Method for manufacturing polytetrafluoroethylene buried cavity plate
Through fast pressure method and rubber-resistance wire/trough structure, the problems of incomplete and collapse of hollow cavity in the production of PTFE buried cavity plates are solved, and large-size and high-integrity cavity plates are realized, which improves electrical performance and Signal integrity.
Patent Information
- Application Number
- CN202411567005.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-05
- Publication Date
- 2025-02-14
AI Technical Summary
The prior art is difficult to effectively produce PTFE buried cavity plates, resulting in small and incomplete cavity sizes. The soft pressing of the PTFE board is prone to cavity collapse, which cannot meet the requirements of high-frequency and high-speed signal integrity.
The semi-finished plate, the second adhesive sheet and the third copper clad plate are bonded by fast pressure. By setting a rubber-resisting wire and a rubber-resisting groove at the lower end of the semi-finished plate, the flow glue is prevented from invading the line, and the resistor is set in the cavity groove. Flow plates to enhance structural stability.
The large-size and high integrity cavity plate production is achieved, which reduces the dielectric constant and loss factor, improves electrical performance and signal integrity, and avoids the problem of cavity collapse.
Smart Images
Figure CN119450978A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of PCB boards, and in particular relates to a method for manufacturing a polytetrafluoroethylene buried cavity board. Background Art
[0002] With the continuous development of science and technology, signal transmission is moving towards a higher frequency and higher speed era. Exploring and tapping high-speed and high-frequency PCB boards with more advantageous electrical performance is the pursuit of the times. The role of the buried cavity board is to replace the board above the line with air, which can bring lower dielectric constant and loss coefficient in terms of electricity, thereby reducing the loss of signal transmission and improving signal integrity. In the PCB industry, the material of the buried cavity board is the conventional hard FR4 material. After processing and making the empty slot, it is pressed with a conventional hot press to form a PCB board with a buried cavity. However, the cavity size prepared in this way is small, usually 1mm (width) * 0.1mm (height), and the cavity is easy to sink, incomplete, and has more glue flow; the pressing pressure of the conventional buried cavity manufacturing process of FR4 is high and the time is long, which only meets the production of FR4 materials, but does not meet the production requirements of soft polytetrafluoroethylene cavity boards (easy to cause cavity compaction). It has production limitations and is difficult to meet the increasing signal integrity requirements of high frequency and high speed.
[0003] Based on the above problems, this application document proposes a method for manufacturing a polytetrafluoroethylene buried cavity plate to improve the above problems. Summary of the invention
[0004] The purpose of the present invention is to provide a method for manufacturing a polytetrafluoroethylene buried cavity board, by manufacturing a semi-finished board, and then pressing the semi-finished board, a second adhesive sheet and a third copper clad board by fast pressing to manufacture a cavity board. This structure reduces the dielectric constant and the loss factor, improves the electrical performance and signal integrity, and overcomes the shortcoming that the polytetrafluoroethylene board is easy to collapse under soft pressing, and has the advantages of large cavity size, high integrity, and no collapse.
[0005] The technical solution adopted by the present invention is as follows: A method for manufacturing a polytetrafluoroethylene buried cavity plate comprises the following steps: Step 1, processing the first copper clad laminate, the second copper clad laminate and the third copper clad laminate respectively to make connection holes and patterns; Step 2, pressing and bonding the first copper clad laminate, the first adhesive sheet, and the second copper clad laminate into a semi-finished board; Step 3, processing the semi-finished board so that a glue blocking line, a glue blocking groove, and a cavity groove are formed at the lower end of the semi-finished board; Step 4: laser cutting the second adhesive sheet to form a window area inside the second adhesive sheet; Step six, bonding the semi-finished board, the second bonding sheet, and the third copper clad board by fast pressing to obtain a cavity board; Wherein, the first copper clad laminate, the second copper clad laminate and the third copper clad laminate are all made of polytetrafluoroethylene.
[0006] In a preferred embodiment, the spatial arrangement order of the internal components of the semi-finished board is as follows, from the top to the bottom: a first copper clad board, a first adhesive sheet, and a second copper clad board, and the lower end surface of the first copper clad board and the first adhesive sheet as well as the first adhesive sheet and the upper end surface of the second copper clad board are bonded to each other.
[0007] In a preferred embodiment, the controlled depth of the cavity groove is denoted as H, the thickness of the first adhesive sheet is denoted as H1, the thickness of the second copper clad laminate is denoted as H2, and H=H1+H2.
[0008] In a preferred embodiment, the distance between the glue blocking line and the cavity groove ranges from 0.3 mm to 0.5 mm. Preferably, the distance between the glue blocking line and the cavity groove is 0.35 mm.
[0009] In a preferred embodiment, the distance between the glue blocking groove and the cavity groove ranges from 1.5 mm to 2 mm. Preferably, the distance between the glue blocking groove and the cavity groove is 1.65 mm.
[0010] In a preferred embodiment, the window area and the cavity groove are adapted to each other, the distance between the edge of the window area and the edge of the cavity groove is in the range of 0.3 mm to 1 mm, and the edge of the window area is located outside the edge of the cavity groove. Preferably, the distance between the edge of the window area and the edge of the cavity groove is 0.55 mm.
[0011] In a preferred embodiment, the spatial arrangement order of the internal components of the cavity plate is as follows, from the top to the bottom: a semi-finished board, a second adhesive sheet and a third copper clad board, and the lower end surface of the semi-finished board and the second adhesive sheet as well as the second adhesive sheet and the upper end surface of the third copper clad board are bonded to each other.
[0012] In a preferred embodiment, the step of rapid pressing comprises: The first stage pre-pressing, the pressure of the first stage pre-pressing is 3kg-10kg, the pre-pressing time is 10s-50s, the pre-pressing temperature is 180°C, preferably, the pressure of the first stage pre-pressing is 5kg, and the pre-pressing time is 20s; The second stage molding, the second stage molding pressure is 80kg ~ 150kg, the molding time is 350s ~ 500s, the molding temperature is 180 ° C. Preferably, the second stage molding pressure is 100kg, the molding time is 400s.
[0013] In a preferred embodiment, the steps before step 5 further include: The semi-finished board, the second adhesive sheet and the third copper clad board are pre-stacked by rivet alignment.
[0014] In a preferred embodiment, in step 5, the steps after the rapid pressing further include: The plate after quick pressing is baked by a baking device, the baking temperature is 145° C. to 170° C., and the baking time is 1 hour to 1.5 hours. Preferably, the baking temperature is 160° C., and the baking time is 1 hour.
[0015] The technical effects achieved by the present invention are: The present invention manufactures a semi-finished board by pressing a first copper-clad board, a first adhesive sheet and a second copper-clad board, and then presses the semi-finished board, the second adhesive sheet and the third copper-clad board in a fast pressing manner to manufacture a cavity board, thereby reducing the dielectric constant and the loss factor from a structural aspect, greatly improving the electrical performance and signal integrity of the board, and also overcoming the disadvantage that the polytetrafluoroethylene board material is easy to collapse the cavity due to soft pressing. The manufactured cavity is large enough and has high cavity integrity, and has the advantages of large-size cavity manufacturability and no cavity collapse. Compared with the parameters of conventional hot press machines, the fast pressing method has low pressure and short pressing time, thereby ensuring the integrity of the cavity and taking into account the reliability of the board at the same time; The present invention provides a glue blocking line and a glue blocking groove at the lower end of the semi-finished plate to block and store the overflowed colloid, thereby preventing the flowing glue from invading the circuit. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 is a flow chart of a method for manufacturing a polytetrafluoroethylene cavity plate in Embodiment 1 of the present invention; Figure 2 is a schematic structural diagram of a polytetrafluoroethylene cavity plate in Embodiment 1 of the present invention; Figure 3 is a top view of the polytetrafluoroethylene cavity plate in Example 1 of the present invention; Figure 4 It is a schematic diagram of the structure of the polytetrafluoroethylene cavity plate in the second embodiment of the present invention.
[0017] In the accompanying drawings, the components represented by the reference numerals are listed as follows: 11. First copper clad laminate; 12. Second copper clad laminate; 13. Third copper clad laminate; 14. First adhesive sheet; 15. Second adhesive sheet; 16. Blocker; 20. Semi-finished board; 21. Glue blocking line; 22. Glue blocking groove; 23. Cavity groove; 24. Window area; 30. Cavity board. DETAILED DESCRIPTION
[0018] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.
[0019] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0020] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The phrase "in a preferred embodiment" that appears in different places in this specification does not refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.
[0021] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included. Embodiment 1
[0022] Please see attached Figures 1 to 3 As shown in the figure, it is a first embodiment of the present invention, which provides a method for manufacturing a polytetrafluoroethylene buried cavity plate, comprising the following steps: Step 1: Process the first copper clad laminate 11, the second copper clad laminate 12 and the third copper clad laminate 13 respectively to make connection holes and patterns, wherein the first copper clad laminate 11, the second copper clad laminate 12 and the third copper clad laminate 13 are all processed by conventional PCB processing technology, and the process content includes: drilling (including: connection holes, rivet positioning holes, etc.), pattern production, etc., wherein the first copper clad laminate, the second copper clad laminate and the third copper clad laminate are all made of polytetrafluoroethylene; Step 2: Pre-stack and rivet the first copper clad laminate 11, the first adhesive sheet 14, and the second copper clad laminate 12 in order through the rivet positioning holes, and press and bond them through a conventional hot press after riveting to obtain a semi-finished board 20, wherein the lower end surface of the first copper clad laminate 11 and the upper end surface of the first adhesive sheet 14, as well as the lower end surface of the first adhesive sheet 14 and the upper end surface of the second copper clad laminate 12 are all bonded to each other; Step 3: Process the semi-finished board 20 so that a glue blocking line 21, a glue blocking groove 22, and a cavity groove 23 are formed at the lower end of the semi-finished board 20, and the glue blocking line 21 surrounds the outer side of the cavity groove 23. In this embodiment: The line width of the rubber blocking line 21 is 0.132 mm, the line thickness is 0.015 mm, and the projection distance between the rubber blocking line 21 and the cavity groove 23 on the horizontal plane is 0.35 mm; The size of the glue blocking groove 22 is 6 mm (length) * 0.6 mm (width) * 0.65 mm (height), and the projection distance between the glue blocking groove 22 and the cavity groove 23 on the horizontal plane is 1.65 mm; The size of the cavity groove 23 is 8.7 mm (length) * 7.1 mm (width), and the depth of the cavity groove 23 is the sum of the thickness of the first adhesive sheet 14 and the second copper clad laminate 12, without damaging the first copper clad laminate 11; Step 4: Laser cutting the second adhesive sheet 15 so that a window area 24 is formed inside the second adhesive sheet 15, the window area 24 is matched with the cavity groove 23, and on the horizontal projection plane, the cavity groove 23 is located inside the window area 24, wherein the distance between the edge of the window area 24 and the edge of the cavity groove 23 is 0.55 mm, wherein in this embodiment, the size of the window area 24 is 9.8 mm (length) * 8.2 mm (width); Step 5: Pre-stack and rivet the semi-finished board 20, the second adhesive sheet 15, and the third copper clad board 13 in order through the rivet positioning holes, the glue resistance line 21 and the second adhesive sheet 15 do not contact, and the lower end surface of the semi-finished board 20 and the upper end surface of the second adhesive sheet 15, as well as the lower end surface of the second adhesive sheet 15 and the upper end surface of the third copper clad board 13 are all in contact with each other, the semi-finished board 20, the second adhesive sheet 15, and the third copper clad board 13 are bonded by quick pressing, and then the quick-pressed panels are baked by baking equipment, the baking temperature is 160°C, the baking time is 1h, and the cavity board 30 is obtained after baking; Among them, the specific parameters of the quick pressing method are: the quick pressing temperature of the semi-finished board 20, the second adhesive sheet, and the third copper clad board 13 is 180°C, and the pressing is divided into two stages. The first stage is pre-pressing: pressure 5kg, time 20s; the second stage is molding: pressure 100kg, time 400s. The material of the first adhesive sheet 14 is polyphenylene ether, and the material of the second adhesive sheet 15 is epoxy resin.
[0023] In this embodiment, during the rapid pressing process, the setting of the glue blocking line 21 can reduce the overflow of the glue during rapid pressing and avoid the intrusion of the glue into the circuit. After the glue is melted, part of the glue flows into the glue blocking groove 22. Through the cooperation of multiple glue blocking grooves 22, the amount of glue squeezed into the cavity groove 23 during the rapid pressing process can be reduced, thereby achieving the purpose of reducing or avoiding the rapid pressing of the cavity groove 23. Overflow glue overflow. At the same time, compared with the conventional hot press parameters, the above-mentioned technical scheme has low pressure and short pressing time in the rapid pressing parameters, which ensures the integrity of the cavity while taking into account the reliability of the board. At the same time, it can breakthrough support the production of a polytetrafluoroethylene buried cavity board 30 with a soft board material, reduce the dielectric constant and loss factor from the structural aspect, and greatly improve the electrical performance and signal integrity of the board. The polytetrafluoroethylene buried cavity board 30 produced by this process overcomes the disadvantage that the polytetrafluoroethylene board material is soft and easy to collapse the cavity during pressing. The produced cavity is large enough and has high cavity integrity. It has the advantages of large-size cavity producibility and no cavity collapse.
[0024] In a specific embodiment, the projection shapes of the cavity groove 23 and the window area 24 on the horizontal plane are both squares, and the projection figure of the cavity groove 23 is located inside the projection figure of the window area 24. The side length of the cavity groove 23 is L, and the side length of the window area 24 is L+2*0.55.
[0025] In another specific embodiment, the projection shapes of the cavity groove 23 and the window area 24 on the horizontal plane are both circular, and the projection shape of the cavity groove 23 is located inside the projection shape of the window area 24. The radius of the cavity groove 23 is r, and the radius of the window area 24 is r+0.55. Embodiment 2
[0026] Please see attached Figure 4 As shown, this embodiment is further optimized on the basis of the first embodiment. The difference between this embodiment and the first embodiment is that a baffle 16 is installed inside the cavity groove 23 to further prevent the flow of glue from invading the circuit during the rapid pressing process. Specifically, the following steps are included: St1: Process the first copper clad laminate 11, the second copper clad laminate 12 and the third copper clad laminate 13 respectively to make connection holes and patterns, wherein the first copper clad laminate 11, the second copper clad laminate 12 and the third copper clad laminate 13 are all processed by conventional PCB processing technology, and the process content includes: drilling (including: connection holes, rivet positioning holes, etc.), pattern production, etc.; St2: Pre-stack and rivet in the order of the first copper clad laminate 11, the first adhesive sheet 14, and the second copper clad laminate 12 through rivet positioning holes, and press and bond them through a conventional hot press after riveting to obtain a semi-finished plate 20, wherein the lower end surface of the first copper clad laminate 11 and the upper end surface of the first adhesive sheet 14, as well as the lower end surface of the first adhesive sheet 14 and the upper end surface of the second copper clad laminate 12 are all in contact with each other, and an avoidance groove is provided inside the hot press, and the avoidance groove is matched with the T-shaped through groove; St3: Processing the semi-finished plate 20 so that a glue blocking line 21, a glue blocking groove 22, and a cavity groove 23 are formed at the lower end of the semi-finished plate 20, and the glue blocking line 21 surrounds the outer side of the cavity groove 23; St4: The spoiler 16 is sleeved inside the cavity groove 23 in a transition fit manner, wherein the spoiler 16 is made of aromatic polyamide, the projection shape of the spoiler 16 on the horizontal plane is the same as the projection shape of the cavity groove 23, and the height of the spoiler 16 is the sum of the thicknesses of the first adhesive sheet 14, the second copper clad plate 12, and the second adhesive sheet 15; St5: laser cutting the second adhesive sheet 15 so that a window area 24 is formed inside the second adhesive sheet 15, and the window area 24 is matched with the cavity groove 23; St6: Pre-stack and rivet in the order of the semi-finished board 20, the second adhesive sheet 15, and the third copper clad board 13 through the rivet positioning holes, the glue resistance line 21 and the second adhesive sheet 15 do not contact, and the lower end surface of the semi-finished board 20 and the upper end surface of the second adhesive sheet 15, as well as the lower end surface of the second adhesive sheet 15 and the upper end surface of the third copper clad board 13 are all in contact with each other, the semi-finished board 20, the second adhesive sheet 15, and the third copper clad board 13 are bonded by quick pressing, and then the quick-pressed panels are baked by baking equipment, the baking temperature is 160°C, the baking time is 1h, and the cavity board 30 is obtained after baking; Among them, the specific parameters of the quick pressing method are: the quick pressing temperature of the semi-finished board 20, the second adhesive sheet, and the third copper clad board 13 is 180°C, and the pressing is divided into two stages. The first stage is pre-pressing: pressure 5kg, time 20s; the second stage is molding: pressure 100kg, time 400s. The material of the first adhesive sheet 14 is polyphenylene ether, and the material of the second adhesive sheet 15 is epoxy resin.
[0027] In this embodiment, aromatic polyamide is a high-performance engineering plastic, which is well-known for its excellent heat resistance, chemical resistance and mechanical properties. Its softening temperature is usually above 400°C, which is much higher than the softening temperatures of polyphenylene ether and epoxy resin. By arranging a baffle 16 made of aromatic polyamide inside the cavity groove 23, during the rapid pressing process, when the first adhesive sheet 14 made of polyphenylene ether and the second adhesive sheet 15 made of epoxy resin soften and flow, the baffle 16 can still maintain good mechanical properties and will not deform, thereby blocking the flowing glue through the baffle 16 to prevent the flowing glue from invading the circuit.
[0028] The above is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention shall be implemented according to the conventional means in the art unless otherwise specified and limited.
Claims
1. A method for manufacturing a polytetrafluoroethylene buried cavity plate, characterized in that: The following steps are involved: Step 1, processing the first copper clad laminate, the second copper clad laminate and the third copper clad laminate respectively to make connection holes and patterns; Step 2, pressing and bonding the first copper clad laminate, the first adhesive sheet, and the second copper clad laminate into a semi-finished board; Step 3, processing the semi-finished board so that a glue blocking line, a glue blocking groove, and a cavity groove are formed at the lower end of the semi-finished board; Step 4: laser cutting the second adhesive sheet to form a window area inside the second adhesive sheet; Step 5, bonding the semi-finished board, the second bonding sheet, and the third copper clad board by fast pressing to obtain a cavity board; Wherein, the first copper clad laminate, the second copper clad laminate and the third copper clad laminate are all made of polytetrafluoroethylene.
2. A method for manufacturing a polytetrafluoroethylene buried cavity plate according to claim 1, characterized in that: The spatial arrangement order of the internal components of the semi-finished board is as follows, from the top to the bottom: the first copper clad board, the first adhesive sheet, the second copper clad board, and the lower end surface of the first copper clad board and the first adhesive sheet as well as the first adhesive sheet and the upper end surface of the second copper clad board are bonded to each other.
3. The method for manufacturing a polytetrafluoroethylene cavity buried plate according to claim 1, characterized in that: The controlled depth of the cavity groove is recorded as H, the thickness of the first adhesive sheet is recorded as H1, the thickness of the second copper clad laminate is recorded as H2, and H=H1+H2.
4. The method for manufacturing a polytetrafluoroethylene cavity buried plate according to claim 1, characterized in that: The distance between the glue blocking line and the cavity groove ranges from 0.3 mm to 0.5 mm.
5. The method for manufacturing a polytetrafluoroethylene cavity buried plate according to claim 1, characterized in that: The distance between the glue blocking groove and the cavity groove ranges from 1.5 mm to 2 mm.
6. The method for manufacturing a polytetrafluoroethylene cavity buried plate according to claim 1, characterized in that: The window area and the cavity groove are matched, and the distance between the edge of the window area and the edge of the cavity groove ranges from 0.3mm to 1mm.
7. The method for manufacturing a polytetrafluoroethylene cavity buried plate according to claim 1, characterized in that: The spatial arrangement order of the internal components of the cavity plate is as follows, from the top to the bottom: a semi-finished board, a second adhesive sheet and a third copper clad board, and the lower end surface of the semi-finished board and the second adhesive sheet as well as the second adhesive sheet and the upper end surface of the third copper clad board are bonded to each other.
8. The method for manufacturing a polytetrafluoroethylene cavity buried plate according to claim 1, characterized in that: The step of rapid pressing comprises: The first stage of pre-pressing, the pressure of the first stage of pre-pressing is 3kg to 10kg, and the pre-pressing time is 10s to 50s; The second stage of molding, the pressure of the second stage of molding is 80kg-150kg, and the molding time is 350s-500s.
9. The method for manufacturing a polytetrafluoroethylene cavity buried plate according to claim 1, characterized in that: The steps before step 5 also include: The semi-finished board, the second adhesive sheet and the third copper clad board are pre-stacked by rivet alignment.
10. The method for manufacturing a polytetrafluoroethylene cavity buried plate according to claim 1, characterized in that: In the step 5, the steps after the quick pressing also include: The plate after quick pressing is baked by a baking device, the baking temperature is 145° C. to 170° C., and the baking time is 1 hour to 1.5 hours.