High-layer high-density circuit board and preparation method thereof

Abstract

The invention discloses a high-layer high-density circuit board and a preparation method, and belongs to the technical field of circuit board manufacturing, and the preparation method comprises the steps: 1, drilling through holes in core boards L1-L2 and L9-L10 through a mechanical drilling mode, and carrying out the processing after drilling to form L2 and L9 circuit patterns; the core boards L3-L4 and the core boards L7-L8 are subjected to inner layer pattern and etching treatment to form L3 and L8 circuit patterns, then the core boards L1-L2 and the core boards L3-L4 are overlapped, the core boards L7-L8 and the core boards L9-L10 are overlapped, and an L1-L4 combined board and an L7-L10 combined board are formed after first pressing; the problems that a high-density circuit board is difficult to manufacture and high in manufacturing cost are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of circuit board manufacturing, and specifically relates to a high-layer and high-density circuit board and a preparation method thereof. Background Art

[0002] In the design and manufacture of modern electronic devices, high-density (HDI) circuit boards are favored for their compact space utilization and efficient circuit layout. This type of circuit board is usually designed with a stacked structure to maximize space utilization. During product development, according to design specifications, traditional manufacturing methods tend to use HDI Any layer technology. This technology covers the core processes of HDI, including key steps such as laser drilling, blind hole copper plating, and horizontal copper filling.

[0003] However, these advanced process steps require manufacturers to have high-end production equipment and superb technical capabilities. Unfortunately, not all circuit board manufacturers have such production conditions and technical strength. Although these high-precision equipment can ensure the quality and performance of the products, they also bring significant cost increases. In addition, these cost increases also limit the widespread application and development of high-density circuit boards.

[0004] In view of this, a more cost-effective solution is proposed in the hope of achieving results comparable to those of circuit boards manufactured by traditional high-precision equipment without relying on expensive equipment. Summary of the invention

[0005] In view of the above problems, the present invention provides a high-layer high-density circuit board and a preparation method thereof, which are used to solve the problems of difficulty in manufacturing high-density circuit boards and high manufacturing costs.

[0006] To achieve the above object, the technical solution adopted by the present invention is: A method for preparing a high-rise and high-density circuit board, comprising: Step 1: First, through holes are drilled in the core boards L1-L2 and L9-L10 by mechanical drilling, and then processed after drilling to form L2 and L9 circuit patterns; the core boards L3-L4 and L7-L8 are processed by inner layer patterns and etching to form L3 and L8 circuit patterns, and then the core boards L1-L2 and L3-L4 are overlapped, and the core boards L7-L8 and L9-L10 are overlapped, and after the first pressing, the L1-L4 combined board and the L7-L10 combined board are formed; Step 2: Drill through holes in the combined board L1-L4 by mechanical drilling, and process them after drilling to form the L4 circuit pattern, then form the L5 circuit pattern after the core board L5-L6 is processed by inner layer pattern and etching, and the core board L5-6 is overlapped with the combined core board L1-L4, and after a second pressing, the L1-L6 combined board is formed; Step 3: Drill holes through the combined boards L7-L10 obtained in step 1 and the combined boards L1-L6 obtained in step 2 again by mechanical drilling, and form the circuit patterns of L6 and L7 respectively after processing, and overlap the combined boards L1-L6 and L7-L10, and form the L1-L10 combined board after the third pressing.

[0007] As a further improvement of the above solution, the processing includes: copper deposition, full-board electroplating, outer layer graphics, plated holes, polishing, inner layer graphics, and inner layer etching.

[0008] As a further improvement of the above scheme, the L1-L10 combination board obtained in step 3 also needs to be drilled, copper plated, full-board electroplated, outer layer patterned, pattern electroplated, outer layer etched, and solder masked, text, gold plated, and formed to obtain the finished circuit board, and finally packaged after electrical testing and final inspection.

[0009] As a further improvement of the above solution, during the core plate pressing process, it is also necessary to compensate for the core plate drilling coefficient shape and measure the semi-finished product size coefficient to confirm whether the size is qualified.

[0010] In addition, a high-layer and high-density circuit board is provided, which is manufactured by the above method and includes a first core board group and a second core board group. The first core board group and the second core board group are pressed together by a dielectric layer, and the first core board group and the second core board group are connected by through holes. The through holes penetrate the first core board group and the second core board group. The first core board group and the second core board group are asymmetric structures.

[0011] As a further improvement of the above scheme, the first core plate group and the second core plate group are formed by pressing the core plate medium and the medium layer, and the first core plate group and the second core plate group are also respectively provided with blind holes penetrating the core plate medium and the medium layer, and the number of the blind holes is the same as the number of the core plate medium.

[0012] As a further improvement of the above solution, the surface of the core board medium has a metal layer, and the metal layer is connected with the through hole and the blind hole.

[0013] As a further improvement of the above solution, the thickness of the dielectric layer is 0.120 mm-0.125 mm; The thickness of the core medium is 0.20mm-0.28mm.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a method for manufacturing a high-rise and high-density circuit board. The method does not adopt traditional HDI technology and does not require the use of high-precision equipment for processing. The present invention adopts pressing, drilling and other methods to manufacture a circuit board comparable to that manufactured by traditional high-precision processes, which can effectively save manufacturing costs and solve the problem of traditional PCB companies realizing high-rise and high-density circuit board sample and small batch manufacturing without HDI equipment and technology. The method has the characteristics of low production cost and rapid response to customer needs.

[0015] 2. By using a single core board to manufacture a core board group, multiple combined boards can be processed in parallel. Each combined board is manufactured independently and then combined, which can reduce the time and cost of the entire circuit board manufacturing process; the independent manufacture of combined boards can easily control the quality and characteristics of each combined board, thereby better controlling the electrical performance of the entire circuit board.

[0016] 3. During the drilling process, the rack size is compensated to ensure that the circuit pattern on the core board is not damaged when the different layer boards are pressed and drilled, thereby preventing the product layers from being misaligned and causing short circuits, and also preventing the product size from being affected during other processing processes; the drilling size coefficient is adjusted and determined according to the number of pressing times, providing a basis for the product size processing accuracy, and can continuously detect the size of the semi-finished product until the finished product size is qualified, thereby improving the product quality.

[0017] 4. The processed circuit board is made of multiple core board groups pressed together as a whole. The pressing times are small and the size is easier to guarantee. The blind holes and through holes processed on the entire circuit board can also meet the requirements of circuit boards made with HDI technology. The structure of the circuit board can solve the problems of difficult product manufacturing and difficult product structure guarantee under the cooperation of corresponding processes. It is suitable for the processing and manufacturing of high-rise and high-density circuit boards with lower costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the state of the manufacturing process of the circuit board of the present invention; Figure 2 is a process flow chart of the present invention; Figure 3 It is a structural schematic diagram of a first embodiment of a circuit board of the present invention; Figure 4 It is a structural schematic diagram of a second embodiment of the circuit board of the present invention; Figure 5 It is a structural schematic diagram of a third embodiment of the circuit board of the present invention; Figure 6 Schematic diagram of the structure of the fourth embodiment of the circuit board of the present invention.

[0019] In the figure: 10, first core board group; 11, second core board group; 12, dielectric layer; 13, through hole; 14, blind hole; 15, core board dielectric; 16, isolation section. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solution, the present invention is described in detail below in conjunction with embodiments. The description in this section is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0021] See attached Figure 1-2 The specific scheme of this embodiment is: a method for preparing a high-layer high-density circuit board, comprising: Step 1: First, drill through holes in the core board L1-L2 and L9-L10 by mechanical drilling, and then perform copper deposition, full-board electroplating, outer layer graphics, hole plating, grinding, inner layer graphics, and inner layer etching to form L2 and L9 circuit graphics. Figure 1 (a); The core boards L3-L4 and L7-L8 are processed through inner layer patterns and etching to form L3 and L8 circuit patterns, and then the core boards L1-L2 and L3-L4 are overlapped, and the core boards L7-L8 and L9-L10 are overlapped. After the first pressing, the L1-L4 combined core board and the L7-L10 combined board are formed, as shown in FIG. Figure 1 (b); Step 2: Drill through holes in the combined board L1-L4 by mechanical drilling, and after drilling, perform copper deposition, full board electroplating, outer layer patterning, hole plating, grinding, inner layer patterning, and inner layer etching to form the L4 circuit pattern. Then, after the core board L5-L6 is processed by inner layer patterning and etching, the L5 circuit pattern is formed, and the core board L5-6 is overlapped with the combined core board L1-L4, and after a second pressing, the L1-L6 combined board is formed. Figure 1 (c); Step 3: Drill through holes in the combined boards L7-L10 obtained in step 1 and the combined boards L1-L6 obtained in step 2 again by mechanical drilling, and form the circuit patterns of L6 and L7 respectively after copper deposition, full-board electroplating, outer layer patterning, hole plating, grinding, inner layer patterning, and inner layer etching. The combined boards L1-L6 and L7-L10 are overlapped, and after the third pressing, the L1-10 combined board is formed. Figure 1 (d) The obtained L1-L10 combination board also needs to be drilled, copper plated, full-board electroplated, outer layer patterned, pattern electroplated, outer layer etched, and solder mask, text, gold plated, and formed to obtain the finished circuit board. Finally, it can be packaged after passing electrical testing and final inspection.

[0022] The manufacturing process of this circuit board mainly adopts the drilling method to directly produce through holes and blind holes on the pressed core board. The same circuit board can be processed without using high-precision equipment and processes. The circuit board produced at least has the same electrical performance as the circuit board processed by high-precision equipment and processes, which can save manufacturing costs, lower the manufacturing threshold, and promote the improvement of circuit boards. It is suitable for the processing and manufacturing of high-rise, high-density circuit boards with lower costs.

[0023] As a preferred embodiment of the above embodiment, since pressing is required during the processing, and since the core plate usually becomes smaller in size after high-temperature vacuum pressing, the drilling coefficient needs to be determined during the drilling process to achieve compensation for the size, and the drilling coefficient includes radial and latitudinal directions; the specific method for determining the drilling coefficient is: according to the design size of the core plate drilling, the radial drilling coefficient increases by 4%-5% on the basis of the design size for each additional pressing times of the core plate; the latitudinal drilling coefficient increases by 2%-3%.

[0024] At the same time, the semi-finished product size coefficient is measured to confirm whether the size is qualified; Specifically, since the product will have dimensional changes during the lamination process, usually the size after lamination will be smaller than before lamination. Therefore, in order to meet customer requirements for product size after multiple laminations and to prevent short circuits caused by misalignment between product layers, the semi-finished product needs to be enlarged; the number of laminations experienced by each core board is different, and the enlargement coefficient is the same. Other processing processes will also affect the size of the product, such as grinding after hole plating. After experiments, the enlargement coefficients are as follows: Taking the circuit board structure of this application as an example, under the structure of a 10-layer circuit board, the drilling coefficient and size measurement coefficient recording process of three pressing processes are as follows: Core board L1-2: After 3 times of lamination, drilling size coefficient: warp: 115%-118%; weft: 108%-110%. The film size of the inner layer pattern of L2 shall be based on the actual measurement of the semi-finished product before the inner layer pattern is exposed; Core board L3-4: The magnification factor of the inner layer pattern of L3 is consistent with that of the inner layer pattern of L2; Core board L9-10: After 2 times of lamination, drilling size coefficient: warp: 110%-112%; weft: 106%-108%. The film size of the inner layer pattern of L9 shall be based on the actual measurement of the semi-finished product before the inner layer pattern is exposed; Core board L7-8: The inner layer pattern magnification factor of L8 is consistent with the inner layer pattern magnification factor of L9.

[0025] After the first lamination, the semi-finished product L1-4 is formed. The size coefficient of the semi-finished product before the L4 inner layer pattern exposure is measured as follows: warp: 110%-112%; weft: 105%-107%; After the first lamination, the semi-finished product L7-10 is formed. The size coefficient of the semi-finished product before the L7 inner layer pattern exposure is measured as follows: warp: 105%-107%; weft: 103%-105%; Core board L5-6: The magnification factor of the inner layer pattern of L5 is consistent with that of the inner layer pattern of L4; After the second lamination, the L1-6 semi-finished product is formed. The size coefficient of the semi-finished product before the L6 inner layer pattern exposure is measured as follows: warp: 105%-107%; weft: 103%-105%; Above, the size coefficients of L1-6 and L7-10 semi-finished products are kept consistent; the size of L6 and L7 inner layer graphic films is designed with warp direction: 105%-107%; weft direction: 103%-105%; After the third pressing, the L1-10 semi-finished product is formed. The dimensional coefficients after pressing are measured: warp: 101%-102%; weft: 100%-102%.

[0026] According to the above-mentioned production process records, since no pressing process is performed after the third pressing process, the product size is basically formed, so it can be directly considered as the finished product measurement size coefficient, and the semi-finished product measurement size coefficient after the third pressing is within the control range of the finished product measurement size coefficient, and it is judged as a qualified product.

[0027] By adopting the above manufacturing process, the present application manufactures a high-density circuit board, such as Figure 3 , 4 Two circuit boards with similar structures are shown, which include a first core board group 10 and a second core board group 11. The first core board group 10 and the second core board group 11 are pressed together via a dielectric layer 12, and the dielectric layer 12 is made of PP material. The first core board group 10 and the second core board group 11 are connected via a through hole 13, and the through hole 13 runs through the first core board group 10 and the second core board group 11. The first core board group 10 and the second core board group 11 are asymmetric structures. Specifically, the first core board group 10 includes core boards L1-L6, and the second core board group 11 includes L7-L10.

[0028] Among them, the first core plate group 10 and the second core plate group 11 are formed by pressing the core plate medium 15 and the medium layer 12, 5 core plate mediums 15 are provided, 4 medium layers 12 are provided, and the first core plate group 10 and the second core plate group 11 are respectively provided with blind holes 14 penetrating the core plate medium 15 and the medium layer 12, and the number of the blind holes 14 is the same as the number of the core plate medium 15; the surface of the core plate medium 15 has a metal layer, and the metal layer is connected with the through hole 13 and the blind hole 14.

[0029] The thickness of the dielectric layer 12 is 0.120 mm-0.125 mm; the thickness of the core dielectric 15 is 0.20 mm-0.28 mm.

[0030] As another embodiment, please refer to the attached Figure 5 As shown, in this embodiment, an isolation segment 16 is provided in the L8-L10 layer of the formed circuit board. The isolation segment 16 is specifically a part without metal connection. The isolation segment 16 connects the dielectric layer 12 and the core board dielectric 15. The number of connected dielectric layers 12 and core board dielectrics 15 is determined according to the structure of the circuit board. It is mainly for some circuit boards with special surfaces. In the process of circuit connection, the circuit structure is changed by insulating different circuit layers so that the circuit board can play a better effect.

[0031] Specifically, during the manufacturing process, after the last pressing is completed and before the copper deposition process of forming the through hole 13, the drilling bit used is a drill bit slightly larger than the aperture of the through hole 13, and a hole is drilled on the circuit board. Figure 6 After reaching the depth, the drill is withdrawn, and then without moving the drill press (without leaving the coordinate system of the drill press), an isolating agent is injected into the drill hole, pressurized and dried, that is, an isolating layer is formed in the drill hole to prevent the formation of a copper film on the hole wall during the copper deposition process. Then, after replacing the drill bit for forming the through hole 13, drilling is continued at the original drilling position until it is completely penetrated, and then the drill hole can be subjected to copper deposition, electroplating and other treatments.

[0032] Figure 6 Another circuit board structure is shown, that is, another isolation segment 16 is arranged on the other side of the isolation segment 16 in the above embodiment. This structural processing method can install the circuit board on a rotatable mounting platform, exposing the drilling position during installation, and switching the drilling position can be done by flipping 180 degrees, or using an opposite drill bit for processing.

[0033] It should be noted that, in this article, the terms include, contain or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. Specific examples are used in this article to illustrate the principle and implementation of the technical solution of the present invention. The above examples are only used to help understand the method of the present invention and its core idea. The above is only a preferred implementation of the present invention. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements, modifications or changes can be made, and the above technical features can also be combined in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the invention to other occasions without improvement, should be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a high-rise and high-density circuit board, characterized in that: include: Step 1: First, through holes are drilled in the core boards L1-L2 and L9-L10 by mechanical drilling, and then processed after drilling to form L2 and L9 circuit patterns; the core boards L3-L4 and L7-L8 are processed by inner layer patterns and etching to form L3 and L8 circuit patterns, and then the core boards L1-L2 and L3-L4 are overlapped, and the core boards L7-L8 and L9-L10 are overlapped, and after the first pressing, the L1-L4 combined board and the L7-L10 combined board are formed; Step 2: Drill through holes in the combined board L1-L4 by mechanical drilling, and process them after drilling to form the L4 circuit pattern, then form the L5 circuit pattern after the core board L5-L6 is processed by inner layer pattern and etching, and the core board L5-6 is overlapped with the combined core board L1-L4, and after a second pressing, the L1-L6 combined board is formed; Step 3: Drill holes through the combined boards L7-L10 obtained in step 1 and the combined boards L1-L6 obtained in step 2 again by mechanical drilling, and form the circuit patterns of L6 and L7 respectively after processing, and overlap the combined boards L1-L6 and L7-L10, and form the L1-L10 combined board after the third pressing.

2. A method for preparing a high-rise and high-density circuit board according to claim 1, characterized in that: The processing includes: copper deposition, full board electroplating, outer layer graphics, hole plating, polishing, inner layer graphics, and inner layer etching.

3. The method for preparing a high-rise and high-density circuit board according to claim 1, characterized in that: The L1-L10 combination board obtained in step 3 also needs to be drilled, copper plated, full-board electroplated, outer layer patterned, pattern electroplated, outer layer etched, and solder masked, text, gold plated, and formed to obtain the finished circuit board. Finally, it can be packaged after passing electrical testing and final inspection.

4. The method for preparing a high-rise and high-density circuit board according to claim 1, characterized in that: During the core board pressing process, it is also necessary to compensate for the core board drilling coefficient shape, and at the same time measure the semi-finished product size coefficient to confirm whether the size is qualified.

5. A high-density high-layer circuit board manufactured by the method according to any one of claims 1 to 4, characterized in that: The invention comprises a first core plate group (10) and a second core plate group (11), wherein the first core plate group (10) and the second core plate group (11) are pressed together via a dielectric layer (12), and the first core plate group (10) and the second core plate group (11) are connected via a through hole (13), wherein the through hole (13) penetrates the first core plate group (10) and the second core plate group (11), and the first core plate group (10) and the second core plate group (11) are of an asymmetric structure.

6. The circuit board according to claim 5, characterized in that: The first core plate group (10) and the second core plate group (11) are formed by pressing together a core plate medium (15) and a medium layer (12), and the first core plate group (10) and the second core plate group (11) are respectively provided with blind holes (14) penetrating the core plate medium (15) and the medium layer (12), and the number of the blind holes (14) is the same as the number of the core plate medium (15).

7. The circuit board according to claim 6, characterized in that: The surface of the core plate medium (15) has a metal layer, and the metal layer is connected to the through hole (13) and the blind hole (14).

8. The circuit board according to claim 5, characterized in that: The thickness of the dielectric layer (12) is 0.120 mm-0.125 mm; The thickness of the core medium (15) is 0.20 mm to 0.28 mm.

Images