Manufacturing method for improving foaming and layering of electromagnetic shielding film

Abstract

The invention relates to a circuit board processing method, in particular to a manufacturing method for improving foaming and layering of an electromagnetic shielding film, which comprises the following steps of: after the circuit board is pretreated, pasting a protective film on the surface of the circuit board, and baking the protective film, so that the protective film is cured on the surface of the circuit board; a filler is arranged with the through hole of the circuit board as the center, and the filler is pre-baked; the pre-baked filler is exposed and developed, so that the filler is only reserved in a preset range with the through hole as the center; an electromagnetic shielding film is arranged on the surface of the circuit board, the electromagnetic shielding film covers at least part of the protective film and all the filler, and post-baking is conducted on the filler; and post-processing the circuit board. According to the method provided by the invention, the filler is arranged in the through hole of the circuit board before the electromagnetic shielding film is pasted, so that the bad defect of bubble layering of the electromagnetic shielding film in the subsequent process of reflow oven and the like is avoided.

Description

Technical Field

[0001] The invention relates to a circuit board processing method, in particular to a manufacturing method for improving blistering and delamination of an electromagnetic shielding film. Background Art

[0002] The description in this section merely provides background information related to the present disclosure and does not constitute prior art.

[0003] At present, there is a circuit board with an electromagnetic shielding film. The circuit board is relatively thick, and a through hole is set in the area covered by the electromagnetic shielding film to achieve the connection needs of the circuit. In the process of processing the above-mentioned circuit board, since there is gas in the through hole, the subsequent steps such as attaching the electromagnetic shielding film and transferring pressure and reflowing furnace may cause the electromagnetic shielding film to have the defect of bubble stratification due to the influence of hot and cold changes and pressure.

[0004] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0005] The purpose of the present invention is to provide a method for improving the blistering and stratification of electromagnetic shielding films. Before attaching the electromagnetic shielding film, a filler can be set in the through hole of the circuit board to avoid the undesirable defect of blistering and stratification of the electromagnetic shielding film in subsequent processes such as a reflow furnace.

[0006] In order to achieve the above-mentioned object, the present invention discloses the following method for improving the blistering and delamination of an electromagnetic shielding film, which is used to avoid the phenomenon of blistering and delamination at the through hole of the circuit board after the electromagnetic shielding film is attached to the circuit board. The method for improving the blistering and delamination of the electromagnetic shielding film comprises:

[0007] After pre-processing the circuit board, a protective film is attached to the surface of the circuit board, and the protective film is baked so that the protective film is solidified on the surface of the circuit board;

[0008] Arranging a filler with the through hole of the circuit board as the center, and pre-baking the filler;

[0009] Exposing and developing the pre-baked filler so that the filler remains only within a preset range centered on the through hole;

[0010] The electromagnetic shielding film is arranged on the surface of the circuit board, the electromagnetic shielding film covers at least a part of the protective film and all of the filler, and the filler is post-baked;

[0011] The circuit board is post-processed.

[0012] As a further description of the above technical solution, the circuit board has a first surface and a second surface arranged opposite to each other, and the protective film includes a first protective film and a second protective film, the first protective film is attached to the first surface of the circuit board, and the second protective film is attached to the second surface of the circuit board, the first protective film has a first opening, and the second protective film has a second opening.

[0013] As a further description of the above technical solution, the through hole of the circuit board is located at the first opening of the first protective film on the first side of the circuit board and is not covered by the first protective film, and the through hole of the circuit board is covered by the second protective film on the second side of the circuit board.

[0014] As a further description of the above technical solution, the through hole of the circuit board is located at the first opening of the first protective film on the first side of the circuit board and is not covered by the first protective film, and the through hole of the circuit board is located at the second opening of the second protective film on the second side of the circuit board and is not covered by the second protective film.

[0015] As a further description of the above technical solution, the electromagnetic shielding film includes a first electromagnetic shielding film and a second electromagnetic shielding film, the first electromagnetic shielding film is attached to the first surface of the circuit board, and the second electromagnetic shielding film is attached to the second surface of the circuit board.

[0016] As a further description of the above technical solution, after the step of "arranging the electromagnetic shielding film on the surface of the circuit board", it also includes the steps of plasma treatment, reinforcement, testing, and molding of the circuit board.

[0017] As a further description of the above technical solution, the step of "pre-processing the circuit board" includes the steps of cutting, drilling and circuit processing the circuit board.

[0018] As a further description of the above technical solution, the filler is configured as solder resist ink, and the solder resist ink is configured to overflow the outer edge of the through hole at one end of the through hole of the circuit board that is not covered by the protective film.

[0019] By means of the above technical solution, the beneficial effects of the present invention are as follows:

[0020] The manufacturing method for improving the blistering and stratification of the electromagnetic shielding film of the present invention can be carried out by setting a filler in the through-hole of the circuit board before attaching the electromagnetic shielding film, exposing and developing the filler to form a dense covering in the through-hole of the circuit board, thereby removing the gas in the original through-hole and avoiding the undesirable defect of blistering and stratification of the electromagnetic shielding film on the outer surface of the circuit board during the subsequent attaching of the electromagnetic shielding film and the operation of the reflow furnace, thereby improving the finished product quality of the circuit board.

[0021] To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and description and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 It is a schematic diagram of a circuit board of a method for improving blistering and delamination of an electromagnetic shielding film provided in an embodiment of this specification;

[0024] In the figure:

[0025] 1. Circuit board; 11. Through hole;

[0026] 2. protective film; 21. first protective film; 22. second protective film;

[0027] 3. Filling;

[0028] 4. Electromagnetic shielding film; 41. First electromagnetic shielding film; 42. Second electromagnetic shielding film. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this specification.

[0030] The following is an explanation of the embodiments of the present invention through specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed in various ways based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted according to actual sizes. It is stated in advance. The following embodiments will further explain the relevant technical contents of the present invention in detail, but the disclosed contents are not intended to limit the scope of protection of the present invention.

[0031] It should be understood that, although the terms "first", "second", "third", etc. may be used herein to describe various components or signals, these components or signals should not be limited by these terms. These terms are mainly used to distinguish one component from another component, or one signal from another signal. In addition, the term "or" used herein may include any one or more combinations of the associated listed items depending on the actual situation.

[0032] See also Figure 1 , is a method for improving the blistering and delamination of the electromagnetic shielding film of this embodiment, which is used to prevent the blistering and delamination at the through hole of the circuit board 1 after the electromagnetic shielding film 4 is attached to the circuit board 1, wherein the method for improving the blistering and delamination of the electromagnetic shielding film 4 includes:

[0033] After the circuit board 1 is pre-treated, a protective film 2 is attached to the surface of the circuit board 1, and the protective film 2 is baked so that the protective film 2 is solidified on the surface of the circuit board 1;

[0034] The filler 3 is arranged at the center of the through hole 11 of the circuit board 1, and the filler 3 is pre-baked;

[0035] Exposing and developing the pre-baked filler 3 so that the filler 3 is only retained within a preset range centered on the through hole 11, and post-baking the filler 11;

[0036] An electromagnetic shielding film 4 is arranged on the surface of the circuit board 1, and the electromagnetic shielding film 4 covers at least a part of the protective film 2 and all of the filler 3;

[0037] The circuit board 1 is post-processed.

[0038] In the above process, firstly, a corresponding circuit board 1 substrate to be processed is selected, which is set as a flexible circuit board in this embodiment. First, after cutting the circuit board 1, a hole is drilled at the corresponding position of the circuit board 1, and then the drilled circuit board 1 is pre-treated by electroplating and copper is electroplated to metalize the hole wall, and then a corresponding circuit is made. Then, a protective film 2 is attached to the surface of the pre-treated circuit board 1, and the protective film 2 is baked so that the protective film 2 is solidified on the surface of the circuit board 1. Specifically, the protective film 2 may have an opening at the position of the through hole 11 of the circuit board 1, and then, a filler 3 is poured into the through hole 11 of the circuit board 1 from the position of the opening, so that the filler 3 completely fills at least the gap in the through hole 11 and may slightly overflow, and then the filler is exposed to achieve preliminary curing, and developed to achieve shaping, and finally, it is completely cured at the through hole 11 of the circuit board 1 by post-baking, so that the through hole of the circuit board 1 is filled solid. After the filling material 3 is disposed, an electromagnetic shielding film 4 is attached to the surface of the circuit board 1 , so that the electromagnetic shielding film 4 covers a predetermined area of ​​the circuit board 1 , including the through hole 11 area having the filling material 3 .

[0039] Through the treatment of the above method, after the electromagnetic shielding film 4 is affixed, the original through hole 11 of the circuit board 1 is replaced by a solid cured filler 11, which replaces the original gap. Therefore, in subsequent operations such as the reflow furnace, the electromagnetic shielding film on the outer surface of the circuit board 1 is prevented from having bubble stratification due to changes in the air pressure in the gap or air crossflow in the gap. By filling the through hole 11, the surface problems of the thicker circuit board 1 product are reduced, thereby improving the product yield.

[0040] For further information, see Figure 1 The circuit board 1 has a first surface and a second surface that are opposite to each other, and the protective film 2 includes a first protective film 21 and a second protective film 22. The first protective film 21 is attached to the first surface of the circuit board 1, and the second protective film 22 is attached to the second surface of the circuit board 1. The first protective film 21 has a first opening, and the second protective film 22 has a second opening. In one embodiment, it can be seen Figure 1 The position of the through hole 11 of the right circuit board 1 is that the through hole 11 of the circuit board 1 is located at the first opening of the first protective film 21 on the first side of the circuit board 1 and is not covered by the first protective film 21. The through hole 11 of the circuit board 1 is covered by the second protective film 22 on the second side of the circuit board 1. That is to say, in this embodiment, when the through hole 11 is filled with the filler 3, one end of the through hole 11 on the second side of the circuit board 1 has been filled with the second protective film 22 to form a blind hole. Therefore, it is only necessary to fill the blind hole and allow the first opening side of the first protective film 21 to have a part of the overflow filler 3, and confirm that the first opening position is also sealed by the filler 3.

[0041] In another embodiment, see Figure 1 The through hole 11 on the left side of the circuit board 1 is located at the first opening of the first protective film 21 on the first side of the circuit board 1 and is not covered by the first protective film 21. The through hole 11 on the second side of the circuit board 1 is located at the second opening of the second protective film 22 and is not covered by the second protective film 22. That is to say, during the filling process of the filler 3, the through hole 11 here is still in a completely through state. Therefore, the through hole 11 can be completely filled from top to bottom with the help of the filler 3, so that both ends of the through hole 11 have some overflowing filler 3, and it is confirmed that the first opening position and the second opening position are both sealed by the filler 3.

[0042] Based on the above-mentioned embodiment, both the first side and the second side of the circuit board 1 have circuit settings and processing. In this regard, the electromagnetic shielding film 4 includes a first electromagnetic shielding film 41 and a second electromagnetic shielding film 42. The first electromagnetic shielding film 41 is attached to the first side of the circuit board 1, and the second electromagnetic shielding film 42 is attached to the second side of the circuit board 1. In this embodiment, the filler 3 in the through hole 11 may be in direct contact with the electromagnetic shielding film 4 at both ends, or in contact with the electromagnetic shielding film 4 at one end. As long as it can be ensured that there is no gap for accommodating air at any position between the electromagnetic shielding film 4 and the through hole 11, air crossflow caused by temperature changes and the formation of bubbles between the electromagnetic shielding film 4 and the circuit board 1 can be avoided.

[0043] Furthermore, after the step of "arranging the electromagnetic shielding film 4 on the surface of the circuit board 1", the circuit board 1 is also subjected to the steps of plasma, reinforcement, testing, and molding. Specifically, the purpose of the plasma is to further clean the surface of the circuit board 1 to prevent stains and debris from affecting the tight adhesion of the electromagnetic shielding film 4. The purpose of this step is to make the surface of the circuit board 1 in a relatively clean state before the electromagnetic shielding film 4 is attached. Of course, the surface of the circuit board after plasma can also be baked to make it in a dry state, thereby improving the long-term stability of the bonding. The testing, molding and other steps are to detect the circuit board 1 to ensure that it meets the factory requirements.

[0044] Furthermore, in the step of "pre-processing the circuit board 1", the steps of cutting, drilling, and circuit processing the circuit board 1 are included. It has been described in the previous invention embodiment that before the protective film is attached to the circuit board 1, the raw material (such as the copper clad board) needs to be processed into the required size by cutting, and the through hole 11 is punched at the corresponding position according to the circuit requirements, and the corresponding circuit is processed based on the through hole 11.

[0045] The filler 3 is configured as solder resist ink, and the solder resist ink is configured to overflow the outer edge of the through hole 11 of the circuit board 1 at one end that is not covered by the protective film 2. Specifically, the solder resist ink has good electrical insulation performance, is easy to process and solidify, is easy to remove and fix, has good chemical resistance and heat resistance, and is suitable for removing and replacing the air in the through hole 11 in this embodiment.

[0046] The contents disclosed above are only preferred feasible embodiments of the present invention, and are not intended to limit the scope of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention's specification and drawings are included in the scope of the present invention.

[0047] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0048] Although the present application has been described through embodiments, those skilled in the art will appreciate that there are many modifications and changes to the present application without departing from the spirit of the present application. It is intended that the attached embodiments include these modifications and changes without departing from the present application.

Claims

1. A method for improving the blistering and delamination of an electromagnetic shielding film, which is used to prevent the blistering and delamination of the through holes of the circuit board after the electromagnetic shielding film is attached to the circuit board, characterized in that: The manufacturing method for improving the blistering and delamination of the electromagnetic shielding film comprises: After pre-processing the circuit board, a protective film is attached to the surface of the circuit board, and the protective film is baked so that the protective film is solidified on the surface of the circuit board; Arranging a filler with the through hole of the circuit board as the center, and pre-baking the filler; Exposing and developing the pre-baked filler so that the filler remains only within a preset range centered on the through hole, and post-baking the filler; The electromagnetic shielding film is arranged on the surface of the circuit board, and the electromagnetic shielding film covers at least a part of the protective film and all of the filler; The circuit board is post-processed.

2. The method for improving blistering and delamination of an electromagnetic shielding film according to claim 1, characterized in that: The circuit board has a first surface and a second surface arranged opposite to each other, and the protective film includes a first protective film and a second protective film, the first protective film is attached to the first surface of the circuit board, the second protective film is attached to the second surface of the circuit board, the first protective film has a first opening, and the second protective film has a second opening.

3. The method for improving blistering and delamination of an electromagnetic shielding film according to claim 2, characterized in that: The through hole of the circuit board is located at the first opening of the first protective film on the first side of the circuit board and is not covered by the first protective film, and the through hole of the circuit board is covered by the second protective film on the second side of the circuit board.

4. The method for improving blistering and delamination of an electromagnetic shielding film according to claim 2, characterized in that: The through hole of the circuit board is located at the first opening of the first protective film on the first side of the circuit board and is not covered by the first protective film. The through hole of the circuit board is located at the second opening of the second protective film on the second side of the circuit board and is not covered by the second protective film.

5. The method for improving blistering and delamination of an electromagnetic shielding film according to claim 2, characterized in that: The electromagnetic shielding film includes a first electromagnetic shielding film and a second electromagnetic shielding film. The first electromagnetic shielding film is attached to the first surface of the circuit board, and the second electromagnetic shielding film is attached to the second surface of the circuit board.

6. The method for improving blistering and delamination of an electromagnetic shielding film according to claim 1, characterized in that: After the step of "arranging the electromagnetic shielding film on the surface of the circuit board", the steps of performing plasma, pasting reinforcement, testing, and molding on the circuit board are also included.

7. The method for improving blistering and delamination of an electromagnetic shielding film according to claim 1, characterized in that: The step of "pre-processing the circuit board" includes the steps of cutting, drilling and circuit processing the circuit board.

8. The method for improving blistering and delamination of an electromagnetic shielding film according to claim 1, characterized in that: The filler is configured as solder resist ink, and the solder resist ink is configured to overflow the outer edge of the through hole at one end of the through hole of the circuit board that is not covered by the protective film.

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