Printed circuit board with X-shaped hole

Abstract

The utility model discloses a printed circuit board with X-shaped holes, and belongs to the technical field of PCBs. Comprising a printed circuit substrate, an odd number of pieces of glass cloth are adopted in a substrate body, a large window and a small window are formed in the two faces of the substrate, a laser drilling machine is adopted for machining X-shaped through holes from the small laser window face in a laser mode, one-time laser drilling is achieved, and the printed circuit substrate does not need to be turned over for secondary machining. The laser drilling device has the advantages that two-time drilling in the prior art is replaced with one-time laser drilling, and the problem of deviation of the upper aperture and the lower aperture is fundamentally solved. The center deviation precision of the upper hole and the lower hole in the X-shaped hole formed through the machining method can be controlled within 25 micrometers, the CPK value is larger than 1.33, and a series of copper plating quality problems caused by too large deviation of the upper hole and the lower hole can be avoided.

Description

Technical Field

[0001] This utility model relates to the field of printed circuit board technology, and in particular to a printed circuit board containing an X-shaped hole. Background Technology

[0002] Currently, consumer terminals, represented by mobile phones and smart wearable products, have increasingly higher demands for thinner and higher-density components. To improve product reliability, product designs often use X-shaped holes instead of blind holes in the core board layer to avoid the risk of failure at the bottom of blind holes.

[0003] X-hole machining typically employs a two-stage laser drilling process, requiring two alignments. This carries the risk of insufficient precision in the upper and lower holes, excessive deviation in the center distance between them, and in severe cases, complete misalignment of the upper and lower holes. When significant deviations occur, there is a risk of the X-hole being too small or misaligned, resulting in voids or breakage in the copper plating layer. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, this application proposes a printed circuit board with X-shaped holes to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, this utility model provides the following technical solution:

[0006] A printed circuit board with X-shaped holes includes a printed circuit board substrate, which includes an insulating dielectric layer and a copper foil layer. The surface of the printed circuit board substrate is patterned by transferring a pattern to form laser window patterns of different sizes. The X-shaped holes are formed by laser drilling from small laser windows using a laser drilling machine, achieving laser drilling in one step without having to flip the printed circuit board substrate for a second processing.

[0007] As a further technical solution of this utility model: the thickness of the printed circuit board needs to be ≤0.15mm, the thickness of the insulating dielectric layer needs to be ≤0.128mm, and the insulating dielectric layer is a single sheet of glass cloth or an odd number of sheets of glass cloth.

[0008] As a further technical solution of this utility model: the diameter difference between the large and small laser windows is 5-20μm, the diameter range of the small laser window is 47-97μm, and the diameter range of the large laser window is 57-107μm.

[0009] As a further technical solution of this utility model: the X-shaped hole processed by laser in one operation has an aperture diameter of 2-2.5mm, a pulse width of 10-15μs, an energy of 6-11W, and a number of laser pulses of 1-2.

[0010] As a further technical solution of this utility model: the upper and lower X-shaped holes of the X-shaped through hole have a diameter of 60-110μm, the waist hole diameter ranges from 48-88μm, and the hole center deviation of the upper and lower holes is ≤25μm.

[0011] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0012] This invention first fabricates circuitry on a printed circuit board (PCB) to create laser windows. The diameters of the two laser windows differ by 10 μm. Then, a laser drilling machine is used to laser-drill X-shaped through-holes from the smaller laser window, achieving single-stage laser drilling without flipping the PCB for a second processing step. The X-shaped holes are then filled using copper plating, resulting in high-precision X-shaped holes. This single-stage laser drilling avoids the alignment deviations associated with two separate laser drilling operations, achieving high-precision X-shaped holes. The center deviation accuracy of the upper and lower holes in the resulting X-shaped holes can be controlled within 25 μm, with a CPK value > 1.33, avoiding a series of copper plating quality problems caused by excessive deviation between the upper and lower holes. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the printed circuit board of this utility model;

[0014] Figure 2 This is a schematic diagram of the windowing process of the printed circuit board of this utility model;

[0015] Figure 3 This is a schematic diagram of the drilling process of the printed circuit board of this utility model.

[0016] In the diagram: 1-PCB double-sided board, 2-PCB double-sided board, 3-PCB double-sided board, 110-insulating dielectric layer, 111-copper foil layer, 112-copper foil layer, 113-dry film pattern layer, 114-dry film pattern layer, 115-electroplated copper layer, 1a-upper part not covered by dry film pattern layer, 2a-lower part not covered by dry film pattern layer, 1b-upper laser window, 2b-lower laser window, 1c-upper X-hole, 2c-lower X-hole. Detailed Implementation

[0017] The technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0018] like Figures 1 to 3As shown, a method for manufacturing a printed circuit board with X-shaped holes includes the following steps:

[0019] Step 1: Provide a printed circuit board, which includes an insulating dielectric layer and a copper foil layer. The thickness of the printed circuit board must be ≤0.15mm, and the insulating dielectric layer is a single sheet of glass cloth.

[0020] Step 2: Apply a film to the surface of the printed circuit board to form a dry film layer on the surface of the copper foil layer.

[0021] Step 3: Expose the dry film layer and the dry film layer to form a dry film pattern layer. After exposure, develop the dry film pattern layer and remove the unexposed dry film pattern layer with a chemical solution to expose the parts not covered by the dry film pattern layer. The diameter of 1a is 10 μm larger than the diameter of 2a.

[0022] Step 4: Use a chemical solution to remove the upper part of the copper foil layer that is not covered by the dry film pattern layer to form an upper laser window, and remove the lower part of the copper foil layer that is not covered by the dry film pattern layer to form a laser window.

[0023] Step 5: Remove the dry film pattern layer using a chemical solution.

[0024] Step Six: Place the printed circuit board on the CO2 laser processing table. Place a table fixture between the printed circuit board and the CO2 laser processing table. Perform CO2 laser through-hole drilling on the lower laser window of the insulating dielectric layer and penetrate the insulating layer. Since the glass cloth is relatively difficult to ablate and is in the middle, an X-shaped through hole is formed. Depending on the thickness of the middle layer of the printed circuit board, the processing aperture diameter is 2-2.5mm, the pulse width is 10-15μs, the energy is 6-11W, and the number of shots is 1-2.

[0025] Step 7: Apply copper plating to the walls and surfaces of the X-shaped vias to connect the upper and lower surfaces of the intermediate layer of the printed circuit board to form conductive vias. Electroplating is then applied to fill the vias, with a depression of ≤15μm and a copper plating thickness of 15-25μm.

[0026] Step 8: After pattern transfer, the required pattern is created on the upper and lower copper foil layers, and the next process is carried out as needed.

[0027] As described above, this utility model first produces a double-layer dry film on a double-sided PCB of a certain thickness, then forms a laser window through pattern exposure, removes the dry film, and uses a laser drilling machine to drill through the upper and lower laser windows with single-sided laser processing to form an X-shaped hole. At the same time, copper-plated conductive X-shaped holes are produced, and the X-shaped holes are filled by electroplating.

[0028] like Figures 1 to 3As shown, preferably, the thickness of the printed circuit board is ≤0.15mm, so that high-precision X-shaped holes can be achieved by laser single-sided drilling, reducing the deviation of the upper and lower hole centers.

[0029] like Figures 1 to 3 As shown, the thickness of the insulating dielectric layer is ≤128μm, and it must be a single sheet or an odd number of sheets of glass cloth. In this way, the glass fiber cloth of the insulating dielectric layer is located in the middle area. When the laser drills a hole on one side, since the glass fiber is difficult to ablate, the middle hole diameter is smaller than the upper and lower hole diameters, about 70-90%. The X-shaped hole has a good waist and forms a through hole with a similar "X" shape.

[0030] like Figures 1 to 3 As shown, the diameter of the window layer is 10 μm larger than that of the window layer, and the diameter range of the window layer is 47-97 μm and the diameter range of the window layer is 57-107 μm. In this way, when drilling holes on one side with a laser, the laser will not ablate the copper foil layer on the surface due to pattern deviation, forming reflection and resulting in poor hole shape.

[0031] like Figures 1 to 3 As shown, preferably, the laser processing surface is a laser window with an insulating dielectric layer. This avoids the copper foil layer on the surface being burned during single-sided laser drilling, which would cause reflection and result in poor hole shape.

[0032] like Figures 1 to 3 As shown, preferably, the center deviation of the upper and lower holes of the X-shaped hole is ≤25μm, and the diameter of the X-shaped hole is in the range of 60-110μm, and the waist diameter is in the range of 48-88μm. In this way, it can be ensured that the smaller diameter of the middle hole is filled first when electroplating the X-shaped hole, and the electroplating voids are avoided.

[0033] like Figures 1 to 3 As shown, preferably, a special table fixture needs to be placed between the laser drilling machine and the printed circuit board. In this way, during step five, it is easy to protect the laser drilling machine table surface and ensure the flatness of the board and the integrity of the laser drilling machine table surface.

[0034] like Figures 1 to 3 As shown, preferably, the laser drilling machine processes X-shaped through holes with an aperture diameter of 2-2.5mm, a pulse width of 10-15μs, an energy of 6-11W, and a number of 1-2 pulses. This ensures the shape of the X-shaped hole and allows for priority filling of the smaller diameter hole during electroplating, thus avoiding electroplating voids.

[0035] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention.

[0036] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment have been appropriately combined to form other embodiments that are easy for those skilled in the art to understand.

Claims

1. A printed circuit board having X-holes, comprising a printed circuit substrate, characterized by: The printed circuit board includes an insulating medium layer and a copper foil layer, the surface of the printed circuit board is subjected to pattern transfer to form a size laser window pattern, and an X-shaped hole is formed by laser machining from a small laser window surface to realize one-time laser drilling without the need to turn over the printed circuit board for second-time processing.

2. A printed circuit board containing X-holes according to claim 1, characterized in that, The thickness of the printed circuit board is ≤0.15 mm, the thickness of the insulating medium layer is ≤0.128 mm, and the insulating medium layer is single or odd glass cloth.

3. The printed circuit board containing X-holes according to claim 1, wherein, The diameter difference between the large and small laser windows is 5-20 μm, the small laser window diameter ranges from 47 to 97 μm, and the large laser window diameter ranges from 57 to 107 μm.

4. The printed circuit board containing X-holes according to claim 1, wherein, The one-time laser machining of the X-shaped hole has an aperture diameter of 2-2.5 mm, a pulse width of 10-15 μs, an energy of 6-11 W, and a number of shots of 1-2.

5. The printed circuit board containing X-holes according to claim 1, wherein, The X-shaped hole is a through hole, the upper and lower hole diameters of the X-shaped hole are 60-110 μm, the waist hole diameter ranges from 48 to 88 μm, and the hole center deviation of the upper and lower holes is ≤25 μm.

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