Manufacturing method of PCB (Printed Circuit Board) with lines embedded on two sides

Abstract

The invention relates to the technical field of printed circuit boards, in particular to a method for manufacturing a PCB (printed circuit board) with circuits embedded on two sides, which comprises the following steps of: manufacturing the circuits on a thicker single-sided PCB, pressing the circuits into an insulating adhesive film to obtain single-sided embedded circuit boards, and adhering two single-sided embedded circuit boards to a high-temperature-resistant adhesive film to obtain a double-sided embedded circuit board. And a circle of copper-plated conductive through holes are formed in the edge of each unit of the double-sided embedded circuit board, so that the overall strength of the double-sided embedded circuit board is improved, and meanwhile, copper-plated conductive blind holes are formed, so that circuits on the upper and lower board surfaces form a loop. The thickness of the single-face buried circuit board is large, the strength is high, and the situation that the PCB warps when a single-layer circuit is manufactured can be avoided. According to the method, the pressing time is short, the pressing temperature is low, and the problem of PCB warping caused by asymmetry of circuit patterns of two single-face buried circuit boards can be avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of printed circuit boards (PCB boards), and in particular relates to a method for manufacturing a PCB board with double-sided embedded circuits. Background Art

[0002] At present, consumer terminals represented by mobile phones and smart wearable products have an increasing demand for thinner and higher-density devices. Product design often reduces the number of layers of PCB boards and increases the wiring density of PCB boards to achieve thinner and higher-density devices.

[0003] The process of embedding circuits does not need to consider the etching compensation of circuits, which can effectively reduce the difficulty of making fine circuits and improve the wiring density of PCBs. PCB boards with embedded circuits can usually only process single-sided circuit boards. When making PCB boards with embedded circuits on both sides, if the materials or circuit patterns of the upper and lower single-sided circuit boards are quite different, the two single-sided circuit boards are pressed onto a dielectric layer through high-temperature vacuum. Due to the asymmetric structure of the board or stress, this double-sided board often has serious warping or even curling. Summary of the invention

[0004] The object of the present invention is to provide a method for manufacturing a PCB board with double-sided embedded circuits to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for manufacturing a PCB board with double-sided embedded circuits, comprising the following steps: Step 1: Provide a PCB single-sided board, the single-sided board includes an insulating dielectric layer and a temporary adhesive layer, the temporary adhesive layer includes two opposite upper surfaces and a lower surface, the lower surface of the temporary adhesive layer is bonded to the upper surface of the insulating dielectric layer, and the upper surface of the temporary adhesive layer is bonded to the copper foil layer.

[0006] Step 2: Performing pattern transfer on the surface of the copper foil layer of the PCB to form a dry film pattern layer on the surface of the copper foil layer.

[0007] Step 3: Electroplating is performed on the portion of the copper foil layer not covered by the dry film pattern layer to form a circuit.

[0008] Step 4: using a chemical solution to remove the dry film pattern layer.

[0009] Step 5: Press an insulating adhesive film on the surface of the circuit, and level the surface of the insulating adhesive film to obtain a single-sided buried circuit board.

[0010] Step 6: Press the two single-sided embedded circuit boards onto the upper and lower surfaces of a high-temperature resistant adhesive layer respectively, and bond the insulating adhesive film layers of the two single-sided embedded circuit boards to the upper and lower surfaces of the high-temperature resistant adhesive layer.

[0011] Step 7: Bake the board, the temporary adhesive layer loses its stickiness and is separated from the surface of the copper foil layer, thereby obtaining a double-sided board with embedded circuits on both sides.

[0012] Step 8: Processing blind holes that do not penetrate the double-sided board on the double-sided board with embedded circuits on both sides, and processing a circle of through holes that penetrate the double-sided board on the edge of each unit of the double-sided board.

[0013] Step nine: Cover the upper and lower surfaces of the double-sided board processed with blind holes and through holes with dry film, perform pattern transfer, and form a portion not covered by the dry film at the opening position of the blind hole, and form a portion not covered by the dry film at the opening position of the blind hole.

[0014] Step ten: performing electroplating to form copper-plated conductive holes at the positions of the blind holes and copper-plated conductive through holes at the positions of the through holes.

[0015] Step 11: using a chemical solution to remove the dry film pattern layer.

[0016] Step 12: Use an etching solution to remove the copper foil layer to expose the circuit.

[0017] Preferably, the width of the line is ≥7µm.

[0018] Preferably, the thickness of the insulating dielectric layer (110) is ≥300µm.

[0019] Preferably, the thickness of the copper foil layer is H1, and 3µm≤H1≤12µm.

[0020] Preferably, the thickness of the insulating film layer and the high temperature resistant adhesive layer are both H2, and 10µm≤H2≤100µm.

[0021] Preferably, the thickness of the line is H3, and 5µm≤H3≤30µm.

[0022] Preferably, the diameters of the blind hole and the through hole are both D1, and 50µm≤D1≤150µm.

[0023] Preferably, the temporary adhesive layer in step one is a pyrolytic adhesive.

[0024] Preferably, in step five, a vacuum laminating machine is used to pre-laminate and level the insulating adhesive film, and the pre-laminating and leveling temperature is 70-100° C., and the pre-laminating and leveling time is 30-120 seconds.

[0025] Preferably, in step six, the single-sided embedded circuit board is pressed onto the high-temperature resistant adhesive layer using a common laminating machine, and the laminating temperature is 20-100° C. and the laminating time is 30-120 seconds.

[0026] Preferably, in step seven, the temporary adhesive layer loses its stickiness by baking the plate, and the baking temperature is 120-150° C. and the baking time is 30-120 seconds.

[0027] Preferably, in step eight, the blind hole and the through hole are processed by laser ablation process.

[0028] Preferably, in step four and step eleven, an alkaline chemical solution is used to remove the dry film pattern layer and the dry film pattern layer.

[0029] Preferably, the through holes made at the edge of the unit in step eight and step ten form a rectangle, and the side lengths L1 and L2 of the rectangle are both ≤15 mm.

[0030] Compared with the prior art, the present invention has the following beneficial effects: The present invention first makes a circuit on a thicker PCB single-sided board, and then presses the circuit into an insulating film to obtain a single-sided buried circuit board, and then sticks two single-sided buried circuit boards on a high-temperature resistant film to obtain a double-sided buried circuit board, and makes a circle of copper-plated conductive through holes on the edge of each unit of the double-sided buried circuit board, thereby improving the overall strength of the double-sided buried circuit board, and at the same time makes copper-plated conductive blind holes so that the circuits on the upper and lower board surfaces form a loop. The single-sided buried circuit board has a large thickness and high strength, which can avoid the situation where the PCB warps when a single-layer circuit is made. In addition, the two single-sided buried circuit boards are stuck to a high-temperature resistant film by a normal temperature pressing method, and the pressing time is as short as a few minutes, while the prior art needs to use a high temperature of more than 150 degrees and hot pressing under vacuum for at least 45 minutes. The present invention has a short pressing time and a low pressing temperature, which can avoid the problem of PCB warping caused by the asymmetry of the circuit patterns of the two single-sided buried circuit boards.

[0031] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings herein are incorporated into and constitute a part of the specification to illustrate embodiments consistent with the present application and are used together with the specification to explain the principles of the present application. At the same time, these drawings and text descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application for those skilled in the art by referring to specific embodiments.

[0033] Figure 1 It is a schematic diagram of the processing process of a single-sided PCB of the present invention; Figure 2It is a schematic diagram of the processing process of the single-sided buried circuit board of the present invention; Figure 3 It is a schematic diagram of the processing process of the double-sided buried circuit board of the present invention; Figure 4 It is a schematic diagram of the manufacturing process of through holes, blind holes and circuits of the double-sided buried circuit board of the present invention; Figure 5 A top view of the through-hole distribution of the double-sided buried circuit board of the present invention; Figure 6 It is a side view of the through-hole distribution of the double-sided buried circuit board of the present invention along the AA′ longitudinal section.

[0034] In the figure: 1, PCB single-sided board; 2, single-sided buried circuit board; 3, double-sided buried circuit board; 110, insulating dielectric layer; 111, temporary adhesive layer; 112, copper foil layer; 113, first dry film pattern layer; 114, insulating film layer; 115, high temperature resistant adhesive layer; 116, second dry film pattern layer; 1a, part not covered by dry film pattern layer; 1b, circuit; 2a, blind hole that does not penetrate the double-sided board; 2b, area where the blind hole opening is not covered by dry film; 2c, copper-plated conductive blind hole; 3a, through hole that does not penetrate the double-sided board; 3b, area where the blind hole opening is not covered by dry film; 3c, copper-plated conductive through hole. DETAILED DESCRIPTION

[0035] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0036] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0038] In one embodiment, see Figures 1 to 6 A method for manufacturing a double-sided embedded circuit PCB board includes the following steps: Step 1: Provide a PCB single-sided board 1, wherein the single-sided board 1 includes an insulating dielectric layer 110 and a temporary adhesive layer 111, wherein the temporary adhesive layer 111 includes two opposite upper surfaces and a lower surface, wherein the lower surface of the temporary adhesive layer 111 is bonded to the upper surface of the insulating dielectric layer 110, and the upper surface of the temporary adhesive layer 111 is bonded to the copper foil layer 112.

[0039] Step 2: Performing pattern transfer on the surface of the copper foil layer 112 of the PCB to form a first dry film pattern layer 113 on the surface of the copper foil layer 112 .

[0040] Step 3: electroplating is performed on the portion 1a of the copper foil layer 112 not covered by the first dry film pattern layer 113 to form a circuit 1b.

[0041] Step 4: using a chemical solution to remove the first dry film pattern layer 113 .

[0042] Step 5: Press an insulating adhesive film 114 on the surface of the circuit 1 b , and flatten the surface of the insulating adhesive film 114 to obtain a single-sided buried circuit board 2 .

[0043] Step 6: Press the two single-sided embedded circuit boards 2 onto the upper and lower surfaces of a high-temperature resistant adhesive layer 115 respectively, and bond the insulating adhesive film layers 114 of the two single-sided embedded circuit boards 2 to the upper and lower surfaces of the high-temperature resistant adhesive layer 115 .

[0044] Step 7: Bake the board, the temporary adhesive layer 111 loses its stickiness and is separated from the surface of the copper foil layer 112, thereby obtaining a double-sided board 3 with embedded circuits on both sides.

[0045] Step eight: processing blind holes 2a that do not penetrate the double-sided board 3 with embedded circuits on both sides, and processing a circle of through holes 3a that penetrate the double-sided board at the edge of each unit of the double-sided board.

[0046] Step nine: Cover the upper and lower surfaces of the double-sided board 3 processed with the blind hole 2a and the through hole 3a with a dry film 116, perform pattern transfer, and form a portion 2b not covered by the dry film at the opening position of the blind hole 2a, and form a portion 3b not covered by the dry film at the opening position of the blind hole 3a.

[0047] Step ten: perform electroplating to form a copper-plated conductive hole 2c at the position of the blind hole 2a, and form a copper-plated conductive through hole 3c at the position of the through hole 3a.

[0048] Step 11: Use a chemical solution to remove the second dry film pattern layer 116 .

[0049] Step 12: Use an etching solution to remove the copper foil layer 112 to expose the circuit 1b.

[0050] During the operation, a PCB single-sided board 1 is prepared, and the PCB single-sided board 1 is composed of an insulating dielectric layer 110 and a temporary adhesive layer 111. The temporary adhesive layer 111 uses a thermosetting adhesive, which is sticky at room temperature and can firmly adhere the copper foil layer 112 and the insulating dielectric layer 110, but loses its stickiness after high-temperature baking, which is convenient for subsequent separation. The two opposite surfaces of the temporary adhesive layer 111 are the upper surface and the lower surface, wherein the lower surface is bonded to the upper surface of the insulating dielectric layer 110, and the upper surface is bonded to the copper foil layer 112.

[0051] Next, pattern transfer is performed on the surface of the copper foil layer 112. First, a photosensitive dry film (i.e., the first dry film pattern layer 113) is coated on the copper foil layer 112 using photolithography technology, and then the dry film is exposed and developed to form a desired circuit pattern on the copper foil layer 112. In this step, the portion covered by the dry film pattern layer 113 is the portion of the copper foil that needs to be retained, and the uncovered portion is removed in a subsequent step.

[0052] Then, electroplating is performed on the portion 1a of the copper foil layer 112 not covered by the first dry film pattern layer 113. The electroplating solution is usually a copper sulfate solution, and a copper plating layer, i.e., the circuit 1b, is formed on the portion of the copper foil not covered by the dry film by electroplating. During the electroplating process, parameters such as the concentration, temperature, and current density of the electroplating solution need to be controlled to ensure the thickness and uniformity of the circuit 1b.

[0053] After the electroplating is completed, the first dry film pattern layer 113 is removed using a chemical solution to expose the unplated portions of the copper foil layer 112 , which will be etched away in subsequent steps.

[0054] An insulating film 114 is pressed on the surface of the circuit 1b. The insulating film 114 is made of epoxy cyanate resin, modified polyimide (PI) or modified polyethylene terephthalate (PET) and has good insulation and temperature resistance. During the pressing process, the pressure and temperature need to be controlled so that the insulating film 114 is tightly bonded to the circuit 1b, and the surface of the insulating film 114 is flattened to obtain a single-sided buried circuit board 2.

[0055] The two single-sided embedded circuit boards 2 are respectively pressed onto the upper and lower surfaces of a high-temperature resistant adhesive layer 115. The high-temperature resistant adhesive layer 115 is made of a high-temperature resistant material such as modified polyimide or modified polytetrafluoroethylene, which can maintain viscosity at high temperatures to ensure that the two single-sided embedded circuit boards 2 are firmly bonded. During the pressing process, the pressure and temperature need to be controlled so that the insulating adhesive film layers 114 of the two single-sided embedded circuit boards 2 are tightly bonded to the upper and lower surfaces of the high-temperature resistant adhesive layer 115.

[0056] The assembled board is baked, and the baking temperature and time are determined according to the properties of the temporary adhesive layer 111. During the baking process, the temporary adhesive layer 111 loses its stickiness and separates from the surface of the copper foil layer 112, thereby obtaining a double-sided board 3 with embedded circuits on both sides. At this time, the upper and lower sides of the double-sided board 3 are respectively composed of the circuits 1b of the two single-sided embedded circuit boards 2 and the insulating adhesive film 114.

[0057] Blind holes 2a that do not penetrate the double-sided board 3 with embedded circuits on both sides are processed. The positions and number of blind holes 2a are determined according to the circuit design requirements. At the same time, a circle of through holes 3a that penetrate the double-sided board is processed on the edge of each unit of the double-sided board. The through holes 3a are used to connect the circuit board and external components later. When processing blind holes 2a and through holes 3a, it is necessary to control parameters such as the diameter, rotation speed and feed speed of the drill bit to ensure the quality and position accuracy of the holes.

[0058] The upper and lower surfaces of the double-sided board 3 processed with the blind holes 2a and the through holes 3a are covered with a dry film 116 for pattern transfer. During the pattern transfer process, the desired circuit pattern is formed on the dry film 116 using photolithography technology, and at the same time, portions 2b and 3b not covered by the dry film are formed at the openings of the blind holes 2a and the through holes 3a. These portions not covered by the dry film will form copper-plated conductive holes and conductive through holes in the subsequent electroplating step.

[0059] Electroplating is performed to form copper-plated conductive holes 2c at the positions of blind holes 2a, and copper-plated conductive through holes 3c at the positions of through holes 3a. During the electroplating process, parameters such as the concentration, temperature, and current density of the electroplating solution need to be controlled to ensure the plating thickness and uniformity of the conductive holes 2c and conductive through holes 3c. At the same time, the electroplating time needs to be controlled to ensure that the depths of the conductive holes 2c and conductive through holes 3c meet the design requirements.

[0060] After the electroplating is completed, the second dry film pattern layer 116 is removed using a chemical solution to expose the un-electroplated portion of the copper foil layer 112 .

[0061] Finally, an etching solution is used to remove the portion of the copper foil layer 112 that is not covered by electroplating and dry film, exposing the circuit 1b and the conductive holes 2c and conductive through holes 3c. During the etching process, the concentration, temperature, and etching time of the etching solution need to be controlled to ensure the uniformity and accuracy of the etching. After the etching is completed, a PCB board with double-sided embedded circuits and conductive holes and conductive through holes is obtained.

[0062] As described above, the present invention first makes a single-layer circuit 1b on a thicker PCB single-sided board 1, and then presses the circuit 1b into an insulating film to obtain a single-sided buried circuit board 2, and then pastes two single-sided buried circuit boards 2 on a high-temperature resistant film 115 to obtain a double-sided buried circuit board 3, and makes a circle of copper-plated conductive through holes 3c on the edge of each unit of the double-sided buried circuit board 3, thereby improving the overall strength of the double-sided buried circuit board, and at the same time, makes copper-plated conductive blind holes 2c so that the circuits on the upper and lower boards form a loop. The insulating dielectric layer 110 of the single-sided buried circuit board 2 is thick and strong, which can avoid the warping of the board when the single-layer circuit 1b is made. In addition, the low-temperature pressing method is adopted to paste the two single-sided buried circuit boards 2 on a high-temperature resistant film 115, and the existing technology is not used for long-term hot pressing at a high temperature of ≥150 degrees, which can avoid the problem of board warping after hot pressing due to the asymmetry of the circuit 1b patterns of the two single-sided buried circuit boards 2.

[0063] In one embodiment, see Figures 1 to 6 Based on the contents of the above embodiment, this embodiment is further designed as follows: like Figures 1 to 6 As shown, preferably, the width of the circuit 1b is ≥7µm. In this way, the wiring density on the single-sided board 1 can be greatly improved by burying the circuit, thereby increasing the space utilization.

[0064] like Figures 1 to 6 As shown, preferably, the thickness of the insulating dielectric layer 110 is ≥300 µm, so that the single-sided buried circuit board 2 has good rigidity, avoiding the board warping when the single-layer circuit 1b is manufactured.

[0065] like Figures 1 to 6 As shown, preferably, the thickness of the copper foil layer 112 is H1, and 3µm≤H1≤12µm, so that the copper foil layer can be conveniently and evenly bonded to the temporary adhesive layer 111, and then easily removed by an etching solution after electroplating.

[0066] like Figures 1 to 6 As shown, preferably, the thickness of the insulating film layer 114 and the high temperature resistant adhesive layer 115 are both H2, and 10µm≤H2≤100µm, so that through holes or blind holes can be easily processed on the insulating film layer and the high temperature resistant adhesive layer while ensuring the strength of the insulating layer.

[0067] like Figures 1 to 6 As shown, preferably, the thickness of the line 1b is H3, and 5µm≤H3≤30µm, the diameters of the blind hole 2c and the through hole 3c are D1, and 50µm≤D1≤150µm, so that the current carrying capacity of the line can be guaranteed.

[0068] like Figures 1 to 6As shown, preferably, the temporary adhesive layer 111 in step one is a pyrolytic adhesive, so that in step six, the temporary adhesive layer 111 can be easily peeled off from the surface of the copper foil layer 112 by baking at 120 to 150 degrees for 30 seconds to 120 seconds.

[0069] like Figures 1 to 6 As shown, preferably, in step five, a vacuum laminating machine is used to pre-laminate and flatten the insulating film 114, and the pre-laminating and flattening temperature is 70-100°C, and the pre-laminating and flattening time is shorter than 120 seconds. In this way, it can be ensured that the temporary adhesive layer 111 remains sticky and will not peel off from the insulating medium layer 110.

[0070] like Figures 1 to 6 As shown, preferably, in step six, the single-sided embedded circuit board 2 is pressed onto the high-temperature resistant adhesive layer 115 using an ordinary laminating machine, and the laminating temperature is 20~100°C, and the laminating time is 30~120 seconds. In this way, it can be ensured that the single-sided embedded circuit board 2 is firmly bonded to the high-temperature resistant adhesive layer 115.

[0071] like Figures 1 to 6 As shown, preferably, in step seven, the temporary adhesive layer 111 loses its stickiness by baking the plate, and the baking temperature is 120-150°C, and the baking time is 30 seconds-120 seconds. In this way, a shorter baking time will not cause the plate to warp or deform.

[0072] like Figures 1 to 6 As shown, preferably, in step eight, the blind hole 2a and the through hole 3a are processed by laser ablation process, so that deformation of the adhesive layer caused by mechanical drilling can be avoided.

[0073] like Figures 1 to 6 As shown, preferably, in step 4 and step 11, an alkaline chemical solution is used to remove the first dry film pattern layer 113 and the second dry film pattern layer 116, so that it can be ensured that the alkaline chemical solution will not damage the electroplated area.

[0074] like Figure 5 As shown, preferably, the through holes made at the edge of each unit in step eight and step ten form a rectangle, and the side lengths L1 and L2 of the rectangle are both ≤15mm. In this way, a rivet-like structure is formed after the through holes are electroplated, which enhances the overall strength of the double-sided buried circuit board and avoids deformation of the board.

[0075] Compared with the prior art, this embodiment improves production efficiency and reduces costs. It uses processes such as laser ablation to process blind holes and through holes, and alkaline chemical solutions to remove dry film pattern layers, which not only improves production efficiency and processing accuracy, but also reduces material loss and processing costs that may be caused by traditional mechanical drilling. At the same time, the temporary adhesive layer 111 is removed using a pyrolysis adhesive and baking process, which simplifies the production process and further reduces production costs.

[0076] The insulating dielectric layer 110 is designed to have a thickness of ≥300µm, ensuring that the single-sided buried circuit board 2 has good rigidity and effectively avoiding the problem of board warping that may occur when making a single-layer circuit. In addition, the through holes made at the edge of each unit form a rectangular shape, forming a rivet-type structure, which further enhances the overall strength and stability of the double-sided buried circuit board 3 and improves the reliability and durability of the product.

[0077] The thickness of the copper foil layer 112 and the circuit 1b are precisely controlled to ensure that the circuit 1b has good conductivity and current carrying capacity. At the same time, the diameters of the blind holes and through holes are also optimized to ensure the electrical connectivity of the circuit 1b while avoiding the adverse effects of excessive hole diameters on the board strength and current distribution.

[0078] The insulating film and the high temperature resistant adhesive layer 115 are pressed together using a vacuum laminating machine and a common laminating machine, thereby ensuring the firmness and flatness of the pressing. The application of the laser ablation process avoids the deformation and precision loss of the adhesive layer that may be caused by mechanical drilling, thereby improving the processing precision and product quality.

[0079] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0080] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for manufacturing a PCB board with double-sided embedded circuits, characterized in that: The following steps are involved: Step 1: providing a PCB single-sided board (1), the single-sided board (1) comprising an insulating dielectric layer (110) and a temporary adhesive layer (111), the temporary adhesive layer (111) comprising two opposite upper surfaces and a lower surface, the lower surface of the temporary adhesive layer (111) being bonded to the upper surface of the insulating dielectric layer (110), and the upper surface of the temporary adhesive layer (111) being bonded to the copper foil layer (112); Step 2: performing pattern transfer on the surface of the copper foil layer (112) of the PCB to form a dry film pattern layer (113) on the surface of the copper foil layer (112); Step three: electroplating the portion (1a) of the copper foil layer (112) not covered by the dry film pattern layer (113) to form a circuit (1b); Step 4: removing the dry film pattern layer (113) using a chemical solution; Step 5: Laminating an insulating film (114) on the surface of the circuit (1b), and leveling the surface of the insulating film (114) to obtain a single-sided buried circuit board (2); Step six: laminating the two single-sided buried circuit boards (2) respectively onto the upper and lower surfaces of a high temperature resistant adhesive layer (115), and bonding the insulating adhesive film layers (114) of the two single-sided buried circuit boards (2) to the upper and lower surfaces of the high temperature resistant adhesive layer (115); Step seven: baking the board, the temporary adhesive layer (111) loses its stickiness and is separated from the surface of the copper foil layer (112), thereby obtaining a double-sided board (3) with embedded circuits on both sides; Step eight: processing a blind hole (2a) that does not penetrate the double-sided panel on the double-sided embedded circuit (3), and processing a circle of through holes (3a) that penetrate the double-sided panel at the edge of each unit of the double-sided panel; Step nine: Covering the upper and lower surfaces of the double-sided board (3) processed with the blind hole (2a) and the through hole (3a) with a dry film (116), performing pattern transfer, forming a portion (2b) not covered by the dry film at the opening position of the blind hole (2a), and forming a portion (3b) not covered by the dry film at the opening position of the blind hole (3a); Step ten: performing electroplating to form a copper-plated conductive hole (2c) at the position of the blind hole (2a), and forming a copper-plated conductive through hole (3c) at the position of the through hole (3a); Step 11: removing the dry film pattern layer (116) using a chemical solution; Step twelve: using an etching solution to remove the copper foil layer (112) to expose the circuit (1b).

2. A double-sided embedded circuit PCB according to claim 1, characterized in that: The width of the line (1b) is ≥ 7µm; The thickness of the insulating dielectric layer (110) is ≥ 300 µm; The copper foil layer (112) has a thickness of H1, and 3µm≤H1≤12µm.

3. A double-sided embedded circuit PCB according to claim 1, characterized in that: The thickness of the insulating adhesive film layer (114) and the high temperature resistant adhesive layer (115) are both H2, and 10µm≤H2≤100µm.

4. A double-sided embedded circuit PCB according to claim 1, characterized in that: The thickness of the circuit (1b) is H3, and 5µm≤H3≤30µm; The diameters of the blind hole (2c) and the through hole (3c) are both D1, and 50µm≤D1≤150µm.

5. The double-sided embedded circuit PCB according to claim 1, characterized in that: The temporary adhesive layer (111) in step 1 is a pyrolytic adhesive.

6. A double-sided embedded circuit PCB according to claim 1, characterized in that: In step 5, the insulating adhesive film (114) is pre-laminated and leveled using a vacuum laminating machine, and the pre-laminating and leveling temperature is 70-100° C., and the pre-laminating and leveling time is 30-120 seconds; In step six, a common laminating machine is used to laminar the single-sided embedded circuit board (2) onto the high temperature resistant adhesive layer (115), and the laminating temperature is 20-100° C. and the laminating time is 30-120 seconds; In step seven, the temporary adhesive layer (111) loses its stickiness by baking the plate, and the baking temperature is 120-150° C. and the baking time is 30-120 seconds.

7. A double-sided embedded circuit PCB according to claim 1, characterized in that: In step eight, the blind hole (2a) and the through hole (3a) are processed by laser ablation technology.

8. The double-sided embedded circuit PCB according to claim 1, characterized in that: Preferably, in step 4 and step 11, an alkaline chemical solution is used to remove the dry film pattern layer (113) and the dry film pattern layer (116).

9. The double-sided embedded circuit PCB according to claim 1, characterized in that: Preferably, the through holes made at the edge of each unit in step eight and step ten form a rectangle, and the side lengths L1 and L2 of the rectangle are both ≤15 mm.

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