Power Module

Abstract

The present invention discloses a power module, comprising a main housing, a power component and at least one assembly component. The main housing has at least one side wall and at least two convex ribs extending from the side wall. The power component is arranged in the main housing and is pressed against the heat dissipation structure by the side wall. The assembly component comprises a main section and two bending sections. The main section is located between the two convex ribs and comprises a central portion, at least one movable part and a peripheral portion. The central portion has a locking portion, the peripheral portion surrounds the central portion, and the movable part is connected between the central portion and the peripheral portion. The two bending sections are respectively connected to the opposite side edges of the peripheral portion and are respectively embedded in the two convex ribs. The power module of the present invention can make the substrate of the power chip therein stably contact the heat dissipation structure to avoid skewing due to incorrect locking.

Description

Technical Field

[0001] The present invention relates to an electronic module, and in particular to a power module. Background Art

[0002] In recent years, the manufacturing process technology of power semiconductors has developed rapidly, which has greatly improved the functions of electronic components. With the increase in the processing speed and current of electronic components, the heat generated by electronic components during operation has also increased. If the waste heat cannot be effectively removed, the electronic components may fail or fail to achieve optimal performance.

[0003] For power chips, the heat generated during operation will cause the structure of the power components to deform thermally, affecting the heat transfer effect, causing the temperature of the power chips to rise and reducing their lifespan. In order to effectively dissipate the heat of the power chips, some power modules are designed to be locked onto the heat dissipation structure so that the substrate of the power chip inside can stably contact the heat dissipation structure. Furthermore, if the power module is not properly locked and becomes skewed, the substrate of the power chip will not be able to contact the heat dissipation structure accurately, resulting in a decrease in heat dissipation efficiency. Summary of the invention

[0004] The present invention is directed to a power module, which can make the substrate of the power chip inside the module stably contact the heat dissipation structure to avoid being skewed due to incorrect locking.

[0005] According to an embodiment of the present invention, a power module includes a main housing and at least one assembly component. The main housing has at least one side wall and at least two ribs extending from the side wall. The assembly component includes a main section and two bending sections. The main section is located between the two ribs and includes a central portion, at least one movable part and a peripheral portion. The central portion has a locking portion, the peripheral portion surrounds the central portion, and the movable part is connected between the central portion and the peripheral portion. The two bending sections are respectively connected to the opposite side edges of the peripheral portion and are respectively embedded in the two ribs.

[0006] In the power module according to the embodiment of the present invention, each bending section is perpendicular to the main section.

[0007] In the power module according to the embodiment of the present invention, the central portion has a ring shape.

[0008] In the power module according to the embodiment of the present invention, the number of movable members is plural, and the movable members have elastic force and surround the central portion.

[0009] In the power module according to the embodiment of the present invention, the movable members are symmetrical to the center of the locking portion.

[0010] In the power module according to the embodiment of the present invention, each bending section has a plurality of holes.

[0011] In the power module according to the embodiment of the present invention, the end of the peripheral portion is buried in the side wall.

[0012] In a power module according to an embodiment of the present invention, the power module includes a power component, wherein the power component is configured in a main shell and is pressed against a heat dissipation structure by a side wall. When the locking component passes through the locking portion and resists the elastic force of the movable part to lock the assembly component to the heat dissipation structure, the power component drives the main shell to be pressed against the heat dissipation structure through the elastic force of the movable part.

[0013] In the power module according to the embodiment of the present invention, when the locking member locks the assembly component to the heat dissipation structure, the side wall is close to the heat dissipation structure and there is a gap between at least two ribs and the heat dissipation structure.

[0014] In the power module according to the embodiment of the present invention, the number of at least one assembly component is two, and the two assembly components are respectively located at two opposite sides of the main housing.

[0015] According to an embodiment of the present invention, a power module includes a main housing and at least one assembly component. The main housing has at least one side wall. The assembly component includes a main section, two first bending sections and two second bending sections. The main section includes a central portion, at least one movable part and a peripheral portion. The central portion has a locking portion, the peripheral portion surrounds the central portion, and the movable part is connected between the central portion and the peripheral portion. The two first bending sections are respectively connected to the opposite side edges of the peripheral portion, and the two second bending sections are respectively connected to the two first bending sections and embedded in the side wall.

[0016] In the power module according to the embodiment of the present invention, each first bending section is perpendicular to the main section.

[0017] In the power module according to the embodiment of the present invention, each second bending section is perpendicular to the main section.

[0018] In the power module according to the embodiment of the present invention, the central portion has a ring shape.

[0019] In the power module according to the embodiment of the present invention, the number of movable members is plural, and the movable members have elastic force and surround the central portion.

[0020] In the power module according to the embodiment of the present invention, the movable members are symmetrical to the center of the locking portion.

[0021] In the power module according to the embodiment of the present invention, each second bending section has a plurality of holes.

[0022] In a power module according to an embodiment of the present invention, the power module includes a power component, wherein the power component is configured in a main shell and is pressed against a heat dissipation structure by at least one side wall. When the locking component passes through the locking portion and resists the elastic force of the movable part to lock the assembly component to the heat dissipation structure, the power component drives the main shell to be pressed against the heat dissipation structure through the elastic force of the movable part.

[0023] In the power module according to the embodiment of the present invention, when the locking member locks the assembly component to the heat dissipation structure, the side wall is close to the heat dissipation structure and there is a gap between the first bending section and the heat dissipation structure.

[0024] In the power module according to the embodiment of the present invention, the number of at least one assembly component is two, and the two assembly components are respectively located at two opposite sides of the main housing.

[0025] According to an embodiment of the present invention, a power module includes a main housing, a power component and at least one assembly component. The main housing has at least one side wall and at least two ribs extending from the side wall. The power component is arranged in the main housing and is pressed against the heat dissipation structure by the side wall. The assembly component includes a main section and two bending sections. The main section is located between the two ribs and includes a central portion, at least one movable part and a peripheral portion. The central portion has a locking portion, the peripheral portion surrounds the central portion, and the movable part is connected between the central portion and the peripheral portion. The two bending sections are respectively connected to the opposite side edges of the peripheral portion and are respectively embedded in the two ribs.

[0026] According to an embodiment of the present invention, a power module includes a main housing, a power component and at least one assembly component. The main housing has at least one side wall. The power component is arranged in the main housing and is pressed against the heat dissipation structure by the side wall. The assembly component includes a main section, two first bending sections and two second bending sections. The main section includes a central portion, at least one movable part and a peripheral portion. The central portion has a locking portion, the peripheral portion surrounds the central portion, and the movable part is connected between the central portion and the peripheral portion. The two first bending sections are respectively connected to the opposite side edges of the peripheral portion, and the two second bending sections are respectively connected to the two first bending sections and are buried in the side wall.

[0027] Based on the above, the present invention arranges the locking portion of the assembly component between the two convex ribs of the main shell or between the two first bending sections of the assembly component. Therefore, when the user passes the locking accessory through the locking portion for locking, the two convex ribs of the main shell or the two first bending sections of the assembly component can guide the locking accessory to avoid the locking accessory from being skewed. In addition, the present invention forms the movable part of the assembly component between the central part having the locking portion and the peripheral part surrounding the central part, rather than directly connecting the movable part to the main shell, so when the movable part is deformed in an unexpected manner due to the deflection of the locking accessory, the main shell can be prevented from being skewed or the degree of the main shell being skewed can be reduced. By observing that the top surface of the locking accessory is parallel to the peripheral part, the user can confirm that the locking accessory is correctly locked without deflection. Therefore, it can be ensured that the power components in the main shell are actually in contact with the heat dissipation structure and have good heat dissipation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a three-dimensional diagram of a power module according to an embodiment of the present invention;

[0029] Figure 2 yes Figure 1 A top view of a power module;

[0030] Figure 3 yes Figure 1 A side view of a power component mounted on a heat dissipation structure;

[0031] Figure 4 is a three-dimensional diagram of a power module according to another embodiment of the present invention;

[0032] Figure 5 yes Figure 4 A top view of a power module;

[0033] Figure 6 yes Figure 4 A side view of a power component mounted on a heat dissipation structure;

[0034] Figure 7 FIG. 4 is a top view of a power module according to another embodiment of the present invention. DETAILED DESCRIPTION

[0035] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0036] Figure 1 FIG. 4 is a perspective view of a power module according to an embodiment of the present invention. Figure 2 yes Figure 1 Please refer to the top view of the power module. Figure 1 and Figure 2The power module 100 of this embodiment includes a main housing 110, a power component 120, and at least one assembly component 130 (two are shown). The main housing 110 has at least one side wall 112 (multiple are shown) and at least two ribs 114 (four are shown) extending from the side wall 112. Two ribs 114 are located on one side of the main housing 110, and the other two ribs 114 are located on the other side of the main housing 110. The power component 120 (shown at Figure 2 ) is disposed in the main housing 110 and is surrounded by the side walls 112 and is tightly against the heat dissipation structure 60. The power component 120 may include a power chip and a substrate carrying the power chip. The two assembly components 130 are respectively located on opposite sides of the main housing 110 and correspond to the two ribs 114 and the other two ribs 114.

[0037] In detail, each assembly component 130 includes a main section 132 and two bending sections 134 (shown in FIG. Figure 1 and Figure 2 ). The main section 132 is located between the two convex ribs 114 and includes a central portion 132a, at least one movable member 132b (shown as a plurality) and a peripheral portion 132c. The movable member 132b may have elasticity. The central portion 132a has a locking portion 132a1 and is annular. The locking portion 132a1 is, for example, a locking hole. The peripheral portion 132c surrounds the central portion 132a. Each movable member 132b is connected between the central portion 132a and the peripheral portion 132c. The two bent sections 134 are respectively connected to the opposite sides of the peripheral portion 132c and are respectively embedded in the corresponding two convex ribs 114.

[0038] Figure 3 yes Figure 1 A side view of a power component mounted on a heat dissipation structure 60. Figure 3 As shown, when the locking member 50 passes through the locking portion 132a1 (indicated at Figure 2 ) and resists the elastic force of the movable part 132b to lock the assembly component 130 to the heat dissipation structure 60, the power component 120 drives the main shell 110 through the elastic force of the movable part 132b to be tightly against the heat dissipation structure 60, so that the heat generated by the power component 120 can be conducted to the heat dissipation structure 60.

[0039] As described above, in this embodiment, the locking portion 132a1 of the assembly component 130 is disposed between the two convex ribs 114 of the main housing 110. Therefore, when the user passes the locking member 50 through the locking portion 132a1 for locking, the two convex ribs 114 of the main housing 110 can guide the locking member 50 to prevent the locking member 50 from being skewed. In addition, as described above, in this embodiment, the movable member 132b of the assembly component 130 is formed between the central portion 132a having the locking portion 132a1 and the peripheral portion 132c surrounding the central portion 132a, rather than directly connecting the movable member 132b to the main housing 110. Therefore, when the movable member 132b is deformed in an unexpected manner due to the skewness of the locking member 50 and / or the uneven locking force of the two locking members 50, the main housing 110 can be prevented from being skewed or the degree of skewness of the main housing 110 can be reduced. Therefore, it can be ensured that the power component 120 in the main housing 110 is in reliable contact with the heat dissipation structure 60 to achieve good heat dissipation efficiency.

[0040] Furthermore, in each assembly component 130 of this embodiment, the movable parts 132b are as follows: Figure 2 As shown, the locking member 50 is symmetrical around the center of the central portion 132a and is symmetrical to the center of the locking portion 132a1. Therefore, if the locking member 50 locked to the assembly component 130 is not deflected, the top surface of the locking member 50 is parallel to the surrounding portion 132c, which is convenient for the user to observe. On the contrary, if the locking member 50 locked to the assembly component 130 is deflected, the top surface of the locking member 50 is deflected to the surrounding portion 132c. Therefore, as long as the user observes that the top surface of the locking member 50 is deflected to the surrounding portion 132c, it can be easily determined that the locking member 50 is deflected and needs to be re-locked.

[0041] Please refer to Figure 1 In the assembly component 130 of the present embodiment, each bending section 134 is perpendicular to the main section 132. As a result, the locking force of the locking member 50 is perpendicular to the extension direction of each bending section 134, so that each bending section 134 is less likely to be deformed unexpectedly due to the locking force. In addition, each bending section 134 of the present embodiment has a plurality of holes 134a, so that it can be firmly embedded in the corresponding rib 114 through these holes 134a. Moreover, by forming these holes 134a in each bending section 134, the weight of the assembly component 130 and the power module 100 including the same can be reduced, and the degree of thermal deformation of each bending section 134 can be reduced.

[0042] like Figure 1 As shown, the end 132c1 of the peripheral portion 132c of this embodiment is embedded in the side wall 112, so that the assembly component 130 is firmly combined with the main housing 110. On the other hand, the bottom end of the rib 114 of this embodiment is not aligned with the bottom end of the side wall 112. Figure 3When the assembly 130 is locked to the heat dissipation structure 60 by the locking member 50, there is a gap between the ribs 114 and the heat dissipation structure 60. Thus, the ribs 114 are prevented from contacting the heat dissipation structure 60, so that the bottom of the side wall 112 and the bottom surface of the power component 120 cannot be firmly supported against the heat dissipation structure 60.

[0043] Figure 4 is a three-dimensional diagram of a power module according to another embodiment of the present invention. Figure 5 yes Figure 4 Please refer to the top view of the power module. Figure 4 and Figure 5 The power module 200 of this embodiment includes a main housing 210, a power component 220, and at least one assembly component 230 (two are shown). The main housing 210 has at least one side wall 212 (multiple are shown). The power component 220 (shown at Figure 5 ) is disposed in the main housing 210 and is surrounded by the side walls 212 and is closely attached to the heat dissipation structure 60. The power component 220 may include a power chip and a substrate carrying the power chip. The two assembly components 230 are respectively located on opposite sides of the main housing 210.

[0044] In detail, each assembly component 230 includes a main section 232, two first bending sections 234 and two second bending sections 236 (shown in FIG. Figure 4 ). The main section 232 includes a central portion 232a, at least one movable member 232b (shown as a plurality) and a peripheral portion 232c. The central portion 232a has a locking portion 232a1 and is annular, the peripheral portion 232c surrounds the central portion 232a, and each movable member 232b is connected between the central portion 232a and the peripheral portion 232c. The two first bending sections 234 are respectively connected to the opposite sides of the peripheral portion 232c, and the two second bending sections 236 are respectively connected to the two first bending sections 234 and embedded in the side wall 212.

[0045] Figure 6 yes Figure 4 A side view of a power component mounted on a heat dissipation structure 60. Figure 6 As shown, when the locking member 50 passes through the locking portion 232a1 (indicated at Figure 4 and Figure 5 ) and resists the elastic force of the movable part 232b to lock the assembly component 230 to the heat dissipation structure 60, the power component 220 drives the main shell 210 through the elastic force of the movable part 232b and presses against the heat dissipation structure 60, so that the heat generated by the power component 220 can be conducted to the heat dissipation structure 60.

[0046] As described above, in this embodiment, the locking portion 232a1 of the assembly component 230 is disposed between the two first bent sections 234 of the assembly component 230. Therefore, when the user passes the locking member 50 through the locking portion 232a1 for locking, the two first bent sections 234 of the assembly component 230 can guide the locking member 50 to prevent the locking member 50 from being skewed. In addition, as described above, in this embodiment, the movable member 232b of the assembly component 230 is formed between the central portion 232a having the locking portion 232a1 and the peripheral portion 232c surrounding the central portion 232a, rather than directly connecting the movable member 232b to the main housing 210. Therefore, when the movable member 232b is deformed in an unexpected manner due to the skewness of the locking member 50 and / or the uneven locking force of the two locking members 50, the main housing 210 can be prevented from being skewed or the degree of skewness of the main housing 210 can be reduced. Therefore, it can be ensured that the power component 220 in the main housing 210 is in reliable contact with the heat dissipation structure 60 to achieve good heat dissipation efficiency.

[0047] Furthermore, in each assembly component 230 of this embodiment, the movable parts 232b are as follows: Figure 5 As shown, the locking member 50 is symmetrical around the center of the central portion 232a and is symmetrical to the center of the locking portion 232a1. Therefore, if the locking member 50 for locking the assembly 230 is not deflected, the top surface of the locking member 50 is parallel to the surrounding portion 232c. On the contrary, if the locking member 50 for locking the assembly 230 is deflected, the top surface of the locking member 50 is deflected to the surrounding portion 232c. Therefore, as long as the user observes that the top surface of the locking member 50 is deflected to the surrounding portion 232c, it can be easily determined that the locking member 50 is deflected and needs to be re-locked.

[0048] Please refer to Figure 4 In the assembly component 230 of the present embodiment, each first bending section 234 is perpendicular to the main section 232, and each second bending section 236 is also perpendicular to the main section 232. As a result, the locking force of the locking member 50 is perpendicular to the extension direction of each first bending section 234 and perpendicular to the extension direction of each second bending section 236, so that each first bending section 234 and each second bending section 236 are less likely to be deformed unexpectedly due to the locking force. In addition, each second bending section 236 of the present embodiment has a plurality of holes 236a, so that it can be firmly embedded in the side wall 212 through these holes 236a. Moreover, by forming these holes 236a in each second bending section 236, the weight of the assembly component 230 and the power module 200 including it can be reduced, and the degree of thermal deformation of each second bending section 236 can be reduced.

[0049] like Figure 4 As shown, the bottom end of the assembly component 230 of this embodiment is not aligned with the bottom end of the side wall 212. Figure 6When the assembly component 230 is locked to the heat dissipation structure 60 by the locking member 50, there is a gap between the first bending section 234 and the heat dissipation structure 60. Thus, the first bending section 234 is prevented from contacting the heat dissipation structure 60, so that the bottom end of the side wall 112 and the bottom surface of the power component 120 cannot be firmly supported against the heat dissipation structure 60.

[0050] Figure 7 FIG. 1 is a top view of a power module according to another embodiment of the present invention. Figure 7 In the power module 300, the main housing 310, the side wall 312, the power component 320, the assembly component 330, the main section 332, the central portion 332a, the locking portion 332a1, the movable part 332b, the peripheral portion 332c, and the first bending section 334 are configured and function in a manner similar to that of Figure 5 The configuration and function of the main housing 210, side wall 212, power component 220, assembly component 230, main section 232, central portion 232a, locking portion 232a1, movable member 232b, peripheral portion 232c, and first bending section 234 are not described in detail here. The power module 300 is different from the power module 200 in that the central portion 332a and movable member 332b form a square structure instead of a square structure. Figure 5 The central portion 232a and the movable part 232b form a circular structure.

[0051] In summary, the present invention arranges the locking portion of the assembly component between the two convex ribs of the main shell or between the two first bending sections of the assembly component. Therefore, when the user passes the locking accessory through the locking portion for locking, the two convex ribs of the main shell or the two first bending sections of the assembly component can guide the locking accessory to avoid the locking accessory from being skewed. In addition, the present invention forms the movable part of the assembly component between the central part having the locking portion and the peripheral part surrounding the central part, rather than directly connecting the movable part to the main shell. Therefore, when the movable part is deformed in an unexpected manner due to the deflection of the locking accessory, the main shell can be prevented from being skewed or the degree of the main shell being skewed can be reduced. By observing that the top surface of the locking accessory 50 is parallel to the peripheral part 132c, the user can confirm that the locking accessory 50 is locked correctly without deflection. Therefore, it can be ensured that the power components in the main shell are actually in contact with the heat dissipation structure and have good heat dissipation efficiency.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A power module, characterized in that: include: A main housing having at least one side wall and at least two ribs extending from the at least one side wall; as well as At least one assembly component includes a main section and two bent sections, the main section is located between the two convex ribs and includes a central portion, a peripheral portion surrounding the central portion, and at least two movable parts located between the central portion and the peripheral portion, the central portion has a locking portion, the at least two movable parts extend from the edge of the central portion to the peripheral portion respectively, and one of the at least two movable parts is separated from the other, the two bent sections are respectively connected to the opposite side edges of the peripheral portion and are respectively embedded in the at least two convex ribs, wherein the movable part provides an elastic force to the locking portion.

2. The power module according to claim 1, characterized in that: Each of the bending sections is perpendicular to the main section.

3. The power module according to claim 1, characterized in that: The central portion is annular.

4. The power module according to claim 1, characterized in that: The at least two movable parts are elastic and surround the central part.

5. The power module according to claim 4, characterized in that: The plurality of movable parts are symmetrical to the center of the locking portion.

6. The power module according to claim 1, characterized in that: Each of the bending sections has a plurality of holes.

7. The power module according to claim 1, characterized in that: The end of the peripheral portion is embedded in the at least one side wall.

8. The power module according to claim 1, characterized in that: It includes a power component, wherein the power component is configured in the main shell and is pressed against the heat dissipation structure by at least one side wall. When the locking component passes through the locking portion and resists the elastic force of the at least two movable parts to lock the at least one assembly component to the heat dissipation structure, the power component drives the main shell to be pressed against the heat dissipation structure through the elastic force of the at least two movable parts.

9. The power module according to claim 8, characterized in that: When the locking member locks the at least one assembly component to the heat dissipation structure, the at least one side wall is close to the heat dissipation structure and there is a gap between the at least two convex ribs and the heat dissipation structure.

10. The power module according to claim 1, characterized in that: The number of the at least one assembly component is two, and the two assembly components are respectively located on two opposite sides of the main shell.

11. A power module, characterized in that: include: A main housing having at least one side wall; as well as At least one assembly component includes a main section, two first bending sections and two second bending sections, the main section is located between the two first bending sections and includes a central portion, a peripheral portion surrounding the central portion, and at least two movable parts located between the central portion and the peripheral portion, the central portion has a locking portion, the at least two movable parts extend from the edge of the central portion to the peripheral portion, and one of the at least two movable parts is separated from the other, the two first bending sections are respectively connected to the opposite side edges of the peripheral portion, the two second bending sections are respectively connected to the two first bending sections and are respectively embedded in the at least one side wall, wherein the movable part provides an elastic force to the locking portion.

12. The power module according to claim 11, characterized in that: Each of the first bending sections is perpendicular to the main section.

13. The power module according to claim 11, characterized in that: Each of the second bending sections is perpendicular to the main section.

14. The power module according to claim 11, characterized in that: The central portion is annular.

15. The power module according to claim 11, characterized in that: The at least two movable parts are elastic and surround the central part.

16. The power module according to claim 15, characterized in that: The plurality of movable parts are symmetrical to the center of the locking portion.

17. The power module according to claim 11, characterized in that: Each of the second bending sections has a plurality of holes.

18. The power module according to claim 11, characterized in that: It includes a power component, wherein the power component is configured in the main shell and is pressed against the heat dissipation structure by at least one side wall. When the locking component passes through the locking portion and resists the elastic force of the at least two movable parts to lock the at least one assembly component to the heat dissipation structure, the power component drives the main shell to be pressed against the heat dissipation structure through the elastic force of the at least two movable parts.

19. The power module according to claim 18, characterized in that: When the locking member locks the at least one assembly component to the heat dissipation structure, the at least one side wall is close to the heat dissipation structure and a gap is formed between the first bending section and the heat dissipation structure.

20. The power module according to claim 11, characterized in that: The number of the at least one assembly component is two, and the two assembly components are respectively located on two opposite sides of the main shell.

21. A power module, characterized in that: include: A main housing having at least one side wall and at least two ribs extending from the at least one side wall; A power component is disposed in the main housing and is pressed against the heat dissipation structure by the at least one side wall; as well as At least one assembly component includes a main section and two bent sections, wherein the main section is located between the two convex ribs and includes a central portion, a peripheral portion surrounding the central portion, and at least two movable parts located between the central portion and the peripheral portion, the central portion has a locking portion, the at least two movable parts extend from the edge of the central portion to the peripheral portion respectively, and one of the at least two movable parts is separated from the other, the two bent sections are respectively connected to the opposite side edges of the peripheral portion and are respectively embedded in the at least two convex ribs, wherein the movable part provides an elastic force to the locking portion.

22. A power module, characterized in that: include: A main housing having at least one side wall; A power component is disposed in the main housing and is pressed against the heat dissipation structure by the at least one side wall; as well as At least one assembly component includes a main section, two first bending sections and two second bending sections, wherein the main section is located between the two first bending sections and includes a central portion, a peripheral portion surrounding the central portion, and at least two movable parts located between the central portion and the peripheral portion, the central portion has a locking portion, the at least two movable parts extend from the edge of the central portion to the peripheral portion, and one of the at least two movable parts is separated from the other, the two first bending sections are respectively connected to the opposite side edges of the peripheral portion, the two second bending sections are respectively connected to the two first bending sections and are respectively embedded in the at least one side wall, wherein the movable part provides an elastic force to the locking portion.

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