Circuit board assembly for battery device

Abstract

Printed circuit board assembly for a battery device, comprising: a circuit board body (110) having a plurality of conductive lines (111) arranged in parallel, the conductive line (111) comprising a first metal and a second metal covering an outer surface of the first metal, and the second metal having a lower hardness than the first metal; a branch structure (120) comprising a branch connection portion (121) formed by the first metal and a sensing portion (122) connected to the branch connection portion (121), the sensing portion (122) being configured to collect battery information; the branch connection portion (121) comprising at least two rows of through-holes (a) along an arrangement direction of the plurality of conductive lines (111), positions of the through-holes (a) corresponding to positions of the conductive lines (111), at least one of the through-holes (a) having a solder joint therein, and the solder joint being welded to the conductive line (111); a fixing plate (130) covering a surface of the solder joint and fixedly connected to the branch connection portion (121), wherein a dimension of the fixing plate (130) along the arrangement direction of the plurality of conductive lines (111) is represented by W1, a dimension of the through-hole (a) along the arrangement direction of the plurality of conductive lines (111) is represented by R, wherein 0.01≤R / W1≤2 is satisfied.

Description

Technical area

[0001] The present application relates to the technical field of printed circuit boards and, in particular, to a printed circuit board assembly for a battery device. BACKGROUND

[0002] Currently, low-voltage sensing harnesses used in battery devices mainly include two types: FPC (Flexible Printed Circuit) and FFC (Flat Flexible Cable).

[0003] FPC is formed by etching a copper wire as a core and encapsulating it with an insulating material as a protective film. It has the advantages of thin thickness and small volume, but its production cost is relatively high, and a lot of core material must be cut off during the formation process when branches are formed.

[0004] FFCs are formed using tinned copper as the core and encapsulated with a protective film. It has the advantage of being soft and flexible, but they typically use punched fuses, which can generate sparks when triggered, increasing the risk of short circuits in the battery pack. Although the use of etched fuses avoids the problem of sparks, the cost is relatively high. SUMMARY

[0005] The aim of the present application is to solve at least part of the above-mentioned technical problems, which is achieved by the following technical solution: In a first aspect, the present application proposes a printed circuit board assembly for a battery device, including a printed circuit board body, a branch structure, and a mounting plate. The printed circuit board body includes a plurality of conductive lines arranged in parallel, the conductive line comprising a first metal and a second metal covering an outer surface of the first metal, the second metal having a lower hardness than the first metal; the branch structure includes a branch connection portion formed by the first metal and a sensing portion connected to the branch connection portion, the sensing portion being configured to be connected to a battery and to collect battery information.wherein the branch connection portion has at least two rows of through-holes along an arrangement direction of the plurality of conductive lines, wherein positions of the through-holes correspond to positions of the conductive lines, wherein at least one through-hole has a solder joint therein, and the solder joint is welded to the conductive line; wherein the fixing plate is connected to the branch connection portion, a dimension of the fixing plate along the arrangement direction of the plurality of conductive lines is represented by W1, a dimension of the through-hole along the arrangement direction of the plurality of conductive lines is represented by R, wherein 0.01≤R / W1≤2 is satisfied.

[0006] The technical solution proposed by the present application has at least the following technical effects: In the present application, the branch connection portion is welded to the conductive line of the circuit board body through the solder joint in the through-hole and is reinforced by the fixing plate to prevent bending and distortion of the branch connection portion when heated during welding; in addition, the ratio of the diameter of the through-hole to the width of the fixing plate is appropriately designed, which can not only provide a sufficient fixing effect for the branch connection portion to eliminate bending or even buckling, but also ensure reliable welding and avoid high local resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] To better combine the content shown in the drawings with the content described in the detailed description, a brief introduction to the drawings is provided below. It should be understood that the drawings mentioned below only illustrate some embodiments of the related technical solutions and the technical solutions of the present application. Those skilled in the art can also create drawings showing other embodiments without creative effort.

[0008] In particular, the description of the drawings is as follows: Fig. 1 is a schematic structural diagram of a circuit board assembly for a battery device according to some embodiments of the present application; Fig. Figure 2 is an enlarged schematic structural diagram of section A in Fig. 1; Fig. 3 is a schematic structural diagram of a branch structure according to some embodiments of the present application; Fig. 4 is a schematic diagram showing the connection between a branch structure and a mounting plate according to some embodiments of the present application; Fig. 5 is a schematic structural diagram of the printed circuit board body according to some embodiments of the present application.

[0009] In particular, the designations of the reference numbers in the drawings are as follows: 100 - PCB assembly for battery device; 110 - PCB body; 111 - conductive line; 120 - branch structure; 121 - branch connection portion; 122 - sensing portion; 123 - buffer arm; 130 - fixing plate; 140 - connector seat; 150 - battery aluminum busbar; a - through hole; g - securing structure; B1 - first main layer; B2 - second main layer; E1 - first branch structure; E2 - second branch structure; K1 - first fixing plate; K2 - second fixing plate; X - first direction; Y - second direction; Z - third direction. DETAILED DESCRIPTION

[0010] To clarify the contents of the embodiments of the present application, the following description is presented in conjunction with the drawings. It should be understood that the content mentioned below is only a part of the embodiments of the present application, rather than an exhaustive list of all embodiments. Therefore, other embodiments obtained based on the following embodiments without creative effort fall within the scope of the present application.

[0011] It should be understood that the terms used herein are for the sole purpose of describing particular embodiments and are not intended to limit technical solutions, unless explicitly indicated otherwise by context. For example, the use of "a," "an," and "the" to modify features does not preclude the possibility that such features may be present in a plurality in other embodiments.

[0012] It should be understood that the terms "include," "comprising," and "having" are open-ended and indicate the presence of stated features, but do not preclude the possibility that the embodiment may include other features. Likewise, the use of terms such as first, second, etc., to describe a plurality of features is merely to distinguish one feature from another, and unless otherwise indicated by the context, such terms do not imply order or sequence.

[0013] It should be understood that, unless otherwise indicated by the context, terms such as "arranged," "connected," and "installed" should be interpreted broadly. They may refer, for example, to a fixed connection, a detachable connection, or an integral connection; they may be directly connected or indirectly connected via intermediate media. Those skilled in the art will be able to understand the specific meanings of these terms in context.

[0014] Additionally, for ease of description, spatial relationship terms are used to describe the position of one feature relative to another, such as "inner," "outer," "end," "side," "upper," "middle," "lower," "high," "low," "axial," "circumferential," "radial," "horizontal," "vertical," "first direction," "second direction," etc. It can be understood that the spatial relationships between two features include specific situations other than those shown in the drawings.

[0015] The embodiments of the present application will now be described in conjunction with the drawings.

[0016] With reference to Fig. 1-5, the present application provides a printed circuit board assembly 100 for a battery device, including a printed circuit board body 110, a branch structure 120, and a mounting plate 130. The printed circuit board body 110 includes a plurality of conductive lines 111 arranged in parallel, wherein the conductive line 111 comprises a first metal and a second metal covering an outer surface of the first metal, and wherein the second metal has a lower hardness than the first metal. The branch structure 120 includes a branch connection portion 121 formed by the first metal and a sensing portion 122 connected to the branch connection portion 121, and wherein the sensing portion 122 is configured to be connected to a battery and to collect battery information.The branch connection portion 121 has at least two rows of through-holes a along an arrangement direction of the plurality of conductive lines 111, wherein positions of the through-holes a correspond to positions of the conductive lines 111, wherein at least one through-hole a has a soldering (or welding) point therein, and the soldering point is welded to the conductive line 111. The fixing plate 130 is connected to the branch connection portion 121, wherein a dimension of the fixing plate 130 along the arrangement direction of the plurality of conductive lines 111 is represented by W1, a dimension of the through-hole a along the arrangement direction of the plurality of conductive lines 111 is represented by R, and 0.01≤R / W1≤2 is satisfied.

[0017] In the present application, the branch connection portion 121 is welded to the conductive line 111 of the circuit board body 110 through the solder joint in the through-hole a, and the fixing plate 130 is arranged for reinforcement to prevent bending and distortion of the branch connection portion 121 when heated during welding. In addition, the ratio of a diameter of the through-hole to the width of the fixing plate 130 is appropriately designed so that the fixing plate 130 can not only provide a sufficient fixing effect for the branch connection portion 121 to eliminate bending or even buckling, but also ensure reliable welding between the solder joint in the through-hole a and the conductive line 111 to avoid high local resistance.

[0018] Furthermore, if the ratio R / W1 is too large, it indicates that the solder joint is large while the fixing plate 130 is narrow, resulting in insufficient fixing effect on the branch connection portion 121, which may further cause bending or even buckling of the branch connection portion 121; if the ratio R / W1 is too small, it indicates that the solder joint is small while the fixing plate 130 is too wide. Although the fixing effect is sufficient, the small solder joint may lead to unreliable welding and high local resistance, and the excessively wide fixing plate 130 will also occupy too much internal space of the battery pack. Therefore, the ratio R / W1 should be appropriate; for example, the ratio R / W1 may be 0.01, 1, or 2.

[0019] It should be noted that the mounting plate 130 can be an integral piece or a plurality of separate small pieces. In some embodiments, the length of the integral mounting plate 130 or the sum of the lengths of a plurality of small pieces is approximately equal to the length of the straight section of the circuit board body 110. Additionally, in some embodiments, R represents the diameter of the through-hole a, W1 represents the width of the mounting plate 130, and the mounting plate 130 is a thermal printing film.

[0020] Specifically, in some embodiments, the direction along which the conductive lines 111 are arranged in parallel (i.e., the arrangement direction) is the first direction X, the extension direction of the conductive lines is the second direction Y, and the thickness direction of the mounting plate 130 is the third direction Z, and thus the first direction X, the second direction Y, and the third direction Z are perpendicular to each other.

[0021] In some embodiments, a distance between the conductive line 111 having the solder joint therein and the conductive line 111 adjacent thereto is represented by H1, satisfying 0.3 mm≤H1≤2 mm.

[0022] In the above embodiments, if the pitch between the conductive lines 111 is too small, short circuits are likely to occur; if the pitch between the conductive lines 111 is too large, the number of conductive lines 111 that can be arranged in the circuit board body 110 would be too few to accommodate the collection of a plurality of rows of batteries. In addition, the pitch of the conductive lines 111 also determines the pitch of the through-holes; if the through-holes are too close, the strength of the branch connection portion 121 would be insufficient. Therefore, the pitch H1 of the conductive lines 111 should be appropriate; for example, the pitch H1 may be 0.3 mm, 1 mm, or 2 mm.

[0023] In some embodiments, with reference to Fig. 3, each branch connection portion 121 is provided with a plurality of rows of through holes a along the extending direction of the conductive line 111.

[0024] In some embodiments, a dimension of the branch connection portion 121 along the extending direction of the conductive line 111 is represented by L1, a number of through-holes a is represented by n, an area of ​​the through-holes a is represented by S, where 0.3≤L1 / (n*S)≤0.6 is satisfied.

[0025] In the above embodiments, if the value of L1 / (n*S) is too small, it means that the proportion of through holes a of the branch connection portion 121 is too large, which makes the branch connection portion 121 easily broken or damaged during transportation, formation, and welding of the branch connection portion 121; if the value of L1 / (n*S) is too large, it indicates that the through holes a in the branch connection portion 121 are fewer and / or smaller, corresponding to fewer and / or smaller solder joints, which is detrimental to welding reliability and may lead to high local resistance. Therefore, the value of L1 / (n*S) should be appropriate, for example, it may be 0.3, 0.5, or 0.6.

[0026] It should be noted that each branch connection portion 121 has at least two rows of through-holes a, the plurality of through-holes a being spaced in respective rows along the second direction Y and the plurality of through-holes a being spaced in respective rows along the first direction X.

[0027] In some embodiments, along the extending direction of the conductive line 111, a distance between adjacent rows of through-holes a is represented by P, satisfying 0.5 mm≤P≤1.5 mm.

[0028] In some embodiments, a thickness of the mounting plate 130 is represented by d, where d≥0.03 mm and P≤1.2 mm are satisfied.

[0029] In the above embodiments, if the through holes a are too close, the strength of the branch connecting portion 121 would be insufficient, and warping may easily occur, thereby requiring a greater thickness of the fixing plate 130.

[0030] It should be noted that the shape of the through holes a is not necessarily circular, the through hole may also have rectangular or other shapes, which is not limited herein.

[0031] In some embodiments, a dimension of the mounting plate 130 along the extending direction of the conductive line 111 is represented by L2, where 0.01≤L1 / L2≤1 is satisfied.

[0032] In the above embodiments, if the ratio L1 / L2 is too small, it indicates that the width of the branch connection portion 121 is too small, resulting in a smaller number or size of solder joints, which is detrimental to improving welding reliability and current-carrying capacity; if the ratio L1 / L2 is too large, it indicates that the branch connection portion 121 has a larger width while the fixing plate 130 is small, which makes positioning during installation and fixing of the fixing plate 130 troublesome, and if the positioning is not accurate, it may not properly compress the branch structure 120. Therefore, the ratio of L1 / L2 should be appropriate, for example, it may be 0.01, 0.5, or 1.

[0033] In some embodiments, a width of the conductive line 111 is represented by W2 and satisfies 0.5 mm≤R / W2≤2 mm.

[0034] In the above embodiments, if the ratio R / W2 is too large, it indicates that the solder joint has a width that is too large compared to the width of the conductive line 111, which may cause collection errors by bridging one conductive line 111 to an adjacent conductive line 111 if the pitch of the conductive lines is small; if the ratio R / W2 is too small, it indicates that the solder joint has a width that is too small compared to the width of the conductive line 111, which may result in insufficient current flow. Therefore, the ratio of R / W2 should be appropriate; for example, it may be 0.5 mm, 1 mm, or 2 mm.

[0035] It should be noted that the first metal in the conductive line 111 has a flat shape, with its width direction being the first direction X. The second metal serves to facilitate welding and may completely or incompletely cover the first metal along the periphery of the first metal. In addition, the second metal may continuously or intermittently cover the first metal along the second direction Y. The conductive line 111 as a whole may also have a flat shape, with its width direction running along the first direction X.

[0036] In some embodiments, a thickness of the mounting plate 130 is represented by d, where 0.03 mm≤d≤0.1 mm and 0.0006≤d / W1≤0.05 are satisfied.

[0037] In some embodiments, if the thickness of the fixing plate 130 is too thin, the fixing effect would be insufficient and it would easily buckle, whereas if the fixing plate 130 is too thick, it would occupy more space in the third direction Z and be heavier. Therefore, the value of the thickness of the fixing plate 130 d should be appropriate; for example, it may be 0.03 mm, 0.05 mm, or 0.1 mm.

[0038] In addition, if the ratio d / W1 is too large, it indicates that the mounting plate 130 is too thick while being too narrow in width, which is detrimental to space saving, weight reduction, and positioning of the mounting plate 130; if the ratio d / W1 is too small, it indicates that the mounting plate 130 is thin while being large in width, making the mounting plate 130 itself more likely to buckle or break due to insufficient strength. Therefore, the ratio d / W1 should be appropriate, for example, it can be 0.0006, 0.01, or 0.05.

[0039] In some embodiments, a dimension of the branch connection portion 121 along the arrangement direction of the plurality of conductive lines 111 is represented by W2, where W2≤W1 and 0.03 mm≤d≤0.06 mm are satisfied.

[0040] In the above embodiments, the dimension of the fixing plate 130 in the first direction X is larger than that of the branch connecting portion 121, and the fixing plate 130 completely covers and extends beyond the branch connecting portion 121, thereby ensuring that the branch connecting portion 121 does not warp, so that the thickness of the fixing plate 130 can be set slightly thinner. For example, d can be 0.03 mm, 0.05 mm, or 0.06 mm.

[0041] In some embodiments, the fixing plate 130 is arranged at both ends of the branch connecting portion 121 in the thickness direction of the branch connecting portion 121, satisfying 0.03 mm≤d≤0.05 mm.

[0042] In the above embodiments, both sides of the branch connection portion 121 are fixed in the third direction Z by the fixing plate 130, resulting in greater overall structural strength, so the thickness of the fixing plate 130 can be set even thinner. For example, d can be 0.03 mm, 0.04 mm, or 0.05 mm.

[0043] In some embodiments, the mounting plate 130 is adhesively attached to the branch connection portion 121 and the circuit board body 110.

[0044] In some embodiments, the plurality of conductive lines 111 are each connected to the plurality of branch connection portions 121 in a one-to-one correspondence, and each branch connection portion 121 is welded to the corresponding conductive line 111 via a solder joint formed in the through-hole a corresponding to the corresponding conductive line 111 thereon.

[0045] In some embodiments, the mounting plate 130 covers the solder joints in the plurality of branch connection portions 121.

[0046] In the above embodiments, the fixing plate 130 directly presses against the solder joints, which serves to fix the branch connection portion 121 to prevent warpage of the branch connection portion 121 while ensuring insulation, dustproof, and waterproof effects of the solder joints.

[0047] In some embodiments, with reference to Fig. 2, the printed circuit board body 110 comprises a first main layer B1 and a second main layer B2 stacked together, and wherein the first main layer B1 is connected to a first branch structure E1, the second main layer B2 is connected to a second branch structure E2; wherein the first branch structure E1 and the second branch structure E2 are distributed on two sides of the extension direction of the printed circuit board body 110.

[0048] In the above embodiments, the first branch structure E1 and the second branch structure E2 are arranged symmetrically to reduce branch warpage. Additionally, when the first main layer B1 and the second main layer B2 are stacked together, the output ends do not need to be bent, and two output ends are arranged separately on two layers for convenient subsequent direct insertion into the connector seat 140 of the BMS (Battery Management System).

[0049] It should be noted that in some embodiments, the straight portions of the two main layers are stacked in the third direction Z, and the two branch structures 120 may be either offset or symmetrically distributed in the first direction X.

[0050] In some embodiments, with reference to Fig. 2, the first main layer B1 and the second main layer B2 are arranged between two layers of the fixing plate 130, and the total thickness of the portion between the two layers of the fixing plate 130 is represented by D, where D≤150 µm is satisfied.

[0051] In the above embodiments, a first fixing plate K1 and a second fixing plate K2 are arranged on both sides of the two main layers in the third direction Z, forming an overall laminated structure. An excessive overall thickness would take up too much space, and the sides could easily break.

[0052] In some embodiments, the first metal has an electrical conductivity greater than that of the second metal, and wherein a thickness of the first metal is represented by d1, a thickness of the second metal is represented by d2, wherein 1≤d1 / d2≤2.5 is satisfied.

[0053] In the above embodiments, the main purpose of the second metal layer is to improve the solderability between the first metal and the solder joint of the branch connection portion 121, and the second metal layer can also prevent oxidation.

[0054] If the ratio d1 / d2 is too large, this indicates that the thickness of the second metal is insufficient, resulting in insufficient efficiency. However, since the second metal has a lower conductivity than the first metal, if the ratio d1 / d2 is too small, meaning the second metal is too thick, this would impair the current flow of the conductive line 111. In some embodiments, d1 / d2 may be 1, 2, or 2.5.

[0055] It should be noted that the first metal may be flat copper having a rectangular cross-section, its thickness direction being the third direction Z, and the second metal may be a tin layer coated on the surface of the first metal.

[0056] Furthermore, in actual products, the coated tin has a thickness of 0.2 mm, and the flat copper has a thickness of 0.1 mm, which ensures that tin can overflow from the through holes a to increase the welding strength.

[0057] In some embodiments, the first metal has a higher melting point than the second metal, and 0.1≤R / W1≤2.

[0058] In the above embodiments, the second metal has a lower melting point for easier welding, and in this case, the solder joint can be made larger to reduce warpage. For example, R / W1 is preferably 0.1, 1, or 2.

[0059] In some embodiments, with reference to Fig. 3, a fuse structure g is arranged on the branch structure 120.

[0060] In the above embodiments, the fuse structure g is arranged on the branch structure 120 closer to the sensing section 122 because, when the battery temperature is too high and the electrical connection needs to be cut, the fuse structure g has a shorter response time, providing faster response and better protection.

[0061] In some embodiments, with reference to Fig. 3, a buffer arm 123 is disposed between the branch connection portion 121 and the sensing portion 122, wherein the securing structure g is disposed on the buffer arm 123, and a minimum distance between the securing structure g and the sensing portion 122 is represented by H2, where 1 mm≤H2≤25 mm is satisfied. In some embodiments, H2 may be 1 mm, 10 mm, or 25 mm.

[0062] In the above embodiments, the battery gap is caused to expand along the arrangement direction of the batteries due to battery expansion, while the size of the main body of the wiring harness is fixed, and the sensing portion 122 is welded and fixed to the battery aluminum bus bar 150, which means that the relative positions of the branch connection portion 121 and the sensing portion 122 are fixed. Therefore, by designing an S-shaped buffer arm 123 between the branch connection portion 121 and the sensing portion 122, displacement due to the deformation of the buffer arm 123 can be absorbed, thereby avoiding the risk of the branch connection portion 121 being broken due to expansion and contraction displacement of the battery.

[0063] It should be noted that the expansion and contraction direction of the battery pack during operation is from the most central point of the battery pack along the second direction Y toward both sides of the battery pack; the buffer arm 123 additionally has a curved structure.

[0064] In some embodiments, a distance between the fuse structure g and the solder joint is represented by H3 and satisfies H3≥5 mm.

[0065] In the above embodiments, if the distance between the fuse structure g and the solder joint is too close, this may cause the fuse structure g to fail during welding of the solder joint.

[0066] In some embodiments, the branch connection portion 121 is a branch structure made of FPC (also called FPC branch structure) formed by thermal printing film encapsulation, and 0.2≤R / W1≤2.

[0067] In the above embodiments, the branch formed by thermal printing film encapsulation itself has improved hardness, which reduces the likelihood of warping, so R / W1 may preferably be 0.2, 1 or 2.

[0068] In some embodiments, the circuit board body 110 is a main layer structure made of FFC (also called FFC main layer structure), and a peeling force F after the FPC branch structure and the FFC main layer structure are welded together satisfies F≥8 N.

[0069] In the above embodiments, if the peeling force is too small, it would be easy to peel the FPC branch structure from the FFC main layer structure.

[0070] In summary, in some embodiments, the present application provides a printed circuit board assembly 100 for a battery device in which FFC (i.e., tinned copper) serves as the printed circuit board body 110, FPC (i.e., etched copper wire) serves as the branching structure 120, and is then encapsulated with the mounting plate 130. The entire assembly exhibits the flexible properties of FFC while reducing production costs. Meanwhile, the fuse structure g formed by etching FPC is positioned closer to the sensing portion 122, thereby providing better safety without spark generation.In addition, the stacked main layers can be formed, such as upper and lower FFC layers, which collect from both sides of batteries and form a two-layer insertion structure to be directly inserted into the BMS, thereby reducing the overall width of the wiring harness and adapting to more internal space of battery packs.

[0071] It should be noted that the embodiments of the present application describe only the structures related to improvements in the circuit board assembly 100 for a battery device, but this does not mean that it does not include other structures. For example, the circuit board assembly 100 for the battery device also includes a connector seat 140 electrically connected to the circuit board body 110, and / or a battery aluminum bus bar 150 electrically connected to the sensing section 122, etc. Other structures will not be discussed in detail here.

[0072] In particular, the term "and / or" in the present application should be understood as follows: In the first case, the term "and / or" between a first entity and a second entity includes any of the following meanings: (1) only the first entity; (2) only the second entity; and (3) both the first entity and the second entity.

[0073] In the second case, the term "and / or" between the last two entities among three or more entities indicates that at least any one of this plurality of entities is included. For example, the phrase "first entity, second entity, and / or third entity" and the phrase "first entity and / or second entity and / or third entity" have the same meaning, specifically including the following combinations: (1) only the first entity; (2) only the second entity; (3) only the third entity; (4) the first entity and the second entity without the third entity; (5) the first entity and the third entity without the second entity; (6) the second entity and the third entity without the first entity; and (7) the first entity and the second entity and the third entity.

[0074] Furthermore, although the above content describes embodiments of the present application in conjunction with the drawings, those skilled in the art may make various modifications and alterations without departing from the concept of the present application, and such modifications and alterations all fall within the scope of the present application.

Claims

[1] A circuit board assembly for a battery device, comprising: a circuit board body (110) having a plurality of conductive lines (111) arranged in parallel, the conductive line (111) comprising a first metal and a second metal covering an outer surface of the first metal, and the second metal having a lower hardness than the first metal; a branch structure (120) comprising a branch connection portion (121) formed by the first metal and a sensing portion (122) connected to the branch connection portion (121), the sensing portion (122) being configured to collect battery information; the branch connection portion (121) comprising at least two rows of through-holes (a) along an arrangement direction of the plurality of conductive lines (111), positions of the through-holes (a) corresponding to positions of the conductive lines (111), at least one of the through-holes (a) having a solder joint therein, and the solder joint being welded to the conductive line (111); a fixing plate (130) covering a surface of the solder joint and fixedly connected to the branch connection portion (121), wherein a dimension of the fixing plate (130) along the arrangement direction of the plurality of conductive lines (111) is represented by W1, a dimension of the through-hole (a) along the arrangement direction of the plurality of conductive lines (111) is represented by R, wherein 0.01≤R / W1≤2 is satisfied. [2] The circuit board assembly for a battery device according to claim 1, wherein a distance between the conductive line (111) having the soldering point and a conductive line (111) adjacent thereto is represented by H1, satisfying 0.3 mm≤H1≤2 mm. [3] A circuit board assembly for a battery device according to claim 1 or 2, wherein each branch connection portion (121) has a plurality of rows of through holes (a) along an extending direction of the conductive line (111). [4] The circuit board assembly for a battery device according to claim 3, wherein a dimension of the branch connection portion (121) along the extending direction of the conductive line (111) is represented by L1, a number of the through holes (a) is represented by n, an area of ​​the through hole (a) is represented by S, satisfying 0.3≤L1 / (n*S)≤0.

6. [5] The circuit board assembly for a battery device according to claim 3, wherein along the extending direction of the conductive line (111), a distance between adjacent rows of the through-holes (a) is represented by P, satisfying 0.5 mm≤P≤1.5 mm. [6] The circuit board assembly for a battery device according to claim 5, wherein a thickness of the fixing plate (130) is represented by d, where d≥0.03 mm and P≤1.2 mm are satisfied. [7] The circuit board assembly for a battery device according to claim 4, wherein a dimension of the fixing plate (130) along the extending direction of the conductive line (111) is represented by L2, satisfying 0.01≤L1 / L2≤1. [8] A circuit board assembly for a battery device according to any one of the preceding claims, wherein a width of the conductive line (111) is represented by W2, satisfying 0.5 mm≤R / W2≤2 mm. [9] A circuit board assembly for a battery device according to any one of the preceding claims, wherein a thickness of the fixing plate (130) is represented by d, satisfying 0.03 mm≤d≤0.1 mm and 0.0006≤d / W1≤0.

05. [10] The circuit board assembly for a battery device according to claim 9, wherein a dimension of the branch connection portion (121) along the arrangement direction of the plurality of conductive lines (111) is represented by W2, where W2≤W1 and 0.03 mm≤d≤0.06 mm are satisfied. [11] The circuit board assembly for a battery device according to claim 9, wherein both ends of the branch connection portion (121) in a thickness direction of the branch connection portion (121) are provided with the fixing plate (130), and 0.03 mm≤d≤0.05 mm. [12] A circuit board assembly for a battery device according to any one of the preceding claims, wherein the fixing plate (130) is adhesively fixed to the branch connection portion (121) and the circuit board body (110). [13] A circuit board assembly for a battery device according to any one of the preceding claims, wherein the plurality of conductive lines (111) are respectively connected to a plurality of branch connection portions (121) in a one-to-one correspondence, and each branch connection portion (121) is welded to a corresponding conductive line (111) via the solder joint formed in the through-hole (a) corresponding to the corresponding conductive line (111). [14] A circuit board assembly for a battery device according to claim 13, wherein the fixing plate (130) covers solder joints on the plurality of branch connection portions (121). [15] A circuit board assembly for a battery device according to any one of the preceding claims, wherein the circuit board body (110) comprises a first main layer (B1) and a second main layer (B2) stacked together, and wherein the first main layer (B1) is connected to a first branch structure (E1), wherein the second main layer (B2) is connected to a second branch structure (E2); and wherein the first branch structure (E1) and the second branch structure (E2) are distributed on two sides of an extending direction of the circuit board body (110). [16] The circuit board assembly for a battery device according to claim 15, wherein the first main layer (B1) and the second main layer (B2) are arranged between two layers of the fixing plate (130), and wherein a total thickness of a portion between the two layers of the fixing plate (130) is represented by D, satisfying D≤150 µm. [17] The circuit board assembly for a battery device according to any one of the preceding claims, wherein the first metal has a greater electrical conductivity than that of the second metal, a thickness of the first metal being represented by d1 and a thickness of the second metal being represented by d2, wherein 1≤d1 / d2≤2.5 is satisfied. [18] A circuit board assembly for a battery device according to any preceding claim, wherein the first metal has a higher melting point than that of the second metal, and 0.1≤R / W1≤2. [19] A circuit board assembly for a battery device according to any one of the preceding claims, wherein a fuse structure (g) is arranged on the branch structure (120). [20] The circuit board assembly for a battery device according to claim 19, wherein a buffer arm (123) is disposed between the branch connection portion (121) and the sensing portion (122), the fuse structure (g) is disposed on the buffer arm (123), and a minimum distance between the fuse structure (g) and the sensing portion (122) is represented by H2, satisfying 1 mm≤H2≤25 mm. [21] The circuit board assembly for a battery device according to claim 20, wherein a distance between the fuse structure (g) and the soldering point is represented by H3, satisfying H3≥5 mm. [22] A circuit board assembly for a battery device according to any preceding claim, wherein the branch connection portion (121) is an FPC branch structure formed by thermal printing film encapsulation, satisfying 0.2≤R / W1≤2. [23] The circuit board assembly for a battery device according to claim 22, wherein the circuit board body (110) is an FFC main layer structure, and a peeling force after the FPC branch structure and the FFC main layer structure are welded is represented by F, satisfying F≥8 N.

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