Method of assembling an electronic module

Abstract

The present application relates to an assembling method of an electronic module, comprising the steps of: (a) providing a first circuit board comprising a first surface and a second surface opposite to each other; (b) providing a second circuit board comprising a third surface, a fourth surface and a connecting device, wherein the third surface and the fourth surface are opposite to each other, and one end of the connecting device is connected to the third surface; (c) providing a solder ball, and stacking the first circuit board, the second circuit board and the solder ball in sequence, wherein the third surface of the second circuit board faces the second surface of the first circuit board, the other end of the connecting device is placed on the second surface of the first circuit board, and the solder ball is placed on the fourth surface of the second circuit board; and (d) performing a reflow soldering process, so that the connecting device is fixedly connected between the second surface of the first circuit board and the third surface of the second circuit board, the solder ball is fixedly connected to the fourth surface of the second circuit board, and an electronic module is formed.

Description

Technical Field

[0001] This case relates to an assembly method for an electronic module, and more particularly to an assembly method for an electronic module that improves the assembly process of solder balls and two stacked circuit boards to reduce the number of times components and solder balls undergo reflow soldering, thereby improving the reliability of the solder joints of the electronic module. Background Technology

[0002] In recent years, with the miniaturization of electronic products, electronic modules, while improving efficiency, also need to further increase power density by reducing size. To significantly reduce the size and weight of power modules and increase their power density, the use of a two-board stack design has become commonplace in the current market. The soldering assembly technology for this two-board stack involves each board having two opposing solder surfaces for mounting electronic components via a reflow soldering process, or for securing the electronic module to the system board. The connection between the two boards requires bidirectional conductive connectors, followed by a reflow soldering process to assemble the electronic module.

[0003] On the other hand, when an electronic module is connected to a system board via solder balls, there is an additional need to place solder balls on the electronic module. Since the placement of solder balls is similar to that of electronic components, it must be completed through a reflow soldering process, and the solder balls must be placed on the outer solder surface of the electronic module, spatially relative to the system board. Therefore, in an electronic module with two stacked circuit boards, on the circuit board opposite the system board, a second reflow soldering process is required to place the solder balls, electronic components, and bidirectional connectors on two opposite solder surfaces. Subsequently, another reflow soldering process is needed to connect the two circuit boards using the bidirectional connectors. In other words, on the circuit board adjacent to the system board, one of the two opposite solder surfaces must undergo at least three reflow soldering processes to complete the assembly structure of the electronic module. In other words, in the existing electronic module assembly structure, the solder balls used to connect the system board or the bidirectional conductive connectors used to connect the two circuit boards need to undergo more than three reflow soldering processes to complete the assembly. This results in long manufacturing time and high cost, and also increases the risk of damage to the solder balls, bidirectional conductive connectors or other electronic components during the high-temperature reflow soldering process, reducing the reliability of the soldering between the electronic module and the system board.

[0004] Therefore, developing an assembly method for electronic modules, improving the assembly process of solder balls and two stacked circuit boards to reduce the number of times electronic components, connectors, and solder balls undergo reflow soldering, and improving the reliability of electronic module solder joints, is a crucial issue that needs to be addressed in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a method for assembling electronic modules. By assembling solder balls with two stacked circuit boards, the number of times electronic components, connectors, and solder balls on these two circuit boards undergo reflow soldering is reduced, simplifying the production process of electronic modules, saving investment in production equipment, saving space in the production workshop, and simultaneously helping to improve the production efficiency and reliability of the solder joints of electronic modules.

[0006] Another objective of this invention is to provide a method for assembling electronic modules. By combining two stacked circuit boards and solder balls in a single reflow soldering process, it ensures that the electronic components, connectors, and solder balls on the two stacked circuit boards undergo no more than two reflow soldering cycles. When the electronic module is then connected to a system board via solder balls through a reflow soldering process, it ensures that the electronic components, connectors, and solder balls undergo no more than three reflow soldering cycles, improving the reliability of the soldering between the electronic module and the system board and increasing the product's competitiveness. Furthermore, the two stacked circuit boards can be reinforced with adhesive to enhance the fixation, preventing misalignment or separation during stacking or reflow soldering. Moreover, the adhesive can be cured simultaneously during the high temperature of the reflow soldering process, further simplifying the manufacturing process and improving product reliability.

[0007] To achieve the aforementioned objective, this application provides a method for assembling an electronic module, comprising the steps of: (a) providing a first circuit board, including a first side and a second side opposite to each other; (b) providing a second circuit board, including a third side, a fourth side, and a connecting device, wherein the third side and the fourth side are opposite to each other, and one end of the connecting device is disposed on the third side through a first reflow soldering process; (c) providing solder balls, and sequentially stacking the first circuit board, the second circuit board, and the solder balls, wherein the third side of the second circuit board faces the second side of the first circuit board, the other end of the connecting device is placed on the second side of the first circuit board, and the solder balls are placed on the fourth side of the second circuit board; and (d) performing a second reflow soldering process, thereby fixing the connecting device between the second side of the first circuit board and the third side of the second circuit board, fixing the solder balls to the fourth side of the second circuit board, and forming an electronic module.

[0008] To achieve the aforementioned objective, this application provides a method for assembling an electronic module, comprising the steps of: (a) providing a first circuit board, including a first side and a second side opposite to each other; (b) providing a second circuit board, including a third side, a fourth side, and a connecting device, wherein the third side and the fourth side are opposite to each other, and one end of the connecting device is connected to the third side; (c) providing solder balls, and sequentially stacking the first circuit board, the second circuit board, and the solder balls, wherein the third side of the second circuit board faces the second side of the first circuit board, the other end of the connecting device is placed on the second side of the first circuit board, and the solder balls are placed on the fourth side of the second circuit board; and (d) performing a reflow soldering process, thereby fixing the connecting device between the second side of the first circuit board and the third side of the second circuit board, fixing the solder balls to the fourth side of the second circuit board, and forming an electronic module. Attached Figure Description

[0009] Figure 1 A perspective view of the electronic module of the first preferred embodiment of this case is provided.

[0010] Figure 2A This is to show an exploded view of the electronic module in the first preferred embodiment of this case;

[0011] Figure 2B This is an exploded view of the electronic module of the first preferred embodiment of the present invention from another perspective;

[0012] Figure 3 This is a schematic diagram illustrating the connection of the electronic module to a system board in the first preferred embodiment of this invention;

[0013] Figure 4 A flowchart illustrating the assembly method of the electronic module in a preferred embodiment of this invention;

[0014] Figure 5A and Figure 5B To illustrate a first exemplary example of stacking a first circuit board, a second circuit board, and solder balls in the assembly method of the electronic module in this case;

[0015] Figure 6A and Figure 6B To illustrate a second exemplary example of stacking a first circuit board, a second circuit board, and solder balls in the assembly method of the electronic module in this case;

[0016] Figure 7 A perspective view of the electronic module of the second preferred embodiment of this invention;

[0017] Figure 8 A top view of the electronic module in the second preferred embodiment of this invention.

[0018] [Symbol Explanation]

[0019] 1, 1a: Electronic module

[0020] 10: First circuit board

[0021] 11: First Page

[0022] 110: Solder pad

[0023] 12: Second page

[0024] 120: solder pad

[0025] 13: First Electronic Components

[0026] 20: Second circuit board

[0027] 21: Third page

[0028] 210: Solder pad

[0029] 22: Fourth page

[0030] 220: solder pad

[0031] 23: Connecting devices

[0032] 24: Second electronic components

[0033] 25: Groove

[0034] 30: Tin Ball

[0035] 40: Adhesive materials

[0036] 9: System board

[0037] 90: Welding surface

[0038] S1~S4: Steps

[0039] X, Y, Z: Axes Detailed Implementation

[0040] Some typical embodiments embodying the features and advantages of this invention will be described in detail in the following description. It should be understood that this invention can have various variations in different forms, all of which do not depart from the scope of this invention, and the descriptions and drawings herein are essentially illustrative and not intended to limit this invention. For example, if the following disclosure describes a first feature disposed on or above a second feature, it indicates that it includes embodiments where the first and second features are in direct contact, and also includes embodiments where additional features can be disposed between the first and second features, so that the first and second features may not be in direct contact. Furthermore, different embodiments in this disclosure may use repeated reference numerals and / or markings. These repetitions are for simplification and clarity and are not intended to limit the relationships between the various embodiments and / or the described appearance structures. Moreover, to facilitate the description of the relationship between one component or feature and another (plural) component or feature in the drawings, spatially related terms such as "below," "below," "lower part," "above," "upper part," and similar terms may be used. In addition to the orientations illustrated in the accompanying drawings, spatially relevant terms are used to cover different orientations of the device in use or operation. The device may also be otherwise positioned (e.g., rotated 90 degrees or located in other orientations), and the descriptions of the spatially relevant terms used will be interpreted accordingly. Furthermore, when a component is referred to as "connected to" or "coupled to" another component, it may be directly connected to or coupled to the other component, or there may be intervening components. Although the numerical ranges and parameters of the broad scope of this disclosure are approximate, values ​​are stated as precisely as possible in specific examples. Additionally, it is understood that while terms such as "first," "second," and "third" may be used in the claims to describe different components, these components should not be limited by these terms, and the components described accordingly in the embodiments are represented by different component symbols. These terms are used to distinguish different components. For example, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component without departing from the scope of the embodiments. The term "and / or" as thus used includes any or all combinations of one or more of the related listed items.

[0041] Figure 1 A perspective view of the electronic module of the first preferred embodiment of this invention. Figure 2A and Figure 2B This is an exploded view of the electronic module in the first preferred embodiment of the present invention. Figure 3This is a schematic diagram illustrating the connection of an electronic module to a system board according to a first preferred embodiment of the present invention. In this embodiment, the electronic module 1 includes a first circuit board 10, a second circuit board 20, and solder balls 30, which are stacked sequentially. The first circuit board 10 includes a first surface 11 and a second surface 12, which are two opposite surfaces. In this embodiment, the first circuit board 10 also includes a first electronic component 13, which is pre-positioned on a pad 110 on the first surface 11, for example, by a reflow soldering process. In other embodiments, the first electronic component 13 is pre-positioned on the first surface 11 and / or the second surface 12, for example, by soldering or other means, and this invention is not limited thereto. In this embodiment, the second circuit board 20 includes a third surface 21 and a fourth surface 22, which are two opposite surfaces. In addition, the third surface 21 of the second circuit board 20 is spatially opposite to the second surface 12 of the first circuit board 10, and the third surface 21 of the second circuit board 20 is spatially adjacent to the second surface 12 of the first circuit board 10. In this embodiment, the second circuit board 20 includes a connector 23 and a second electronic component 24, both pre-set on the pad 210 of the third surface 21. The connector 23 and the second electronic component 24 are configured, for example, through a single reflow soldering process (first reflow soldering process). The connector 23 is selected from, for example, one of the groups consisting of copper pillars, copper blocks, pin headers, and copper foil, and is electrically connected between the first circuit board 10 and the second circuit board 20. In other embodiments, the configuration of the connector 23 and the second electronic component 24 can be adjusted according to actual application requirements, and this embodiment is not limited thereto. In this embodiment, solder balls 30 are spatially arranged on the fourth surface 22 of the second circuit board 20 relative to the fourth surface 22 of the second circuit board 20 to form a ball grid array (BGA) package for the electronic module 1 for surface mount packaging technology. The assembled electronic module 1 can then be surface-mount soldered onto a system board 9. For example, electronic module 1 can be rotated 180 degrees so that its fourth side 22 faces the soldering surface 90 of system board 9, so that the solder balls 30 of electronic module 1 contact the soldering surface of system board 9. Then, electronic module 1 can be installed onto system board 9 through a reflow soldering process.

[0042] It is worth noting that, in this embodiment, the first circuit board 10, the second circuit board 20, and the solder balls 30 are stacked using, for example, surface mount technology, and then assembled into electronic module 1 through a reflow soldering process. Since the solder balls 30 and the two stacked circuit boards undergo a single reflow soldering process, the number of reflow soldering processes experienced by the solder balls 30 when the electronic module 1 is then connected to the system board 9 does not exceed two. This effectively reduces the risk of damage to the solder balls 30 during the high-temperature reflow soldering process and improves the reliability of the soldering between the electronic module 1 and the system board 9. The assembly method of electronic module 1 is further detailed below.

[0043] Figure 4 A flowchart illustrating a preferred embodiment of the electronic module assembly method of this invention. (Reference) Figures 1 to 4 Assembling electronic module 1, firstly, as shown in step S1, a first circuit board 10 is provided, including a first side 11 and a second side 12 opposite to each other. The first circuit board 10 may have a first electronic component 13 disposed on the first side 11 and / or the second side 12, depending on the actual application requirements. In this embodiment, the first electronic component 13 is disposed on the first side 11, while the second side 12 of the first circuit board 10 is assembled for subsequent structural stacking. Additionally, as shown in step S2, a second circuit board 20 is provided, including a third side 21 and a fourth side 22 opposite to each other. In this embodiment, the second circuit board 20 further includes a connecting device 23 and a second electronic component 24 disposed on the third side 21. The second electronic component 24 and the connecting device 23 are offset from each other, and the height of the connecting device 23 is greater than or equal to the height of the second electronic component 24. In this embodiment, the placement of the connecting device 23 and the second electronic component 24 can be completed, for example, through a single reflow soldering process (first reflow soldering process). One end of the connecting device 23 is connected to the pad 210 on the third surface 21. In other embodiments, the connecting device 23 can be pre-positioned on the third surface 21 of the second circuit board 20 through other bonding methods, which will not be described in detail here. Then, as shown in step S3, the first circuit board 10, the second circuit board 20, and the solder balls 30 are stacked sequentially. In this embodiment, since the second electronic component 24 and the connecting device 23 are misaligned, and the height of the connecting device 23 is greater than or equal to the height of the second electronic component 24, when the third surface 21 of the second circuit board 20 is stacked facing the second surface 12 of the first circuit board 10, the other end of the connecting device 23 can be placed on the second surface 12 of the first circuit board 10 and abut against the pad 120. In addition, the solder balls 30 can also be placed on the fourth surface 22 of the second circuit board 20 through a surface mount technology. Finally, as shown in step S4, a reflow soldering process (second reflow soldering process) is performed on the structure completed by stacking the first circuit board 10, the second circuit 20, and the solder balls 30. This fixes the other end of the connector 23 to the second surface 12 of the first circuit board 10, and the connector 23 is fixedly connected between the second surface 12 of the first circuit board 10 and the third surface 21 of the second circuit board 20. The solder balls 30 are then fixedly connected to the fourth surface 22 of the second circuit board 20, thus completing the assembly of the electronic module 1. The solder balls 30 undergo only one reflow soldering process. If the electronic module 1 is then connected to the system board 9, the solder balls 30 will undergo two reflow soldering processes, effectively reducing the risk of damage to the solder balls 30 during the high-temperature reflow soldering process and improving the reliability of the soldering between the electronic module 1 and the system board 9.

[0044] In this embodiment, the first electronic component 13 is pre-installed on the first side 11 and / or the second side 12 of the first circuit board 10, for example, through a reflow soldering process (first reflow soldering process). Furthermore, in the reflow soldering process performed after stacking the first circuit board 10, the second circuit 20, and the solder balls 30 (second reflow soldering process), the first electronic component 13 undergoes another high-temperature reflow soldering process. Therefore, the first electronic component 13 undergoes two reflow soldering processes during the production process. If the electronic module 1 is then connected to the system board 9, the first electronic component 13 will not undergo more than three reflow soldering processes, reducing the risk of the first electronic component 13 detaching or shifting during the high-temperature reflow soldering process and improving the production reliability of the electronic module.

[0045] In this embodiment, the connector 23 and the second electronic component 24 are pre-positioned on the third side 21 of the second circuit board 20, for example, through a reflow soldering process (first reflow soldering process). Furthermore, in the reflow soldering process (second reflow soldering process) performed after stacking the first circuit board 10, the second circuit 20, and the solder balls 30, the connector 23 and the second electronic component 24 undergo another high-temperature reflow soldering process. Therefore, the connector 23 and the second electronic component 24 undergo two reflow soldering processes during the production process. If the electronic module 1 is then connected to the system board 9, the connector 23 and the second electronic component 24 will not undergo more than three reflow soldering processes, reducing the risk of the connector 23 and the second electronic component 24 detaching or shifting during the high-temperature reflow soldering process and improving the production reliability of the electronic module.

[0046] As can be seen from the above, this invention reduces the number of times the first electronic component 13, the second electronic component 24, the connector 23, and the solder ball 30 undergo reflow soldering by assembling the first circuit board 10, the second circuit 20, and the solder ball 30. This simplifies the production process of the electronic module 1, saves investment in production equipment, saves space for equipment placement in the production workshop, and helps to improve the production efficiency of the electronic module 1 and the reliability of the solder joints of the electronic module 1.

[0047] Additionally, it should be noted that, in this embodiment, the stacking process of the first circuit board 10, the second circuit 20, and the solder balls 30 before the reflow soldering process (second reflow soldering process) can be adjusted according to actual application requirements. Figure 5A and Figure 5B To illustrate a first exemplary example of stacking a first circuit board, a second circuit board, and solder balls in the assembly method of the electronic module in this case, in this embodiment, solder is first pre-applied to the pads 120 on the second side 12 of the first circuit board 10. Additionally, in... Figure 5AAs shown, with the third surface 21 of the second circuit board 20 facing the second surface 12 of the first circuit board 10, the second circuit board 20 is placed on the second surface 12 of the first circuit board 10 using, for example, a surface mount technology, such that the other end of the connector 23 abuts against the pad 120 on the second surface 12. Then, as... Figure 5B As shown, solder is pre-applied to the pads 220 on the fourth side 22 of the second circuit board 20, and solder balls 30 are placed on the fourth side 22 of the second circuit board 20 using, for example, a surface mount technology. At this time, the structure completed by stacking the first circuit board 10, the second circuit 20, and the solder balls 30 is as described above. The connector 23 is not fully soldered to the pads 120 on the pre-applied second side 12, and the solder balls 30 are not fully soldered to the pads 220 on the pre-applied fourth side 22. After performing a reflow soldering process (second reflow soldering process), the connector 23 can be simultaneously fixed between the second side 12 of the first circuit board 10 and the third side 21 of the second circuit board 20, and the solder balls 30 can be fixedly connected to the fourth side 22 of the second circuit board 20. The assembled electronic module 1 is as follows. Figure 1 As shown.

[0048] Figure 6A and Figure 6B To illustrate a second exemplary example of stacking a first circuit board, a second circuit board, and solder balls in the assembly method of the electronic module in this case. In this embodiment, solder is pre-applied to pads 220 on the fourth side 22 of the second circuit board 20, and solder balls 30 are placed on the fourth side 22 of the second circuit board 20 using, for example, a surface mount technology. Figure 6A As shown. Next, solder is pre-applied to the pads 120 on the second side 12 of the first circuit board 10. As... Figure 6B As shown, with the third side 21 of the second circuit board 20 facing the second side 12 of the first circuit board 10, the second circuit board 20 containing solder balls 30 is placed on the second side 12 of the first circuit board 10 using, for example, a surface mount technology, so that the other end of the connector 23 abuts against the pad 120 on the second side 12. At this time, the structure completed by stacking the first circuit board 10, the second circuit 20, and the solder balls 30 is as described above. The connector 23 is not fully soldered to the pad 120 of the second side 12, which has been pre-soldered, and the solder balls 30 are not fully soldered to the pad 220 of the fourth side 22, which has been pre-soldered. After performing a reflow soldering process (second reflow soldering process), the connector 23 can be simultaneously fixed between the second side 12 of the first circuit board 10 and the third side 21 of the second circuit board 20, and the solder balls 30 can be fixedly connected to the fourth side 22 of the second circuit board 20. The assembled electronic module 1 is as follows. Figure 1 As shown.

[0049] It should be noted that the stacking process of the first circuit board 10, the second circuit 20, and the solder balls 30 before the reflow soldering process (second reflow soldering process) can be adjusted according to actual application requirements to increase the flexibility of the assembly process and accommodate different processes and equipment, as long as it does not affect the reduction of the number of times the first electronic component 13, the second electronic component 24, the connector 23, and the solder balls 30 undergo reflow soldering. This application is not limited to this.

[0050] Figure 7 A perspective view of the electronic module of the second preferred embodiment of this invention. Figure 8 A top view is provided to illustrate the electronic module of the second preferred embodiment of this invention. In this embodiment, electronic module 1a and... Figures 1 to 3 The power module 1 shown is similar, and the same component designations represent the same components, structures, and functions, which will not be described again here. In this embodiment, the power module 1a also includes an adhesive 40, disposed between the second surface 12 of the first circuit board 10 and the third surface 21 of the second circuit board 20, to enhance the fixing effect between the first circuit board 10 and the second circuit board 20. In one embodiment, the adhesive 40 is added together when the second circuit board 20 is stacked on top of the first circuit board 10 to enhance the fixing effect between the first circuit board 10 and the second circuit board 20, and to prevent misalignment or separation of the first circuit board 10 and the second circuit board 20 before the reflow soldering process (second reflow soldering process) is performed. In one embodiment, the adhesive 40 is, for example, a thermosetting epoxy resin. The adhesive 40, bonded to the first circuit board 10, the second circuit 20, and the solder balls 30, forms a stacked structure that cures during the reflow soldering process (second reflow soldering process), effectively preventing the electronic module 1a from bonding to the system board 9 (see [link]). Figure 3 During the reflow soldering process, a defect occurs where the first circuit board 10 and the second circuit board 20 are misaligned or separated.

[0051] In this embodiment, the second circuit board 20 includes a pair of grooves 25 recessed into two opposite side edges of the second circuit board 20. Adhesive material 40 is injected through these grooves 25 between the second surface 12 of the first circuit board 10 and the third surface 21 of the second circuit board 20 to enhance the fixation between the first circuit board 10 and the second circuit board 20. In this embodiment, the two adhesive materials 40 are, for example, adjacent to the two ends of a single groove 25 to form a stable fixation between the first circuit board 10 and the second circuit board 20, effectively preventing the electronic module 1a from detaching from the system board 9 (see [link]). Figure 3During the reflow soldering process, misalignment or separation of the first circuit board 10 and the second circuit board 20 may occur. Of course, the position and quantity of the adhesive material 40 and the grooves 25 can be adjusted according to actual application requirements. This case is not limited to this and will not be elaborated further.

[0052] In other embodiments, the pre-setting of the first electronic component 13, the second electronic component 24, and the connecting device 23 can be, for example, but not limited to, a reflow soldering process or other insertion methods. However, by pre-setting the first electronic component 13, the second electronic component 24, and the connecting device 23, and by stacking the first circuit board 10, the second circuit board 20, and the solder balls 30 together for reflow soldering, the number of reflow soldering operations performed on the delicate components in the electronic modules 1 and 1a can be controlled to within two times, based on the principle shown in this embodiment. When the electronic modules 1 and 1a are reflow soldered with the system board 9 (see...) via solder balls... Figure 3 When connecting the components, it can be ensured that the first electronic component 13, the second electronic component 24, the connector 23, and the solder ball 30 undergo no more than three reflow soldering processes, improving the reliability of the electronic module and system board soldering and increasing the product's competitiveness. Further details are omitted here.

[0053] In summary, this invention provides a method for assembling an electronic module. By assembling solder balls with two stacked circuit boards, the number of reflow soldering operations performed on the electronic components, connectors, and solder balls on the two stacked circuit boards is reduced, simplifying the electronic module manufacturing process, saving investment in production equipment, and conserving space in the production workshop. This also helps improve the production efficiency and solder joint reliability of the electronic module. Furthermore, by performing a single reflow soldering process on the two stacked circuit boards and solder balls together, the number of reflow soldering operations performed on the electronic components, connectors, and solder balls on the two stacked circuit boards is ensured to be no more than two. When the electronic module is then connected to the system board via a reflow soldering process using solder balls, the number of reflow soldering operations performed on the electronic components, connectors, and solder balls is ensured to be no more than three, improving the reliability of the soldering between the electronic module and the system board and increasing product competitiveness. On the other hand, the two stacked circuit boards can be reinforced with adhesive to prevent misalignment or separation during stacking or reflow soldering. Moreover, the adhesive can be cured simultaneously at the high temperature of the reflow soldering process, further simplifying the manufacturing process and improving product reliability.

[0054] This case may be modified in various ways by those skilled in the art, but all modifications shall not fall outside the scope of protection sought by the appended claims.

Claims

1. A method for assembling an electronic module, characterized in that, Including the following steps: (a) A first circuit board is provided, including a first side and a second side opposite to each other; (b) A second circuit board is provided, including a third side, a fourth side and a connecting device, wherein the third side and the fourth side are opposite to each other, and one end of the connecting device is disposed on the third side by a first reflow soldering process; (c) A solder ball is provided, and the first circuit board, the second circuit board and the solder ball are stacked sequentially to form a stacked structure, wherein the second side and the fourth side of the first circuit board face upward, the third side of the second circuit board faces the second side of the first circuit board, the other end of the connector is placed on the second side of the first circuit board and is not soldered to the second side, the solder ball is placed on the fourth side of the second circuit board and is not soldered to the fourth side, and the solder ball is located on the upper side of the stacked structure; as well as (d) A second reflow soldering process is performed on the stacked structure to fix the connector between the second side of the first circuit board and the third side of the second circuit board, and the solder ball is fixedly connected to the fourth side of the second circuit board to form the electronic module.

2. The assembly method of the electronic module according to claim 1, characterized in that, Step (a) includes the step of: (a1) placing a first electronic component on the first surface and / or the second surface through another reflow soldering process, wherein the first electronic component undergoes two reflow soldering processes during the assembly process.

3. The assembly method of the electronic module according to claim 1, characterized in that, Step (b) includes the step of: (b1) placing a second electronic component on the third surface through the first reflow soldering process, wherein the second electronic component and the connecting device are misaligned, and the height of the connecting device is greater than or equal to the height of the second electronic component, wherein the second electronic component undergoes two reflow soldering processes during the assembly process.

4. The assembly method of the electronic module according to claim 1, characterized in that, In step (c), the solder ball is placed on the fourth surface of the second circuit board using a surface mount technology.

5. The assembly method of the electronic module according to claim 1, characterized in that, Step (c) includes the following steps: (c11) With the third surface facing the second surface, the second circuit board is placed on the second surface of the first circuit board; and (c12) Place the solder ball on the fourth surface of the second circuit board.

6. The assembly method of the electronic module according to claim 1, characterized in that, Step (c) includes the following steps: (c21) Place the solder ball on the fourth surface of the second circuit board; and (c22) With the third surface facing the second surface, place the second circuit board on the second surface of the first circuit board.

7. The assembly method of the electronic module according to claim 1, characterized in that, The solder ball is used to surface-mount the electronic module onto a system board.

8. The assembly method of the electronic module according to claim 1, characterized in that, The solder ball undergoes one reflow soldering process during assembly.

9. The assembly method of the electronic module according to claim 1, characterized in that, It also includes step (d0) of providing an adhesive material disposed between the second side of the first circuit board and the third side of the second circuit board.

10. The assembly method of the electronic module according to claim 9, characterized in that, The second circuit board includes a pair of recesses recessed on two opposite side edges of the second circuit board, wherein the adhesive is injected through the pair of recesses between the second surface of the first circuit board and the third surface of the second circuit board.

11. The assembly method of the electronic module according to claim 9, characterized in that, The adhesive material is cured during the second reflow soldering process.

12. A method for assembling an electronic module, characterized in that, Including the following steps: (a) A first circuit board is provided, including a first side and a second side opposite to each other; (b) A second circuit board is provided, including a third side, a fourth side and a connecting device, wherein the third side and the fourth side are opposite to each other and one end of the connecting device is connected to the third side; (c) A solder ball is provided, and the first circuit board, the second circuit board and the solder ball are stacked sequentially to form a stacked structure, wherein the second side and the fourth side of the first circuit board face upward, the third side of the second circuit board faces the second side of the first circuit board, the other end of the connector is placed on the second side of the first circuit board and is not soldered to the second side, the solder ball is placed on the fourth side of the second circuit board and is not soldered to the fourth side, and the solder ball is located on the upper side of the stacked structure; as well as (d) A reflow soldering process is performed on the stacked structure to fix the connector between the second side of the first circuit board and the third side of the second circuit board, and the solder ball is fixedly connected to the fourth side of the second circuit board to form the electronic module.

13. The assembly method of the electronic module according to claim 12, characterized in that, The connector is pre-installed on the third surface via another reflow soldering process.

14. The assembly method of the electronic module according to claim 12, characterized in that, The solder ball is used to surface-mount the electronic module onto a system board.

15. The assembly method of the electronic module according to claim 12, characterized in that, The solder ball undergoes one reflow soldering process during assembly.

16. The assembly method of the electronic module according to claim 12, characterized in that, The first circuit board includes a first electronic component, which is disposed on the first surface and / or the second surface by another reflow soldering process, wherein the first electronic component undergoes two reflow soldering processes during the production process.

17. The assembly method of the electronic module according to claim 12, characterized in that, The second circuit board includes a second electronic component, which is disposed on the third surface by another reflow soldering process, and the second electronic component undergoes two reflow soldering processes during the assembly process.

18. The assembly method of the electronic module according to claim 12, characterized in that, In step (c), the solder ball is placed on the fourth surface of the second circuit board using a surface mount technology.

19. The assembly method of the electronic module according to claim 12, characterized in that, Step (c) includes the following steps: (c11) With the third surface facing the second surface, the second circuit board is placed on the second surface of the first circuit board; and (c12) Place the solder ball on the fourth surface of the second circuit board.

20. The assembly method of the electronic module according to claim 12, characterized in that, Step (c) includes the following steps: (c21) Place the solder ball on the fourth surface of the second circuit board; and (c22) With the third surface facing the second surface, place the second circuit board on the second surface of the first circuit board.

21. The assembly method of the electronic module according to claim 12, characterized in that, It also includes step (d0) of providing an adhesive material disposed between the second side of the first circuit board and the third side of the second circuit board.

22. The assembly method of the electronic module according to claim 21, characterized in that, The second circuit board includes a pair of recesses recessed on two opposite side edges of the second circuit board, wherein the adhesive is injected through the pair of recesses between the second surface of the first circuit board and the third surface of the second circuit board.

23. The assembly method of the electronic module according to claim 21, characterized in that, The adhesive material is cured during the reflow soldering process.

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