PCB (Printed Circuit Board) substrate with bottom copper gold-plated blind groove and preparation method thereof

Abstract

The invention provides a PCB substrate with a bottom copper gold-plated blind groove and a preparation method thereof, and the PCB substrate with the bottom copper gold-plated blind groove comprises the components of pasting layer resin which is provided with a blind groove region which is recessed from the surface of the pasting layer resin, and the side wall of the blind groove region exposes the material of the pasting layer resin; the area, except the blind groove area, of the front face of the pasting layer resin is at least partially covered with the dry ink; the bottom copper is arranged at the bottom of the blind slot region; the upper surface of the bottom copper is provided with a top surface groove, the top surface groove is filled with the bottom gold plating, and the top surface of the bottom gold plating is flush with the opening surface of the top surface groove. Therefore, the side wall of the blind groove area is made of the original material of the pasting layer resin, the insulativity is good, only the bottom of the blind groove area is made of the gold-plated material, and the conductivity is good. And the bottom of the blind slot region is in a composite form of'gold on the upper part and copper on the lower part ', and the gold plating effect is good.

Description

Technical Field

[0001] The present application relates to the field of printed circuit boards, and in particular to a PCB substrate having a bottom copper gold-plated blind groove and a preparation method thereof. Background Art

[0002] With the requirement of high-speed communication, the chip needs to be embedded in the substrate during the packaging process. Therefore, a blind groove needs to be opened during the substrate processing, and gold plating is performed on the bottom of the blind groove. This method is called blind groove process (or Cavity process). The blind groove bottom copper gold plating process is: pattern formation, solder mask, blind groove process, gold plating (nickel gold or nickel palladium gold).

[0003] The traditional blind slot machining after solder mask cannot meet the bottom copper gold plating requirements of the blind slot, while laser processing (or laser processing) can achieve the bottom copper gold plating requirements. Figure 3 This is a schematic diagram of the structure of a copper-plated gold base. Figure 3 The gold-plated area 5 in the circuit mainly includes two parts, one part is the bottom gold 51 located at the bottom of the blind groove. In addition, if the gold-plating effect is not good and the gold-plated area is not accurate, the PCB substrate may fail in a high temperature and high humidity environment. Summary of the invention

[0004] In view of the above-mentioned state of the prior art, this application is made. In a first aspect, the purpose of this application is to provide a PCB substrate with a bottom copper gold-plated blind groove.

[0005] The technical solution adopted by the present application to solve its technical problems includes: a PCB substrate with a bottom copper gold-plated blind groove, including: a laminate resin, the laminate resin has a blind groove area recessed from its surface, and the side wall of the blind groove area exposes the material of the laminate resin; dry ink, the area on the front side of the laminate resin except the blind groove area is at least partially covered with the dry ink; bottom copper, the bottom of the blind groove area is provided with the bottom copper; bottom gold plating, the upper surface of the bottom copper is provided with a top surface groove, the top surface groove is filled with the bottom gold plating, and the top surface of the bottom gold plating is flush with the opening surface of the top surface groove.

[0006] As a further improvement of the present application, when observed along the depth direction of the blind groove area, the bottom surface area of ​​the blind groove area is equal to the top surface area of ​​the bottom gold plating, the top surface area of ​​the bottom copper is larger than the top surface area of ​​the bottom gold plating, and the bottom copper has an expansion portion inserted into the interior of the lamination resin.

[0007] As a further improvement of the present application, the depth of the blind groove area is greater than half of the thickness of the laminating resin.

[0008] As a further improvement of the present application, the depth value of the blind groove area is smaller than the width value of the blind groove area.

[0009] As a further improvement of the present application, the thickness of the bottom gold plating is less than half of the thickness of the bottom copper.

[0010] As a further improvement of the present application, the front surface of the laminating resin around the opening of the blind groove area also has an exposed area not covered by the dry ink.

[0011] As a further improvement of the present application, the expansion dimension of the expansion portion in the width direction of the blind groove area is greater than the dimension of the exposed area in the width direction of the blind groove area.

[0012] As a further improvement of the present application, a soldering pad is further arranged between the dry ink and the laminating resin; the laminating resin not covered by the soldering pad exists around the opening of the blind groove area; and the soldering pad not covered by the dry ink exists around the opening of the blind groove area.

[0013] As a further improvement of the present application, the angle between the side wall of the blind groove area and the bottom surface of the blind groove area ranges from 90° to 110°; in the width direction of the blind groove area, the lateral dimension from the opening edge of the pasting resin corresponding to the opening of the blind groove area to the bottom surface edge of the blind groove area is not greater than 2 mil; in the width direction of the blind groove area, the lateral dimension from the opening edge of the pad corresponding to the opening of the blind groove area to the bottom surface edge of the blind groove area is not greater than 4 mil.

[0014] In the second aspect, a method for preparing a PCB substrate with a bottom copper gold-plated blind groove is provided. The method is used to manufacture the PCB substrate with a bottom copper gold-plated blind groove of the present application, comprising: step S1, laser processing: processing the blind groove area on the surface of the PCB board; step S2, preliminary cleaning: cleaning the dirt generated by the laser processing; step S3, mid-section cleaning: using charged gas to modify the surface of the blind groove area after the laser processing; step S4, terminal cleaning: washing and cleaning the blind groove area after the charged gas treatment; step S5, gold plating: gold plating the bottom copper.

[0015] As a further improvement of the present application, the laser utilizes laser thermal effect, and the thermal melting effect of the laser on the copper material is smaller than the thermal melting effect on the bonding resin; the laser thermally melts the glass fibers in the bonding resin and vaporizes the resin, and the laser thermally melts the blind groove area to a specified depth, thereby achieving the molding of the blind groove area.

[0016] As a further improvement of the present application, within the same unit time and the same unit area, the degree of cleaning of the surface of the PCB board by the charged gas is greater than the preliminary cleaning; the charged gas is a gas with a negative charge.

[0017] As a further improvement of the present application, the preliminary cleaning and the terminal cleaning remove the surface attachments of the PCB board; the water pressure of the terminal cleaning is not less than 0.6MPa; and the PCB board is contacted and transported at three points during the water washing cleaning.

[0018] As a further improvement of the present application, there is a pre-step before step S1; the pre-step includes: pre-step S01, image formation: forming a circuit pattern on the PCB board; pre-step S02, solder resist: applying solder resist ink on the PCB board.

[0019] As a further improvement of the present application, the gold plating in step S5 is a pretreatment and nickel-palladium-gold plating, and an inspection step is further provided after step S5; step S501, pretreatment; chemically corroding the bottom copper to remove oxides, stains and uneven parts on the surface of the bottom copper; step S502, nickel-palladium-gold plating; first plating a layer of nickel on the surface of the bottom copper, then plating a layer of palladium, and finally plating a layer of gold; the inspection step includes: visually observing the PCB board and observing it using a microscope, and comparing the defective photos and defective microscope images of the PCB board.

[0020] The beneficial effects of the PCB substrate with bottom copper gold-plated blind groove of the present application include: the side wall of the blind groove area is the original material of the laminate resin, only the bottom of the blind groove area is gold-plated and conductive, and the resin of the side wall of the blind groove area is non-conductive, which ensures the insulation of the PCB product in this specified direction and is not easy to fail in high temperature and high humidity environment. In addition, the bottom of the blind groove area is a composite form of "gold on top and copper on bottom", and the bottom copper provides sufficient gold-plating area and sufficient gold-plating thickness for the bottom gold plating, and also provides a stable gold-plating area, ensuring that the blind groove area has and only has gold plating at the bottom, and the gold plating effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 It is a structural schematic diagram of an embodiment of a PCB substrate with a bottom copper gold-plated blind groove of the present application;

[0023] Figure 2 It is a process flow chart of an embodiment of a PCB substrate with bottom copper gold-plated blind groove of the present application;

[0024] Figure 3 It is a schematic diagram of the structure of a base copper plated with gold;

[0025] Figure 4 This is a microscope image of a cross section of a blind groove area after laser processing of an embodiment of a PCB substrate having a bottom copper gold-plated blind groove of the present application;

[0026] Figure 5 It is a microscope picture of the cross section of the blind groove area after preliminary cleaning, mid-section cleaning, and terminal cleaning of an embodiment of the PCB substrate with bottom copper gold-plated blind groove of the present application;

[0027] Figure 6 is a photograph of a blind groove area of ​​an embodiment of a PCB substrate with a bottom copper gold-plated blind groove of the present application;

[0028] Figure 7 This is a microscope image of a blind groove area slice of an embodiment of a PCB substrate with a bottom copper gold-plated blind groove of the present application;

[0029] Figure 8 It is a process problem diagram in the field of PCB board processing;

[0030] Fig. 9 It is a process flow chart of an embodiment of a method for preparing a PCB substrate with a bottom copper gold-plated blind groove of the present application;

[0031] Fig.10 It is a structural schematic diagram of an embodiment of a PCB substrate with a bottom copper gold-plated blind groove of the present application;

[0032] Fig.11 It is a microscope image of a blind groove area of ​​an embodiment of a PCB substrate with a bottom copper gold-plated blind groove of the present application;

[0033] Fig.12 It is a microscope image of a blind groove area of ​​an embodiment of a PCB substrate with a bottom copper gold-plated blind groove of the present application.

[0034] Description of Reference Numerals

[0035] 1-dry ink; 2-laminated resin; 21-exposed area; 22-blind groove area; 3-bottom copper; 31-expansion; 32-top groove; 4-bottom gold plating; 5-existing gold plating area; 51-bottom gold; 6-laser; 7-charged gas; 9-solder pad; 11-vacuum dust collection tube; 12-gasified resin; 13-liquefied resin; C-side elevation area; D-bottom plane area; θ-side wall bottom angle; Z-total depth of blind groove; L1-blind groove bottom protrusion distance; L2-blind groove top to pad distance; L3-blind groove bottom to pad distance. DETAILED DESCRIPTION

[0036] The exemplary embodiments of the present application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, and are not intended to exhaust all possible methods of the present application, nor to limit the scope of the present application.

[0037] like Figure 1 As shown, the embodiment of the present application provides a PCB substrate with a bottom copper gold-plated blind groove. The main body of the PCB substrate includes a laminate resin 2, a dry ink 1, a bottom copper 3, and a bottom gold-plated 4. The top surface of the laminate resin 2 itself is recessed with a blind groove area 22, and the front surface of the laminate resin 2 ( Figure 1 The upper surface of the substrate (except the blind groove area 22) is at least partially covered with dry ink 1. The bottom copper 3 is located at the bottom of the blind groove area 22. Figure 1 and Figure 3 The top surface of the bottom copper 3 is provided with a top surface groove 32, and the top surface groove 32 is filled with bottom gold plating 4, and the top surface of the bottom gold plating 4 is flush with the opening surface of the top surface groove 32 (that is, the top surface of the peripheral wall of the bottom copper 3 that defines the opening of the top groove 32). Finally, the bottom surface of the entire blind groove area 22 is covered with gold, but the side wall of the blind groove area 22 exposes the material of the laminate resin 2 itself.

[0038] In another embodiment, when observed along the depth direction of the blind groove area 22, the bottom surface area of ​​the blind groove area 22 is equal to the top surface area of ​​the bottom gold plating 4, and the top surface area of ​​the bottom copper 3 is greater than the top surface area of ​​the bottom gold plating 4. In the cross section cut along the depth direction, the bottom copper 3 has an expansion portion 31 (edge) inserted into the inside of the lamination resin 2.

[0039] The beneficial effects of adopting the above embodiment are: ensuring that the area of ​​the bottom copper 3 is large enough, firstly, the expansion portion 31 is embedded in the lamination resin 2 and assembled firmly; secondly, it can also ensure that there is enough area to occupy the bottom of the blind groove area 22, and then the bottom gold plating 4 is covered, and the relative position accuracy of the bottom copper 3 is not required to be high.

[0040] In another embodiment, the depth of the blind groove area 22 is greater than half of the thickness of the bonding resin 2. The depth of the blind groove area 22 is less than the width of the blind groove area 22. The thickness of the bottom gold plating 4 is less than half of the thickness of the bottom copper 3.

[0041] The beneficial effect of adopting the above embodiment is that the depth of the blind groove area 22 and the thickness of the bottom gold plating 4 are reasonably planned.

[0042] In another embodiment, the front surface of the pasting resin 2 around the opening of the blind groove area 22 also has an exposed area 21 not covered by the dry ink 1. The expansion size of the expansion portion 31 in the width direction of the blind groove area 22 (i.e., the size inserted into the pasting resin 2) is greater than the size of the exposed area 21 in the width direction of the blind groove area 22.

[0043] In another embodiment, if Fig.10 As shown, a pad 9 is provided between the dry ink 1 and the laminating resin 2. There is laminating resin 2 not covered by the pad 9 around the opening of the blind slot area 22, and the laminating resin 2 partially exposes the upper surface here; there is also pad 9 not covered by the dry ink 1 around the opening of the blind slot area 22, and the pad 9 partially exposes the upper surface here. That is, at the location of the blind slot area 22, the opening areas corresponding to the laminating resin 2, the pad 9, and the dry ink 1 are getting larger and larger.

[0044] like Figures 10 to 12 As shown, first, from the opening of the blind groove area 22 to the bottom surface, the width of the blind groove area 22 gradually decreases. The angle range of the junction between the side wall of the blind groove area 22 and the bottom surface of the blind groove area 22 is 90° to 110°, that is, the angle θ of the bottom angle of the side wall satisfies the range of 80° to 90°, and the angle of the junction between the side wall of the blind groove area 22 and the bottom surface of the blind groove area 22 is complementary to the angle θ of the bottom angle of the side wall. In the actual preparation method, the process capability index (Cpk) of the bottom angle θ of the side wall is equal to 1.21, and Cpk is a key indicator for measuring process stability. The higher the Cpk value, the more stable the process and the smaller the fluctuation of product quality. Here, Cpk equals 1.21, which means that the actual processing quality meets the design requirements as a whole. Secondly, the lateral dimension from the opening edge of the laminating resin 2 corresponding to the opening of the blind groove area 22 to the bottom edge of the blind groove area 22 is not greater than 2mil. The distance L2 from the top of the blind groove to the pad is not greater than 2 mil. Mil is also called milliinch, which is a unit of length, and 1 mil is equal to 25.4um. The distance L3 from the bottom of the blind groove to the pad is not greater than 50.8um. ​​Again, the lateral dimension of the opening edge of the pad 9 corresponding to the opening of the blind groove area 22 is not greater than 4 mil compared to the bottom edge of the blind groove area 22. That is, the distance L3 from the bottom of the blind groove to the pad is not greater than 4 mil, that is, the distance L3 from the bottom of the blind groove to the pad is not greater than 101.6um. The actual Cpk of the distance L3 from the bottom of the blind groove to the pad is greater than 1.33, which means that the qualified rate of the production process is very high. The lateral distance that one side of the bottom of the blind groove area 22 extends forward toward the center of the blind groove area 22 compared to the side of the opening edge of the blind groove area 22 is the blind groove bottom protruding distance L1, and the distance L3 from the bottom of the blind groove to the pad is equal to the sum of the blind groove bottom protruding distance L1 and the distance L2 from the top of the blind groove to the pad. The respective dimension values ​​of the blind groove bottom protruding distance L1, the blind groove top to the pad distance L2, and the blind groove bottom to the pad distance L3 are dimension values ​​measured along the depth direction perpendicular to the blind groove area 22. Finally, the vertical distance from the bottom surface of the blind groove area 22 to the top surface of the dry ink 1 is the total blind groove depth Z. In a non-limiting embodiment, the total blind groove depth Z is 0.429 mm.

[0045] Fig.11 and Fig.12 The electron microscope images respectively show the position indicated by the actual side wall bottom angle θ and the position indicated by the blind groove bottom protrusion distance L1.

[0046] In a non-limiting embodiment, the side wall bottom angle θ measured by actual sampling satisfies the range of 80° to 90°, with an average value of 85.93°, an average value of the blind groove bottom protrusion distance L1 of 26.72um, an average value of the blind groove top to the pad distance L2 of 18.54um, and an average value of the blind groove bottom to the pad distance L3 of 45.26um. The specific data are shown in the following table:

[0047] θ(unit:°) L1(unit: um) L2(unit: um) L3(unit: um) average value 85.93 26.72 18.54 45.26 Standard Deviation 1.12 4.57 5.80 6.71 Maximum 87.81 35.62 24.91 57.61 Minimum 83.62 19.79 7.48 35.62

[0048] like Figure 2 As shown, the manufacturing process of the PCB substrate with bottom copper gold-plated blind groove of the present application includes, for example, pattern formation, solder mask, laser grooving, cleaning treatment (i.e., preliminary cleaning), enhanced cleaning treatment (i.e., mid-section cleaning), cleaning treatment (i.e., terminal cleaning), and gold plating. Figure 2 The four modules in the process are, in the order of arrows, laser processing of blind grooves (ie, laser grooving), enhanced cleaning processing for strong contamination removal, cleaning processing, and gold plating.

[0049] After the solder mask, the blind groove process is carried out. Through enhanced cleaning treatment and two cleaning treatments, the dirt after the laser 6 slotting is removed, the influence of the dirt on the electroplating is reduced, the gold plating of the side wall of the blind groove area 22 is avoided, and the risk of high temperature and high humidity short circuit failure after packaging is reduced. In addition, the solder mask formation of the process flow is relatively easy. At this time, the blind groove process has not been carried out, and there is no deep depression on the surface of the laminated resin 2, and the overall surface is relatively flat. After the solder mask, whether it is wet oil or dry oil, there are no wrinkles, and the ink has no residual effect. The laser 6 slotting is significantly better than the boring machine in terms of length, width and depth control accuracy. The role of enhanced cleaning treatment is to strongly remove the dirt after the blind groove process. The role of the cleaning treatment is to use its water washing ability to remove the residual dirt. The cleaning treatment is carried out twice before and after to ensure that the dirt on the side wall of the blind groove area 22 is removed, thereby reducing the probability of gold plating on the side wall.

[0050] Comparison Figure 4 and Figure 5 , Figure 4 It is the cross section of the blind groove after laser grooving. Figure 5 It is the cross-sectional state of the blind groove after enhanced cleaning treatment and cleaning treatment after the blind groove process. Figure 4 The fluffy dust layer is shown in Figure 5 The fluffy dust layer is removed, and the neat tubular objects exposed are the glass fibers contained in the coating resin 2.

[0051] The finished product effect of the PCB substrate with bottom copper gold-plated blind groove of the embodiment of the present application is as follows Figure 6 As shown, Figure 6 The upper part (left side of the paper) shows the side wall without gold. Figure 6The lower part is the bottom gold-plated, that is, the bottom gold surface state. Figure 6 It can be clearly seen that the sidewalls of the blind trench region 22 do not contain gold (i.e., Figure 6 The bottom plane area D contains gold, and the side elevation area C does not contain gold). Figure 7 As shown, Figure 7 It is a slice of the blind trench area 22 after chemical nickel gold (ie Electroless Nickel Electroless Palladium Immersion Gold, abbreviated as ENEPIG). Figure 7 The right angle of the side wall of the blind groove area 22 is confirmed from the side (i.e., note that Figure 7 The verticality of the connecting lines on one side of the blind slot area 22, as well as the copper layer state at the bottom of the blind slot area 22 (i.e., Figure 7 The middle picture below connects the entire Figure 7 The light grey blocks on the left and right. Figure 7 The "gentle slope" outline in the upper left center corresponds to the object below which is the filler used for slicing, which is used to ensure that the interface state is fixed and there is no abnormal damage caused by grinding.

[0052] Figure 8 The figure shows a process problem in the field of PCB board processing. When the laser 6 processes the resin, there will be a vacuum dust collection pipe 11 to vacuum the laser 6 processing area nearby, but the subsequent palladium ions (Pd 2+ ) is also easily adsorbed on the side walls of the pits on the resin.

[0053] Step S1, laser processing: see Fig. 9 In the fourth state, a specific groove or hole is processed on the PCB board using a laser 6 to meet the electrical connection requirements; step S2, cleaning treatment (i.e., preliminary cleaning): remove the dirt generated during laser processing; step S3, enhanced cleaning treatment (i.e., mid-section cleaning): see Fig. 9 State 5, using charged gas 7 to modify the surface of the blind groove area 22 (or Cavity) after laser processing; step S4, second cleaning treatment (ie, terminal cleaning): see Fig. 9 In state six, the blind slot area 22 after being treated with the charged gas 7 is washed and cleaned to remove the residue on the PCB board to ensure that the board surface is clean and free of impurities; step S5, see Fig. 9 State seven, gold plating: gold plate the bottom copper 3.

[0054] In a non-limiting example, the laser 6 can be a high-speed laser with a small aperture, low thermal effect, and fast processing speed; in addition, the charged gas 7 can be a negatively charged gas with strong dirt removal ability, high removal efficiency, and fast speed.

[0055] Cleaning treatment, i.e. terminal cleaning, removes foreign matter from the substrate surface. During the water washing and cleaning process, the water pressure of terminal cleaning is not less than 0.6MPa. The PCB board is contacted and transported by three points. In a non-limiting embodiment, the transport mechanism can use three suction cup heads to contact the PCB board by adsorption, thereby reducing the probability of the PCB board being scratched.

[0056] Before step S1, there may be a pre-step. The pre-step includes: Pre-step S01, image formation: forming a circuit pattern on the PCB board. Pre-step S02, solder mask: see Fig. 9 In the first state, solder resist ink is applied on the PCB board to form dry ink 1 to protect the parts that do not need to be soldered.

[0057] The gold plating in step S5 can also be pre-treatment and nickel-palladium-gold plating; step S501, pre-treatment: chemically corrode the bottom copper 3 to remove the oxides, stains and uneven parts of the copper layer on the surface of the bottom copper 3, so as to ensure adhesion. Step S502, nickel-palladium-gold plating: first plate a layer of nickel on the surface of the bottom copper 3 as an intermediate layer. Then plate a layer of palladium to prevent the diffusion of nickel and ensure the stability of the plating layer. Finally, plate a layer of gold to improve the corrosion resistance and solderability of the PCB board.

[0058] After step S5, a review step may also be provided. Fig. 9 The eighth step of inspection is to use a microscope and visual inspection respectively. The actual state of the defective products during processing is shown by photos and microscope images respectively, and the typical characteristics of the defective products are made into billboards or process instructions to facilitate the inspection personnel to compare with the actual finished products one by one.

[0059] The above embodiments are only for illustrating the technical concept and features of the present application, and their purpose is to enable people familiar with this technology to understand the content of the present application and implement it. They cannot be used to limit the scope of protection of the present application. All equivalent changes or modifications made according to the spirit of the present application should be included in the scope of protection of the present application.

Claims

1. A PCB substrate with a bottom copper gold-plated blind groove, characterized in that: include: A pasting layer resin (2), the pasting layer resin (2) having a blind groove area (22) recessed from its surface, and the side wall of the blind groove area (22) exposes the material of the pasting layer resin (2); Dry ink (1), wherein the area on the front side of the laminating resin (2) except the blind groove area (22) is at least partially covered with the dry ink (1); Bottom copper (3), the bottom of the blind groove area (22) is provided with the bottom copper (3); The bottom is gold-plated (4); the upper surface of the bottom copper (3) is provided with a top surface groove (32); the top surface groove (32) is filled with the bottom gold-plated (4); and the top surface of the bottom gold-plated (4) is flush with the opening surface of the top surface groove (32).

2. The PCB substrate with bottom copper gold-plated blind groove according to claim 1, characterized in that: When observed along the depth direction of the blind groove area (22), the bottom surface area of ​​the blind groove area (22) is equal to the top surface area of ​​the bottom gold plating (4), the top surface area of ​​the bottom copper (3) is larger than the top surface area of ​​the bottom gold plating (4), and the bottom copper (3) has an expansion portion (31) inserted into the interior of the lamination resin (2).

3. The PCB substrate with bottom copper gold-plated blind groove according to claim 1, characterized in that: The depth of the blind groove area (22) is greater than half the thickness of the laminating resin (2).

4. The PCB substrate with bottom copper gold-plated blind groove according to claim 1, characterized in that: The depth value of the blind groove area (22) is smaller than the width value of the blind groove area (22).

5. The PCB substrate with bottom copper gold-plated blind groove according to claim 1, characterized in that: The thickness of the bottom gold plating (4) is less than half the thickness of the bottom copper (3).

6. The PCB substrate with bottom copper gold-plated blind groove according to claim 2, characterized in that: The front surface of the laminating resin (2) around the opening of the blind groove area (22) also has an exposed area (21) not covered by the dry ink (1).

7. The PCB substrate with bottom copper gold-plated blind groove according to claim 6, characterized in that: The expansion dimension of the expansion portion (31) in the width direction of the blind groove area (22) is greater than the dimension of the exposed area (21) in the width direction of the blind groove area (22).

8. The PCB substrate with bottom copper gold-plated blind groove according to claim 1, characterized in that: A soldering pad (9) is also provided between the dry ink (1) and the laminating resin (2); The bonding resin (2) not covered by the pad (9) exists around the opening of the blind groove area (22); and the pad (9) not covered by the dry ink (1) exists around the opening of the blind groove area (22).

9. The PCB substrate with bottom copper gold-plated blind groove according to claim 8, characterized in that: The angle between the side wall of the blind groove area (22) and the bottom surface of the blind groove area (22) is in the range of 90° to 110°; In the width direction of the blind groove area (22), the lateral dimension from the opening edge of the laminating resin (2) corresponding to the opening of the blind groove area (22) to the bottom edge of the blind groove area (22) is no greater than 2 mil; In the width direction of the blind groove area (22), the lateral dimension from the opening edge of the pad (9) corresponding to the opening of the blind groove area (22) to the bottom edge of the blind groove area (22) is no greater than 4 mil.

10. A method for preparing a PCB substrate with a bottom copper gold-plated blind groove, used for manufacturing a PCB substrate with a bottom copper gold-plated blind groove according to any one of claims 1 to 9, characterized in that: include: Step S1, laser (6) processing: processing the blind groove area (22) on the surface of the PCB board; Step S2, preliminary cleaning: cleaning the dirt generated by the laser (6) processing; Step S3, middle section cleaning: using charged gas (7) to perform surface modification on the blind groove area (22) processed by the laser (6); Step S4, terminal cleaning: washing and cleaning the blind slot area (22) after being treated by the charged gas (7); Step S5, gold plating: gold plating is performed on the bottom copper (3).

11. The method for preparing a PCB substrate having a bottom copper gold-plated blind groove according to claim 10, characterized in that: The laser (6) utilizes a laser thermal effect, and the laser thermal effect has a smaller thermal melting effect on the copper material than on the laminating resin (2); the laser (6) thermally melts the glass fibers in the laminating resin (2) and vaporizes the resin, and the laser (6) thermally melts the blind groove area (22) to a specified depth, thereby achieving molding of the blind groove area (22).

12. The method for preparing a PCB substrate with a bottom copper gold-plated blind groove according to claim 10, characterized in that: In the same unit time and the same unit area, the charged gas (7) cleans the surface of the PCB board to a greater degree than the preliminary cleaning; The charged gas (7) is a gas with negative charge.

13. The method for preparing a PCB substrate with a bottom copper gold-plated blind groove according to claim 10, characterized in that: The preliminary cleaning and the final cleaning remove the surface attachments of the PCB board; The water pressure of the terminal cleaning is not less than 0.6MPa; during the water washing cleaning, the PCB board is contacted and transported at three points.

14. The method for preparing a PCB substrate with a bottom copper gold-plated blind groove according to claim 10, characterized in that: There is also a pre-step before step S1; The preceding steps include: Pre-step S01, image formation: forming a circuit pattern on the PCB board; Pre-step S02, solder resist: applying solder resist ink on the PCB board.

15. The method for preparing a PCB substrate with a bottom copper gold-plated blind groove according to claim 10, characterized in that: The gold plating in step S5 is pre-treatment and nickel-palladium-gold plating, and an inspection step is also provided after step S5; Step S501, pre-treatment: chemically corroding the bottom copper (3) to remove oxides, stains and uneven parts on the surface of the bottom copper (3); Step 502, nickel-palladium-gold plating: first plating a layer of nickel on the surface of the bottom copper (3), then plating a layer of palladium, and finally plating a layer of gold; The inspection step includes: The PCB board is visually observed and observed using a microscope, and the defective photo of the PCB board and the defective microscope image are compared.

Images