A method for preparing blind grooves in PTFE high-frequency circuit boards

Abstract

The present invention discloses a method for preparing a blind groove in a PTFE high-frequency circuit board, comprising the following steps: S1: pre-treating an FPTE sheet, an FR4 sheet and an auxiliary core board; S2: attaching a PI protective tape to the bottom of the auxiliary core board; S3: stacking the FR4 sheet, the auxiliary core board and the FPTE sheet in sequence, wherein a first semi-cured sheet is placed between the FR4 sheet and the auxiliary core board, a second semi-cured sheet is placed between the auxiliary core board and the FPTE sheet, and the second semi-cured sheet is filled on the side of the PI protective tape; S4: pressing the stacked sheets to form a pressed plate; S5: drilling a hole in the pressed plate above the PI protective tape to form a blind groove located at the top of the PTFE. The present invention provides a method for preparing a blind groove in a PTFE high-frequency circuit board, which does not affect the performance of the PTFE sheet when drilling to form the blind groove, thereby improving the qualified rate of the PTFE high-frequency circuit board.

Description

Technical Field

[0001] The invention relates to the field of PTFE high-frequency circuit board preparation, in particular to a method for preparing a blind groove in a PTFE high-frequency circuit board. Background Art

[0002] With the rapid development of high-end automobiles, communications, signal transmission and other electronic products, the demand for various circuit boards for high-frequency signal transmission is increasing day by day. PTFE (polytetrafluoroethylene) material has a low dielectric constant and dielectric loss, and excellent electrical properties. It has excellent chemical stability and is widely used in products such as radar, communications, and microwave devices. However, PTFE is a thermoplastic material with poor rigidity, easy deformation, and poor adhesion, which requires special control over PCB processing. Especially in high-frequency circuit boards, the thickness of PTFE sheets is relatively small, even as small as about 5 mil. For PTFE sheets of this size, both the lamination and blind groove processes will affect their performance, resulting in the breakage of the PTFE sheets and the scrapping of high-frequency circuit boards. Summary of the invention

[0003] The present invention aims to solve at least one of the problems in the related art to a certain extent. To this end, the purpose of the present invention is to provide a method for preparing a blind groove in a PTFE high-frequency circuit board, which will not affect the performance of the PTFE sheet when drilling to form the blind groove, thereby improving the qualified rate of the PTFE high-frequency circuit board.

[0004] In order to achieve the above-mentioned purpose, the present application adopts the following technical solution: a method for preparing a blind groove in a PTFE high-frequency circuit board, comprising the following steps:

[0005] S1: Pre-treat PTFE sheet, FR4 sheet and auxiliary core sheet;

[0006] S2: Stick PI protective tape on the bottom of the auxiliary core board;

[0007] S3: stacking the FR4 sheet, the auxiliary core sheet and the PTFE sheet in sequence, wherein a first prepreg is placed between the FR4 sheet and the auxiliary core sheet, a second prepreg is placed between the auxiliary core sheet and the PTFE sheet, and the second prepreg is filled on the side of the PI protective tape;

[0008] S4: Pressing the stacked plates to form a pressed plate;

[0009] S5: Drill holes in the laminate above the PI protective tape to form a blind groove that sits on top of the PTFE.

[0010] Furthermore, in step S2, the inner side of the PI protective tape is pasted on the bottom of the auxiliary core board; the outer side of the PI protective tape is laser cut so that the height of the PI protective tape is the same as the height of the second semi-cured sheet; wherein the inner side of the PI protective tape is coated with glue, and the outer side is not coated with glue.

[0011] Furthermore, in step S1, a bottom inner layer circuit is deposited on the surface of the PTFE sheet, and the height of the bottom inner layer circuit is smaller than the height of the second prepreg.

[0012] Furthermore, in step S2, the inner side of the PI protective tape is pasted on the bottom of the auxiliary core board, and the outer side of the PI protective tape is laser cut so that the height of the PI protective tape is the same as the height of the second semi-cured sheet, the width of the PI protective tape is greater than the width of the bottom inner layer circuit, and the outer side of the PI protective tape forms a groove that matches the bottom inner layer circuit; wherein, the inner side of the PI protective tape is coated with glue, and the outer side is not coated with glue.

[0013] Furthermore, the distance between the edge of the PI protective tape and the edge of the bottom inner layer circuit is 7-9 mil.

[0014] Furthermore, before the lamination in step S4, an auxiliary film is placed on the top of the FR4 sheet and the bottom of the PTFE sheet, and the hardness of the auxiliary film is less than that of the PTFE sheet and the FR4 sheet.

[0015] Furthermore, the auxiliary film is a three-in-one release film.

[0016] Furthermore, when drilling in step S5, the drill stops at the PI protective tape above the PTFE sheet.

[0017] Furthermore, the method further comprises step S6: depositing an outer layer circuit on the bottom of the PTFE sheet and / or the top of the FR4 sheet.

[0018] Furthermore, the thickness of the PTFE sheet is greater than or equal to 5 mil.

[0019] The above-mentioned technical scheme provided by the embodiment of the present application has the following advantages compared with the prior art: the present application sticks the PI protective tape in the auxiliary core board, and fills the second semi-cured sheet on the side of the PI protective tape, so that during the lamination process, the PI protective tape can protect the blind groove area in the PTFE sheet, and during subsequent drilling, the drill only needs to drill through the auxiliary core board, and the PI protective tape will fall off together with the auxiliary core board, so that when drilling the blind groove, the drill keeps a distance from the PTFE sheet to the height of the PI protective tape, ensuring that the drilling process will not affect the PTFE sheet, thereby improving the qualified rate of the PTFE high-frequency circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] In the attached figure:

[0023] Figure 1 This is a schematic diagram of the stacking of plates in Example 2 of the present application;

[0024] Figure 2 This is a schematic diagram of drilling holes when a blind groove is formed on a plate in Example 2 of the present application;

[0025] Figure 3 This is a schematic diagram of forming a blind groove including a bottom inner layer circuit in Example 2 of the present application;

[0026] Figure numbers: 1, outer layer circuit; 2, FR4 board; 3, top inner layer circuit; 4, first prepreg; 5, auxiliary core board; 6, PI protective tape; 7, second prepreg; 8, bottom inner layer circuit; 9, PTFE board. DETAILED DESCRIPTION

[0027] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings, are constructed and operated in a specific direction, and are only for the convenience of describing the present technical solution, rather than indicating that the mechanism or element referred to must have a specific direction, and therefore cannot be understood as a limitation to the present invention.

[0028] It should also be noted that, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intermediate elements. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", "third", etc. can explicitly or implicitly include one or more of the features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0029] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, mechanisms, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0030] The present application provides a method for preparing a blind groove in a PTFE high-frequency circuit board, comprising the following steps:

[0031] S1: pre-treating the PTFE sheet 9, the FR4 sheet 2 and the auxiliary core sheet 5;

[0032] S2: Paste PI protective tape 6 on the bottom of the auxiliary core board 5;

[0033] S3: stacking the FR4 sheet 2, the auxiliary core plate 5 and the PTFE sheet 9 in sequence, wherein the first prepreg 4 is placed between the FR4 sheet 2 and the auxiliary core plate 5, the second prepreg 7 is placed between the auxiliary core plate 5 and the PTFE sheet 9, and the second prepreg 7 is filled on the side of the PI protective tape 6;

[0034] S4: Pressing the stacked plates to form a pressed plate;

[0035] S5: Drill a hole in the laminate above the PI protective tape 6 to form a blind groove located on top of the PTFE.

[0036] In the present application, the PI protective tape 6 is pasted in the auxiliary core board 5, and the second semi-cured sheet 7 is filled on the side of the PI protective tape 6, so that during the lamination process, the PI protective tape 6 can protect the blind groove area in the PTFE sheet, and during the subsequent drilling, the drill only needs to drill through the auxiliary core board 5, and the PI protective tape 6 will fall off together with the auxiliary core board 5, so that when drilling the blind groove, the drill keeps a height distance of the PI protective tape 6 from the PTFE sheet, ensuring that the drilling process will not affect the PTFE sheet, thereby improving the qualified rate of the PTFE high-frequency circuit board.

[0037] Example 1

[0038] The present application provides a method for preparing a blind groove in a PTFE high-frequency circuit board, comprising the following steps:

[0039] S1: pre-treat the PTFE sheet 9, the FR4 sheet 2 and the auxiliary core plate 5. And define a blind groove area in the auxiliary core plate 5.

[0040] In the present application, the thickness of the PTFE sheet 9 is greater than or equal to 5 mil, that is, the minimum thickness of the PTFE substrate can be 5 mil.

[0041] S2: Attach the PI protective tape 6 to the bottom of the auxiliary core board 5; the inner side of the PI protective tape 6 is coated with glue, and the outer side is not coated with glue; that is, only one side of the PI protective tape 6 has glue.

[0042] Specifically, it includes: sticking the inner side of the PI protective tape 6 to the bottom of the auxiliary core board 5, and using laser cutting to cut the outer side of the PI protective tape 6 so that the height of the PI protective tape 6 is the same as the height of the second semi-cured sheet 7, and the width and position of the PI protective tape 6 are consistent with the blind groove interval defined in step S1.

[0043] When using laser to cut PI protective tape 6, the energy needs to be adjusted according to the thickness of PI protective tape 6. The laser energy needs to be controlled within 2-15mj. Avoid excessive energy that will burn the auxiliary core board 5, causing the product to be short of glue and cause related defects. Do not set the energy too small, otherwise the PI protective tape 6 will not be burned through and cannot be torn off. After laser cutting, the carbon powder needs to be wiped with alcohol to prevent problems such as product short circuit. After completing the above process, a vacuum fast press needs to be used for fast pressing to increase the bonding strength between the PI protective tape 6 and the auxiliary core board 5.

[0044] S3: Stack the FR4 sheet 2, the auxiliary core board 5 and the PTFE sheet 9 in sequence, wherein a first semi-cured sheet 4 is placed between the FR4 sheet 2 and the auxiliary core board 5, a second semi-cured sheet 7 is placed between the auxiliary core board 5 and the PTFE sheet 9, and the second semi-cured sheet 7 is filled on the side of the PI protective tape 6.

[0045] The second semi-cured sheet 7 is wrapped around the side of the PI protective tape 6, that is, the height of the second semi-cured sheet 7 is equal to the height of the PI protective tape 6. In practical applications, the second semi-cured sheet 7 needs to be punched according to the position and shape of the PI protective tape 6 to ensure that the second semi-cured sheet 7 can be adapted to the shape of the PI protective tape 6 when filled between the auxiliary core plate 5 and the PTFE sheet 9. The PI protective tape 6 is placed in the bottom inner layer circuit 8 after the semi-cured sheet is melted at high temperature to play a role in blocking glue.

[0046] S4: Pressing the stacked plates to form a pressed plate.

[0047] An auxiliary film is placed on the top of the FR4 sheet 2 and the bottom of the PTFE sheet 9, and the hardness of the auxiliary film is less than that of the PTFE sheet 9 and the FR4 sheet 2; the auxiliary film can be a three-in-one release film. The upper and lower layers of the three-in-one release film use high-temperature release films, and the middle layer is a composite buffer film; it has the characteristics of high temperature resistance, good filling and coating, and good release effect. The upper and lower release layers of the three-in-one release film play the role of isolating the production board at high temperature, and the middle buffer film plays an effective filling and punching role, which effectively compresses the multi-layer board, the soft-hard combination board and the circuit board with a large height difference to prevent defects such as delamination and blistering.

[0048] Since the hardness of the PTFE sheet 9 and the FR4 sheet 2 is relatively low, during the pressing process, due to the existence of the top inner layer circuit 3 and the bottom inner layer circuit 8, the pressing force at various locations of the PTFE sheet 9 and the FR4 sheet 2 is uneven, which can easily cause wrinkles on the PTFE sheet 9 and the FR4 sheet 2, resulting in the scrapping of the circuit board. The present application ensures that the pressing force at various locations of the PTFE sheet 9 and the FR4 sheet 2 is equal by placing auxiliary plates at the top and bottom of the circuit board, thereby improving the pressing uniformity of the circuit board.

[0049] S5: Drill a hole in the laminate above the PI protective tape 6 to form a blind groove located on top of the PTFE.

[0050] Since the blind groove interval has been defined in step S1, when drilling to form the blind groove, it is only necessary to drill in the vertical direction of the PI protective tape 6. During blind fishing, the drill stops at the PI protective tape 6 above the PTFE sheet 9, that is, the PI protective tape 6 cannot be drilled through. Preferably, it is only necessary to drill through the blind groove interval defined in the auxiliary core board 5. Since there is no glue on the outside of the PI protective tape 6, when the auxiliary core board 5 is drilled through, the auxiliary line board can drive the PI protective tape 6 to be taken out, thereby ensuring that a distance can be maintained between the drill and the PTFE sheet 9, and there is no need to worry about the low hardness of the PTFE sheet 9 being affected by the drill, thereby improving the qualified rate of the PTFE high-frequency circuit board.

[0051] S6: Deposit the outer circuit 1 on the bottom of the PTFE sheet 9 and / or the top of the FR4 sheet 2. The position and shape of the outer circuit 1 can be deposited according to the requirements of the circuit board.

[0052] Example 2

[0053] like Figure 1-Figure 3 As shown, the present application provides a method for preparing a blind groove in a PTFE high-frequency circuit board, comprising the following steps:

[0054] S1: pre-treating the PTFE sheet 9, the FR4 sheet 2 and the auxiliary core sheet 5.

[0055] Among them, the pretreatment of the PTFE sheet 9, the auxiliary core plate 5, and the FR4 sheet 2 includes cutting and depositing inner layer circuits; the specific deposition of the inner layer circuits includes depositing the bottom internal circuits on the top of the PTFE sheet 9, depositing the top inner layer circuits 3 on the bottom of the FR4 sheet 2, and depositing the middle inner layer circuits on both sides of the auxiliary core plate 5. The top and bottom here refer to the order of the sheets from top to bottom, which are FR4 sheet 2, auxiliary core plate 5, and PTFE sheet 9. The top of the PTFE sheet 9 is the side close to the auxiliary core plate 5, and the bottom of the FR4 sheet 2 is the side close to the auxiliary core plate 5. In this application, the order of the sheets from top to bottom is FR4 sheet 2, auxiliary core plate 5, and PTFE sheet 9 as an example for explanation, and the top and bottom mentioned are all indicated in terms of orientation based on this stacking order.

[0056] It should be noted that the specific position and shape of the inner layer circuit and whether deposition is required are determined according to the actual needs of the circuit board.

[0057] In the present application, the thickness of the PTFE sheet 9 is greater than or equal to 5 mil, that is, the minimum thickness of the PTFE substrate can be 5 mil.

[0058] S2: Attach the PI protective tape 6 to the bottom of the auxiliary core board 5; the inner side of the PI protective tape 6 is coated with glue, and the outer side is not coated with glue; that is, only one side of the PI protective tape 6 has glue.

[0059] Specifically, it includes: sticking the inner side of the PI protective tape 6 to the bottom of the auxiliary core board 5, using laser cutting on the outer side of the PI protective tape 6, so that the height of the PI protective tape 6 is the same as the height of the second semi-cured sheet 7, the width of the PI protective tape 6 is greater than the width of the bottom inner layer circuit 8, and the outer side of the PI protective tape 6 forms a groove that matches the bottom inner layer circuit 8, which is used to wrap the bottom inner layer circuit 8. Specifically, the distance between the edge of the PI protective tape 6 and the edge of the bottom inner layer circuit 8 is 7-9mil, and preferably, the PI protective tape 6 is 8mil larger than the bottom inner layer circuit 8 on one side.

[0060] When using laser to cut PI protective tape 6, the energy needs to be adjusted according to the thickness of PI protective tape 6. The laser energy needs to be controlled within 2-15mj. Avoid excessive energy that will burn the auxiliary core board 5, causing the product to be short of glue and cause related defects. Do not set the energy too small, otherwise the PI protective tape 6 will not be burned through and cannot be torn off. After laser cutting, the carbon powder needs to be wiped with alcohol to prevent problems such as product short circuit. After completing the above process, a vacuum fast press needs to be used for fast pressing to increase the bonding strength between the PI protective tape 6 and the auxiliary core board 5.

[0061] S3: Stack the FR4 sheet 2, the auxiliary core board 5 and the PTFE sheet 9 in sequence, wherein a first semi-cured sheet 4 is placed between the FR4 sheet 2 and the auxiliary core board 5, a second semi-cured sheet 7 is placed between the auxiliary core board 5 and the PTFE sheet 9, and the second semi-cured sheet 7 is filled on the side of the PI protective tape 6.

[0062] When the top inner layer circuit 3 is deposited on the bottom of the FR4 board 2, the first prepreg 4 wraps the top inner layer circuit 3, that is, the height of the first prepreg 4 is greater than the height of the top inner layer circuit 3. In practical applications, the first prepreg needs to be punched according to the position and shape of the top inner layer circuit 3 to ensure that the first prepreg 4 can be adapted to the shape of the inner layer circuit when filled between the FR4 board 2 and the auxiliary core board 5.

[0063] The second prepreg 7 is wrapped around the side of the PI protective tape 6 , that is, the height of the second prepreg 7 is equal to the height of the PI protective tape 6 .

[0064] In practical applications, the second prepreg 7 needs to be punched according to the position and shape of the PI protective tape 6 to ensure that the second prepreg 7 can be matched with the shape of the PI protective tape 6 when filled between the auxiliary core plate 5 and the PTFE plate 9. The PI protective tape 6 places the prepreg melted at high temperature into the bottom inner layer circuit 8 to play a role in blocking glue.

[0065] S4: Pressing the stacked plates to form a pressed plate.

[0066] An auxiliary film is placed on the top of the FR4 sheet 2 and the bottom of the PTFE sheet 9, and the hardness of the auxiliary film is less than that of the PTFE sheet 9 and the FR4 sheet 2; the auxiliary film can be a three-in-one release film. The upper and lower layers of the three-in-one release film use high-temperature release films, and the middle layer is a composite buffer film; it has the characteristics of high temperature resistance, good filling and coating, and good release effect, and is widely used in circuit boards with high filling and coating requirements. The upper and lower release layers of the three-in-one release film play the role of isolating the production board at high temperature, and the middle buffer film plays an effective filling and punching role, which effectively compresses multi-layer boards, hard-soft boards, and circuit boards with large height differences to prevent defects such as delamination and blistering.

[0067] Since the hardness of the PTFE sheet 9 and the FR4 sheet 2 is relatively low, during the pressing process, due to the existence of the top inner layer circuit 3 and the bottom inner layer circuit 8, the pressing force at various locations of the PTFE sheet 9 and the FR4 sheet 2 is uneven, which can easily cause wrinkles on the PTFE sheet 9 and the FR4 sheet 2, resulting in the scrapping of the circuit board. The present application ensures that the pressing force at various locations of the PTFE sheet 9 and the FR4 sheet 2 is equal by placing auxiliary plates at the top and bottom of the circuit board, thereby improving the pressing uniformity of the circuit board.

[0068] S5: Drill a hole in the laminate above the PI protective tape 6 to form a blind groove located on top of the PTFE.

[0069] like Figure 2 and 3 As shown, the position of the blind groove in the present application is around the bottom inner layer circuit 8, that is, drilling is performed on the outside of the bottom inner layer circuit 8. During blind fishing, the drill stops at the PI protective tape 6 above the PTFE sheet 9, that is, the PI protective tape 6 cannot be drilled through. Since there is no glue on the outside of the PI protective tape 6, when the auxiliary core board 5 is drilled through, the auxiliary line board can drive the PI protective tape 6 to be taken out, thereby ensuring that a distance can be maintained between the drill and the PTFE sheet 9, and there is no need to worry about the PTFE sheet 9 being affected by the drill due to its low hardness, thereby improving the qualified rate of the PTFE high-frequency circuit board.

[0070] It is worth noting that PTFE is a thermoplastic material with poor rigidity, easy deformation, and poor adhesion. Mechanical grinding is prohibited during circuit board processing. The grinding plate needs to be manually polished with chemical micro-etching or sandpaper with a mesh size of 1500 or above. Burrs are likely to remain before blind gong and molding. The path needs to be reduced to the minimum distance. If the molding path overlaps with the blind gong path, the overlapping position needs to be milled out in advance, and the molding will no longer follow this path to prevent the PTFE material from being milled and leaving burrs.

[0071] S6: Deposit the outer circuit 1 on the bottom of the PTFE sheet 9 and / or the top of the FR4 sheet 2. The position and shape of the outer circuit 1 can be deposited according to the requirements of the circuit board.

[0072] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A method for preparing a blind slot in a PTFE high-frequency circuit board, characterized in that: The steps include: S1: Pre-treat PTFE sheet, FR4 sheet and auxiliary core sheet; S2: Stick PI protective tape on the bottom of the auxiliary core board; S3: stacking the PTFE sheet, the auxiliary core plate and the FR4 sheet in sequence from bottom to top, wherein a first prepreg is placed between the FR4 sheet and the auxiliary core plate, a second prepreg is placed between the auxiliary core plate and the PTFE sheet, and the second prepreg is filled on the side of the PI protective tape; S4: placing an auxiliary film on the top of the FR4 sheet and on the bottom of the PTFE sheet, wherein the hardness of the auxiliary film is less than that of the PTFE sheet and the FR4 sheet; and pressing the stacked sheets to form a pressed sheet; S5: Drill holes in the laminate above the PI protective tape to form a blind groove located on top of the PTFE; In step S2, the inner side of the PI protective tape is pasted on the bottom of the auxiliary core board; the outer side of the PI protective tape is laser cut so that the height of the PI protective tape is the same as the height of the second semi-cured sheet; and the inner side of the PI protective tape is coated with glue, while the outer side is not coated with glue.

2. The method for preparing a blind slot in a PTFE high-frequency circuit board according to claim 1, characterized in that: In step S1, a bottom inner layer circuit is deposited on the surface of the PTFE sheet, and the height of the bottom inner layer circuit is less than the height of the second semi-cured sheet; the width of the PI protective tape is greater than the width of the bottom inner layer circuit, and a groove matching the bottom inner layer circuit is formed on the outer side of the PI protective tape.

3. The method for preparing a blind slot in a PTFE high-frequency circuit board according to claim 1, characterized in that: The distance between the edge of the PI protective tape and the edge of the bottom inner layer circuit is 7-9 mil.

4. The method for preparing a blind slot in a PTFE high-frequency circuit board according to claim 1, characterized in that: The auxiliary film is a three-in-one release film.

5. The method for preparing a blind slot in a PTFE high-frequency circuit board according to claim 1, characterized in that: The method further comprises step S6: depositing an outer layer circuit on the bottom of the PTFE sheet and / or the top of the FR4 sheet.

6. The method for preparing a blind slot in a PTFE high-frequency circuit board according to claim 1, characterized in that: The thickness of PTFE sheet is greater than or equal to 5 mil.

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