Manufacturing method of multilayer circuit board

Abstract

The invention relates to a manufacturing method of a multi-layer circuit board. The manufacturing method of the multi-layer circuit board comprises the steps that a first pressing plate and a first layer plate are manufactured respectively; a mounting groove is formed in the first surface of the first pressing plate; putting a copper particle group into the mounting groove, wherein a groove is formed in one side, facing the first surface, of the copper particle group; the first laminate is laminated to the first surface of the first laminated plate, so that the first laminate covers the mounting groove; a first through hole is formed in the first layer plate, and the first through hole penetrates through the groove. According to the manufacturing method of the multi-layer circuit board, the problem that when the hole site is formed in the copper particle embedding position of the multi-layer circuit board, the hole forming tool needs to penetrate into the copper particle group is avoided, so that material consumption of the copper particle group is avoided, and meanwhile the problem that the copper particle group is loosened or broken due to the fact that the hole forming tool generates external force impact on the copper particle group is solved.

Description

Technical Field

[0001] The present application relates to the technical field of circuit board processing, and in particular to a method for manufacturing a multilayer circuit board. Background Art

[0002] During the use of the circuit board, many electronic components will be loaded. The performance of the electronic components will decline and be damaged when the temperature is too high. The overheating failure of the electronic components will affect the stability and reliability of the entire system. Therefore, the heat dissipation problem has always been the focus of attention in the production of circuit boards.

[0003] In the related art, an effective solution to the heat dissipation problem of circuit boards is to bury copper particles in the circuit boards. When the circuit boards generate heat, the copper particles can quickly transfer the heat to other parts to ensure the normal operation of the circuit boards. However, in the conventional circuit board manufacturing process, after the copper particles are buried in the circuit boards, it is often necessary to drill holes at the locations where the copper particles are buried. Drilling holes will cause material consumption of the copper particles, resulting in material waste, and drilling holes will produce a large external force impact on the copper particles, which is easy to cause problems such as loosening and damage of the copper particles. Summary of the invention

[0004] Based on this, it is necessary to provide a method for manufacturing a multilayer circuit board to avoid the waste of copper material and the loosening of copper particles caused by drilling holes on copper particles.

[0005] A method for manufacturing a multilayer circuit board, comprising:

[0006] respectively manufacturing a first pressed board and a first layer board;

[0007] A mounting groove is provided on the first surface of the first pressing plate;

[0008] Putting a copper particle group into the installation groove, wherein a groove is formed on a side of the copper particle group facing the first surface;

[0009] Laminating the first layer board onto the first surface of the first laminating board so that the first layer board covers the mounting groove;

[0010] A first through hole is opened on the first layer board so that the first through hole penetrates into the groove.

[0011] The technical solution is further described below:

[0012] In one embodiment, the copper grain group includes a first copper grain, a second copper grain and a third copper grain, wherein the step of placing the copper grain group into the installation groove and forming a groove on a side of the copper grain group facing the first surface specifically includes the following steps:

[0013] Putting the first copper particle, the second copper particle and the third copper particle into the installation groove;

[0014] The first copper particle, the second copper particle and the third copper particle are arranged in a direction parallel to the first surface, the second copper particle is located between the first copper particle and the third copper particle, and the height of the second copper particle is smaller than the height of the first copper particle and the height of the third copper particle, so that the groove is formed between the first copper particle and the third copper particle.

[0015] In one embodiment, after the step of opening a first through hole on the first layer board so that the first through hole penetrates the groove, the following steps are also included:

[0016] A communication metal layer is formed in the hole wall of the first through hole, so that the communication metal layer is connected to the copper particle group.

[0017] In one embodiment, after the step of forming a communication metal layer in the hole wall of the first through hole and connecting the communication metal layer to the copper particle group, the following steps are also included:

[0018] A back hole is opened in the first layer board, the back hole is connected to the end of the first through hole away from the copper particle group, the aperture of the back hole is larger than the aperture of the first through hole, and the depth of the back hole does not exceed the thickness of the first layer board.

[0019] In one embodiment, after the step of forming a back hole in the first layer, the method further includes the following steps:

[0020] Filling the back hole with resin;

[0021] The portion of the resin protruding from the surface of the first layer board is removed to make the surface of the resin flush with the surface of the first layer board.

[0022] In one embodiment, the step of laminating the first layer board onto the first surface of the first laminating board so that the first layer board covers the mounting groove specifically includes the following steps:

[0023] Disposing a first prepreg between the first pressing plate and the first layer plate;

[0024] The first pressing plate, the first prepreg sheet and the first layer plate are pressed together at a preset temperature and a preset pressure to form a multilayer plate.

[0025] In one embodiment, after the step of laminating the first laminating board, the first prepreg and the first layer board into one body at a preset temperature and a preset pressure to form a multilayer board, the following steps are further included:

[0026] removing burrs from the periphery of the multilayer board; and / or,

[0027] Grinding the surface of the multilayer board to roughen the surface of the multilayer board; and / or,

[0028] Excess copper material on the surface of the multilayer board is removed so that the thickness of the multilayer board reaches a preset thickness.

[0029] In one embodiment, after the step of laminating the first pressing plate, the first prepreg and the first layer plate into one body at a preset temperature and a preset pressure to form a multilayer plate, the method further comprises:

[0030] Electroplating a copper layer on the surface of the multilayer board; and / or,

[0031] A printing ink layer is formed on the surface of the multilayer board.

[0032] In one embodiment, the step of making the first pressed board specifically includes the following steps:

[0033] Make the second layer board and the third layer board respectively;

[0034] Disposing a second prepreg between the second layer and the third layer;

[0035] The second layer board, the second prepreg sheet and the third layer board are pressed together at a preset temperature and a preset pressure to form the first pressed board.

[0036] In one embodiment, the steps of making the first layer board, making the second layer board and making the third layer board all include the following steps:

[0037] Divide bulk materials into substrates of preset sizes;

[0038] Manufacturing circuit layers on both sides of the substrate;

[0039] The circuit layer is roughened.

[0040] In the above-mentioned method for manufacturing a multi-layer circuit board, before the copper particle group is buried in the installation groove of the first pressing plate, the copper particle group has already formed a groove, and then after the first layer of the board is pressed onto the first pressing plate, a first through hole is opened on the first layer of the board, and the first through hole is made to penetrate the groove, so that the first through hole is connected with the groove to form a required hole position. In this way, it is avoided that when opening a hole position at the buried copper particle position of the multi-layer circuit board, it is necessary to insert the hole-opening tool into the copper particle group, thereby avoiding the consumption of the copper particle group material, and also avoiding the problem of the copper particle group loosening or breaking due to the external force impact of the hole-opening tool on the copper particle group. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application.

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] In addition, the drawings are not drawn to a 1:1 scale, and the relative sizes of the various elements are drawn only as examples in the drawings and are not necessarily drawn according to the true scale.

[0044] Figure 1 The figure is a simplified structural diagram of a multilayer circuit board according to an embodiment.

[0045] Figure 2 Schematic diagram of the structure of a copper particle group according to an embodiment.

[0046] Figure 3 The figure is a schematic diagram of the structure of the first layer board, the second layer board and the third layer board of an embodiment.

[0047] Figure 4 The present invention is a flow chart of a method for manufacturing a multilayer circuit board according to an embodiment of the present invention.

[0048] Description of reference numerals:

[0049] 101, substrate; 102, circuit layer; 11, first laminate; 111, second layer; 112, third layer; 113, second prepreg; 12, first layer; 13, first prepreg; 14, first through hole; 15, back hole; 16, mounting groove; 20, copper particle group; 21, first copper particle; 22, second copper particle; 23, third copper particle; 24, groove. DETAILED DESCRIPTION

[0050] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0051] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0052] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0053] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0054] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0055] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0056] Specifically, in the conventional circuit board manufacturing process, copper particles are usually buried in the circuit board first, and then holes are drilled at the buried copper particles. When the holes penetrate the copper particles, the copper particles will be consumed, resulting in material waste. In addition, during the drilling process, the tool will exert a large external force impact on the copper particles, which can easily cause the buried copper particles to loosen and detach, or even cause the copper particles to break and damage.

[0057] Based on this, an embodiment of the present application provides a method for manufacturing a multilayer circuit board. Specifically, see Figure 1 as well as Figure 4 A method for manufacturing a multilayer circuit board according to an embodiment of the present invention comprises the following steps:

[0058] S110: manufacturing a first pressed plate 11 and a first layer plate 12 respectively;

[0059] Specifically, the first laminated board 11 may be formed by laminating a plurality of circuit boards, and the first layer board 12 may be a single circuit board or may be formed by laminating a plurality of circuit boards.

[0060] S120: opening a mounting groove 16 on the first surface of the first pressing plate 11;

[0061] For example, in one embodiment, the installation groove 16 can be formed by forming a groove on the first pressing plate 11. In other embodiments, the installation groove 16 can also be formed in other ways. Further, the size and shape of the installation groove 16 are consistent with the size and shape of the copper particle group 20 to be installed.

[0062] S130: placing the copper particle group 20 into the installation groove 16, wherein a groove 24 is formed on a side of the copper particle group 20 facing the first surface;

[0063] S140: Pressing the first layer board 12 onto the first surface of the first pressing board 11 so that the first layer board 12 covers the mounting groove 16;

[0064] S150: Opening a first through hole 14 on the first layer board 12 so that the first through hole 14 penetrates into the groove 24 .

[0065] In the above-mentioned method for manufacturing a multi-layer circuit board, before the copper particle group 20 is buried in the mounting groove 16 of the first pressing plate 11, the copper particle group 20 has already formed a groove 24, and then after the first layer board 12 is pressed onto the first pressing plate 11, a first through hole 14 is opened on the first layer board 12, and the first through hole 14 is made to penetrate the groove 24, so that the first through hole 14 is connected with the groove 24 to form a required hole position. In this way, it is avoided that when opening a hole position at the buried copper particle position of the multi-layer circuit board, it is necessary to insert the hole-opening tool into the copper particle group 20, thereby avoiding the consumption of the copper particle group 20 material, and also avoiding the problem that the hole-opening tool generates an external force impact on the copper particle group 20, causing the copper particle group 20 to loosen or break.

[0066] Alternatively, see Figure 2 In one embodiment, the copper particle group 20 includes three copper particles, namely, a first copper particle 21, a second copper particle 22, and a third copper particle 23. Therefore, the above step S130: placing the copper particle group 20 into the installation groove 16, and forming a groove 24 on the side of the copper particle group 20 facing the first surface specifically includes the following steps:

[0067] S131: placing the first copper grain 21, the second copper grain 22 and the third copper grain 23 into the mounting groove 16.

[0068] Among them, the first copper particle 21, the second copper particle 22 and the third copper are arranged in a direction parallel to the first surface, the second copper particle 22 is located between the first copper particle 21 and the third copper particle 23, and the height of the second copper particle 22 is smaller than the height of the first copper particle 21 and the height of the third copper particle 23, so that a groove 24 is formed between the first copper particle 21 and the third copper particle 23.

[0069] Exemplarily, in one embodiment, the height of the first copper particle 21 and the height of the third copper particle 23 are equal, and the height of the first copper particle 21 and the height of the third copper particle 23 are both flush with the first surface of the first pressing plate 11, thereby ensuring that the first pressing plate 11 and the first layer 12 can be tightly pressed. It is worth noting that the number of copper particles in the copper particle group 20 is not limited to three, and can also be two, three, four, five or more, as long as there is a height difference between the copper particles, and the height difference forms a groove 24. Furthermore, the number of grooves 24 formed on the copper particle group 20 is not limited to one. In other embodiments, the number of grooves 24 can also be two, three, four, etc., which can be set according to the hole positions that need to be opened on the multi-layer circuit board.

[0070] Specifically, a plurality of copper particles (such as the first copper particle 21, the second copper particle 22 and the third copper particle 23 of the present embodiment) are spliced ​​to form a copper particle group 20 having a groove 24, thereby avoiding the need to directly groove the copper particles with a tool, thereby avoiding damage to the copper particles, avoiding waste of copper materials, and reducing costs.

[0071] Step S150: after the step of opening the first through hole 14 on the first layer board 12 and making the first through hole 14 penetrate to the groove 24, the following steps are also included:

[0072] S161: a communication metal layer (not shown) is fabricated in the hole wall of the first through hole 14 , so that the communication metal layer is connected to the copper particle group 20 .

[0073] Exemplarily, the communication metal layer may be a copper layer. Specifically, after the first through hole 14 is formed on the first layer board 12, a copper layer may be deposited in the first through hole 14, so that a copper communication metal layer is formed in the hole wall of the first through hole 14. The communication metal layer enables each circuit layer 102 in the first laminate 11 to maintain communication connection with each circuit layer 102 of the first layer board 12.

[0074] After step S161: making a communication metal layer in the hole wall of the first through hole 14 and connecting the communication metal layer to the copper particle group 20, the following steps are also included:

[0075] S162: A back hole 15 is opened in the first layer board 12, and the back hole 15 is connected to the end of the first through hole 14 away from the copper particle group 20. The aperture of the back hole 15 is larger than the aperture of the first through hole 14, and the depth of the back hole 15 does not exceed the thickness of the first layer board 12.

[0076] Specifically, the diameter of the drill bit can be increased on the basis of the first through hole 14, so as to drill a back hole 15 at one end of the first through hole 14 away from the copper particle group 20, so as to remove part of the communication metal layer in the first through hole 14 to ensure signal integrity. Furthermore, the depth of the back hole 15 can be set according to the corresponding signal connection requirements, which is not limited here.

[0077] Optionally, in one embodiment, after step S162: the step of opening the back hole 15 in the first layer board 12, the following steps are also included:

[0078] S163: Filling the back hole 15 with resin (not shown);

[0079] Specifically, when filling the back hole 15 with resin, the resin needs to be filled to a level slightly higher than the back hole 15 to ensure that the resin fills the back hole 15. Filling the back hole 15 with resin can make the multilayer circuit board more robust and reliable, and improve its mechanical and electrical properties.

[0080] S164: removing the portion of the resin protruding from the surface of the first layer board 12 so that the surface of the resin is flush with the surface of the first layer board 12.

[0081] Specifically, the part of the resin protruding from the surface of the first layer 12 can be removed by grinding to ensure that the resin surface is flush with the surface of the first layer 12, so as to facilitate the subsequent surface treatment of the multi-layer circuit board. For example, after the step of grinding the resin, the steps of resin plugging hole inspection, LDI outer layer laser exposure, circuit plating, outer etching board, outer AOI and other processes can also be included, which will not be expanded here.

[0082] Optionally, in one embodiment, in step S140: the step of pressing the first layer board 12 onto the first surface of the first pressing board 11 so that the first layer board 12 covers the mounting groove 16 specifically includes the following steps:

[0083] S141: Arranging a first prepreg 13 between the first lamination plate 11 and the first layer plate 12;

[0084] Specifically, the semi-cured sheet is also called "PP sheet". The semi-cured sheet mainly consists of resin and reinforcing materials. The reinforcing materials are divided into several types such as glass fiber cloth, paper base, composite materials, etc. The semi-cured sheet can effectively bond multi-layer boards.

[0085] S142: Pressing the first pressing plate 11, the first prepreg 13 and the first layer board 12 together at a preset temperature and a preset pressure to form a multilayer board.

[0086] Specifically, at a preset temperature and a preset pressure, the first prepreg 13 melts to bond the first pressing plate 11 and the first layer 12. The first pressing plate 11, the first prepreg 13 and the first layer 12 are pressed into an integrated structure to form a multilayer board.

[0087] Optionally, in one embodiment, after step S142: pressing the first pressing plate 11, the first prepreg 13 and the first layer 12 together at a preset temperature and a preset pressure to form a multilayer plate, the following steps are further included:

[0088] S143: removing the burrs on the periphery of the multilayer board;

[0089] Specifically, the burrs on the periphery of the multilayer board can be removed by milling or grinding, so that the edges of the multilayer board are smooth and flat.

[0090] Optionally, in one embodiment, the following steps are also included:

[0091] S144: grinding the surface of the multilayer board to roughen the surface of the multilayer board;

[0092] Specifically, by grinding the surface of the multilayer board, the surface flash of the multilayer board can be removed, the surface of the multilayer board is roughened, and the contact area is increased, which is convenient for the subsequent attachment of the outer copper foil to the surface of the multilayer board.

[0093] Optionally, in one embodiment, the following steps are also included:

[0094] S145: removing excess copper material from the surface of the multilayer board so that the thickness of the multilayer board reaches a preset thickness.

[0095] Specifically, excess copper material on the surface of the multilayer board can be removed by chemical etching or the like, so that the thickness of the multilayer board reaches a preset thickness.

[0096] Optionally, after step S142: pressing the first pressing plate 11, the first prepreg 13 and the first layer 12 together at a preset temperature and a preset pressure to form a multilayer plate, the following steps are further included:

[0097] S171: electroplating a copper layer on the surface of a multilayer board;

[0098] Specifically, a layer of copper is plated on the multilayer board after copper deposition, which can thicken the copper surface and the circuit surface and improve the stability of the circuit board.

[0099] Optionally, in one embodiment, it further includes:

[0100] S172: Making a printing ink layer on the surface of the multilayer board.

[0101] Specifically, by printing a layer of ink on the multilayer board, it can play the role of insulation, anti-welding, and circuit protection. Further, after the ink layer is formed, the multilayer board can also be subjected to surface treatment, gong board, and electrical testing, etc., which will not be expanded here.

[0102] See also Figure 1 Optionally, in one embodiment, the first laminated board 11 includes a second layer board 111 and a third layer board 112. Step S110: the step of making the first laminated board 11 specifically includes the following steps:

[0103] S111: manufacturing the second layer board 111 and the third layer board 112 respectively;

[0104] S112: Disposing a second prepreg 113 between the second layer board 111 and the third layer board 112;

[0105] S113 : Pressing the second layer board 111 , the second prepreg 113 and the third layer board 112 together at a preset temperature and a preset pressure to form a first pressed board 11 .

[0106] Specifically, the method of pressing the second layer 111, the second prepreg 113 and the third layer 112 together can refer to the method of pressing the first laminate 11, the first prepreg 13 and the first layer 12 together to form a multilayer board in the above steps S141 to S142, which will not be described in detail here. Furthermore, after pressing the second layer 111, the second prepreg 113 and the third layer 112 together to form the first laminate 11, the first laminate 11 can also be subjected to peripheral burr removal, plate grinding, LDI inner layer laser exposure, inner layer etching, inner layer mid-inspection and inner layer browning, etc., which will not be expanded here.

[0107] See also Figure 3 Optionally, in one embodiment, the first layer board 12, the second layer board 111 and the third layer board 112 all include a substrate 101 and two circuit layers 102 formed on both sides of the substrate 101. Specifically, the steps of making the first layer board 12, the second layer board 111 and the third layer board 112 all include the following steps:

[0108] S101: dividing a bulk material into substrates 101 of a preset size;

[0109] Specifically, the bulk material may be a large-sized copper-clad laminate, and the substrate 101 may be obtained by cutting the large-sized copper-clad laminate into designed sizes.

[0110] S102: manufacturing circuit layers 102 on both sides of the substrate 101;

[0111] Specifically, the steps of making the circuit layer 102 on the substrate 101 are as follows: a photosensitive film is covered on the substrate 101, and ultraviolet rays are irradiated on the substrate 101 covered with the photosensitive film through the master sheet in a vacuum state to project the pattern on the master sheet onto the photosensitive film. Then, the photosensitive film on the light-blocking part (unexposed part) of the substrate 101 blocked by the master sheet is washed off with alkaline water, and the exposed copper is etched off with a chemical solution, so that the circuit layer 102 can be formed on the substrate 101. Finally, the substrate 101 is scanned by an optical instrument to check whether there are any defects.

[0112] S103: performing a roughening process on the circuit layer 102.

[0113] Exemplarily, the circuit layer 102 can be roughened by browning it. Specifically, the copper on the circuit layer 102 is oxidized to make the circuit layer 102 rough, which can enhance the bonding strength between the circuit layer 102 and the semi-cured sheet during lamination and avoid delamination or board explosion.

[0114] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0115] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A method for manufacturing a multilayer circuit board, characterized in that: include: respectively manufacturing a first pressed board and a first layer board; A mounting groove is provided on the first surface of the first pressing plate; Putting a copper particle group into the installation groove, wherein a groove is formed on a side of the copper particle group facing the first surface; Laminating the first layer board onto the first surface of the first laminating board so that the first layer board covers the mounting groove; A first through hole is opened on the first layer board so that the first through hole penetrates into the groove.

2. The method for manufacturing a multilayer circuit board according to claim 1, characterized in that: The copper particle group includes a first copper particle, a second copper particle and a third copper particle, wherein in the step of placing the copper particle group into the installation groove, a groove is formed on one side of the copper particle group facing the first surface. The following steps are involved: Putting the first copper particle, the second copper particle and the third copper particle into the installation groove; The first copper particle, the second copper particle and the third copper particle are arranged in a direction parallel to the first surface, the second copper particle is located between the first copper particle and the third copper particle, and the height of the second copper particle is smaller than the height of the first copper particle and the height of the third copper particle, so that the groove is formed between the first copper particle and the third copper particle.

3. The method for manufacturing a multilayer circuit board according to claim 1, characterized in that: After the step of opening a first through hole on the first layer board so that the first through hole penetrates the groove, the following steps are also included: A communication metal layer is formed in the hole wall of the first through hole, so that the communication metal layer is connected to the copper particle group.

4. The method for manufacturing a multilayer circuit board according to claim 3, characterized in that: After the step of forming a communication metal layer in the hole wall of the first through hole and connecting the communication metal layer to the copper particle group, the following steps are also included: A back hole is opened in the first layer board, the back hole is connected to the end of the first through hole away from the copper particle group, the aperture of the back hole is larger than the aperture of the first through hole, and the depth of the back hole does not exceed the thickness of the first layer board.

5. The method for manufacturing a multilayer circuit board according to claim 4, characterized in that: After the step of opening a back hole in the first layer, the following steps are also included: Filling the back hole with resin; The portion of the resin protruding from the surface of the first layer board is removed to make the surface of the resin flush with the surface of the first layer board.

6. The method for manufacturing a multilayer circuit board according to claim 4, characterized in that: The step of laminating the first layer board onto the first surface of the first laminating board so that the first layer board covers the mounting groove specifically includes the following steps: Disposing a first prepreg between the first pressing plate and the first layer plate; The first pressing plate, the first prepreg sheet and the first layer plate are pressed together at a preset temperature and a preset pressure to form a multilayer plate.

7. The method for manufacturing a multilayer circuit board according to claim 6, characterized in that: After the step of laminating the first pressing plate, the first prepreg and the first layer plate into one body at a preset temperature and a preset pressure to form a multilayer plate, the step further includes: removing burrs from the periphery of the multilayer board; and / or, Grinding the surface of the multilayer board to roughen the surface of the multilayer board; and / or, Excess copper material on the surface of the multilayer board is removed so that the thickness of the multilayer board reaches a preset thickness.

8. The method for manufacturing a multilayer circuit board according to claim 6, characterized in that: After the step of laminating the first pressing plate, the first prepreg and the first layer plate into one body at a preset temperature and a preset pressure to form a multilayer plate, the method further comprises: Electroplating a copper layer on the surface of the multilayer board; and / or, A printing ink layer is formed on the surface of the multilayer board.

9. The method for manufacturing a multilayer circuit board according to any one of claims 1 to 8, characterized in that: The step of making the first pressed plate specifically includes the following steps: Make the second layer board and the third layer board respectively; Disposing a second prepreg between the second layer and the third layer; The second layer board, the second prepreg sheet and the third layer board are pressed together at a preset temperature and a preset pressure to form the first pressed board.

10. The method for manufacturing a multilayer circuit board according to claim 9, characterized in that: The steps of making the first layer board, making the second layer board and making the third layer board all include the following steps: Divide bulk materials into substrates of preset sizes; Manufacturing circuit layers on both sides of the substrate; The circuit layer is roughened.

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