Printed circuit board and preparation method thereof

Abstract

The invention discloses a printed circuit board and a preparation method thereof. The printed circuit board comprises a core board, a first insulating layer, a second insulating layer, a first insulating layer and a second insulating layer, the signal layer and the power supply layer are arranged on the same layer at intervals, and the thickness of the power supply layer is larger than that of the signal layer in the first direction; the signal layer is located in the central area of the core board. The power layers are located on two sides of the signal layer. A blind slot with a metalized side wall is arranged between the signal layer and the power supply layer, and the blind slot with the metalized side wall is used for isolating the signal layer from the power supply layer; a through hole with a metalized side wall is formed in the middle position of the central area of the core plate, and the through hole penetrates through the first composition plate, the second composition plate and the at least one core plate. According to the invention, the cost can be reduced and the integrity of signal transmission is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of printed circuit boards, and in particular to a printed circuit board and a preparation method thereof. Background Art

[0002] In order to improve the wiring density of the signal layer of the server printed circuit board (PCB) and effectively power the components, the signal layer and power layer lines are usually realized by local acid etching and copper reduction based on the pattern transfer of thick copper core boards above 2OZ, which leads to resource waste, operating costs and environmental problems, which is contrary to the sustainable development goals of the industry's environmental, social and corporate governance (ESG). Summary of the invention

[0003] The present invention provides a printed circuit board and a preparation method thereof, which can reduce costs and ensure the integrity of signal transmission.

[0004] According to one aspect of the present invention, there is provided a printed circuit board, comprising:

[0005] A first composite panel, a second composite panel and at least one core panel; the at least one core panel is located between the first composite panel and the second composite panel;

[0006] The core board includes a shielding layer, a first prepreg, a signal layer and a power layer; the first prepreg is located on a side of the shielding layer away from the first composite board; the signal layer is located on a side of the first prepreg away from the shielding layer, the signal layer and the power layer are in the same layer and are arranged at intervals, and along the first direction, the thickness of the power layer is greater than that of the signal layer; the signal layer is located in the central area of ​​the core board, and the power layer is located on both sides of the signal layer; wherein the first direction is the direction from the first composite board to the second composite board;

[0007] A blind groove with metallized sidewalls is provided between the signal layer and the power layer, and the blind groove with metallized sidewalls is used to isolate the signal layer and the power layer;

[0008] A through hole with metalized sidewalls is arranged in the middle of the central area of ​​the core board, and the through hole passes through the first combined board, the second combined board and at least one core board.

[0009] Optionally, at least one core plate includes a first core plate and a second core plate; the second core plate is located on a side of the first core plate away from the first composite plate;

[0010] A second prepreg is arranged between the first core board and the second core board, the second prepreg covers the signal layer, the power layer and a part of the first prepreg of the first core board, and contacts with the shielding layer of the second core board;

[0011] The blind groove of the side wall metallization includes a first blind groove and a second blind groove; the first blind groove is located between the signal layer and the power layer of the first core board, and the first blind groove penetrates from the surface of the first combination board away from the second combination board to be flush with the surface of the power layer of the first core board away from the first combination board; the second blind groove is located between the signal layer and the power layer of the second core board, and the second blind groove penetrates from the surface of the second combination board away from the first combination board to be flush with the surface of the signal layer of the second core board away from the second combination board.

[0012] Optionally, the first composite board includes a plurality of first sub-boards stacked together, each of the first sub-boards includes a first metal layer and a third prepreg, and the first metal layer is located on a side of the third prepreg away from the core board;

[0013] The second composite board includes a plurality of second sub-boards stacked in layers, each of the second sub-boards includes a second metal layer and a fourth prepreg, and the second metal layer is located on a side of the fourth prepreg away from the core board;

[0014] Along the first direction, odd-numbered metal layers are signal layers, and even-numbered metal layers are shielding layers.

[0015] Optionally, along the first direction, the thickness of the signal layer is less than the thickness of the shielding layer.

[0016] Optionally, the printed circuit board also includes:

[0017] Metal block, the metal block is located inside the blind groove.

[0018] Optionally, the power layer includes a third metal layer and a fourth metal layer, the fourth metal layer is located on a side of the third metal layer away from the first prepreg; the third metal layer has the same thickness as the signal layer of the core board.

[0019] Optionally, along the second direction, the distance between the power layer of the core board and the signal layer of the core board is greater than or equal to 3 mil; wherein the second direction intersects the first direction. Optionally, along the first direction, the thickness of the power layer is greater than or equal to 4 oz;

[0020] Along the first direction, the thickness of the first prepreg is greater than or equal to 4 mil.

[0021] According to another aspect of the present invention, there is provided a method for preparing a printed circuit board, comprising:

[0022] At least one core board is formed; the core board comprises a shielding layer, a first prepreg, a signal layer and a power layer; the signal layer is located on a side of the first prepreg away from the shielding layer, the signal layer and the power layer are in the same layer and are arranged at intervals, and along the first direction, the thickness of the power layer is greater than that of the signal layer; the signal layer is located in the central area of ​​the core board, and the power layer is located on both sides of the signal layer;

[0023] A first combined board and a second combined board are formed; the first prepreg is located on a side of the shielding layer away from the first combined board; wherein the first direction is the direction from the first combined board to the second combined board;

[0024] Pressing the first combined board, the second combined board and at least one core board;

[0025] A through hole is formed; the through hole is located in the middle of the central area of ​​the core plate, and the through hole passes through the first combined plate, the second combined plate and at least one core plate;

[0026] A blind groove is formed; the blind groove is located between the signal layer and the power layer;

[0027] forming a through hole with sidewall metallization;

[0028] A blind trench with metallized sidewalls is formed; the blind trench with metallized sidewalls is used to isolate the signal layer and the power layer.

[0029] Optionally, forming at least one core plate comprises:

[0030] Forming a shielding layer, a first prepreg, and a signal metal layer stacked in sequence;

[0031] forming a first dry film on a side of the signal metal layer away from the first prepreg;

[0032] patterning a first dry film;

[0033] The signal metal layer is etched through the patterned first dry film to form a signal layer and a third metal layer; the third metal layer has the same thickness as the signal layer of the core board;

[0034] removing the first dry film;

[0035] forming a second dry film on a side of the signal layer away from the first prepreg;

[0036] patterning the second dry film, wherein the second dry film exposes the third metal layer;

[0037] A fourth metal layer is formed on a side of the third metal layer away from the first prepreg; the third metal layer and the fourth metal layer are power supply layers.

[0038] The printed circuit board provided by the technical solution of the embodiment of the present invention comprises: a first composite board, a second composite board and at least one core board; at least one core board is located between the first composite board and the second composite board; the core board comprises a shielding layer, a first prepreg, a signal layer and a power layer; the first prepreg is located on a side of the shielding layer away from the first composite board; the signal layer is located on a side of the first prepreg away from the shielding layer, the signal layer and the power layer are in the same layer and are arranged at intervals, and along the first direction, the thickness of the power layer is greater than the thickness of the signal layer; the signal layer is located in the central area of ​​the core board, and the power layer is located on both sides of the signal layer; wherein the first direction is the direction from the first composite board to the second composite board; a blind groove with metallized side walls is provided between the signal layer and the power layer, and the blind groove with metallized side walls is used to isolate the signal layer and the power layer; a through hole with metallized side walls is provided in the middle position of the central area of ​​the core board, and the through hole passes through the first composite board, the second composite board and at least one core board. In the embodiment of the present invention, the signal layer and the power layer are arranged in the same layer and at intervals. Along the first direction, the thickness of the power layer is greater than the thickness of the signal layer; the cost can be reduced and the high-current power supply function of the PCB can be ensured not to be affected; a blind groove with metallized side walls is arranged between the signal layer and the power layer, so that the blind groove with metallized side walls can completely isolate the power layer and the signal layer, avoiding signal integrity problems such as crosstalk, reflection and electromagnetic interference between the power layer and the signal layer of the same layer, thereby ensuring the integrity of signal transmission.

[0039] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 It is a structural schematic diagram of a printed circuit board provided by an embodiment of the present invention.

[0042] Figure 2 It is a structural schematic diagram of a core board provided by an embodiment of the present invention.

[0043] Figure 3 The present invention provides a flowchart of a method for preparing a printed circuit board.

[0044] Figure 4 It is a schematic diagram of an intermediate structure of a printed circuit board provided by an embodiment of the present invention.

[0045] Figure 5 yes Figure 3 A detailed flow chart included in S110. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0047] It should be noted that the terms "first", "second", etc. in the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0048] An embodiment of the present invention provides a printed circuit board, Figure 1 is a schematic diagram of the structure of a printed circuit board provided by an embodiment of the present invention, Figure 2 is a schematic diagram of the structure of a core plate provided by an embodiment of the present invention, with reference to Figure 1 and Figure 2 , the printed circuit board includes:

[0049] A first combined board 100, a second combined board 200 and at least one core board 300; the at least one core board 300 is located between the first combined board 100 and the second combined board 200;

[0050] The core board 300 includes a shielding layer 31, a first prepreg 32, a signal layer 33 and a power layer 34; the first prepreg 32 is located on the side of the shielding layer 31 away from the first composite board 100; the signal layer 33 is located on the side of the first prepreg 32 away from the shielding layer 31, the signal layer 33 and the power layer 34 are in the same layer and are arranged at intervals, and along the first direction X, the thickness of the power layer 34 is greater than the thickness of the signal layer 33; the signal layer 33 is located in the central area of ​​the core board 300, and the power layer 34 is located on both sides of the signal layer 33; wherein the first direction X is the direction from the first composite board 100 to the second composite board 200;

[0051] A blind groove 35 with metallized side walls is provided between the signal layer 33 and the power layer 34, and the blind groove 35 with metallized side walls is used to isolate the signal layer 33 and the power layer 34; a through hole 36 with metallized side walls is provided in the middle position of the central area of ​​the core board 300, and the through hole 36 passes through the first combined board 100, the second combined board 200 and at least one core board 300.

[0052] Among them, the first combination board 100 and the second combination board 200 are both multi-layer boards, and the first combination board 100 and the second combination board 200 can both transmit signals and perform crosstalk shielding; the signal layer 33 is used to transmit signals, and the shielding layer 31 is a grounding layer for shielding interference; the thickness of the signal layer 33 and the shielding layer 31 are different, and the thickness of the shielding layer 31 can be set to be greater than the thickness of the signal layer 33, so that the shielding effect of the shielding layer 31 can be better, thereby ensuring the integrity of signal transmission.

[0053] The signal layer 33 and the power layer 34 are arranged on the same layer, which can improve the wiring density of the printed circuit board for effective power supply. Along the first direction X, the thickness of the power layer 34 is greater than that of the signal layer 33, and the thickness of the power layer 34 can be greater than 4OZ, thereby ensuring high current power supply. Exemplarily, the material of the signal layer 33 and the power layer 34 can be a copper layer. A dense signal line can be produced by forming a thin signal layer on the first semi-cured sheet 32 ​​and performing local acid etching, and then a thick power layer 34 is produced by a semi-additive method at the position of the power layer 34 on the same layer. The process design can avoid wasting copper materials, reduce costs, and control the overall graphic etching factor to meet the standard while ensuring that the high current power supply function of the PCB is not affected.

[0054] Due to the signal integrity problems such as crosstalk, reflection and electromagnetic interference between the power layer 34 and the signal layer 33 of the same layer during high-speed signal transmission, a blind groove 35 with metallized sidewalls is provided between the signal layer 33 and the power layer 34. For example, along the second direction Y, the blind groove 35 with metallized sidewalls penetrating the first composite board 100 can be penetrated from the surface of the first composite board 100 away from the second composite board 200 to be flush with the surface of the power layer 34 away from the first composite board 100; the blind groove 35 with metallized sidewalls penetrating the second composite board 200 can be penetrated from the surface of the second composite board 200 away from the first composite board 100 to be flush with the surface of the signal layer 33 away from the second composite board 200; the blind groove 35 with metallized sidewalls completely isolates the power layer 34 from the signal layer 33, avoids signal integrity problems such as crosstalk, reflection and electromagnetic interference between the power layer 34 and the signal layer 33 of the same layer, and ensures the integrity of signal transmission. A through hole 36 with sidewall metallization is provided in the middle position of the central area of ​​the core board 300. The through hole 36 passes through the first combined board 100, the second combined board 200 and at least one core board 300, so that the signals of the first combined board 100, the second combined board 200 and at least one core board 300 can be electrically interconnected through the through hole 36 with sidewall metallization.

[0055] The printed circuit board provided by the technical solution of the embodiment of the present invention includes: a first combined board 100, a second combined board 200 and at least one core board 300; at least one core board 300 is located between the first combined board 100 and the second combined board 200; the core board 300 includes a shielding layer 31, a first prepreg 32, a signal layer 33 and a power layer 34; the first prepreg 32 is located on the side of the shielding layer 31 away from the first combined board 100; the signal layer 33 is located on the side of the first prepreg 32 away from the shielding layer 31, the signal layer 33 and the power layer 34 are in the same layer and are arranged at intervals, and along the first direction X, the power layer The thickness of the core board 300 is greater than that of the signal layer 34; the signal layer 33 is located in the central area of ​​the core board 300, and the power layer 34 is located on both sides of the signal layer 33; wherein the first direction X is the direction from the first combination board 100 to the second combination board 200; a blind groove 35 with metallized side walls is provided between the signal layer 33 and the power layer 34, and the blind groove 35 with metallized side walls is used to isolate the signal layer 33 and the power layer 34; a through hole 36 with metallized side walls is provided in the middle position of the central area of ​​the core board 300, and the through hole 36 passes through the first combination board 100, the second combination board 200 and at least one core board 300. In the embodiment of the present invention, the signal layer 33 and the power layer 34 are arranged in the same layer and at intervals. Along the first direction X, the thickness of the power layer 34 is greater than that of the signal layer 33. This can reduce costs and ensure that the high-current power supply function of the PCB is not affected. A blind groove 35 with metallized side walls is provided between the signal layer 33 and the power layer 34, so that the blind groove 35 with metallized side walls can completely isolate the power layer 34 and the signal layer 33, avoiding signal integrity problems such as crosstalk, reflection and electromagnetic interference between the power layer 34 and the signal layer 33 of the same layer, thereby ensuring the integrity of signal transmission.

[0056] Optional, reference Figure 1 , at least one core board 300 includes a first core board 301 and a second core board 302; the second core board 302 is located on a side of the first core board 301 away from the first composite board 100; a second prepreg 40 is arranged between the first core board 301 and the second core board 302, the second prepreg 40 covers the signal layer 33, the power layer 34 and a part of the first prepreg 32 of the first core board 301, and contacts with the shielding layer 31 of the second core board 302; the blind groove 35 of the side wall metallization includes a first blind groove 351 and a second blind groove 352; the first blind groove 3 51 is located between the signal layer 33 and the power layer 34 of the first core board 301, and the first blind groove 351 penetrates from the surface of the first combination board 100 away from the second combination board 200 to be flush with the surface of the power layer 34 of the first core board 301 away from the first combination board 100; the second blind groove 352 is located between the signal layer 33 and the power layer 34 of the second core board 302, and the second blind groove 352 penetrates from the surface of the second combination board 200 away from the first combination board 100 to be flush with the surface of the signal layer 33 of the second core board 302 away from the second combination board 200.

[0057] The first core plate 301 and the second core plate 302 are alternately pre-stacked by PIN-LAM and then pressed together. The first core plate 301 and the second core plate 302 can be fixed by PIN pins first and then pressed together. Figure 1 As shown; the second core board 302 is located on the side of the first core board 301 away from the first combination board 100; the printed circuit board includes the first core board 301 and the second core board 302, and the two core boards can provide better signal isolation and reduce crosstalk between signals; it can also accommodate more wiring lines, improve wiring density and signal layer number. The first blind groove 351 runs through the surface of the first combination board 100 away from the second combination board 200 to be flush with the surface of the power layer 34 of the first core board 301 away from the first combination board 100; the second blind groove 352 runs through the surface of the second combination board 200 away from the first combination board 100 to be flush with the surface of the signal layer 33 of the second core board 302 away from the second combination board 200, so that the blind groove 35 with metallized sidewalls completely isolates the power layer 34 and the signal layer 33, avoids signal integrity problems such as crosstalk, reflection and electromagnetic interference between the power layer 34 and the same layer signal layer 33, and ensures the integrity of signal transmission.

[0058] Optional, reference Figure 1 The first composite board 100 includes a plurality of first sub-boards 10 stacked together, each of the first sub-boards 10 includes a first metal layer 11 and a third semi-cured sheet 12, and the first metal layer 11 is located on a side of the third semi-cured sheet 12 away from the core board 300; the second composite board 200 includes a plurality of second sub-boards 20 stacked together, each of the second sub-boards 20 includes a second metal layer 21 and a fourth semi-cured sheet 22, and the second metal layer 21 is located on a side of the fourth semi-cured sheet 22 away from the core board 300; along the first direction X, the odd-numbered metal layers are signal layers, and the even-numbered metal layers are shielding layers.

[0059] in, Figure 1 There are 20 layers of boards from L1 to L20, L1 is the first layer, and so on, the odd-numbered metal layers are signal layers, and exemplary, L1, L3, L5, L7, L9, L11, L13, L15, L17 and L19 are signal layers, and the even-numbered metal layers are shielding layers, and exemplary, L2, L4, L6, L8, L10, L12, L14, L16, L18 and L20 are shielding layers for shielding crosstalk and electromagnetic interference of other signal layers to ensure the integrity of signal transmission; L1 and L20 can adopt 17μm reverse-treated electrolytic copper foil (RTF), which is a copper foil with different degrees of roughening on both sides of the copper foil, which can simultaneously enhance the peeling strength of both sides of the copper foil, making it easier to be bonded with the semi-cured sheet (Pre-Preg, PP) and dry film as an intermediate layer.

[0060] Optionally, along the first direction, the thickness of the signal layer is less than the thickness of the shielding layer.

[0061] Among them, the thickness of the signal layer is less than that of the shielding layer. The thicker the shielding layer is, the better it can avoid crosstalk, reflection and electromagnetic interference between signals; the thinner the signal layer is, the more effectively it can control impedance and insertion loss for signal transmission. For example, the thickness of the signal layer can be 1OZ, and the thickness of the shielding layer can be 2OZ.

[0062] Optionally, the printed circuit board further includes: a metal block, and the metal block is located inside the blind groove.

[0063] The metal block may be a copper block, and the blind groove with metallized sidewalls may be tightly fitted with the metal block to achieve a local heat dissipation effect, thereby also effectively controlling process heat dissipation and PCB operating temperature.

[0064] Optional, reference Figure 2 The power layer 34 includes a third metal layer 01 and a fourth metal layer 02 . The fourth metal layer 02 is located on a side of the third metal layer 01 away from the first prepreg 32 . The third metal layer 01 has the same thickness as the signal layer 33 of the core board 300 .

[0065] The third metal layer 01 and the signal layer 33 of the core board 300 are formed simultaneously by the same preparation method and the same material, so the third metal layer 01 and the signal layer 33 of the core board 300 have the same thickness, and the fourth metal layer 02 is formed by electroplating. Exemplarily, the signal layer 33 may be 1OZ thick, and the power layer 34 may be 4OZ thick.

[0066] Optionally, along the second direction, the distance between the power layer of the core board and the signal layer of the core board is greater than or equal to 3 mil; wherein the second direction intersects with the first direction.

[0067] Among them, the distance between the power layer of the core board and the signal layer of the core board is greater than or equal to 3 mils, which can reduce the crosstalk, reflection and electromagnetic interference between the power layer of the core board and the signal layer of the core board, and can facilitate the subsequent formation of blind grooves with side wall metallization to ensure the integrity of signal transmission.

[0068] Optionally, along the first direction, the thickness of the power supply layer is greater than or equal to 4OZ; along the first direction, the thickness of the first prepreg is greater than or equal to 4mil.

[0069] Among them, the thickness of the power layer is greater than or equal to 4OZ; illustratively, the thickness of the power layer is equal to 4OZ, so as to ensure high current power supply; the thickness of the first semi-cured sheet is greater than or equal to 4mil, which can provide better support and bonding to prevent delamination.

[0070] The embodiment of the present invention provides a method for preparing a printed circuit board based on the above embodiment, which is used to prepare the printed circuit board described in any embodiment of the present invention. Figure 3 is a flow chart of a method for preparing a printed circuit board provided by an embodiment of the present invention, Figure 4 is a schematic diagram of the intermediate structure of a printed circuit board provided by an embodiment of the present invention, with reference to Figure 3 and Figure 4 , the preparation method comprises:

[0071] S110, forming at least one core board; the core board includes a shielding layer, a first prepreg, a signal layer and a power layer; the signal layer is located on a side of the first prepreg away from the shielding layer, the signal layer and the power layer are on the same layer and are spaced apart, and along the first direction, the thickness of the power layer is greater than the thickness of the signal layer; the signal layer is located in the central area of ​​the core board, and the power layer is located on both sides of the signal layer.

[0072] The first composite board includes a plurality of first sub-boards stacked together, each of which includes a first metal layer and a third semi-cured sheet, and the first metal layer is located on a side of the third semi-cured sheet away from the core board; the second composite board includes a plurality of second sub-boards stacked together, each of which includes a second metal layer and a fourth semi-cured sheet, and the second metal layer is located on a side of the fourth semi-cured sheet away from the core board; along the first direction, the odd-numbered metal layers are signal layers, and the even-numbered metal layers are shielding layers.

[0073] S120, forming a first combined board and a second combined board; the first prepreg is located on a side of the shielding layer away from the first combined board; wherein the first direction is a direction from the first combined board to the second combined board.

[0074] S130, pressing the first combined board, the second combined board and at least one core board together.

[0075] S140, forming a through hole; the through hole is located in the middle of the central area of ​​the core board, and the through hole passes through the first combined board, the second combined board and at least one core board.

[0076] S150, forming a blind groove; the blind groove is located between the signal layer and the power layer.

[0077] Among them, at least one core board may include a first core board and a second core board; the second core board is located on a side of the first core board away from the first combination board; a second semi-cured sheet is arranged between the first core board and the second core board, the second semi-cured sheet covers the signal layer, the power layer and part of the first semi-cured sheet of the first core board, and contacts with the shielding layer of the second core board; the blind groove of the side wall metallization includes a first blind groove and a second blind groove; the first blind groove is located between the signal layer and the power layer of the first core board, the first blind groove passes through the surface of the first combination board away from the second combination board to be flush with the surface of the power layer of the first core board away from the first combination board; the second blind groove is located between the signal layer and the power layer of the second core board, the second blind groove passes through the surface of the second combination board away from the first combination board to be flush with the surface of the signal layer of the second core board away from the second combination board.

[0078] S160 , forming a through hole with metallized sidewalls.

[0079] S170, forming a blind groove with metallized sidewalls; the blind groove with metallized sidewalls is used to isolate the signal layer and the power layer.

[0080] In the embodiment of the present invention, after forming the first composite board, the second composite board and at least one core board, the first composite board, the second composite board and at least one core board are pressed together, and the copper surface is controlled by the copper reduction process to ensure that the etching factor of the outer layer circuit meets the standard. Figure 4 After the structure in, a through hole is formed by mechanical drilling, and a blind groove is formed by controlled depth milling; the third dry film is used to cover the blind groove, and the first pattern electroplating is used to form a through hole with metallized sidewall, and the metal thickness of the side wall of the through hole is 0.8mil-1.0mil; the third dry film is removed, and then the hole inspection is carried out to detect the metal quality of the side wall of the through hole; the through hole is covered with a fourth dry film, and the second pattern electroplating is used to form a blind groove with metallized sidewall, and the metal thickness of the side wall of the blind groove is 4.8mil-5mil; the fourth dry film is removed, and then the groove inspection is carried out to detect the metal quality of the side wall of the blind groove; the fifth dry film is used to cover the required outer layer circuit pattern to form the outer layer circuit, and then automatic optical inspection and manual maintenance (AOI&VRS) are carried out.

[0081] Optional, Figure 5 yes Figure 3 A detailed flow chart included in S110, refer to Figure 5 , S110, forming at least one core board, comprising:

[0082] S111, forming a shielding layer, a first prepreg, and a signal metal layer stacked in sequence;

[0083] S112, forming a first dry film on a side of the signal metal layer away from the first prepreg;

[0084] S113, patterning the first dry film;

[0085] S114, etching the signal metal layer through the patterned first dry film to form a signal layer and a third metal layer; the third metal layer has the same thickness as the signal layer of the core board;

[0086] S115, removing the first dry film;

[0087] S116, forming a second dry film on a side of the signal layer away from the first prepreg;

[0088] S117, patterning the second dry film, wherein the second dry film exposes the third metal layer;

[0089] S118, forming a fourth metal layer on a side of the third metal layer away from the first prepreg; the third metal layer and the fourth metal layer are power supply layers.

[0090] Among them, a shielding layer, a first semi-cured sheet and a signal metal layer are formed which are stacked in sequence, the thickness of the signal layer material layer is 1OZ, and a graphic first dry film is used to cover the signal metal layer, and the thickness of the first dry film is 1mil-1.2mil; the inner layer is acid-etched to form a third metal layer of the signal line and the power layer, and the first dry film is removed to perform automatic optical inspection (AOI) of the inner layer; the signal layer is protected by a graphic second dry film to expose the third metal layer, and the thickness of the second dry film is 5mil-6mil; then, graphic electroplating is performed on the third metal layer to form a power layer, and the thickness of the electroplated fourth metal layer can be 4mil; the second dry film is removed, and then process quality control (IPQC) is performed.

[0091] After the first acid etching, considering that the prepreg and the dry film are the same polymer material, a thick photoresist layer can be directly exposed on the surface of the signal metal layer by hot pressing to protect the signal layer circuit, and the area of ​​the power layer can be exposed for electroplating and thickening; after setting the specific current density, electroplating time and waveform parameters, the power layer is electroplated to a thickness of 4OZ, and then the film is stripped to obtain a core board that merges the local thick copper power layer and the signal layer. By first performing local acid etching on the core board to make dense signal routing, and then using the semi-additive method to make 4OZ thick copper on the same power layer, the process design can control the overall graphic etching factor to meet the standard while ensuring that the high current power supply function of the PCB is not affected; by adopting the selective electroplating method to increase the copper thickness, the copper demand of the power core board can be effectively reduced and energy saving and cost reduction can be achieved. The preparation method provided by the technical solution of the embodiment of the present invention proposes a local thick copper process flow for the inner layer of the PCB. The local thick copper process flow refers to the power layer and the signal layer being arranged on the same layer and the thickness of the power layer being greater than the thickness of the signal layer, which can reduce the number of pressing plate layers and shorten the processing steps, thereby ensuring the function of the PCB's large current stable output components; the same-layer matching design of the signal layer and the power layer can be realized to ensure the integrity of the signal line transmission; the specific copper thickness of the power layer is formed, which can effectively control the process heat dissipation and the PCB operating temperature

[0092] The method for preparing a printed circuit board provided by the technical solution of the embodiment of the present invention has the same beneficial effects as the printed circuit board described in any embodiment of the present invention.

[0093] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0094] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A printed circuit board, characterized in that: include: a first composite panel, a second composite panel, and at least one core panel; The at least one core panel is located between the first combined panel and the second combined panel; The core board comprises a shielding layer, a first prepreg, a signal layer and a power layer; the first prepreg is located on a side of the shielding layer away from the first combined board; the signal layer is located on a side of the first prepreg away from the shielding layer, the signal layer and the power layer are in the same layer and are arranged at intervals, and along the first direction, the thickness of the power layer is greater than the thickness of the signal layer; the signal layer is located in the central area of ​​the core board, and the power layer is located on both sides of the signal layer; wherein the first direction is the direction from the first combined board to the second combined board; A blind groove with metallized sidewalls is provided between the signal layer and the power layer, and the blind groove with metallized sidewalls is used to isolate the signal layer from the power layer; A through hole with metalized sidewalls is provided in the middle of the central area of ​​the core board, and the through hole passes through the first combined board, the second combined board and the at least one core board.

2. The printed circuit board according to claim 1, characterized in that: The at least one core plate comprises a first core plate and a second core plate; the second core plate is located on a side of the first core plate away from the first combined plate; A second prepreg is arranged between the first core board and the second core board, the second prepreg covers the signal layer, the power layer and a part of the first prepreg of the first core board, and contacts with the shielding layer of the second core board; The sidewall metallized blind groove includes a first blind groove and a second blind groove; the first blind groove is located between the signal layer and the power layer of the first core board, and the first blind groove penetrates from the surface of the first combination board away from the second combination board to be flush with the surface of the power layer of the first core board away from the first combination board; the second blind groove is located between the signal layer and the power layer of the second core board, and the second blind groove penetrates from the surface of the second combination board away from the first combination board to be flush with the surface of the signal layer of the second core board away from the second combination board.

3. The printed circuit board according to claim 2, characterized in that: The first composite board includes a plurality of first sub-boards stacked in layers, each of the first sub-boards includes a first metal layer and a third prepreg, and the first metal layer is located on a side of the third prepreg away from the core board; The second composite board includes a plurality of second sub-boards stacked in layers, each second sub-board includes a second metal layer and a fourth prepreg, and the second metal layer is located on a side of the fourth prepreg away from the core board; Along the first direction, odd-numbered metal layers are signal layers, and even-numbered metal layers are shielding layers.

4. The printed circuit board according to claim 3, characterized in that: Along the first direction, the thickness of the signal layer is smaller than the thickness of the shielding layer.

5. The printed circuit board according to claim 1, characterized in that: Also includes: A metal block is located inside the blind groove.

6. The printed circuit board according to claim 1, characterized in that: The power supply layer includes a third metal layer and a fourth metal layer. The fourth metal layer is located on a side of the third metal layer away from the first prepreg. The third metal layer has the same thickness as the signal layer of the core board.

7. The printed circuit board according to claim 1, characterized in that: Along the second direction, the distance between the power layer of the core board and the signal layer of the core board is greater than or equal to 3 mil; wherein the second direction intersects with the first direction.

8. The printed circuit board according to claim 6, characterized in that: Along the first direction, the thickness of the power layer is greater than or equal to 4OZ; Along the first direction, the thickness of the first prepreg is greater than or equal to 4 mil.

9. A method for preparing a printed circuit board, characterized in that: include: At least one core board is formed; the core board comprises a shielding layer, a first prepreg, a signal layer and a power layer; the signal layer is located on a side of the first prepreg away from the shielding layer, the signal layer and the power layer are in the same layer and are arranged at intervals, and along a first direction, the thickness of the power layer is greater than the thickness of the signal layer; the signal layer is located in the central area of ​​the core board, and the power layer is located on both sides of the signal layer; A first combined board and a second combined board are formed; the first prepreg is located on a side of the shielding layer away from the first combined board; wherein the first direction is the direction from the first combined board to the second combined board; Pressing the first combined board, the second combined board and the at least one core board together; forming a through hole; the through hole is located in the middle of the central area of ​​the core plate, and the through hole passes through the first combined plate, the second combined plate and the at least one core plate; forming a blind groove; the blind groove is located between the signal layer and the power layer; forming a through hole with sidewall metallization; A blind groove with metallized sidewalls is formed; the blind groove with metallized sidewalls is used to isolate the signal layer and the power layer.

10. The method for preparing a printed circuit board according to claim 9, characterized in that: Forming at least one core panel, comprising: Forming a shielding layer, a first prepreg, and a signal metal layer stacked in sequence; forming a first dry film on a side of the signal metal layer away from the first prepreg; patterning the first dry film; The signal metal layer is etched through the patterned first dry film to form a signal layer and a third metal layer; the third metal layer has the same thickness as the signal layer of the core board; removing the first dry film; forming a second dry film on a side of the signal layer away from the first prepreg; patterning the second dry film, wherein the second dry film exposes the third metal layer; A fourth metal layer is formed on a side of the third metal layer away from the first prepreg; the third metal layer and the fourth metal layer are power supply layers.

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