Method for manufacturing super-multilayer PCB (Printed Circuit Board) by using sintered copper slurry

Abstract

The invention discloses a method for manufacturing a super-multilayer PCB (Printed Circuit Board) by using sintered copper slurry, relates to PCB manufacturing, and provides a scheme for solving the problem of the yield of the super-multilayer PCB in the prior art. Pressing a certain number of double-layer circuit substrates into a daughter board; preparing a plurality of daughter boards, wherein a corresponding through hole is formed in the vertical position of each daughter board; and pre-cured copper paste is used as a channel for electrical conduction of all the through holes after the sub-stacks are stacked and aligned. The method has the advantages that the limitation of dimension factors such as distance d and plate thickness on the preparation of the through hole is avoided through the design of the sub-plates of the multiple substrates. And the problem of through hole alignment deviation caused by too many factor boards can be avoided by connecting the through holes of the daughter boards in a copper paste pre-plugging manner. Meanwhile, the size limitation of the inner plate is avoided, and the layer number limitation is also avoided. By using the method, the PCB with 30 layers or more layers can be prepared.

Description

Technical Field

[0001] The present invention relates to a PCB manufacturing process, and in particular, to a method for manufacturing an ultra-multi-layer PCB using sintered copper paste. Background Art

[0002] With the development of electronic products, PCB printed circuit boards are continuously developing towards higher layer numbers, smaller micro distances, and smaller volumes, posing great challenges to traditional PCB manufacturing methods. The original production process cannot meet the needs of current high-end PCB manufacturing. The traditional method for manufacturing ultra-multi-layer PCBs uses the N*X equal-layer method. N refers to a double-layer circuit substrate, as Figure 1 shown. X refers to X number of Ns, as Figure 2 shown.

[0003] This equal-layer method is limited by the product size. For example, the distance d from the outer via 10 to the inner conductor cannot be less than 0.5 mm. The board thickness needs to be ≥3.0 mm, and the minimum hole diameter needs to be ≥0.25 mm to be manufactured using the conventional equal-layer method. Moreover, it is impossible to achieve high-layer and micro-hole high-end PCB boards. Taking a 30-layer PCB board as an example, 14 substrate sheets need to be combined and pressed. If the size such as the distance d is less than 0.5 mm or the board thickness is less than 3.0 mm during product design, this cannot be completed by conventional means.

[0004] If the ultra-multi-layer board is simply divided into several sub-boards for pressing, each sub-board includes a certain number of substrates. There are corresponding disclosed solutions in the prior art for this method, but the alignment effect of the vias in each sub-board still cannot meet the requirements of high-end PCBs with small micro distances and small volumes, and it is prone to open circuits, reducing the yield rate. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for manufacturing an ultra-multi-layer PCB using sintered copper paste to solve the problems existing in the above prior art.

[0006] In the method for manufacturing an ultra-multi-layer PCB using sintered copper paste according to the present invention, a certain number of double-layer circuit substrates are pressed into sub-boards;

[0007] A number of such sub-boards are prepared, and each sub-board is provided with corresponding vias in the vertical position;

[0008] Pre-cured copper paste is used as the electrical conduction channel for all vias after the sub-boards are stacked and aligned.

[0009] Welding rings are provided at both ends of the vias in each sub-board, and the welding rings are electrically connected to the copper layer in the vias;

[0010] Except for the sub-board at the topmost layer, a PP film is laid above each sub-board; a PET film is laid on the PP film; the PET film and the PP film on the pad are drilled by laser to obtain laser holes; copper paste is injected into the laser holes; after the copper paste is pre-cured, the PET film is removed; the sub-boards provided with copper paste are stacked in sequence, and the sub-board at the topmost layer is stacked at the topmost layer; all the sub-boards are pressed together to obtain the ultra-multi-layer PCB.

[0011] The diameter of the laser hole is 80 - 120 μm.

[0012] The thickness of the PET film is 70 - 140 μm.

[0013] The height of the copper plug in the laser hole is 40 - 80 μm higher than the upper surface of the PP film.

[0014] The pressing temperature of the sub-board is 190 °C.

[0015] The pressing time of the sub-board is 60 minutes.

[0016] In the method for manufacturing an ultra-multi-layer PCB by sintering copper paste according to the present invention, the advantages are that the sub-board design of multiple substrates avoids the limitations of size factors such as distance d and board thickness on the preparation of through-holes. The method of connecting the through-holes of each sub-board by pre-filling copper paste can avoid the problem of through-hole alignment deviation caused by too many sub-boards. At the same time, it circumvents the inner board size limitation and also circumvents the layer number limitation. Using this method, a PCB with 30 layers or more can be prepared. Brief Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of a double-layer circuit substrate.

[0018] Figure 2 is a schematic structural diagram of an ultra-multi-layer PCB in the prior art.

[0019] Figure 3 is the process schematic of the method described in the present invention Figure 1 .

[0020] Figure 4 is the process schematic of the method described in the present invention Figure 2 .

[0021] Figure 5 is the process schematic of the method described in the present invention Figure 3 .

[0022] Figure 6 is the process schematic of the method described in the present invention Figure 4 .

[0023] Reference Signs:

[0024] 10 - Through-hole, 11 - Solder Ring, 12 - Copper Paste. Detailed implementation mode

[0025] In the method for manufacturing a super multi-layer PCB using sintered copper paste according to the present invention, a certain number of double-layer circuit boards are pressed into sub-boards. A plurality of the sub-boards are prepared, and each sub-board is provided with corresponding through holes in the vertical position. The pre-cured copper paste is used as the channel for electrical conduction of all through holes after the sub-boards are stacked and aligned.

[0026] Solder rings are provided at both ends of the through holes in each sub-board, and the solder rings are electrically connected to the copper layer in the through holes, as Figure 3 shown.

[0027] Except for the topmost sub-board, a PP film is laid above each sub-board. A PET film with a thickness of 70-140 μm is laid on the PP film. The PET film and the PP film on the pads are drilled by laser to obtain laser holes with a diameter of 80-120 μm. Copper paste is injected into the laser holes, so that the height of the copper filling in the laser holes is 40-80 μm higher than the upper surface of the PP film, as Figure 4 shown.

[0028] After the copper paste is pre-cured, the PET film is removed. The sub-boards provided with copper paste are stacked in sequence, and the topmost sub-board is stacked on the top layer, as Figure 5 shown.

[0029] All the sub-boards are pressed at 190 °C, and the pressing time is maintained for 60 minutes to obtain the super multi-layer PCB, as Figure 6 shown.

[0030] For those skilled in the art, various corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. A method for making an ultra-multilayer PCB using sintered copper paddle, wherein a certain number of double-layer circuit substrates are pressed into a sub-board; Prepare a plurality of sub-plates, each of which is provided with a corresponding through hole at a vertical position; It is characterized in that The pre-cured copper paste is used as a channel for electrical conduction of all through holes after the sub-assemblies are stacked and aligned.

2. According to claim 1, a method for manufacturing a super-multilayer PCB using a sintered copper paddle is characterized in that: Both ends of the through hole in each daughter board are provided with solder rings, and the solder rings are electrically connected to the copper layer in the through hole; Except for the sub-board located on the top layer, a PP film is laid on each sub-board; a PET film is laid on the PP film; a laser is used to drill holes in the PET film and the PP film on the pad to obtain laser holes; copper paste is injected into the laser holes; the PET film is removed after the copper paste is pre-cured; the sub-boards provided with copper paste are stacked in sequence, and the sub-board located on the top layer is stacked on the top layer; all the sub-boards are pressed together to obtain the super-multilayer PCB.

3. According to claim 2, a method for manufacturing a super-multilayer PCB using a sintered copper paddle is characterized in that: The diameter of the laser hole is 80-120 μm.

4. According to claim 2, a method for manufacturing a super-multilayer PCB using a sintered copper paddle is characterized in that: The PET film has a thickness of 70 to 140 μm.

5. The method for manufacturing a super-multilayer PCB using a sintered copper paddle according to claim 3, characterized in that: The copper thickness of the laser hole plug is 40 to 80 μm higher than the upper surface of the PP film.

6. The method for manufacturing a super-multilayer PCB using a sintered copper paddle according to claim 2, characterized in that: The daughter board pressing temperature is 190℃.

7. The method for manufacturing a super-multilayer PCB using a sintered copper paddle according to claim 2, characterized in that: The sub-board pressing time is 60 minutes.

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