Method for double-sided back drilling of PTFE (Polytetrafluoroethylene) plate

Abstract

The invention discloses a PTFE plate double-face back drilling method which comprises the steps that S1, a PTFE plate is taken, and a plurality of through holes are machined in preset positions; s2, a first back drilling large hole is machined in the CS face of the PTFE plate; s3, a plurality of pre-drilled holes are machined in the SS face of the PTFE plate, the pre-drilled holes and the through holes are coaxially arranged, and the aperture size of the pre-drilled holes is larger than that of the through holes; s4, a second back-drilled large hole is formed in the SS face of the PTFE plate, after pre-drilling, the second back-drilled large hole is formed in the SS face, at the moment, the drill bit reduces the feeding speed of the drill bit, and therefore the impact force of the drill bit to a residual thick layer is reduced, and the residual thick layer is prevented from being damaged when it is guaranteed that an inner-layer base material and an inner-layer copper foil of the PTFE plate are straight under the condition that the size of the back-drilled large hole is within a certain range. And the thickness of the residual thick layer is smaller, so that the design requirement is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of processing PTFE plate, in particular to a method for double back drilling of PTFE plate. BACKGROUND

[0002] The main purpose of drilling PTFE plate is to realize electrical connection, mechanical fixation and signal transmission.

[0003] At present, PTFE plate is drilled in the form of double back drilling. In the past, the back drilling hole of the CS surface of the PTFE plate was processed first, and then the back drilling hole of the SS surface was drilled. When drilling the back drilling hole of the SS surface, the back drilling hole of the CS surface has been drilled, the hole corresponding to the CS surface at the bottom of the back drilling hole of the SS surface has been processed, and the copper column in the SS surface hole will be impacted by the drill towards the CS surface. The inner layer substrate and the inner layer copper foil are at risk of bending towards the CS surface. When the residual thickness layer is smaller or the size of the back drilling large hole is larger, the inner layer substrate and the inner layer copper foil of the PTFE plate are more prone to deformation. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a method for double back drilling of PTFE plate, which can ensure that the thickness of the residual thickness layer is smaller when the inner layer substrate and the inner layer copper foil of the PTFE plate are flat within a certain range of the size of the back drilling large hole, so as to meet the design requirements.

[0005] According to the method for double back drilling of PTFE plate according to the embodiment of the present application, the method comprises the following steps: S1: taking a piece of PTFE plate and processing a plurality of through holes at predetermined positions; S2: processing a first back drilling large hole on the CS surface of the PTFE plate; S3: processing a plurality of pre-drilling holes on the SS surface of the PTFE plate, the pre-drilling holes are coaxially arranged with the through holes, and the hole diameter size of the pre-drilling holes is larger than the hole diameter size of the through holes; S4: processing a second back drilling large hole on the SS surface of the PTFE plate.

[0006] At least has the following beneficial effects: processing the through hole in the predetermined position, firstly to ensure the accuracy, and then processing other holes, taking the through hole as the positioning reference for processing, processing the first back drilling large hole on the CS surface of the PTFE plate, processing the first back drilling large hole to the predetermined depth, processing a plurality of pre-drilling holes on the SS surface of the PTFE plate, the number of pre-drilling holes is equal to and corresponds to the number of through holes, when processing the second back drilling large hole, the pre-drilling hole has cut part of the material, so that the processing of the second back drilling large hole becomes easier, thereby reducing the processing difficulty of the second back drilling large hole, and when processing, the impact force of the copper column in the SS surface hole drilled downward by the drill will be smaller, thereby realizing that when the inner layer base material and the inner layer copper foil of the PTFE plate are flat, the residual thickness layer is smaller under the condition of a certain range of back drilling large hole size, so as to meet the design requirements.

[0007] According to some embodiments of the application, the first back drilling large hole and the second back drilling large hole have the same hole diameter size, and the hole diameter size of the first back drilling large hole and the second back drilling large hole ranges from 1.05 mm to 2.50 mm.

[0008] According to some embodiments of the application, the pre-drilling hole has a hole diameter size that is 0.20 mm larger than the hole diameter size of the through hole.

[0009] According to some embodiments of the application, when the number of through holes is greater than or equal to 2, the hole edge distance between adjacent through holes is greater than or equal to 0.4 mm.

[0010] According to some embodiments of the application, when the number of through holes is equal to 1, the hole diameter size of the second back drilling large hole is greater than or equal to 0.40 mm larger than the hole diameter size of the through hole.

[0011] According to some embodiments of the application, when processing the second back drilling large hole on the SS surface of the PTFE plate, the feed rate of the drill bit is reduced from 1 m / min to 0.5 m / min.

[0012] According to some embodiments of the application, a plurality of through holes are arranged in the first back drilling large hole and the second back drilling large hole.

[0013] According to some embodiments of the application, a residual thickness layer is arranged between the first back drilling large hole and the second back drilling large hole, and the thickness of the residual thickness layer is greater than or equal to 0.30 mm.

[0014] Additional aspects and advantages of the application will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0015] The application will be further described below in conjunction with the drawings and embodiments, wherein: Figure 1 A flowchart of a method for double-sided back-drilling of a PTFE plate according to an embodiment of the present application is shown in FIG. 1. Figure 2 A structure diagram of a PTFE plate after processing a through hole according to an embodiment of the present application is shown in FIG. 2. Figure 3 A structure diagram of a PTFE plate after processing a first back-drilling large hole according to an embodiment of the present application is shown in FIG. 3. Figure 4 A structure diagram of a PTFE plate after processing a pre-drilling hole according to an embodiment of the present application is shown in FIG. 4. Figure 5 A structure diagram of a PTFE plate after processing a second back-drilling large hole according to an embodiment of the present application is shown in FIG. 5. Figure 6 A positional relationship diagram among a through hole, a pre-drilling hole and a second back-drilling large hole when the number of through holes of a PTFE plate is one according to an embodiment of the present application is shown in FIG. 6. Figure 7 A positional relationship diagram among a through hole, a pre-drilling hole and a second back-drilling large hole when the number of through holes of a PTFE plate is four according to an embodiment of the present application is shown in FIG. 7. The reference signs are as follows: through hole 100, first back-drilling large hole 200, pre-drilling hole 300, second back-drilling large hole 400, and residual thickness layer 500. DETAILED DESCRIPTION

[0016] In the description of the present application, the first and the second are only used for distinguishing technical features for the purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0017] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be understood in a broad sense, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0018] Reference Figures 1 to 7 The present application discloses a method for double-sided back-drilling of a PTFE plate, which comprises the following steps: S1: taking a PTFE plate and processing a plurality of through holes 100 at predetermined positions; S2: processing a first back-drilling large hole 200 on the CS surface of the PTFE plate; S3: processing a plurality of pre-drilling holes 300 on the SS surface of the PTFE plate, the pre-drilling holes 300 are coaxially arranged with the through holes 100, and the hole diameter size of the pre-drilling holes 300 is larger than that of the through holes 100; and S4: processing a second back-drilling large hole 400 on the SS surface of the PTFE plate.

[0019] PTFE plate is a polytetrafluoroethylene plate, and the through hole 100 is processed to meet specific functional requirements and technical requirements. First, the through hole 100 realizes electrical interconnection between layers. In a multi-layer PTFE circuit board, different conductive layers need to be connected to each other to form a complete circuit. The through hole is formed by drilling a hole in the insulating PTFE medium layer and metalizing the hole wall. The hole wall is plated with copper, thereby providing a current path for signal lines on different layers. Second, the through hole 100 provides a positioning reference for the processing of other holes. Back-drilling requires high concentricity alignment. The through hole 100 provides a positioning reference for the subsequent processing of the first back-drilled large hole 200, the second back-drilled large hole 400, and the pre-drilled hole 300. When drilling PTFE material, the drill bit extends along the existing through hole, effectively reducing drill bit drift and vibration, thereby improving back-drilling accuracy and hole wall quality.

[0020] Referring to Figure 6 and Figure 7 When the number of through holes 100 is one, the first back-drilled large hole 200, the second back-drilled large hole 400, and the pre-drilled hole 300 are coaxially arranged with the through hole 100. When the number of through holes 100 is greater than one, the through hole 100 is coaxially arranged with the pre-drilled hole 300.

[0021] Referring to Figure 3 When processing the first back-drilled large hole 200, the drill bit processes the CS surface. Since the second back-drilled large hole 400 has not been processed, the drill bit does not need to be pre-drilled when processing the first back-drilled large hole 200. Because the thickness of the residual thickness layer 500 is sufficient to support the impact force of the drill bit when processing the first back-drilled large hole 200.

[0022] Referring to Figure 4 , Figure 6 and Figure 7 After the first back-drilled large hole 200 is processed, the pre-drilled hole 300 is processed on the SS surface. The through hole 100 is used as a reference, and the pre-drilled hole 300 is coaxially arranged with the through hole 100. The processing depth of the pre-drilled hole 300 should be pre-set to ensure that there is enough thickness of the residual thickness layer 500 to resist the impact of the drill bit on the residual thickness layer 500, so that the residual thickness layer 500 remains flat. It should be noted that flat means that the inner base material and inner copper foil of the PTFE plate do not deform significantly, and the through hole 100 in the residual thickness layer 500 does not bend significantly. The size of the pre-drilled hole 300 should be larger than the through hole and smaller than the first back-drilled large hole 200 and the second back-drilled large hole 400.

[0023] After the pre-drilling 300, the second back-drilling large hole 400 is processed on the SS surface, at this time the drill bit reduces the feed rate of the drill bit, thereby reducing the impact force of the drill bit on the residual thick layer 500, so as to make the thickness of the residual thick layer 500 smaller under a certain range of back-drilling large hole size, while ensuring the flatness of the inner layer base material and the inner layer copper foil of the PTFE plate, to meet the design requirements.

[0024] In some embodiments, with reference to Figure 5 , the first back-drilling large hole 200 and the second back-drilling large hole 400 have the same hole diameter size, and the hole diameter size of the first back-drilling large hole 200 and the second back-drilling large hole 400 ranges from 1.05mm to 2.50mm, when the hole diameter size of the first back-drilling large hole 200 and the second back-drilling large hole 400 is less than 1.00mm, most of the PTFE plate designs can meet this requirement, it should be noted that when the hole diameter size of the first back-drilling large hole 200 and the second back-drilling large hole 400 is less than 1.00mm, the thickness of the residual thick layer 500 needs to be greater than 0.25mm, in the traditional double-sided back-drilling of the PTFE plate, that is, without the need to increase the pre-drilling 300, immediately after the first back-drilling large hole 200 is processed on the CS surface, the second back-drilling large hole 400 is processed on the SS surface, when the hole diameter size of the first back-drilling large hole 200 and the second back-drilling large hole 400 is less than 1.00mm, and the thickness of the residual thick layer 500 is greater than 0.25mm, the pre-drilling 300 does not need to be set to still ensure the flatness of the inner layer base material and the inner layer copper foil of the PTFE plate; when the hole diameter size of the first back-drilling large hole 200 and the second back-drilling large hole 400 is greater than 2.50mm, the size of the residual thick layer 500 required for design is larger, through testing, when the hole diameter size of the first back-drilling large hole 200 and the second back-drilling large hole 400 is 3.00mm and 3.50mm, and the thickness of the residual thick layer 500 is set to 1.00mm, the inner layer base material and the inner layer copper foil of the PTFE plate will still appear obvious deformation, therefore, when the hole diameter size of the first back-drilling large hole 200 and the second back-drilling large hole 400 exceeds 2.50mm, the improvement brought by the method is not obvious, therefore, the hole diameter size of the first back-drilling large hole 200 and the second back-drilling large hole 400 is limited to the range of 1.05mm to 2.50mm in the method, and the specific improvement effect is shown in Table 1:

[0025] Table 1 As can be seen from Table 1, when the hole diameter size of the first back-drilling large hole 200 and the second back-drilling large hole 400 ranges from 1.05mm to 2.50mm, the method can effectively reduce the thickness of the residual thick layer 500.

[0026] In some embodiments, with reference to Figure 6 and Figure 7, the diameter of the pre-drilled hole 300 is 0.20 mm larger than that of the through hole 100, that is, the edge distance between the pre-drilled hole 300 and the through hole 100 is 0.10 mm, and the pre-drilled hole 300 is arranged to remove part of the material first, so that the cutting force required by the drill bit is smaller when the second back-drilling large hole 400 is processed subsequently, and the impact force of the drill bit on the residual thickness layer 500 is also lower. When the edge distance between the pre-drilled hole 300 and the through hole 100 is 0.10 mm, the drill bit can quickly cut off the material, and it needs to be understood that the diameter of the pre-drilled hole 300 is only one choice in the method, and when the diameter of the through hole 100 and the diameter of the first back-drilling large hole 200 are too different, the diameter of the pre-drilled hole 300 and the diameter of the through hole 100 also need to be increased accordingly. At this time, the pre-drilled hole 300 can be processed multiple times, and the diameter of each drilling hole is increased by 0.20 mm; for example, when the diameter of the through hole 100 is 0.50 mm, and the diameter of the first back-drilling large hole 200 and the second back-drilling large hole 400 is 2.00 mm, the pre-drilled hole 300 can be processed multiple times, the first processing size is 0.70 mm, the second processing size is 0.90 mm, and the process is repeated until the pre-drilled hole 300 is finally 1.50 mm. The second back-drilling large hole 400 is processed on the SS surface.

[0027] In some embodiments, referring to Figure 7 When the number of through holes 100 is greater than or equal to 2, the hole edge distance between adjacent through holes 100 is greater than or equal to 0.4 mm. Since the diameter of the pre-drilled hole 300 is 0.20 mm larger than that of the through hole, when the number of through holes 100 is greater than or equal to 2, the hole edge distance between adjacent through holes 100 is greater than or equal to 0.4 mm, so as to prevent the pre-drilled holes 300 from intersecting or being offset, thereby affecting the pre-drilling effect, Figure 7 The positional relationship between the through hole 100, the pre-drilled hole 300 and the second back-drilling large hole 400 when the number of through holes 100 is 4 is given in

[0028] In some embodiments, referring to Figure 6When the number of through holes 100 = 1, the hole diameter size of the second back drilling large hole 400 is greater than the hole diameter size of the through hole 100 by 0.40 mm or more, when the hole diameter size of the second back drilling large hole 400 is less than the hole diameter size of the pre-drilling hole 300 by 0.40 mm or less, the pre-drilling hole 300 does not need to be set, and the machining of the second back drilling large hole 400 can be directly performed, at this time, the material thickness between the second back drilling large hole 400 and the through hole 100 is small, and the SS surface can be directly machined for the second back drilling large hole 400, at this time, the drill bit can be set to a smaller feed speed when machining the second back drilling large hole 400, so that the impact force of the drill bit on the residual thick layer 500 is reduced, and the inner layer base material and the inner layer copper foil of the PTFE plate can be kept flat during machining of the second back drilling large hole 400. Therefore, the hole diameter size of the second back drilling large hole 400 is greater than the hole diameter size of the through hole 100 by 0.40 mm or more, and the pre-drilling hole 300 needs to be set.

[0029] In some embodiments, when machining the second back drilling large hole 400 on the SS surface of the PTFE plate, the feed speed of the drill bit is reduced from 1 m / min to 0.5 m / min. Reducing the feed speed of the drill bit means reducing the machining speed of the second back drilling large hole 400, thereby reducing the impact force of the drill bit on the residual thick layer 500. It should be noted that reducing the feed speed of the drill bit from 1 m / min to 0.5 m / min is only one option for the feed speed of the drill bit in this method. The purpose is to reduce the impact force of the drill bit on the residual thick layer 500 by reducing the feed speed of the drill bit. Here, the feed speed of the drill bit can be set according to the actual situation and is not limited to 0.5 m / min.

[0030] In some embodiments, referring to Figures 2 to 7 , several through holes 100 are arranged in the first back drilling large hole 200 and the second back drilling large hole 400. The through hole 100 is used as a reference for machining other holes. After machining the first back drilling large hole 200 and the second back drilling large hole 400, the through hole 100 is only arranged on the residual thick layer 500.

[0031] In some embodiments, referring to Figure 5 , the residual thick layer 500 is arranged between the first back drilling large hole 200 and the second back drilling large hole 400. The thickness of the residual thick layer 500 is ≥0.30 mm. Since the hole diameter size range of the first back drilling large hole 200 and the second back drilling large hole 400 in this method is 1.05 mm to 2.50 mm, the required thickness of the residual thick layer 500 is ≥0.30 mm. Therefore, the thickness of the residual thick layer 500 is ≥0.30 mm.

[0032] Each technical feature of the above-described embodiments can be combined with any other technical feature, and for the sake of brevity, not all possible combinations are described, but it is understood that the scope of the disclosure encompasses all such possible combinations.

[0033] Of course, the present application is not limited to the above-described embodiments, and those skilled in the art can make equivalent modifications or substitutions without departing from the spirit of the present application, and such equivalent modifications or substitutions are included in the scope of the present application as defined by the claims.

Claims

1. A method for double-sided back drilling of PTFE sheets, characterized in that, include: S1: Take a PTFE sheet and machine several through holes (100) at the predetermined positions. S2: Drill the first back-drilled large hole (200) on the CS side of the PTFE sheet; S3: A number of pre-drilled holes (300) are processed on the SS surface of the PTFE sheet. The pre-drilled holes (300) are coaxially arranged with the through holes (100). The diameter of the pre-drilled holes (300) is larger than that of the through holes (100). S4: Drill a second large back hole (400) on the SS side of the PTFE sheet.

2. The method for double-sided back drilling of PTFE sheets according to claim 1, characterized in that, The first back-drilled large hole (200) and the second back-drilled large hole (400) have the same hole diameter, and the hole diameter range of the first back-drilled large hole (200) and the second back-drilled large hole (400) is 1.05mm to 2.50mm.

3. The method for double-sided back drilling of PTFE sheets according to claim 1, characterized in that, The diameter of the pre-drilled hole (300) is 0.20 mm larger than that of the through hole (100).

4. The method for double-sided back drilling of PTFE sheets according to claim 1, characterized in that, When the number of through holes (100) is ≥2, the hole edge distance between adjacent through holes (100) is ≥0.4mm.

5. The method for double-sided back drilling of PTFE sheets according to claim 1, characterized in that, When the number of through holes (100) is 1, the diameter of the second back-drilled large hole (400) is more than 0.40 mm larger than the diameter of the through hole (100).

6. The method for double-sided back drilling of PTFE sheet according to claim 1, characterized in that, When machining the second back-drilled large hole (400) on the SS surface of the PTFE sheet, the feed rate of the drill bit is reduced from 1 m / min to 0.5 m / min.

7. The method for double-sided back drilling of PTFE sheets according to claim 1, characterized in that, Several of the through holes (100) are provided in the first back-drilled large hole (200) and the second back-drilled large hole (400).

8. The method for double-sided back drilling of PTFE sheet according to claim 1, characterized in that, A residual thickness layer (500) is provided between the first back-drilled large hole (200) and the second back-drilled large hole (400), and the thickness of the residual thickness layer (500) is ≥0.30mm.

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