Processing method for locally thickening inner signal layer as power supply layer

Abstract

The invention discloses a processing method for locally thickening an inner signal layer as a power supply layer in the field of circuit board processing, which comprises the following steps of: selecting a power supply area on a first surface or / and a second surface of an inner substrate, and taking the first surface or / and the second surface except the power supply area as a circuit area, etching an inner layer pattern which is designed in advance on the circuit area; processing a seed layer, and pressing a dry film on the seed layer; removing the dry film on the power supply area, and electroplating copper in the power supply area; sequentially removing the dry film and the seed layer on the circuit area, and then dispensing on the circuit area; and pressing the plurality of inner-layer substrates processed in the steps together to form the core plate. According to the processing method provided by the invention, the power supply area is processed by electroplating copper in the circuit area for thickening, and the power supply area does not need to be arranged on the other layer of the circuit area, so that the processing steps are reduced, the processing method is simple, the operation is performed on the surface of one inner-layer substrate, and the processing efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing, and more particularly to a manufacturing method for locally thickening an inner signal layer to create a power layer. Background Technology

[0002] like Figure 5 As shown, the existing circuit board has a double-layer structure for the power layer and signal layer. If one layer is the power layer, the signal layer needs to be placed on another layer. The outer layer connects the two layers through PTH holes. When there are multiple signal layers, high stacking is required. The PTH holes processed need to be precisely aligned between the two layers. The stacking method is complicated and difficult to process. Moreover, the double-layer structure makes the circuit board thicker and cannot meet the usage requirements. Summary of the Invention

[0003] The purpose of this invention is to provide a processing method for locally thickening an inner signal layer to form a power layer. This method involves electroplating copper in a selected area of ​​the inner substrate to form a power layer, eliminating the need for a separate power layer.

[0004] To solve the above technical problems, the following technical solution is adopted: In a first aspect, the present invention provides a method for fabricating a power layer by locally thickening an inner signal layer, comprising the following steps: A power supply area is selected on the first surface and / or the second surface of the inner layer substrate, and the area of ​​the first surface and / or the second surface other than the power supply area is the circuit area. A pre-designed inner layer pattern is etched on the circuit area. A seed layer is processed on the first surface and / or the second surface, and a dry film is pressed onto the surface of the seed layer; Remove the dry film on the power supply area and electroplate copper on the power supply area; The dry film and seed layer on the circuit area are removed sequentially, and adhesive is applied to the circuit area to obtain the inner layer substrate after the power layer is processed. Several inner layer substrates after processing the power supply layer are pressed together to form a core board.

[0005] Optionally, the seed layer is processed by vacuum sputtering.

[0006] Optionally, the adhesive thickness is determined based on the height of the electroplated copper layer. The difference between the height of the adhesive after dispensing on the circuit area and the height of the power supply area after electroplating copper is within 3 mils. Theoretically, the height of the adhesive surface after dispensing is the same as that of the power supply area after electroplating copper. However, due to the existence of errors, the height of the adhesive surface is controlled during dispensing. The height of the adhesive surface can be slightly lower than that of the power supply area after electroplating copper, with an error range of 0-3 mils.

[0007] Optionally, the seed layer thickness ranges from 500 to 1000 nanometers. The seed layer is a conductive thin film formed by vacuum sputtering. The main purpose of the seed layer is to connect the interior of the inner substrate with the external environment, ensuring that copper can be plated during electroplating in the power supply area.

[0008] Optionally, the electroplated copper is 1.8-2.2 ounces, preferably 2 ounces.

[0009] Optionally, the thickness difference of the copper-plated surface in the power supply area is within 0.1 mils to ensure plating uniformity.

[0010] Alternatively, the dry film on the circuit area can be removed by chemical etching.

[0011] In a second aspect, the present invention provides a circuit board, including a core board, wherein the core board is manufactured using the processing method described in the first aspect for locally thickening the inner signal layer to form a power layer.

[0012] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The processing method provided by the present invention creates a power area by electroplating copper to thicken the circuit area. The power area does not need to be set on another layer of the circuit area, and there is no need to process holes for electrical connection between the two layers, reducing processing steps. The processing method is simple and can be operated on the surface of an inner layer substrate, improving processing efficiency. At the same time, setting the power area and the circuit area in one layer also reduces the thickness of the circuit board. Attached Figure Description

[0013] Figure 1 This is one of the flowcharts illustrating the processing method of the present invention; Figure 2 This is a second schematic diagram of the processing method of the present invention; Figure 3 This is a side view of the arrangement of the power supply area and the circuit area on the inner substrate in the processing method of the present invention. Figure 4 This is a top view of the arrangement of the power supply area and circuit area on the inner substrate in the processing method of the present invention. Figure 5 This is a schematic diagram of the prior art regarding the arrangement of the power layer and signal layer in the background art of this invention.

[0014] Explanation of reference numerals in the attached figures: 1. Inner substrate; 2. Circuit area; 3. Power area; 4. Seed layer; 5. Dry film; 6. Core board. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use.

[0016] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0017] Example 1

[0018] This embodiment provides a fabrication method for locally thickening an inner signal layer to create a power layer, such as... Figure 1 , Figure 2 As shown, it includes the following steps: The first step is to transfer the pattern of the inner layer substrate 1. Based on the circuit structure, the power area 3 and the circuit area 2 on the inner layer substrate 1 are determined. The power area 3 and the circuit area 2 are on one surface of the inner layer substrate 1. Then, the pre-designed inner layer pattern is etched in the circuit area 2. The second step is to vacuum sputter the inner layer substrate 1 to form a seed layer 4 on the side of the inner layer substrate 1 where the inner layer pattern is formed. The seed layer 4 is attached to all surfaces of the inner layer substrate 1 that are in contact with air, and the seed layer 4 is also attached to the surface and sidewalls of the inner layer pattern. The seed layer 4 is a conductive thin film formed on the inner layer substrate 1 by vacuum sputtering.

[0019] The third step is to cover the inner substrate 1 with a film and press a dry film 5 onto the surface of the seed layer 4. The dry film 5 can protect the circuit structure on the circuit area 2 and prevent copper from being plated on the circuit area 2 when the power area 3 is electroplated in the subsequent steps.

[0020] The fourth step is to remove the dry film 5 located in the power area 3 by chemical etching; at this time, the power area 3 only has the seed layer 4 and no dry film 5, while the circuit area 2 has both the seed layer 4 and the dry film 5. The fifth step is to electroplate the inner substrate 1 with copper on the power area 3 where there is no dry film 5, so that the surface of the power area 3 has a certain thickness of copper. Step 6: Remove the film from the inner substrate 1 by etching the dry film 5 of the circuit area 2 with chemical solution. Step 7: Inner substrate SPS, the seed layer 4 of the circuit area 2 is removed by chemical etching. Step 8: Apply adhesive to the inner substrate 1. Use an adhesive application device to fill the circuit area 2 with adhesive. After filling, the adhesive surface can be slightly lower than the power area 3 after copper plating. When filling the adhesive, the recess of the circuit area 2 relative to the power area 3 should be controlled within 3 microns. Step 9: Inner layer substrate 1 is pressed together. According to the circuit structure sequence, several inner layer substrates 1 processed in the above steps are pressed together using adhesive sheets and a hot press to form core board 6.

[0021] The outer layer processing involves the core board 6 after processing. The outer layer processing includes a series of conventional processing procedures such as pretreatment, interlayer electrical connection, and outer layer circuit fabrication, which will not be described in detail in this embodiment.

[0022] In the processing of the core board 6, a seed layer 4 is set in the second step. The seed layer 4 is a conductive thin film with a thickness between 500-1000 nanometers. The seed layer 4 enables the successful electroplating of copper on the power supply area 3. The seed layer 4 is processed by vacuum sputtering. Vacuum sputtering is a physical vapor deposition technique that uses plasma to bombard a solid target material, causing the target atoms to be ejected and deposited onto the surface of the substrate. The substrate surface is the inner layer substrate 1 in this embodiment. The conductive seed layer 4 is formed on the inner layer substrate 1 by vacuum sputtering, and the seed layer 4 connects the power supply area 3 to the external environment.

[0023] In this embodiment, the copper plating on the power layer is 2 ounces. During copper plating, the surface variation of the copper plating in power region 3 is within 0.1 mils to ensure the uniformity of the surface of power region 3. Adhesive is applied to circuit region 2, and the surface after adhesive application is slightly lower than that of power region 3.

[0024] In some embodiments, the inner layer substrate 1 is processed using steps 1-9 described above, according to the circuit board requirements and circuit structure design.

[0025] like Figure 3, Figure 4 As shown, the processing method provided in this embodiment creates the power supply area 3 by thickening it. The power supply area 3 and the circuit area 2 are placed on the surface of an inner substrate 1. The power supply area 3 does not require an additional layer, simplifying the processing, reducing circuit board manufacturing costs, and allowing for a reduction in circuit board thickness to meet usage requirements. During processing, the surface difference of the power supply area 3 after copper plating is within 0.1 mils, ensuring plating uniformity.

[0026] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for fabricating a power layer by locally thickening an inner signal layer, characterized in that, Includes the following steps: A power supply area is selected on the first surface and / or the second surface of the inner layer substrate, and the area of ​​the first surface and / or the second surface other than the power supply area is the circuit area. A pre-designed inner layer pattern is etched on the circuit area. A seed layer is processed on the first surface and / or the second surface, and a dry film is pressed onto the surface of the seed layer; Remove the dry film on the power supply area and electroplate copper on the power supply area; The dry film and seed layer on the circuit area are removed sequentially, and adhesive is applied to the circuit area to obtain the inner layer substrate after the power layer is processed. Several inner layer substrates after processing the power supply layer are pressed together to form a core board.

2. The processing method for locally thickening an inner signal layer to create a power layer according to claim 1, characterized in that, The seed layer is processed using vacuum sputtering.

3. The processing method for locally thickening an inner signal layer to create a power layer according to claim 1, characterized in that, The adhesive thickness is determined based on the height of the electroplated copper layer, and the difference between the height of the adhesive layer after application and the height of the power supply area after electroplating copper is within 3 mils.

4. The processing method for locally thickening an inner signal layer to create a power layer according to claim 1, characterized in that, The thickness of the seed layer ranges from 500 to 1000 nanometers.

5. The processing method for locally thickening an inner signal layer to create a power layer according to claim 1, characterized in that, The electroplated copper is 1.8-2.2 ounces.

6. The processing method for locally thickening an inner signal layer to create a power layer according to claim 1, characterized in that, The thickness difference of the surface of the power supply area after copper plating is within 0.1 mil.

7. The processing method for locally thickening an inner signal layer to create a power layer according to claim 1, characterized in that, The dry film on the circuit area is removed by chemical etching.

8. A circuit board, characterized in that, The invention includes a core board, which is manufactured using the processing method described in any one of claims 1-7 for locally thickening the inner signal layer to form a power layer.

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