A method for manufacturing a PCB blind hole and a PCB with blind hole

Abstract

The application provides a PCB blind insertion hole manufacturing method and a PCB with a blind insertion hole, and relates to the technical field of printed circuit board manufacturing. The PCB blind insertion hole manufacturing method comprises the following steps: processing a through hole on a first substrate and sequentially forming a first metal layer, a conductive layer and a second metal layer with first, second and third inner wall radii; laminating a second substrate after hole filling to form a composite board; performing mechanical depth-controlled drilling on the through hole, the back drilling radius being smaller than the second inner wall radius and larger than the third inner wall radius, so as to expose the second metal layer; selectively etching to remove the second metal layer, exposing the conductive layer to form a target blind insertion hole. The electroplating and surface treatment are performed under the condition of an inner layer through hole, which solves the bottleneck of high aspect ratio electroplating caused by poor flowability of blind hole chemicals; through the grading relationship of the radii, the second metal layer is used as a scratch-preventing sacrificial protective layer during back drilling, which avoids damage to the conductive layer by a drill bit, and significantly improves the conduction reliability and yield of high aspect ratio blind insertion holes.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board manufacturing technology, and in particular to a method for manufacturing blind through-holes in PCBs and a PCB having blind through-holes. Background Technology

[0002] Blind vias are a special type of conductive blind via on a printed circuit board (PCB). They are typically not plugged or soldered; instead, they are designed as metallized vias. Current conduction and signal transmission are achieved through direct mechanical contact between the component pins and the inner wall of the blind via. They are widely used in multilayer circuit boards.

[0003] However, traditional blind vias face a bottleneck in manufacturing due to limitations in their thickness-to-diameter ratio (the ratio of hole depth to hole diameter). Because one end of a blind via is closed, the flow and circulation of chemicals deep within it are poor. When the thickness-to-diameter ratio is greater than 1:1, electroplating is prone to defects such as incomplete plating and hole breakage. Furthermore, subsequent surface treatments (such as gold plating) are difficult to uniformly cover the depths of the blind via, which can easily lead to abnormal contact resistance and reduced product reliability.

[0004] The existing typical method involves laminating multilayer boards, directly creating blind holes on the board surface using mechanical controlled-depth drilling, and then performing electroplating and surface treatment. Due to the bottleneck in the flow of the aforementioned chemicals, the aspect ratio production capability of this existing method is usually limited to below 1:1.

[0005] Therefore, how to manufacture blind vias with high aspect ratios while ensuring the quality of hole wall metallization and the uniformity of surface treatment is a core technical problem that urgently needs to be solved in the industry. Summary of the Invention

[0006] To overcome the problems existing in related technologies, the purpose of this invention is to provide a method for manufacturing blind through-holes on a PCB and a PCB with blind through-holes. The method for manufacturing blind through-holes on a PCB is to complete the core metallization and surface treatment processes of the blind through-holes in advance in the through-hole state of the inner core board. After plugging and pressing, the conductive layer is exposed again by using controlled depth drilling and selective etching. This overcomes the problems of poor flowability of the blind through-hole solution, which easily leads to metallization defects on the hole wall and uneven surface treatment under high aspect ratios.

[0007] A method for manufacturing a blind through-hole on a PCB includes: Through holes are fabricated on the first substrate; A first metal layer is formed on the surface of the first substrate, and the first metal layer has a first inner wall radius at the through hole; A conductive layer is formed on the surface of the first metal layer, and the conductive layer has a second inner wall radius at the through hole; A second metal layer is formed on the surface of the conductive layer, and the second metal layer has a third inner wall radius at the through hole; Fill the through holes and stack the first substrate with at least one second substrate to form a multilayer composite board; Mechanical depth-controlled drilling is performed on the outer surface of the multilayer composite board, corresponding to the through hole, to expose the second metal layer at the through hole; wherein, the mechanical depth-controlled drilling has a preset processing radius, which is smaller than the radius of the second inner wall and larger than the radius of the third inner wall; Selective etching removes the second metal layer, exposing the conductive layer to form the target blind via.

[0008] Furthermore, the conductive layer is a gold-plated layer; The second metal layer is an electroplated copper layer.

[0009] Furthermore, the selective etching is performed using an alkaline etching solution.

[0010] Furthermore, the thickness of the first metal layer is 20 micrometers to 35 micrometers; The thickness of the second metal layer is 150 micrometers to 200 micrometers.

[0011] Furthermore, prior to the step of forming a conductive layer on the surface of the first metal layer, the method further includes: A first dry film is attached to the surface of the first substrate on which the first metal layer is formed. After exposure and development, the first dry film has a first opening at the through hole. The radius of the first opening is smaller than the radius of the first inner wall, and the difference between the radius of the first inner wall and the radius of the first opening is less than or equal to 3 mil. Before the step of forming a second metal layer on the surface of the conductive layer, the method further includes: After removing the first dry film, a second dry film is attached to the surface of the first substrate on which the conductive layer is formed. After exposure and development, the second dry film has a second opening at the through hole; wherein the radius of the second opening is smaller than the radius of the second inner wall, and the difference between the radius of the second inner wall and the radius of the second opening is less than 3 mil.

[0012] Furthermore, after the step of forming a second metal layer on the surface of the conductive layer and before the step of filling the via, the method further includes: Remove the second dry film; Electroplating of the entire plate with copper forms an auxiliary electroplated copper layer with a thickness of 8 to 12 micrometers.

[0013] Furthermore, the radius of the through hole is 0.05 mm larger than the radius of the target blind insertion hole; The preset processing radius is 0.05 mm smaller than the radius of the target blind insertion hole.

[0014] Furthermore, the step of filling the through hole specifically includes: The through-holes were filled with plugging resin; The pore-filling resin filling the through-hole is cured. The surface of the first substrate is ground to smooth out the pore-filling resin that has been cured and protruded outside the through hole opening.

[0015] Furthermore, after the step of selectively etching away the second metal layer, the method further includes: Solder resist printing and surface treatment are performed on the outer surface of the multilayer composite board.

[0016] The second objective of this invention is to provide a PCB with blind sockets, which is manufactured using the above-described method for manufacturing blind sockets on PCBs.

[0017] The beneficial effects of this invention are as follows: This invention provides a method for manufacturing PCB blind vias. This method involves pre-completing the core metallization and surface treatment processes of the blind via in the inner core board through-hole state. After plugging and pressing, controlled-depth drilling combined with selective etching re-exposes the conductive layer. The core electroplating steps are all performed in the inner layer through-hole state, resulting in significantly better exchange capacity than in the blind via state. This allows for uniform coverage of the first metal layer and conductive layer deep within the hole wall, overcoming the problem of poor plating quality in high aspect ratio blind vias due to poor chemical exchange. Controlled-depth drilling typically has unavoidable Z-axis and XY-axis alignment tolerances, and direct back-drilling easily damages the conductive layer. This invention utilizes the relationship between the first, second, and third inner wall radii and the preset processing radius, using the second metal layer as a sacrificial protective layer against mechanical scratches. This not only drills through and removes the central resin but also ensures that the underlying micron-level conductive layer is protected from mechanical cutting scratches and other adverse effects caused by processing vibrations. The second metal layer exposed by the drill bit is selectively etched away in subsequent steps. The conductive layer not only remains intact as a surface protective layer for the finished blind socket, but also acts as an anti-corrosion stop layer, protecting the lower first metal layer from being etched, thus improving the conductivity reliability and yield of the blind socket. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the method for manufacturing PCB blind through-holes provided in this application; Figure 2 This is a schematic diagram of the process steps and structural changes during the inner layer fabrication stage in an embodiment of the present invention; Figure 3 This is a schematic diagram of the process steps and structural changes during the outer layer fabrication stage in an embodiment of the present invention; Figure 4 This is a partial enlarged schematic diagram showing the relationship between the drill bit and the spatial gradation and borehole diameter of each layer during mechanical depth-controlled drilling in an embodiment of the present invention. Detailed Implementation

[0020] Preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0021] Example 1

[0022] like Figures 1 to 4 As shown, this embodiment discloses a method for manufacturing a blind through-hole on a PCB. In this embodiment, the finished radius R of the target blind through-hole to be manufactured is set to 0.15 mm (i.e., the finished hole diameter D is 0.3 mm). Figures 1 to 3 As shown, the manufacturing method of this blind socket specifically includes the following steps: Step 1: Process through holes on the first substrate. A double-sided copper-clad laminate with a thickness of 0.2 mm was selected as the first substrate (i.e., the inner core board). Through holes were drilled on the first substrate using CNC mechanical drilling technology. The processing radius of the through holes was set to 0.20 mm (i.e., the drill diameter D1 is 0.4 mm, which is 0.05 mm larger than the finished radius R of the target blind through hole).

[0023] Step 2: Form a first metal layer on the surface of the first substrate. The first substrate after the hole is opened is deburred and desmeared, and then chemical copper plating is performed [4]. After the copper plating is completed, the primary hole copper on the inner wall of the through hole is thickened by electroplating. In this embodiment, the single-sided thickness of the primary hole copper is controlled to be 25 μm by electroplating, and the primary hole copper constitutes the first metal layer.

[0024] At this point, the first metal layer forms a first inner wall radius r1 at the through hole, which is 0.20 mm - 0.025 mm = 0.175 mm. Step 3: Form a conductive layer on the surface of the first metal layer. A first dry film is attached to the surface of a first substrate on which a first metal layer is formed, and then exposed and developed using film. After development, the first dry film has a first opening at the through-hole. The radius of the first opening is controlled to be smaller than the radius r1 of the first inner wall, and the difference between the radius r1 of the first inner wall and the radius of the first opening is controlled to be approximately 2 mil (approximately 0.05 mm, meeting the requirement of less than or equal to 3 mil), so that the edge of the first dry film appropriately enters the opening of the through-hole.

[0025] Subsequently, the first substrate is placed into an electroplating bath, and a gold plating layer with a thickness of 2 μm is electroplated on the exposed surface of the first metal layer. This gold plating layer constitutes the conductive layer.

[0026] After electroplating, the conductive layer forms a second inner wall radius r2=r1-2μm=0.175mm-0.002mm=0.173mm at the through hole, and then the first dry film is removed.

[0027] Step 4: Form a second metal layer on the surface of the conductive layer. A second dry film is attached to the surface of a first substrate on which a conductive layer is formed, and then exposed and developed. After development, the second dry film has a second opening at the through-hole. The radius of the second opening is controlled to be smaller than the radius r2 of the second inner wall, and the difference between the radius r2 of the second inner wall and the radius of the second opening is controlled to be approximately 2 mil (approximately 0.05 mm, meeting the requirement of less than 3 mil), so that the edge of the second dry film appropriately enters the opening of the through-hole.

[0028] Subsequently, an in-hole copper plating process is performed, in which thickened copper is electroplated on the surface of the conductive layer (gold plating layer), and the single-sided thickness of the electroplated copper layer is controlled to be 150μm. This electroplated copper layer constitutes the second metal layer.

[0029] After electroplating, the second metal layer forms a third inner wall radius r3=r2-150μm=0.173mm-0.150mm=0.023 mm at the through hole, and then the second dry film is removed.

[0030] Step 5: Fill the through holes and stack the sheets. After the dry film is removed, the first substrate is subjected to full-board copper electroplating, forming a 10μm thick layer on the board surface and the surface of the vias. An auxiliary electroplated copper layer (controlled between 8 and 12 μm) is applied.

[0031] Next, an epoxy resin type plugging resin is used to fill the remaining space in the through holes through a vacuum plugging machine. The first substrate is sent into an oven for curing treatment. After curing is completed, a belt grinder is used to grind the surface of the first substrate, so as to sand the plugging resin that protrudes outside the through hole orifice after curing flat, and make the end face of the plugging resin flush with the copper layer on the board surface.

[0032] After grinding is completed, the first substrate, the prepreg (PP) and the outer copper foil serving as the second substrate are laminated according to the lamination layout requirements, and sent into a laminator for high-temperature and high-pressure lamination to form a multilayer composite board.

[0033] Step 6: Mechanical depth-controlled drilling Place the laminated multilayer composite board on the back drill machine table

[10] . On the outer surface of the multilayer composite board, mechanical depth-controlled drilling is performed at the position corresponding to the axial line of the through hole. In this embodiment, the preset machining radius R of the back drill bit is set drill to 0.10 mm (that is, the back drill hole diameter D2 is 0.20 mm, which is 0.05 mm smaller than the finished product radius R of the target blind jack).

[0034] Since in this embodiment, r3=0.023 mm, r2=0.173 mm, the set preset machining radius R drill =0.10 mm, which satisfies the gradation relationship of r3<R drill <r2.

[0035] During the drilling process, the drill bit can drill and remove the plugging resin distributed inside the third inner wall radius r3, and cut into the second metal layer with a thickness of 150 μm. Since the preset machining radius R drill is smaller than the second inner wall radius r2, and a physical safety distance of 0.073 mm (73 μm) is reserved between the two, the upright side edge of the drill bit will not contact or scratch the peripheral conductive layer (gold-plated layer) during the mechanical cutting process.

[0036] Control the depth parameter of mechanical drilling, so that the drill bit removes the resin in the through hole and stops inside the additional copper-plated layer, exposing the additional copper-plated layer, and then retracts the drill bit.

[0037] Step 7: Selective etching to expose the blind jack After the depth-controlled drilling is completed, a dry film is attached to the outer surface of the multilayer composite board and windowed. An alkaline etching solution is selected to perform spray etching treatment on the multilayer composite board. The alkaline etching solution enters the hole along the back drill cavity. Since the conductive layer (gold-plated layer) has chemical stability in the alkaline etching solution, the etching solution can selectively rapidly dissolve and peel off the exposed second metal layer (electroplated copper layer). When the etching solution dissolves to the surface of the conductive layer (gold-plated layer), the etching reaction stops.

[0038] After etching, the dry film is removed, completely releasing the space occupied by the second metal layer and exposing the surface of the complete conductive layer (gold plating). Finally, solder resist is printed on the outer layer of the multilayer composite board, followed by conventional surface treatment, to create a target blind via with a high aspect ratio and gold plating covering the sidewalls.

[0039] Example 2

[0040] like Figures 1 to 4 As shown, this embodiment discloses a method for manufacturing a PCB blind through-hole. In this embodiment, the target blind through-hole to be manufactured is assumed to connect the second layer (L2 layer) to the fifth layer (L5 layer) in a multilayer composite board, and its finished radius R is 0.20mm (i.e., the finished hole diameter D is 0.40mm).

[0041] A four-layer board consisting of the second to fifth laminated layers is selected as the first substrate, and the thickness of the first substrate is 0.6 mm. Through holes penetrating from the second to the fifth layers are machined on the first substrate using CNC mechanical drilling. The machining radius of the through holes is set to 0.25 mm (i.e., the diameter of the through hole is 0.50 mm, which is 0.05 mm larger than the finished radius R of the target blind insertion hole).

[0042] After descaling and removing adhesive residue from the first substrate, chemical copper plating and a first-stage copper electroplating are performed to form a primary copper layer on the inner wall of the via, which serves as the first metal layer. The thickness of this primary copper layer on one side is controlled to be 30 micrometers. At this point, the first metal layer forms a first inner wall radius r1 of 0.22 mm (i.e., 220 micrometers) at the via.

[0043] A first dry film is attached to the surface of a first substrate. After exposure and development, a gold plating layer is electroplated on the surface of a first metal layer to form a conductive layer, with the thickness of the gold plating layer controlled to be 1.5 micrometers on one side. The opening radius of the first dry film at the via after development is smaller than the radius of the first inner wall, and the difference between the radius of the first inner wall and the radius of the first opening is controlled to be approximately 1.5 mil (approximately 38 micrometers, meeting the requirement of less than or equal to 3 mil), so that the first dry film forms a slight obstruction at the edge of the via. After electroplating the gold plating layer, the conductive layer forms a second inner wall radius r2 of 0.2185 mm (i.e., 218.5 micrometers) at the via.

[0044] After removing the first dry film, a second dry film is reattached to the surface of the first substrate. After exposure and development, copper electroplating is performed on the gold-plated layer surface within the holes. The electroplating thickness of the copper layer is controlled to be 180 micrometers on one side, forming the second metal layer. The opening radius of the developed second dry film at the via is smaller than the second inner wall radius, and the difference between the second inner wall radius and the second opening radius is controlled to be approximately 1.5 mil. After copper plating, the second metal layer forms a third inner wall radius r3 of 0.0385 mm (i.e., 38.5 micrometers) at the via. The second dry film is then removed.

[0045] A copper auxiliary electroplating layer with a thickness of 12 micrometers (controlled between 8 and 12 micrometers) is formed on the entire surface of the first substrate by electroplating. The remaining space inside the through-holes is filled with via-filling resin, and after high-temperature curing, the via-filling resin protruding from the through-hole openings on the surface of the first substrate is ground smooth. Next, a first layer (L1 layer) of outer copper foil and a prepreg are stacked on top of the first substrate, and a sixth layer (L6 layer) of outer copper foil and a prepreg are stacked on the bottom of the first substrate (the aforementioned outer copper foil serves as the second substrate). The substrate is then fed into a laminator for multi-layer lamination to obtain a six-layer composite board. At this point, the original through-holes are sealed inside the six-layer composite board by the outer dielectric layer and copper foil.

[0046] On the outer surface of the first layer (L1 layer) of the six-layer composite board, corresponding to the axis of the through hole, a back drill is used for drilling. The preset machining radius R of the back drill bit... drill The radius is set to 0.15mm (i.e., the back drill diameter D2 is 0.30mm, which is 0.05mm smaller than the finished radius R of the target blind insertion hole). In this embodiment, r3 is 0.0385mm, r2 is 0.2185mm, and the preset machining radius R is set to... drill =0.15mm satisfies r3 < R drill The gradation relationship is < r2. A mechanical drill bit penetrates the first copper foil layer, the prepreg, and reaches deep into the original through-hole, removing most of the plugging resin and cutting into the second metal layer. Due to a 0.0685mm (68.5 micrometers) safety clearance between the preset machining radius and the second inner wall radius, the drill bit's side edge does not contact or scratch the conductive layer (gold plating) during drilling. The depth of back drilling is controlled so that the drill bit stops longitudinally inside the copper plating layer, exposing its cross-section.

[0047] Localized openings are created on the outer surface of a six-layer composite board by dry film exposure and development, followed by spray etching using an alkaline etching solution. The alkaline etching solution chemically removes the second metal layer (copper plating) exposed by mechanical drilling, stopping when it reaches the conductive layer (gold plating). Finally, the film is stripped to expose the complete conductive layer (gold plating) surface within the hole. Then, solder mask is applied to the outer layer, followed by surface treatment to obtain the target blind via.

[0048] Example 3

[0049] like Figures 1 to 4 As shown, this embodiment discloses a PCB (printed circuit board) with blind through-holes manufactured using the method described in Embodiment 1 or Embodiment 2. A vertical section of the multilayer composite board at the target blind through-hole location was performed, and its microstructure was observed. The cross-sectional microstructure of the target blind through-hole exhibited clear physical boundaries and material delamination characteristics.

[0050] The target blind insertion hole includes a mechanically controlled depth drilling section and a non-drilled section connected to its bottom end. Inside the dielectric layer of the multilayer composite board, the sidewall of the mechanically controlled depth drilling section consists of, from the outside to the inside, the substrate of the first substrate, the first metal layer, and the conductive layer, and the innermost radial surface of the conductive layer is directly exposed to form the conductive insertion surface of the blind insertion hole.

[0051] The mechanically controlled depth drilling section has a preset processing radius R. drill Because during the processing, the preset processing radius R drill The radius of the second inner wall r2 of the conductive layer at the through hole is smaller than that of the conductive layer. In a microsection, the exposed surface of the conductive layer presents a continuous electroplated structure without mechanical cutting scratches.

[0052] At the junction of the mechanically controlled depth drilling section and the non-drilling section (i.e., the bottom of the controlled depth drilling), the original inner wall radius r2 and the preset processing radius R are located at... drill The second metal layer between the holes is removed by the selective etching, thereby forming an annular step extending radially toward the center of the hole at the junction. The surface of the annular step is covered by the conductive layer, and the radial width of the annular step corresponds to the second inner wall radius r2 and the preset machining radius R. drill The difference.

[0053] In the non-drilled section, the internal channel of the through hole still retains a complete second metal layer and the innermost plugging resin. The bottom end of the plugging resin in the non-drilled section abuts against the outer dielectric layer at the bottom of the multilayer composite board. The second metal layer retained in the non-drilled section is tightly bonded to the conductive layer and, together with the first metal layer, forms the bottom base of the blind insertion hole.

[0054] Through this structure, the upright sidewalls of the target blind socket provide a conductive surface for pin insertion contact, and form mechanical support through the second metal layer remaining in the non-drilled section and the plugging resin to withstand the mechanical stress generated during pin insertion and removal.

[0055] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this application. Any specific values ​​in all examples shown and discussed herein should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0056] Furthermore, it should be noted that the use of terms such as "first" and "second" is merely for ease of distinction, and unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for manufacturing a blind through-hole on a PCB, characterized in that, Includes the following steps: Through holes are fabricated on the first substrate; A first metal layer is formed on the surface of the first substrate, and the first metal layer has a first inner wall radius at the through hole; A conductive layer is formed on the surface of the first metal layer, and the conductive layer has a second inner wall radius at the through hole; A second metal layer is formed on the surface of the conductive layer, and the second metal layer has a third inner wall radius at the through hole; Fill the through holes and stack the first substrate with at least one second substrate to form a multilayer composite board; Mechanical depth-controlled drilling is performed on the outer surface of the multilayer composite board, corresponding to the through hole, to expose the second metal layer at the through hole; wherein, the mechanical depth-controlled drilling has a preset processing radius, which is smaller than the radius of the second inner wall and larger than the radius of the third inner wall; Selective etching removes the second metal layer, exposing the conductive layer to form the target blind via.

2. The method for manufacturing a PCB blind through-hole according to claim 1, characterized in that: The conductive layer is a gold-plated layer; The second metal layer is an electroplated copper layer.

3. The method for manufacturing a PCB blind through-hole according to claim 2, characterized in that: The selective etching is performed using an alkaline etching solution.

4. The method for manufacturing a PCB blind through-hole according to any one of claims 1 to 3, characterized in that: The thickness of the first metal layer is 20 micrometers to 35 micrometers; The thickness of the second metal layer is 150 micrometers to 200 micrometers.

5. The method for manufacturing a PCB blind socket according to claim 1, characterized in that: Before the step of forming a conductive layer on the surface of the first metal layer, the method further includes: A first dry film is attached to the surface of the first substrate on which the first metal layer is formed. After exposure and development, the first dry film has a first opening at the through hole. The radius of the first opening is smaller than the radius of the first inner wall, and the difference between the radius of the first inner wall and the radius of the first opening is less than or equal to 3 mil. Before the step of forming a second metal layer on the surface of the conductive layer, the method further includes: After removing the first dry film, a second dry film is attached to the surface of the first substrate on which the conductive layer is formed. After exposure and development, the second dry film has a second opening at the through hole; wherein the radius of the second opening is smaller than the radius of the second inner wall, and the difference between the radius of the second inner wall and the radius of the second opening is less than 3 mil.

6. The method for manufacturing a PCB blind socket according to claim 5, characterized in that: After the step of forming a second metal layer on the surface of the conductive layer and before the step of filling the via, the method further includes: Remove the second dry film; Electroplating of the entire plate with copper forms an auxiliary electroplated copper layer with a thickness of 8 to 12 micrometers.

7. The method for manufacturing a PCB blind socket according to claim 1, characterized in that: The radius of the through hole is 0.05 mm larger than the radius of the target blind insertion hole; The preset processing radius is 0.05 mm smaller than the radius of the target blind insertion hole.

8. The method for manufacturing a PCB blind through-hole according to claim 1, characterized in that: The step of filling the through hole specifically includes: The through-holes were filled with plugging resin; The pore-filling resin filling the through-hole is cured. The surface of the first substrate is ground to smooth out the pore-filling resin that has been cured and protruded outside the through hole opening.

9. The method for manufacturing a PCB blind through-hole according to claim 1, characterized in that: After the step of selectively etching away the second metal layer, the method further includes: Solder resist printing and surface treatment are performed on the outer surface of the multilayer composite board.

10. A PCB with blind sockets, characterized in that, It is manufactured using the PCB blind socket manufacturing method according to any one of claims 1 to 9.

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