Packaging substrate laser drilling method and packaging substrate

Abstract

The application provides a packaging substrate laser drilling method and a packaging substrate. The packaging substrate comprises a first copper layer, a dielectric layer and a second copper layer which are stacked in sequence. The method comprises the following steps: performing a first drilling operation by using a first laser energy to ablate a ring-shaped area on the first copper layer; performing a second drilling operation by using a second laser energy to remove a copper cover in the middle of the ring-shaped area and part of the dielectric layer, thereby forming a blind hole, wherein the second laser energy is smaller than the first laser energy; and performing a third drilling operation by using a third laser energy to remove the dielectric layer at the bottom of the blind hole until the second copper layer is exposed at the bottom of the blind hole, wherein the third laser energy is smaller than the second laser energy. The packaging substrate laser drilling method provided by the application can improve the laser drilling processing efficiency under the premise of meeting the quality requirements of laser drilling.

Description

Technical Field

[0001] This application relates to the field of packaging substrate processing technology, and in particular to a method for laser drilling of packaging substrates and a packaging substrate. Background Technology

[0002] LCP (Liquid Crystal Polymer) resin is a high-performance high-frequency circuit board material widely used in packaging substrates for 5G communications, millimeter-wave radar, and high-speed data transmission. LCP resin has poor thermal conductivity, making it prone to localized overheating. Additionally, its low melting point (below 280℃) allows it to easily melt into a liquid state. Laser drilling of LCP packaging substrates uses nanosecond lasers, and the high peak power generates instantaneous high temperatures within the resin, causing it to flow. This can easily lead to problems such as resin residue at the bottom of blind vias and poor bonding strength of the solder rings at the bottom of blind vias.

[0003] Currently, the industry standard practice is to use a low-energy, multi-stage laser drilling method to avoid quality problems caused by instantaneous overheating of the LCP resin. However, this method reduces the efficiency of laser drilling. Summary of the Invention

[0004] This application provides a laser drilling method for a packaging substrate and a packaging substrate, which can avoid quality problems caused by instantaneous overheating of the dielectric layer of the packaging substrate and improve the efficiency of laser drilling.

[0005] This application provides a method for laser drilling a packaging substrate, the packaging substrate comprising a first copper layer, a dielectric layer, and a second copper layer stacked sequentially, the method comprising:

[0006] A first drilling operation is performed using the first laser energy to ablate a ring-shaped area on the first copper layer;

[0007] A second drilling operation is performed using a second laser energy to remove the copper cap in the middle of the annular region and part of the dielectric layer, forming a blind hole. The second laser energy is less than the first laser energy.

[0008] A third drilling operation is performed using a third laser energy to remove the dielectric layer at the bottom of the blind hole until the second copper layer is exposed at the bottom of the blind hole. The third laser energy is less than the second laser energy.

[0009] In some embodiments, the second copper layer is formed with pads, and prior to the second drilling operation with the second laser energy, the method further includes:

[0010] Determine the type of pad at the bottom of the blind hole to be processed;

[0011] The second laser energy and the third laser energy are determined according to the type of the solder pad.

[0012] In some embodiments, the pad type includes independent pads, non-independent pads, pad combinations, and large copper pads;

[0013] The individual pads are surrounded by a closed etched area, which has no wiring connections.

[0014] The non-independent pads are connected to outward-extending lines;

[0015] The pad assembly includes multiple pads connected in sequence;

[0016] The copper surface area of ​​the large copper pad is greater than k times the area of ​​the blind via, where k is greater than or equal to 30.

[0017] In some embodiments, the second laser energy corresponding to the independent pad is less than the second laser energy corresponding to the non-independent pad, the second laser energy corresponding to the non-independent pad is less than the second laser energy corresponding to the pad combination, and the second laser energy corresponding to the pad combination is less than the second laser energy corresponding to the large copper pad.

[0018] In some embodiments, the third laser energy corresponding to the independent pad is less than the third laser energy corresponding to the non-independent pad, the third laser energy corresponding to the non-independent pad is less than the third laser energy corresponding to the pad combination, and the third laser energy corresponding to the pad combination is less than the third laser energy corresponding to the large copper pad.

[0019] In some embodiments, the laser scanning speed of the first drilling operation is less than the laser scanning speed of the second drilling operation, and the laser scanning speed of the second drilling operation is less than the laser scanning speed of the third drilling operation.

[0020] In some embodiments, the number of laser circumferential cuts in the first drilling operation is less than or equal to the number of laser circumferential cuts in the second drilling operation, and the number of laser circumferential cuts in the second drilling operation is less than the number of laser circumferential cuts in the third drilling operation.

[0021] In some embodiments, the laser frequency of the first drilling operation, the laser frequency of the second drilling operation, and the laser frequency of the third drilling operation are all the same.

[0022] In some embodiments, the dielectric layer is made of liquid crystal polymer resin.

[0023] This application embodiment also provides a packaging substrate, including a first copper layer, a dielectric layer, and a second copper layer stacked sequentially. A blind via is formed on the packaging substrate, the opening of the blind via is located in the first copper layer, and the bottom of the blind via exposes the second copper layer. The blind via is formed by any of the methods described above.

[0024] In the laser drilling method for packaging substrates according to embodiments of this application, the high temperature generated by the first drilling operation can be quickly conducted away by the first copper layer. Therefore, the first drilling operation can use a higher energy laser pulse to improve the laser drilling efficiency. The high temperature generated by the second and third drilling is mainly conducted away by the second copper layer at the bottom of the blind via. Since the second copper layer is located inside the packaging substrate, its heat dissipation performance is not as good as that of the first copper layer. Therefore, a lower energy laser pulse is used to avoid the resin in the dielectric layer from generating local high temperatures and undergoing rheological changes, thus avoiding quality problems caused by instantaneous overheating of the dielectric layer of the packaging substrate. Therefore, the laser drilling method for packaging substrates according to embodiments of this application can improve the laser drilling efficiency while meeting the laser drilling quality requirements. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the first structure of the packaging substrate according to an embodiment of this application.

[0027] Figure 2 This is a schematic diagram of a second structure of the packaging substrate according to an embodiment of this application.

[0028] Figure 3 This is a schematic diagram of the first process of the laser drilling method for the packaging substrate according to an embodiment of this application.

[0029] Figure 4 This is a schematic diagram of the packaging substrate structure after the first drilling operation in the embodiment of this application.

[0030] Figure 5 This is a schematic diagram of the annular area formed by the first drilling operation in the embodiment of this application.

[0031] Figure 6 This is a schematic diagram of the packaging substrate structure after the second drilling operation in the embodiment of this application.

[0032] Figure 7 This is a schematic diagram of the packaging substrate structure after the third drilling operation in the embodiment of this application.

[0033] Figure 8 This is a schematic diagram of the second process of the laser drilling method for the packaging substrate according to an embodiment of this application.

[0034] Figure 9 This is a schematic diagram of the individual pads of the packaging substrate according to an embodiment of this application.

[0035] Figure 10 This is a schematic diagram of the non-independent pads of the packaging substrate according to an embodiment of this application.

[0036] Figure 11 This is a schematic diagram of the pad assembly of the packaging substrate according to an embodiment of this application.

[0037] Figure 12 This is a schematic diagram of the large copper pads on the packaging substrate according to an embodiment of this application. Detailed Implementation

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0039] This application provides a packaging substrate. In some embodiments, the packaging substrate may be a flexible packaging substrate. (See reference...) Figure 1 , Figure 1 This is a schematic diagram of the first structure of the packaging substrate 100 according to an embodiment of this application.

[0040] The encapsulation substrate 100 includes a first copper layer 10, a dielectric layer 20, and a second copper layer 30 stacked sequentially. The dielectric layer 20 is made of resin. In some embodiments, the dielectric layer 20 is made of liquid crystal polymer (LCP) resin. In practical applications, LCP resin has poor thermal conductivity and is prone to local overheating. Additionally, the resin has a low melting point (less than 280°C) and easily melts into a liquid state.

[0041] In this embodiment, the second copper layer 30 has pads 31 formed thereon, and there may be multiple pads 31. In some embodiments, the first copper layer 10 may not have a circuit pattern formed thereon, while the second copper layer 30 has a circuit pattern formed thereon, which may include the aforementioned pads 31.

[0042] Blind vias 40 are formed on the packaging substrate 100, and there can be multiple blind vias 40. The opening of the blind via 40 is located in the first copper layer 10, and the bottom of the blind via 40 exposes the second copper layer 30. In practical applications, the blind via 40 can be positioned directly opposite the pad 31. The blind via 40 can undergo metallization treatment such as copper plating to form a metallized via, thereby achieving electrical connection between the pad 31 and other layers or electronic components.

[0043] In some embodiments, reference Figure 2 , Figure 2 This is a schematic diagram of a second structure of the packaging substrate 100 according to an embodiment of this application.

[0044] In this embodiment, a first copper layer 10, a dielectric layer 20, and a second copper layer 30 are sequentially stacked on both sides of the encapsulation substrate 100. A core layer 50 is disposed between the two inner second copper layers 30. In some embodiments, the core layer 50 may also be made of liquid crystal polymer (LCP). Blind vias 40 are formed on both sides of the encapsulation substrate 100.

[0045] This application also provides a laser drilling method for a packaging substrate, used to form the aforementioned blind via 40 on the packaging substrate 100. (See reference...) Figure 3 , Figure 3 This is a schematic diagram of a first step in the laser drilling method for a packaging substrate according to an embodiment of this application. The laser drilling method for the packaging substrate includes the following steps:

[0046] 210, Perform the first drilling operation with the first laser energy to ablate a ring-shaped area on the first copper layer;

[0047] 220, a second drilling operation is performed with the second laser energy to remove the copper cap and part of the dielectric layer in the middle of the annular area to form a blind hole. The second laser energy is less than the first laser energy.

[0048] 230. A third drilling operation is performed using the third laser energy to remove the dielectric layer at the bottom of the blind hole until the second copper layer is exposed at the bottom of the blind hole. The third laser energy is less than the second laser energy.

[0049] Please refer to the above. Figures 4 to 7 , Figure 4 This is a schematic diagram of the packaging substrate structure after the first drilling operation in an embodiment of this application. Figure 5 This is a schematic diagram of the annular region formed by the first drilling operation in the embodiment of this application. Figure 6 This is a schematic diagram of the packaging substrate structure after the second drilling operation in an embodiment of this application. Figure 7 This is a schematic diagram of the packaging substrate structure after the third drilling operation in the embodiment of this application.

[0050] First, the first drilling operation is performed using the first laser energy, such as... Figure 4 and Figure 5 As shown, an annular region is ablated on the first copper layer 10. The first copper layer 10 forms a large copper surface, and the annular region can be called a copper ring. There is a copper cap in the middle of the annular region, and the resin of the dielectric layer 20 is under the copper cap. During the first drilling operation, the high temperature generated by the laser will be rapidly conducted and dissipated by the outer large copper surface (first copper layer 10), so no local high temperature will be generated inside the resin and rheological changes will occur.

[0051] Subsequently, a second drilling operation is performed using the second laser energy, such as... Figure 6 As shown, the copper cap and part of the dielectric layer in the middle of the annular region are removed to form a blind hole. The second drilling operation can remove the copper cap and part of the resin under the copper cap, but resin remains at the bottom of the blind hole. The second drilling operation will not burn through the dielectric layer 20. During the second drilling operation, the high temperature generated by the resin in the dielectric layer 20 absorbing the laser is mainly conducted and dissipated by the copper layer at the bottom of the blind hole (i.e., the second copper layer 30). The energy of the second laser is less than that of the first laser.

[0052] Subsequently, a third drilling operation is performed using the third laser energy, such as... Figure 7 As shown, the dielectric layer 20 at the bottom of the blind hole is removed, i.e., the residual resin at the bottom of the blind hole is removed, until the second copper layer 30 is exposed at the bottom of the blind hole. At this point, the processing of the blind hole 40 is complete. During the third drilling operation, the high temperature generated by the resin in the dielectric layer 20 absorbing the laser is mainly conducted and dissipated through the copper layer (i.e., the second copper layer 30) at the bottom of the blind hole. The energy of the third laser is less than that of the second laser.

[0053] Understandably, the high temperature generated by the first drilling operation can be quickly conducted away by the outer large copper surface (first copper layer 10). Therefore, the first drilling operation can use a higher energy laser pulse to improve the efficiency of laser drilling. The high temperature generated by the second and third drilling operations is mainly conducted away by the copper layer at the bottom of the blind hole (i.e., the second copper layer 30). Since the second copper layer 30 is located inside the packaging substrate 100, its heat dissipation performance is not as good as that of the first copper layer 10. Therefore, a lower energy laser pulse is required to avoid the resin of the dielectric layer 20 from generating local high temperature and undergoing rheological changes. This can avoid quality problems caused by instantaneous overheating of the dielectric layer 20 of the packaging substrate.

[0054] Therefore, the laser drilling method for packaging substrates in this application embodiment can improve the laser drilling processing efficiency while meeting the laser drilling quality requirements.

[0055] In some embodiments, the laser for the first laser drilling can be set with the following parameters: frequency 250 kHz, energy 8~12 uJ, scanning speed 50~150 mm / s, and circumferential cutting 1~2 times. The laser for the second laser drilling can be set with the following parameters: frequency 250 kHz, energy 4~6 uJ, scanning speed 100~200 mm / s, and circumferential cutting 1~2 times. The laser for the third laser drilling can be set with the following parameters: frequency 250 kHz, energy 2~4 uJ, scanning speed 150~250 mm / s, and circumferential cutting 2~3 times. Therefore, it is possible to satisfy the condition that the energy of the second laser is less than that of the first laser, and the energy of the third laser is less than that of the second laser.

[0056] In some embodiments, reference Figure 8 , Figure 8 This is a schematic diagram of a second process for a laser drilling method for a packaging substrate according to an embodiment of this application. Prior to step 220, which involves performing a second drilling operation with a second laser energy, the method further includes the following steps:

[0057] 241. Determine the pad type at the bottom of the blind hole to be processed;

[0058] 242. Determine the corresponding second and third laser energies based on the pad type.

[0059] In practical applications, the second copper layer 30 forms multiple pads 31. These pads 31 can have different types, each with a different structure and area. Understandably, during the second and third drilling operations, the high temperature generated by the resin in the dielectric layer 20 absorbing the laser is mainly dissipated through conduction from the second copper layer 30 at the bottom of the blind via 40. Since the bottom of the blind via 40 faces the pads 31, the high temperature generated by the resin is primarily dissipated through conduction from the pads 31 at the bottom of the blind via 40. Different types of pads have different heat dissipation efficiencies. For example, larger pads dissipate heat faster, while smaller pads dissipate heat more slowly.

[0060] Therefore, before performing the second drilling operation, the type of pad at the bottom of the blind hole 40 to be processed can be determined first, and the corresponding second laser energy and third laser energy can be determined according to the pad type. This ensures that when performing the second drilling operation with the second laser energy and the third drilling operation with the third laser energy, the high temperature generated by the resin can be conducted out in time through the pad 31 at the bottom of the blind hole, thus avoiding the generation of local high temperature inside the resin and causing rheological changes.

[0061] In some embodiments, pad types include individual pads, non-independent pads, pad combinations, and large copper pads. (See reference) Figures 9 to 12 , Figure 9 This is a schematic diagram of the individual pads on the packaging substrate according to an embodiment of this application. Figure 10This is a schematic diagram of the non-independent pads of the packaging substrate according to an embodiment of this application. Figure 11 This is a schematic diagram of the pad assembly of the packaging substrate according to an embodiment of this application. Figure 12 This is a schematic diagram of the large copper pads on the packaging substrate according to an embodiment of this application.

[0062] Among them, such as Figure 9 As shown, the independent pad is surrounded by a closed etched area with no wiring connections; that is, there are no copper traces connecting the independent pad to the surrounding area. Independent pads can be independent circular (or irregular) pads. Independent pads have the lowest heat dissipation efficiency, and the resin above the pad is prone to high-temperature melting during laser drilling, leading to abnormal blind hole quality.

[0063] like Figure 10 As shown, non-independent pads have outward-extending traces, meaning there are connecting wires (copper traces) extending outwards from the pads. Non-independent pads are non-independent circular (or irregular) pads. During laser drilling, the wires connected to the non-independent pads participate in heat conduction, thus their heat dissipation efficiency is higher than that of independent pads. However, the overall heat dissipation efficiency is still lower. During laser drilling, the resin above the pads is more prone to high-temperature melting, leading to abnormal blind hole quality.

[0064] like Figure 11 As shown, a pad assembly comprises multiple pads connected in sequence. For example, a pad assembly can consist of 2 to 4 pads connected together, each pad being an independent circular (or irregular) pad. The pad assembly is surrounded by a closed etched area with no wiring connections. The pad assembly has high heat dissipation efficiency, and the resin above the pads is less likely to melt at high temperatures during laser drilling, thus reducing the risk of abnormal blind via quality.

[0065] like Figure 12 As shown, the large copper pad has a larger copper surface area. The bottom pad of the blind via is a large copper surface area, with its copper surface area being more than k times the area of ​​the blind via, where k is greater than or equal to 30. For example, in one example, k can be 30. The large copper pad has higher heat dissipation efficiency, and the resin above the pad is less likely to melt at high temperatures during laser drilling, thus preventing abnormal blind via quality.

[0066] In some embodiments, to avoid localized high temperatures and rheological changes within the resin during laser drilling, which could lead to abnormal blind hole quality, the second laser energy can be set as follows: the second laser energy corresponding to an independent pad is less than the second laser energy corresponding to a non-independent pad; the second laser energy corresponding to a non-independent pad is less than the second laser energy corresponding to a pad combination; and the second laser energy corresponding to a pad combination is less than the second laser energy corresponding to a large copper pad. That is, the higher the heat dissipation efficiency of the pad type, the greater its corresponding second laser energy.

[0067] In some embodiments, the third laser energy can be set as follows: the third laser energy corresponding to an independent pad is less than the third laser energy corresponding to a non-independent pad; the third laser energy corresponding to a non-independent pad is less than the third laser energy corresponding to a pad combination; and the third laser energy corresponding to a pad combination is less than the third laser energy corresponding to a large copper pad. That is, the higher the heat dissipation efficiency of the pad type, the greater its corresponding third laser energy.

[0068] In some embodiments, the laser scanning speed of the first drilling operation is lower than the laser scanning speed of the second drilling operation, and the laser scanning speed of the second drilling operation is lower than the laser scanning speed of the third drilling operation. In one example, the laser scanning speed of the first drilling operation is 50~150mm / s, for example, 150mm / s; the laser scanning speed of the second drilling operation is 100~200mm / s, for example, 200mm / s; and the laser scanning speed of the third drilling operation is 150~250mm / s, for example, 250mm / s.

[0069] In some embodiments, the number of laser circumferential cuts in the first drilling operation is less than or equal to the number of laser circumferential cuts in the second drilling operation, and the number of laser circumferential cuts in the second drilling operation is less than the number of laser circumferential cuts in the third drilling operation. In one example, the number of laser circumferential cuts in the first drilling operation is 1 to 2 times, for example, 1 time; the number of laser circumferential cuts in the second drilling operation is 1 to 2 times, for example, 1 time; and the number of laser circumferential cuts in the third drilling operation is 2 to 3 times, for example, 2 times.

[0070] In some embodiments, the laser frequency for the first drilling operation, the laser frequency for the second drilling operation, and the laser frequency for the third drilling operation are all the same. For example, in one example, the frequency can all be 250 kHz.

[0071] In a specific application example, the laser parameters for the second and third drilling operations can be set according to the table below:

[0072]

[0073] The four types of pads mentioned above are used to remove the remaining resin in the copper cap and blind holes using different laser parameters. When making the drilling tape, four different tools need to be used to laser process multiple blind holes on the packaging substrate according to the laser parameters set above. This can improve the laser processing efficiency while meeting the quality requirements of blind holes.

[0074] Understandably, in practical applications, a packaged substrate typically contains all four types of pads mentioned above. Compared to independent pads, non-independent pads can be laser-processed using higher laser energy and faster scanning speeds; compared to non-independent pads, pad combinations can be laser-processed using higher laser energy and fewer circumferential cuts; and compared to pad combinations, large copper pads can be laser-processed using higher laser energy and faster scanning speeds. Therefore, compared to traditional laser processing methods that use low laser energy and multiple processing steps for all pads, the embodiments of this application use different laser parameters for different types of pads. Non-independent pads, pad combinations, and large copper pads can all improve laser processing efficiency to a certain extent. Therefore, for a large number of pads on a packaged substrate, the embodiments of this application can greatly improve the overall laser processing efficiency of the packaged substrate. According to experimental data comparison, the laser drilling method of the embodiments of this application can improve the laser processing efficiency of blind holes on packaged substrates by 20%-30% compared to traditional laser drilling methods.

[0075] In the description of this application, it should be understood that terms such as “first” and “second” are used only to distinguish similar objects and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0076] The laser drilling method for the packaging substrate and the packaging substrate provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for laser drilling holes in a packaging substrate, characterized in that, The packaging substrate comprises a first copper layer, a medium layer and a second copper layer which are sequentially stacked, and the second copper layer is formed with a pad, and the method comprises: performing a first drilling operation with a first laser energy to ablate a ring-shaped area on the first copper layer; determining a pad type of a bottom of a blind hole to be processed; determining a corresponding second laser energy and a third laser energy according to the pad type; performing a second drilling operation with the second laser energy to remove a copper cover in the middle of the ring-shaped area and part of the medium layer, and form a blind hole, wherein the second laser energy is less than the first laser energy; performing a third drilling operation with the third laser energy to remove the medium layer at the bottom of the blind hole until the second copper layer is exposed at the bottom of the blind hole, wherein the third laser energy is less than the second laser energy.

2. The method of claim 1, wherein the laser drilling is performed by a laser beam having a wavelength of 193 nm to 355 nm. The pad type comprises an independent pad, a non-independent pad, a pad combination and a large copper surface pad; the independent pad is surrounded by a closed etching area without a circuit connection; the non-independent pad is connected with a circuit extending outwardly; the pad combination comprises a plurality of sequentially connected pads; the copper surface area of the large copper surface pad is greater than k times of the area of the blind hole, wherein k is greater than or equal to 30.

3. The method of claim 2, wherein the laser drilling is performed by a laser beam having a wavelength of 355 nm or less. The second laser energy corresponding to the independent pad is less than the second laser energy corresponding to the non-independent pad, the second laser energy corresponding to the non-independent pad is less than the second laser energy corresponding to the pad combination, and the second laser energy corresponding to the pad combination is less than the second laser energy corresponding to the large copper surface pad.

4. The method of claim 2, wherein the laser drilling is performed by a laser beam having a wavelength of 355 nm. The third laser energy corresponding to the independent pad is less than the third laser energy corresponding to the non-independent pad, the third laser energy corresponding to the non-independent pad is less than the third laser energy corresponding to the pad combination, and the third laser energy corresponding to the pad combination is less than the third laser energy corresponding to the large copper surface pad.

5. The method of claim 1 to 4, wherein, The laser scanning speed of the first drilling operation is less than the laser scanning speed of the second drilling operation, and the laser scanning speed of the second drilling operation is less than the laser scanning speed of the third drilling operation.

6. The method of claim 1 to 4, wherein, The number of laser ring cutting of the first drilling operation is less than or equal to the number of laser ring cutting of the second drilling operation, and the number of laser ring cutting of the second drilling operation is less than the number of laser ring cutting of the third drilling operation.

7. The method of claim 1 to 4, wherein, The laser frequency of the first drilling operation, the laser frequency of the second drilling operation and the laser frequency of the third drilling operation are the same.

8. The method of claim 1 to 4, wherein, The material of the medium layer is liquid crystal polymer resin.

9. A package substrate, characterized by, The packaging substrate comprises a first copper layer, a medium layer and a second copper layer which are sequentially stacked, and the packaging substrate is formed with a blind hole, the opening of the blind hole is located on the first copper layer, the bottom of the blind hole exposes the second copper layer, and the blind hole is formed by the method according to any one of claims 1 to 8.

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