Inner layer board of circuit board and circuit board

Abstract

The utility model discloses an inner layer board of a circuit board and the circuit board, the inner layer board of the circuit board is provided with a through hole in a first direction, the inner wall of the through hole is provided with a first metal layer, the inner wall of the through hole is provided with at least two grooves extending in the first direction at intervals, and the at least two grooves divide the first metal layer into groove lines. The metalized through hole is cut by laser to form the Z-direction slot line, the operation mode is simpler, the flatness is better, the size stability of the machined slot line is good, the requirement of a high-density product can be met, the Z-direction slot line replaces a via hole structure, the problem of via hole impedance falling is effectively solved, and the impedance consistency of a whole link is improved.

Description

Technical Field

[0001] This utility model relates to the field of circuit board manufacturing technology, and in particular to an inner layer board and a circuit board for a circuit board. Background Technology

[0002] PCB (Printed Circuit Board) is a type of circuit board. In PCB manufacturing, vias are required to provide electrical connections. To address the issue of impedance drop in vias, a new processing technology has emerged that uses Z-shaped slots to replace vias. This involves creating slots on the metallized hole walls using methods such as mechanical drilling, laser soldering, or etching to replace vias.

[0003] However, the mechanical drilling method involves filling the metallized trench with resin and then drilling through the metallized trench wall to form the trench line. This method is prone to short circuits due to unevenness issues. The laser tinning method involves plating another layer of tin on the metallized trench wall, then using a laser to etch away the tin layer in the non-trace areas of the hole wall to expose the copper. The exposed copper is then etched away, and finally, the trench line is exposed by desoldering. This method is complex, and the tin layer is relatively thin, making it difficult for the laser to completely etch away the tin on the hole wall, easily leading to short circuits. Etching methods cannot apply a wet film to the trench wall, require the trench to be inclined, and the trench size is relatively large, making it difficult to meet the needs of current high-density products. Utility Model Content

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an inner layer board for a circuit board, which utilizes laser cutting of metallized through holes to form Z-direction grooves. The processed grooves have good dimensional stability, which can meet the needs of high-density products. The Z-direction grooves replace via structures, effectively solving the problem of via impedance drop.

[0005] This utility model further proposes a circuit board.

[0006] According to the first aspect of the present invention, the inner layer board of the circuit board has a through hole in a first direction, a first metal layer is disposed on the inner wall of the through hole, and at least two grooves extending in the first direction are disposed at intervals on the inner wall of the through hole, the at least two grooves dividing the first metal layer into groove lines.

[0007] According to the embodiment of the present invention, the inner layer of the circuit board uses laser cutting of metallized through holes to form Z-direction grooves. The operation is simpler, the flatness is better, and the dimensional stability of the processed grooves is good, which can meet the needs of high-density products. In addition, the Z-direction grooves replace the via structure, effectively solving the problem of via impedance drop and improving the impedance consistency of the entire link.

[0008] According to some embodiments of this utility model, the length of the through hole is h1, the width of the through hole is h2, and h1 and h2 satisfy the relationship: h1≥2h2.

[0009] According to some embodiments of this utility model, the distance between two adjacent grooves is h3, and h3 satisfies the relationship: 40um≤h3≤60um.

[0010] According to some embodiments of the present invention, the thickness of the first metal layer is h4, and h4 satisfies the relationship: 14um≤h4≤22um.

[0011] According to some embodiments of the present invention, the groove is obtained by laser cutting, and the laser cutting range is composed of a first groove and a second groove in the second direction. The first groove has a dimension of h5 in the second direction, and the second groove has a dimension of h6 in the second direction. h5 and h6 satisfy the following relationship: h5 < h6, h6 ≥ 80 μm.

[0012] According to some embodiments of the present invention, the inner layer plate is provided with a second metal layer on both sides in a first direction, and the second metal layer protrudes relative to the groove line at the edge of the through hole.

[0013] According to some embodiments of this utility model, the second metal layer protrudes by an amount h7 relative to the groove line, and h7 satisfies the relationship: h7≥50um.

[0014] According to some embodiments of the present invention, the thickness of the second metal layer is h8, and h8 satisfies the relationship: h8≥15um.

[0015] The circuit board according to a second aspect of the present invention includes the inner layer board.

[0016] Compared to traditional methods, this embodiment utilizes laser cutting of metallized through-holes to form Z-direction grooves, which is simpler to operate, has better flatness, and produces grooves with good dimensional stability, meeting the needs of high-density products. Furthermore, the Z-direction grooves replace via structures, effectively solving the problem of via impedance drop and improving impedance consistency across the entire link.

[0017] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0019] Figure 1 This is a schematic diagram of the structure of the inner layer plate according to an embodiment of the present utility model. Figure 1 ;

[0020] Figure 2 This is a schematic diagram of the structure of the inner layer plate according to an embodiment of the present utility model. Figure 2 ;

[0021] Figure 3 This is a schematic diagram of the structure of the inner layer plate according to an embodiment of the present utility model. Figure 3 .

[0022] Figure label:

[0023] 10. Through hole; 11. First metal layer; 12. Trench; 13. Second metal layer; 14. Groove line. Detailed Implementation

[0024] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0025] The following is for reference. Figures 1-3 The present invention describes the inner layer board of a circuit board according to an embodiment of the present invention, and also proposes a circuit board.

[0026] Reference Figure 1-3 As shown, the inner layer board of the circuit board of this utility model embodiment has a through hole 10 in the first direction. The inner wall of the through hole 10 is provided with a first metal layer 11. At least two grooves 12 extending in the first direction are provided at intervals on the inner wall of the through hole 10. The at least two grooves 12 divide the first metal layer 11 into groove lines 14.

[0027] The processing steps for groove line 14 are as follows: inner layer board to be processed - micro etching - mechanical drilling - desmearing - electroplating - making groove line 14 - two horizontal desmearing - resin plugging - electroplating copper coating - pattern etching - lamination - laser drilling - electroplating - pattern etching - completed inner layer board.

[0028] Specifically, the inner layer board to be processed is first micro-etched. Micro-etching refers to removing a thin layer on the copper surface through chemical methods to clean and roughen the copper surface and improve the adhesion of subsequent processes. The thickness of the copper after micro-etching is controlled within the range of 10±1μm.

[0029] The inner layer board being manufactured can be a single core board or an inner layer board made by pressing together multiple core boards.

[0030] Through holes 10 are machined by mechanical drilling. The diameter of each hole drilled by mechanical drilling is the same as the width of the through hole 10 to be machined. In this embodiment, the center distance between the holes made by the drilling tool is 50μm. After multiple mechanical drillings, the length of the superimposed holes is the same as the length of the through hole 10 to be machined, thus forming the through hole 10.

[0031] The inner layer board of the drilled through hole 10 is first de-drilled. The de-drilling step is mainly used to remove dirt and residues generated during the mechanical drilling process. These residues usually include resin, glass fiber and other materials. If they are not removed, they will affect the metallization quality of the hole wall, and thus affect the performance and reliability of the circuit board.

[0032] After descaling, electroplating is performed, which deposits a layer of metal, usually copper, on the inner wall of the trench 12. This is the first metal layer 11, which provides electrical connection and mechanical strength.

[0033] After electroplating, groove lines 14 are fabricated. Grooves are then created using laser cutting. Grooves 12 extend in the first direction, and adjacent grooves 12 divide the first metal layer 11 into groove lines 14. (Refer to...) Figure 1 As shown, Figure 1 Two groove lines 14 are formed in a single through hole 10, and a single through hole 10 can also form a groove line 14.

[0034] Specifically, the first direction can be the left or right direction.

[0035] Furthermore, the cutting path of the laser cutting equipment is rectangular, and the size of the rectangle can be appropriately increased as the width and diameter of the groove 12 increase. Moreover, the length of the cutting path is equal to the spacing of the groove lines 14, that is, the length of the cutting path depends on the length of the through hole 10 and the number of groove lines 14.

[0036] After the groove line 14 is formed, it needs to be de-drilled twice to remove dirt and residue, and then resin plugging is performed. Resin plugging can prevent the through hole 10 from being contaminated by impurities during subsequent production, and can also improve the mechanical strength of the inner layer board, reduce stress concentration around the through hole 10, improve the reliability of welding, and improve the surface flatness of the inner layer board.

[0037] After electroplating with copper, the inner layer board undergoes pattern etching, lamination, laser drilling, electroplating again, and pattern etching to form the final product. This inner layer board has a simpler processing flow, better flatness, and good dimensional stability of the processed grooves 14, which can meet the needs of high-density products.

[0038] Pattern etching refers to the use of chemical methods to remove unwanted copper foil to form circuit patterns, while lamination refers to the bonding of multiple layers of prefabricated inner circuit boards, insulating layers and copper foil layers together under high temperature and high pressure to form a whole.

[0039] Therefore, using laser cutting of metallized through holes 10 to form Z-direction groove lines 14 is a simpler operation method with better flatness. The processed groove lines 14 have good dimensional stability, which can meet the needs of high-density products. Furthermore, the Z-direction groove lines 14 replace the via structure, effectively solving the problem of via impedance drop and improving the impedance consistency of the entire link.

[0040] Reference Figure 1-3 As shown, the length of the through hole 10 is h1, and the width of the through hole 10 is h2. h1 and h2 satisfy the relationship: h1≥2h2. That is, the length of the through hole 10 is not less than twice the width of the through hole 10, and the minimum machinable width of the through hole 10 is 0.2mm.

[0041] Reference Figure 1-3 As shown, the distance between two adjacent trenches 12 is h3, and h3 satisfies the relationship: 40um ≤ h3 ≤ 60um. That is, the distance between two adjacent trenches 12 is not less than 40um and not more than 60um. The distance between two adjacent trenches 12 is the length of the slot line 14. By controlling the length of the slot line 14 to be between 40-60um, the integrity of signal transmission can be guaranteed, and it has good electrical performance and mechanical strength.

[0042] Reference Figure 1-3 As shown, the thickness of the first metal layer 11 is h4, which satisfies the relationship: 14um ≤ h4 ≤ 22um. That is, the thickness of the first metal layer 11 is not less than 14um and not more than 22um. In other words, after electroplating, the copper thickness of the hole wall of the through hole 10 is controlled within the range of 18±4μm.

[0043] In addition, the thickness of the copper surface is no more than 33μm.

[0044] Reference Figure 1-3 As shown, the groove 12 is obtained by laser cutting. The laser cutting range in the second direction is composed of a first groove 12 and a second groove 12. The dimension of the first groove 12 in the second direction is h5, and the dimension of the second groove 12 in the second direction is h6. h5 and h6 satisfy the relationship: h5 < h6, h6 ≥ 80 μm. Specifically, the second direction can be the vertical direction. The groove 12 can be cut in two stages to avoid generating too much heat during a single cutting process, which could lead to material deformation or scorching. Moreover, segmented cutting can ensure that each layer of material is cut in place, avoiding interlayer separation and improving the accuracy of the groove line 14.

[0045] Furthermore, the width of the laser-cut rectangle is not less than 130μm, the dimension h5 of the first groove 12 in the second direction is fixed at 50μm, and the dimension h6 of the second groove 12 in the second direction is ≥80μm.

[0046] The laser cutting of the groove 14 requires a high-precision laser cutting device with a pulse width of picoseconds or higher. The laser source can be ultraviolet or green laser, which can directly process copper. The groove 12 is cut into the inner layer plate by the laser cutting device. Laser cutting can achieve very fine cutting, with an accuracy typically within 0.1 mm. It is suitable for processing complex shapes and precision parts. The cut after laser cutting is smooth and burr-free, reducing the need for subsequent processing and improving the appearance quality of the product. It can also significantly improve production efficiency, making it particularly suitable for mass production and continuous processing. It has a high degree of automation, is applicable to a wide range of materials, and can reduce the mechanical stress of the inner layer plate.

[0047] Reference Figure 1-3 As shown, the inner layer plate has a second metal layer 13 on both sides in the first direction, and the second metal layer 13 protrudes relative to the groove line 14 at the edge of the through hole 10. Specifically, the second metal layer 13 is electroplated copper cover. Electroplated copper cover can enhance conductivity and improve mechanical strength. The uniform copper layer after electroplating can provide a better welding surface, improve welding quality and reliability, and the increased copper thickness after electroplating further ensures the conductivity and mechanical strength of the electrical connection.

[0048] Reference Figure 1-3 As shown, the second metal layer 13 protrudes by an dimension h7 relative to the groove line 14, where h7 satisfies the relationship: h7 ≥ 50 μm. The thickness of the second metal layer 13 is h8, where h8 satisfies the relationship: h8 ≥ 15 μm. In other words, the copper overlay must cover the entire length of the groove line 14 by at least 50 μm, and the copper overlay thickness must be at least 15 μm. This provides better conductivity and mechanical strength, a better welding surface, improved welding quality and reliability, and reduces the occurrence of short circuits.

[0049] According to a second aspect of the present invention, a circuit board includes an inner layer board. The circuit board is a plate-like structure for supporting and connecting electronic components. It is composed of a non-conductive substrate and a conductive copper foil layer, i.e., the inner layer board. Circuit patterns are formed on the copper foil layer through processes such as etching and printing. The circuit board can realize electrical connection and signal transmission between electronic components. The circuit board with this inner layer board can meet the needs of high-density products.

[0050] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0051] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0052] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An inner layer board of a circuit board, characterized by, The inner layer plate is provided with a through hole (10) in the first direction, an inner wall of the through hole (10) is provided with a first metal layer (11), at least two grooves (12) extending in the first direction are provided on the inner wall of the through hole (10) at intervals, and the at least two grooves (12) separate the first metal layer (11) into slot lines.

2. The inner layer board of claim 1, wherein The length of the through hole (10) is h1, the width of the through hole (10) is h2, and h1 and h2 satisfy the relationship: h1≥2h2.

3. The inner layer board of Claim 1, wherein The distance between two adjacent grooves (12) is h3, and h3 satisfies the relationship: 40um≤h3≤60um.

4. The inner layer board of Claim 1, wherein The thickness of the first metal layer (11) is h4, and h4 satisfies the relationship: 14um≤h4≤22um.

5. The inner layer board of Claim 1, wherein The groove (12) is obtained by laser cutting, the laser cutting range in the second direction is composed of a first groove (12) and a second groove (12), the size of the first groove (12) in the second direction is h5, the size of the second groove (12) in the second direction is h6, h5 and h6 satisfy the relationship: h5 6. The inner layer board of Claim 1, wherein The inner layer plate is provided with a through hole (10) in the first direction, an inner wall of the through hole (10) is provided with a first metal layer (11), at least two grooves (12) extending in the first direction are provided on the inner wall of the through hole (10) at intervals, and the at least two grooves (12) separate the first metal layer (11) into slot lines.

7. The inner layer board of claim 6, wherein The size of the second metal layer (13) protruding relative to the slot line is h7, and h7 satisfies the relationship: h7≥50um.

8. The inner layer board of Claim 6, wherein The thickness of the second metal layer (13) is h8, and h8 satisfies the relationship: h8≥15um.

9. A circuit board, characterized by Comprise: The inner layer plate of any one of claims 1-8.

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