Printed circuit board, its manufacturing method and battery pack including the same

Abstract

According to one aspect of the present invention, a printed circuit board includes an inner layer, a first insulating layer formed on the inner layer, a first copper foil layer formed on the first insulating layer, and a solder resist layer formed on the first copper foil layer, and when a metal tab is welded onto the solder resist layer, a weld is formed that connects the metal tab and the first copper foil layer, and a gap is formed in a portion adjacent to the weld.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0134806 dated October 12, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a printed circuit board and a battery pack including the same, and more particularly to a printed circuit board having excellent durability and a battery pack including the same. [Background technology]

[0003] In modern society, as the use of portable devices such as mobile phones, laptops, video cameras, and digital cameras has become commonplace, technological development in fields related to these mobile devices is accelerating. Furthermore, rechargeable secondary batteries are used as the power source for electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (P-HEVs), and other vehicles as a way to address air pollution caused by existing gasoline-powered vehicles that use fossil fuels, and so there is a growing need for the development of secondary batteries.

[0004] Currently commercially available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Of these, lithium secondary batteries are attracting attention due to their advantages over nickel-based secondary batteries, such as almost no memory effect, freedom in charging and discharging, a very low self-discharge rate, and high energy density.

[0005] Such lithium secondary batteries mainly use lithium-based oxides and carbon materials as positive and negative electrode active materials, respectively, and include an electrode assembly in which positive and negative electrode plates coated with the positive and negative electrode active materials are arranged with a separator sandwiched between them, and a battery case that hermetically houses the electrode assembly together with an electrolyte.

[0006] Generally, lithium secondary batteries are classified into can-type secondary batteries, in which the electrode assembly is housed in a metal can, and pouch-type secondary batteries, in which the electrode assembly is housed in a pouch made of an aluminum laminate sheet, depending on the shape of the exterior material.

[0007] While secondary batteries used in small devices typically have two or three battery cells, secondary batteries used in medium- to large-sized devices such as automobiles typically use battery modules in which multiple battery cells are electrically connected. These battery modules improve capacity and output by connecting multiple battery cells in series or parallel to form a battery cell stack. One or more battery modules may also be installed with various control and protection systems, such as a battery management system (BMS) and a cooling system, to form a battery pack.

[0008] In this regard, a printed circuit board (PCB) used as a component of a battery management system (BMS) of a battery pack generally includes an inner layer, and insulating layers and copper foil layers laminated above and below the inner layer. When welding is performed to connect a metal tab to the printed circuit board, there is a risk that the inner layer of the printed circuit board may be damaged by the welding.

[0009] In particular, when the inner layer of the printed circuit board is damaged, not only is the inner layer pattern damaged, making it difficult for the printed circuit board to function, but the insulating layer is also destroyed, increasing the possibility of wire breakage.

[0010] Therefore, there is a need for a structure that can prevent damage to the inner layers of a printed circuit board when welding a metal tab onto the printed circuit board. Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is to provide a printed circuit board capable of preventing damage to an inner layer that occurs during welding, and a battery pack including the same.

[0012] However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and unmentioned problems will be clearly understood by those having ordinary skill in the art to which the present invention pertains from this specification and the accompanying drawings. [Means for solving the problem]

[0013] A printed circuit board according to one aspect of the present invention includes an inner layer, a first insulating layer formed on the inner layer, a first copper foil layer formed on the first insulating layer, and a solder resist layer formed on the first copper foil layer. When a metal tab is welded onto the solder resist layer, a weld is formed that connects the metal tab and the first copper foil layer, and a gap is formed in a portion adjacent to the weld.

[0014] The gap may separate the metal tab and the first copper foil layer.

[0015] When the metal tab is welded, the solder resist layer is partially or entirely removed to form the gap.

[0016] The gap may be between 50 μm and 200 μm.

[0017] The solder resist layer can cover the entire surface of the first copper foil layer.

[0018] The solder resist layer can cover a portion of the first copper foil layer.

[0019] The solder resist layer may cover an outer edge of the first copper foil layer.

[0020] The outer size of the solder resist layer is formed to be larger than the outer size of the first copper foil layer.

[0021] The size of the solder resist layer is smaller than or equal to the size of the metal tab.

[0022] The first copper foil layer is formed to be smaller than the metal tab.

[0023] The metal tab is connected to the first copper foil layer by the welding.

[0024] A method for manufacturing a printed circuit board according to another aspect of the present invention includes forming an inner layer, a first insulating layer formed on the inner layer, a first copper foil layer formed on the first insulating layer, and forming a solder resist layer on the first copper foil layer, wherein when a metal tab is welded onto the solder resist layer, a weld is formed that connects the metal tab and the first copper foil layer, and a gap is formed in a portion adjacent to the weld.

[0025] A battery pack according to yet another aspect of the present invention may include the printed circuit board. [Effects of the Invention]

[0026] The printed circuit board of the present invention includes a solder resist layer on the copper foil layer, thereby preventing damage to the inner layers of the printed circuit board when the metal tab is welded.

[0027] The effects of the present invention are not limited to the effects described above, and effects not mentioned will be clearly understood by those having ordinary skill in the art to which the present invention pertains from this specification and the accompanying drawings. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a cross-sectional view showing a structure of a printed circuit board according to an embodiment of the present invention; [Figure 2] FIG. 2 is a plan view of the printed circuit board of FIG. 1 as viewed from above. [Figure 3] 2 is a cross-sectional view showing the structure of the printed circuit board of FIG. 1 before a metal tab is welded to the board. [Figure 4] 10 is a cross-sectional view showing a structure of a printed circuit board according to another embodiment of the present invention. [Figure 5] 5 is a cross-sectional view showing the structure of a printed circuit board obtained by partially modifying the printed circuit board of FIG. 4. [Figure 6] FIG. 6 is a plan view of the printed circuit board of FIG. 5 as viewed from above. [Figure 7] 6 is a cross-sectional view showing the structure before a metal tab is welded to the printed circuit board of FIG. 5. FIG. [Figure 8] 1 is a cross-sectional view showing the structure of a printed circuit board in the process of welding a metal tab; DETAILED DESCRIPTION OF THE INVENTION

[0029] While the present invention may be embodied in many different forms, it is to be understood that the invention is not limited to the embodiments set forth herein.

[0030] In order to clearly explain the present invention, parts that are not necessary for the explanation will be omitted, and the same reference numerals will be used throughout the specification to refer to the same or similar components.

[0031] In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for the convenience of explanation, and the present invention is not necessarily limited to the drawings. In the drawings, thicknesses are exaggerated to clearly show various layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for the convenience of explanation.

[0032] Furthermore, when a layer, film, region, plate, or other part is said to be "above" another part, this does not only mean that it is "directly above" that part, but also includes cases where there is another part in between. Conversely, when a part is said to be "directly above" another part, it means that there is no other part in between. Note that being "above" a reference part means being located above or below the reference part, and does not necessarily mean being "above" in the opposite direction of gravity.

[0033] Furthermore, throughout the specification, when a part is described as "comprising" a certain element, this does not mean that it can further include other elements, unless otherwise specified.

[0034] Furthermore, throughout the specification, "in a plane" means a view of the subject matter as viewed from above, and "in cross section" means a view of the subject matter as viewed from the side across a vertical cross section.

[0035] The terms "first" and "second" used in this application may be used to describe various components, but the components should not be limited by the terms. The terms are used only to distinguish one component from another.

[0036] Hereinafter, a printed circuit board according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3 and 8. FIG.

[0037] Fig. 1 is a cross-sectional view showing the structure of a printed circuit board according to an embodiment of the present invention. Fig. 2 is a top plan view of the printed circuit board of Fig. 1. Fig. 3 is a cross-sectional view showing the structure of the printed circuit board of Fig. 1 before a metal tab is welded to the board. Fig. 8 is a cross-sectional view showing the structure of the printed circuit board in the process of welding a metal tab.

[0038] 1, a printed circuit board (PCB) 100 according to this embodiment includes an inner layer 200, a first insulating layer 310 formed on the inner layer 200, and a second insulating layer 320 formed on the inner layer 200. The printed circuit board 100 also includes a first copper foil layer 410 formed on the first insulating layer 310, a second copper foil layer 420 formed on the second insulating layer 320, and a solder resist layer 500 formed on the first copper foil layer 410.

[0039] In this case, the inner layer 200 may be a paper core layer impregnated with epoxy resin or a glass fiber layer impregnated with epoxy resin, or more specifically, FR-4. The first insulating layer 310 and the second insulating layer 320 may be formed of the same material, which may be prepreg (PPG). The solder resist layer 500 according to this embodiment may be a photo solder resist (PSR) layer.

[0040] Conventional printed circuit boards have a risk of damaging the inner layer when welding to a metal tab. If the inner layer is damaged, not only can the inner layer pattern be damaged, but the insulating layer can also be destroyed, increasing the possibility of wire breakage.

[0041] 8, in the printed circuit board 100 according to this embodiment, when the metal tab 600 is welded onto the solder resist layer 500, a weld 700 is formed that joins the metal tab 600 and the first copper foil layer 410, and a gap G is formed in the portion adjacent to the weld 700. In this case, the metal tab 600 may be a copper tab or a nickel tab, and more specifically, may be a nickel tab, but is not limited thereto.

[0042] 8, although the solder resist layer 500 is not shown in FIG. 8, the gap G formed between the metal tab 600 and the first copper foil layer 410 can be equal to or correspond to the thickness of the solder resist layer 500.

[0043] The gap G may separate the metal tab 600 and the first copper foil layer 410, and in particular, the gap G may be formed on both sides of the weld 700 to ensure the separation distance between the metal tab 600 and the first copper foil layer 410.

[0044] When the metal tab 600 is welded to the printed circuit board 100, the solder resist layer 500 is partially or entirely removed to form the gap G. This is because the solder resist layer 500 is removed by heat generated by welding. Even if the solder resist layer 500 is partially or entirely removed, the metal tab 600 can be welded to the printed circuit board 100 because a portion of the metal tab 600 is connected to the first copper foil layer 410 by the welding. At this time, the gap G increases the distance between the metal tab 600 and the inner layer 200, thereby preventing a portion of the molten metal tab 600 from reaching the inner layer 200 even when the metal tab 600 is welded, thereby preventing damage to the inner layer 200. Therefore, when the metal tab 600 is welded, the solder resist layer 500 is partially or entirely removed, forming the gap G between the metal tab 600 and the first copper foil layer 410. At this time, even if a gap G is formed, the metal tab 600 can be connected to the first copper foil layer 410 by the welding, and in particular, the metal tab 600 and the first copper foil layer 410 may be connected via a welding portion 700.

[0045] The thickness of the solder resist layer 500 according to this embodiment may be 50 μm to 200 μm, preferably 75 μm to 150 μm, and more preferably 80 μm to 100 μm.

[0046] Therefore, the gap G may also be set to 50 μm to 200 μm, preferably 75 μm to 150 μm, and more preferably 80 μm to 100 μm.

[0047] Meanwhile, the solder resist layer 500 may cover the entire surface of the first copper foil layer 410. Referring to FIG. 2, the entire surface of the first copper foil layer 410 refers to the entire surface of the first copper foil layer 410 when viewed from above. Therefore, as shown in FIG. 2, the solder resist layer 500 may cover the entire surface of the first copper foil layer 410. In this case, the size of the solder resist layer 500 may be the same as or larger than the size of the first copper foil layer 410. Therefore, when the size of the solder resist layer 500 is larger than the size of the first copper foil layer 410, an outer surface 510 of the solder resist layer is formed. The outer surface 510 of the solder resist layer allows the metal tab 600 to be stably formed on the printed circuit board 100 and the solder resist layer 500 and welded thereto.

[0048] 3, the size of the solder resist layer 500 may be smaller than or the same as the size of the metal tab 600. The size of the first copper foil layer 410 is smaller than the size of the metal tab 600. By forming the first copper foil layer 410 to have such a size, it is possible to ensure welding stability between the metal tab 600 and the printed circuit board 100.

[0049] Hereinafter, a printed circuit board according to another embodiment of the present invention will be described with reference to Figures 4 to 8. Since some of the content overlaps with the content described above, only the parts that are different from the content described above will be described.

[0050] Fig. 4 is a cross-sectional view showing the structure of a printed circuit board according to another embodiment of the present invention. Fig. 5 is a cross-sectional view showing the structure of a printed circuit board obtained by partially modifying the printed circuit board of Fig. 4. Fig. 6 is a plan view of the printed circuit board of Fig. 5 as viewed from above. Fig. 7 is a cross-sectional view showing the structure of the printed circuit board of Fig. 5 before a metal tab is welded thereto.

[0051] 4 to 6, the solder resist layer 500 of the printed circuit board according to this embodiment may cover a portion of the first copper foil layer 410. In particular, the solder resist layer 500 may cover the outer edge of the first copper foil layer 410. Furthermore, an inner edge 520 of the solder resist layer is formed as a portion on the solder resist layer 500 where the solder resist layer 500 and the outer edge of the first copper foil layer 410 overlap.

[0052] More specifically, referring to Fig. 4, the solder resist layer 500 may be formed so that there is no overlapping portion with the first copper foil layer 410. Also, referring to Fig. 5, an overlapping portion between the solder resist layer 500 and the first copper foil layer 410 is formed so that an inner edge portion 520 of the solder resist layer is formed. Therefore, the solder resist layer 500 is stably formed on the first copper foil layer 410 by the inner edge portion 520 of the solder resist layer. Also, as shown in Fig. 7, a metal tab 600 is formed on the upper portion of the solder resist layer 500.

[0053] As described above, since the solder resist layer 500 covers the outer edge of the first copper foil layer 410, the outer size of the solder resist layer 500 may be larger than the outer size of the first copper foil layer 410, or the outer size of the solder resist layer 500 may be the same as the outer size of the first copper foil layer 410. In this case, the outer size may refer to the outer sizes of the solder resist layer 500 and the first copper foil layer 410 shown in FIG. 6. In addition, the inner size of the solder resist layer 500 may be smaller than the outer size of the first copper foil layer 410.

[0054] By forming the metal tab 600 to the above size, as shown in FIG. 8, the metal tab 600 is stably formed on the solder resist layer 500, and when welding is performed, a gap G is formed to prevent damage to the inner layer.

[0055] Hereinafter, a method for manufacturing a printed circuit board according to another embodiment of the present invention will be described. All of the above-described details regarding the printed circuit board are applicable to the method for manufacturing a printed circuit board according to this embodiment. Since there is overlap with the above-described details, only differences from the above-described details will be described.

[0056] The method for manufacturing a printed circuit board according to this embodiment includes step S100 of forming an inner layer 200, a first insulating layer 310 formed on the inner layer 200, and a first copper foil layer 410 formed on the first insulating layer 310, and step S200 of forming a solder resist layer 500 on the first copper foil layer 410. When a metal tab 600 is welded onto the solder resist layer 500, a weld 700 is formed that connects the metal tab 600 and the first copper foil layer 410, and a gap G is formed adjacent to the weld 700. The gap G is also formed on both sides of the weld 700.

[0057] In addition, the method for manufacturing a printed circuit board according to this embodiment may further include forming a second insulating layer 320 formed below the inner layer 200 and a second copper foil layer 420 formed below the second insulating layer 320 in step S100 of forming the inner layer 200, the first insulating layer 310 formed on the upper part of the inner layer 200, and the first copper foil layer 410 formed on the upper part of the first insulating layer 310.

[0058] 8, although the solder resist layer 500 is not shown in FIG. 8, the gap G formed between the metal tab 600 and the first copper foil layer 410 can be equal to or correspond to the thickness of the solder resist layer 500.

[0059] The gap G may separate the metal tab 600 and the first copper foil layer 410, and in particular, the gap G may be formed on both sides of the weld 700 to ensure the separation distance between the metal tab 600 and the first copper foil layer 410.

[0060] In this case, the thickness of the solder resist layer 500 may be 50 μm to 200 μm, preferably 75 μm to 150 μm, and more preferably 80 μm to 100 μm.

[0061] Therefore, the gap G may also be set to 50 μm to 200 μm, preferably 75 μm to 150 μm, and more preferably 80 μm to 100 μm.

[0062] When the metal tab 600 is welded to the printed circuit board 100, the solder resist layer 500 is partially or entirely removed so that the gap G is formed. This is because the solder resist layer 500 is removed by the heat generated by welding. Even if the solder resist layer 500 is partially or entirely removed, the metal tab 600 can be welded to the printed circuit board 100 because a portion of the metal tab 600 is connected to the first copper foil layer 410 by the welding. At this time, the gap G increases the distance between the metal tab 600 and the inner layer 200, so that even when the metal tab 600 is welded, a portion of the molten metal tab 600 does not reach the inner layer 200, thereby preventing damage to the inner layer 200.

[0063] Therefore, when the metal tab 600 is welded, a part or the whole of the solder resist layer 500 is removed, forming a gap G between the metal tab 600 and the first copper foil layer 410. Even if the gap G is formed, the metal tab 600 can be connected to the first copper foil layer 410 by the welding, and in particular, the metal tab 600 and the first copper foil layer 410 may be connected via the weld 700.

[0064] Meanwhile, the solder resist layer 500 may cover the entire surface of the first copper foil layer 410. Alternatively, the solder resist layer 500 may cover a portion of the first copper foil layer 410. In particular, the solder resist layer 500 may cover the outer edge of the first copper foil layer 410. Furthermore, an inner edge 520 of the solder resist layer is formed as a portion on the solder resist layer 500 at a position where the solder resist layer 500 and the outer edge of the first copper foil layer 410 overlap.

[0065] By manufacturing the printed circuit board in the above manner, damage to the inner layer of the printed circuit board can be prevented when welding the metal tab.

[0066] A battery pack according to yet another embodiment of the present invention will now be described.

[0067] The battery pack according to this embodiment includes the printed circuit board described above. In addition, the battery pack according to this embodiment may be configured by packing one or more battery modules according to this embodiment together with a battery management system (BMS) that manages the temperature and voltage of the battery and a cooling device. Therefore, the printed circuit board can be used as a component of the battery management system (BMS).

[0068] The battery pack can be applied to various devices, including transportation means such as electric bicycles, electric cars, and hybrid cars, but the present invention is not limited thereto and can be applied to various devices that can use a battery module, which also falls within the scope of the present invention.

[0069] Although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and various modifications may be made by a person having ordinary skill in the art to which the invention pertains without departing from the gist of the present invention as claimed in the claims, and such modifications should not be understood separately from the technical ideas and perspectives of the present invention. [Explanation of symbols]

[0070] 100: Printed circuit board 200: Inner layer 310: First insulating layer 410: First copper foil layer 500: Solder resist layer 600: Metal tab 700: Welded parts

Claims

1. The inner layer and a first insulating layer formed on the inner layer; a first copper foil layer formed on the first insulating layer; a solder resist layer formed on the first copper foil layer; A printed circuit board comprising: When a metal tab is welded onto the solder resist layer, a welded portion is formed that connects the metal tab and the first copper foil layer, and a gap is formed as an air gap in a portion adjacent to the welded portion, When the metal tab is welded, the solder resist layer is partially or entirely removed to form the gap.

2. The printed circuit board of claim 1 , wherein the gap separates the metal tab and the first copper foil layer.

3. 3. The printed circuit board according to claim 1, wherein the gap is between 50 μm and 200 μm.

4. The printed circuit board of claim 1 , wherein the solder resist layer covers the entire surface of the first copper foil layer.

5. The printed circuit board of claim 1 , wherein the solder resist layer covers a portion of the first copper foil layer.

6. The printed circuit board of claim 5 , wherein the solder resist layer covers an outer edge of the first copper foil layer.

7. The printed circuit board of claim 6 , wherein the outer size of the solder resist layer is larger than the outer size of the first copper foil layer.

8. The printed circuit board of claim 1 , wherein the solder resist layer is formed to be smaller than or equal to the size of the metal tab.

9. The printed circuit board of claim 1 , wherein the first copper foil layer is smaller than the metal tab.

10. The printed circuit board of claim 1 , wherein the metal tab is connected to the first copper foil layer by the welding.

11. 2. The method for manufacturing a printed circuit board according to claim 1, forming an inner layer, a first insulating layer formed on the inner layer, and a first copper foil layer formed on the first insulating layer; forming a solder resist layer on the first copper foil layer; Including, When a metal tab is welded onto the solder resist layer, a welded portion is formed that connects the metal tab and the first copper foil layer, and a gap is formed as an air gap in a portion adjacent to the welded portion; When the metal tab is welded, the solder resist layer is partially or entirely removed to form the gap.

12. The method of claim 11 , wherein the gap separates the metal tab and the first copper foil layer.

13. The method for manufacturing a printed circuit board according to claim 11 or 12, wherein the gap is 50 μm to 200 μm.

14. The method of claim 11 , wherein the solder resist layer covers the entire surface of the first copper foil layer.

15. The method of claim 11 , wherein the solder resist layer covers a portion of the first copper foil layer.

16. The method of claim 15 , wherein the solder resist layer covers an outer edge of the first copper foil layer.

17. A battery pack comprising the printed circuit board of claim 1.

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