Manufacturing method of multi-level blind hole interconnection structure and circuit board

Abstract

The present invention discloses a method for manufacturing a multi-level blind hole interconnection structure and a circuit board. The manufacturing method includes the following steps: prefabrication and lamination, prefabrication of a circuit board with multiple inner layer patterns, the circuit board including an inner base layer and an upper base layer, the inner base layer including a core board and a first copper layer disposed on the core board, at least two upper base layers stacked on the first copper layer, the upper base layer including a dielectric layer and a second copper layer disposed on the dielectric layer, the first copper layer and the second copper layer both being processed with inner layer patterns and hole pads; multi-level hole opening, starting from the outermost upper base layer and processing holes in the direction of the first copper layer, according to the needs of opening blind holes, opening copper holes at the hole pads of the second copper layer and dielectric holes in the dielectric layer by laser to form corresponding blind holes; electroplating and hole filling, filling the blind holes by electroplating and interconnecting multiple blind holes. The present invention is conducive to shortening the manufacturing cycle of the circuit board, and the resulting interconnection structure has good reliability and is convenient for production and application.

Description

Technical Field

[0001] The present invention relates to the technical field of printed circuit board manufacturing, and in particular to a manufacturing method of a multi-level blind hole interconnection structure and a circuit board. Background Art

[0002] For the processing of the multi-level blind hole interconnection structure of the existing circuit board, the current main solution is to use the method of layer-by-layer processing of laser blind holes and hole-filling electroplating to achieve multi-level blind hole interconnection by adding layers in sequence. Figure 1 and Figure 2 During production, the inner layer pattern and hole pads are first processed on the copper layer on the surface of the core board. A dielectric layer and copper layer are then laminated on top of it. The outer dielectric layer and copper layer are then laser-drilled to form blind holes. The blind holes are then electroplated and filled. After the inner layer pattern and hole pads are processed on the outer copper layer, the above operations of laminating the dielectric layer and copper layer, laser drilling, and electroplating are repeated as needed until the multi-level blind hole interconnect structure is completed. This method requires multiple laser and electroplating fillings, and the materials need to flow back and forth between different processing equipment. The processing and manufacturing cycle is long. In addition, such multi-level stacked holes have stress reliability issues, and the processing method needs to be improved. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for manufacturing a multi-level blind via interconnect structure. By first manufacturing a circuit board with a multi-layer inner layer pattern, without pre-drilling the via pads, the alignment of the multi-level blind vias is improved, and the exposure deviation and dimensional uniformity problems caused by pre-drilling the via pads of the multi-level blind vias are avoided. Subsequently, the via pads and dielectric layer are laser drilled, and finally the vias are uniformly filled by electroplating. This method is conducive to improving processing efficiency and shortening the manufacturing cycle. The resulting interconnect structure has good reliability and is convenient for production applications.

[0004] The present invention also provides a circuit board manufactured by adopting the manufacturing method of the multi-level blind hole interconnection structure.

[0005] The method for manufacturing a multi-level blind via interconnect structure according to the first embodiment of the present invention comprises the following steps:

[0006] Prefabricated lamination: a circuit board with multiple inner layer patterns is prefabricated. The circuit board includes an inner base layer and an upper base layer. The inner base layer includes a core board and a first copper layer provided on the core board. At least two upper base layers are stacked on the first copper layer. The upper base layer includes a dielectric layer and a second copper layer provided on the dielectric layer. The first copper layer and the second copper layer are both processed with inner layer patterns and hole pads.

[0007] Multi-stage hole drilling: starting from the outer upper base layer farthest from the inner base layer, hole processing is carried out in the direction of the first copper layer. Holes are processed on the upper base layer according to the need for opening blind holes. Copper holes are opened at the hole pads of the second copper layer and dielectric holes are opened in the dielectric layer by laser, so that the copper holes and dielectric holes form corresponding blind holes.

[0008] Electroplating filling: fill blind holes by electroplating and interconnect multiple blind holes.

[0009] The method for fabricating a multi-level blind via interconnect structure according to an embodiment of the present invention has at least the following beneficial effects: by first fabricating a circuit board having a multi-layer inner layer pattern, then laser drilling holes in the via pads and dielectric layers of each layer to produce a plurality of required blind vias, and then uniformly electroplating and filling the plurality of blind vias, this method improves processing efficiency, reduces the reciprocating flow of materials between different processing equipment, shortens the manufacturing cycle, and interconnects the blind vias of each level through simultaneous electroplating and filling, resulting in a highly reliable interconnect structure that is convenient for production applications.

[0010] According to some embodiments of the present invention, when performing the prefabrication lamination step, the inner layer graphics and hole pads are first processed on the first copper layer on the surface of the core board, and then the upper base layer is pressed layer by layer on the first copper layer. Each time a layer of the upper base layer is pressed, the inner layer graphics and hole pads are processed on the second copper layer of the upper base layer to obtain a circuit board with multiple layers of inner layer graphics.

[0011] According to some embodiments of the present invention, when performing the multi-stage drilling step, the via pads of the second copper layer and the dielectric layer are laser drilled layer by layer.

[0012] According to some embodiments of the present invention, when performing the multi-stage hole opening step, copper holes are opened at the hole pads of the second copper layer by ultraviolet laser lithography, and dielectric holes are opened in the dielectric layer by infrared laser lithography.

[0013] According to some embodiments of the present invention, when performing a multi-stage hole opening step, the wavelength range of the ultraviolet laser used to open copper holes at the hole pads of the second copper layer is 100-500nm, and the wavelength range of the infrared laser used to open dielectric holes in the dielectric layer is 500-1600nm.

[0014] According to some embodiments of the present invention, when performing a multi-stage drilling step, each time the via pads of the second copper layer and the dielectric layer are laser drilled, the same outer layer pattern target is used to align the circuit board.

[0015] According to some embodiments of the present invention, in the multi-stage hole-forming step, the diameter of the blind hole produced decreases gradually from the outermost second copper layer to the inner first copper layer.

[0016] According to some embodiments of the present invention, in the multi-stage hole opening step, the ratio of the depth dimension of the blind hole to the diameter dimension of the blind hole is in the range of 0.5-2.

[0017] According to some embodiments of the present invention, after the multi-step opening and before the electroplating filling step, the interior of the blind hole is cleaned by plasma processing, and then the inner wall of the blind hole is metallized by copper plating.

[0018] The circuit board according to the embodiment of the second aspect of the present invention is manufactured by using the method for manufacturing the multi-level blind hole interconnection structure according to the embodiment of the first aspect of the present invention.

[0019] The circuit board according to the embodiment of the present invention has at least the following beneficial effects: by adopting the above-mentioned method for manufacturing a multi-level blind hole interconnection structure, the manufacturing cycle of the circuit board can be shortened, and the blind holes of each level are simultaneously electroplated and filled to interconnect, so that the reliability of the manufactured interconnection structure is better and it is convenient for production and application.

[0020] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0022] Figure 1 This is a schematic diagram of a conventional processing solution for a multi-level blind via interconnect structure in the background art of the present invention;

[0023] Figure 2 This is a second schematic diagram of a processing solution for a conventional multi-level blind via interconnect structure in the background art of the present invention;

[0024] Figure 3 A schematic diagram of manufacturing a circuit board with multiple layers of inner layer patterns in a method for manufacturing a multi-level blind via interconnect structure according to an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of a method for manufacturing a multi-level blind via interconnect structure according to an embodiment of the present invention;

[0026] Figure 5 This is the second schematic diagram of the method for manufacturing a multi-level blind via interconnect structure according to an embodiment of the present invention.

[0027] Reference numerals:

[0028] First-order blind via 101 , second-order blind via 102 , third-order blind via 103 , core board 110 , via pad 111 , dielectric layer 120 , dielectric via 121 , second copper layer 130 , copper via 131 . DETAILED DESCRIPTION

[0029] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0030] In the description of the present invention, it should be understood that if orientation descriptions are involved, the orientations or positional relationships indicated, such as up, down, front, back, left, and right, are based on the orientations or positional relationships shown in the accompanying drawings. This is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0031] In the description of the present invention, if the words such as several, greater than, less than, exceed, above, below, within, etc. appear, among which, several means one or more, and more means more than two, greater than, less than, exceed, etc. are understood as not including the number itself, and above, below, within, etc. are understood as including the number itself.

[0032] If the first and second are described, they are only used to distinguish the technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0033] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0034] Reference Figure 1 and Figure 2Taking an eight-layer circuit board as an example, the processing scheme of the multi-level blind hole interconnection structure of the existing circuit board is explained: Step 1, first process the inner layer pattern and hole pad 111 on the copper layer on both sides of the core board 110; Step 2, respectively press the dielectric layer 120 and the copper layer on the copper layer on both sides of the core board 110; Step 3, according to the blind hole processing requirements, laser drill holes on the dielectric layer 120 and the copper layer on both sides to form the third-level blind hole 103; Step 4, electroplating the third-level blind hole 103 Filling the hole; Step 5, processing the inner layer pattern and the hole pad 111 on the outer copper layer; Step 6, respectively pressing the dielectric layer 120 and the copper layer on both sides; Step 7, according to the blind hole processing needs, laser drilling is performed on the dielectric layer 120 and the copper layer on both sides to form the second-order blind hole 102; Step 8, the second-order blind hole 102 is electroplated and filled; Step 9, processing the inner layer pattern and the hole pad 111 on the outer copper layer; Step 10, respectively pressing the dielectric layer 120 and the copper layer on both sides; Step 11 In the first step, according to the blind hole processing requirements, the dielectric layer 120 and the copper layer on the two outer sides are laser-drilled to form a first-order blind hole 101; In the next step, the first-order blind vias 101 are electroplated to complete the multi-level blind via interconnect structure of the eight-layer circuit board. This method requires multiple laser and electroplating fillings, and the material needs to flow back and forth between different processing equipment, resulting in a long processing cycle. In addition, this multi-level stacked via structure is delaminated, resulting in poor stress reliability.

[0035] Reference Figure 3 、 Figure 4 and Figure 5 The present invention proposes a method for manufacturing a multi-level blind hole interconnection structure, which comprises the following steps:

[0036] Prefabricated lamination: a circuit board with multiple inner layer patterns is prefabricated. The circuit board includes an inner base layer and an upper base layer. The inner base layer includes a core board 110 and a first copper layer provided on the core board 110. At least two upper base layers are stacked on the first copper layer. The upper base layer includes a dielectric layer 120 and a second copper layer 130 provided on the dielectric layer 120. The first copper layer and the second copper layer 130 are both processed with inner layer patterns and hole pads 111.

[0037] Multi-stage hole drilling: Starting from the outer upper base layer farthest from the inner base layer, hole processing is performed toward the first copper layer. Hole processing is performed on the upper base layer according to the need for opening blind holes. Copper holes 131 are opened at the hole pad 111 of the second copper layer 130 and dielectric holes 121 are opened in the dielectric layer 120 by laser, so that the copper holes 131 and the dielectric holes 121 form corresponding blind holes;

[0038] Electroplating filling: fill blind holes by electroplating and interconnect multiple blind holes.

[0039] The present invention first manufactures a circuit board with a multi-layer inner layer pattern, then laser-drills the hole pads 111 and the dielectric layer 120 of each layer to obtain a plurality of required blind holes, and then uniformly electroplates and fills the plurality of blind holes. This is beneficial to improving processing efficiency, reducing the reciprocating flow of materials in different processing equipment, shortening the manufacturing cycle, and interconnecting the blind holes of each stage through synchronous electroplating and filling, so that the obtained interconnection structure has better reliability and is convenient for production application.

[0040] In some embodiments, when performing the prefabrication lamination step, the inner layer pattern and the hole pad 111 are first processed on the first copper layer on the surface of the core board 110, and then the upper base layer is pressed layer by layer on the first copper layer. Each time a layer of the upper base layer is pressed, the inner layer pattern and the hole pad 111 are processed on the second copper layer 130 of the upper base layer to obtain a circuit board with multiple layers of inner layer patterns.

[0041] It is understandable that if Figure 3 As shown, taking the production of a circuit board with eight layers of inner layer patterns as an example, during the prefabrication stacking step, a first copper layer (not marked in the figure) is provided on both sides of the core board 110. The inner layer patterns and hole pads 111 are first processed on the first copper layers on both sides, and then an upper base layer is pressed on the first copper layers on both sides, with the second copper layer 130 located on the outside. Then, the inner layer patterns and hole pads 111 are processed on the second copper layers 130 on both sides, and then an upper base layer is pressed on the second copper layers 130 on both sides. After processing the inner layer patterns and hole pads 111 on the second copper layers 130 on both sides, an upper base layer is pressed on the second copper layers 130 on both sides, and the inner layer patterns and hole pads 111 are processed on the second copper layers 130 on both sides, thereby obtaining a circuit board with eight layers of inner layer patterns. By laminating the base layer layer by layer and processing the inner layer graphics and the hole pad 111, it is beneficial to the subsequent continuous hole opening operation, and the hole pad 111 is not opened in advance, which is beneficial to improving the alignment of the multi-level blind holes and avoiding the exposure deviation and size uniformity problems caused by the pre-opening of the multi-level blind hole pad 111.

[0042] In some embodiments, during the multi-stage hole drilling step, laser drilling is performed on the hole pads 111 of the second copper layer 130 and the dielectric layer 120 in a layer-by-layer drilling manner. It is understandable that during the manufacturing process, laser drilling is first performed on the hole pads 111 of the outermost second copper layer 130, and then the dielectric layer 120 of the next layer is drilled, and then the hole pads 111 of the next layer are drilled again, and so on. The holes are drilled layer by layer, and multiple laser drillings are performed, which is beneficial to improving the hole shape of the blind hole and increasing the processing layer capacity of the multi-stage blind hole.

[0043] In some embodiments, when performing the multi-stage hole opening step, the copper hole 131 is opened at the hole pad 111 of the second copper layer 130 by ultraviolet laser lithography, and the dielectric hole 121 is opened in the dielectric layer 120 by infrared laser lithography.

[0044] It is understandable that since the absorption rate of metallic copper increases with decreasing wavelength, copper has a good absorption rate for ultraviolet lasers, and ultraviolet lasers have a short wavelength and a small processing heat-affected zone, using ultraviolet laser copper breaking is conducive to forming copper holes 131 of the required diameter at the hole pad 111 of the second copper layer 130, facilitating the subsequent opening of the dielectric layer 120; since the material of the dielectric layer 120 has a good absorption rate for infrared lasers, using infrared laser to open the dielectric layer 120 is conducive to forming dielectric holes 121 of the required diameter and depth, facilitating processing to the surface of the hole pad 111 of the next layer, and helping to avoid damage to the hole pad 111 of the next layer. The scheme of alternating multiple ultraviolet laser copper breaking and infrared laser opening of the dielectric layer 120 can further improve the processing layer capacity of multi-level blind holes and improve the hole shape of the blind holes.

[0045] In some embodiments, when performing the multi-stage hole-drilling step, the wavelength range of the ultraviolet laser used to drill the copper hole 131 at the hole pad 111 of the second copper layer 130 is 100-500 nm, and the wavelength range of the infrared laser used to drill the dielectric hole 121 in the dielectric layer 120 is 500-1600 nm. By using ultraviolet laser and infrared laser in the above wavelength ranges, it can be well suited for drilling the hole pad 111 and the dielectric layer 120, and is convenient to use.

[0046] When drilling the hole pad 111, the energy, pulse frequency and pulse width of the ultraviolet laser are adjusted according to the thickness of the copper layer of the hole pad 111, thereby controlling the diameter of the copper hole 131. The thickness range of the ultraviolet laser copper breaking is 1 to 35 μm, and the diameter is 15 to 500 μm. When drilling the dielectric layer 120, the energy, pulse frequency and pulse width of the infrared laser are adjusted according to the thickness of the dielectric layer 120, thereby controlling the thickness and diameter of the hole in the dielectric layer 120.

[0047] In some embodiments, during the multi-stage hole drilling process, each laser drilling of the via pad 111 of the second copper layer 130 and the dielectric layer 120 is performed using the same outer pattern target to align the circuit board. It is understood that using the same outer pattern target to align the circuit board helps ensure the alignment of the multi-stage blind hole processing, avoids blind hole deviation, and facilitates use.

[0048] In some embodiments, in the multi-stage hole opening step, the diameter of the blind hole produced decreases from the outermost second copper layer 130 to the inner first copper layer. Figure 5 As shown, the diameter of the blind hole decreases from the outermost second copper layer 130 to the inner first copper layer, so that the hole wall of the blind hole has a certain taper change, and the hole diameter decreases as the depth of the hole increases, which is beneficial to the subsequent electroplating filling and is easy to use.

[0049] In some embodiments, in the multi-stage hole opening step, the ratio of the blind hole depth dimension / the blind hole diameter dimension produced is in the range of 0.5 to 2. By controlling the ratio of the blind hole depth dimension / the blind hole diameter dimension in the range of 0.5 to 2, subsequent electroplating hole filling is facilitated.

[0050] In some embodiments, after the multi-step opening is performed and before the electroplating filling step is performed, the interior of the blind hole is cleaned by plasma processing, and then the inner wall of the blind hole is metallized by copper plating.

[0051] It is understandable that before the electroplating hole filling step, the interior of the blind hole is cleaned by plasma processing to remove residual glue residue in the hole, and then copper is processed to metalize the inner wall of the blind hole to facilitate subsequent electroplating hole filling.

[0052] Reference Figure 4 and Figure 5 Taking the interconnection of the first-order blind via 101, the second-order blind via 102 and the third-order blind via 103 in an eight-layer circuit board as an example, the method for manufacturing the multi-order blind via interconnection structure of the present invention is specifically described:

[0053] A circuit board with eight inner layer patterns is produced, with upper, middle and lower layers of the inner base layer provided on both sides, and multi-step blind via pads 111 pre-made on the first and second copper layers 130;

[0054] Using the outer pattern target alignment, a 354nm wavelength ultraviolet laser is used to laser-break the hole pad 111 of the upper second copper layer 130 at a preset position. The copper breaking thickness is 18um, forming a copper hole 131 with an opening diameter of 120um.

[0055] Using the same outer layer pattern target for alignment, a carbon dioxide infrared laser with a wavelength of 1064nm is used to laser-cut a dielectric hole 121 in the dielectric layer 120 at the location of the upper copper hole 131. The upper copper hole 131 and the dielectric hole 121 form a first-order blind hole 101 with a depth of 50μm, an upper aperture of 120μm, and a lower aperture of 100μm.

[0056] Using the same outer layer pattern target alignment, a 354nm wavelength ultraviolet laser is used to perform laser copper breaking on the hole pad 111 of the second copper layer 130 of the middle layer at a preset position. The copper breaking thickness is 18um, forming a copper hole 131 with an opening diameter of 100um.

[0057] Using the same outer layer pattern target for alignment, a carbon dioxide infrared laser with a wavelength of 1064nm is used to laser-cut a dielectric hole 121 in the dielectric layer 120 at the location of the middle layer copper hole 131. The middle layer copper hole 131 and the dielectric hole 121 form a second-order blind hole 102 with a depth of 50μm, an upper aperture of 100μm, and a lower aperture of 80μm.

[0058] Using the same outer layer pattern target for alignment, a 354nm wavelength ultraviolet laser is used to laser-break the hole pad 111 of the lower second copper layer 130 at a preset position. The copper breaking thickness is 18um, forming a copper hole 131 with an opening diameter of 80um.

[0059] Using the same outer layer pattern target for alignment, a carbon dioxide infrared laser with a wavelength of 1064nm is used to laser-cut a dielectric hole 121 in the dielectric layer 120 at the location of the lower copper hole 131. The lower copper hole 131 and the dielectric hole 121 form a third-order blind hole 103 with a depth of 50μm, an upper aperture of 80μm, and a lower aperture of 60μm.

[0060] The inside of each level of blind holes is cleaned by plasma processing to remove residual glue residue in the hole, and then copper is processed to metallize the hole wall. Finally, the blind holes of each level are filled and interconnected by electroplating.

[0061] The present invention does not pre-process the hole pad 111 of the second copper layer 130. After the circuit board with the multi-layer inner layer pattern is completed, the processing scheme of multiple ultraviolet laser hole pad 111 openings + infrared laser medium layer 120 openings is adopted. This can further improve the processing layer number capability of the multi-level blind hole, which is beneficial to improving the hole shape and alignment of the multi-level blind hole, and avoids the exposure deviation and size uniformity problems caused by pre-etching the copper holes 131 of the multi-level blind hole. After the multiple required blind holes are produced, the multiple blind holes are uniformly electroplated and filled, which is beneficial to improving the processing efficiency, reducing the reciprocating flow of materials in different processing equipment, shortening the manufacturing cycle, and the simultaneous electroplating and filling of the blind holes of each level is interconnected, so that the reliability of the obtained interconnection structure is better and it is convenient for production application.

[0062] In actual application, the inner base layer can also be provided with an upper base layer on one side, and the number of upper base layers on one side can also be two layers, four layers or more. The thickness of each second copper layer 130, the thickness of the dielectric layer 120, the laser wavelength used for laser opening, etc. can all be set accordingly according to actual use needs.

[0063] The circuit board according to the second embodiment of the present invention is manufactured by using the method for manufacturing the multi-level blind hole interconnection structure according to the first embodiment of the present invention.

[0064] According to the circuit board of the embodiment of the present invention, by adopting the above-mentioned method for manufacturing the multi-level blind hole interconnection structure, the manufacturing cycle of the circuit board can be shortened, and the blind holes of each level are simultaneously electroplated and filled to interconnect, so that the reliability of the manufactured interconnection structure is better and it is convenient for production and application.

[0065] Since other components of the circuit board according to the embodiment of the present invention are well known to those skilled in the art, they will not be described in detail here.

[0066] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the scope of the present invention.

Claims

1. A method for manufacturing a multi-level blind hole interconnection structure, characterized in that: The following steps are involved: Prefabricated lamination: a circuit board with multiple inner layer patterns is prefabricated. The circuit board includes an inner base layer and an upper base layer. The inner base layer includes a core board and a first copper layer provided on the core board. At least two upper base layers are stacked on the first copper layer. The upper base layer includes a dielectric layer and a second copper layer provided on the dielectric layer. The first copper layer and the second copper layer are both processed with inner layer patterns and hole pads. Multi-stage hole drilling: starting from the outer upper base layer farthest from the inner base layer, hole processing is carried out in the direction of the first copper layer. Holes are processed on the upper base layer according to the need for opening blind holes. Copper holes are opened at the hole pads of the second copper layer and dielectric holes are opened in the dielectric layer by laser, so that the copper holes and dielectric holes form corresponding blind holes. Electroplating filling: filling blind holes by electroplating and interconnecting multiple blind holes; When performing the multi-stage hole opening step, the hole pad of the second copper layer and the dielectric layer are laser opened layer by layer, copper holes are opened at the hole pad of the second copper layer by ultraviolet laser, and dielectric holes are opened in the dielectric layer by infrared laser.

2. The method for manufacturing a multi-level blind via interconnect structure according to claim 1, wherein: During the prefabrication lamination step, the inner layer pattern and hole pad are first processed on the first copper layer on the surface of the core board, and then the upper base layer is pressed layer by layer on the first copper layer. Each time a layer of the upper base layer is pressed, the inner layer pattern and hole pad are processed on the second copper layer of the upper base layer to produce a circuit board with multiple layers of inner layer patterns.

3. The method for manufacturing a multi-level blind via interconnect structure according to claim 1, wherein: During the multi-stage hole opening step, the wavelength range of the ultraviolet laser used to open the copper hole at the hole pad of the second copper layer is 100-500nm, and the wavelength range of the infrared laser used to open the dielectric hole in the dielectric layer is 500-1600nm.

4. The method for manufacturing a multi-level blind via interconnect structure according to claim 1, wherein: When performing the multi-stage hole opening step, each time the hole pad of the second copper layer and the dielectric layer are laser opened, the same outer layer pattern target is used to align the circuit board.

5. The method for manufacturing a multi-level blind via interconnect structure according to claim 1, wherein: In the multi-stage hole opening step, the diameter of the blind hole produced decreases gradually from the outermost second copper layer to the inner first copper layer.

6. The method for manufacturing a multi-level blind via interconnect structure according to claim 5, wherein: In the multi-stage hole opening step, the ratio of the depth dimension of the blind hole to the diameter dimension of the blind hole is in the range of 0.5 to 2.

7. The method for manufacturing a multi-level blind via interconnect structure according to claim 1, wherein: After the multi-step opening is performed and before the electroplating filling step is performed, the interior of the blind hole is cleaned by plasma processing, and then the inner wall of the blind hole is metallized by copper treatment.

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