PCB circuit board with air medium cavity and manufacturing method thereof

Abstract

This invention discloses a PCB circuit board with an air dielectric cavity and its manufacturing method, relating to the field of circuit board technology. The PCB circuit board includes an air dielectric cavity disposed on the PCB circuit board, with embedded grooves surrounding the air dielectric cavity, and an embedded substrate installed within the embedded grooves. The embedded substrate is made by etching copper foil from a copper-clad laminate and then laminating a prepreg, or by embedding copper. Using the embedded substrate as the lamination support point for the air cavity effectively prevents lamination collapse. Furthermore, due to the simplicity of its manufacturing, the embedded substrate is applicable to various material types, including ordinary materials, high-speed materials, and high-frequency materials, thus having a wide range of applications. In addition to serving as a support point for the air cavity and preventing collapse, the embedded substrate, due to its characteristics, will not deform the vulcanized adhesive during lamination, resulting in less compression of the air cavity after lamination, which facilitates simulation calculations by SI engineers.

Description

Technical Field

[0001] This invention relates to the field of circuit board technology, specifically to a PCB circuit board containing an air dielectric cavity and its manufacturing method. Background Technology

[0002] Printed circuit boards (PCBs) are fundamental components of the electronics industry. They typically consist of an insulating substrate (such as fiberglass) and conductive copper foil covering its surface. The circuitry formed on the copper foil through processes like etching provides fixed mounting positions for various electronic components (such as resistors, capacitors, and chips) and enables electrical connections between them. Simply put, it serves both to support electronic components and to transmit current.

[0003] An air-cavity PCB is a special type of printed circuit board that utilizes the extremely low dielectric constant and loss factor of air to significantly reduce signal transmission loss and delay by removing the dielectric material from the inner core board or adhesive layer to create an air-filled cavity structure. This design effectively reduces energy loss and parasitic effects in traditional solid-state media by exposing or suspending high-frequency signal lines above the air cavity, and optimizes the accuracy of impedance control.

[0004] Currently, there are roughly the following types of models for creating air as a medium:

[0005] 1. Directly create windows on the outer layer of the PCB board and use EMI materials to shield the influence of external signals.

[0006] Its advantages are:

[0007] 1. The stacking structure is simple and the process time is short, which can be applied to the production of three- and four-layer boards.

[0008] 2. Since the laser window is opened after pressing, there is no problem of the air cavity collapsing after pressing.

[0009] Its disadvantages are:

[0010] 1. It has significant limitations and cannot be applied to multilayer boards.

[0011] 2. Since the outer copper layer and the interconnect layer are etched together with the laser to create windows, it is necessary to add EMI to isolate external signals, which increases the manufacturing cost.

[0012] Second, during the pressing process, windows are made in the steel plate. That is, during the pressing process, windows are made in the corresponding air cavities on the pressing steel plate, and the air cavities are not pressed with a large force.

[0013] Its advantages are:

[0014] 1. Since no etching is performed on the outer copper foil, the influence of external signals can be effectively isolated, eliminating the need for additional consumables for isolation and saving costs.

[0015] 2. Since the steel plate has a window, the collapse at the corresponding air cavity is not severe, and the size of the air cavity can be estimated for simulation calculation.

[0016] Its disadvantages are:

[0017] 1. Poor pressing uniformity will significantly affect the uniformity of the medium.

[0018] 2. There is a risk of the steel plate bursting at the edge of the window opening.

[0019] Currently, the most pressing issue in manufacturing sheet materials using air as a medium is that excessive pressure during the pressing process can compress the air cavity, making it difficult to accurately calculate its size. In severe cases, this could even lead to the risk of collapse or sheet explosion. Summary of the Invention

[0020] The current lamination process for PCBs with air-filled dielectric cavities suffers from the problem that excessive pressure can compress the air cavity, making it difficult to accurately calculate its size and potentially leading to collapse and board explosion. The present invention aims to provide a PCB with an air-filled dielectric cavity and its manufacturing method. This PCB uses an embedded substrate as the lamination point for the air cavity, effectively preventing lamination collapse. Furthermore, since the substrate does not deform or leak adhesive during lamination, the degree of air cavity compression after lamination is minimal, facilitating simulation calculations by SI engineers.

[0021] This invention is achieved through the following technical solution:

[0022] In a first aspect, this application provides a PCB circuit board with an air dielectric cavity, including an air dielectric cavity disposed on the PCB circuit board, an embedded groove being disposed around the air dielectric cavity, and an embedded substrate being installed in the embedded groove; the embedded substrate is made by etching copper foil from a copper-clad laminate and then laminating a prepreg or by using embedded copper.

[0023] The embedded substrate is a type of substrate material whose thickness can be adjusted during lamination by modifying the thickness of the prepreg to meet the required thickness. Its size can be directly determined by routing the board after lamination and etching. In addition, the size of the embedded substrate can be determined according to the actual PCB design. For PCBs with denser trace layouts, smaller embedded substrates can be designed for the lamination process.

[0024] In actual PCB design, if heat dissipation is involved, the embedded substrate can be replaced with embedded copper, which can simultaneously meet the heat dissipation requirements and the ability to support the air cavity.

[0025] In one specific embodiment, multiple embedding grooves are provided, and an embedding substrate is installed in each embedding groove.

[0026] In one specific embodiment, the distance between the embedded substrate and the air medium cavity is L, where 0.2mm≤L≤2mm.

[0027] Among them, the distance between the embedded substrate and the air dielectric cavity is ≥0.2mm, which can avoid the cavity being broken by the routing precision; the distance between the embedded substrate and the air dielectric cavity is ≤2mm, which can avoid the reduced support effect of the embedded substrate if the distance is too far; the size and position of the embedded substrate can be flexibly adjusted according to the PCB board pattern.

[0028] In one specific embodiment, the inner layer of the embedded substrate is etched with positioning points.

[0029] The etching of the inner layer of the embedded substrate requires the creation of positioning points for each process to facilitate positioning in subsequent processes; apart from the positioning content, all other copper foils must be etched away, and care must be taken to ensure that there is no residual copper.

[0030] In one specific embodiment, when the layer containing the air dielectric cavity has electrical isolation requirements, copper plating is performed on it before placing the embedded substrate.

[0031] In one specific embodiment, the target thickness of the embedded substrate is determined by the following formula: Embedded substrate thickness = 96% × theoretical board thickness + 0.05 mm; the thickness tolerance requirement is ±0.015 mm.

[0032] In one specific embodiment, the tolerance requirement for the length and width of the embedded substrate is ±0.03mm. The minimum size of the embedded substrate is 2cm*2cm, and the maximum support distance between any two embedded substrates is approximately 6.84cm. The design can be based on a minimum edge distance of 6.5cm for the embedded substrates.

[0033] In one specific embodiment, the method for manufacturing the embedded substrate includes the following steps:

[0034] The inner layers of the core board are etched to remove redundant copper foil, then OPE punching is performed, and then prepreg is selected for lamination. After lamination, drilling is performed.

[0035] Based on the dimensions of the embedded substrate, the die is made into grooves, and then the die is pre-stacked and laminated to obtain the embedded substrate for embedding in the embedded groove of the PCB circuit board.

[0036] In the prepreg process, the prepreg is first punched to create corresponding fusion positioning holes and rivet holes before being slotted. Positioning holes are used for positioning, and the prepreg slot is required to be 0.15mm larger on each side than the embedded substrate. When slotting the prepreg, a roughing and finishing process is used. The roughing process leaves a 0.05mm margin on each side for finishing. The roughing cutter is limited to 2m, and the finishing cutter is limited to 5m. The finishing process uses a double-edged milling cutter at a normal feed rate.

[0037] Among them, the routing process uses the holes punched by OPE as positioning holes. The selection of holes needs to be foolproof. The core board window size is required to be 0.1mm larger on each side than the embedded substrate size. When routing the core board window, rough routing + fine routing is used. The rough routing leaves 0.05mm on each side for fine routing. The routing strip in the waste area is designed to handle the routing fragments. The stacking height is controlled to ≤3mm. A cover plate must be added when routing the board.

[0038] In this process, the slots are machined according to the size of the embedded substrate. Multiple embedded substrates of different sizes can be machined from a single embedded substrate according to actual requirements, thereby improving the utilization rate of a single substrate and reducing manufacturing costs.

[0039] If the finished PCB board is relatively thin, a high-thickness core board can be used directly to manufacture the embedded substrate. In this case, the embedded substrate can directly use OPE holes as positioning holes and router slots, without the need for pressing operations.

[0040] Secondly, this application provides a method for manufacturing a PCB circuit board containing an air dielectric cavity, comprising the following steps:

[0041] The embedded substrate is fabricated using the fabrication method described in claim 8;

[0042] On the core layer of the PCB, corresponding to the preset air dielectric cavity position, a window is made to form the core board window area;

[0043] On the prepreg layer of the main PCB material, a window is made corresponding to the core board window area to form the prepreg window area;

[0044] An embedded substrate is placed into the window area of ​​the prepreg and then pressed together. During the pressing process, the embedded substrate acts as a rigid support point, so that the window area of ​​the prepreg forms a dimensionally stable air medium cavity after pressing.

[0045] In one specific embodiment, the dimensional tolerance requirement for the window area of ​​the core board is ±0.03mm.

[0046] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0047] (1) The present invention uses an embedded substrate as a pressing support point for the air cavity, which effectively prevents the problem of pressing collapse. At the same time, the embedded substrate is simple to manufacture and can be applied to various material types such as ordinary materials, high-speed materials, and high-frequency materials, with a wide range of applications. In addition, the embedded substrate in the present invention can not only serve as a support point for the air cavity to avoid the problem of air cavity collapse, but also, due to the characteristics of the embedded substrate, will no longer deform the vulcanized adhesive during pressing. Therefore, the degree of air cavity compression after pressing is small, which makes it convenient for SI engineers to perform simulation calculations.

[0048] (2) The embedded substrate in this invention can be replaced by any embedded product, with a high degree of freedom. For example, in PCB circuit boards with heat dissipation requirements, the embedded substrate can be replaced by embedded copper for filling, which also serves as heat dissipation and support.

[0049] (3) The manufacturing cost of the present invention is low. Since the embedded substrate can be directly supported by the raw material core board and the prepreg, no additional cost is required. Attached Figure Description

[0050] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0051] Figure 1 This is a top view of a PCB circuit board containing an air dielectric cavity according to the present invention;

[0052] Figure 2 This is a cross-sectional view of a PCB circuit board containing an air dielectric cavity according to the present invention.

[0053] Figure label:

[0054] 01-Positioning hole, 02-Embedded substrate, 03-Air dielectric cavity, 04-Anti-foolproof hole, 05-PCB circuit board, 06-Core board, 07-Prepreg, 08-Copper surface, 09-Circuit. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0056] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0057] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples.

[0058] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0059] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0060] Example 1

[0061] like Figures 1-2 As shown, this embodiment provides a PCB circuit board with an air dielectric cavity, including an air dielectric cavity 03 disposed on the PCB circuit board 05. Four embedded grooves are disposed around the air dielectric cavity 03, and an embedded substrate 02 is installed in each embedded groove. The embedded substrate 02 is made by etching copper foil on a copper-clad laminate and then pressing a prepreg 07 onto it.

[0062] Specifically, the embedded substrate 02 is a substrate material whose thickness can be adjusted during lamination by modifying the thickness of the prepreg 07 according to the required thickness. Its size can be directly determined after lamination and etching. Furthermore, the size of the embedded substrate 02 can be determined based on the actual PCB design. PCBs with denser trace layouts can use a smaller embedded substrate 02 for the lamination process. In actual PCB design, if heat dissipation is a concern, the embedded substrate 02 can be replaced with embedded copper, simultaneously addressing both heat dissipation requirements and the ability to support air cavities.

[0063] Specifically, the distance between the embedded substrate 02 and the air dielectric cavity 03 is L, where 0.2mm ≤ L ≤ 2mm. A distance of ≥ 0.2mm between the embedded substrate 02 and the air dielectric cavity 03 avoids damage to the cavity due to PCB routing precision issues; a distance of ≤ 2mm between the embedded substrate 02 and the air dielectric cavity 03 prevents a decrease in support due to excessive distance; the size and position of the embedded substrate 02 can be flexibly adjusted according to the PCB board pattern.

[0064] Specifically, the inner layer of the embedded substrate 02 has positioning points etched. The etching of the inner layer of the embedded substrate 02 requires the creation of positioning points for each process to facilitate positioning in subsequent processes; apart from the positioning points, all other copper foil must be etched away, and care must be taken to ensure that there is no residual copper.

[0065] Specifically, when the air dielectric cavity 03 layer has electrical isolation requirements, copper plating is performed on it before placing the embedded substrate 02.

[0066] Specifically, the target thickness of the embedded substrate 02 is determined by the following formula: Embedded substrate 02 thickness = 96% × theoretical board thickness + 0.05mm; the thickness tolerance requirement is ±0.015mm. The tolerance requirements for the length and width of the embedded substrate 02 are ±0.03mm. The minimum size of the embedded substrate 02 is 2cm * 2cm, and the maximum support distance between two embedded substrates 02 is approximately 6.84cm. The design can be based on a minimum edge distance of 6.5cm for the embedded substrate 02.

[0067] The PCB circuit board 05 uses an embedded substrate 02 as the pressing support point for the air cavity, which effectively prevents the problem of pressing collapse. At the same time, due to the simple manufacturing of the embedded substrate 02, it can be applied to various material types such as ordinary materials, high-speed materials, and high-frequency materials, and has a wide range of applications. Moreover, in addition to serving as a support point for the air cavity and avoiding the problem of air cavity collapse, the embedded substrate 02 in this invention will not deform the vulcanized adhesive during pressing due to its characteristics. Therefore, the degree of air cavity compression after pressing is small, which can facilitate SI engineers to perform simulation calculations.

[0068] Example 2

[0069] This embodiment provides a method for manufacturing a PCB circuit board containing an air dielectric cavity, the specific steps of which are as follows:

[0070] S1. Preparation of embedded substrate

[0071] S1-1 Selection of Embedded Substrate

[0072] S1-1-1 If the finished PCB board is relatively thin, a high-thickness core board 06 can be used directly to make the embedded substrate 02. At this time, the embedded substrate 02 can directly use the OPE holes as positioning holes 01 and the routing slots of the routing board, without the need for pressing operations.

[0073] S1-1-2. The dimensions of the embedded substrate 02 can be defined according to the actual PCB design. For PCBs with denser trace layout, a smaller embedded substrate 02 can be designed for the lamination process. Its dimensional requirements are as follows: the thickness of the embedded substrate 02 = theoretical board thickness with 96% residual copper rate + 0.05mm, with a tolerance of ±0.015mm; the length of the embedded substrate 02 is the original size required, with a tolerance of ±0.03mm; the width of the embedded substrate 02 is the original size required, with a tolerance of ±0.03mm.

[0074] S1-1-3. Embedded substrate 02 can be replaced with any embedded product according to the needs of the PCB board. If the PCB has heat dissipation requirements, embedded substrate 02 can be replaced with embedded copper within the design limits.

[0075] S1-2, Design of Embedded Substrate

[0076] The embedded substrate 02 should be at least 0.2mm away from the cavity to avoid damage to the cavity due to the precision of the routing process; the embedded substrate 02 should be at least 2mm away from the cavity to avoid reduced support if the embedded substrate 02 is too far away; the size and position of the embedded substrate 02 can be flexibly adjusted according to the PCB board pattern, such as... Figure 1 As shown.

[0077] S1-3, Inner layer etching of embedded substrate

[0078] The etching of the inner layer of the embedded substrate 02 requires the creation of positioning points for each process to facilitate positioning in subsequent processes; apart from the positioning content, all other copper foils need to be etched away, and care must be taken to ensure that there is no residual copper.

[0079] S1-4, OPE punching of embedded substrate

[0080] S1-5, Lamination of embedded substrate

[0081] The thickness of the embedded substrate 02 needs to be estimated for lamination (the thickness of the embedded substrate 02 = theoretical board thickness with 96% residual copper rate + 0.05mm, with a tolerance of ±0.015mm). The thickness of the prepreg 07 is selected for lamination based on the thickness. There are no special requirements for the selection of the prepreg 07. Various types of prepregs of the same material can be used.

[0082] S1-6, Drilling positioning holes 01 for embedded substrate

[0083] S1-7, Routing groove for embedded substrate

[0084] The embedded substrate 02 is serrated according to its dimensions. The length of the embedded substrate 02 is the same as the original size, with a tolerance of ±0.03mm. The width of the embedded substrate 02 is the same as the original size, with a tolerance of ±0.03mm. Multiple embedded substrates 02 of different sizes can be serrated from a single substrate according to actual requirements to improve the utilization rate of a single substrate and reduce manufacturing costs.

[0085] S1-8, Pressing and Pre-stacking

[0086] The lamination and pre-stacking can be done manually by placing the embedded substrate 02 into the corresponding groove, such as... Figure 2 As shown.

[0087] S2. Fabrication of a PCB circuit board containing an air dielectric cavity 05

[0088] S2-1. Use a high-precision CNC cutting machine to cut the copper-clad board to the predetermined size, with the tolerance controlled within ±0.1mm. After cutting, the board is sent to an oven for baking to remove internal stress and prevent warping and deformation during subsequent processing.

[0089] S2-2, Fabricating the inner layer circuitry

[0090] S2-2-1. Thoroughly remove oil and oxide layers from copper surface 08 through chemical cleaning or mechanical brushing, followed by micro-etching treatment to roughen copper surface 08 at the microscopic level and form a uniform roughness. The purpose is to enhance the adhesion between the subsequent dry film and copper surface 08.

[0091] S2-2-2. Apply a layer of photosensitive dry film to the cleaned and roughened copper surface 08 by hot pressing.

[0092] S2-2-3. Place the designed circuit pattern film onto the board surface and irradiate it with ultraviolet light. The light passes through the transparent part of the film, causing the dry film underneath to undergo a photopolymerization reaction and harden.

[0093] S2-2-4. Immerse the exposed board in the developer. The dry film that has not been exposed to ultraviolet light will dissolve and be washed away, exposing the copper foil underneath. The exposed and hardened dry film will remain, covering the copper foil area that will become line 09. At this point, the pattern of line 09 has been completely transferred to the board.

[0094] S2-2-5. After development, the board is sent to the etching machine and sprayed with chemical solution (such as acidic copper chloride). The copper foil not protected by the dry film will be dissolved by the solution, while the copper foil covered by the dry film will be preserved intact.

[0095] S2-2-6. After etching, use a strong alkaline solution to remove the dry film of the protective circuit 09, exposing the clear copper circuit 09.

[0096] S3, OPE punching

[0097] S4, Core board window opening

[0098] To create a window in the core board 06, the core board 06 needs to be made to have a window made at a specified location. The window area will be formed into a cavity after the pressing process. Therefore, the core board 06 to be made to have a window is selected according to the specific location of the cavity required. The tolerance of the window size is ±0.03mm.

[0099] S5. Browning the core board after window opening.

[0100] S6, prepreg for gongs and gongs

[0101] The prepreg 07 needs to have the windowed area cut out in it. The windowed area will form a cavity after the lamination process. Therefore, the prepreg 07 for which the windowing is performed is selected according to the specific location of the cavity required.

[0102] For the prepreg 07 in the milling process, first punch holes to create corresponding fusion positioning holes 01 and rivet holes, then mill grooves are made, using positioning holes 01 for positioning; the milling groove of the prepreg is required to be 0.15mm larger on each side than the embedded substrate 02; when milling the prepreg 07, rough milling + fine milling is used, with a 0.05mm allowance on each side for fine milling, the rough milling cutter is limited to 2m, the fine milling cutter is limited to 5m, and a double-edged milling cutter is used for fine milling at normal feed rate.

[0103] The routing process uses OPE punch holes as positioning holes 01, and the selected holes need to be anti-fool holes 04; the core board window size is required to be 0.1mm larger on each side than the embedded substrate size 02; when routing the core board window, coarse routing + fine routing are used, with a 0.05mm allowance on each side for fine routing. The waste area routing band is designed for routing breakage treatment, the stacking height is controlled ≤3mm, and a cover plate must be added when routing the board.

[0104] S7, Pressing Pre-Lamination and Pressing

[0105] The core boards 06 and prepregs 07 are stacked in a preset order, and an embedded substrate 02 is placed in the window area of ​​the prepreg 07. The embedded substrate 02 can provide pressure support for the window position to ensure that the cavity will not deform during the pressing process.

[0106] The PCB circuit board 05 has a low manufacturing cost because the embedded substrate 02 can be directly supported by the raw material core board 06 and the prepreg 07, so no additional cost is required.

[0107] Finally, it should be noted that the specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. It is obvious to those skilled in the art that this application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this application is defined by the appended claims rather than the foregoing description, and therefore all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within this application.

Claims

1. A PCB circuit board containing an air dielectric cavity, characterized in that, It includes an air dielectric cavity (03) disposed on a PCB circuit board (05), and an embedded groove is provided around the air dielectric cavity (03), and an embedded substrate (02) is installed in the embedded groove; the embedded substrate (02) is made of copper foil laminate etched with copper foil and then laminated with a prepreg (07) or uses embedded copper.

2. The PCB circuit board containing an air dielectric cavity according to claim 1, characterized in that, The embedding groove is provided in multiple ways, and an embedding substrate (02) is installed in each embedding groove.

3. A PCB circuit board with an air dielectric cavity according to claim 1, characterized in that, The distance between the embedded substrate (02) and the air medium cavity (03) is L, where 0.2mm ≤ L ≤ 2mm.

4. A PCB circuit board containing an air dielectric cavity according to claim 1, characterized in that, The inner layer of the embedded substrate (02) is etched with positioning points.

5. A PCB circuit board containing an air dielectric cavity according to claim 1, characterized in that, When the layer containing the air dielectric cavity (03) has electrical isolation requirements, copper plating is performed on it before the embedded substrate (02) is placed in.

6. A PCB circuit board containing an air dielectric cavity according to claim 1, characterized in that, The target thickness of the embedded substrate (02) is determined by the following formula: Embedded substrate thickness = 96% × theoretical board thickness + 0.05 mm; the thickness tolerance requirement is ±0.015 mm.

7. A PCB circuit board with an air dielectric cavity according to claim 1, characterized in that, The tolerance requirements for the length and width of the embedded substrate (02) are ±0.03mm.

8. A PCB circuit board containing an air dielectric cavity according to claim 1, characterized in that, The method for fabricating the embedded substrate (02) includes the following steps: The inner layer of the core board (06) is etched to remove redundant copper foil, then OPE punching is performed, and then a prepreg (07) is selected for lamination. After lamination, drilling is performed. Based on the dimensions of the embedded substrate (02), the grooves are made on the board, and then the pre-stacking is performed to obtain the embedded substrate (02) for embedding in the embedded groove of the PCB circuit board (05).

9. A method for manufacturing a PCB circuit board containing an air dielectric cavity, characterized in that, Includes the following steps: An embedded substrate (02) is fabricated using the fabrication method described in claim 8; On the core board (06) layer of the main PCB material, a window is made corresponding to the preset air dielectric cavity (03) position to form the core board (06) window area; On the prepreg (07) layer of the main PCB material, a window is made corresponding to the window area of ​​the core board (06) to form the window area of ​​the prepreg (07); The embedded substrate (02) is placed into the window area of ​​the prepreg (07) and then pressed. The embedded substrate (02) serves as a rigid support point during the pressing process, so that the window area of ​​the prepreg (07) forms a dimensionally stable air medium cavity (03) after pressing.

10. A method for manufacturing a PCB circuit board containing an air dielectric cavity according to claim 9, characterized in that, The dimensional tolerance requirement for the window area of ​​the core board (06) is ±0.03mm.

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