Circuit board manufacturing method and circuit board

Abstract

The invention provides a circuit board manufacturing method and a circuit board, and the method comprises the steps: providing a core board and a bonding sheet; a first groove is formed in the core plate, and the high-heating area and the non-high-heating area of the core plate are separated by the first groove; a second groove is formed in the bonding sheet, the second groove is at least partially overlapped with the first groove of the adjacent core plate in the stacking direction, and the first groove and the second groove are used for forming a cavity surrounding the high heating area; filling the first groove and the second groove with a filler; alternately stacking the core boards and the bonding sheets, and pressing to form a mother board; a hole is formed in the mother board, and the filler is exposed; and removing the filler to form a cavity on the mother board. According to the circuit board manufacturing method, the cavity is formed by the first groove and the second groove, the gas in the cavity forms the heat insulation layer, so that heat conduction is hindered, and the influence of a high-heating area on other areas in the circuit board can be reduced by the circuit board manufacturing method. The invention relates to the field of circuit boards.

Description

Technical Field

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

[0002] The heat of the circuit board comes from the heat generated by the current passing through the circuit pattern and the heat generated when the components are working. If the internal heat cannot be dissipated quickly, it will easily accumulate and affect the normal operation of the circuit and other embedded components. In severe cases, it will cause the circuit board to fail.

[0003] Some related technologies embed metal blocks in the circuit board and fit the heat-generating parts, so as to use the metal blocks to efficiently dissipate heat to the outside. However, the position and size of the metal blocks are affected by the circuit pattern design, and the metal blocks will also pass through other sub-boards, occupying the space of the circuit patterns of other layers.

[0004] To this end, Chinese patent CN205082054U and other related technologies set a cavity inside the circuit board, and transfer the heat from the heating components to the heat dissipation components (such as metal blocks) through the flowing heat transfer medium, and then dissipate the heat to the outside.

[0005] However, on the one hand, the heat of the heat-generating components and the heat-dissipating components will still be conducted through the surface of the daughterboard, thereby affecting the surrounding structures (such as circuit patterns or embedded components); on the other hand, this solution requires the processing of cavities before pressing, so only adhesive sheets with no or low adhesive flow can be used, otherwise the flowing resin during pressing will invade or even block the cavity, which makes this solution unsuitable for high-frequency and high-speed circuit boards that require high-flow adhesive sheets. Summary of the invention

[0006] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a circuit board manufacturing method and a circuit board, which helps to reduce the impact of the high-heat-generating area of ​​the circuit board on other areas of the circuit board.

[0007] The circuit board manufacturing method provided in the present application includes providing a core board and a bonding sheet; opening a first groove on the core board, the first groove separating the high heat generation area and the non-high heat generation area of ​​the core board; opening a second groove on the bonding sheet, the second groove at least partially overlaps with the first groove of the adjacent core board in the stacking direction, the first groove and the second groove are used to form a cavity surrounding the high heat generation area; filling the first groove and the second groove with a filler; alternately stacking the core board and the bonding sheet and pressing them together to form a mother board; opening a hole on the mother board to expose the filler; and removing the filler to form the cavity on the mother board.

[0008] According to the circuit board manufacturing method provided by the present application, at least the following technical effects are achieved: on the one hand, the present application utilizes the first groove and the second groove to form a cavity, the first groove separates the high-heating area and the non-high-heating area of ​​the same core board, and the second groove separates the high-heating area and the other core board, and the gas in the cavity forms an insulating layer, thereby hindering the conduction of heat. The circuit board manufacturing method can reduce the impact of the high-heating area on other areas of the circuit board; on the other hand, the cavity is pre-filled with a filler, and the filler is removed after lamination, which can avoid the flow of glue generated during the lamination process from invading the cavity. Therefore, the circuit board is suitable for using high-frequency and high-speed adhesive sheets, and the circuit board manufacturing method has a better scope of application.

[0009] According to some embodiments of the present application, a plurality of holes are opened on the motherboard to form a circuit connecting the cavity and the outside.

[0010] According to some embodiments of the present application, the first grooves of each of the core plates are interconnected through the second grooves.

[0011] According to some embodiments of the present application, before laminating to form the motherboard, the circuit board manufacturing method further includes providing a piezoelectric pump on the core board, wherein an air inlet and an air outlet of the piezoelectric pump are connected to the cavity.

[0012] According to some embodiments of the present application, the first groove surrounds the high heat generation area, and the first groove is disconnected at one side of the high heat generation area.

[0013] According to some embodiments of the present application, the disconnection position is located on a side of the high heat generation area facing the edge of the core board.

[0014] According to some embodiments of the present application, the filler is removed by melting the filler at high temperature or powdering the filler at low temperature.

[0015] According to some embodiments of the present application, the melting point of the filler is greater than or equal to 180°C, and the filler has any of the following characteristics: the melting point of the filler is between 210°C and 270°C; the filler can be powderized at a temperature below 13.2°C.

[0016] According to some embodiments of the present application, the filler includes tin, and the filler is removed by any of the following methods: applying a low temperature to the area where the filler is located, so that the filler is converted into powder and discharged from the hole; or applying a high temperature to the area where the filler is located, so that the filler is melted and discharged from the hole.

[0017] The circuit board provided in the present application is manufactured by the circuit board manufacturing method provided in the present application.

[0018] The circuit board provided in the present application is manufactured by the circuit board manufacturing method provided in the present application, so the circuit board correspondingly has the beneficial effects provided by the circuit board manufacturing method, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide further understanding of the technical solution disclosed in the present application and constitute a part of the specification. Together with the embodiments disclosed in the present application, they are used to explain the technical solution disclosed in the present application and do not constitute a limitation on the technical solution disclosed in the present application.

[0020] Figure 1 It is a schematic diagram of the process of the circuit board manufacturing method of the embodiment of the present application;

[0021] Figure 2 This is a schematic diagram of the structure of a circuit board manufactured by the circuit board manufacturing method according to an embodiment of the present application;

[0022] Figure 3 This is a schematic diagram of the structure of a circuit board manufactured by the circuit board manufacturing method according to an embodiment of the present application;

[0023] Figure 4 This is a schematic diagram of the structure of a circuit board manufactured by the circuit board manufacturing method according to an embodiment of the present application;

[0024] Figure 5 yes Figures 2 to 4 A schematic diagram of the structure of the filler used in the circuit board embodiment shown;

[0025] Figure 6 yes Figures 2 to 4 A schematic diagram of the structure of the filler used in the circuit board embodiment shown.

[0026] Reference numerals:

[0027] Core board 100, first slot 110, heat generating components 120;

[0028] Adhesive sheet 200, second groove 210;

[0029] Filler 300;

[0030] Hole 400. DETAILED DESCRIPTION

[0031] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0032] In the description of the present application, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do 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 should not be understood as a limitation on the present application.

[0033] In the description of this application, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0034] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0035] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0036] The inner circuit pattern of the circuit board has the risk of heat accumulation and circuit board failure due to poor heat dissipation. To this end, some related technologies embed metal blocks in the circuit board to quickly conduct heat to the outer surface through the metal blocks to avoid heat accumulation.

[0037] However, on the one hand, the metal block needs to occupy a large space, so the location of the metal block is limited, and it also affects the design of the circuit pattern.

[0038] On the other hand, the heat in the high-heat-generating area will still be conducted through the core board. While the metal block is conducting heat outward, it is also conducting heat with the sub-board (core board and bonding sheet) that is in contact with the metal block. Therefore, other areas of the circuit board will inevitably be affected by the heat during the heat dissipation process.

[0039] Some related technologies form a cavity in the circuit board, use the cavity as a flow channel, and connect the heat sink (such as a metal block) and the high heat generation area through heat transfer through the flow channel, so that the location of the heat sink is more flexible. The heat sink can be buried in a position different from the high heat generation area, or it can be set outside the circuit board.

[0040] However, this solution still has some problems. On the one hand, the flow channel cannot solve the problem of heat conduction through the core board in the high-heat area; on the other hand, if liquid is used as the heat transfer medium, the heat will inevitably be transferred to the surrounding circuit board structure during the flow of the liquid.

[0041] To this end, the present application provides a circuit board manufacturing method, which helps to reduce the impact of high-heat-generating areas of the circuit board on other areas of the circuit board.

[0042] In addition, the present application also provides a circuit board manufactured using the circuit board manufacturing method.

[0043] Reference Figure 1 , and combined with Figure 2 , Figure 3 , Figure 4 The circuit board embodiment shown in the figure, the circuit board manufacturing method of the embodiment of the present application includes the following steps:

[0044] Step S110 : providing a core board 100 and a bonding sheet 200 .

[0045] It is understood that the circuit board in the present application is a multi-layer board, which is formed by alternately stacking and laminating a core board 100 and an adhesive sheet 200, and the circuit board has at least three layers (two core boards 100 sandwiching a layer of adhesive sheet 200). The core board 100 is a single-sided or double-sided copper-clad board, and a circuit pattern is made on the core board 100.

[0046] According to the circuit design, there may be areas on the circuit pattern where the circuit density is relatively high or where the heat generating components 120 are arranged. These areas may be high heat generating areas of the core board 100. Figure 2 and Figure 4 In the illustrated circuit board embodiment, the area where the heat generating components 120 are disposed is regarded as a high heat generating area.

[0047] Step S120 : opening a first groove 110 on the core plate 100 , wherein the first groove 110 separates a high heat generation area and a non-high heat generation area of ​​the core plate 100 .

[0048] Step S400: a second groove 210 is formed on the bonding sheet 200. The second groove 210 at least partially overlaps with the first groove 110 of the adjacent core plate 100 in the stacking direction. The first groove 110 and the second groove 210 are used to form a cavity surrounding a high heat generation area.

[0049] The first groove 110 separates the high-heating area and the non-high-heating area of ​​the same core board 100, and the second groove 210 separates the high-heating area and another core board 100. The gas in the cavity forms an insulating layer, thereby hindering the conduction of heat. Therefore, the circuit board manufacturing method can reduce the impact of the high-heating area on other areas in the circuit board.

[0050] Figure 3 and Figure 4 The shape of the cavity formed by the first groove 110 and the second groove 210 is exemplarily shown. Figure 3 and Figure 4 In the stacking direction, the projection of the high heat generation area at least partially falls into (preferably completely falls into) the range of the adjacent second groove 210, so that the second groove 210 can play the role of separating the high heat generation area and another core plate 100.

[0051] In order to fully block the heat conduction between the high-heating area and the non-high-heating area, the first groove 110 is preferably surrounded by the high-heating area, so as to produce a separation effect in multiple directions. However, the high-heating area cannot be isolated or suspended. The high-heating area needs to be connected to the non-high-heating area through a circuit pattern. Figure 1 , the first slots 110 need to be disconnected at one side of the high heat generation area, thereby allowing the circuit pattern to pass through between the first slots 110 .

[0052] At this time, the heat in the high heat generation area can be conducted outward from the position where the first groove 110 is disconnected. In order to extend the distance of heat conduction to the main body of the non-high heat generation area, optionally, in some implementations, the disconnection position is located on the side of the high heat generation area toward the edge of the core plate 100.

[0053] Furthermore, the first slot 110 may extend to a position close to the edge of the core plate 100 , so that heat must first be conducted from the high heat generation area to the edge of the core plate 100 before bypassing the first slot 110 and being conducted to the core plate 100 outside the first slot 110 .

[0054] Step S140 : filling the first trench 110 and the second trench 210 with a filler 300 .

[0055] Figure 5 The shape of the filler used to fill the first groove 110 and the second groove 210 is shown as an example. Since there may be multiple high heat generation areas on a single core board 100 in the present application, the high heat generation areas on different core boards 100 may not overlap in the stacking direction, so the shape of the filler 300 may be relatively complex. Figure 6 In some embodiments, corresponding fillers 300 may be made for each layer of the core board 100 and the bonding sheet 200 .

[0056] Step S150: alternately stacking the core boards 100 and the bonding sheets 200 and pressing them together to form a mother board.

[0057] It is understandable that during the lamination process, the resin in the bonding sheet 200 will first be softened by heat to form a flow glue, and then polymerized and solidified. Generally speaking, the better the high-frequency and high-speed performance of the bonding sheet 200 (that is, the lower the dielectric constant Dk and dielectric loss Df), the better the fluidity during lamination. Since the cavity is pre-filled with the filler 300, the flow glue generated during the lamination process can be prevented from occupying the cavity. Therefore, the circuit board is suitable for the use of high-frequency and high-speed bonding sheets, and the circuit board manufacturing method has a better scope of application.

[0058] Step S160 : opening a hole 400 on the motherboard to expose the filler 300 .

[0059] The hole 400 extends from the surface of the motherboard to the area where the cavity is located. Figure 4 In the illustrated embodiment, the bonding sheet 200 adjacent to the outermost core panel 100 also has a second groove 210, so the hole 400 only needs to penetrate the outermost core panel 100 to expose the filler 300. In other embodiments, it is not ruled out that the hole 400 may need to penetrate multiple layers of core panels 100 and bonding sheets 200, and the present application does not impose any restrictions on this.

[0060] Step S170: removing the filler 300 to form a cavity on the motherboard.

[0061] In the related art, the most common way to remove the embedded filler 300 is to open a hole 400 (generally referred to as a window) to completely expose the filler 300 , thereby directly taking the filler 300 out of the hole 400 .

[0062] However, in the present application, since the filler in the second groove 210 overlaps with the high heat generation area, other methods are required to remove the filler.

[0063] Optionally, ink can be used as filler 300 to fill the cavity, and then the ink can be removed by etching with liquid medicine after lamination. However, liquid medicine can easily damage the circuit pattern of the circuit board, and for cavities with complex shapes and narrow local dimensions (such as the present application Figure 4 In the embodiment shown in the figure), there are problems such as difficulty in exchanging the liquid medicine and low exchange efficiency, which leads to increased time and reduced yield.

[0064] To this end, in some embodiments, the filler 300 is removed by melting the filler 300 at high temperature or powdering it at low temperature. Since melting and powdering are physical changes, no acidic or alkaline solution is needed, thus avoiding damage to the circuit pattern of the circuit board. Since melting or powdering is triggered by the temperature change of the filler 300, it is more suitable for removing the filler 300 in a complex cavity, and will not be affected by the difficulty of exchanging the solution, and the efficiency and reliability of removing the filler 300 are higher.

[0065] In summary, compared with using liquid medicine to remove the filler 300 , removing the filler 300 by high-temperature melting or low-temperature powdering can improve efficiency and yield.

[0066] Specifically, considering that high temperature is also generated during the pressing process, in order to prevent the filler 300 from melting during pressing and causing the glue to flow into the cavity, the melting point of the filler 300 should be greater than or equal to 180°C.

[0067] In the embodiment of removing the filler 300 by high temperature melting, in order to reduce the damage to the circuit board during the melting process, the melting point of the filler 300 should be lower than the maximum temperature that the circuit board can withstand. Exemplarily, the melting point of the filler 300 can be selected between 210°C and 270°C.

[0068] In the embodiment of removing the filler 300 by low temperature pulverization, in order to avoid pulverization at room temperature, the pulverization temperature of the filler 300 should be lower than room temperature. Exemplarily, the filler 300 can be pulverized at a temperature lower than 13.2°C.

[0069] In some embodiments, the filler 300 includes tin (tin alone or a tin alloy), thereby satisfying the above requirements for the filler 300 .

[0070] It is understandable that metallic tin has three allotropes: gray tin, white tin and brittle tin. Its Mohs hardness is only 3.75, making it one of the softest metals with good ductility but poor ductility. Within the temperature range of 13.2℃-161℃, the properties of tin are relatively stable, with a tetragonal lattice, called "white tin".

[0071] When the ambient temperature is lower than 13.2℃, the atoms in the tin crystal will rearrange and gradually change from a tetragonal lattice to a cubic lattice. This change changes the tin into a gray powder, which is "gray tin". At a temperature of -30℃, the crystal transformation speed reaches its maximum, and the tin block quickly turns into powder. The transformation from white tin to gray tin is called tin plague.

[0072] When the temperature is above 161℃, white tin turns into orthorhombic tin with orthorhombic crystal structure. Orthorhombic tin is very brittle and will break when knocked. Its brittleness increases and its ductility is poor, so it is called "brittle tin".

[0073] When the temperature is above 232°C, tin melts.

[0074] First, using tin as the filler 300 can meet the requirements of press-fitting.

[0075] At the beginning of pressing, the pressure will be increased first. When it reaches the highest pressure, the temperature is about 110℃. At this time, the tin is in a stable white tin state, providing reliable support.

[0076] Thereafter, the temperature is continuously raised on the basis of constant pressure, and the fluidity of the bonding sheet 200 is further enhanced. When the temperature reaches about 140°C, the viscosity of the bonding sheet 200 is the lowest and the fluidity is the strongest. During this process, the tin can continue to remain in the state of white tin, and the hardness of the tin can withstand the squeezing force of the flowing glue, thereby effectively blocking the flowing glue and preventing the area that will serve as the cavity from being occupied by the flowing glue.

[0077] After that, the temperature continues to rise, the viscosity of the bonding sheet 200 gradually increases, the fluidity deteriorates and solidifies, and when it reaches 160°C, the tin begins to become unstable and turns into brittle tin, but at this time the glue flow has basically entered a solidified state, and will not cause a large squeeze or other impact on the area where the tin is located (that is, the area serving as the cavity), ensuring that the area is not occupied. At the same time, since the circuit board is in a stable placement state during the hot pressing process, the filler 300 is not impacted, so the brittle tin will not be broken and cause the glue flow to be squeezed in turn.

[0078] Continue to raise the temperature to about 200℃, the metal tin begins to soften gradually. At this time, the flow glue has solidified and will not affect the area where the tin is located.

[0079] In summary, based on the physical properties of tin, the entire pressing process will not affect the space occupied by tin, and tin as the filler 300 can meet the requirements of endurance of the pressing process.

[0080] Secondly, tin can be removed by high-temperature melting. Taking tin as an example, heating to slightly above 232°C can turn tin into liquid. At this time, it is only necessary to process the hole 400 connecting the cavity area, and the liquid tin can be easily discharged from the hole 400. The position of the hole 400 is not affected by the shape of the filler 300, and the size of the hole 400 is not affected by the size of the filler 300. Since 232°C is only slightly higher than the temperature during pressing (for example, 200°C), it is not easy to cause damage to the structure on the circuit board. Since liquid tin is fluid, the complexity of the shape of the cavity (for example, a mesh-like cavity) will not affect the discharge of the filler 300.

[0081] Finally, tin can also be removed by low-temperature powderization. Taking tin as an example, cooling to below 13.2°C can cause tin to undergo tin quenching and transform into a powder state. Cooling to below -30°C can accelerate this process. At this time, only the hole 400 connecting the cavity area needs to be processed to conveniently discharge the powdered tin from the hole 400. The position of the hole 400 is not affected by the shape of the filler, and the size of the hole 400 is not affected by the size of the filler.

[0082] It is understandable that for some temperature-sensitive circuit boards, such as those with embedded precision components, the melting temperature may exceed the tolerance of the circuit board. However, 13.2°C will hardly have a negative impact on the circuit board. The low-temperature powder removal method can better avoid the problem of damaging the circuit board and more reliably remove the filler 300.

[0083] It should be pointed out that in the embodiments of the present application, tin is the main component of the filler 300, but the filler 300 is not required to be a single tin substance. It is allowed to add some other components to the filler 300 (that is, a tin alloy that meets the requirements is used as the filler 300) to adjust the physical properties of the filler 300, as long as it does not hinder the removal of the filler 300 by heating or cooling.

[0084] Optionally, the melting point of the filler 300 or the temperature at which tin poisoning occurs may be adjusted by adding other components according to the needs of the process flow.

[0085] For example, if there are other low-temperature links in the process, in order to prevent the filler 300 from being powdered prematurely, the occurrence temperature of tin pest may be reduced by adding aluminum or zinc.

[0086] Alternatively, ferromagnetic metal powder may be added to the filler 300 so that the filler 300 can be selectively heated locally and directionally by high-frequency electromagnetic heating, thereby reducing the heat received by other areas of the circuit board during the melting process and reducing the impact on other areas.

[0087] For example, some iron powder can be sprinkled on the surface of the tin block to form the required filler 300; or some iron powder can be sandwiched between two tin blocks to form the required filler 300; or, tin can be melted in a mold, iron powder can be added and stirred evenly, and the required filler 300 can be formed after solidification.

[0088] Optionally, in step S170 , auxiliary means may be used to facilitate the discharge of the powdered and melted filler 300 .

[0089] Optionally, a plurality of holes 400 are drilled on the motherboard, and positive pressure or negative pressure is applied to some of the holes 400 to promote the discharge of the filler 300. The function of the plurality of holes 400 is to form a fluid loop to prevent the pressure difference from hindering the discharge of the filler 300 (especially in the method of temperature increase removal). The pressure can be applied continuously or intermittently, and can be always positive pressure / negative pressure, or positive pressure and negative pressure can be applied alternately. The specific pressurization method can be determined based on the experimental results on the specific circuit board, that is, it is determined comprehensively based on factors such as the position of the hole 400 (front or side), the shape of the filler 300, and the present application does not limit this.

[0090] Optionally, for the cooling and removal method, since the fluidity of powder is lower than that of liquid, a solution can be injected into the area where the filler 300 is located through the hole 400, and the powdered filler 300 can be taken out with the solution to avoid residue. It should be noted that since the filler 300 has been powdered, even if it is insoluble in the solution, it can be taken out in the form of turbid liquid, so it is not required that the filler 300 must be soluble in the solution, but it is necessary to ensure that the solution will not react with other structures of the circuit board.

[0091] Optionally, regardless of whether the removal is performed by increasing the temperature or decreasing the temperature, in order to avoid residues in the cavity, it is preferred to drill a plurality of holes 400 on the motherboard, and clean the cavity with a cleaning liquid (such as deionized water) after removing the filler 300 .

[0092] It can be noted that opening a plurality of holes 400 on the motherboard can form a loop between the cavity and the outside, so in addition to using the cavity for heat insulation, the cavity can also be used to help the high-heat area dissipate heat. That is, the gas enters the cavity from one part of the holes 400 and leaves the cavity from another part of the holes 400, and the heat is dissipated to the outside of the circuit board by heat convection.

[0093] It should be pointed out that holes 400 are required in multiple steps of the circuit board manufacturing method, such as the step of removing the filler 300, the step of cleaning the cavity, and the step of constructing convection heat dissipation. The holes 400 in these steps can be the same (that is, reused holes 400) or different (that is, each step has a dedicated hole 400), and the present application does not impose any restrictions on this.

[0094] In some embodiments, the first grooves 110 of each core plate 100 are interconnected through the second grooves 210. That is, the small cavities corresponding to different high-heat-generating areas are connected together through the second grooves 210 to form an overall large cavity, thereby increasing the volume of the cavity and being more suitable for gas flow in the cavity.

[0095] In some embodiments, before laminating to form a motherboard, the circuit board manufacturing method further includes providing a piezoelectric pump on the core board 100, wherein the air inlet and the air outlet of the piezoelectric pump are connected to the cavity. By providing an embedded piezoelectric pump, the piezoelectric pump is electrically connected to the circuit pattern of the core board 100, and the piezoelectric pump is powered by the circuit pattern, so that when the circuit board is running, the circuit board can spontaneously generate airflow through the cavity with the help of the piezoelectric pump without connecting an external gas generating device, thereby improving the use effect of the circuit board.

[0096] In some selectable embodiments, the function / operation mentioned in the block diagram may not occur in the order mentioned in the operation diagram. For example, depending on the function / operation involved, the two boxes shown in succession can actually be executed substantially simultaneously or the boxes can sometimes be executed in reverse order. In addition, the embodiment presented and described in the flow chart of the application is provided by way of example, for the purpose of providing a more comprehensive understanding of technology. The disclosed method is not limited to the operation and logic flow presented herein. Selectable embodiments are expected, wherein the order of various operations is changed and the sub-operation of a part described as a larger operation is performed independently.

[0097] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A method for manufacturing a circuit board, characterized in that: include: Provide core board and bonding sheet; A first groove is provided on the core plate, wherein the first groove separates a high-heat-generating area and a non-high-heat-generating area of ​​the core plate; A second groove is provided on the bonding sheet, wherein the second groove at least partially overlaps with the first groove of the adjacent core plate in the stacking direction, and the first groove and the second groove are used to form a cavity surrounding the high heat generation area; filling the first groove and the second groove with a filler; Alternately stacking the core plates and the bonding sheets, and pressing them together to form a mother plate; Opening a hole in the motherboard to expose the filler; The filler is removed to form the cavity on the mother board.

2. The method for manufacturing a circuit board according to claim 1, characterized in that: A plurality of holes are opened on the motherboard to form a circuit connecting the cavity and the outside.

3. The method for manufacturing a circuit board according to claim 2, characterized in that: The first grooves of the core plates are connected to each other through the second grooves.

4. The method for manufacturing a circuit board according to claim 1 or 2, characterized in that: Before the motherboard is formed by lamination, the circuit board manufacturing method further includes arranging a piezoelectric pump on the core board, wherein an air inlet and an air outlet of the piezoelectric pump are connected to the cavity.

5. The method for manufacturing a circuit board according to claim 1, characterized in that: The first groove surrounds the high heat generation area, and the first groove is disconnected at one side of the high heat generation area.

6. The method for manufacturing a circuit board according to claim 5, characterized in that: The disconnection position is located on the side of the high heat generation area facing the edge of the core plate.

7. The method for manufacturing a circuit board according to claim 1, characterized in that: The filler is removed by melting it at high temperature or powdering it at low temperature.

8. The method for manufacturing a circuit board according to claim 7, characterized in that: The melting point of the filler is greater than or equal to 180° C., and the filler has any one of the following characteristics: the melting point of the filler is between 210° C. and 270° C.; the filler can be powderized at a temperature lower than 13.2° C.

9. The method for manufacturing a circuit board according to claim 8, characterized in that: The filler includes tin, and the filler is removed by any of the following methods: applying low temperature to the area where the filler is located, so that the filler is converted into powder and discharged from the hole; or applying high temperature to the area where the filler is located, so that the filler is melted and discharged from the hole.

10. A circuit board, characterized in that: The circuit board is manufactured by the circuit board manufacturing method according to any one of claims 1 to 9.

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