of each dimension and the like may be different from those in reality. Specific dimensions and the like should be determined with reference to the following description. It should be noted that the drawings also include portions having different dimensional relationships and ratios from each other.

As shown in fig. 1 and 2, a circuit module 3 to which the present invention is applied has a protective element 1 mounted on a surface of a circuit board 2. The circuit board 2 is formed with, for example, a protection circuit of the lithium ion secondary battery, and the protection element 1 is mounted on the surface thereof, so that the soluble conductor 13 is incorporated in the charge/discharge path of the lithium ion secondary battery. In the circuit module 3, when a large current exceeding the rated value of the protection element 1 flows, the fusible conductor 13 is fused by self-heating (joule heat), and the current path is interrupted. The circuit module 3 can cut off the current path by supplying current to the heating element 14 at a predetermined timing by a current control element provided on the circuit board 2 or the like, and fusing the soluble conductor 13 by heat generation of the heating element 14.

Fig. 1 is an external perspective view showing a protective element 1 to which the present invention is applied, fig. 2 is a sectional view showing a part of a circuit module 3 in which the protective element 1 is mounted on a circuit board 2, fig. 3 is a plan view showing a surface 10a of an insulating substrate 10 of the protective element 1 with a cover member 20 omitted, and fig. 4 is an external perspective view showing a back surface side of the protective element 1.

[ protective element ]

As shown in fig. 2 to 5, the protection element 1 includes: an insulating substrate 10; a heating element 14 laminated on the insulating substrate 10 and covered with an insulating member 15; a 1 st electrode 11 and a 2 nd electrode 12 formed at both ends of the insulating substrate 10; a heating element extraction electrode 16 laminated on the insulating member 15 so as to overlap the heating element 14; and a fusible conductor 13 having both ends connected to the 1 st and 2 nd electrodes 11 and 12, respectively, and a central portion connected to the heating element-drawing electrode 16.

The insulating substrate 10 is formed in a substantially rectangular shape by an insulating member such as alumina, glass ceramic, mullite, or zirconia. The insulating substrate 10 may be made of a material for a printed wiring board such as an epoxy glass substrate or a phenol resin substrate.

[ 1 st and 2 nd electrodes ]

The 1 st and 2 nd electrodes 11 and 12 are arranged on the front surface 10a of the insulating substrate 10 so as to be separated from each other in the vicinity of the side edges facing each other, and are electrically connected to each other through fusible conductors 13 by mounting fusible conductors 13 described later. Further, when a large current exceeding a rated value flows through the protective element 1, the first and second electrodes 11 and 12 are cut off by fusing the soluble conductor 13 by self-heating (joule heat) or fusing the soluble conductor 13 by heat generation of the heating element 14 due to energization.

As shown in fig. 2, the 1 st and 2 nd electrodes 11 and 12 are connected to external connection electrodes 11a and 12a provided on the rear surface 10f via an irregular mechanism (trapping) provided on the 1 st and 2 nd side surfaces 10b and 10c of the insulating substrate 10, respectively. The protection element 1 is connected to the circuit board 2 on which an external circuit is formed via the external connection electrodes 11a and 12a, and constitutes a part of a current-carrying path of the external circuit.

The 1 st and 2 nd electrodes 11 and 12 can be formed using a general electrode material such as Cu or Ag. Further, it is preferable that the surfaces of the 1 st and 2 nd electrodes 11 and 12 are plated with a coating such as an Ni/Au plating layer, an Ni/Pd plating layer, or an Ni/Pd/Au plating layer by a known method such as plating treatment. Thus, the protection element 1 can prevent oxidation of the 1 st and 2 nd electrodes 11 and 12 and prevent a variation in the rated value accompanying an increase in the on-resistance. In addition, when the protection device 1 is reflow-mounted, it is possible to prevent the connecting solder for connecting the fusible conductor 13 or the low melting point metal forming the outer layer of the fusible conductor 13 from melting and corroding (solder-corroding) the 1 st and 2 nd electrodes 11 and 12.

[ heating element ]

The heating element 14 is a conductive member that generates heat when energized, and is made of, for example, W, Mo, Ru, Cu, Ag, or an alloy containing these as main components. The heating element 14 can be formed by mixing a powder of these alloys, compositions, or compounds with a resin binder or the like, forming a paste, patterning the paste on the insulating substrate 10 by a screen printing technique, and sintering the paste. Further, the heating element 14 has one end connected to the 1 st heating element electrode 18 and the other end connected to the 2 nd heating element electrode 19.

The protection element 1 is provided with an insulating member 15 so as to cover the heating element 14, and a heating element extraction electrode 16 is formed so as to face the heating element 14 through the insulating member 15. In order to efficiently transfer the heat of the heating element 14 to the soluble conductor 13, an insulating member 15 may be laminated between the heating element 14 and the insulating substrate 10. As the insulating member 15, for example, glass can be used.

One end of the heating element-drawing electrode 16 is connected to the 1 st heating element electrode 18 and is continuous with one end of the heating element 14 via the 1 st heating element electrode 18. Further, the 1 st heating element electrode 18 is formed on the 3 rd side surface 10d side of the insulating substrate 10, and the 2 nd heating element electrode 19 is formed on the 4 th side surface 10e side of the insulating substrate 10. The 2 nd heating element electrode 19 is connected to the external connection electrode 19a formed on the rear surface 10f of the insulating substrate 10 via a concave-convex mechanism formed on the 4 th side surface 10 e.

The protection element 1 is mounted on the circuit board 2, and the heating element 14 is connected to an external circuit formed on the circuit board 2 via the external connection electrode 19a and the 2 nd heating element electrode 19. The heating element 14 is energized via the external connection electrode 19a and the 2 nd heating element electrode 19 at a predetermined timing to interrupt the energization path of the external circuit to generate heat, and the fusible conductor 13 connected to the 1 st and 2 nd electrodes 11 and 12 can be fused. Further, the soluble conductor 13 is fused, and the current path of the heating element 14 itself is also cut off, so that the heat generation is stopped.

[ fusible conductor ]

The soluble conductor 13 is made of a material that is rapidly melted by heat generated by the heating element 14, and a low-melting metal such as solder or lead-free solder containing Sn as a main component can be suitably used.

The soluble conductor 13 may be made of a high-melting metal such as In, Pb, Ag, Cu, or an alloy containing any of these as a main component, or may be a laminate of a low-melting metal and a high-melting metal. By including the high melting point metal and the low melting point metal, even when the low melting point metal is melted at a reflow temperature exceeding the melting temperature of the low melting point metal in the case of reflow mounting of the protection element 1, the low melting point metal is suppressed from flowing out to the outside, and the shape of the soluble conductor 13 is maintained. In addition, even when melting, the low melting point metal melts and the high melting point metal is melted (solder erosion), and thus the high melting point metal can be melted quickly at a temperature equal to or lower than the melting point of the high melting point metal.

The soluble conductor 13 is connected to the heating element-drawing electrode 16 and the 1 st and 2 nd electrodes 11 and 12 by solder or the like. The fusible conductor 13 can be easily connected by reflow soldering.

In addition, the soluble conductor 13 is preferably coated with flux 17 for the purpose of preventing oxidation, improving wettability, and the like.

[ cover Member ]

In the protection element 1, a cover member 20 is provided on the surface 10a of the insulating substrate 10 to protect the inside. The cover member 20 is formed in a substantially rectangular shape corresponding to the shape of the insulating substrate 10. As shown in fig. 1, the cover member 20 has a side surface 21 connected to the surface 10a of the insulating substrate 10 on which the soluble conductor 13 is provided, and a top surface 22 covering the surface 10a of the insulating substrate 10, and has an internal space 25 on the surface 10a of the insulating substrate 10 sufficient for the soluble conductor 13 to expand in a spherical shape when melted and for the melted conductor to aggregate on the heating element-drawing electrode 16 or the 1 st and 2 nd electrodes 11 and 12.

The side surface 21 of the cover member 20 is connected to the surface 10a of the insulating substrate 10 via an adhesive 26 or the like. As the adhesive 26 for connecting the lid member 20, a thermosetting adhesive having excellent connection reliability can be suitably used.

[ Vent hole ]

As shown in fig. 1 and 2, the lid member 20 is provided with a vent hole 23 penetrating into the lid member 20, and the inside of the vent hole 23 is sealed by a sealing member 24. The vent hole 23 is opened, for example, in the top surface 22 of the lid member 20. The vent hole 23 is formed by a partition wall 27 that partitions the side surface 21 of the lid member 20 and the internal space 25 in which the soluble conductor 13 is disposed. The partition wall 27 is formed downward from the top surface 22 of the cover member 20 to a height that creates a few gaps with the surface 10a of the insulating substrate 10 when the cover member 20 is attached to the surface 10a of the insulating substrate 10. That is, the vent hole 23 is continuous with the internal space 25 via the gap between the partition wall 27 and the insulating substrate 10, so that the inflation gas generated in the internal space 25 can be released to the outside when the cover member 20 is attached or the like. The vent hole 23 is sealed by a sealing member 24 after the lid member 20 is attached. The manufacturing process of the protective element 1 will be described in detail later.

By providing the vent hole 23 and sealing the vent hole 23 with the sealing member 24, the protective element 1 prevents the sealing resin applied to the circuit board 2 or the cleaning liquid of the circuit board 2 from entering the element through the vent hole 23 and filling the internal space for melting and flowing the soluble conductor 13 or removing the flux 17, and can maintain a proper blocking function as the protective element. In the protective element 1, since the inside of the vent hole 23 is sealed by the sealing member 24, the connection strength between the cover member 20 and the insulating substrate 10 can be improved, and even when the internal pressure of the element is increased by the expansion of air in the element when the circuit substrate 2 is mounted by reflow or when the fusible conductor 13 is blown, the cover member 20 can be prevented from being peeled off or damaged from the insulating substrate 10.

The vent hole 23 is formed along the 1 st and 2 nd side surfaces 10b and 10c at a position not interfering with the heating element 14 or the fusible conductor 13 in the element, for example, above the 1 st and 2 nd electrodes 11 and 12 as shown in fig. 2. The vent hole 23 may be provided above the 1 st and 2 nd heating element electrodes 18 and 19, or may extend over any of the 1 st to 4 th side surfaces 10b, 10c, 10d and 10e and be continuous, in addition to the one shown in FIG. 2. Alternatively, the vent hole 23 may be formed in the side surface 21 of the cover member 20, or may be formed so as to penetrate from the front surface 10a to the rear surface 10f of the insulating substrate 10. Further, the vent hole 23 may be formed in one or more of the top surface 22, the side surface 21, and the insulating substrate 10 of the protective element 1. The following description will be made by taking as an example a case where the vent hole 23 is formed in the top surface 22 of the lid member 20.

[ sealing Member ]

For the sealing member 24 for sealing the vent hole 23, for example, a thermosetting resin 24a is suitably used. Specific examples of the thermosetting resin 24a include thermosetting resins (e.g., SX720B, made by CEMEDINE). A sealing sheet (manufactured by KYOCERA CHEMICAL CORPORATION: TMS-701) or the like can be used as the thermosetting resin 24 a. Further, as the resin material, for example, a polyamide-based resin adhesive (OM 678, manufactured by HENKEL Co., Ltd.) can be used. The thermosetting resin 24a may be in any form such as a liquid state or a sheet state as long as it can prevent a resin material or a cleaning liquid used in a mounting step described later from flowing into the internal space 25 and has a viscosity and a strength capable of maintaining the connection between the lid member 20 and the insulating substrate 10 even when the gas inside the device expands and the internal pressure increases.

The thermosetting adhesive 24a is supplied into the vent hole 23, filled after the cover member 20 is bonded to the insulating substrate 10, heated to a predetermined temperature at the time of reflow mounting or the like, and cured.

Here, the glass transition temperature of the thermosetting resin 24a is preferably lower than the reflow temperature when the protection device 1 is reflow-mounted on the circuit board 2. Accordingly, in the protective device 1, since the thermosetting resin 24a is first cured in the mounting step on the circuit board 2, even when the gas in the internal space 25 expands and the internal pressure increases, the cap member 20 can be prevented from coming off the surface 10a of the insulating substrate 10.

The glass transition temperature of the thermosetting resin 24a is preferably 100 ℃. This can reliably cure and seal the vent hole 23 in the reflow step, and can improve the connection strength of the cover member 20 to the insulating substrate 10.

Although the sealing member 24 is described by taking the thermosetting resin 24a as an example, the present technology is not limited to this, and a photocurable resin such as an ultraviolet-curable adhesive may be used. After the cover member 20 is bonded to the insulating substrate 10, the photocurable adhesive is supplied into the vent hole 23, filled therein, and cured by being irradiated with light of a predetermined wavelength such as ultraviolet light.

[ production Process ]

Next, a manufacturing process of the protection element 1 will be described with reference to fig. 5. As shown in FIG. 5A, first, the 1 st and 2 nd electrodes 11 and 12, the heating element 14, the 1 st and 2 nd heating element electrodes 18 and 19, the insulating member 15, and the heating element-drawing electrode 16 are formed on the surface 10a of the insulating substrate 10. The external connection electrodes 11a, 12a, and 19a are formed on the rear surface 10f of the insulating substrate 10, and are connected to the 1 st and 2 nd electrodes 11 and 12 and the 2 nd heating element electrode 19 via a concave-convex mechanism. The soluble conductor 13 is mounted across the 1 st and 2 nd electrodes 11 and 12 with the heating element-drawing electrode 16 interposed therebetween. Further, the connecting solder may be supplied between the soluble conductor 13 and the 1 st and 2 nd electrodes 11 and 12 and the heating element-drawing electrode 16.

Next, as shown in fig. 5 (B), the cover member 20 is attached to the surface 10a of the insulating substrate 10. The lid member 20 is preferably connected by supplying a thermosetting adhesive 26 having excellent connection strength to the lower portion of the side surface 21. The cover member 20 is mounted on the structure 28 on the front surface 10a of the insulating substrate 10, and secures the internal space 25 divided by the partition wall 27 around the soluble conductor 13.

Next, the structure 28 having the lid member 20 mounted on the surface 10a of the insulating substrate 10 is subjected to a heat treatment, so that the soluble conductors 13 are connected to the 1 st and 2 nd electrodes 11 and 12 and the heating element lead-out electrodes 16 via connecting solders, and the lid member 20 is connected to the surface 10a of the insulating substrate 10 by curing the thermosetting adhesive 26.

At this time, since the inflation gas in the internal space 25 is discharged to the outside through the vent hole 23 provided in the cover member 20, the internal pressure of the cover member 20 does not increase even during curing of the adhesive 26, and connection to the surface 10a of the insulating substrate 10 is not hindered.

Next, as shown in fig. 5 (C), the sealing member 24 is supplied to the vent hole 23 and sealed, thereby forming the protection element 1. The protection element 1 is mounted on a circuit board 2 on which a power supply circuit and the like are formed by reflow or the like, thereby forming a circuit module 3.

When the thermosetting resin 24a is used as the sealing member 24, the protective element 1 may be subjected to a heat treatment to cure the thermosetting resin 24a, but the thermosetting resin 24a may be cured by heating at the time of reflow mounting of the circuit board 2. At this time, since the thermosetting resin 24a is cured first by using the thermosetting resin 24a having a glass transition temperature lower than the reflow temperature as the thermosetting resin 24a, the connection strength of the lid member 20 is improved, and even when the gas in the internal space 25 expands and the internal pressure increases, the lid member 20 can be prevented from falling off from the surface 10a of the insulating substrate 10.

When a photocurable resin is used as the sealing member 24, it is preferable that the resin be cured by irradiation with ultraviolet light after filling the vent holes 23 and before reflow mounting to the circuit board 2.

[ modification 1]

Next, a modified example of the present technology will be described. In the following description of the modifications, the same members as those of the protection element 1 and the circuit module 3 are denoted by the same reference numerals, and the details thereof are omitted.

As shown in fig. 6, the vent hole 23 may be provided with a protrusion 31 protruding into the vent hole on the inner side surface. In the protective element 1, the protrusion 31 is provided on the inner surface of the vent hole 23, and when the thermosetting resin 24a or the photocurable resin is filled as the sealing member 24, the contact area in the vent hole 23 is increased, whereby the connection strength of the cover member 20 can be further improved.

As shown in fig. 6, the protrusion 31 may be formed on the partition wall 27, on the side surface 21, or on both the partition wall 27 and the side surface 21. One or more projections 31 may be formed along the direction of ventilation to the top surface 22, and the projections 31 formed in plural may have the same projection height or different projection heights. The protruding portion 31 may be formed continuously or intermittently in the circumferential direction of the cover member 20.

As shown in fig. 6, when the vent hole 23 is provided in the top surface 22, the protrusion 31 protrudes above the surface 10a of the insulating substrate 10, and therefore the thermosetting resin 24a or the photocurable resin filled in the vent hole 23 acts as an anchor bolt for the protrusion 31, and the lid member 20 can be made more difficult to fall off from the insulating substrate 10.

As shown in fig. 7, a vent hole 23 may be provided from the top surface 22 to the insulating substrate 10, a protrusion 31 protruding into the vent hole 23 may be provided, and a 2 nd protrusion 31a protruding toward the insulating substrate 10 side may be formed further than the protrusion 31. The 2 nd protrusion 31a is formed to protrude toward the insulating substrate 10 side, so that the connection strength of the cover member 20 with respect to the direction parallel to the insulating substrate 10 can be improved. That is, the protruding portion 31 protrudes above the surface 10a of the insulating substrate 10, thereby increasing the strength of the cover member 20 in the direction perpendicular to the insulating substrate 10, whereas the 2 nd protruding portion 31a protruding toward the surface 10a of the insulating substrate 10 increases the strength of the cover member 20 in the direction parallel to the insulating substrate 10.

One or more 2 nd protrusions 31a may be formed, and the 2 nd protrusions 31a formed in plural may have the same protrusion height or different protrusion heights, respectively. The 2 nd projecting portion 31a may be formed continuously or intermittently in the circumferential direction of the lid member 20. The more the 2 nd protrusion 31a is formed, the more the strength of the cover member 20 with respect to the direction parallel to the insulating substrate 10 increases.

The protruding portion 31 also includes a form in which a recess is formed in the inner surface of the partition wall 27 or the side surface 21, and the inner surface of the partition wall 27 or the side surface 21 is formed to protrude relatively to the recess. The protruding portion 31 also includes a form formed by so-called surface texturing, roughening, embossing, or the like.

Similarly, the 2 nd projecting portion 31a is formed by forming a recess in the projecting portion 31 facing the insulating substrate 10 and projecting the projecting portion 31 toward the insulating substrate 10 side. The 2 nd projecting portion 31a also includes a form formed by so-called surface texturing, roughening, embossing, or the like.

[ modification 2]

As shown in fig. 8, the vent hole 23 may be formed with a tapered portion 32 whose inner surface is tapered in the vent direction in a cross-sectional view. In the protective element 1, the tapered portion 32 is formed on the inner surface of the vent hole 23, and thus when the thermosetting resin 24a or the photocurable resin is filled as the sealing member 24, the contact area in the vent hole 23 is increased, and the connection strength of the lid member 20 can be further improved.

As shown in fig. 8, the tapered portion 32 may be formed on the partition wall 27, on the side surface 21, or on both the partition wall 27 and the side surface 21. The tapered portion 32 may be configured to expand in diameter in the direction of ventilation toward the top surface 22, or may be configured to reduce in diameter, but as shown in fig. 8, the tapered portion 32 is preferably configured to expand in diameter in the direction of ventilation toward the top surface 22, so that the thermosetting resin 24a or the photocurable resin filled in the vent hole 23 acts as an anchor to the tapered portion 32, and the cover member 20 can be made more difficult to fall off from the insulating substrate 10.

The above-described protrusion 31 or the 2 nd protrusion 31a may be formed on the tapered portion 32. The tapered portion 32 is formed in a curved surface shape or a stepped shape and is expanded or reduced in diameter along the ventilation direction.

[ modification 3]

As shown in fig. 9, the protective element 1 may be configured such that a partition wall member 33 forming the internal space 25 is disposed inside the cover member 20, and a thermosetting resin 24a or a photocurable resin is filled between the top surface 22 of the cover member 20 and the partition wall member 33.

The partition member 33 is formed in a substantially box shape having one open surface, similarly to the cover member 20, and includes a partition side surface 33a constituting the vent hole 23 and a partition top surface 33b opposed to the top surface 22 of the cover member 20. The partition member 33 is disposed on the surface 10a of the insulating substrate 10 to form the internal space 25. The partition member 33 has a gap formed between the lower portion of the partition side surface 33a on the side facing the vent hole 23 and the surface 10a of the insulating substrate 10, and the internal space 25 and the vent hole 23 are continuous. The partition wall member 33 is fixed by adhering to the surface 10a of the insulating substrate 10a, the partition wall side surface 33a not facing the vent hole 23.

The protective element 1 is provided with the partition wall member 33 so as to secure the internal space 25 in which the soluble conductor 13 melts and flows, and the lid member 20 is disposed from above the partition wall member 33. This forms the vent hole 23 with the partition wall member 33, and fills the sealing member 24 such as the thermosetting resin 24a, thereby improving the connection strength between the cover member 20 and the partition wall member 33 to the insulating substrate 10. Further, by filling the space between the partition wall top surface 34b and the top surface 22 of the cover member 20 with the sealing resin, the filling amount can be increased, and the connection strength between the cover member 20 and the partition wall member 33 to the insulating substrate 10 can be further improved.

The partition member 33 may be a member different from the cover member 20, but may be integrally molded with the cover member 20.

[ reference example 1]

Now, a structure of the protective element package 37 according to a reference example of the present technology will be described with reference to fig. 10. The protective element 35 shown in fig. 10 is mounted with only the partition member 33 described above on the surface 10a of the insulating substrate 10. The protection element 35 is further mounted on an interposer (interposer) substrate 36, and the cover member 20 is mounted on the interposer substrate 36 and sealed, thereby forming a protection element package 37. The interposer substrate 36 includes connection electrodes 37a connected to the 1 st and 2 nd external connection electrodes 11a and 12a and the external connection electrodes connected to the heating element electrodes 19, and is mounted on the circuit substrate 2 not shown by reflow mounting or the like. The cover member 20 is connected to the interposer substrate 36 with a thermosetting adhesive or the like having excellent connection reliability or with ultrasonic welding or the like.

Since the lid member 20 of the protective element package 37 covers the entire protective element 35 and has a large internal space constituting the package exterior, the internal pressure rises slightly even when the gas inside the element expands, such as when the fusible conductor 13 is reflow-mounted or blown, and the internal pressure has sufficient resistance. Therefore, the protective element package 37 can prevent a connection failure or breakage of the cover member 20 due to an increase in the internal pressure of the protective element 35.

[ modification 4]

As shown in fig. 11, the protective element 1 may be formed by using a sealing member 24 in which a thermosetting resin 24a, a photocurable resin, or the like is filled on the partition top surface 33b of the partition member 33 without providing the cover member 38 having the partition member 33 and the top surface 22. In the protective element 1 shown in fig. 11, since the side surface 21 of the cover member 38 and the partition side surface 33a of the partition member 33 and the upper surface of the partition top surface 33b are fixed by resin, the connection strength of the cover member 38 and the partition member 33 to the insulating substrate 10 can be improved.

The partition member 33 may be a member different from the cover member 38, but may be integrally molded with the cover member 38.

[ modification 5]

As shown in fig. 12, in the protective element 1, as the sealing member 24 for sealing the vent hole 23, a fitting pin 24b fitted into the vent hole 23 may be used in addition to an adhesive such as a thermosetting resin 24 a. The protection element 1 shown in fig. 12 is provided with a snap step portion 39 that snaps the fitting pin 24b in the ventilation hole 23. The vent hole 23 is formed in a cylindrical shape corresponding to the shape of the fitting pin 24 b. A plurality of vent holes 23 may be formed along the 1 st and 2 nd side surfaces 10b and 10c above the 1 st and 2 nd electrodes 11 and 12. The vent hole 23 may be provided above the 1 st and 2 nd heating element electrodes 18 and 19, in addition to those shown in FIG. 12.

In the protective element 1, the fitting pin 24b fitted into the vent hole 23 is used as the sealing member 24 in addition to the adhesive such as the thermosetting resin 24a, whereby the vent hole 23 can be more reliably sealed and the connection strength of the lid member 20 can be improved.

The fitting pin 24b may be, for example, pressed into the vent hole 23, in addition to being caught by the catch step 39. In this case, the vent hole 23 may be formed in a tapered shape having a diameter increased toward the top surface 22, and similarly, the fitting pin 24b may be formed in a tapered shape having a diameter decreased toward the tip. Alternatively, the vent hole 23 and the fitting pin 24b may be screwed together by forming a screw groove. In addition, the vent hole 23 and the fitting pin 24b may have a guide convex portion formed on one side and a guide concave portion formed on the other side so that the guide convex portion slides in the insertion direction of the fitting pin 24 b.

[ modification 6]

As shown in fig. 13, in the protection element 1, only the fitting pin 24b may be used as the sealing member 24 for sealing the vent hole 23. In this case, the fitting pin 24b is connected to the insulating substrate 10, which is preferable in improving the connection strength of the cover member 20. For example, the fitting pins 24b form screw grooves and are screwed into screw holes provided in the surface 10a of the insulating substrate 10, so that the cover member 20 can be screwed to the insulating substrate 10. In addition, the fitting pin 24b may be formed with a sharp distal end and inserted through the surface 10a of the insulating substrate 10 to be connected.

In the configuration shown in fig. 13, the fitting pin 24b may be, for example, press-fitted into the vent hole 23, in addition to being caught by the catch step 39. In this case, the vent hole 23 may be formed in a tapered shape having a diameter increased toward the top surface 22, and similarly, the fitting pin 24b may be formed in a tapered shape having a diameter decreased toward the tip. Alternatively, the vent hole 23 and the fitting pin 24b may be screwed together by forming a screw groove. In addition, the vent hole 23 and the fitting pin 24b may have a guide convex portion formed on one side and a guide concave portion formed on the other side so that the guide convex portion slides in the insertion direction of the fitting pin 24 b.

[ reference example 2]

Now, the structure of the protective element package 37 according to the reference example of the present technology will be described with reference to fig. 14. In the protective element 40 shown in fig. 14 (a) to (C), a latch piece 42a formed on a side surface 42 of the cover member 41 is latched to the rear surface 10f of the insulating substrate 10. The cover member 41 has an inner dimension substantially equal to that of the insulating substrate 10, and a pair of side surfaces 42 facing each other are formed with snap pieces 42a to be snapped to the back surface 10f of the insulating substrate 10.

The cover member 41 is fitted from the front surface 10a side of the insulating substrate 10, and the locking piece 42a is locked to the rear surface 10f of the insulating substrate 10, thereby constituting the device package. In the protection element 40, the cover member 41 is fitted into the insulating substrate 10, whereby the internal space 25 in which the soluble conductor 13 melts and flows is formed between the top surface 43 and the surface 10a of the insulating substrate 10.

Since the protective element 40 is firmly connected between the cover member 41 and the insulating substrate 10 by the snap piece 42a being snapped to the back surface 10f of the insulating substrate 10, it has sufficient resistance to an increase in internal pressure even when the gas inside the element expands, for example, when the fusible conductor 13 is reflow-mounted or fused. Therefore, the protective element 40 can prevent a connection failure or breakage of the cover member 41 due to an increase in internal pressure.

[ Circuit Board ]

Next, the circuit board 2 on which the protection element 1 is mounted will be described. The circuit board 2 is a rigid substrate such as an epoxy glass substrate, a glass substrate, or a ceramic substrate, or a known insulating substrate such as a flexible substrate. As shown in fig. 1 and 2, the circuit board 2 has a mounting portion on which the protection element 1 is surface-mounted by reflow or the like, and connection electrodes connected to the external connection electrodes 11a and 12a provided on the rear surface 10f of the insulating substrate 10 of the protection element 1 and the external connection electrode 19a connected to the 2 nd heating element electrode 19 are provided in the mounting portion. Further, an element such as an FET for supplying power to the heating element 14 of the protection element 1 is mounted on the circuit board 2.

[ method of Using Circuit Module ]

Next, a method of using the protection element 1 and the circuit module 3 having the protection element 1 mounted on the surface of the circuit board 2 will be described. As shown in fig. 15, the circuit module 3 is used as a circuit in a battery pack of a lithium ion secondary battery, for example.

For example, the protection element 1 is incorporated into a battery pack 50 having a battery stack 55 composed of battery cells 51 to 54 of 4 lithium ion secondary batteries in total.

The battery pack 50 includes: a battery stack 55; a charge/discharge control circuit 60 for controlling charge/discharge of the battery stack 55; the protection element 1 to which the present invention is applied, which interrupts charging when the battery stack 55 is abnormal; a detection circuit 56 for detecting the voltage of each of the battery cells 51 to 54; and a current control element 57 for controlling the operation of the protection element 1 in accordance with the detection result of the detection circuit 56.

The battery stack 55 is connected in series with battery cells 51 to 54 that need to be controlled for protection in an overcharged or overdischarged state, is detachably connected to a charging device 65 via a positive electrode terminal 50a and a negative electrode terminal 50b of the battery pack 50, and is applied with a charging voltage from the charging device 65. The positive electrode terminal 50a and the negative electrode terminal 50b of the battery pack 50 charged by the charging device 65 are connected to an electronic device operated by a battery, and the electronic device can be operated.

The charge/discharge control circuit 60 includes: two current control elements 61, 62 connected in series in a current path flowing from the battery stack 55 to the charging device 65; and a control unit 63 for controlling the operation of the current control elements 61 and 62. The current control elements 61 and 62 are formed of, for example, field effect transistors (hereinafter, referred to as FETs), and control the on/off of the current path of the cell stack 55 by controlling the gate voltage by the control unit 63. The control unit 63 operates upon receiving power supply from the charging device 65, and controls the operation of the current control elements 61 and 62 so as to block the current path when the battery stack 55 is over-discharged or over-charged in accordance with the detection result of the detection circuit 56.

The protection element 1 is connected to a charge/discharge current path between the battery stack 55 and the charge/discharge control circuit 60, for example, and its operation is controlled by the current control element 57.

The detection circuit 56 is connected to each of the battery cells 51 to 54, detects the voltage value of each of the battery cells 51 to 54, and supplies each voltage value to the control unit 63 of the charge/discharge control circuit 60. The detection circuit 56 outputs a control signal for controlling the current control element 57 when any of the battery cells 51 to 54 becomes an overcharge voltage or an overdischarge voltage.

The current control element 57 is formed of, for example, an FET, and controls the protection element 1 to operate so as to interrupt the charge/discharge current path of the battery stack 55 regardless of the switching operation of the current control elements 61 and 62 when the voltage values of the battery cells 51 to 54 become a voltage exceeding a predetermined over-discharge or over-charge state based on the detection signal output from the detection circuit 56.

In the battery pack 50 having the above-described structure, the structure of the protection element 1 will be specifically described.

First, the protection element 1 to which the present invention is applied has a circuit configuration shown in fig. 16. That is, the protection element 1 has a circuit configuration including the soluble conductor 13 connected in series via the heating element lead-out electrode 16, and the heating element 14 that generates heat by being energized via the connection point of the soluble conductor 13 to melt the soluble conductor 13. In the protective element 1, for example, the soluble conductor 13 is connected in series to the charge/discharge current path, and the heating element 14 is connected to the current control element 57. The 1 st electrode 11 of the protection element 1 is connected to the open end of the cell stack 55 via the external connection electrode 11a, and the 2 nd electrode 12 is connected to the open end of the battery 50 on the positive electrode terminal 50a side via the external connection electrode 12 a. The heating element 14 is connected to the soluble conductor 13 via the heating element extraction electrode 16, and is connected to the charge/discharge current path of the battery pack 50, and is connected to the current control element 57 via the 2 nd heating element electrode 19 and the external connection electrode.

When the heating element 14 of the protective element 1 is energized and generates heat, the fusible conductor 13 melts and is attracted to the heating element extraction electrode 16 due to its wettability. As a result, the protection element 1 can reliably block the current path by the fusing of the fusible conductor 13. Further, the fusible conductor 13 is fused, and the power supply path to the heating element 14 is also cut off, so that the heating element 14 also stops generating heat.

In addition, in the battery pack 50, when an unexpected large current exceeding the rating of the protection element 1 flows through the charge/discharge path, the fusible conductor 13 is fused by self-heating (joule heat), and the current path can be blocked.

As described above, since the protection element 1 seals the inside of the vent hole 23 with the sealing member 24, even when the internal pressure of the element is increased by the expansion of air when the circuit board 2 is mounted by reflow or when the fusible conductor 13 is blown, the connection strength between the cover member 20 and the insulating substrate 10 can be improved, and the cover member 20 can be prevented from being peeled off or damaged from the insulating substrate 10.

The protection element 1 to which the present technology is applied is not limited to the case of a battery pack used for a lithium ion secondary battery, and may be obviously applied to various applications requiring the interruption of a current path by an electric signal. The protection element 1 to which the present technology is applied may be a fuse element that is configured to perform only self-heating cutoff at the time of overcurrent without including the heating element 14.

Description of the reference symbols

1a protective element; 2a circuit board; 3a circuit module; 10 an insulating substrate; 11 the 1 st electrode; 12a 2 nd electrode; 13 a fusible conductor; 14 a heating element; 15 an insulating member; 16 heating element lead-out electrodes; 17 a flux; 18 the 1 st heating element electrode; 19 the 2 nd heater electrode; 20 a cover member; 21 side surface; 22 a top surface; 23 vent holes; 24a sealing member; 24a thermosetting resin; 24b a snap pin; 25 an inner space; 26 an adhesive; 27 a partition wall; 28 a structure; 31a projection; 32 a taper portion; 33a bulkhead member; 33a bulkhead side; 33b top surfaces of the partition walls; 35 a protective element; 36 inserting the substrate; 37 protecting the component package; 38 a cover member; 39 a snap step; 40 a protective element; 41 a cover member; 42 side surface; 42a snap tab; 43 a top surface; 50 battery packs; 51-54 battery cells; 55, stacking the batteries; 56 a detection circuit; 57 a current control element; 60 a charge and discharge control circuit; 61 a current control element; 62 a current control element; 63 a control unit; 65 charging means.

Claims (11)

1. A protection element is provided with:

an insulating substrate;

1 st and 2 nd electrodes provided on the insulating substrate;

a soluble conductor disposed across the 1 st and 2 nd electrodes; and

a cover member disposed on the side of the insulating substrate on which the soluble conductor is disposed,

a vent hole for making the internal space equipped with the fusible conductor touch the outside of the element is arranged,

the above vent hole is sealed by a sealing member before the protective element is mounted on the circuit substrate by reflow,

the sealing member is a resin having a glass transition temperature lower than a reflow temperature of the reflow mounting.

2. The protective element according to claim 1, wherein the glass transition temperature of the resin is 100 ℃ or higher.

3. The protective element according to claim 1, wherein the sealing member is a fitting member that is fitted to the vent hole.

4. A protective member according to any one of claims 1 to 3 wherein said vent is provided in said cover member.

5. The protective member according to claim 4, wherein the vent hole is provided at an inner side surface thereof with a protrusion protruding toward an inside of the vent hole.

6. The protective member according to claim 4, wherein the vent hole is provided with a tapered portion whose inner side surface is formed in a tapered shape as viewed in cross section.

7. The protective element according to claim 2, wherein a partition member forming the internal space is provided inside the cover member, and the resin is filled between the cover member and the partition member.

8. The protective element according to claim 7, wherein the resin is filled between a top surface of the cover member and a top surface of the partition member.

9. The protective element of claim 7,

with the cover member not provided with the top surface,

the resin is filled on the top surface of the partition wall member.

10. A circuit module having:

a protective element; and

a circuit board having the protective element mounted on the surface thereof,

the protection element includes:

an insulating substrate;

1 st and 2 nd electrodes provided on the insulating substrate;

a soluble conductor disposed across the 1 st and 2 nd electrodes; and

a cover member disposed on the side of the insulating substrate on which the soluble conductor is disposed,

a vent hole for making the internal space equipped with the fusible conductor touch the outside of the element is arranged,

the vent hole is sealed by a sealing member before the protective element is mounted on the circuit board by reflow,

the sealing member is a resin having a glass transition temperature lower than a reflow temperature of the reflow mounting.

11. A method for manufacturing a protective element, wherein,

forming a 1 st electrode and a 2 nd electrode on an insulating substrate, and disposing a soluble conductor across the 1 st electrode and the 2 nd electrode;

forming a structure having a vent hole for allowing the internal space in which the soluble conductor is disposed to hit the outside of the device on the insulating substrate with a thermosetting resin mounting cover member interposed therebetween;

connecting the cover member to the insulating substrate by heating the structure;

the ventilation hole is sealed with a sealing member before the protection element is mounted on the circuit board by reflow,

the sealing member is a resin having a glass transition temperature lower than a reflow temperature of the reflow mounting.

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