Printed circuit board stacking method and system

Abstract

This application discloses a printed circuit board stacking method and system. The method includes providing a lower substrate and printing a first solder paste on the lower substrate; placing surface mount components on the lower substrate; providing an adapter board and placing the adapter board on the lower substrate; reflow soldering the lower substrate with the surface mount components and the adapter board so that the surface mount components and the adapter board are connected to the lower substrate through the first solder paste and form a first assembly; providing an upper substrate and printing a first solder paste and a second solder paste on the upper substrate; placing the surface mount components on the upper substrate and placing the first assembly on the upper substrate; reflow soldering the upper substrate with the surface mount components and the first assembly so that the surface mount components are connected to the upper substrate through the first solder paste and the first assembly is connected to the upper substrate through the second solder paste and form a printed circuit board. This application simplifies the printed circuit board stacking assembly process, thereby reducing the use of machines.

Description

Technical Field

[0001] This application relates to the field of semiconductor assembly, and more particularly to a printed circuit board stacking method and system. Background Technology

[0002] Existing circuit board stacking and assembly processes, taking a three-layer circuit board as an example, require separate processes for solder paste printing and reflow soldering on the upper substrate and adapter board, respectively. Then, they are mounted onto the lower substrate and reflow soldered again. The entire assembly process requires multiple surface mount technology (SMT) lines, making the process relatively complex and requiring a large number of machines. Summary of the Invention

[0003] In view of this, it is necessary to provide a printed circuit board stacking method and system that can reduce the number of machines used in circuit board assembly and simplify the assembly process.

[0004] A first aspect of this application provides a method for stacking printed circuit boards, comprising the following steps: providing a lower substrate and printing a first solder paste on the lower substrate; placing surface mount components on the lower substrate; providing an adapter board and placing the adapter board on the lower substrate; reflow soldering the lower substrate on which the surface mount components and the adapter board are placed, such that the surface mount components and the adapter board are connected to the lower substrate through the first solder paste and form a first assembly; providing an upper substrate and printing the first solder paste and a second solder paste on the upper substrate; placing surface mount components on the upper substrate and placing the first assembly on the upper substrate; reflow soldering the upper substrate on which the surface mount components and the first assembly are placed, such that the surface mount components are connected to the upper substrate through the first solder paste and the first assembly is connected to the upper substrate through the second solder paste and form the printed circuit board; wherein the melting point of the first solder paste is higher than that of the second solder paste.

[0005] Optionally, the step of providing an upper substrate and printing the first solder paste and the second solder paste on the upper substrate specifically includes: providing an upper substrate having an upper first surface and an upper second surface, wherein the upper first surface and the upper second surface are two opposing surfaces; printing the first solder paste on the upper substrate; and printing the second solder paste on the upper first surface of the upper substrate.

[0006] Optionally, the step of printing the first solder paste on the upper substrate specifically includes: printing the first solder paste on the upper second surface of the upper substrate; and printing the first solder paste on the upper first surface of the upper substrate.

[0007] Optionally, the step of printing the first solder paste on the upper first surface of the upper substrate specifically includes: laying a first stencil on the upper first surface; and printing the first solder paste on the upper first surface; the step of printing the second solder paste on the upper first surface of the upper substrate specifically includes: laying a second stencil on the upper first surface, wherein the second stencil is a stepped stencil used to cover the first solder paste; and printing the second solder paste on the upper first surface.

[0008] Optionally, the second stencil has a printing section and a blocking section, the blocking section and the printing section forming a stepped shape, the blocking section being used to block the first solder paste that has already been printed when printing the second solder paste.

[0009] Optionally, the shielding portion has a support structure for supporting the upper substrate.

[0010] Optionally, the printed circuit board stacking method further includes: after solder paste is printed on the upper substrate or the lower substrate, detecting whether there are defects in the printing of the solder paste, wherein the solder paste includes the first solder paste and the second solder paste; after the surface mount component is placed on the upper substrate or the lower substrate, detecting the placement position of the surface mount component; after the adapter board is placed on the lower substrate, detecting the placement position of the adapter board; and after the first component is placed on the upper substrate, detecting the placement position of the first component.

[0011] A second aspect of this application provides a printed circuit board stacking system, the system comprising: a solder paste printer for printing solder paste, wherein the solder paste includes a first solder paste and a second solder paste; a pick-and-place machine for placing components; and a reflow soldering machine for performing reflow soldering; wherein the solder paste printer, the pick-and-place machine, and the reflow soldering machine are configured to cooperate with each other to perform the printed circuit board stacking method described in any of the preceding claims.

[0012] Optionally, the system further includes a solder paste printing inspection machine for detecting whether the solder paste has defects.

[0013] Optionally, the system further includes: a first optical appearance inspection machine for detecting the placement position of the patch element, the placement position of the adapter plate, and the placement position of the first component; and a second optical appearance inspection machine for detecting whether there are defects in the soldering of the patch element, the adapter plate, and the first component.

[0014] Compared with the prior art, this application has at least the following advantages:

[0015] By directly mounting the adapter board as a component onto the lower substrate and reflow soldering it to form an assembly, and then mounting the assembly as a component onto the upper substrate and reflow soldering it, the number of SMT lines required in the assembly process is reduced, thereby simplifying the assembly process and reducing the use of machines. Attached Figure Description

[0016] Figure 1 This is a flowchart of a printed circuit board stacking method according to one embodiment of this application.

[0017] Figure 2 (A)- Figure 2 (H) is Figure 1 The diagram shows the structure of the method shown.

[0018] Figure 3 To execute Figure 1 The flowchart of step S15 is shown.

[0019] Figure 4 (A)- Figure 4 (B) is a schematic diagram of the first steel mesh and the upper substrate in one embodiment of this application.

[0020] Figure 5 (A)- Figure 5 (B) is a schematic diagram of the second steel mesh and the upper substrate in one embodiment of this application.

[0021] Figure 6 (A)- Figure 6 (B) is another schematic diagram of the second steel mesh and the upper substrate in one embodiment of this application.

[0022] Figure 7 This is a flowchart of a printed circuit board stacking method provided in another embodiment of this application.

[0023] Figure 8 This is a schematic diagram of a printed circuit board stacking system according to one embodiment of this application.

[0024] The following detailed description, in conjunction with the accompanying drawings, further illustrates this application.

[0025] Explanation of main component symbols

[0026] Lower substrate 100

[0027] Lower first surface 110

[0028] Lower second surface 120

[0029] Adapter board 200

[0030] Adapter plate first surface 210

[0031] Adapter plate second surface 220

[0032] Upper substrate 300

[0033] Upper first surface 310

[0034] Upper second surface 320

[0035] First pad 330

[0036] Second pad 340

[0037] First solder paste 410

[0038] Second solder paste 420

[0039] 500 surface mount components

[0040] First component 600

[0041] Printed Circuit Board 700

[0042] First Steel Mesh 810

[0043] Second steel mesh 820

[0044] Printing Department 822

[0045] Shielding part 823

[0046] Support structure 8231

[0047] Printed Circuit Board Stacking System 900

[0048] Solder paste printer 910

[0049] Pick and place machine 920

[0050] Reflow soldering machine 930

[0051] Solder paste printing inspection machine 940

[0052] First Optical Appearance Inspection Machine 950

[0053] Second optical appearance inspection machine 960 Detailed Implementation

[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0055] Please see Figure 1 and Figure 2 This application provides a printed circuit board stacking method, including the following steps:

[0056] Step S11: Provide a lower substrate 100 and print a first solder paste 410 on the lower substrate 100.

[0057] Please see Figure 2 (A) The lower substrate 100 has a lower first surface 110 and a lower second surface 120. A first pad (not shown) and a second pad (not shown) are pre-formed on the lower first surface 110 of the lower substrate 100. The first pad is used to connect the surface mount device 500 (see Figure 120). Figure 2 (B)), the second pad is used to connect the adapter board 200 (see reference). Figure 2 (C)). The first solder paste 410 is printed on the first pad and the second pad on the lower first surface 110.

[0058] It is understood that in some other embodiments, the lower second surface 120 may also be pre-set with the first pad, and the first solder paste 410 is also printed on the first pad on the lower second surface 120.

[0059] It is understood that, in this embodiment, the second pad (i.e., the location where the adapter board 200 is connected) is not limited to being located on the lower first surface 110 or the lower second surface 120. For example, the second pad may be disposed on the lower second surface 120.

[0060] In this embodiment, the first solder paste 410 can be printed on the lower substrate 100 using a solder paste printer (not shown).

[0061] Step S12: Place the patch element 500 on the lower substrate 100.

[0062] Please see Figure 2 (B) The patch element 500 is placed on the first pad (not shown) on the surface of the lower substrate 100 (e.g., on the lower first surface 110 shown in the figure).

[0063] It is understood that in some other embodiments, the surface mount element 500 only needs to be placed on the first pad on the lower second surface 120. In other embodiments, the surface mount element 500 needs to be placed on both the first pad on the lower first surface 110 and the first pad on the lower second surface 120.

[0064] In this embodiment, the patch element 500 can be placed on the lower substrate 100 by a pick-and-place machine (not shown).

[0065] Step S13: Provide an adapter plate 200 and place the adapter plate 200 on the lower substrate 100.

[0066] Please see Figure 2 (C) The adapter board 200 has a first surface 210 and a second surface 220. The first surface 210 and the second surface 220 are each pre-determined with a second pad (not shown). The second pad on the first surface 210 corresponds to the second pad on the lower first surface 110.

[0067] When the adapter board 200 is placed on the corresponding position on the lower substrate 100, the second pad on the first surface 210 of the adapter board will directly contact the first solder paste 410 on the first surface 110 of the lower substrate, thereby connecting the adapter board 200 and the lower substrate 100 together through the first solder paste 410.

[0068] In this embodiment, the adapter plate 200 can be placed on the lower substrate 100 by a pick-and-place machine (not shown).

[0069] It is understood that the pick-and-place machine used in steps S12 and S13 can be the same pick-and-place machine or different pick-and-place machines. For example, in step S12, a pick-and-place machine specifically designed for mounting smaller components (such as some resistors, capacitors, inductors, etc.) can be used. In step S13, a pick-and-place machine specifically designed for mounting larger components (such as the adapter board 200 or integrated chips in this application) can be used.

[0070] Step S14: The lower substrate 100 on which the surface mount element 500 and the adapter plate 200 are placed is reflow soldered so that the surface mount element 500 and the adapter plate 200 are connected to the lower substrate 100 through the first solder paste 410 and form the first component 600.

[0071] Please continue reading. Figure 2 (C) At this time, the lower substrate 100 holds the surface mount element 500 and the adapter plate 200. By placing the lower substrate 100 into a reflow soldering machine (not shown) for high-temperature reflow soldering (at least reaching the melting point of the first solder paste 410), the first solder paste 410 (not shown) will be melted. After cooling, the lower substrate 100, the surface mount element 500, and the adapter plate 200 will eventually form a whole, which constitutes the first component 600.

[0072] In this embodiment, the reflow soldering described above can be performed using a reflow soldering machine (not shown). It is understood that the soldering temperature setting within the reflow soldering machine is based on the melting point of the first solder paste 410. In this embodiment, the melting point of the first solder paste 410 is, for example, 220°C, therefore the soldering temperature of the reflow soldering machine is set to at least 220°C.

[0073] Step S15: Provide an upper substrate 300 and print the first solder paste 410 and the second solder paste 420 on the upper substrate 300.

[0074] Please see Figure 3 In this embodiment, step S15 specifically includes the following steps:

[0075] Step S151: Provide an upper substrate 300. The upper substrate 300 has an upper first surface 310 and an upper second surface 320.

[0076] It is understood that a first pad (not shown) and a second pad (not shown) are also pre-determined on the upper first surface 310 of the upper substrate 300. A first pad is pre-determined on the upper second surface 320 of the upper substrate 300.

[0077] Step S152: Print the first solder paste 410 on the upper second surface 320 of the upper substrate 300.

[0078] Please see Figure 2 (D) The first solder paste 410 is printed on the first pad (not shown) on the upper second surface 320.

[0079] It is understood that when the patch element 500 (not shown) does not need to be mounted on the upper second surface 320 of the upper substrate 300, step S152 can be omitted, that is, step S153 can be executed directly after step 151.

[0080] Step S153: Print the first solder paste 410 on the upper first surface 310 of the upper substrate 300.

[0081] Please see Figure 2 (E) The first solder paste 410 is printed on the first pad (not shown) on the upper first surface 310.

[0082] Step S154: Print the second solder paste 420 on the upper first surface 310 of the upper substrate 300.

[0083] Please continue reading. Figure 2(E) The second solder paste 420 is printed on the second pad (not shown) on the upper first surface 310.

[0084] In this embodiment, steps S152-S154 can be performed using a solder paste printer (not shown).

[0085] In this embodiment, step S154 specifically includes the following steps: laying a second stencil 820 on the upper first surface 310; and printing the second solder paste 420 on the upper first surface 310.

[0086] It is understood that in other embodiments of this application, the method further includes a step of laying a stencil when printing solder paste (including the first solder paste 410, see step S153, and the second solder paste 420, see step S154). For examples, please refer to [the relevant documentation / reference]. Figure 3 Step S153 specifically includes the following steps:

[0087] A first steel mesh 810 is laid on the upper first surface 310.

[0088] The first solder paste 410 is printed on the upper first surface 310.

[0089] Please refer to Figure 4 (A), 4(B), 5(A) and 5(B), in some embodiments, the steel mesh includes a first steel mesh 810 and a second steel mesh 820.

[0090] like Figure 4 In (A) and 4(B), when printing the first solder paste 410, a first stencil 810 can be laid first. The openings on the first stencil 810 correspond to the positions of the first pads 330 on the upper first surface 310, while the positions on the first stencil 810 corresponding to the second pads 340 are closed. Thus, after the first solder paste 410 is placed on the first stencil 810, and then squeegee (not shown) is used to scrape the solder, the first solder paste 410 is printed above the first pads 330.

[0091] For another example, please refer to Figure 5 In (A) and 5(B), when printing the second solder paste 420, a second stencil 820 can be laid first. The openings on the second stencil 820 correspond to the positions of the second pads 340 on the upper first surface 310, while the positions on the second stencil 820 corresponding to the first pads 330 are closed. Thus, after the second solder paste 420 is placed on the second stencil 820, and then squeegee (not shown) is used to scrape the solder, the second solder paste 420 is printed above the second pads 340.

[0092] It is understood that since the first solder paste 410 is already printed on the upper first surface 310 when the second solder paste 420 is printed, the second stencil 820 is a stepped stencil. The second stencil 820 has a printing section 822 and a blocking section 823. The blocking section 823 and the printing section 822 form a stepped shape. The blocking section 823 is used to block the already printed first solder paste 410 when the second solder paste 420 is printed. The specific positions of the printing section 822 and the blocking section 823 are not limited here and can be adjusted according to the required position and size of the first solder paste 410 and the second solder paste 420.

[0093] It is understood that in some embodiments, the shielding portion 823 may also be provided with a support structure 8231. The support structure 8231 is used to abut against the upper first surface 310 and is located between adjacent first pads 330 (or first solder paste 410). By providing the support structure 8231, it is possible to prevent the shielding portion 823 from pressing down and contacting the already printed first solder paste 410 when the squeegee is scraping solder.

[0094] Similarly, please see Figure 6 (A) and Figure 6 (B) The second stencil 820 includes a printing section 822 and a blocking section 823. The blocking section 823 is used to block the already printed second solder paste 420 when printing the first solder paste 410. Similarly, in these embodiments, the blocking section 823 may also be provided with a support structure 8231, the principle of which is similar to that described above and will not be repeated.

[0095] It is understood that the order of steps S152-S154 is not limited here. For example, in some embodiments, steps S153 and S154 can be interchanged, i.e., the second solder paste 420 is printed first, followed by the first solder paste 410. In this case, the first stencil 810 only needs to align the opening positions with the positions of the second pads 340 on the upper first surface 310, while the positions on the first stencil 810 corresponding to the first pads 330 are closed. The structure of the second stencil 820 will also change accordingly.

[0096] For example, step S152 can also be located after steps S153 and S154, that is, after the first solder paste 410 and the second solder paste 420 are printed on the upper first surface 310, the first solder paste 410 is then printed on the upper second surface 320.

[0097] It is understood that the first solder paste 410 and the second solder paste 420 have different melting points. In this embodiment, the melting point of the first solder paste 410 is higher than that of the second solder paste 420. For example, the melting point of the first solder paste 410 is 220°C, and the melting point of the second solder paste 420 is 190°C.

[0098] Step S16: Place the patch element 500 on the upper substrate 300 and place the first component 600 on the upper substrate 300.

[0099] Please see Figure 2 (F) The patch element 500 is placed on the first pad (not shown) on the surface of the upper substrate 300 (e.g., on the upper first surface 310 shown in the figure).

[0100] It is understood that in some other embodiments, the surface mount element 500 only needs to be placed on the first pad on the upper second surface 320. In other embodiments, the surface mount element 500 needs to be placed on both the first pad on the upper first surface 310 and the first pad on the upper second surface 320.

[0101] Please see Figure 2 (G) The first component 600 is placed on the upper first surface 310 of the upper substrate 300. The first component 600 is connected to the upper substrate 300 by contacting the second pad (not shown) on the second surface 220 of the adapter plate with the second solder paste 420 on the upper first surface 310.

[0102] It is understood that the placement order of the patch element 500 and the first component 600 is not limited here. In some other embodiments, the first component 600 may be placed first, and then the patch element 500 may be placed.

[0103] In this embodiment, the machine that places the surface mount element 500 and the first component 600 is a surface mount machine (as shown in the figure). Similarly, the surface mount machine that places the surface mount element 500 and the surface mount machine that places the first component 600 can be the same machine or different surface mount machines.

[0104] Step S17: The upper substrate 300 on which the surface mount element 500 and the first component 600 are placed is reflow soldered, so that the surface mount element 500 is connected to the upper substrate 300 through the first solder paste 410, and the first component 600 is connected to the upper substrate 300 through the second solder paste 420, thereby forming the printed circuit board 700.

[0105] Please see Figure 2(G) and Figure 2 (H) The upper substrate 300, on which the first component 600 and the surface mount element 500 are placed, is placed in a reflow soldering machine (not shown) for high-temperature (at least reaching the melting point of the first solder paste 410) reflow soldering. The first solder paste 410 (see...) Figure 2 (E)) and the second solder paste 420 will be melted. After cooling, the upper substrate 300, the surface mount element 500 and the first component 600 will eventually form a whole, which constitutes the printed circuit board 700.

[0106] In this embodiment, reflow soldering can be performed using a reflow soldering machine (not shown), and the temperature setting of the reflow soldering machine used in step S17 is set based on the melting points of the first solder paste 410 and the second solder paste 420. Specifically, the melting points of the first solder paste 410 and the second solder paste 420 are compared to obtain a higher temperature, and then the soldering temperature of the reflow soldering machine is set to be higher than this higher temperature.

[0107] By sharing a reflow soldering machine (i.e. sharing a reflow soldering temperature) with the first solder paste 410 and the second solder paste 420, and setting the soldering temperature to a temperature that can melt the first solder paste 410 which has a higher melting point, the first solder paste 410 and the second solder paste 420 can be melted simultaneously, reducing the use of the reflow soldering machine.

[0108] It is understood that the first solder paste 410 and the second solder paste 420 have different melting points. When the printed circuit board 700 needs to be disassembled for maintenance, a hot air gun is simply used and its temperature is adjusted to the melting point of the second solder paste 420 to melt the second solder paste 420 between the first component 600 and the upper substrate 300, thereby achieving disassembly. This simplifies the maintenance process of the printed circuit board 700.

[0109] Please refer to the following: Figure 1 and Figure 7 It can be understood that after printing the first solder paste 410 on the lower substrate 100 and printing the first solder paste 410 or the second solder paste 420 on the upper substrate 300, the printed circuit board stacking method further includes the following steps:

[0110] Step S181: Detect whether there are any defects in the printing of the first solder paste 410 or the second solder paste 420.

[0111] For example, after step S11, it can be checked whether the printing of the first solder paste 410 meets certain requirements in terms of thickness and area. Similarly, after step S15, it can also be checked whether the printing of the first solder paste 410 and the second solder paste 420 meets the requirements.

[0112] It is understood that step S181 can be performed by a solder paste inspection (SPI) machine.

[0113] After placing the surface mount element 500, the adapter board 200, or the first component 600, the printed circuit board stacking method further includes the following steps:

[0114] Step S182: Detect whether the position of the component is offset. The component may be, for example, the patch element 500, the adapter plate 200, or the first component 600.

[0115] In this embodiment, the placement of the component can be detected using an Automated Optical Inspection (AOI) machine.

[0116] Specifically, after placing the patch element 500 on the lower substrate 100 or the upper substrate 300 (i.e., after steps S12 and S16), the placement position of the patch element 500 is detected. After placing the adapter plate 200 on the lower first surface 110 of the lower substrate 100 (i.e., after step S13), the placement position of the adapter plate 200 is detected. After placing the first component 600 on the upper first surface 310 of the upper substrate 300 (i.e., in step S16), the placement position of the first component 600 is detected.

[0117] After reflow soldering, the printed circuit board stacking method further includes the following steps:

[0118] Step S183: Check for defects in the soldering of the component. The component may be, for example, the patch element 500, the adapter plate 200, or the first assembly 600.

[0119] In this embodiment, the weld defects can be detected by an Automated Optical Inspection (AOI) machine.

[0120] Specifically, after reflow soldering the lower substrate 100 or the upper substrate 300 on which the patch element 500 is placed (i.e., after step S14 and step S17), the soldering of the patch element 500 is checked for defects. After reflow soldering the lower substrate 100 on which the adapter plate 200 is placed (i.e., after step S14), the soldering of the adapter plate 200 is checked for defects. After reflow soldering the upper substrate 300 on which the first component 600 is placed (i.e., after step S17), the soldering of the first component 600 is checked for defects.

[0121] This application reduces the number of SMT lines required for assembly by directly mounting the adapter board 200 as a component onto the lower substrate 100 and performing reflow soldering to form the first component 600, and then mounting the first component 600 as a component onto the upper substrate 300 and performing reflow soldering. This simplifies the assembly process and reduces the use of machines.

[0122] Please see Figure 8 This application also provides a printed circuit board stacking system 900, which is used to cooperate with each other to stack and form corresponding printed circuit boards. The printed circuit board stacking system 900 includes a solder paste printer 910, a pick and place machine 920, a reflow soldering machine 930, a solder paste printing inspection machine 940, a first optical appearance inspection machine 950, and a second optical appearance inspection machine 960.

[0123] The solder paste printer 910 is used to print solder paste, for example, to perform steps S11 and S15. The solder paste is, for example,... Figure 2 The first solder paste 410 and the second solder paste 420 shown in (E).

[0124] The pick-and-place machine 920 is used to place components, for example, to perform steps 12, S13, and S16. The components are, for example,... Figure 2 The patch element 500, the adapter plate 200, and the first component 600 shown in (C).

[0125] The reflow soldering machine 930 is used to perform reflow soldering, for example, to execute steps S14 and S17.

[0126] The solder paste printing inspection machine 940 is used to detect whether the solder paste has defects. For example, it performs step S181.

[0127] The first optical appearance inspection machine 950 is used to detect the placement position of the patch element, the placement position of the adapter plate and the placement position of the first component, for example, to perform step S182.

[0128] The second optical appearance inspection machine 960 can also be used to detect whether there are defects in the soldering of the patch element 500, the adapter plate 200, or the first component 600. For example, by performing step S183.

[0129] It is understood that in this embodiment, multiple units of the solder paste printer 910, pick-and-place machine 920, reflow soldering machine 930, solder paste printing inspection machine 940, first optical appearance inspection machine 950, and second optical appearance inspection machine 960 can be provided. Multiple production lines are set up according to the printed circuit board stacking method to improve production efficiency. For example, in one embodiment, the printed circuit board stacking system includes two assembly lines for sequentially processing the lower substrate 100 and the upper substrate 300. In each line, the following are sequentially provided: Figure 8 Several machines are shown. Two lines work together to perform the printed circuit board stacking method described.

[0130] Those skilled in the art should recognize that the above embodiments are only used to illustrate this application and are not intended to limit this application. As long as they are within the essential spirit and scope of this application, appropriate changes and variations made to the above embodiments should fall within the scope of protection claimed in this application.

Claims

1. A method for stacking printed circuit boards, characterized in that, Includes the following steps: A lower substrate is provided, and a first solder paste is printed on the lower substrate; Place the patch element on the lower substrate; An adapter board is provided, and the adapter board is placed on the lower substrate; The lower substrate on which the surface mount components and the adapter board are placed is reflow soldered so that the surface mount components and the adapter board are connected to the lower substrate through the first solder paste and form a first assembly. A top substrate is provided, and a first solder paste and a second solder paste are printed on the top substrate; Place the patch element on the upper substrate and place the first component on the upper substrate; The upper substrate on which the surface mount components and the first component are placed is reflow soldered so that the surface mount components are connected to the upper substrate through the first solder paste, and the first component is connected to the upper substrate through the second solder paste, thereby forming the printed circuit board. The melting point of the first solder paste is higher than that of the second solder paste.

2. The printed circuit board stacking method as described in claim 1, characterized in that, The step of providing an upper substrate and printing the first solder paste and the second solder paste on the upper substrate specifically includes: An upper substrate is provided, the upper substrate having an upper first surface and an upper second surface, the upper first surface and the upper second surface being two opposing surfaces; The first solder paste is printed on the upper substrate; and The second solder paste is printed on the upper first surface of the upper substrate.

3. The printed circuit board stacking method as described in claim 1, characterized in that, The step of printing the first solder paste on the upper substrate specifically includes: The first solder paste is printed on the upper second surface of the upper substrate; and The first solder paste is printed on the upper first surface of the upper substrate.

4. The printed circuit board stacking method as described in claim 3, characterized in that, The step of printing the first solder paste on the upper first surface of the upper substrate specifically includes: A first steel mesh is laid on the upper first surface; and the first solder paste is printed on the upper first surface. The step of printing the second solder paste on the upper first surface of the upper substrate specifically includes: A second steel mesh is laid on the upper first surface, wherein the second steel mesh is a stepped steel mesh used to cover the first solder paste; and the second solder paste is printed on the upper first surface.

5. The printed circuit board stacking method as described in claim 4, characterized in that, The second stencil has a printing section and a blocking section. The blocking section and the printing section form a stepped shape. The blocking section is used to block the first solder paste that has already been printed when printing the second solder paste.

6. The printed circuit board stacking method as described in claim 5, characterized in that, The shielding portion has a support structure for supporting the upper substrate.

7. The printed circuit board stacking method as described in claim 1, characterized in that, The printed circuit board stacking method further includes: after solder paste is printed on the upper substrate or the lower substrate, detecting whether there are defects in the printing of the solder paste, wherein the solder paste includes the first solder paste and the second solder paste; After placing the patch element on the upper substrate or the lower substrate, the placement position of the patch element is detected; and After placing the adapter plate on the lower substrate, the placement position of the adapter plate is detected; and After placing the first component on the upper substrate, the placement position of the first component is detected.

8. A printed circuit board stacking system, characterized in that, The system includes: A solder paste printer for printing solder paste, wherein the solder paste includes a first solder paste and a second solder paste; A pick-and-place machine is used to place components; and A reflow soldering machine is used for reflow soldering. The solder paste printer, the chip mounter, and the reflow soldering machine are used to cooperate with each other to perform the printed circuit board stacking method as described in any one of claims 1 to 7.

9. The system as described in claim 8, characterized in that, The system also includes a solder paste printing inspection machine for detecting whether the solder paste has defects.

10. The system as described in claim 8, characterized in that, The system also includes: A first optical appearance inspection machine is used to inspect the placement position of the patch element, the placement position of the adapter plate, and the placement position of the first assembly; and The second optical appearance inspection machine is used to detect whether there are defects in the welding of the patch element, the adapter plate and the first component.

Images