High-frequency circuit board

Abstract

The application relates to the technical field of circuit boards, in particular to a high-frequency circuit board. The high-frequency circuit board comprises a first circuit board layer, a dielectric layer, a second circuit board layer and a PI reinforcing adhesive block; the second circuit board layer comprises a first copper-clad layer, the first copper-clad layer is provided with a step; the first copper-clad layer is sequentially laminated with the dielectric layer and the first circuit board layer; the dielectric layer is provided with a through slot corresponding to the step, the through slot penetrates through the dielectric layer; and the PI reinforcing adhesive block is bonded to the surface of the first circuit board layer facing the dielectric layer and is located in the through slot. The PI reinforcing adhesive block of the high-frequency circuit board is thin enough to support bonding with the dielectric layer and successful accommodation in the through slot, so that the PI reinforcing adhesive block can effectively fix and protect the step; in addition, the through slot does not need to be processed on the first circuit board, the process step of laser depth control on the first circuit board layer is cancelled, the problem of burning of the base material is avoided, and the controllability of the finished product quality of the high-frequency circuit board is improved.

Description

Technical Field

[0001] This application relates to the field of circuit board technology, and in particular to a high-frequency circuit board and 456. Background Technology

[0002] High-frequency circuit boards are key components used in high-frequency circuits and microwave communications, with electromagnetic frequencies above 1 GHz.

[0003] Currently, to save installation space, high-frequency circuit board products use wire bonding to connect the pins to the inner microstrip lines. To facilitate device mounting, a stepped blind slot, also known as a step, needs to be formed by recessing a portion of the board. This step is currently located on the third layer of the high-frequency circuit board. A through-slot needs to be fabricated on the high-frequency circuit board, running from the first copper layer to the third copper layer, to expose the pads within the third-layer step. To protect the pads within the step, a common solution is to fill the through-slot with Teflon resist.

[0004] However, the thinnest possible thickness for Teflon gaskets is only 0.3mm, while the step depth is 0.35mm. Consequently, the slot depth is also 0.35mm, which is insufficient to effectively secure the Teflon gasket. Furthermore, the substrate dielectric thickness between the first and second copper layers of current high-frequency circuit boards is approximately 0.25mm. When machining slots on this 0.25mm substrate dielectric, laser depth control can easily burn the substrate, making it difficult to control the quality of the finished product. Utility Model Content

[0005] The purpose of this application is to provide a high-frequency circuit board that, to a certain extent, solves the technical problems in the prior art, such as the difficulty in achieving a 0.35mm deep Teflon gasket filling step and the tendency to burn the substrate when using laser depth control to process a through groove that penetrates 0.25mm of substrate dielectric.

[0006] This application provides a high-frequency circuit board, including a first circuit board layer, a dielectric layer, a second circuit board layer, and a PI reinforcing resist block. The second circuit board layer includes a first copper cladding layer, and the first copper cladding layer is provided with steps; The dielectric layer and the first circuit board layer are sequentially laminated on the first copper cladding layer; The medium layer is provided with a through groove corresponding to the step, and the through groove extends through the medium layer; The PI reinforcing adhesive block is bonded to the surface of the first circuit board facing the dielectric layer and is located within the through groove.

[0007] In the above technical solution, the groove wall of the through groove is further offset outward relative to the edge of the step by a first predetermined interval; The first predetermined interval is 1.5-2.5 mil.

[0008] In any of the above technical solutions, the edge of the PI reinforcing adhesive block is further offset inward by a second predetermined interval relative to the edge of the step; The second predetermined interval is 1.5-2.5 mil.

[0009] In any of the above technical solutions, the PI reinforcing resist block further has a single-sided adhesive facing the first circuit board layer, and the PI reinforcing resist is bonded to the first circuit board layer through the single-sided adhesive. The thickness of the PI reinforcing resist block is not less than the thickness of the dielectric layer.

[0010] In any of the above technical solutions, the thickness difference between the PI reinforcing resist block and the dielectric layer is further 0.07-0.1 mm.

[0011] In any of the above technical solutions, further, the thickness of the PI reinforcing resist block is 0.15 mm; wherein, The thickness of the dielectric layer is 0.075 mm, or the thickness of the dielectric layer is 0.056 mm.

[0012] In any of the above technical solutions, the first circuit board layer further includes a first core board and a second copper cladding layer that are laminated together. The first core board is laminated to the first surface of the dielectric layer, and the PI reinforcing resist block is bonded to the surface of the first core board facing the dielectric layer on one side.

[0013] In any of the above technical solutions, the second circuit board layer further includes the first copper clad layer, the second core board, and the third copper clad layer that are laminated together; The first copper clad layer and the third copper clad layer are laminated to the two side surfaces of the second core board, respectively, and the first copper clad layer is laminated to the second surface of the dielectric layer.

[0014] In any of the above technical solutions, further, multiple steps are provided, multiple through slots are provided, and the multiple through slots are arranged opposite to the multiple steps in a one-to-one correspondence; Multiple PI reinforcing adhesive blocks are provided, and each of the multiple PI reinforcing adhesive blocks is disposed in a corresponding manner within a multiple through groove.

[0015] In any of the above technical solutions, the plurality of steps are arranged in multiple rows, the plurality of through grooves are arranged in multiple rows, and the plurality of PI reinforcing adhesive blocks are arranged in multiple rows.

[0016] Compared with the prior art, the beneficial effects of this application are as follows: The high-frequency circuit board provided in this application has a PI reinforcing resist block bonded to the surface of the first circuit board layer facing the dielectric layer and located within the through groove, opposite to the step on the second circuit board. The PI reinforcing resist block can be made very thin, much thinner than the thinnest Teflon thickness of 0.3mm in related technologies. Thus, the PI reinforcing resist block is thin enough to support bonding with the dielectric layer and be successfully accommodated within the through groove. Consequently, the PI reinforcing resist block can be effectively fixed to protect the step. In addition, there is no need to process the through groove on the first circuit board, eliminating the laser depth control process on the first circuit board layer, avoiding the problem of burning the substrate, and improving the controllability of the finished high-frequency circuit board quality. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a high-frequency circuit board in related technologies; Figure 2 This is a schematic diagram of the structure of a high-frequency circuit board provided in an embodiment of this application.

[0019] Figure 1 The attached figure labels are: 71-First substrate; 72-Second dielectric layer; 73-Third substrate; 74-Teflon gasket Figure 2 Figure label: 1-First circuit board layer; 10-Second copper cladding layer; 11-First core board; 2-Dielectric layer; 3-Second circuit board layer; 30-First copper cladding layer; 31-Second core board; 32-Third copper cladding layer; 4-PI reinforcing resist block; 5-Through groove. Detailed Implementation

[0020] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0021] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, 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, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of 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.

[0023] In related technologies, such as Figure 1 As shown, the high-frequency circuit board product includes a first substrate 71, a second dielectric layer 72, and a third substrate 73. The third substrate 73 has a step, within which conductive structures such as copper surfaces or pads are provided for device mounting. A through-slot penetrates the first substrate 71 and the second dielectric layer 72, exposing the step of the third substrate 73. The first substrate 71 has a thickness of 0.254 mm, meaning the substrate thickness between the first and second copper surfaces is 0.254 mm. The second dielectric layer 72 has a thickness of 0.1 mm, resulting in a step depth of 0.354 mm. Since the Teflon gasket 74 can only be made as thin as 0.3 mm, the thickness difference between the step depth and the Teflon gasket 74 is too small, causing the Teflon gasket 74 to be unable to be effectively fixed when filled into the through-slot. Furthermore, when machining the through-slot on the first substrate 71, laser depth control can easily burn the substrate, making it difficult to control the quality of the finished high-frequency circuit board.

[0024] See Figure 2 As shown, this embodiment provides a high-frequency circuit board, including a first circuit board layer 1, a dielectric layer 2, a second circuit board layer 3, and a PI reinforcing resist block 4. The thickness of the first circuit board layer 1 is comparable to the thickness of the first substrate layer in related technologies, the thickness of the dielectric layer 2 is comparable to the thickness of the dielectric layer 2 in related technologies, and the thickness of the second circuit board layer 3 is comparable to the thickness of the third substrate layer in related technologies.

[0025] The second circuit board layer 3 includes a first copper cladding layer 30, which has steps and copper surfaces or pads within the steps for device mounting.

[0026] A dielectric layer 2 and a first circuit board layer 1 are sequentially laminated on the first copper cladding layer 30. The dielectric constant of the dielectric layer 2 can be, for example, 3.0 or less, and the dielectric layer 2 is, for example, a PP layer. The dielectric layer 2 is provided with a through slot 5 corresponding to the step. The through slot 5 penetrates the dielectric layer 2 so that the step can be exposed through the through slot 5.

[0027] The PI reinforcing resist block 4 is bonded to the surface of the first circuit board layer 1 facing the dielectric layer 2 and is located within the through groove 5. The PI reinforcing resist block 4 can be made very thin, specifically, much thinner than 0.3 mm, such as 0.1 mm or 0.15 mm, and has high temperature resistance properties, allowing for hot pressing. Thus, the PI reinforcing resist block 4 is thin enough to support bonding with the dielectric layer 2 and be successfully accommodated within the through groove 5. This effectively fixes the PI reinforcing resist block 4 to protect the steps. Furthermore, there is no need to process the through groove 5 on the first circuit board layer 1, eliminating the laser depth control process on the first circuit board, avoiding the problem of substrate burning, and improving the controllability of the high-frequency circuit board finished product quality.

[0028] In the optional scheme of this embodiment, multiple steps are provided, multiple through grooves 5 are provided, and multiple through grooves 5 are provided in a one-to-one correspondence with multiple steps; multiple PI reinforcing adhesive blocks 4 are provided, and multiple PI reinforcing adhesive blocks 4 are provided in a one-to-one correspondence within multiple through grooves 5.

[0029] It is understandable that the number of through slots 5 and the number of PI reinforcing adhesive blocks 4 are determined by the number of steps. Correspondingly, the position of through slots 5 and the position of PI reinforcing adhesive blocks 4 are also determined by the position of steps.

[0030] In this embodiment, multiple steps are arranged in multiple rows, multiple through slots 5 are arranged in multiple rows, and multiple PI reinforcing adhesive blocks 4 are arranged in multiple rows. Thus, the PI reinforcing adhesive block 4 in each row can be obtained by laser cutting from the same long strip of PI reinforcing adhesive tape bonded to the dielectric layer 2. The bonding position of the PI reinforcing adhesive tape is determined by the position of the steps in the corresponding row, thereby improving the bonding efficiency between the PI reinforcing adhesive block 4 and the dielectric layer 2.

[0031] In an optional embodiment, the wall of the through groove 5 is offset outward from the edge of the step by a first predetermined interval, which is 1.5-2.5 mil. Specifically, it can be 1.5 mil, 2 mil, or 2.5 mil. That is, the single-sided dimension of the through groove 5 is 1.5-2.5 mil larger than the single-sided dimension of the step, to prevent the step from exceeding the range of the through groove 5, so that the step can be fully exposed through the through groove 5.

[0032] In an optional embodiment, the edge of the PI reinforcing adhesive block 4 is offset inward relative to the edge of the step by a second predetermined interval, which is 1.5-2.5 mil. Specifically, it can be 1.5 mil, 2 mil, or 2.5 mil. That is, the single-sided dimension of the PI reinforcing adhesive block 4 is 1.5-2.5 mil smaller than the single-sided dimension of the step, to prevent the PI reinforcing adhesive block 4 from exceeding the step range.

[0033] It is understood that the cross-sectional shapes of the step, the through groove 5, and the PI reinforcing adhesive block 4 are contour-following designs, and can be regular or irregular shapes, without limitation. Optionally, the cross-sectional shapes of the step, the through groove 5, and the PI reinforcing adhesive block 4 are all rectangular; or, the cross-sectional shapes of the step, the through groove 5, and the PI reinforcing adhesive block 4 are all circular.

[0034] In an optional embodiment, the PI reinforcing resist block 4 has a single-sided adhesive backing facing the first circuit board layer 1, and the PI reinforcing resist block 4 is bonded to the first circuit board layer 1 through the single-sided adhesive backing. Specifically, using PI reinforcing resist tape with self-adhesive backing facilitates the application of multiple PI reinforcing resist tapes to the dielectric layer 2 on the entire board surface. After application, it is easy to perform uniform cold pressing and laser cutting, thereby obtaining multiple PI reinforcing resist blocks 4 bonded to the dielectric layer 2.

[0035] The thickness of the PI reinforcing resist block 4 is not less than the thickness of the dielectric layer 2, so that the PI reinforcing resist block 4 can extend into the step to protect the conductive structures such as the copper surface or solder pads therein.

[0036] In the optional scheme of this embodiment, the thickness difference between the PI reinforcing resist block 4 and the dielectric layer 2 is 0.07-0.1mm. Specifically, it can be 0.07mm, 0.08mm or 0.1mm. Depending on the thickness of the dielectric layer 2 and the thickness requirements of the PI reinforcing resist block 4, the materials used can be selected comprehensively to meet the thickness difference requirements and ensure that they can adapt to the step depth.

[0037] In a specific example, the thickness of the PI reinforcing adhesive block 4 is 0.15 mm, and correspondingly, the thickness of the dielectric layer 2 is 0.075 mm, or the thickness of the dielectric layer 2 is 0.056 mm. The thickness of the PI reinforcing adhesive block 4 is 0.15 mm, which is significantly less than the 0.3 mm thickness of the Teflon gasket used in related technologies, thus supporting adhesive bonding.

[0038] In an optional embodiment, the first circuit board layer 1 includes a first core board 11 and a second copper-clad layer 10 bonded together. The first core board 11 is laminated to the first surface of the dielectric layer 2. The PI reinforcing resist block 4 is bonded to the surface of the first core board 11 facing the dielectric layer 2 on one side, that is, the second copper-clad layer 10 is pressed onto the side of the first core board 11 facing away from the dielectric layer 2. When it is necessary to mount devices onto the step, the first circuit board needs to be peeled off to expose the step.

[0039] In an optional embodiment, the second circuit board layer 3 includes a first copper clad layer 30, a second core board 31, and a third copper clad layer 32 that are laminated together.

[0040] The first copper clad layer 30 and the third copper clad layer 32 are laminated to the two side surfaces of the second core board 31, respectively. The first copper clad layer 30 is laminated to the second surface of the dielectric layer 2. That is, the third copper clad layer 32 is laminated to the side of the second core board 31 away from the dielectric layer 2.

[0041] Specifically, in manufacturing this high-frequency circuit board, multiple strips of PI reinforcing resist tape are applied to the entire surface of the first core board 11 of the first circuit board. After application, two cold-pressing rollers are used, and finally, laser cutting is performed to obtain multiple PI reinforcing resist blocks 4 corresponding to multiple steps. Multiple through slots 5 are processed on the dielectric layer 2. The dielectric layer 2 is only about 0.1mm thick. The through slots 5 are simple and easy to process, and there is no need for laser depth control on the first circuit board, which can avoid the problem of burning the substrate. Then, the first circuit board, dielectric layer 2, and second circuit board are stacked. The first copper clad layer 30 of the second circuit board is opposite to the second surface of the dielectric layer 2. The multiple through slots 5 correspond one-to-one with the multiple steps. The first core board 11 of the first circuit board is opposite to the first surface of the dielectric layer 2. The PI reinforcing resist blocks 4 are correspondingly placed in the through slots 5. Then, hot pressing is performed. After hot pressing, the two sides of the dielectric layer 2 are pressed against the first core board 11 and the first copper clad layer 30, respectively. When mounting components onto the step, the first circuit board needs to be peeled off. After peeling off, the step is exposed, and the required components can be mounted or soldered onto the copper surface or pads inside the step. Some excess adhesive may accumulate inside the step. This excess adhesive can be effectively removed using methods such as plasma adhesive removal, desoldering, and sandblasting, or a combination of manual repair, micro-etching, and sandblasting, or UV laser removal of residual adhesive. All these methods do not affect the reliability of the high-frequency circuit board.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model. In addition, those skilled in the art can understand that although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments means that they are within the scope of this utility model and form different embodiments. For example, any one of the claimed embodiments can be used in any combination. The information disclosed in this background section is only intended to deepen the understanding of the overall background technology of this utility model, and should not be regarded as an admission or in any form implying that the information constitutes prior art known to those skilled in the art.

Claims

1. A high-frequency circuit board, characterized in that, It includes a first circuit board layer, a dielectric layer, a second circuit board layer, and a PI reinforcing resist block; The second circuit board layer includes a first copper cladding layer, and the first copper cladding layer is provided with steps; The dielectric layer and the first circuit board layer are sequentially laminated on the first copper cladding layer; The medium layer is provided with a through groove corresponding to the step, and the through groove extends through the medium layer; The PI reinforcing adhesive block is bonded to the surface of the first circuit board facing the dielectric layer and is located within the through groove.

2. The high-frequency circuit board according to claim 1, characterized in that, The wall of the through groove is offset outward relative to the edge of the step by a first predetermined interval; The first predetermined interval is 1.5-2.5 mil.

3. The high-frequency circuit board according to claim 1, characterized in that, The edge of the PI reinforcing adhesive block is offset inward at a second predetermined interval relative to the edge of the step; The second predetermined interval is 1.5-2.5 mil.

4. The high-frequency circuit board according to claim 1, characterized in that, The PI reinforcing adhesive block has a single-sided adhesive facing the first circuit board layer, and the PI reinforcing adhesive is bonded to the first circuit board layer through the single-sided adhesive. The thickness of the PI reinforcing resist block is not less than the thickness of the dielectric layer.

5. The high-frequency circuit board according to claim 4, characterized in that, The thickness difference between the PI reinforcing resist block and the dielectric layer is 0.07-0.1 mm.

6. The high-frequency circuit board according to claim 5, characterized in that, The thickness of the PI reinforcing adhesive block is 0.15 mm; wherein, The thickness of the dielectric layer is 0.075 mm, or the thickness of the dielectric layer is 0.056 mm.

7. The high-frequency circuit board according to claim 1, characterized in that, The first circuit board layer includes a first core board and a second copper clad layer that are laminated together. The first core board is laminated to the first surface of the dielectric layer, and the PI reinforcing resist block is bonded to the surface of the first core board facing the dielectric layer on one side.

8. The high-frequency circuit board according to claim 7, characterized in that, The second circuit board layer includes a first copper clad layer, a second core board, and a third copper clad layer that are laminated together; The first copper clad layer and the third copper clad layer are laminated to both sides of the second core board, and the first copper clad layer is laminated to the second surface of the dielectric layer.

9. The high-frequency circuit board according to claim 1, characterized in that, The steps are provided in multiple ways, and the through slots are provided in multiple ways, with each of the through slots corresponding to one of the steps. Multiple PI reinforcing adhesive blocks are provided, and each of the multiple PI reinforcing adhesive blocks is disposed in a corresponding manner within a multiple through groove.

10. The high-frequency circuit board according to claim 9, characterized in that, The multiple steps are arranged in multiple rows, the multiple through grooves are arranged in multiple rows, and the multiple PI reinforcing adhesive blocks are arranged in multiple rows.

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