JP4841685B2 - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack having a structure in which a heat sensitive element is prevented from thermal breakage by a filled resin when the battery pack is constructed by integrating a secondary battery and a circuit board with a resin molding. <P>SOLUTION: A heat insulating sheet 16 is arranged covering a thermal fuse 10 which is installed on a sealing plate 23 of the secondary battery 2, thereby, heat of the resin that is filled between the secondary battery 2 and the circuit board 3 and becomes a primary molded body 11 is shielded by the heat insulating sheet 16, and thermal breakage of the thermal fuse 10 is prevented. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a battery pack in which constituent elements are integrated by resin filling so as to be suitable for a battery power source of a small portable electronic device or the like, thereby reducing size and improving robustness.

  Mobile electronic devices such as mobile phones and PDAs are becoming smaller and thinner, and more advanced in functionality, and accordingly, a battery serving as a power source is required to be smaller, thinner and have higher capacity. Lithium ion secondary batteries are effective as compact and high capacity batteries, and flat rectangular ones are suitable for thinning devices, and can be used repeatedly as portable batteries for portable electronic devices. Application is increasing.

  Since the lithium ion secondary battery has a high energy density and uses a flammable organic solvent as an electrolytic solution, consideration for safety is important. It is necessary to ensure safety so as not to damage the human body and equipment even when an abnormality occurs for some reason. For example, when a short circuit occurs between the positive electrode terminal and the negative electrode terminal of the battery for some reason, an excessive short circuit current flows in a battery with high energy density, Joule heat is generated due to internal resistance, and the battery temperature rises. When the battery temperature rises, the reaction between the positive electrode plate active material and the electrolyte solution, the evaporation and decomposition of the electrolyte solution, and the like, the gas pressure inside the battery increases rapidly, and the battery may burst or ignite. The cause of the battery becoming hot is not only the above external short circuit, but also when the secondary battery is overcharged, or when the portable electronic device loaded with the battery is placed near the heater or left in a car parked under hot weather And so on.

  There are various causes such as electrical, mechanical, thermal, etc. that can cause the battery to fall into an abnormal state. In non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries, the battery falls into an abnormal state. And a function for preventing a dangerous state even when an abnormal state occurs. As a function of the battery itself, the active material of the electrode plate and the electrolytic solution have been devised so as not to cause an excessive reaction, and the polyolefin microporous membrane used as a separator softens and closes the pores at an abnormally high temperature. There is a shutdown function. In addition, the cylindrical lithium ion secondary battery is provided with a protective function for limiting excessive current due to an external short circuit by providing a PTC (Positive Thermal Coefficient) element connected in series with the input / output circuit in the sealing portion. Yes. In a small battery that does not have a space for providing the PTC element in the battery, a PTC element and a thermal fuse are connected by wiring as external circuit components, and a battery protection circuit that protects the battery from overcharge and overdischarge is provided. Is an essential requirement, and these components are generally housed in a pack case together with a secondary battery and configured in the form of a battery pack.

  However, the resin molding die for forming the pack case is expensive to manufacture and has a long development period, so that it cannot be applied to portable electronic devices with a short introduction period of new models. In addition, as described above, in order to configure a battery pack corresponding to miniaturization and thinning of a portable electronic device, there is a limit to the wall thickness that can be molded by resin molding, and there is a limit to an exterior case by resin molding.

  Also, in order to ensure safety, it is necessary to disassemble the battery pack so that it is difficult to disassemble the battery pack and prevent it from being used in an incorrect or interesting manner. Is important. In consideration of application to portable electronic devices, a robust structure capable of withstanding impact and vibration due to dropping and the like and moisture resistance of electronic circuit parts are required. In order to realize such a robust and moisture-resistant structure that is difficult to disassemble, it has been envisaged that a circuit board constituting a battery protection circuit or the like and a battery are integrated by resin molding.

  The battery pack by the resin molding is disclosed in Patent Document 1 and Patent Document 2, and an intermediate finished product in which a battery and a circuit board are connected by a connecting member is arranged in a mold and formed on the circuit board. Fill the periphery of the intermediate product with resin so that the external connection terminals are exposed to the outside.

  Moreover, in patent document 3, what connected the battery and the circuit board by the connection member is arrange | positioned in a metal mold | die, the circuit board is resin-sealed, and it fixes to a battery or a pack case (battery cover), Or the structure which resin-seals a circuit board and a battery is disclosed.

JP 2002-134077 A JP 2002-166447 A JP 2000-315483 A

  As described above, a battery pack using a lithium ion secondary battery has a function of protecting the secondary battery so as not to increase in temperature due to an external short circuit or overcharge, but such a protection function did not function. In order to shut off the battery circuit as a final safety function, a battery pack is configured by providing a thermal sensitive element such as a thermal fuse or a PTC element.

  The heat-sensitive element is arranged in a state where it is thermally coupled to the secondary battery so as to operate not only by an excessive current but also by the temperature of the secondary battery, and is connected to a circuit from the secondary battery to the circuit board. When filling and molding a resin between the battery and the circuit board, it is necessary to prevent the heat-sensitive element from being thermally destroyed by the temperature of the filled resin. In the case of a thermal fuse, the temperature is generally set to blow at 104 ° C. Even if the resin to be filled is a hot melt having a relatively low melting temperature, the temperature exceeds 200 ° C. It is. Hot melt has a lower melting temperature than other molding resins and is easy to handle, but it still exceeds the fusing temperature of a thermal fuse. If this hot melt comes into direct contact with the thermal fuse, the thermal fuse will definitely melt, and the battery pack will break and the circuit will not function. Even in the case of PTC elements, the temperature of the polymer exceeding 200 ° C. changes the cross-linked state of the conductive polymer, which is the main constituent material, and changes the temperature-current characteristics and trip temperature, thereby improving the reliability of the PTC element. It will be in a state that damages. Therefore, in the battery pack that is configured by integrating the secondary battery and the circuit board by resin filling, a countermeasure is taken so as not to destroy the heat sensitive element during manufacturing. This is an essential requirement.

  The purpose of the present invention is a battery provided with a structure that is not destroyed by a resin filled with a heat sensitive element provided as a safety function when the battery and circuit board are integrated by a resin mold to form a battery pack. To provide a pack.

  In the first invention of the present application, a substrate on which external connection terminals are formed is arranged on the sealing plate side of the secondary battery with a gap, and the secondary battery and the substrate are integrated by filling and molding the resin in the gap. In the battery pack, a heat sensitive element is thermally coupled to the secondary battery in a recess formed in the sealing plate, and a heat insulating member or other component is disposed to cover the recess. It is characterized by. The thermosensitive temperature element is disposed in the recess, and the other components are disposed over the recess, so that the filled resin does not touch the thermosensitive element, and the resin is not filled during resin filling molding. The battery pack can be configured without destroying the heat-sensitive element due to the temperature. Further, when the heat sensitive element is disposed in the recess, the heat of the secondary battery is easily transferred to the heat sensitive element, and an abnormal temperature rise of the secondary battery can be detected and operated quickly.

  Further, according to the second invention of the present application, a substrate on which external connection terminals are formed with a gap is disposed on the sealing plate side of the secondary battery, and the resin filled in the gap integrates the secondary battery and the substrate. The heat-sensitive element is characterized in that a heat-sensitive element thermally coupled to the secondary battery is disposed in the gap, and the heat-sensitive element is formed with a heat-insulating coating layer. The coating layer of the heat-sensitive element has heat insulation properties, and the side on which the coating layer is formed is in contact with the molding resin so that the heat-sensitive element is exposed to a high-temperature molding resin during resin molding. It is possible to prevent the deterioration of device characteristics. With this configuration, the heat sensitive element is protected by the coating layer, and it is not necessary to cover the heat sensitive element with the heat insulating member. At the time of manufacturing, it is not necessary to arrange the heat insulating means, so that the number of man-hours is reduced and the number of parts is reduced, which is effective in terms of cost reduction. In addition, it is preferable to apply the resin material which has heat insulation for the coating layer mentioned above. On the other hand, it is necessary to thermally couple to the secondary battery, and it is preferable that a coating layer is not formed at a portion in contact with the secondary battery. Therefore, by adopting a configuration in which a coating layer is not formed only on a portion in contact with the secondary battery, it is possible to embody a heat sensitive element that is excellent in heat shielding during resin molding and detection accuracy of the secondary battery temperature. Such an element increases the number of manufacturing steps, and further complicates the process when arranging the heat sensitive element in the secondary battery. After the battery pack is constructed, by using a resin with thermal characteristics that do not decrease the detection accuracy of the secondary battery temperature, in addition to heat shielding and detection accuracy, a heat sensitive element that is excellent in production man-hours and cost Can be provided.

  In each of the above configurations, the heat-sensitive element can be configured as a thermal fuse, and when the temperature of the secondary battery rises abnormally, it is blown to shut off the battery circuit and connect to the battery circuit that causes the temperature rise. Can be cut off. In addition, PTC elements can be used as heat-sensitive elements, not only to limit the excessive current when an external short circuit occurs, but also to limit the battery circuit current by rapidly increasing the resistance value due to abnormal temperature rise of the secondary battery Therefore, the connection to the battery circuit that causes the temperature rise can be cut off. In addition, a thermosensitive element can be applied with a bimetal thermostat, which not only cuts off the current due to the temperature rise when an external short circuit occurs, but also shuts down the circuit due to the abnormal temperature rise of the secondary battery. Since the current is limited, the connection to the battery circuit that causes the battery temperature to rise can be cut off.

  According to the present invention, the substrate on which the external connection terminals are formed is disposed with a gap from the secondary battery, and the gap between the substrate and the secondary battery is formed by filling the gap with a resin to form a battery pack. In some cases, the battery pack can be provided that is firmly constructed by resin filling molding without being thermally destroyed by the resin filled in the heat sensitive element disposed in the gap.

The perspective view which shows the external appearance of the battery pack which concerns on embodiment. The disassembled perspective view which shows each component of a battery pack same as the above. (A) which shows the structure of a secondary battery, (b) is sectional drawing by the side of a sealing board, (c) is a top view in the state where the thermal fuse was attached. FIG. 3A is a perspective view showing a configuration of a circuit board, wherein FIG. 4A is an outer surface side, FIG. 5B is an inner surface side, and FIG. The perspective view which shows the attachment state to the secondary battery of a circuit board. The schematic diagram explaining the positioning method by a metal mold | die. The perspective view which shows the structure of a primary mold metal mold | die. Sectional drawing which shows the state which formed the primary mold body. The perspective view which shows the structure of a secondary mold die. Sectional drawing which shows the state which formed the secondary mold body. The perspective view which shows the formation state in each step of a manufacturing process in order. Sectional drawing explaining the formation position of a connection shaping | molding part. Sectional drawing which shows another aspect of arrangement | positioning structure of a thermal fuse.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

  The present embodiment shows an example in which a battery pack to be applied to a mobile phone is configured using a flat rectangular lithium ion secondary battery. Battery packs applied to mobile phones are compact, lightweight, thin, high energy density for high functionality, mechanical strength that can withstand impacts such as drops that are unavoidable as portable devices, structures that are difficult to disassemble, and short circuits It is required to have a safety function for protecting the secondary battery from overcharge, high temperature, etc., and the battery pack shown below is configured to satisfy these requirements.

  FIG. 1 shows an external appearance of a battery pack 1 according to the embodiment. A flat shape in which an external connection terminal 6 including a positive electrode terminal, a negative electrode terminal, and a temperature detection terminal is externally exposed on one end face and a submerged seal 9 is attached. It is configured. FIG. 2 is an exploded view of the battery pack 1 and shows each component. Details of each component and a method for manufacturing the battery pack 1 using each component will be described below.

  As shown in FIG. 3, a lithium ion secondary battery (hereinafter referred to as a secondary battery) 2 has a power generation element housed in an aluminum battery can 22 formed in a bottomed cylindrical shape having an oblong cross section. The battery can 22 is sealed by laser welding a sealing plate 23 to the opening end. The sealing plate 23 which is joined to the battery can 22 and becomes the battery positive electrode has a battery negative electrode 25 formed in a convex manner at the center thereof by insulation with the upper gasket 24a and the lower gasket 24b. In addition, mushroom-like engagement protrusions 26 and 26 are formed on both sides of the sealing plate 23 by pressing the sealing plate 23. Reference numeral 27 denotes a sealing plug for closing the electrolytic solution injection port. After the electrolytic solution is injected into the battery can 22, the electrolytic solution injection port is closed by the sealing plug 27, and the sealing plug 27 is welded to the sealing plate 23.

  The engaging protrusion 26 is formed in a mushroom shape as shown in the figure when a cylindrical protruding portion is formed at a predetermined position of the sealing plate 23 by pressing and is pressed so that its head opens to the periphery. . The engaging protrusion 26 can also be formed by welding a mushroom-shaped or inverted L-shaped member to the sealing plate 23 without using press working.

  In the secondary battery 2, as shown in FIG. 3C, one connection piece 10 a of a temperature fuse (heat sensitive element) 10 is spot welded to the battery negative electrode 25. A heat insulating sheet 16 is adhered to the upper surface of the thermal fuse 10 as shown by a broken line, and the thermal fuse 10 is prevented from being blown during resin filling described later. Here, a 0.6 mm thick VHB acrylic foam (manufactured by Sumitomo 3M) is applied as the heat insulating sheet 10 in which a pressure-sensitive adhesive layer is formed on a sheet obtained by foaming an acrylic resin. it can. The other connection piece 10b of the thermal fuse 10 is disposed on the insulating paper 21 adhered on the sealing plate 23, and a negative electrode lead plate 5 described later is connected thereto. Further, the thermal fuse 10 is fixed to the sealing plate 23 with a heat conductive adhesive, so that it is thermally coupled to the secondary battery 2.

  As shown in FIG. 4A, the circuit board 3 constituting a protection circuit that protects the secondary battery 2 from overcharge, overdischarge, and overcurrent has an external connection terminal 6 as shown in FIG. As shown in FIG. 4B, an electronic component 31 such as an integrated circuit component is mounted on the other surface on the side of the secondary battery 2 and the secondary battery 2 is mounted on both sides. A positive electrode soldering land 32 and a negative electrode soldering land 33 for connection are formed. In each figure, display of circuit patterns and through holes is omitted. An insulating paper 34 is disposed on the electronic component 31 in the positive electrode soldering land 32 and one end of the positive electrode lead plate (connecting member) 4 is disposed on the negative electrode soldering land 33, and one end of the negative electrode lead plate (connecting member) 5 is disposed on the negative electrode soldering land 33. The soldering is performed as shown in FIG.

  As shown in FIG. 5A, the circuit board 3 after the connection processing has the other end of the positive electrode lead plate 32 on the plate surface of the sealing plate 23 and the other of the negative electrode lead plate 33 with respect to the secondary battery 2. The ends are spot welded onto the other connection piece 10b of the thermal fuse 10, respectively. In this connection state, since the circuit board 3 is in a direction orthogonal to the plate surface of the sealing plate 23, as shown in FIG. 5 (b), the positive and negative lead plates 4, 5 are bent, A gap is provided between the plate surface of the circuit board 3 and the plate surface of the sealing plate 23, and is shaped so as to be substantially parallel to the sealing plate 23. Thus, the circuit board 3 is connected to the secondary battery 2, and the resin filling object 7 as shown to Fig.9 (a) is formed.

  The resin is filled in the gap between the secondary battery 2 and the circuit board 3 of the resin filling object 7, and the circuit board 3 is integrated with the secondary battery 2. At this time, it is important to resin-mold so that the height H from the bottom surface of the secondary battery 2 to the formation surface of the external connection terminal 6 of the circuit board 3 becomes a predetermined dimension, and a manufacturing method for realizing this will be described below. explain.

  As shown in FIG. 6, the lower mold 36 of the primary mold 35 is configured such that the movable part 41 can be moved to the fixed part 42 side by the biasing means 45, and the movable part 41 is provided with a vacuum suction part 43. ing. When the movable portion 41 is moved backward, the resin filling object 7 (only the secondary battery 2 and the circuit board 3 are shown in the figure) is arranged in the lower mold 36, and the movable portion 41 is moved forward, the secondary battery. The bottom surface of 2 is positioned by being pressed against the wall surface in the fixing portion 42. On the other hand, the circuit board 3 is positioned in close contact with the wall surface of the vacuum suction portion 43 by vacuum suction from the vacuum suction portion 43.

  The height dimension H from the bottom surface of the secondary battery 2 to the surface where the external connection terminals 6 of the circuit board 3 are formed varies in the height dimension h of the secondary battery 2 and the circuit board 3 is not fixed at a fixed position. Although it fluctuates due to the cause, the circuit board 3 is fixed at a fixed position by vacuum suction, and the movable portion 41 is positioned in the lower die 36 because the advance amount thereof changes according to the height dimension h of the secondary battery 2. The secondary battery 2 and the circuit board 3 thus formed have a height dimension from the bottom surface of the secondary battery 2 to the formation surface of the external connection terminal 6 of the circuit board 3 due to a change in the height dimension G of the gap between them. H is in a constant state.

  As shown in FIG. 7, the upper die 37 is lowered on the lower die 36 where the secondary battery 2 and the circuit board 3 are positioned as described above, and the secondary battery 2 is connected to the secondary battery 2 from the gate 44 provided on the upper die 37. Resin is injected into the gap between the circuit board 3. As shown in FIG. 8, the injected resin wraps around the electronic component 31 mounted on the circuit board 3 and the lead plates 4 and 5 of the positive electrode and the negative electrode and joins to the circuit board 3 to form the secondary. The undercut portion of the engagement protrusion 26 formed on the sealing plate 23 of the battery 2 is also wrapped around and joined to the sealing plate 23. A hot melt is preferable in which the resin is fluidized at a temperature that does not adversely affect the electronic component 31, the secondary battery 3, or the thermal fuse 10, and is cured when the temperature is lowered.

  Even if the temperature of the resin is relatively low, the temperature exceeds 200 ° C. Therefore, when the temperature fuse 10 whose fusing temperature is set to 104 ° C. is touched, the temperature fuse 10 is blown to stop the function of the battery pack 1 itself. I will let you. As a countermeasure, as described above, the thermal fuse 10 is covered with the heat insulating sheet 16, and the thermal fuse 16 is shielded from the heat of the resin.

  After the filled resin is cured, the upper die 37 is opened, the vacuum suction of the vacuum suction part 43 is released, and the movable part 41 is retracted, whereby the secondary battery 2 and the circuit board 3 are formed by the resin curing. The integrated primary mold body 11 can be integrated and taken out from the lower mold 36 as an intermediate finished product 8 as shown in FIG. The battery pack 1 can be formed by applying an outer covering around the intermediate finished product 8.

  The exterior covering is formed by adhering the secondary molding and the winding sheet. Before performing the secondary molding, the insulator 14 is attached to the bottom surface of the secondary battery 2.

  In the secondary molding, as shown in FIG. 9, the intermediate finished product 8 is placed in the secondary mold 46 and a resin is molded at a required portion of the intermediate finished product 8. The lower mold 47 of the secondary mold 46 is formed with a recess 50 for accommodating the intermediate finished product 8, and one side wall surface of the recess 50 is used for three external connection terminals that are urged inwardly. A protrusion 51 and a test terminal protrusion 52 are provided, and a bottom surface protrusion 54 that is urged inward is provided on the opposite side wall surface. When the intermediate finished product 8 is disposed in the recess 50 and the external connection terminal protrusion 51, the test terminal protrusion 52, and the bottom surface protrusion 54 are advanced, the external connection terminal protrusion 51 is formed on the circuit board 3. The three external connection terminals 6 are in pressure contact, and the bottom projection 54 is in pressure contact with the insulator 14 attached to the bottom surface of the secondary battery 2.

  In this state, the lower mold 47 is closed with the upper mold 48, and the resin is filled into the secondary mold 46 from the gate 53 provided on the upper mold 48. The resin is injected into the secondary mold 46 from four locations, and as shown in FIG. 10, the external connection terminals 6 and the test terminals 30 of the intermediate finished product 8 are exposed to the outside, and the primary mold body 11 and the circuit board 3 are exposed. 11 (c), the upper molded portion 17 is formed on the sealing plate 23 of the secondary battery 2, and the periphery of the insulator 14 is wrapped around the bottom surface of the secondary battery 2 to a predetermined thickness. A lower molding portion 18 fixed to the upper portion is formed, and a connection molding portion 19 is formed to connect the upper molding portion 17 and the lower molding portion 18 at the side corners of the secondary battery. As shown in FIG. 12, the connection molding portion 19 is formed of resin so that the 90 ° portion on one side of the arc side surface of the secondary battery 2 having an oval cross-sectional shape is formed at a right angle. The secondary molding body 12 shown in FIG. 2 is formed by the upper molding part 17, the lower molding part 18, and the connection molding part 19.

  A stepped portion 38 is formed near the secondary battery on the peripheral surface of the upper molded portion 17, and the winding sheet 13 is wound around the side peripheral surface of the secondary battery 2 using this as a bonding positioning line. Worn. Thereafter, the operation state is inspected using the test terminal 30, and the submerged seal 9 is stuck in the recess around the test terminal 30 for the product that has passed the inspection, and the test terminal 30 is covered and concealed by the submerged seal 9. The battery pack 1 as shown in FIG.

  In the battery pack 1 formed in this way, both shoulder portions of one flat surface are formed at arc corners where the arcs of both side surfaces of the secondary battery 2 appear on the surface, and both shoulder portions of the other surface are connected molding portions 19. Since the external connection terminal 6 is formed at an asymmetric position, reverse loading into the device can be prevented. The arc corner corresponds to the rounded shape of the corner of the device case, and can be accommodated in the device without forming a useless space.

  In the above configuration, the configuration in which the heat insulating sheet 16 is adhered to prevent the resin from being filled with the heat sensitive element such as the thermal fuse 10 from being destroyed or deteriorated is shown. A device capable of preventing a thermal influence on the heat-sensitive element can be applied until solidifying. As a form of the heat insulation treatment, a method of sticking a heat insulating sheet on the heat sensitive element and a method of covering the heat sensitive element with a heat insulating resin can be applied.

  As the heat insulating resin for covering the heat sensitive element, a resin having a higher melting temperature than the resin to be filled is selected, and PPS (polyphenylene sulfide), PA (polyamide), PAI (polyamideimide), PI (polyimide), PEEK (Polyetheretherketone) and the like are preferable, and those having excellent adhesion to the resin to be filled are more preferable.

  As the heat insulating sheet to be attached to the heat sensitive element, an acrylic resin or polyurethane sheet subjected to foaming treatment, a sheet using the above heat insulating resin, or a sheet using polyurethane, liquid crystal polymer, phenol resin or fluororesin is applied. be able to. In addition, a sheet in which a heat resistant resin is impregnated with ceramic, glass wool, glass cloth, or the like as a base layer can be used. These sheets preferably have a thickness of about 0.3 to 1.0 mm from the viewpoint of heat insulation from the resin to be filled and protection from injection pressure.

  In the above configuration, the following countermeasure structure is provided as a countermeasure structure for preventing thermal influence from the resin on the thermal fuse 10 when the resin is filled between the secondary battery 2 and the circuit board 3. Alternatively, a filling molding method can be applied.

  As shown in FIG. 13, a recess 28 is formed in the sealing plate 23 of the secondary battery 2, and the thermal fuse 10 is disposed in the recess 28. The heat insulating sheet 16 may be attached on the thermal fuse 10 so as to close the opening of the recess 28, but the same effect can be obtained by disposing other components to prevent the resin from flowing into the recess 28. Is obtained. In the case of this configuration, the temperature of the secondary battery 2 is easily transferred to the thermal fuse 10, so that the detection accuracy and response speed of detecting and operating the secondary battery 2 by the thermal fuse 10 is improved. Effect is obtained. The connection pieces 10a and 10b provided on both sides of the thermal fuse 10 are insulated from the sealing plate 23 by insulating paper 29 and 29, respectively, and the main body of the thermal fuse 10 is thermally conductive adhesive (for example, silicone resin) in the recess 28. ) Is fixed in a state where it is thermally coupled to the secondary battery 2.

  Further, by forming at least a portion of the primary mold 35 corresponding to the location of the thermal fuse 10 with a material having good thermal conductivity (for example, aluminum), the heat of the resin is dissipated to the mold side, and the temperature is increased. By suppressing the heat conduction to the fuse 10, it is possible to prevent the thermal fuse 10 from being blown at the time of filling and molding the resin.

  In addition, the primary mold die 35 is formed in its entirety or the fixing portion 42 of the lower die 36 with a material having good thermal conductivity, for example, an aluminum alloy, so that the thermal conductivity of the portion where the thermal fuse 10 is disposed can be increased. Can be increased.

  The primary molding die 35 and the secondary molding die 46 are the active parts of the resin filling object 7 or the intermediate finished product 8, for example, the positive electrode lead plate 4, the negative electrode lead plate 5, the external connection terminal 6, and the test terminal 30. An insulating layer is formed at a site corresponding to the above to prevent occurrence of short circuit or leakage due to contact of the live part with the mold. An insulating layer can be made into the metal mold | die which is excellent in heat conductivity and having insulation by giving alumite process, a fluororesin process, etc. to the metal mold | die made from aluminum.

  In the above description, the thermal fuse is described as being configured to be thermally shielded from the molded resin by the heat insulating sheet, but instead of the heat insulating sheet, the connection lead that electrically connects the secondary battery and the substrate is arranged to cover the thermal fuse. By doing so, it can be thermally shielded from the molding resin.

  The thermal fuse 10 in the configuration described above can be changed to a PTC element. As is well known, the PTC element has a very small resistance value at a normal temperature state. However, when the temperature rises to a predetermined temperature, the resistance value rapidly increases and the flowing current value is limited at once. When an excessive current due to a short circuit flows, Limits overcurrent by self-heating and rapidly increasing resistance. If the secondary battery 2 is thermally coupled to the secondary battery 2, the secondary battery 2 is heated to detect an abnormal temperature rise, and the resistance value is increased, and the current causing the abnormal temperature rise is limited to a temperature. Stop climbing.

  Even when this PTC element is used, if the resin is directly touched during resin filling and molding, the function may be destroyed. Therefore, it is necessary to provide a heat shielding structure as in the case of the thermal fuse 10.

  Furthermore, the thermal fuse 10 in the above-described configuration can be changed to a bimetal thermostat. Bimetallic thermostats form a movable contact by bonding two types of metals with different thermal expansion coefficients, and when the temperature rises to a predetermined temperature, the movable contact opens due to the deformation caused by the difference in thermal expansion coefficient and cuts off the current. When an excessive current flows due to a short circuit or the like, the current is cut off from the temperature rise due to self-heating. Further, when the secondary battery 2 is placed in thermal coupling with the secondary battery 2, it senses that the secondary battery 2 has risen in abnormal temperature, cuts off the battery current causing the abnormal temperature rise, and stops the temperature rise.

  Even when this bimetal thermostat is used, if the resin is directly touched during resin filling and molding, the function may be adversely affected by a temperature shock or the like. Therefore, it is preferable to provide a heat shielding structure as in the case of the thermal fuse 10. By covering with the heat insulating sheet, the heat insulating property is improved, and the thermal influence on the internal bimetal element is more reliably avoided.

  Using a bimetallic thermostat that is covered with a heat insulating resin except for the portion that is thermally coupled to the secondary battery can shield the heat from resin molding alone, and in this case, a heat insulating sheet is unnecessary. .

  Note that these heat-sensitive elements can be used in combination with elements having different set temperatures according to the design.

  In addition to the heat sensitive element thermally coupled to the secondary battery 2, a pattern fuse is formed on the circuit board 3 that exhibits a non-returnable current interrupt function that interrupts current when a predetermined current value is exceeded. By providing the element having the current regulation / interruption function, the reliability of the battery pack can be greatly improved. In this configuration, the pattern fuse is also affected by heat from the molded resin in a molten state like the temperature fuse 10 and the PTC element, and the characteristics of the pattern fuse are deteriorated by the same action as the subject according to the present invention. . Therefore, an element that shields the heat of the molding resin is added to the pattern fuse forming portion of the circuit board 3. Specifically, by adopting a configuration in which heat is shielded by other components excluding the resin according to claim 1 or a configuration in which a heat insulating member according to claim 2 is disposed, the thermal effect is eliminated as in the present invention. The effect which can be obtained can be acquired.

DESCRIPTION OF SYMBOLS 1 Battery pack 2 Secondary battery 3 Circuit board 7 Resin filling object 8 Intermediate finished product 10 Thermal fuse 11 Primary mold body 12 Secondary mold body 16 Thermal insulation sheet 23 Sealing plate 35 Primary mold metal mold | die

Claims (5)

A battery pack in which the secondary battery and the substrate are integrated by placing a substrate on which the external connection terminals are formed with a gap on the sealing plate side of the secondary battery and filling the gap with resin.
A battery pack comprising a heat sensitive element thermally coupled to the secondary battery in a recess formed in the sealing plate, and a heat insulating member disposed over the recess.   A battery pack in which an external connection terminal is formed with a gap on the sealing plate side of the secondary battery is disposed, and the resin filled in the gap is a battery pack in which the secondary battery and the board are integrated, A battery pack comprising: a heat-sensitive element thermally coupled to a secondary battery disposed in the gap; and a heat-insulating coating layer formed on the heat-sensitive element.   The battery pack according to claim 1, wherein the heat sensitive element is a thermal fuse.   The battery pack according to claim 1, wherein the heat sensitive element is a PTC element.   The battery pack according to any one of claims 1 to 4, wherein the heat-sensitive element is a bimetal thermostat.

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