Circuit board and preparation method thereof

Abstract

The invention discloses a circuit board and a preparation method thereof. The preparation method of the circuit board comprises the following steps: providing a dielectric layer, a first metal layer and a circuit board body; the dielectric layer comprises at least one through hole; the circuit board body comprises at least two metal layers and an insulating layer located between the two adjacent metal layers; the dielectric layer comprises a prepreg; sequentially laminating the circuit board body, the dielectric layer and the first metal layer; performing laser drilling at the position of the through hole to form a blind hole penetrating through the first metal layer and the dielectric layer; and electroplating a conductive layer in the blind hole to form the circuit board. According to the technical scheme, the conductive layer formed in the blind hole can have good conductive reliability, and the working performance of the circuit board is improved.

Description

Technical Field

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

[0002] With the development of economy, the area of ​​circuit boards is getting smaller and smaller, but the circuit components are getting denser and denser. Generally, circuit boards are stacked to reduce the occupied area, and blind holes are used to make the stacked circuit boards conductive.

[0003] Blind holes are usually prepared by laser technology. Since the laser itself has a low absorption rate for glass fiber, the dielectric layer between adjacent metal layers in the circuit board usually includes glass fiber material. Therefore, when blind holes are prepared by laser technology, glass fiber material will remain in the blind holes. In the subsequent thermal stress operation process, the coating in the blind holes will produce cracks at the position where the glass fiber material exists, affecting the conductivity and reliability of the blind holes, and thus affecting the working reliability of the circuit board. Summary of the invention

[0004] The invention provides a circuit board and a preparation method thereof, so that a conductive layer formed in a blind hole has good conductive reliability and the working performance of the circuit board is improved.

[0005] In a first aspect, the present invention provides a method for preparing a circuit board, comprising:

[0006] A dielectric layer, a first metal layer, and a circuit board body are provided; the dielectric layer comprises at least one through hole; the circuit board body comprises at least two metal layers and an insulating layer located between two adjacent metal layers; the dielectric layer comprises a prepreg;

[0007] Laminating the circuit board body, the dielectric layer and the first metal layer in sequence;

[0008] Performing laser drilling at the location of the through hole to form a blind hole penetrating the first metal layer and the dielectric layer;

[0009] A conductive layer is electroplated in the blind hole to form the circuit board.

[0010] Optionally, the aperture of the blind hole is a1, and the aperture of the through hole is a2;

[0011] Among them, a2-a1≥4mil.

[0012] Optionally, before laser drilling is performed at the location of the through hole, the method further includes:

[0013] The first metal layer away from the circuit board body is subjected to browning treatment.

[0014] Optionally, before laminating the circuit board body, the dielectric layer and the first metal layer in sequence, the method further includes:

[0015] The through holes are plugged with resin.

[0016] Optionally, the circuit board body is provided, including:

[0017] providing at least two layers of said metal layer;

[0018] Providing at least one insulating layer;

[0019] Alternately placing the metal layers and the insulating layers so that the insulating layer is located between two adjacent metal layers;

[0020] The metal layers and the insulating layers are laminated to form the circuit board body.

[0021] Optionally, after laminating the metal layers and the insulating layers, the method further includes:

[0022] Drilling the pressed metal layers and the insulating layers to form sub-through holes penetrating the metal layers and the insulating layers;

[0023] The sub-through hole is subjected to electroplating, plugging and polishing in sequence to form the circuit board body; the circuit board body includes at least one sub-through hole.

[0024] Optionally, in the thickness direction of the circuit board, the blind hole at least partially overlaps with the sub-via hole.

[0025] Optionally, the aperture of the blind hole is a1, and the aperture of the sub-conducting hole is A1;

[0026] Among them, a1<A1.

[0027] In a second aspect, the present invention provides a circuit board, which is manufactured using the method for manufacturing a circuit board described in the first aspect.

[0028] The technical solution provided by the present invention is to set a through hole in the dielectric layer so that when the dielectric layer includes a material that is not easily absorbed by the laser, the dielectric layer at the location of the through hole can be removed. After laminating the circuit board body, the dielectric layer and the first metal layer, the resin contained in the dielectric layer can flow to the through hole to fill the through hole. When the first metal layer and the dielectric layer overlapping the through hole are then laser drilled, since the location of the through hole in the dielectric layer only includes resin material, the laser has a high absorption rate for the resin material. Therefore, after laser drilling, the blind hole formed does not contain glass fiber and other materials that are not easily absorbed by the laser, and the blind hole has a high cleanliness. The conductive layer formed in the blind hole also has good conductive reliability, thereby improving the working performance of the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flowchart of a method for preparing a circuit board provided by an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of the structure of a process for preparing a circuit board provided by an embodiment of the present invention;

[0031] Figure 3 A flow chart of another method for preparing a circuit board provided by an embodiment of the present invention;

[0032] Figure 4 A flowchart of another method for preparing a circuit board provided by an embodiment of the present invention;

[0033] Figure 5 A schematic diagram of another process structure for preparing a circuit board provided by an embodiment of the present invention;

[0034] Figure 6 A schematic diagram of the structure of a circuit board provided by an embodiment of the present invention;

[0035] Figure 7 A schematic diagram of the structure of another process for preparing a circuit board provided by an embodiment of the present invention;

[0036] Figure 8 A flow chart of a method for preparing a circuit board body provided by an embodiment of the present invention;

[0037] Fig. 9 A schematic diagram of the structure of a process for preparing a circuit board body provided by an embodiment of the present invention;

[0038] Fig.10 A schematic diagram of another process structure for preparing a circuit board body provided by an embodiment of the present invention;

[0039] Fig.11 A schematic structural diagram of another circuit board provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0041] An embodiment of the present invention provides a method for preparing a circuit board. The method is suitable for preparing the circuit board provided by the embodiment of the present invention. Figure 1 A flowchart of a method for preparing a circuit board provided by an embodiment of the present invention, Figure 2A schematic diagram of a process structure for preparing a circuit board provided by an embodiment of the present invention is shown as follows: Figure 1 As shown, the method for preparing the circuit board includes:

[0042] S11, providing a dielectric layer, a first metal layer, and a circuit board body.

[0043] Among them, reference Figure 2 The dielectric layer 21 includes at least one through hole 210. The circuit board body 001 includes at least two metal layers 10 and an insulating layer 22 located between two adjacent metal layers 10.

[0044] Specifically, the dielectric layer 21 includes a prepreg, and the insulating layer 22 may also include a prepreg, which is composed of glass fiber and resin material. The resin material has good viscosity and has a certain fluidity under the action of heat. Glass fiber, also known as glass fiber, has good insulation, heat resistance, corrosion resistance and high mechanical strength. In this way, the prepreg can provide a certain support force for the metal layer on the premise that the metal layers on both sides of the prepreg are insulated from each other. The specific method of providing the dielectric layer 21 can be: provide a whole layer of prepreg, and use a drilling machine and other equipment to drill holes at the corresponding positions of the prepreg to form a dielectric layer 21 including a through hole 210. Among them, the position where the through hole 201 is located is a part of the blind hole formed subsequently. The metal layer 10 and the first metal layer 11 include electrical components, such as transistors, diodes, resistors, wires and pins, etc. The insulating layer 22 and the dielectric layer 21 can achieve mutual insulation between the circuits and / or devices on different metal layers 10, and prevent the circuits and / or devices on two adjacent metal layers 10 from being wrongly connected, resulting in abnormal operation.

[0045] It should be noted that the number of through holes 210 in the dielectric layer 21 can be set according to the preparation requirements of the circuit board. Figure 2 In the description, only the dielectric layer 21 includes one through hole 210. When the circuit board needs to be provided with multiple blind holes, multiple through holes corresponding to the blind holes can be provided in the dielectric layer 21, and the number of the through holes is not specifically limited here.

[0046] S12, laminating the circuit board body, the dielectric layer and the first metal layer in sequence.

[0047] Specifically, refer to Figure 2After the circuit board body 001, dielectric layer 21 and first metal layer 11 are sequentially placed and aligned, a laminating device is used to provide a certain pressure to the circuit board body 001, dielectric layer 21 and first metal layer 11 under certain temperature conditions, so that the circuit board body 001, dielectric layer 21 and first metal layer 11 are firmly attached. The resin in the dielectric layer 21 flows to the position of the through hole 210 under the action of temperature and pressure, and then fills the through hole 210. After the lamination is completed, the position of the through hole 210 only includes the resin.

[0048] It is understandable that when the dielectric layer 21 includes a prepreg, since the glass fiber has a certain hardness, the glass fiber will not be displaced under a certain temperature and a certain pressure, so after lamination, the through hole 210 only includes resin.

[0049] S13, performing laser drilling at the location of the through hole to form a blind hole penetrating the first metal layer and the dielectric layer.

[0050] Specifically, refer to Figure 2 , laser drilling is performed at the location of the through hole 210, that is, the aperture of the laser drilling is less than or equal to the aperture of the through hole 210, so that the resin material located in the through hole 210 can be completely absorbed by the laser, and no glass fiber is left in the formed blind hole 30, thereby improving the cleanliness of the blind hole 30 and preventing the residual glass fiber in the blind hole 30 from affecting the conductive layer formed subsequently.

[0051] In an alternative embodiment, reference Figure 2 The aperture of the blind hole 30 is a1, and the aperture of the through hole 210 is a2; wherein, a2-a1≥4mil.

[0052] Specifically, when the difference between the aperture a2 of the through hole 210 and the aperture a1 of the blind hole 30 is less than 4 mil, a small positional offset will occur when the circuit board body 001 is laminated with the dielectric layer 21 and the first metal layer 11, and a certain positional offset will also occur during laser drilling. This positional offset may cause the position of the laser laser in the dielectric layer 21 to shift to the area where the through hole 210 is located, thereby causing glass fiber to remain in the formed blind hole 30, affecting the conductivity reliability of the subsequent conductive layer. Therefore, by setting the difference between the aperture a2 of the through hole 210 and the aperture a1 of the blind hole 30 to be greater than or equal to 4 mil, even if there is a lamination deviation and a drilling deviation, it can still be ensured that the aperture of the laser drilling is located within the aperture of the through hole 210, so that the position where the laser is performed in the dielectric layer 21 only includes the resin material, and the laser has a good absorption rate for the resin material, so that no glass fiber remains in the blind hole 30 formed by laser drilling, the cleanliness of the blind hole 30 is maintained, and the preparation reliability of the subsequent conductive layer is improved.

[0053] S14. Electroplating a conductive layer in the blind hole to form a circuit board.

[0054] Specifically, a conductive layer is plated in the blind hole 30 using electroplating equipment. Since the blind hole 30 has a small aperture, in order to ensure the conductive reliability of the conductive layer, the conductive layer is usually plated in the entire blind hole 30, that is, the blind hole 30 is completely filled with conductive material to ensure the conductive reliability of the blind hole 30.

[0055] The technical solution of the present invention is to set a through hole in the dielectric layer so that when the dielectric layer includes a material that is not easily absorbed by the laser, the dielectric layer at the location of the through hole can be removed. After laminating the circuit board body, the dielectric layer and the first metal layer, the resin contained in the dielectric layer can flow to the through hole to fill the through hole. When the first metal layer and the dielectric layer overlapping the through hole are then laser drilled, since the location of the through hole in the dielectric layer only includes resin material, the laser has a high absorption rate for the resin material. Therefore, after laser drilling, the blind hole formed does not contain glass fiber and other materials that are not easily absorbed by the laser, and the blind hole has a high cleanliness. The conductive layer formed in the blind hole also has good conductive reliability, thereby improving the working performance of the circuit board.

[0056] On the basis of the above-mentioned embodiment, the embodiment of the present invention describes the situation before laser drilling is performed at the location of the through hole. Figure 3 A flowchart of another method for preparing a circuit board provided by an embodiment of the present invention, such as Figure 3 As shown, the method for preparing the circuit board includes:

[0057] S21, providing a dielectric layer, a first metal layer, and a circuit board body.

[0058] The dielectric layer includes at least one through hole. The circuit board body includes at least two inner metal layers and an insulating layer located between two adjacent metal layers. The dielectric layer includes a prepreg.

[0059] S22, laminating the circuit board body, the dielectric layer and the first metal layer in sequence.

[0060] S23, performing browning treatment on the first metal layer away from the circuit board body.

[0061] Specifically, refer to Figure 2 , a certain concentration of sulfuric acid, hydrogen peroxide and browning liquid can be used to brown the first metal layer, so that the browned first metal layer 11 can be absorbed by the laser of the subsequent laser drilling. When the blind hole 30 is subsequently prepared, in the thickness direction Z of the circuit board, the first metal layer 11 overlapping with the through hole 210 and the resin in the through hole 210 can be removed in sequence by laser to form the blind hole 30, thereby improving the preparation efficiency.

[0062] S24, performing laser drilling at the location of the through hole to form a blind hole penetrating the first metal layer and the dielectric layer.

[0063] S25. Electroplating a conductive layer in the blind hole to form a circuit board.

[0064] According to the technical solution of the embodiment of the present invention, after laminating the circuit board body, the dielectric layer and the first metal layer, the first metal layer is browned so that the first metal layer can be absorbed by the laser and then removed. In this way, when preparing the blind hole by laser drilling, the first metal layer at the location of the through hole and the resin inside the through hole can be removed in sequence. When the laser is irradiated to the metal layer in the circuit board body that is in contact with the dielectric layer, since the metal layer in the circuit board body has not been browned, the metal layer in the circuit board body will not be absorbed by the laser and removed. Therefore, the formed blind hole only passes through the first metal layer and the dielectric layer, and the materials in the blind hole are all absorbed by the laser, so that the blind hole has a higher cleanliness and improves the conductivity reliability of the conductive layer in the blind hole.

[0065] On the basis of the above-mentioned embodiment, the embodiment of the present invention describes the situation before the circuit board body, the dielectric layer and the first metal layer are sequentially laminated. Figure 4 A flowchart of another method for preparing a circuit board provided by an embodiment of the present invention, Figure 5 Another schematic diagram of the process structure of preparing a circuit board provided by an embodiment of the present invention is as follows: Figure 4 As shown, the method for preparing the circuit board includes:

[0066] S31, providing a dielectric layer, a first metal layer, and a circuit board body.

[0067] The dielectric layer includes at least one through hole. The circuit board body includes at least two inner metal layers and an insulating layer located between two adjacent metal layers. The dielectric layer includes a prepreg.

[0068] S32, plugging the through holes with resin.

[0069] Specifically, refer to Figure 5 After providing the dielectric layer 21 including the through hole 210, a plugging device can be used to fill the through hole 210 with resin, so that the area where the through hole 210 is located in the dielectric layer 21 only includes the resin. In this way, after laminating the circuit board body, the dielectric layer and the first metal layer, the area where the through hole 210 is located in the dielectric layer 21 is still filled with resin. When laser drilling is performed at the through hole 210, the resin can be absorbed by the laser, so that the formed blind hole 30 has better cleanliness, so as to improve the conductivity reliability of the conductive layer in the blind hole 30.

[0070] S33, laminating the circuit board body, the dielectric layer and the first metal layer in sequence.

[0071] Wherein, the dielectric layer at least includes resin.

[0072] S34, performing laser drilling at the location of the through hole to form a blind hole penetrating the first metal layer and the dielectric layer.

[0073] S35. Electroplating a conductive layer in the blind hole to form a circuit board.

[0074] The technical solution of the embodiment of the present invention is to plug the through holes in the dielectric layer with resin to ensure that the position where the through holes in the dielectric layer are located only includes resin material, so that when blind holes are subsequently prepared at the positions where the through holes are located, the resin material located at the through holes can be absorbed by the laser, thereby improving the cleanliness of the blind holes and preventing the glass fiber and other materials that are not easily absorbed by the laser from remaining in the blind holes, thereby affecting the subsequently formed conductive layer, thereby improving the working reliability of the circuit board.

[0075] Understandably, Figure 2 and Figure 5 Only one side of the circuit board body 001 is shown as a blind hole. Blind holes can also be prepared on two opposite sides of the circuit board body 001. Figure 6 A schematic diagram of the structure of a circuit board provided by an embodiment of the present invention, such as Figure 6 As shown, blind holes are provided on both sides of the opposite surfaces of the circuit board body 001. The method for preparing blind holes in the above embodiment can be adopted to first prepare blind holes on one side of the circuit board body and then prepare blind holes on the other side of the circuit board body to form a circuit board with blind holes on both sides.

[0076] It should be noted that, regardless of whether the blind hole is provided on one side of the circuit board body 001 or on both sides of the circuit board body 001, the above description is only based on the example of the blind hole penetrating one dielectric layer 21. In other optional embodiments, on the basis that the blind hole penetrates at least one dielectric layer and at least one first metal layer, and the number of the dielectric layer and the first metal layer 11 is the same, the number of the blind holes penetrating the dielectric layer and the first metal layer can be set according to actual needs. Figure 7 A schematic diagram of another process structure of preparing a circuit board provided by an embodiment of the present invention is as follows: Figure 7As shown, the circuit board includes two dielectric layers 21 and two first metal layers 11, and both dielectric layers 21 include through holes 210. In the thickness direction of the circuit board body, the through holes 210 in the two dielectric layers 21 overlap, so that after the circuit board body 001, the dielectric layer 21, the first metal layer 11, the dielectric layer 21 and the first metal layer 11 are placed in sequence and laminated, the dielectric layer 21 can isolate and insulate the two adjacent first metal layers 11, and the dielectric layer 21 can also isolate and insulate the adjacent first metal layer 11 and the metal layer 11. Then, the first metal layer 11 on the side away from the circuit board body 001 is browned so that the laser can remove the first metal layer 11 overlapping with the through hole 210 to expose the resin material in the through hole 210. After the resin material in the through hole 210 is removed by the laser, since the first metal layer 11 close to the circuit board body 001 has not been browned, the laser cannot remove the first metal layer 11 overlapping with the through hole 210. At this time, the first metal layer 11 away from the circuit board body 001 can be browned. At this time, the area overlapping with the through hole 210 in the first metal layer 11 close to the circuit board body 001 is exposed, and the first metal layer 11 in this area is browned. Then, the laser is used to absorb the first metal layer 11 in this area to remove the first metal layer 11 in this area. Then, the laser is continued to be used to irradiate the resin material in the through hole 210 in the dielectric layer 21 close to the circuit board body 001 to form a blind hole 30, and then a conductive layer is electroplated in the blind hole 30 to form a circuit board.

[0077] In an optional embodiment, Figure 8 A flow chart of a method for preparing a circuit board body provided by an embodiment of the present invention, Fig. 9 A schematic diagram of a process structure for preparing a circuit board body provided by an embodiment of the present invention is shown in FIG. Figure 8 As shown, the circuit board body is provided including:

[0078] S111. Provide at least two metal layers.

[0079] Specifically, refer to Figure 7 , the number of metal layers 10 is 3 layers. On the basis that the number of metal layers 10 provided is greater than 2 layers, the number of metal layers 10 can be set according to actual needs and is not specifically limited here.

[0080] S112. Provide at least one insulating layer.

[0081] Specifically, refer to Figure 7When the circuit board body 001 includes three metal layers 10, only two insulating layers 22 need to be provided. When the circuit board body 001 includes n metal layers 10, n-1 insulating layers 22 need to be provided. The insulating layer 22 includes insulating materials such as prepregs, and can be provided according to actual needs, and is not specifically limited here.

[0082] S113, alternately placing metal layers and insulating layers so that the insulating layer is located between two adjacent metal layers.

[0083] Specifically, the insulating layer 22 is placed between two adjacent metal layers 10 to bond the two metal layers 10 through the insulating layer 22 to improve the fit of the metal layers 10 and prevent short circuits of electrical signals between the metal layers 10 , thereby improving the working reliability of the metal layers 10 .

[0084] S114, pressing the metal layers and the insulating layers together to form a circuit board body.

[0085] Specifically, after the metal layer 10 and the insulating layer 22 are placed alternately, a pressing device can be used to provide pressure to press the alternately placed metal layer 10 and the insulating layer 22 together, thereby improving the bonding stability and reliability between the insulating layer 22 and the metal layer 10 and forming a firmly bonded circuit board body 001.

[0086] The technical solution provided by the embodiment of the present invention provides at least two metal layers and at least one insulating layer, alternately places the metal layers and the insulating layers, and then presses the metal layers and the insulating layers to form a circuit board body, so as to improve the bonding stability between the insulating layer and the metal layer.

[0087] Optional, Fig.10 Another schematic diagram of the process structure of preparing a circuit board body provided by an embodiment of the present invention is as follows: Fig.10 As shown, after laminating the metal layers 10 and the insulating layers 22, the laminating process also includes drilling holes in the metal layers 10 and the insulating layers 22 to form sub-through holes 230 that penetrate the metal layers 10 and the insulating layers 22; the sub-through holes 230 are electroplated, plugged, and polished in sequence to form the circuit board body 001.

[0088] The circuit board body 001 includes at least one sub-conducting hole 23. The sub-conducting hole 23 is used to conduct the metal layers 10 in the circuit board body 001. The setting position and setting number of the sub-conducting hole 23 in the circuit board body 001 can be set according to actual needs, and are not specifically limited here. For the convenience of description, only the circuit board body 001 including one sub-conducting hole 23 is used as an example for description.

[0089] Specifically, according to the design size of the sub-through hole 230, a drill bit of appropriate size can be selected to drill holes in the pressed metal layers 10 and the insulating layers 22 to drill out the sub-through hole 230; the sub-through hole 230 can be electroplated with copper by using electroplating equipment to form a conductive layer on the surface of the sub-through hole 230, so that electrical signals can be transmitted between the metal layers 10 in contact with the conductive layer on the surface of the sub-through hole 230. After the electroplating is completed, the original sub-through hole 230 becomes a sub-conducting hole 23 that can transmit electrical signals; in order to protect the conductive layer in the sub-conducting hole 23, the sub-conducting hole 23 after electroplating needs to be plugged, and the solder mask material for plugging includes ink or resin. After the plugging is completed, the excess resin on the surface of the circuit board body 001 can be removed by grinding equipment, and the resin in the sub-conducting hole 23 can be polished flat to improve the flatness of subsequent lamination. The conductive material plated on the through hole 230 includes copper or tin, etc., and the plugging process includes full-surface plugging or selective plugging, etc., which can be set according to actual needs.

[0090] The above description is about the case where the circuit board body includes a sub-conducting hole. When the circuit board body also includes a sub-conducting hole, the blind hole 30 in the circuit board may not overlap with the sub-conducting hole 23, or the blind hole 30 may overlap with the sub-conducting hole 23, which can be arranged according to actual needs. In an optional embodiment, Fig.11 A schematic diagram of the structure of another circuit board provided by an embodiment of the present invention, such as Fig.11 As shown, in the thickness direction Z of the circuit board, the blind via 30 at least partially overlaps with the sub-via 23 .

[0091] Specifically, the blind hole 30 is arranged to partially overlap the sub-via 23 so that the blind hole 30 is electrically connected to the sub-via 23, so that an electrical signal is transmitted to the sub-via 23 through the blind hole 30, or the electrical signal in the sub-via 23 is transmitted to the first metal layer 11 through the blind hole 30, so that the circuit board achieves certain electrical properties.

[0092] Optional, continue to refer to Fig.11 , the aperture of the blind hole 30 is a1, and the aperture of the sub-conducting hole 23 is A1; wherein, a1<A1.

[0093] Specifically, refer to Fig.11 By setting the aperture a1 of the blind hole 30 smaller than the aperture A1 of the sub-conducting hole 23, when the circuit board needs to set multiple blind holes 30 electrically connected to the sub-conducting holes 23, multiple blind holes 30 can be set in the dielectric layer 21 and the first metal layer 11 overlapping with the sub-conducting holes 23. While ensuring the conductive reliability of each blind hole 30, the circuit board can realize high-density blind hole setting, thereby improving the practicality of the circuit board.

[0094] Based on the same inventive concept, an embodiment of the present invention further provides a circuit board, which is manufactured using the circuit board manufacturing method provided by any embodiment of the present invention and has the same beneficial effects as the manufacturing method. The similarities can be referred to above and will not be repeated here.

[0095] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for preparing a circuit board, characterized in that: include: A dielectric layer, a first metal layer, and a circuit board body are provided; the dielectric layer comprises at least one through hole; the circuit board body comprises at least two metal layers and an insulating layer located between two adjacent metal layers; the dielectric layer comprises a prepreg; Laminating the circuit board body, the dielectric layer and the first metal layer in sequence; Performing laser drilling at the location of the through hole to form a blind hole penetrating the first metal layer and the dielectric layer; A conductive layer is electroplated in the blind hole to form the circuit board.

2. The preparation method according to claim 1, characterized in that: The aperture of the blind hole is a1, and the aperture of the through hole is a2; Among them, a2-a1≥4mil.

3. The preparation method according to claim 1, characterized in that: Before laser drilling is performed at the location of the through hole, the method further includes: The first metal layer away from the circuit board body is subjected to browning treatment.

4. The preparation method according to claim 1, characterized in that: Before sequentially laminating the circuit board body, the dielectric layer and the first metal layer, the method further includes: The through holes are plugged with resin.

5. The preparation method according to claim 1, characterized in that: The circuit board body is provided, comprising: providing at least two layers of said metal layer; Providing at least one insulating layer; Alternately placing the metal layers and the insulating layers so that the insulating layer is located between two adjacent metal layers; The metal layers and the insulating layers are laminated to form the circuit board body.

6. The preparation method according to claim 5, characterized in that: After laminating the metal layers and the insulating layers, the method further comprises: Drilling the pressed metal layers and the insulating layers to form sub-through holes penetrating the metal layers and the insulating layers; The sub-through hole is subjected to electroplating, plugging and polishing in sequence to form the circuit board body; the circuit board body includes at least one sub-through hole.

7. The preparation method according to claim 6, characterized in that: In the thickness direction of the circuit board, the blind via at least partially overlaps with the sub-via.

8. The preparation method according to claim 7, characterized in that: The aperture of the blind hole is a1, and the aperture of the sub-conducting hole is A1; Among them, a1<A1.

9. A circuit board, characterized in that: The circuit board is prepared by the method for preparing the circuit board according to any one of claims 1 to 8.

Images