Circuit board and battery pack
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- MURATA MFG CO LTD
- Filing Date
- 2024-10-18
- Publication Date
- 2026-06-16
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
Technical Field
[0001] This technology relates to a circuit board and a battery pack.
Background Art
[0002] A battery pack is provided with a circuit board that controls the charging and discharging of a plurality of batteries incorporated in the battery pack (see, for example, Patent Document 1).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] By the way, electronic components such as ICs mounted on a circuit board may be coated with a waterproof resin to prevent deterioration due to moisture contained in the outside air or water wetting. Such a waterproof resin is formed, for example, in the manufacturing process by sandwiching the circuit board with a mold, plasticizing solid resin pellets in a melting furnace into a liquid, injecting the liquid from a gate into the mold, and curing the liquid resin in the mold by cooling. When such a waterproof resin is formed by mold molding, when the linear expansion coefficient of the electronic component molded with the waterproof resin is very large compared to the linear expansion coefficient of the waterproof resin, when the electronic component expands and contracts due to a cold and heat cycle or the like, stress concentration may occur at the waterproof resin covering the expanded and contracted electronic component or at the interface between the expanded and contracted electronic component and the waterproof resin. In this case, there is a problem that the waterproof resin peels off from the circuit board or the like, and the waterproof by the waterproof resin fails. Provided are a circuit board and a battery pack capable of suppressing the failure of waterproofing by the waterproof resin.
[0005] The circuit board relating to the first aspect of this technology comprises a wiring board having a first main surface, a plurality of electronic components mounted on the first main surface, and a resin part covering the plurality of electronic components. The plurality of electronic components include a first component mainly composed of resin and a second component mainly composed of metal. The resin part is made of one type of resin material. The resin part has a first resin part that covers the surface of the first component and a second resin part that covers the surface of the second component. In the first resin part, the maximum thickness of the portion covering the top surface of the first component is t1, and the maximum thickness of the portion covering the side surface of the first component is t2. In the second resin part, the maximum thickness of the portion covering the top surface of the second component is t3, and the maximum thickness of the portion covering the side surface of the second component is t4. In this case, t1 to t4 satisfy the following equations (1) to (4). Circuit board. t1 > t3 ... (1) t1 > t4 ... (2) t2 > t3 ... (3) t2 > t4 ... (4)
[0006] The battery pack relating to the second aspect of this technology includes a circuit board that controls the charging and discharging of one or more batteries. The circuit board has a configuration common to the circuit board relating to the first aspect described above. [Effects of the Invention]
[0007] In the circuit board relating to the first aspect of this technology, and in the battery pack relating to the second aspect of this technology, a first component mainly composed of resin and a second component mainly composed of metal are covered by a resin part made of a single type of resin material. The thickness (maximum thickness t1, maximum thickness t2) of the first resin part covering the surface of the first component, and the thickness (maximum thickness t3, maximum thickness t4) of the second resin part covering the surface of the second component, satisfy the above equations (1) to (4). As a result, even in environments with large temperature differences, the expansion of the first component is suppressed by the first resin part. Consequently, the adhesion between the first resin part and the wiring board is maintained, and the intrusion of water between the first resin part and the wiring board is suppressed. [Brief explanation of the drawing]
[0008] [Figure 1] Figure 1 is a diagram showing an example of a planar configuration of a circuit board according to one embodiment of this technology. [Figure 2] Figure 2 shows an example of the planar configuration of the wiring board shown in Figure 1. [Figure 3] Figure 3(A) shows an example of the cross-sectional configuration of the circuit board in Figure 1 along line AA. Figure 3(B) shows an example of the planar configuration of the circuit board in Figure 1, specifically the portion including line AA. [Figure 4] Figure 4 is an enlarged view of the cross-sectional configuration shown in Figure 3(A). [Figure 5] Figures 5(A), 5(B), and 5(C) are diagrams that explain the design concept for the thickness of the resin part in Figure 1. [Figure 6] Figure 6 shows an example of simulation results regarding the relationship between the thickness of the molded resin and the amount of deformation of components when a circuit board, in which resin and metal components are covered with molded resin, is subjected to a temperature change from -40°C to +85°C. [Figure 7] Figure 7(A) shows an example of the cross-sectional configuration of the circuit board shown in Figure 1 along line AA when the circuit board is placed in an environment of -40°C. Figure 7(B) shows an example of the cross-sectional configuration of the circuit board shown in Figure 1 along line AA when the circuit board is placed in an environment of -40°C to +85°C. [Figure 8] Figure 8(A) shows an example of the cross-sectional configuration of the circuit board of the comparative example when it is placed in an environment of -40°C. Figure 8(B) shows an example of the cross-sectional configuration of the circuit board of the comparative example when it is placed in an environment of -40°C to +85°C. [Figure 9] Figure 9(A) shows an example of the planar configuration of the lower mold. Figure 9(B) shows an example of the cross-sectional configuration of the lower mold in Figure 9(A) along line AA. [Figure 10] Figure 10(A) shows an example of the planar configuration of the upper mold. Figure 10(B) shows an example of the cross-sectional configuration of the upper mold in Figure 10(A) along line AA. [Figure 11] Figure 11 is a diagram illustrating an example of the manufacturing procedure for the circuit board shown in Figure 1. [Figure 12] FIG. 12 is a diagram showing a modified example of the planar configuration of the circuit board of FIG. 1. [Figure 13] FIG. 13 is a diagram showing a modified example of the perspective configuration of the first resin portion of FIG. 3(B). [Figure 14] FIG. 14 is a diagram showing a cross-sectional configuration example taken along line A-A of the first resin portion of FIG. 13. [Figure 15] FIG. 15 is a diagram showing a modified example of the cross-sectional configuration taken along line A-A of the circuit board of FIG. 1. [Figure 16] FIG. 16 is a diagram showing a perspective configuration example of the first resin portion of FIG. 15. [Figure 17] FIG. 17 is a diagram showing a modified example of the cross-sectional configuration taken along line A-A of the circuit board of FIG. 1. [Figure 18] FIG. 18 is a diagram showing a modified example of the cross-sectional configuration taken along line A-A of the circuit board of FIG. 1. [Figure 19] FIG. 19 is a diagram showing a perspective configuration example of the battery pack. [Figure 20] FIG. 20 is a diagram showing a perspective configuration example of the battery module which is the content of the battery pack of FIG. 19. [Figure 21] FIG. 21 is a diagram showing a developed perspective configuration example of the battery pack of FIG. 19.
Embodiments for Carrying Out the Invention
[0009] Hereinafter, embodiments for carrying out the present technology will be described in detail with reference to the drawings.
[0010] (Embodiment) First, the circuit board 100 according to an embodiment of the present technology will be described. FIG. 1 shows a planar configuration example of the circuit board 100. As shown in FIG. 1, the circuit board 100 includes a wiring board 10 having a first main surface 11. The circuit board 100 further includes a plurality of electronic components mounted on the first main surface 11.
[0011] The multiple electronic components 20 mounted on the first main surface 11 include, for example, at least one of the following: a microcontroller, an integrated circuit (IC), a fuse, a power busbar, a resistor, and a capacitor. On the first main surface 11, at least two of the following components are mounted as multiple electronic components: a microcontroller, an IC, a fuse, a power busbar, a resistor, and a capacitor. The wiring board 10 corresponds to one specific example of a "wiring board" according to one embodiment of this technology.
[0012] The circuit board 100 includes a plurality of resin components 20 and a plurality of metal components 30 as multiple electronic components mounted on the first main surface 11, as shown in Figure 1. Each resin component 20 is an electronic component mainly composed of resin, and is an electronic component in which the volume occupancy rate of the resin material is higher than that of the other materials. Each resin component 20 is, for example, an electronic component in which the package material is made of resin material. Each metal component 30 is an electronic component mainly composed of metal, and is an electronic component in which the volume occupancy rate of the metal material is higher than that of the other materials. Each metal component 30 is, for example, an electronic component in which the outermost surface material is made of metal material. The resin component 20 corresponds to one specific example of the "first component" according to one embodiment of the present technology. The metal component 30 corresponds to one specific example of the "second component" according to one embodiment of the present technology.
[0013] The circuit board 100 further includes a resin portion 40 that is in contact with only a part of the first main surface 11, rather than the entire first main surface 11, as shown in Figure 1. The resin portion 40 in contact with the first main surface 11 corresponds to a specific example of the "resin portion" according to one embodiment of this technology. The resin portion 40 covers the above-mentioned plurality of electronic components (specifically, a plurality of resin components 20 and a plurality of metal components 30) and is connected in a continuous manner. The resin portion 40 is made of a waterproof resin material capable of protecting the above-mentioned plurality of electronic components from moisture in the atmosphere and from submersion of the circuit board 100 in water. The resin portion 40 is made of one type of resin material, for example, one type of resin selected from the group consisting of polyamide, polyester, and polyurethane.
[0014] The wiring board 10 is a plate-shaped component in which conductive metal is formed as wiring on an insulating substrate, and is a printed wiring board (PWB) in which the above-mentioned plurality of electronic components are not mounted. The wiring board 10 may be a plate-shaped component in which wiring is formed on the surface of a single insulating substrate, or it may be a plate-shaped component in which wiring is formed on the surface and inside of a laminate formed by stacking a plurality of insulating substrates. The first main surface 11 of the wiring board 10 includes a continuous covered area S1 covered by the resin part 40 and an uncovered area S2 not covered by the resin part 40. As shown in Figure 2, the first main surface 11 of the wiring board 10 includes a mounting area S3 in which the above-mentioned plurality of electronic components are mounted and a non-mounted area S4 in which the above-mentioned plurality of electronic components are not mounted. Figure 2 shows an example of the planar configuration of the first main surface 11 of the wiring board 10.
[0015] Multiple pad electrodes are provided in the mounting area S3 for electrically connecting the multiple electronic components and the wiring of the wiring board 10. In the non-mounted area S4, the above-mentioned pad electrodes are not formed, and the surface of the insulating substrate, or a thin film covering the surface of the insulating substrate, is exposed. In a plan view, the resin portion 40 extends from the gate portion 44 in contact with the edge of the wiring board 10, through the multiple mounting areas S3, to the non-mounted area S4.
[0016] Figure 3(A) shows an example of the cross-sectional configuration of the circuit board 100 in Figure 1 along line AA. Figure 3(B) shows an example of the planar configuration of the circuit board 100 in Figure 1, specifically the portion including line AA. Figure 4 is an enlarged view of the cross-sectional configuration shown in Figure 3(A). The resin part 40 is a resin mold formed by low-pressure molding using a mold, and has a three-dimensional shape corresponding to the shape of the recess 221 of the upper mold 220, which will be described later. Here, "low-pressure molding" refers to molding at 90°C to 240°C at 3 kgf / cm². 2 ~50 kgf / cm² 2 This refers to molding under those conditions.
[0017] The resin part 40 has a first resin part 41 that covers the surface of the resin component 20 and a second resin part 42 that covers the surface of the metal component 30. The first resin part 41 is in contact with the top surface 20a and side surface 20b of the resin component 20 and is also in contact with the first main surface 11 (non-mounted area S4) of the wiring board 10. The second resin part 42 is in contact with the top surface 30a and side surface 30b of the metal component 30 and is also in contact with the first main surface 11 (non-mounted area S4) of the wiring board 10. The resin part 40 further has a third resin part 43 between the first resin part 41 and the second resin part 42 that connects the first resin part 41 and the second resin part 42. The third resin part 43 is in contact with the first main surface 11 (non-mounted area S4) of the wiring board 10.
[0018] In the first resin part 41, the maximum thickness of the portion covering the resin part 20 is set to t1. The maximum thickness t1 corresponds to the maximum thickness in the first resin part 41 from the top surface 20a of the resin part 20 to the outer surface 41a of the first resin part 41 that faces the top surface 20a of the resin part 20. In the first resin part 41, the maximum thickness of the portion covering the resin part 20 is set to t2. The maximum thickness t2 corresponds to the maximum thickness in the first resin part 41 from the side surface 20b of the resin part 20 to the outer surface 41a of the resin part 20 that faces the side surface 20b of the resin part 20. In the second resin part 42, the maximum thickness of the portion covering the metal part 30 is set to t3. The maximum thickness t3 corresponds to the maximum thickness in the second resin part 42 from the top surface 30a of the metal part 30 to the outer surface 42a of the second resin part 42 that faces the top surface 30a of the metal part 30. In the second resin part 42, the maximum thickness of the portion covering the side surface 30b of the metal part 30 is denoted as t4. The maximum thickness t4 corresponds to the maximum thickness in the second resin part 42 from the side surface 30b of the metal part 30 to the surface of the outer surface 42a of the second resin part 42 that faces the side surface 30b of the metal part 30. In this case, the maximum thicknesses t1 to t4 satisfy the following equations (1) to (4). When the maximum thicknesses t1 to t4 satisfy the following equations (1) to (4), the thickness of the first resin part 41 covering the resin part 20 is greater than the thickness of the second resin part 42 covering the metal part 30. The technical basis for the thickness of the first resin part 41 covering the resin part 20 and the thickness of the second resin part 42 covering the metal part 30 will be described in detail later. t1 > t3 ... (1) t1 > t4 ... (2) t2 > t3 ... (3) t2 > t4 ... (4)
[0019] In this specification, "facing each other" is a concept that includes not only cases where the outer surface of the resin part 40 and the top surface of the electronic component (resin part 20 or metal part 30) face each other directly, but also cases where they face each other at an angle in the direction normal to the top surface of the electronic component (resin part 20 or metal part 30) (height direction). Furthermore, in this specification, "facing each other" is a concept that includes not only cases where the outer surface of the resin part 40 and the side surface of the electronic component (resin part 20 or metal part 30) face each other directly, but also cases where they face each other at an angle in the direction normal to the side surface of the electronic component (resin part 20 or metal part 30) (lateral direction).
[0020] Let T1 be the maximum height of the first resin part 41 as viewed from the first main surface 11. Let T2 be the maximum height of the second resin part 42 as viewed from the first main surface 11. Let T3 be the maximum height of the third resin part 43 as viewed from the first main surface 11. In this case, the maximum heights T1 to T3 satisfy the following equations (5) and (6). When the maximum heights T1 to T3 satisfy the following equations (5) and (6), a groove 45 is formed in the resin part 40, with a part of the outer surface 41a of the first resin part 41 that covers the side surface 20b of the resin part 20 and a part of the outer surface 42a of the metal part 30 that covers the side surface 30b of the metal part 30 as its inner walls, and the surface of the third resin part 43 as its bottom surface. The maximum height T3 corresponds to the height from the first main surface 11 to the bottom surface of the groove 45 and satisfies the following equation (7). T3 <T1…(5) T3 <T2…(6) T3 <t1…(7)
[0021] Figures 5(A), 5(B), and 5(C) illustrate the design concept for the thickness of the resin part 40. The resin part 40 must include, for example, a base layer L1 having a resin thickness (UL certified thickness t_ul) as defined by UL (Underwriters Laboratories) certification, as shown in Figure 5(A). At this time, the presence of the resin part 20 and the metal part 30 is not considered. The resin part 40 further includes a protective layer L2 of a predetermined thickness tx that covers the resin part 20, as shown in Figure 5(B). The thickness tx is a thickness corresponding to the magnitude of the linear expansion coefficient of the resin part 20. The resin part 40 further includes a protective layer L3 of a predetermined thickness ty that covers the metal part 30, as shown in Figure 5(C). The thickness ty is a thickness corresponding to the magnitude of the linear expansion coefficient of the metal part 30. Here, the linear expansion coefficient of the resin part 20 is greater than that of the metal part 30, for example, approximately four times that of the metal part 30. Therefore, the thickness tx of the resin part 20 is approximately four times the thickness ty of the metal part 30. The resin part 40 is composed of a composite layer of a base layer L1, a protective layer L2, and a protective layer L3, as shown by the thick line in Figure 5(C), for example. As a result, the resin part 40 is a layer having a groove 45 between the resin part 20 and the metal part 30, and having a maximum thickness of t1 to t4.
[0022] The coefficient of linear expansion of the resin part 40 is smaller than that of the resin component 20. As a result, when a temperature change occurs while the resin component 20 is not covered by the resin part 40, the displacement of the resin part 40 is smaller than the displacement of the resin component 20. Consequently, when a temperature change occurs while the resin component 20 is covered by the resin part 40, the displacement of the resin component 20 is suppressed by the resin part 40. If the resin part 40 also displaces in accordance with the displacement of the resin component 20, when the temperature changes from high to low, the resin part 40 may maintain its shape at high temperature, potentially creating a large void between the resin part 40 and the resin component 20. If such a void occurs, the thickness of the portion of the resin part 40 that covers the resin component 20 will remain thin, increasing the likelihood that the resin part 40 will delaminate from the first main surface 11 with repeated heating and cooling. On the other hand, if the displacement of the resin component 20 is suppressed by the resin part 40, the possibility of such a void occurring is low, and even with repeated heating and cooling, the resin part 40 will not be more likely to delaminate from the first main surface 11.
[0023] Furthermore, the difference in the coefficients of linear expansion between the resin part 40 and the resin component 20 is greater than the difference in the coefficients of linear expansion between the resin part 40 and the metal component 30. This allows the displacement of the resin part 40 to be brought closer to the displacement of the metal component 30 when a temperature change occurs while the metal component 30 is covered by the resin part 40. In the case of the metal component 30, the displacement due to heating and cooling is very small compared to the resin component 20. Therefore, even if the displacement of the resin part 40 is brought closer to the displacement of the metal component 30, the possibility of the aforementioned void forming is low. As a result, even if heating and cooling are repeated, the resin part 40 will not be prone to peeling off from the first main surface 11.
[0024] Figure 6 shows an example of a simulation result of the relationship between the thickness of the molded resin and the amount of deformation of the components when a circuit board in which resin components 20 and metal components 30 are covered with molded resin is subjected to a temperature change from -40°C to +85°C. In this simulation, the coefficient of linear expansion of the resin component 20 is set to 70.0 × 10⁻⁶. -6 Let / K be the coefficient of thermal expansion of metal part 30 be 17.7 × 10 -6 Let / K be used, and the coefficient of thermal expansion of the molding resin be 26.0 × 10⁻⁶. -6The value was set to / K. Figures 7(A) and 7(B) show the structure in this simulation. The thickness obtained by subtracting the thickness ta1 of the resin part 20 at -40°C from the thickness ta2 of the resin part 20 at +85°C (ta2-ta1) corresponds to the amount of deformation of the part in Figure 6. Also, the thickness obtained by subtracting the thickness tb1 of the metal part 30 at -40°C from the thickness tb2 of the metal part 30 at +85°C (tb2-tb1) corresponds to the amount of deformation of the part in Figure 6.
[0025] Figure 6 shows that when the resin part 20 and metal part 30 are not covered with molding resin (molding resin thickness = 0 μm), the resin part 20 deforms by 9.0 μm and the metal part 30 deforms by 2.0 μm. On the other hand, when the resin part 20 and metal part 30 are covered with molding resin with a thickness of 0.5 μm, the resin part 20 deforms by 3.0 μm and the metal part 30 deforms by 0.5 μm. Furthermore, when the resin part 20 and metal part 30 are covered with molding resin with a thickness of 1.0 μm, the resin part 20 deforms by 0.8 μm and the metal part 30 deforms by 0.4 μm. Furthermore, when the resin part 20 and metal part 30 are covered with molding resin with a thickness of 1.5 μm, the resin part 20 deforms by 0.5 μm and the metal part 30 deforms by 0.3 μm. Furthermore, when the resin part 20 and the metal part 30 are covered with a molding resin with a thickness of 2.0 μm, the resin part 20 deforms by 0.2 μm, and the metal part 30 deforms by 0.2 μm.
[0026] When the temperature is changed from -40°C to +85°C, deformation of the resin part 20 and metal part 30 may cause, for example, the delamination of the resin part 40 (molded resin) at locations prone to stress concentration (target locations P1, P2), as shown in Figure 7(B). However, if the amount of deformation of the resin part 20 and metal part 30 can be kept to 0.5 μm or less, the adhesion force of the resin part 40 (molded resin) to the wiring board 10 (first main surface 11) can reliably prevent the resin part 40 (molded resin) from peeling off from the wiring board 10 (first main surface 11).
[0027] Figure 8(A) shows an example of the cross-sectional configuration of the circuit board of the comparative example when it is placed in an environment of -40°C. Figure 8(B) shows an example of the cross-sectional configuration of the circuit board of the comparative example when the circuit board of Figure 8(A) is moved from an environment of -40°C to an environment of +85°C. In the circuit board of the comparative example, for example, as shown in Figures 8(A) and 8(B), resin parts 110 and metal parts 120 are mounted on the surface S, and the resin parts 110 and metal parts 120 mounted on the surface S are covered by a resin layer 130. The thickness obtained by subtracting the thickness ta3 of the resin part 110 at -40°C from the thickness ta4 of the resin part 110 at +85°C (ta4-ta3) corresponds to the amount of deformation of the resin part 110. Furthermore, the thickness obtained by subtracting the thickness tb3 of the metal part 120 at -40°C from the thickness tb4 of the metal part 120 at +85°C (tb4-tb3) corresponds to the amount of deformation of the metal part 120.
[0028] In the circuit board of the comparative example, the thickness of the resin layer 130 is generally uniform at -40°C, but at +85°C, the resin layer 130 bulges significantly due to the expansion of the resin component 110. This significant bulging of the resin layer 130 due to the expansion of the resin component 110 causes stress concentration at the target location P4. Furthermore, the expansion of the resin component 110 pulls the end of the resin layer 130 closer to the metal component 120 (target location P5) towards the resin component 110, causing stress concentration at target location P5 as well. As a result, there is a risk of delamination of the resin layer 130 at target locations P4 and P5.
[0029] By the way, comparing Figure 7(B) and Figure 8(B), there is a difference in the locations where stress concentration occurs. In Figure 7(B), the area near the side of the resin part 110 (target locations P1, P2), where the expansion amount is large, is the location where stress concentration occurs within the first resin part 41 covering the resin part 110. On the other hand, in Figure 8(B), the area near the side of the metal part 120 (target location P5), as well as the resin layer 130, is also a location where stress concentration occurs. This is because the resin layer 130 does not have grooves 45 as shown in Figure 7(B), and the stress generated within the resin layer 130 extends to the area near the side of the metal part 120 (target location P5). On the other hand, the resin part 40 has grooves 45 as shown in Figure 8(B), and the stress generated within the resin part 41 does not extend to the area near the side of the metal part 30 due to stress concentration in the grooves 45. Furthermore, as shown in Figure 7(B), even if stress concentration occurs directly below the groove 45 (target location P2) and delamination occurs directly below the groove 45 (target location P2), there is no possibility of external water entering between the resin part 40 and the first main surface 11.
[0030] Next, the manufacturing method of the circuit board 100 will be described. First, the molds (lower mold 210, upper mold 220) used in the manufacturing process of the circuit board 100 will be described, and then the manufacturing method of the circuit board 100 using the molds (lower mold 210, upper mold 220) will be described.
[0031] Figure 9(A) shows an example of the planar configuration of the lower mold 210. Figure 9(B) shows an example of the cross-sectional configuration of the lower mold 210 in Figure 9(A) along line AA. Figure 10(A) shows an example of the planar configuration of the upper mold 220. Figure 10(B) shows an example of the cross-sectional configuration of the upper mold 220 in Figure 10(A) along line AA.
[0032] The lower mold 210 has a housing portion 211 for housing the wiring board 10, as shown in Figures 9(A) and 9(B). The upper mold 220 has a recess 221, as shown in Figures 10(A) and 10(B). When the upper mold 220 is superimposed on the wiring board 10, the recess 221 is continuous with a portion of the first main surface 11 that is opposite to a continuous area to be covered, which includes a plurality of electronic components (a plurality of resin components 20 and a plurality of metal components 30).
[0033] The recess 221 has a three-dimensional shape corresponding to the shape of the resin part 40. A gate portion 222 is connected to one end of the recess 221. The gate portion 222 is a gap that connects one end of the recess 221 to the outside and serves as an inlet for pouring the uncured resin 200 (described later) into the upper mold 220.
[0034] The recess 221 includes, for example, two types of recesses 221a, 221b, and 221c of different depths, as shown in Figure 5(B). Recess 221a is a recess for forming the first resin portion 41. Recess 221b is a recess for forming the second resin portion 42. Recess 221c is a recess for forming the third resin portion 43. Recess 221c is located between recess 221a and recess 221b.
[0035] Figure 11 shows an example of the manufacturing procedure for a circuit board 100. First, a wiring board 10 on which multiple electronic components (multiple resin components 20 and multiple metal components 30) are mounted is prepared (step S101). Next, the lower mold 210 and the upper mold 220 are placed on top of the wiring board 10 (step S102). Next, uncured resin 200 is injected into the gate portion 222 of the upper mold 220, thereby flowing the uncured resin 200 into the recess 221 through the gate portion 222 (step S103). The uncured resin 200 is the raw material for the resin portion 40 and is composed of one type of thermoplastic resin material. The uncured resin 200 is composed of, for example, polyamide, polyester, or polyurethane.
[0036] Next, the uncured resin 200 is cooled and solidified in the mold (lower mold 210, upper mold 220) (step S104). As a result, the resin part 40 is formed. Finally, the mold (lower mold 210, upper mold 220) is removed from the wiring board 10. In this way, the circuit board 100 is manufactured.
[0037] Next, we will explain the effects of the circuit board 100.
[0038] In this embodiment, the resin part 20 and the metal part 30 are covered by a resin part 40 made of a single type of resin material. The thickness (maximum thickness t1, maximum thickness t2) of the first resin part 41 that covers the surface of the resin part 20, and the thickness (maximum thickness t3, maximum thickness t4) of the second resin part 42 that covers the surface of the metal part 30, satisfy the above equations (1) to (4). As a result, even in environments with large temperature differences, the expansion of the resin part 20 is suppressed by the first resin part 41. Consequently, the adhesion between the first resin part 41 and the wiring board 10 is maintained, and the intrusion of water between the first resin part 41 and the wiring board 10 is suppressed. Therefore, the failure of waterproofing by the resin part 40 can be suppressed.
[0039] In this embodiment, a third resin part 43 is provided between the first resin part 41 and the second resin part 42, connecting the first resin part 41 and the second resin part 42. The maximum height T1 of the first resin part 41, the maximum height T2 of the second resin part 42, and the maximum height T3 of the third resin part 43 satisfy the above equations (5) and (6). At this time, a groove 45 is formed in the resin part 40, with a part of the outer surface 41a of the first resin part 41 that covers the side surface 20b of the resin part 20 and a part of the outer surface 42a of the metal part 30 that covers the side surface 30b of the metal part 30 serving as the inner wall, and the surface of the third resin part 43 serving as the bottom surface. The maximum height T3 corresponds to the height from the first main surface 11 to the bottom surface of the groove 45, and satisfies the above equation (7). As a result, the stress generated within the resin part 41 due to the expansion of the resin part 20 does not extend to the vicinity of the side surface of the metal part 30 due to stress concentration in the groove 45. Furthermore, the deeper the groove 45, the easier it is for the inner wall of the groove 45 to stretch in the depth direction of the groove 45, and the stress generated within the resin part 41 due to the expansion of the resin part 20 is relieved by the stretching of the inner wall of the groove 45. As a result, the possibility of delamination of the resin part 40 (second resin part 42) near the side surface of the metal part 30 can be suppressed. Therefore, the failure of waterproofing by the resin part 40 can be suppressed.
[0040] In this embodiment, the difference in the coefficients of linear expansion between the resin part 40 and the resin component 20 is greater than the difference in the coefficients of linear expansion between the resin part 40 and the metal component 30. This allows the displacement of the resin part 40 to be brought closer to the displacement of the metal component 30 when a temperature change occurs while the metal component 30 is covered by the resin part 40. The displacement of the metal component 30 due to heating and cooling is much smaller than that of the resin component 20. Therefore, even if the displacement of the resin part 40 is brought closer to that of the metal component 30, the possibility of the above-mentioned void forming is low. As a result, even if heating and cooling are repeated, the resin part 40 will not be prone to peeling off from the first main surface 11. Thus, the failure of waterproofing by the resin part 40 can be suppressed.
[0041] In this embodiment, the coefficient of linear expansion of the resin part 40 is smaller than that of the resin component 20. As a result, when a temperature change occurs while the resin component 20 is not covered by the resin part 40, the displacement of the resin part 40 is smaller than the displacement of the resin component 20. Consequently, when a temperature change occurs while the resin component 20 is covered by the resin part 40, the displacement of the resin component 20 is suppressed by the resin part 40. If the resin part 40 also displaces in accordance with the displacement of the resin component 20, when the temperature changes from high to low, the resin part 40 may maintain its shape at high temperature, potentially creating a large cavity between the resin part 40 and the resin component 20. If such a cavity occurs, the thickness of the portion of the resin part 40 that covers the resin component 20 will remain thin, increasing the likelihood that the resin part 40 will peel off from the first main surface 11 during repeated heating and cooling cycles. On the other hand, if the displacement of the resin component 20 is suppressed by the resin part 40, the possibility of the above-mentioned void occurring is low, and even if repeated heating and cooling occurs, the resin part 40 will not easily peel off from the first main surface 11. Therefore, the failure of waterproofing by the resin part 40 can be suppressed.
[0042] Next, a modified example of the circuit board 100 will be described.
[0043] (Variation A) In the above embodiment, the resin part 40 does not necessarily have an overhang on its side corresponding to the base layer L1 having a resin thickness (UL certified thickness t_ul), as shown in Figure 12, for example. Even in this case, the failure of waterproofing by the resin part 40 can be suppressed, similar to the above embodiment.
[0044] (Torture B) Figure 13 shows a modified example of the perspective view configuration of the first resin part 41. Figure 14 shows an example of the cross-sectional configuration of the first resin part 41 along line AA in Figure 13. In the above embodiment and modified example A, the first resin part 41 may have radial protrusions 46 in the portion facing the top surface 20a of the resin part 20, for example, as shown in Figures 13 and 14. The radial protrusions 46 have a shape in which multiple locations covering each corner portion 20c of the top surface 20a of the resin part 20 are connected diagonally.
[0045] In the first resin part 41, the minimum thickness of the portion covering each corner portion 20c of the top surface 20a of the resin part 20 is set to t5. The minimum thickness t5 corresponds to the minimum thickness in the first resin part 41 from each corner portion 20c of the top surface 20a of the resin part 20 to the surface of the outer surface 41a of the first resin part 41 that is opposite to each corner portion 20c. In the first resin part 41, the minimum thickness of the portion covering the top surface 20a of the first resin part 41 is set to t6. The minimum thickness t6 corresponds to the minimum thickness in the first resin part 41 from the top surface 20a of the first resin part 41 to the surface of the outer surface 41a of the first resin part 41 that is opposite to the top surface 20a. In this case, t5 and t6 satisfy the following equation (8). t5 > t6 ... (8)
[0046] In the first resin part 41, the portion covering each corner portion 20c of the top surface 20a of the resin component 20 experiences the greatest displacement when the resin component 20 expands and contracts compared to other parts of the first resin part 41. In this modified example, radial protrusions 46 are provided in the portion of the first resin part 41 where the greatest displacement occurs when the resin component 20 expands and contracts compared to other parts of the first resin part 41. As a result, the displacement of the resin component 20 is suppressed by the radial protrusions 46. Consequently, the adhesion between the first resin part 41 and the wiring board 10 is maintained, preventing water from entering between the first resin part 41 and the wiring board 10. Therefore, the failure of the waterproofing provided by the resin part 40 can be suppressed.
[0047] (Extreme C) Figure 15 shows a modified example of the cross-sectional configuration of the first resin part 41 in Figure 1 along line AA. Figure 16 shows an example of the perspective view configuration of the first resin part 41 in Figure 15. In the above embodiment and modified example A, the first resin part 41 may have an annular protrusion 47 that is thicker at the edges and side surfaces 20b of the top surface 20a of the resin part 20 than at the central portion of the top surface 20a of the resin part 20, as shown in Figures 15 and 16.
[0048] In the first resin part 41, the minimum thickness of the portion covering each corner portion 20c of the top surface 20a of the resin part 20 is set to t5. The minimum thickness t5 corresponds to the minimum thickness in the first resin part 41 from each corner portion 20c of the top surface 20a of the resin part 20 to the surface of the outer surface 41a of the first resin part 41 that is opposite to each corner portion 20c. In the first resin part 41, the minimum thickness of the portion covering the top surface 20a of the first resin part 41 is set to t6. The minimum thickness t6 corresponds to the minimum thickness in the first resin part 41 from the top surface 20a of the first resin part 41 to the surface of the outer surface 41a of the first resin part 41 that is opposite to the top surface 20a. In this case, t5 and t6 satisfy the following equation (8). t5 > t6 ... (8)
[0049] In the first resin part 41, the minimum thickness of the portion covering the edge portion of the top surface 20a of the resin part 20 is set to t5. The minimum thickness t5 corresponds to the minimum thickness in the first resin part 41 from the corner portion 20c of the top surface 20a of the resin part 20 to the surface of the outer surface 41a of the first resin part 41 that faces the edge portion of the top surface 20a. In the first resin part 41, the minimum thickness of the portion covering the central portion of the top surface 20a of the resin part 20 is set to t6. The minimum thickness t6 corresponds to the minimum thickness in the outer surface 41a of the first resin part that faces the surface of the top surface 20a of the resin part 20 to the surface of the outer surface 41a of the first resin part that faces the central portion of the top surface 20a of the resin part 20. The minimum thickness of the portion covering the side surface 20b of the resin part 20 is set to t7. The minimum thickness t7 corresponds to the minimum thickness from the side surface 20b of the resin part 20 to the outer surface 41a of the first resin part 41 that faces the side surface 20b of the resin part 20. In this case, t5 to t7 satisfy the following equations (9) and (10). t5 > t6 ... (9) t7 > t6 ... (10)
[0050] In the first resin part 41, the portion covering each corner portion 20c of the top surface 20a of the resin component 20 experiences the greatest displacement when the resin component 20 expands and contracts compared to other parts of the first resin part 41. In this modified example, an annular protrusion 47 is provided at the portion of the first resin part 41 where the greatest displacement occurs when the resin component 20 expands and contracts compared to other parts of the first resin part 41. As a result, the displacement of the resin component 20 is suppressed by the annular protrusion 47. Consequently, the adhesion between the first resin part 41 and the wiring board 10 is maintained, preventing water from entering between the first resin part 41 and the wiring board 10. Therefore, the failure of the waterproofing provided by the resin part 40 can be suppressed.
[0051] (Variation D) Figure 17 shows a modified example of the cross-sectional configuration of the first resin part 41 along line AA in Figure 1. In the above embodiments and modified examples A to C, for example, as shown in Figure 17, the third resin part 43 may be omitted, and the first resin part 41 and the second resin part 42 may be directly connected to each other. In this case, the resin part 40 has a first side surface 41d, which is a part of the outer surface 41a of the first resin part 41 that covers the side surface 20b of the resin part 20, and a second side surface 42d, which is a part of the outer surface 42a of the second resin part 42 that covers the side surface 30b of the metal part 30, as its inner surface, and a groove 48 is formed in the resin part 40 where the thickness T4 from the first main surface 11 is locally thin at the location where the first side surface 41d and the second side surface 42d are in contact with each other.
[0052] The groove 48 has a V-shaped cross-section, for example, as shown in Figure 17. The first side surface 41d and the second side surface 42d may both be flat inclined surfaces, for example, as shown in Figure 17. The groove 48 may have a U-shaped cross-section, for example, as shown in Figure 18. In this case, the groove 48 has a curved inclined surface, for example, as shown in Figure 18. The thickness T4 satisfies the following equation (11). T4 <t1…(11)
[0053] In this modified example, a groove 48 is formed with the first side surface 41d of the first resin part 41 and the second side surface 42d of the second resin part 42 as its inner walls. At this time, the thickness T4 related to the depth of the groove 48 satisfies equation (11). In this way, by providing a groove 48 without a flat bottom surface to the resin part 40, the stress generated in the resin part 41 due to the expansion of the resin part 20 is locally concentrated in the groove 48 where the first side surface 41d and the second side surface 42d are in contact with each other. As a result, compared to the case where a groove 45 with a flat bottom surface is provided to the resin part 40, the stress generated in the resin part 41 due to the expansion of the resin part 20 is less likely to reach the vicinity of the side surface of the metal part 30 due to stress concentration in the groove 48. As a result, the possibility of delamination of the resin part 40 (second resin part 42) near the side surface of the metal part 30 can be suppressed. Therefore, the failure of waterproofing by the resin part 40 can be suppressed.
[0054] (Examples of application) Figure 19 shows an example of a perspective view of a battery pack 1000 equipped with a circuit board 100 (hereinafter simply referred to as "circuit board 100") according to the above embodiment and modified examples A to D. Figure 20 shows an example of a perspective view of the battery module 300 and the circuit board 100, which are housed in the battery pack 1000. Figure 21 shows an example of an unfolded perspective view of the battery pack 1000.
[0055] The battery pack 1000 comprises, for example, an outer case 400, a battery module 300 housed in the outer case 400, and a circuit board 100, as shown in Figures 19 and 20. The battery module 300 has, for example, one or more batteries 310, a plurality of battery holders 320, and a plurality of metal tabs 330, as shown in Figure 21. The circuit board 100 is connected to, for example, the plurality of metal tabs 330 and functions as a control board that controls the charging and discharging of one or more batteries 310. The circuit board 100 may have circuits for, for example, measuring the voltage of one or more batteries 310, detecting the remaining capacity of one or more batteries 310, and measuring the current output from one or more batteries 310 to detect the presence or absence of overcurrent.
[0056] The outer casing 400 is composed of a lower case 420 and an upper case 430, as shown in Figure 21, for example. The lower case 420 and the upper case 430 are stacked on top of each other to form a housing space for the battery module 300 and the circuit board 100. The outer casing 400 (for example, the lower case 420) is provided with an external terminal 410 connected to the circuit board 100. The battery module 300 is connected to the external terminal 410 via the circuit board 100.
[0057] In this application example, the circuit board 100 according to the above embodiment and modified versions A to D is used in the battery pack 1000. This makes it possible to suppress the deterioration of multiple electronic components (multiple resin components 20 and multiple metal components 30) of the circuit board 100 due to humidity in the atmosphere, thereby providing a battery pack 1000 with high resistance to humidity in the atmosphere.
[0058] Although the present technology has been described above with reference to one embodiment, the present technology is not limited to the embodiments described above, and various modifications are possible. The effects described herein are merely illustrative, and therefore the effects of the present technology are not limited to those described herein. Accordingly, other effects may be obtained with respect to the present technology. [Explanation of Symbols]
[0059] 10...Wiring board, 11...First main surface, 20...Resin part, 20a...Top surface, 20b...Side surface, 30...Metal part, 30a...Top surface, 30b...Side surface, 40...Resin part, 41...First resin part, 41a...Outer surface, 41d...First side surface, 42d...Second side surface, 42...Second resin part, 42a...Outer surface, 43...Third resin part, 44...Gate part, 45...Groove part, 46...Radial protrusion, 47...Annular protrusion, 48...Groove part, 100...Circuit board, 110...Resin part, 120...Metal part, 130...Resin layer, 200...Uncured resin, 210...Lower mold, 211...Housing part, 220...Upper mold, 221...Recess, 2 22...Gate section, 300...Battery module, 310...Battery, 320...Battery holder, 330...Metal tab, 400...Outer case, 410...External terminal, 420...Lower case, 430...Upper case, 1000...Battery pack, L1...Base layer, L2,L3...Protective layer, P1,P2,P3,P4,P5...Target area, S...Surface, S1...Coated area, S2...Uncoated area, S3...Mounted area, S4...Non-mounted area, t1,t2,t3,t4...Maximum thickness, t5,t6,t7,t8,t9...Minimum thickness, t_ul,ta,tb...Thickness, T1,T2,T3...Maximum height, T4...Thickness.
Claims
1. A wiring board having a first main surface, Multiple electronic components mounted on the first main surface, The resin portion covering the plurality of electronic components Equipped with, The aforementioned plurality of electronic components include a first component mainly composed of resin and a second component mainly composed of metal. The aforementioned resin part is made of one type of resin material, The resin portion comprises a first resin portion that covers the surface of the first component and a second resin portion that covers the surface of the second component. In the first resin part, the maximum thickness of the portion covering the top surface of the first component is t1, and the maximum thickness of the portion covering the side surface of the first component is t2. In the second resin part, when the maximum thickness of the portion covering the top surface of the second part is t3 and the maximum thickness of the portion covering the side surface of the second part is t4, t1 to t4 satisfy the following equations (1) to (4) Circuit board. t1 > t3 ... (1) t1 > t4 ... (2) t2 > t3 ... (3) t2 > t4 ... (4)
2. The resin portion further includes a third resin portion between the first resin portion and the second resin portion, which connects the first resin portion and the second resin portion. When T1 is the maximum height of the first resin part as seen from the first main surface, T2 is the maximum height of the second resin part as seen from the first main surface, and T3 is the maximum height of the third resin part as seen from the first main surface, T1 to T3 satisfy the following equations (5) and (6). The circuit board according to claim 1. T3 < T1 ... (5) T3 < T2 ... (6)
3. The resin portion has a groove formed in it, with a portion of the outer surface of the first resin portion that covers the side of the first component and a portion of the outer surface of the second resin portion that covers the side of the second component forming the inner wall, and the surface of the third resin portion forming the bottom surface. The circuit board according to claim 2.
4. The T3 corresponds to the height from the first main surface to the bottom surface of the groove, and satisfies the following equation (7). The circuit board according to claim 3. T3 < t1 ... (7)
5. The resin portion has a first side surface, which is a part of the outer surface of the first resin portion that covers the side of the first component, and a second side surface, which is a part of the outer surface of the second resin portion that covers the side of the second component, as its inner surface. A groove is formed in the resin portion where the thickness T4 from the first main surface is locally thin at the location where the first side surface and the second side surface are in contact with each other. The circuit board according to claim 1.
6. T4 satisfies the following equation (7) The circuit board according to claim 5. T4 < t1 ... (7)
7. In the first resin part, when the minimum thickness of the portion covering each corner of the top surface of the first part is t5 and the minimum thickness of the portion covering the top surface of the first part is t6, then t5 and t6 satisfy the following equation (8): The circuit board according to claim 1. t5 > t6 ... (8)
8. In the first resin part, when the minimum thickness of the portion covering the edge portion of the top surface of the first part is t5, the minimum thickness of the portion covering the central portion of the top surface of the first part is t6, and the minimum thickness of the portion covering the side surface of the first part is t7, then t5 to t7 satisfy the following equations (9) and (10). The circuit board according to claim 1. t5 > t6 ... (9) t7>t6...(10)
9. The first resin portion has an annular projection that is thicker in the portion that covers the edge and side of the top surface of the first component than in the portion that covers the central part of the top surface of the first component. The circuit board according to claim 1.
10. The first resin part has radial protrusions where multiple locations covering each corner of the top surface of the first part are connected diagonally. The circuit board according to claim 1.
11. The difference in the coefficient of thermal expansion between the resin part and the first component is greater than the difference in the coefficient of thermal expansion between the resin part and the second component. The circuit board according to claim 1.
12. The resin portion is composed of one resin selected from the group consisting of polyamide, polyester, and polyurethane. The circuit board according to claim 1.
13. A circuit board for controlling the charging and discharging of one or more batteries comprises the circuit board described in any one of claims 1 to 12. Battery pack.