HDI circuit board and method for detecting offset of blind holes in HDI circuit board

Abstract

The present invention discloses an HDI circuit board and a method for detecting the offset of a blind hole of the HDI circuit board. The HDI circuit board includes a substrate and a test module. The substrate is provided with a through hole and a blind hole. The test module includes a first copper ring group and a second copper ring group. The first copper ring group is provided at the periphery of the through hole, and the second copper ring group is provided at the periphery of the blind hole. The first copper ring group includes a conductive layer and a plurality of first copper rings. The conductive layer is provided on the sidewall of the through hole. The plurality of first copper rings are electrically connected through the conductive layer. The second copper ring group includes a conductive rod and a plurality of second copper rings. The inner diameter of the second copper ring located at the bottom is larger than the inner diameter of the copper ring located at the top. The second copper ring located at the bottom is electrically connected to the corresponding first copper ring. The conductive rod is inserted into the blind hole. An isolation ring is formed between the outer peripheral side of the conductive rod at one end close to the blind hole and the inner side of the second copper ring located at the bottom. If the first copper ring located at the top and the second copper ring located at the top are conductive, the HDI circuit board can be judged as unqualified.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit boards, and in particular to an HDI circuit board and a method for detecting the offset of a blind hole of the HDI circuit board. Background Art

[0002] HDI is a technology for producing printed circuit boards. HDI circuit boards are circuit boards with relatively high circuit distribution density using micro blind buried via technology.

[0003] During the production of HDI circuit boards, blind vias are made by laser drilling. Laser offset may cause the inner layers of the HDI circuit boards to shift. During the production process, the inner layer offset cannot be confirmed in time and can only be discovered after electrical testing is completed, resulting in wasted production costs. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides an HDI circuit board that can promptly confirm whether the blind hole processing is qualified.

[0005] The present invention also provides a method for detecting the offset of blind vias in an HDI circuit board.

[0006] An HDI circuit board according to an embodiment of a first aspect of the present invention includes a substrate and a test module, wherein the substrate is provided with a through hole and a blind hole, both of which are arranged along the thickness direction of the substrate. The test module is arranged on the substrate and includes a first copper ring group and a second copper ring group, wherein the first copper ring group is arranged around the periphery of the through hole, and the second copper ring group is arranged around the periphery of the blind hole. The first copper ring group includes a conductive layer and a plurality of first copper rings spaced apart along the thickness direction of the substrate, the conductive layer is arranged on the sidewall of the through hole, and the plurality of first copper rings are electrically connected through the conductive layer; the second copper ring group includes a conductive rod and a plurality of second copper rings spaced apart along the thickness direction of the substrate, the inner diameter of the second copper ring located at the bottom is larger than the inner diameter of the second copper ring located at the top, and the second copper ring located at the bottom is electrically connected to the corresponding first copper ring. The conductive rod is inserted into the blind hole, and an isolation ring is formed between the outer periphery of the conductive rod at one end near the blind hole and the inner side of the second copper ring located at the bottom.

[0007] The HDI circuit board according to the first embodiment of the present invention has at least the following beneficial effects:

[0008] During laser drilling, the operator can design the diameter of the blind hole according to the process requirements of the blind hole and the inner diameter of the second copper ring at the bottom, so that the width of the isolation ring is the offset threshold of the blind hole. If the first copper ring at the top and the second copper ring at the top are conductive, it can be determined that the conductive rod partially overlaps with the second copper ring at the bottom, and the offset of the conductive rod is greater than the width of the isolation ring. The offset of the blind hole is too large and the HDI circuit board is unqualified. If the first copper ring at the top and the second copper ring at the top are not conductive, it can be determined that the conductive rod does not overlap with the second copper ring at the bottom, and the offset of the conductive rod is less than the width of the isolation ring. It can be timely determined whether the offset of the blind hole is within the process requirements to determine whether the HDI circuit board is qualified.

[0009] According to some embodiments of the present invention, there are multiple test modules, and the multiple test modules are arranged at intervals along the length direction of the substrate. Along the length direction of the substrate, the widths of the multiple isolation rings gradually increase or decrease.

[0010] According to some embodiments of the present invention, along the length direction of the substrate, the widths of the plurality of isolation rings form an arithmetic progression.

[0011] According to some embodiments of the present invention, along the length direction of the substrate, the widths of the plurality of isolation rings increase sequentially by 0.5 mi.

[0012] According to some embodiments of the present invention, a plurality of first test PADs and second test PADs are further included, wherein the first test PADs and the second test PADs are both arranged on the surface of the substrate, the first test PADs are electrically connected to the conductive layer, and the second test PADs are electrically connected to the conductive rods.

[0013] According to some embodiments of the present invention, the first copper ring group and the second copper ring group are arranged along the width direction of the substrate, the first test PAD is arranged on a side of the first copper ring group away from the second copper ring group, and the second test PAD is arranged on a side of the second copper ring group away from the first copper ring group.

[0014] According to some embodiments of the present invention, a diameter of the first test PAD or the second test PAD is 0.5 mm to 1.5 mm.

[0015] According to some embodiments of the present invention, the diameter of the blind hole is 2mil to 6mil.

[0016] According to a second aspect of the present invention, a method for detecting an offset of a blind via in an HDI circuit board includes the following steps:

[0017] S1: Obtain a substrate, and make a plurality of test modules on the substrate, wherein the test modules include a first copper ring group and a second copper ring group, wherein the first copper ring group includes a plurality of first copper rings spaced apart along the thickness direction of the substrate, and the second copper ring group includes a plurality of second copper rings spaced apart along the thickness direction of the substrate, wherein the inner diameter of the second copper ring at the bottom is greater than the inner diameter of the second copper ring at the top, and the inner diameters of the second copper rings at the bottom of different second copper ring groups are inconsistent; S2: Process a through hole in the first copper ring group, and copper-plate the inner wall of the through hole, so that the first copper ring group and the corresponding second copper ring group at the bottom are spaced apart. Electrical connection; S3: Laser drilling the blind holes in the second copper ring group, with the diameter of the blind holes on each second copper ring group being the same; S4: Filling the blind holes with copper to form conductive rods, forming an isolation ring between the outer peripheral side of one end of the conductive rod close to the bottom wall of the blind hole and the inner side of the second copper ring at the bottom, with the width of the isolation ring being the distance between the outer side of the conductive rod and the second copper ring at the bottom; S5: Obtain a multimeter, electrically connect the red and black test leads of the multimeter to the first and second copper ring groups on the same test module, respectively, and test multiple test modules one by one. The test results are analyzed as follows:

[0018] S5.1: If multiple test modules show short circuits, the offset of the blind hole is greater than the minimum value of the widths of the different isolation rings; S5.2: If multiple test modules show open circuits, the offset of the blind hole is less than the maximum value of the widths of the different isolation rings; S5.3: If some test modules show short circuits and some test modules show open circuits, the offset of the blind hole is less than the minimum value of the width of the isolation ring in the test module showing open circuits, and greater than the maximum value of the width of the isolation ring in the test module showing short circuits.

[0019] The method for detecting the offset of blind vias in an HDI circuit board according to the second aspect of the present invention has at least the following beneficial effects:

[0020] When multiple test modules all show short circuits, it is determined that the offset of the blind hole is greater than the minimum value of the widths of different isolation rings; when multiple test modules all show open circuits, it is determined that the offset of the blind hole is less than the maximum value of the widths of different isolation rings; when some test modules show short circuits and some test modules show open circuits, it is determined that the offset of the blind hole is less than the minimum value of the width of the isolation ring in the test module showing the open circuit and greater than the maximum value of the width of the isolation ring in the test module showing the short circuit. In this way, the offset of the blind hole can be accurately determined to facilitate monitoring of the drilling quality of the blind hole.

[0021] 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

[0022] 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:

[0023] Figure 1 1 is a top view of an HD I circuit board according to an embodiment of the present invention;

[0024] Figure 2 for Figure 1 Sectional view along line AA.

[0025] Reference numerals:

[0026] Substrate 100 , through hole 110 , blind via 120 , first copper ring group 210 , conductive layer 211 , first copper ring 212 , second copper ring group 220 , conductive rod 221 , second copper ring 222 , first test PAD 310 , second test PAD 320 . DETAILED DESCRIPTION

[0027] 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.

[0028] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do 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, they cannot be understood as limitations on the present invention.

[0029] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0030] 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.

[0031] Reference Figure 1 、 Figure 2 According to the first embodiment of the present invention, the HD I circuit board includes a substrate 100 and a test module. The substrate 100 is provided with a through hole 110 and a blind hole 120. The through hole 110 and the blind hole 120 are both arranged along the thickness direction of the substrate 100. The test module is arranged on the substrate 100. The test module includes a first copper ring group 210 and a second copper ring group 220. The first copper ring group 210 is arranged around the through hole 110, and the second copper ring group 220 is arranged around the blind hole 120. The first copper ring group 210 includes a conductive layer 211 and a plurality of first copper rings 212 arranged at intervals along the thickness direction of the substrate 100. The conductive layer 211 is arranged on the side wall of the through hole 110. The plurality of first copper rings 212 are electrically connected through the conductive layer 211. The second copper ring group 220 includes a conductive rod 221 and Multiple second copper rings 222 are spaced apart along the thickness direction of the substrate 100. The inner diameter of the second copper ring 222 at the bottom is larger than the inner diameter of the second copper ring 222 at the top. The second copper ring 222 at the bottom is electrically connected to the corresponding first copper ring 212. A conductive rod 221 is inserted into the blind hole 120. An isolation ring is formed between the outer periphery of the conductive rod 221 at one end near the blind hole 120 and the inner side of the second copper ring 222 at the bottom. If the first copper ring 212 at the top and the second copper ring 222 at the top are electrically connected, it can be determined that the conductive rod 221 partially overlaps with the second copper ring 222 at the bottom, and the offset of the conductive rod 221 is greater than the width of the isolation ring. This indicates that the offset of the blind hole 120 is too large, and the HDI circuit board is unqualified. If the first copper ring 212 at the top and the second copper ring 222 at the top are not electrically connected, it can be determined that the conductive rod 221 does not overlap with the second copper ring 222 at the bottom, and the offset of the conductive rod 221 is less than the width of the isolation ring, and the HDI circuit board is qualified.

[0032] Specifically, during laser drilling, the operator can design the diameter of the blind hole 120 based on the process requirements of the blind hole 120 and the inner diameter of the second copper ring 222 at the bottom, so that the width of the isolation ring is the offset threshold of the blind hole 120. If the first copper ring 212 at the top and the second copper ring 222 at the top are conductive, it can be determined that the conductive rod 221 and the second copper ring 222 at the bottom partially overlap, and the offset of the conductive rod 221 is greater than the width of the isolation ring. In this way, the offset of the blind hole 120 is too large, and the HDI circuit board is unqualified. If the first copper ring 212 at the top and the second copper ring 222 at the top are not conductive, it can be determined that the conductive rod 221 and the second copper ring 222 at the bottom do not overlap, and the offset of the conductive rod 221 is less than the width of the isolation ring. This allows timely determination of whether the offset of the blind hole 120 is within the process requirements, thereby ensuring that the HDI circuit board is qualified.

[0033] In some embodiments of the present invention, there are five test modules, which are arranged at intervals along the length direction of the substrate 100. Along the length direction of the substrate 100, the widths of the multiple isolation rings gradually increase, which can detect the range of the offset of the blind hole 120 to effectively monitor the drilling quality of the blind hole 120.

[0034] Specifically, the second copper rings 222 at the bottom are arranged in an orderly interval along the length direction of the substrate 100, which can facilitate the inspection personnel to orderly inspect whether the first copper ring group 210 and the second copper ring group 220 are conductive, so as to determine whether the offset of the blind hole 120 is qualified.

[0035] It is understandable that the widths of the plurality of isolation rings may be gradually reduced along the length direction of the substrate 100 , which is not limited here.

[0036] It should be noted that the number of test modules may be two or three, etc., which is not limited here.

[0037] In some embodiments of the present invention, along the length direction of the substrate 100, the widths of the five isolation rings form an arithmetic progression, which can facilitate inspection personnel to orderly detect whether the first copper ring group 210 and the second copper ring group 220 are conductive, so as to determine whether the offset of the blind hole 120 is qualified.

[0038] In some embodiments of the present invention, the widths of the five isolation rings increase by 0.5 mi l along the length direction of the substrate 100, which can facilitate the inspection personnel to orderly detect whether the first copper ring group 210 and the second copper ring group 220 are conductive, so as to determine whether the offset of the blind hole 120 is qualified.

[0039] It should be noted that 1mil is equal to 0.0254mm, which is not limited here.

[0040] In some embodiments of the present invention, multiple first test PADs 310 and second test PADs 320 are further included. The first test PADs 310 and second test PADs 320 are both arranged on the surface of the substrate 100. The first test PADs 310 are electrically connected to the conductive layer 211, and the second test PADs 320 are electrically connected to the conductive rods 221. In this way, by providing the first test PADs 310 and the second test PADs 320, it is convenient for the inspector to use the red and black test leads of a multimeter to contact the first test PADs 310 and the second test PADs 320 respectively to test whether the first copper ring group 210 and the second copper ring group 220 are connected.

[0041] Specifically, by setting the first test PAD310 and the second test PAD320, the test area of ​​the first copper ring group 210 and the test area of ​​the second copper ring group 220 can be increased to reduce the detection difficulty of the detection personnel, thereby making it easier for the detection personnel to test whether the first copper ring group 210 and the second copper ring group 220 are connected.

[0042] It should be noted that the first test PAD 310 and the second test PAD 320 are both copper layers disposed on the surface of the substrate 100 , which will not be described in detail herein.

[0043] In some embodiments of the present invention, the first copper ring group 210 and the second copper ring group 220 are arranged along the width direction of the substrate 100, the first test PAD 310 is arranged on the side of the first copper ring group 210 away from the second copper ring group 220, and the second test PAD 320 is arranged on the side of the second copper ring group 220 away from the first copper ring group 210. This can reduce the occurrence of misdetection of the first copper ring group 210 and the second copper ring group 220 between different test modules by the inspectors, thereby improving the detection reliability of the inspectors.

[0044] In some embodiments of the present invention, the diameter of the first test PAD310 or the second test PAD320 is 0.5 mm to 1.5 mm. When the diameter of the first test PAD310 or the second test PAD320 is less than 0.5 mm, the size of the first test PAD310 or the second test PAD320 is too small to facilitate detection by the inspector. When the diameter of the first test PAD310 or the second test PAD320 is greater than 1.5 mm, the size of the first test PAD310 or the second test PAD320 is too large, and the space occupied by the substrate 100 increases, resulting in a decrease in the wiring density of the substrate 100. By setting the diameter of the first test PAD310 or the second test PAD320 to 0.5 mm to 1.5 mm, it is not only convenient for the inspector to detect, but also the wiring density of the substrate 100 can be guaranteed.

[0045] Specifically, the diameter of the first test PAD 310 or the second test PAD 320 is 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, or 1.5 mm, which is not limited here.

[0046] In some embodiments of the present invention, the diameter of the blind hole 120 is 2 mil to 6 mil. When the diameter of the blind hole 120 is less than 2 mil, the diameter of the blind hole 120 is too small, resulting in increased difficulty in processing the blind hole 120. When the diameter of the blind hole 120 is greater than 6 mil, the diameter of the blind hole 120 is too large, resulting in a decrease in the wiring density of the substrate 100. By setting the diameter of the blind hole 120 to 2 mil to 6 mil, not only can the processing difficulty of the blind hole 120 be reduced, but also the wiring density of the substrate 100 can be guaranteed.

[0047] Specifically, the diameter of the blind hole 120 can be 2mil, 3mil, 4mil, 5mil, or 6mil, which is not limited here.

[0048] Reference Figure 1 、 Figure 2 According to the second embodiment of the present invention, the method for detecting the offset of the blind hole 120 of the HD I circuit board includes the following steps: S1: obtaining a substrate 100, and making multiple test modules on the substrate 100, the test modules including a first copper ring group 210 and a second copper ring group 220, the first copper ring group 210 including a plurality of first copper rings 212 spaced apart along the thickness direction of the substrate 100, the second copper ring group 220 including a plurality of second copper rings 222 spaced apart along the thickness direction of the substrate 100, the inner diameter of the second copper ring 222 located at the bottom is larger than the inner diameter of the second copper ring 222 located at the top, and the inner diameters of the second copper rings 222 located at the bottom of different second copper ring groups 220 are inconsistent; S2: processing a through hole 110 in the first copper ring group 210, and copper plating the inner wall of the through hole 110 so that the first copper ring group 210 is aligned with the inner wall of the through hole 110. The corresponding second copper ring 222 at the bottom of the second copper ring group 220 is electrically connected; S3: blind holes 120 are processed in the second copper ring group 220 by laser drilling, and the diameter of the blind holes 120 on each second copper ring group 220 is consistent; S4: copper is filled in the blind hole 120 to form a conductive rod 221, and an isolation ring is formed between the outer peripheral side of one end of the conductive rod 221 close to the bottom wall of the blind hole 120 and the inner side of the second copper ring 222 at the bottom. The width of the isolation ring is the distance between the outer side of the conductive rod 221 and the second copper ring 222 at the bottom; S5; obtain a multimeter, electrically connect the red and black test leads of the multimeter to the first copper ring group 210 and the second copper ring group 220 on the same test module respectively, and test multiple test modules one by one;

[0049] The test results are analyzed as follows: S5.1: If multiple test modules show a short circuit, the offset of the blind hole 120 is greater than the minimum value of the width of different isolation rings; S5.2: If multiple test modules show an open circuit, the offset of the blind hole 120 is less than the maximum value of the width of different isolation rings; S5.3: If some test modules show a short circuit and some test modules show an open circuit, the offset of the blind hole 120 is less than the minimum value of the width of the isolation ring in the test module showing the open circuit and greater than the maximum value of the width of the isolation ring in the test module showing the short circuit. The range of the offset of the blind hole 120 can be detected to determine whether the offset of the blind hole 120 is qualified.

[0050] Specifically, when multiple test modules all show a short circuit, it is determined that the offset of the blind hole 120 is greater than the minimum value of the width of different isolation rings; when multiple test modules all show an open circuit, it is determined that the offset of the blind hole 120 is less than the maximum value of the width of different isolation rings; when some test modules show a short circuit and some test modules show an open circuit, it is determined that the offset of the blind hole 120 is less than the minimum value of the width of the isolation ring in the test module showing the open circuit and greater than the maximum value of the width of the isolation ring in the test module showing the short circuit. In this way, the offset of the blind hole 120 can be accurately determined to facilitate monitoring of the drilling quality of the blind hole 120.

[0051] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] The embodiment is described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiment. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the present invention.

Claims

1. A method for detecting the offset of a blind hole in an HDI circuit board, characterized in that: The following steps are involved: S1: obtaining a substrate (100), and manufacturing a plurality of test modules on the substrate (100), wherein the test modules include a first copper ring group (210) and a second copper ring group (220), wherein the first copper ring group (210) includes a plurality of first copper rings (212) spaced apart along a thickness direction of the substrate (100), and the second copper ring group (220) includes a plurality of second copper rings (222) spaced apart along a thickness direction of the substrate (100), wherein the inner diameter of the second copper ring (222) at the bottom is larger than the inner diameter of the second copper ring (222) at the top, and the inner diameters of the second copper rings (222) at the bottom of different second copper ring groups (220) are different; S2: machining a through hole (110) in the first copper ring group (210), and copper plating the inner wall of the through hole (110) to electrically connect the first copper ring group (210) to the corresponding second copper ring (222) located at the bottom of the second copper ring group (220); S3: processing the blind holes (120) in the second copper ring group (220) by laser drilling, wherein the diameters of the blind holes (120) on each second copper ring group (220) are the same; S4: Copper is filled in the blind hole (120) to form a conductive rod (221), an isolation ring is formed between the outer peripheral side of one end of the conductive rod (221) close to the bottom wall of the blind hole (120) and the inner side of the second copper ring (222) located at the bottom, and the width of the isolation ring is the distance between the outer side of the conductive rod (221) and the second copper ring (222) located at the bottom; S5: Obtain a multimeter, electrically connect the red test lead and the black test lead of the multimeter to the first copper ring group (210) and the second copper ring group (220) on the same test module, and test multiple test modules one by one. The test results are analyzed as follows: S5.1: If the plurality of test modules all show a short circuit, the offset of the blind hole (120) is greater than the minimum value of the width of the different isolation rings; S5.2: If the plurality of test modules all show a short circuit, the offset of the blind hole (120) is smaller than the maximum value of the widths of the different isolation rings; S5.3: If some of the test modules show a short circuit and some of the test modules show an open circuit, the offset of the blind hole (120) is smaller than the minimum width of the isolation ring in the test module showing an open circuit and larger than the maximum width of the isolation ring in the test module showing a short circuit.

2. An HDI circuit board, characterized in that: The method for detecting the offset of a blind hole of an HDI circuit board according to claim 1 is obtained, wherein the HDI circuit board comprises: A substrate (100) is provided with a through hole (110) and a blind hole (120), wherein the through hole (110) and the blind hole (120) are both arranged along the thickness direction of the substrate (100); A test module is provided on the substrate (100), the test module comprising a first copper ring group (210) and a second copper ring group (220), the first copper ring group (210) being provided on the periphery of the through hole (110), and the second copper ring group (220) being provided on the periphery of the blind hole (120); The first copper ring group (210) comprises a conductive layer (211) and a plurality of first copper rings (212) spaced apart along the thickness direction of the substrate (100); the conductive layer (211) is provided on the side wall of the through hole (110); and the plurality of first copper rings (212) are electrically connected via the conductive layer (211); The second copper ring group (220) comprises a conductive rod (221) and a plurality of second copper rings (222) spaced apart along the thickness direction of the substrate (100); the inner diameter of the second copper ring (222) located at the bottom is larger than the inner diameter of the second copper ring (222) located at the top; the second copper ring (222) located at the bottom is electrically connected to the corresponding first copper ring (212); the conductive rod (221) is inserted into the blind hole (120); an isolation ring is formed between the outer peripheral side of one end of the conductive rod (221) close to the blind hole (120) and the inner side of the second copper ring (222) located at the bottom.

3. The HDI circuit board according to claim 2, characterized in that: The test modules are arranged in plurality, and the plurality of test modules are arranged at intervals along the length direction of the substrate (100). Along the length direction of the substrate (100), the widths of the plurality of isolation rings gradually increase or decrease.

4. The HDI circuit board according to claim 3, characterized in that: Along the length direction of the substrate (100), the widths of the plurality of isolation rings form an arithmetic progression.

5. The HDI circuit board according to claim 4, characterized in that: Along the length direction of the substrate (100), the widths of the plurality of isolation rings increase sequentially by 0.5 mil.

6. The HDI circuit board according to claim 2, characterized in that: The invention also includes a plurality of first test PADs (310) and second test PADs (320), wherein the first test PADs (310) and the second test PADs (320) are both arranged on the surface of the substrate (100), the first test PADs (310) are electrically connected to the conductive layer (211), and the second test PADs (320) are electrically connected to the conductive rods (221).

7. The HDI circuit board according to claim 6, characterized in that: The first copper ring group (210) and the second copper ring group (220) are arranged along the width direction of the substrate (100); the first test PAD (310) is arranged on a side of the first copper ring group (210) away from the second copper ring group (220); and the second test PAD (320) is arranged on a side of the second copper ring group (220) away from the first copper ring group (210).

8. The HDI circuit board according to claim 6, characterized in that: The diameter of the first test PAD (310) or the second test PAD (320) is 0.5 mm to 1.5 mm.

9. The HDI circuit board according to claim 2, characterized in that: The diameter of the blind hole (120) is 2 mil to 6 mil.

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