Super high-rise unequal-thickness rigid-flex printed circuit board and preparation method thereof

Abstract

The invention provides a super high-rise unequal-thickness rigid-flex board and a preparation method thereof. The preparation method comprises the following steps: (1) sequentially stacking and fixing a rigid board, a solid bonding board, at least 20 layers of flexible boards, the solid bonding board and the rigid board to obtain a rigid-flex board blank; (2) sequentially stacking a buffer press fit material, the rigid-flex board blank and a buffer press fit material, and performing press fit treatment to obtain the rigid-flex board; the lead width precision tolerance of the flexible plate and the rigid plate is + / -10%. According to the preparation method provided by the invention, through a processing mode of expansion and shrinkage feedback, the problem of lamination deviation caused by material expansion and shrinkage change after core plate processing is improved; in addition, the problem of uneven stress caused by the height difference of different plate thicknesses is avoided through the use of the buffer pressing material, and the risk of local pressure loss caused by uneven stress is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of printed circuit boards, and in particular relates to an ultra-high-layer unequal-thickness rigid-flexible board and a preparation method thereof. Background Art

[0002] Rigid-flexible boards (R-FPC) have the characteristics of both flexible circuit boards (soft boards) and rigid printed boards (hard boards), providing a new way to connect electronic components, greatly reducing the number of connection points and the use of board-edge connectors. At the same time, it also improves the performance of the product, and is particularly suitable for the needs of the latest portable product market. In response to the market's demand for multi-component spatial combination installation, in order to meet customer customization and match customer space reasonable installation requirements, unequal thickness rigid-flexible boards have also come into being. However, rigid-flexible products have complex structures and a wide variety of types, and the difficulty of making rigid-flexible boards is already well known in the industry.

[0003] At present, domestic suppliers mainly use layered processing for this type of special rigid-flexible board, first processing the sub-board and then laminating and bonding the main board with it, and finally completing the processing. The main problems are as follows: (1) There is a serious height difference between the main board, sub-board and flexible board. During the lamination process, the uneven force on each area of ​​the board surface causes local decompression and delamination; (2) Multiple processing is required, the material shrinkage is inconsistent, and the problem of displacement is easy to occur after lamination.

[0004] In response to the problem of misalignment, CN 106581975A discloses a rigid-flexible board and a method for making the same, the method comprising: A. cutting the flexible board and punching out riveting holes, using a covering film to adhere both sides of the flexible board and pre-pressing it, and then roughening it; B. cutting the rigid board, punching out riveting holes, and performing blind groove processing; C. stacking the rigid board, prepreg, flexible board, prepreg, and rigid board in order, and using rivets to fix the positions of the riveting holes, and then placing them in a laminator for lamination to obtain a rigid-flexible board. This patent solves the problem of large expansion and contraction differences after lamination by improving the expansion and contraction problems that occur during the production of rigid-flexible boards, so as to avoid the occurrence of layer misalignment. However, this patent does not solve the problem of decompression and stratification of ultra-high-rise rigid-flexible boards.

[0005] In summary, it is necessary to provide a simpler and more effective method to solve the problems of mid-pressure coupling deviation and pressure loss delamination that may occur in the production process of rigid-flexible boards. Summary of the invention

[0006] The purpose of the present invention is to provide an ultra-high-rise unequal thickness rigid-flex board and a preparation method thereof. The present invention improves the problem of lamination deviation caused by material expansion and contraction changes after core board processing through a processing method of expansion and contraction feedback.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing an ultra-high-rise rigid-flex board of unequal thickness, the preparation method comprising the following steps:

[0009] (1) stacking a rigid board, a solid bonding board, at least 20 layers of flexible boards, a solid bonding board, and a rigid board in sequence, and fixing them to obtain a rigid-flexible bonded board blank;

[0010] (2) stacking the buffer pressing material, the rigid-flexible board blank, and the buffer pressing material in order, and obtaining the rigid-flexible board after pressing;

[0011] The wire width accuracy tolerance of the flexible board and the rigid board is ±10%, for example, it can be -10%, -6%, -2%, 0%, 2%, 6% or 10%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0012] The present invention improves the problem of lamination deviation caused by material expansion and contraction after processing of the rigid-flexible board by controlling the wire width precision tolerance (i.e., expansion and contraction feedback) of the flexible board and the rigid board; at the same time, the inter-layer alignment accuracy is improved;

[0013] In addition, the present invention uses a buffer pressing material to balance the pressure acting on the surface of the rigid-flexible board blank, thereby solving the risk of local pressure loss caused by uneven force.

[0014] In the present invention, if the wire width precision tolerance of the flexible board and the rigid board is too large, the impedance and current carrying capacity of the obtained rigid-flexible board will change, and poor welding may occur during the welding process.

[0015] It is worth noting that the super-high layer described in the present invention is: the number of flexible board layers in the rigid-flexible board is ≥ 20 layers, for example, it can be 20 layers, 21 layers, 22 layers, 23 layers, 24 layers, 25 layers or 26 layers, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] The unequal thickness in the present invention means that the rigid board has different thicknesses, which is called unequal thickness rigid-flex board. For specific design requirements, if higher mechanical strength or better heat dissipation performance is required in some areas, a thicker rigid layer can be used; while in places where there are strict requirements on space or weight, a thinner rigid layer can be used.

[0017] As a preferred technical solution of the present invention, the calculation formula for the wire width accuracy tolerance of the flexible board and the rigid board is:

[0018] (The wire width of the flexible board - the wire width of the rigid board) / the wire width of the flexible board×100%.

[0019] As a preferred technical solution of the present invention, before the stacking in step (1) of the present invention, the process further includes: cutting the flexible plate and punching out riveting holes, applying a covering film to both sides of the flexible plate and pre-pressing the two sides, and then performing a roughening treatment;

[0020] The rigid plate is cut, riveted holes are punched out and blind grooves are processed.

[0021] Preferably, the pre-pressing temperature is 90-100°C, for example, 90°C, 92°C, 94°C, 96°C, 98°C or 100°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the pre-pressing pressure is 30-60 kg / cm 2 , for example, it can be 30kg / cm 2 、35kg / cm 2 , 40kg / cm 2 , 45kg / cm 2 , 50kg / cm 2 、55kg / cm 2 or 60kg / cm 2 , but not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0023] Preferably, the pre-pressing time is 20 to 30 s, for example, it can be 20 s, 21 s, 22 s, 23 s, 24 s, 25 s, 26 s, 27 s, 28 s, 29 s or 30 s, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] Preferably, the fixing process in step (1) includes: using rivets to fix the riveting holes.

[0025] As a preferred technical solution of the present invention, a layer of solid adhesive plate is respectively arranged between adjacent flexible plates.

[0026] Preferably, the buffer lamination material in step (2) comprises a prepreg.

[0027] Preferably, the tensile strength of the prepreg is 150-170 MPa, for example, 150 MPa, 154 MPa, 158 MPa, 162 MPa, 166 MPa or 170 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] Preferably, the fluidity of the prepreg is 20%, and the amount of glue flow is 1.5 to 3 mm, for example, it can be 1.5 mm, 1.8 mm, 2.1 mm, 2.4 mm, 2.7 mm or 3 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] Preferably, the resin curing rate of the prepreg is 75-85%, for example, 75%, 77%, 79%, 81%, 83% or 85%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] As a preferred technical solution of the present invention, the temperature of the pressing treatment in step (2) is 200-220°C, for example, it can be 200°C, 204°C, 208°C, 212°C, 216°C or 220°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] In the present invention, the temperature of the pressing treatment is 200-220°C. If the treatment temperature is too high, the resin and other materials in the PCB substrate will be over-cured, the molecular structure will change, and the substrate will become hard and brittle. High temperature will also change the insulating material on the PCB board, resulting in a decrease in insulation resistance and changes in line impedance, which will affect the electrical performance; low treatment temperature will lead to incomplete curing of the resin and poor interlayer bonding. Incompletely cured resin may soften in a high temperature environment and cause the PCB board to deform, which will not only reduce the mechanical strength and heat resistance of the PCB, but also affect the installation and normal use of electronic components.

[0032] Preferably, the time for the pressing treatment in step (2) is 2.5 to 3.5 h, for example, it can be 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h, 3 h, 3.1 h, 3.2 h, 3.3 h, 3.4 h or 3.5 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] As a preferred technical solution of the present invention, the pressure of the pressing treatment in step (2) is 25 to 35 kg / cm 2 , for example, it can be 25kg / cm 2 , 27kg / cm 2 , 29kg / cm 2 、31kg / cm 2 、33kg / cm 2 or 35kg / cm 2 , but not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0034] In the present invention, the pressure of the pressing process is 25 to 35 kg / cm 2 If the processing pressure is too high, it will cause deformation of the substrate, damage to the internal structure of the material, thinning of the insulation layer or local defects. Too high pressure will change the physical size and shape of the circuit on the PCB board, thereby affecting the impedance of the circuit. Low processing pressure will cause delamination, voids and bubbles between layers. Due to low pressure, the material resin is not fully cured, the dielectric constant and thickness of the PCB board are uneven, which will cause changes in the line impedance, affect the transmission quality of the signal, and cause problems such as signal reflection and attenuation.

[0035] As a preferred technical solution of the present invention, the pressing process in step (2) further includes drilling, solder masking, surface treatment, testing and analysis, and milling.

[0036] As a preferred technical solution of the present invention, the surface treatment includes nickel immersion treatment and gold immersion treatment performed sequentially.

[0037] Preferably, the thickness of the nickel layer in the nickel plating treatment is 3 to 5 μm, for example, 3 μm, 3.4 μm, 3.8 μm, 4.2 μm, 4.6 μm or 5 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0038] Preferably, the thickness of the gold layer in the gold immersion treatment is 0.05-0.1 μm, for example, 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm or 0.1 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0039] As a preferred technical solution of the present invention, the test analysis is used to test the connectivity and insulation of the rigid-flex board.

[0040] Preferably, the drilling includes: providing interlayer via holes and realizing hole metallization.

[0041] Preferably, the solder resist comprises: obtaining a surface solder resist layer by a coating process.

[0042] Preferably, the milling process comprises: milling the obtained rigid-flex board into delivered unit units.

[0043] Preferably, the milling process also includes inspection and packaging for shipment.

[0044] Preferably, the inspection content includes: the appearance and size of the rigid-flex board.

[0045] As a preferred technical solution of the present invention, the method for preparing the ultra-high-rise unequal thickness rigid-flexible board provided in the first aspect of the present invention comprises the following steps:

[0046] (1) stacking a rigid board, a solid bonding board, at least 20 layers of flexible boards, a solid bonding board, and a rigid board in sequence, and fixing them to obtain a rigid-flexible bonded board blank;

[0047] A layer of solid adhesive plate is respectively arranged between adjacent flexible plates;

[0048] (2) stacking the buffer pressing material, the rigid-flexible board blank, and the buffer pressing material in order, and obtaining the rigid-flexible board after pressing;

[0049] The wire width accuracy tolerance of the flexible board and the rigid board is ±10%;

[0050] The temperature of the pressing treatment is 200-220°C, the time is 2.5-3.5 hours, and the pressure is 25-35 kg / cm 2 ;

[0051] (3) performing drilling, solder masking, surface treatment, testing and analysis, and milling on the rigid-flexible board described in step (2);

[0052] The surface treatment includes nickel immersion treatment and gold immersion treatment performed in sequence. The thickness of the nickel layer in the nickel immersion treatment is 3-5 μm, and the thickness of the gold layer in the gold immersion treatment is 0.05-0.1 μm.

[0053] In a second aspect, the present invention provides an ultra-high-rise rigid-flexible board with unequal thicknesses. The ultra-high-rise rigid-flexible board with unequal thicknesses is obtained by the preparation method provided in the first aspect.

[0054] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) The preparation method provided by the present invention solves the problem of lamination deviation caused by inconsistent material shrinkage through a processing method of expansion and contraction feedback;

[0057] (2) The preparation method provided by the present invention avoids the problem of uneven force caused by the height difference of different plate thicknesses by introducing a buffer pressing material, thereby solving the risk of local pressure loss of the rigid-flexible composite plate blank due to uneven force. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1A schematic diagram of a pressing process provided in Example 1 of the present invention;

[0059] Among them, 1 is a buffer pressing material, and 2 is a rigid-flexible composite board blank. DETAILED DESCRIPTION

[0060] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0061] Example 1

[0062] This embodiment provides an ultra-high-rise rigid-flexible board with unequal thicknesses, and a method for preparing the ultra-high-rise rigid-flexible board with unequal thicknesses comprises the following steps:

[0063] (1) stacking a rigid board, a solid bonding board, a 25-layer flexible board, a solid bonding board, and a rigid board in sequence, and fixing them to obtain a rigid-flexible bonded board blank;

[0064] A layer of solid adhesive plate is respectively arranged between adjacent flexible plates;

[0065] (2) Figure 1 As shown, the buffer pressing material 1, the rigid-flexible board blank 2 and the buffer pressing material 1 are stacked in sequence, and the rigid-flexible board is obtained after the pressing process;

[0066] The wire width accuracy tolerance of the flexible board and the rigid board is 2.1%;

[0067] The lamination process was performed at a temperature of 220°C, a time of 3 hours, and a pressure of 30 kg / cm 2 ;

[0068] (3) performing drilling, solder masking, surface treatment, testing and analysis, and milling on the rigid-flexible board described in step (2);

[0069] The surface treatment includes a nickel immersion treatment and a gold immersion treatment performed sequentially, wherein the thickness of the nickel layer in the nickel immersion treatment is 4 μm, and the thickness of the gold layer in the gold immersion treatment is 0.075 μm.

[0070] Example 2

[0071] This embodiment provides an ultra-high-rise rigid-flexible board with unequal thicknesses, and a method for preparing the ultra-high-rise rigid-flexible board with unequal thicknesses comprises the following steps:

[0072] (1) stacking a rigid board, a solid bonding board, 20 layers of flexible boards, a solid bonding board, and a rigid board in sequence, and fixing them to obtain a rigid-flexible bonded board blank;

[0073] A layer of solid adhesive plate is respectively arranged between adjacent flexible plates;

[0074] (2) stacking the buffer pressing material, the rigid-flexible board blank, and the buffer pressing material in order, and obtaining the rigid-flexible board after pressing;

[0075] The wire width accuracy tolerance of the flexible board and the rigid board is 10%;

[0076] The temperature of the pressing process is 200°C, the time is 3.5 hours, and the pressure is 25 kg / cm 2 ;

[0077] (3) performing drilling, solder masking, surface treatment, testing and analysis, and milling on the rigid-flexible board described in step (2);

[0078] The surface treatment includes a nickel immersion treatment and a gold immersion treatment performed sequentially, wherein the thickness of the nickel layer in the nickel immersion treatment is 3 μm, and the thickness of the gold layer in the gold immersion treatment is 0.05 μm.

[0079] Example 3

[0080] This embodiment provides an ultra-high-rise rigid-flexible board with unequal thicknesses, and a method for preparing the ultra-high-rise rigid-flexible board with unequal thicknesses comprises the following steps:

[0081] (1) stacking a rigid board, a solid bonding board, a 26-layer flexible board, a solid bonding board, and a rigid board in sequence, and fixing them to obtain a rigid-flexible bonded board blank;

[0082] A layer of solid adhesive plate is respectively arranged between adjacent flexible plates;

[0083] (2) stacking the buffer pressing material, the rigid-flexible board blank, and the buffer pressing material in order, and obtaining the rigid-flexible board after pressing;

[0084] The wire width accuracy tolerance of the flexible board and the rigid board is 5%;

[0085] The lamination process was performed at a temperature of 210°C, a time of 2.5 hours, and a pressure of 35 kg / cm 2 ;

[0086] (3) performing drilling, solder masking, surface treatment, testing and analysis, and milling on the rigid-flexible board described in step (2);

[0087] The surface treatment includes a nickel immersion treatment and a gold immersion treatment performed sequentially, wherein the thickness of the nickel layer in the nickel immersion treatment is 5 μm, and the thickness of the gold layer in the gold immersion treatment is 0.1 μm.

[0088] Example 4

[0089] This embodiment provides an ultra-high-rise rigid-flexible board with unequal thicknesses. The method for preparing the ultra-high-rise rigid-flexible board with unequal thicknesses is different from that of Embodiment 1 only in that:

[0090] In this embodiment, the temperature of the pressing process in step (2) is adjusted to 190°C.

[0091] Example 5

[0092] This embodiment provides an ultra-high-rise rigid-flexible board with unequal thicknesses. The method for preparing the ultra-high-rise rigid-flexible board with unequal thicknesses is different from that of Embodiment 1 only in that:

[0093] In this embodiment, the temperature of the pressing process in step (2) is adjusted to 250°C.

[0094] Example 6

[0095] This embodiment provides an ultra-high-rise rigid-flexible board with unequal thicknesses. The method for preparing the ultra-high-rise rigid-flexible board with unequal thicknesses is different from that of Embodiment 1 only in that:

[0096] In this embodiment, the pressure of the pressing process in step (2) is adjusted to 20 kg / cm 2 .

[0097] Example 7

[0098] This embodiment provides an ultra-high-rise rigid-flexible board with unequal thicknesses. The method for preparing the ultra-high-rise rigid-flexible board with unequal thicknesses is different from that of Embodiment 1 only in that:

[0099] In this embodiment, the pressure of the pressing process in step (2) is adjusted to 40 kg / cm 2 .

[0100] Comparative Example 1

[0101] This embodiment provides an ultra-high-rise rigid-flexible board with unequal thicknesses. The method for preparing the ultra-high-rise rigid-flexible board with unequal thicknesses is different from that of Embodiment 1 only in that:

[0102] In this comparative example, the wire width precision tolerance of the flexible board and the rigid board in step (2) is adjusted to 15%.

[0103] Comparative Example 2

[0104] This embodiment provides an ultra-high-rise rigid-flexible board with unequal thicknesses. The method for preparing the ultra-high-rise rigid-flexible board with unequal thicknesses is different from that of Embodiment 1 only in that:

[0105] In this comparative example, step (2) is adjusted as follows: stacking the buffer pressing material and the rigid-flexible board blank in sequence, that is, omitting the buffer pressing material on one side of the rigid-flexible board blank.

[0106] Comparative Example 3

[0107] This embodiment provides an ultra-high-rise rigid-flexible board with unequal thicknesses. The method for preparing the ultra-high-rise rigid-flexible board with unequal thicknesses is different from that of Embodiment 1 only in that:

[0108] In this comparative example, the stacking of buffer pressing materials described in step (2) is omitted, that is, the rigid-flexible composite board blank is directly pressed.

[0109] The circuit conductivity and stability of the ultra-high-layer unequal-thickness rigid-flex boards provided in the above embodiments and comparative examples were tested, and the results are shown in Table 1.

[0110] Wherein, the circuit conductivity detection includes: flying probe test, multimeter test, etc.

[0111] The stability test includes: heat shock resistance test, moisture resistance test, aging test, etc., to determine whether the rigid-flex board has cracks and delamination.

[0112] Table 1

[0113] Is it powered? Whether there are cracks and delamination Example 1 power ups No cracks and delamination Example 2 power ups No cracks and delamination Example 3 power ups No cracks and delamination Example 4 No electricity No cracks, but delamination between layers Example 5 Power is on, but the resistance is too high There are interlayer cracks, no delamination Example 6 No electricity No cracks, but delamination between layers Example 7 Power is on, but the resistance is too high There are interlayer cracks, no delamination Comparative Example 1 Power is on, but the resistance is too small No cracks and delamination Comparative Example 2 No electricity No cracks, but delamination between layers Comparative Example 3 No electricity No cracks, but delamination between layers

[0114] According to Table 1, we can know the following points:

[0115] (1) Comprehensive analysis of Examples 1-3 shows that the rigid-flexible board obtained by the preparation method provided by the present invention has excellent stability, avoids the problem of lamination deviation that may exist during the lamination process, and improves the inter-layer alignment accuracy;

[0116] (2) Comprehensive analysis of Example 1 and Examples 4-7 shows that the selection of the lamination temperature or the lamination pressure during the lamination process will affect the stability or circuit conductivity of the rigid-flexible board;

[0117] When the lamination temperature is too high during the lamination process, the resin and other materials in the PCB substrate will be over-cured, the molecular structure will change, and the substrate will become hard and brittle. High temperature will also change the insulating material on the PCB board, resulting in a decrease in insulation resistance and changes in line impedance, which will affect electrical performance; when the lamination temperature is too low, the resin will not be fully cured and the interlayer bonding will be poor. Incompletely cured resin may soften in a high temperature environment and cause the PCB board to deform, which will not only reduce the mechanical strength and heat resistance of the PCB, but also affect the installation and normal use of electronic components.

[0118] When the lamination pressure is too high during the lamination process, the substrate will be deformed, the internal structure of the material will be damaged, the insulation layer will become thinner or local defects will appear. Excessive pressure will change the physical size and shape of the circuit on the PCB board, thereby affecting the impedance of the circuit. When the lamination pressure is too low, it will cause delamination, voids and bubbles between layers. Due to low pressure, the material resin is not fully cured, the dielectric constant and thickness of the PCB board are uneven, which will cause changes in the line impedance, affect the transmission quality of the signal, and cause problems such as signal reflection and attenuation.

[0119] (3) Comprehensive analysis of Example 1 and Comparative Example 1 shows that the larger tolerance of the wire width accuracy of the flexible board and the rigid board directly leads to the problem of lamination displacement during the lamination process, thereby affecting the stability and circuit conductivity of the rigid-flexible board;

[0120] (4) Comprehensive analysis of Example 1 and Comparative Examples 2-3 shows that the use of the buffer pressing material can avoid the problem of uneven force caused by the height difference of different plate thicknesses;

[0121] When the use of buffer pressing materials is omitted or reduced, it will cause the pressure acting on the surface of the rigid-flexible board to be unbalanced, which will lead to local pressure loss of the rigid-flexible board and affect the stability of the rigid-flexible board.

[0122] To sum up, the preparation method provided by the present invention improves the problem of lamination displacement caused by material expansion and contraction after core plate processing through a processing method of expansion and contraction feedback; in addition, the use of buffering pressing materials avoids the problem of uneven force caused by the height difference of different plate thicknesses, thereby solving the risk of local pressure loss caused by uneven force.

[0123] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing an ultra-high-rise rigid-flex board with unequal thickness, characterized in that: The preparation method comprises the following steps: (1) stacking a rigid board, a solid bonding board, at least 20 layers of flexible boards, a solid bonding board, and a rigid board in sequence, and fixing them to obtain a rigid-flexible bonded board blank; (2) stacking the buffer pressing material, the rigid-flexible board blank, and the buffer pressing material in order, and obtaining the rigid-flexible board after pressing; The wire width accuracy tolerance of the flexible board and the rigid board is ±10%.

2. The preparation method according to claim 1, characterized in that: The calculation formula for the wire width accuracy tolerance of the flexible board and the rigid board is: (The wire width of the flexible board - the wire width of the rigid board) / the wire width of the flexible board×100%.

3. The preparation method according to claim 1 or 2, characterized in that: A layer of solid adhesive plate is respectively arranged between adjacent flexible plates; Preferably, the buffer lamination material in step (2) comprises a prepreg.

4. The preparation method according to any one of claims 1 to 3, characterized in that The temperature of the pressing treatment in step (2) is 200-220° C. Preferably, the pressing treatment time in step (2) is 2.5 to 3.5 hours.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The pressure of the pressing process in step (2) is 25-35 kg / cm 2 .

6. The preparation method according to any one of claims 1 to 5, characterized in that: The pressing process in step (2) also includes drilling, solder masking, surface treatment, testing and analysis, and milling.

7. The preparation method according to claim 6, characterized in that: The surface treatment includes nickel immersion treatment and gold immersion treatment performed in sequence; Preferably, the thickness of the nickel layer in the nickel deposition process is 3 to 5 μm; Preferably, the thickness of the gold layer in the gold immersion process is 0.05-0.1 μm.

8. The preparation method according to claim 6, characterized in that: The test analysis is used to test the connectivity and insulation of the rigid-flex board.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: (1) stacking a rigid board, a solid bonding board, at least 20 layers of flexible boards, a solid bonding board, and a rigid board in sequence, and fixing them to obtain a rigid-flexible bonded board blank; A layer of solid adhesive plate is respectively arranged between adjacent flexible plates; (2) stacking the buffer pressing material, the rigid-flexible board blank, and the buffer pressing material in order, and obtaining the rigid-flexible board after pressing; The wire width accuracy tolerance of the flexible board and the rigid board is ±10%; The temperature of the pressing treatment is 200-220°C, the time is 2.5-3.5 hours, and the pressure is 25-35 kg / cm 2 ; (3) performing drilling, solder masking, surface treatment, testing and analysis, and milling on the rigid-flexible board described in step (2); The surface treatment includes nickel immersion treatment and gold immersion treatment performed in sequence. The thickness of the nickel layer in the nickel immersion treatment is 3-5 μm, and the thickness of the gold layer in the gold immersion treatment is 0.05-0.1 μm.

10. An ultra-high-rise unequal thickness rigid-flex board, characterized in that: The ultra-high-rise unequal-thickness rigid-flexible board is obtained by the preparation method described in any one of claims 1 to 9.

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