Circuit board

Abstract

The utility model belongs to the technical field of circuit board processing, and discloses a circuit board. The circuit board comprises two outer-layer boards and a plurality of core boards, all the core boards are clamped between the two outer-layer boards, prepregs are arranged between every two adjacent core boards in the two outer-layer boards and the plurality of core boards, hot melting modules are arranged on the top side and the bottom side of each core board, and in the two core boards close to the two outer-layer boards, the hot melting modules are arranged between the two core boards close to the two outer-layer boards. The hot melting modules, close to the sides of the outer layer plates, of the two core plates are first hot melting modules, each first hot melting module comprises a plurality of protrusions, the protrusions are arranged on the corresponding core plates at intervals, each protrusion extends in the thickness direction of the core plates, and the protrusions are used for transferring heat to the prepregs. The hot melting module on one side, close to the outer-layer plate, of the outermost-layer core plate cannot form a loop under the action of high-frequency electromagnetic wave current, local deformation of the outermost-layer core plate can be prevented, and blistering of the hot melting module can be avoided when high-temperature film pasting is carried out on the outer-layer plate during hot melting and after pressing.

Description

Technical Field

[0001] This utility model relates to the field of circuit board processing technology, and in particular to a circuit board. Background Technology

[0002] In the circuit board manufacturing process, a hot melt module is needed to melt the prepreg and then bond the core board and the outer layer together. In addition, in the circuit board manufacturing process, according to the changes in product structure, the impedance requirements are becoming more and more stringent, the outermost dielectric thickness is becoming thinner and thinner, and the prepreg used is also becoming thinner and thinner. Moreover, the prepreg used for the outermost layer is mostly a single sheet or flat cloth, and the adhesive content of the prepreg is relatively small.

[0003] Given the low adhesive content of the outermost prepreg, the hot-melt modules on the outermost core board are mostly made of copper. During hot-melt bonding, these modules form a circuit under the influence of high-frequency electromagnetic current, generating instantaneous heat. This localized high temperature at the hot-melt module location makes the outermost core board prone to localized deformation and unevenness, compromising its flatness. Furthermore, blistering at the hot-melt module location can lead to pressure loss and voids during lamination, ultimately causing the circuit board to fail when laminating core boards together or between the core board and the outer layer. Additionally, when applying a high-temperature film to the outer layer after lamination, the high temperature of the hot-melt module on the outermost core board also makes it prone to blistering, pressure loss, and voids. Utility Model Content

[0004] The purpose of this utility model is to provide a circuit board in which the hot melt module on the outermost core board near the outermost plate will not form a circuit under the action of high frequency electromagnetic wave current. This can prevent the hot melt module on the outermost core board from being at high temperature, causing local deformation of the outermost core board, and can avoid bubbling at the hot melt module position, as well as pressure loss and voids.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A circuit board includes two outer layers and multiple core boards, with all the core boards sandwiched between the two outer layers. A prepreg is provided between adjacent core boards. Each core board has a hot melt module on its top and bottom sides. In the two core boards closest to the two outer layers, the hot melt module on the side closest to the outer layers is a first hot melt module. The first hot melt module includes multiple protrusions spaced apart on the corresponding core boards. Each protrusion extends along the thickness direction of the core board. The protrusions transfer heat to the prepreg, and the gaps between the protrusions are used to fill the hot melt adhesive after the prepreg has melted.

[0007] In some possible implementations, the plurality of protrusions are arranged in a matrix on the corresponding core plate.

[0008] In some possible implementations, the protrusion is a cylindrical structure.

[0009] In some possible implementations, the first hot melt module further includes a first glue-filling area and a first glue-blocking line, all of the protrusions being located within the first glue-filling area, and the first glue-blocking line being disposed on one side of the first glue-filling area and away from the outer edge of the corresponding core board.

[0010] In some possible implementations, the hot melt modules on the top and bottom sides of the core plate away from the outer layer are both second hot melt modules. The second hot melt module includes at least one heat transfer plate disposed on the corresponding core plate. The heat transfer plate is used to transfer heat to the prepreg, and the gaps between the heat transfer plates are used to fill the hot melt adhesive after the prepreg has melted.

[0011] In some possible implementations, in the two core plates near the two outer layers, the hot melt module on the side of the two core plates away from the outer layers is the second hot melt module.

[0012] In some possible implementations, the heat transfer plate is a solid plate or a mesh plate.

[0013] In some possible implementations, when the heat transfer plate is a mesh plate, the second hot melt module further includes a second glue-filling area, which surrounds the mesh plate; the first hot melt module further includes a first glue-filling area, all of the protrusions are located within the first glue-filling area, and the coverage area of ​​the first glue-filling area on the corresponding core plate is smaller than the coverage area of ​​the second glue-filling area on the corresponding core plate.

[0014] In some possible implementations, when the heat transfer plate is a mesh plate, the second hot-melt module further includes a support member disposed on the corresponding core plate, the support member being located within the second glue-filling area and spaced apart from the mesh plate; and / or,

[0015] When the heat transfer plate is a mesh plate, the second hot melt module further includes a second adhesive blocking line, which is disposed on one side of the second adhesive filling area and away from the outer edge of the corresponding core plate.

[0016] In some possible implementations, the protrusion is made of copper.

[0017] The beneficial effects of this utility model are:

[0018] The circuit board provided by this utility model includes two outer layers and multiple core boards. Each core board has a hot-melt module on its top and bottom sides. In the two core boards closest to the two outer layers, the hot-melt module on the side of the core board closest to the outer layers is the first hot-melt module. The first hot-melt module includes multiple protrusions, which are spaced apart on the corresponding core boards. Each protrusion extends along the thickness direction of the core board and is used to transfer heat to the prepreg. During hot-melt, by spaced out the multiple protrusions, the hot-melt module on the side of the core board closest to the two outer layers is divided into independent small pieces. This prevents the hot-melt module from forming a circuit under the action of high-frequency electromagnetic wave current, thus preventing high temperature at the location of the hot-melt module and local deformation of the core board near the outer layers. During hot-melt and after pressing, when applying a high-temperature film to the outer layers, bubbling, pressure loss, and voids at the location of the hot-melt module can be avoided. Attached Figure Description

[0019] Figure 1 This is a structural schematic diagram of the core plate near the outer layer plate and the first hot melt module involved in this utility model;

[0020] Figure 2 This is a schematic diagram of the core plate and the second hot melt module that are far from the outer layer plate involved in this utility model.

[0021] Figure 3 This is an exploded view of a portion of the structure of the circuit board provided by this utility model.

[0022] In the picture:

[0023] 1. Core board; 10. Outer edge; 21. Protrusion; 22. First glue filling area; 23. First glue blocking line; 24. First board edge; 31. Heat transfer plate; 32. Second glue filling area; 33. Second glue blocking line; 34. Support member; 35. Second board edge. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0025] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0026] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0027] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0028] like Figures 1 to 3As shown, this utility model provides a circuit board including two outer layer boards and multiple core boards 1. All core boards 1 are sandwiched between the two outer layer boards. A prepreg is provided between adjacent core boards. Each core board 1 has a hot melt module on its top and bottom sides. In the two core boards 1 closest to the two outer layer boards, the hot melt module on the side closest to the outer layer board is a first hot melt module. The first hot melt module includes multiple protrusions 21, which are spaced apart on the corresponding core board 1. Each protrusion 21 extends along the thickness direction of the core board 1. The multiple protrusions 21 are used to transfer heat to the prepreg, and the gaps between the multiple protrusions 21 are used to fill the hot melt adhesive after the prepreg has melted. The core board 1 closest to the outermost core board is the outermost core board. During the heat fusion of the core board 1 and the outermost core board, multiple protrusions 21 are spaced apart to divide the heat-fused module on the side closest to the outermost core board 1 into independent small pieces. This prevents the heat-fused module on the side closest to the outermost core board 1 from forming a circuit under the influence of high-frequency electromagnetic current, thus preventing high temperatures and localized deformation at the heat-fused module location. During the heat fusion of the outermost core board and the core board 1, and during the high-temperature film application to the outermost core board after lamination, the multiple protrusions 21, when heated, prevent blistering, pressure loss, and voids at the heat-fused module location on the side closest to the outermost core board 1. Specifically, the outermost core board includes copper foil and solder resist film. The copper foil is positioned close to the core board 1, and the solder resist film is positioned on the side of the copper foil furthest from the core board 1.

[0029] Optionally, in this embodiment, multiple protrusions 21 are arranged in a matrix on the corresponding core plate 1. This arrangement facilitates processing, ensures uniform filling of the hot melt adhesive, and guarantees the flatness of adjacent core plates 1. Specifically, in this embodiment, the protrusions 21 are cylindrical structures, making their surfaces smooth, easy to fill with hot melt adhesive, and ensuring a tight filling. In other embodiments, the protrusions 21 may be prismatic structures or other irregular structures. Furthermore, in this embodiment, multiple protrusions 21 are distributed in a 4×11 matrix, the diameter of each protrusion 21 is 1 mm, and the distance between the center lines of two adjacent protrusions 21 is 3 mm. Optionally, in this embodiment, the material of the protrusions 21 is copper. This arrangement provides good thermal conductivity for the protrusions 21.

[0030] Optionally, in this embodiment, the first hot melt module further includes a first glue-filling area 22 and a first glue-blocking line 23. All protrusions 21 are located within the first glue-filling area 22, and the first glue-blocking line 23 is disposed on one side of the first glue-filling area 22, away from the outer edge 10 of the corresponding core board 1. The core board 1 has a circuit board graphic area, which is located on the side of the first glue-blocking line 23 away from the first glue-filling area 22. By setting the first glue-blocking line 23, the hot melt adhesive in the circuit board graphic area can be prevented from being squeezed away during pressing. Specifically, the width of the first glue-blocking line 23 is greater than or equal to 1 mm.

[0031] Optionally, in this embodiment, the core board 1 is provided with a first edge 24, which surrounds the first glue-filling area 22. By providing the first edge 24, it is convenient to produce the core board 1.

[0032] Optionally, in this embodiment, the top and bottom sides of the hot melt module of the core board 1 away from the outer layer are both second hot melt modules. The second hot melt module includes at least one heat transfer plate 31, which is disposed on the corresponding core board 1. The heat transfer plate 31 is used to transfer heat to the prepreg, and the gaps between the heat transfer plates 31 are used to fill the hot melt adhesive after the prepreg has melted. With this arrangement, it is possible to ensure that the two core boards 1 near the two outer layers are not prone to local deformation, and to avoid bubbling at the hot melt module position on the side of the two core boards 1 near the two outer layers. At the same time, the heat transfer plate 31 is heated by high-frequency electromagnetic wave current to achieve hot melting between the core boards 1 away from the outer layers, so that the core boards 1 away from the outer layers can be bonded into a whole with a better bonding effect. In addition, when the outer layer is laminated at high temperature, the two core plates 1 that are close to the two outer layers are heated at a relatively high temperature, while the core plates 1 that are far from the outer layers are heated at a relatively low temperature. Even if the heat transfer plate 31 has a large heating area, the core plates 1 that are far from the outer layers are heated at a relatively low temperature, so air bubbles will not be generated at the position of the heat transfer plate 31.

[0033] Optionally, in this embodiment, in the two core boards 1 near the two outer layers, the hot melt modules on the side of the two core boards 1 away from the outer layers are both second hot melt modules. This arrangement improves the bonding effect between the core boards 1. In other embodiments, in the two core boards 1 near the two outer layers, the hot melt modules on the side of the two core boards 1 away from the outer layers are both first hot melt modules. This arrangement prevents high temperatures at the location of the hot melt module on the core board near the outer layers, reducing the possibility of air bubbles forming at the hot melt module location.

[0034] Optionally, in this embodiment, the heat transfer plate 31 is a solid plate or a mesh plate. When the heat transfer plate 31 is a solid plate, heat transfer efficiency can be improved. When the heat transfer plate 31 is a mesh plate, the hot melt adhesive from the melted prepreg can enter the holes of the mesh plate, ensuring the flatness of the core plate 1. Furthermore, among the multiple core plates 1 located away from the outer layer, all the heat transfer plates 31 of the multiple core plates 1 are solid plates, or all the heat transfer plates 31 of the multiple core plates 1 are mesh plates, or some core plates 1 are mesh plates and some core plates 1 are solid plates. Optionally, the mesh plate has a length of 19 mm and a width of 5 mm. Optionally, the solid plate has a length of 19 mm and a width of 5 mm. Optionally, the heat transfer plate 31 is made of copper.

[0035] Optionally, in this embodiment, as Figure 3As shown, there are four core boards 1, arranged from top to bottom as a first layer, a second layer, a third layer, and a fourth layer. The first hot-melt module is located on the side of the outermost plate near the top of the first-layer core board 1, bonding the first-layer core board 1 to the top outermost plate. The second hot-melt modules are located on the side of the outermost plate away from the top of the first-layer core board 1, the top and bottom sides of the second-layer core board 1, the top and bottom sides of the third-layer core board 1, and the side of the outermost plate away from the bottom of the fourth-layer core board 1. The heat transfer plates 31 in these second hot-melt modules are all mesh plates, and adjacent second hot-melt modules bond adjacent core boards 1 together. The first hot-melt module is located on the side of the outermost plate near the bottom of the fourth-layer core board 1, bonding the fourth-layer core board 1 to the bottom outermost plate.

[0036] Optionally, in this embodiment, when the heat transfer plate 31 is a mesh plate, the second hot melt module further includes a second glue-filling area 32, which surrounds the mesh plate; the first hot melt module further includes a first glue-filling area 22, where all protrusions 21 are located. The coverage area of ​​the first glue-filling area 22 on the corresponding core plate 1 is smaller than the coverage area of ​​the second glue-filling area 32 on the corresponding core plate 1. It should be noted that the coverage area refers to the area covered by the hot melt adhesive after filling. The coverage area of ​​the first glue-filling area 22 on the corresponding core plate 1 is relatively small, and less hot melt adhesive can be filled in the first glue-filling area 22, resulting in better flatness of the core plate 1 near the outer layer plate. The coverage area of ​​the second glue-filling area 32 on the corresponding core plate 1 is relatively large, and more hot melt adhesive can be filled in the second glue-filling area 32, ensuring reliable adhesion between the core plates 1.

[0037] Optionally, when the heat transfer plate 31 is a mesh plate, the second hot melt module further includes a second adhesive-resistant line 33. The second adhesive-resistant line 33 is disposed on one side of the second adhesive-filling area 32 and is located away from the outer edge 10 of the corresponding core board 1. By providing the second adhesive-resistant line 33, the hot melt adhesive in the circuit board pattern area can be prevented from being squeezed away during pressing. Specifically, the width of the second adhesive-resistant line 33 is greater than or equal to 1 mm.

[0038] Optionally, in this embodiment, when the heat transfer plate 31 is a mesh plate, the second hot-melt module further includes a support member 34. The support member 34 is disposed on the corresponding core plate 1, located within the second glue-filling area 32, and spaced apart from the mesh plate. By providing the support member 34 on the core plate 1, the core plate 1 located above it is supported, ensuring the flatness of the core plate 1 located above it. Specifically, the support member 34 is a cylindrical structure with a diameter of 1 mm.

[0039] Optionally, in this embodiment, the core board 1 is provided with a second edge 35, which surrounds the second glue filling area 32. By providing the second edge 35, it is convenient to produce the core board 1.

[0040] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A circuit board, characterized in that, The device includes two outer layers and multiple core plates (1). All the core plates (1) are sandwiched between the two outer layers. A semi-cured sheet is provided between adjacent core plates. A hot melt module is provided on the top and bottom sides of each core plate (1). In the two core plates (1) close to the two outer layers, the hot melt module on the side of the two core plates (1) close to the outer layers is a first hot melt module. The first hot melt module includes multiple protrusions (21). The multiple protrusions (21) are spaced apart on the corresponding core plates (1). Each protrusion (21) extends along the thickness direction of the core plate (1). The multiple protrusions (21) are used to transfer heat to the semi-cured sheet. The gaps between the multiple protrusions (21) are used to fill the hot melt adhesive after the semi-cured sheet has melted.

2. The circuit board according to claim 1, characterized in that, The protrusions (21) are arranged in a matrix on the corresponding core plate (1).

3. The circuit board according to claim 1, characterized in that, The protrusion (21) is a cylindrical structure.

4. The circuit board according to claim 1, characterized in that, The first hot melt module also includes a first glue filling area (22) and a first glue blocking line (23). All the protrusions (21) are located in the first glue filling area (22). The first glue blocking line (23) is disposed on one side of the first glue filling area (22) and is disposed away from the outer edge (10) of the corresponding core board (1).

5. The circuit board according to claim 1, characterized in that, The hot melt modules on the top and bottom sides of the core plate (1) away from the outer layer are both second hot melt modules. The second hot melt module includes at least one heat transfer plate (31). The heat transfer plate (31) is disposed on the corresponding core plate (1). The heat transfer plate (31) is used to transfer heat to the prepreg. The gaps of the heat transfer plate (31) are used to fill the hot melt adhesive after the prepreg has melted.

6. The circuit board according to claim 5, characterized in that, In the two core plates (1) near the two outer layers, the hot melt module on the side of the two core plates (1) away from the outer layers is the second hot melt module.

7. The circuit board according to claim 6, characterized in that, The heat transfer plate (31) is a solid plate or a mesh plate.

8. The circuit board according to claim 7, characterized in that, When the heat transfer plate (31) is a mesh plate, the second hot melt module further includes a second glue filling area (32), which surrounds the mesh plate; the first hot melt module further includes a first glue filling area (22), all the protrusions (21) are located in the first glue filling area (22), and the coverage area of ​​the first glue filling area (22) on the corresponding core plate (1) is smaller than the coverage area of ​​the second glue filling area (32) on the corresponding core plate (1).

9. The circuit board according to claim 8, characterized in that, When the heat transfer plate (31) is a mesh plate, the second hot melt module further includes a support member (34), the support member (34) is disposed on the corresponding core plate (1), the support member (34) is located in the second glue filling area (32) and is spaced apart from the mesh plate; and / or, When the heat transfer plate (31) is a mesh plate, the second hot melt module further includes a second adhesive barrier line (33), which is disposed on one side of the second adhesive filling area (32) and away from the outer edge (10) of the corresponding core plate (1).

10. The circuit board according to claim 1, characterized in that, The material of the protrusion (21) is copper.

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