KR102275538B1 - Surface Treatment Method of Stainless Steel Plate for Using FPCB Reinforcement - Google Patents

Abstract

The present invention relates to a SUS (Steel Use Stainless) plate surface treatment method for FPCB (Flexible Printed Circuit Board).
A protective vinyl for plating is attached to one side of the SUS plate for FPCB included in the mobile phone camera module to prevent plating, and the plating layer formed of nickel and tin is stably and uniformly plated on the other side. to improve the flatness, no scratches, and only one side is plated so that the surface roughness of the other side that is not plated is maintained below a certain value, suggesting a surface treatment method for manufacturing SUS plate for FPCB with excellent surface roughness do.

Description

SUS plate surface treatment method for FPCB reinforcement {Surface Treatment Method of Stainless Steel Plate for Using FPCB Reinforcement}

The present invention relates to a method for surface treatment of a SUS (Steel Use Stainless) plate for reinforcing FPCB (Flexible Printed Circuit Board), and more particularly, to prevent plating on one side of the SUS plate for reinforcing FPCB included in a mobile phone camera module. Prevents plating by occupying a protective vinyl for plating, and improves flatness by stably and uniformly plating the properties of the plating layer formed of nickel and tin on the other side. The other side, which is not treated, relates to a surface treatment method for manufacturing a SUS plate for FPCB reinforcement with excellent surface roughness by maintaining the surface roughness below a certain value.

In general, in portable home appliances such as mobile phones, MP3, USB terminal memory, CD players, cameras, etc., and portable products such as cell phones, stainless steel (SUS) plate parts are used in consideration of the high quality, durability and decorativeness of the product. It is used to manufacture and use stainless steel (SUS) plate parts or cases, and it is customary to plating the surface of parts or cases in consideration of color, durability, corrosion resistance, and decorative properties such as color and gloss, and FPCB (Flexible Printed Circuit Board) is a printed circuit board that has flexibility to bend freely unlike general rigid printed circuit boards (PCBs). It has folds or hinges or various devices that require multi-line wiring, for example, laptops and mobile phones. , an electronic notebook, personal information terminal, digital camera, etc., are widely used in electronic devices having an electrical connection between component modules or where multiple data wiring is required.

Meanwhile, with the rapid development of electronic communication technology in recent years, electronic communication devices such as mobile phones, notebook computers, and digital cameras are equipped with various multimedia functions. For example, a small camera module which is an image input means as a core component for realizing such multimedia functions. is growing in importance. In particular, the demand for high-definition camera modules is increasing according to the desire of consumers to enjoy clear multimedia of various contents while having a small size for easy portability of smart phones.

Accordingly, in order to guarantee the stability of its operation, it is very important to supply the power and transmit the image signal at the same time as the FPCB. Since the PCB strip is very thin and flexible, the image sensor chips for each FPCB are mounted according to the flatness. Bonding defects were frequent, which eventually resulted in a problem that led to a defect in the camera module.

In order to solve this problem, with the recent rapid development of semiconductor integrated circuits, the importance of FPCBs, which are easy to embed in complex and narrow spaces, has increased due to the development of surface mount technology to mount small chips and their components. A plan is being promoted to slim the overall thickness by mounting the image sensor chip on the SUS plate after bonding the plate to the place where the chip rises, such as the image sensor of the FPCB, and for the production of SUS plate with improved flatness and excellent surface roughness. Various studies are being conducted.

As a related prior document, Korean Patent Publication No. 10-1694782, published on January 11, 2017 (hereinafter referred to as [Patent Document 1]) discloses a method for manufacturing an etched substrate for a flexible circuit board. The [Patent Document 1] relates to the manufacture of a flexible printed circuit board (FPCB), and more particularly, in the manufacture of an etching sus plate attached to a flexible printed circuit board, a non-bridge type (Non -Bridge type) A method for etching a sus plate plated with nickel (Ni) on the surface of sus so as not to leave a nickel (Ni) residue, and using this to etch a sus plate and a conductive adhesive film (CBF: A method of laminating an etched substrate for a flexible circuit board and a conductive adhesive film, which can greatly reduce the manufacturing time and cost of the flexible circuit board by arranging a plurality of conductive bonding films) on an XY matrix and then laminating them simply and accurately in one process. is disclosed about

However, in [Patent Document 1], the properties of the plating layer formed of nickel and tin cannot be stably and uniformly plated, and the surface roughness of the SUS plate cannot be maintained. There is a difficult problem.

Republic of Korea Patent Publication No. 10-1694782, published 2017. 01. 11.

In the present invention, in order to solve this conventional problem, a protective vinyl for plating is attached to one side of the SUS plate material for reinforcing FPCB included in the mobile phone camera module so that plating does not proceed, and nickel and tin are formed on the other side. The plating method of the SUS plate material for FPCB reinforcement that improves the flatness and does not cause scratches by stably and uniformly plating the properties of the plating layer, and maintains the surface roughness of the SUS plate below a certain value for the unplated surface will provide

The present invention for achieving the above object is in the SUS plate surface treatment method for FPCB reinforcement, (a) adhering a protective vinyl for plating on one surface of the SUS plate (S600);

(b) removing contaminants from the surface of the SUS plate through electrolytic degreasing and plating the other surface of the SUS plate to which the protective vinyl for plating is not adhered with nickel and tin (S700); and (c) removing the protective vinyl for plating adhered to one surface of the SUS plate (S800).

Preferably, the step of adhering the protective vinyl for plating (S600) is after laminating the protective vinyl for plating on the surface of the SUS plate, the adhesion machine pressure is 4.5±1.0 kg/cm 2 , the roller temperature 50±5° C., and the roller speed is 0.2 to 0.5 By closely adhering at m/min, the protective vinyl for plating is adhered to one surface of the SUS plate.

More preferably, the protective vinyl for plating in the adhesion step (S600) of the protective vinyl for plating is characterized in that it consists of an adhesive strength of 10 gf / in.

Also preferably, the protective vinyl for plating in the step of attaching the protective vinyl for plating (S600) is characterized in that it consists of PET Film 75㎛, Silicone Adhesive 20㎛, PET Film Release Liner 25㎛.

Also preferably, the plating step (S700) is performed on the other side of the SUS plate to which the protective vinyl for plating is not attached, and a degreasing step (S710) of removing contaminants on the surface of the SUS plate through electrolytic degreasing; In order to improve the plating adhesion of the surface of the SUS plate, a current of 50±10 [A] is applied to the plating solution containing nickel chloride at a concentration of 24±5 g/L and hydrochloric acid 10±5 g/L for 30±10 seconds (sec). Strike nickel plating step of performing additive plating (S720); The surface of the SUS plate on which the strike nickel plating has been performed is applied to a plating solution containing nickel sulfamic acid at a concentration of 64±10 g/L with a current of 50±10 [A] for 60±10 seconds (sec) to proceed with plating. Nickel plating step (S730); The surface of the SUS plate on which the sulfamic acid nickel plating has been performed is applied to a plating solution containing tin at a concentration of 30±10 g/L with a current of 25±8 [A] for 25±10 seconds (sec) to perform plating on tin (Sn). ) plating step (S740); and a water washing step (S750) of removing contaminants by spraying pure distilled water on the tin-plated SUS plate surface with a final washing end resistance of 0.1 MΩ/cm or more.

First, in the present invention, the SUS plate surface treatment method for reinforcing FPCB is to attach a protective vinyl for plating to one side of the SUS plate for reinforcing the FPCB included in the mobile phone camera module so that only one side is plated, and secondly, the other side of SUS for reinforcing the FPCB. It improves the flatness by stably and uniformly plating the properties of the plating layer formed of nickel and tin, and does not cause scratches. Third, one side of the SUS for reinforcing FPCB that is not plated has excellent surface roughness. There is a synergistic effect that can manufacture a SUS plate for FPCB reinforcement having a.

Effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those of ordinary skill in the art from the following description.

1 is a flowchart for explaining a method for surface treatment of a SUS plate for FPCB reinforcement according to the present invention;
Figure 2 is an embodiment in which the SUS plate is mounted on the FPCB,
3 is a block diagram of a protective vinyl for plating according to the present invention,
4 is a schematic conceptual diagram of a method for surface treatment of a SUS plate for reinforcing FPCB according to the present invention;
5 is a photograph showing a camera module to which the present invention is applied;
6 is a view showing the other side (bottom side) plated with nickel and tin and one side (top side) that are not plated with nickel and tin of the SUS plate manufactured by the method for surface treatment of the SUS plate for FPCB reinforcement according to the present invention;
7 is a view showing an applied embodiment of the SUS plate manufactured by the SUS plate surface treatment method for FPCB reinforcement according to the present invention.

Hereinafter, a preferred embodiment of the SUS plate surface treatment method for FPCB reinforcement according to the present invention will be described in detail with reference to the accompanying drawings. The specific structures or functions of the present invention described below are only exemplified to describe embodiments according to the concept of the present invention, and the embodiments according to the present invention may be embodied in various forms, and the implementations described herein It should not be construed as being limited to the examples.

First, referring to FIG. 1, it is a method for surface treatment of a SUS plate for reinforcing FPCB according to the present invention,

1. Pretreatment process (S100)

The pretreatment process is a process of washing the surface of the SUS plate by removing the oxide film, organic foreign substances, and oil present on the surface of the SUS plate with an alkaline chemical.

In the pretreatment process, the surface of the SUS plate is corroded by immersing the SUS plate in an electrolytic bath, and the surface of the SUS plate can be washed by removing the oxide film, organic foreign substances and oil present on the surface.

For example, by immersing the SUS plate in an electrolytic bath containing an alkaline chemical containing at least one selected from sodium hydroxide (NaOH) and a surfactant at a temperature of 25 to 45° C. for 10 to 30 seconds, the SUS plate surface It can remove oxide film, organic foreign matter and oil.

2. DRY FILM coating process (S200)

The dry film coating is a process of coating the dry film on the surface of the pre-treated SUS plate.

In the dry film coating process, a known dry film can be coated on the surface of the pretreated SUS plate by using a roller, for example, after laminating the photosensitive film on the surface of the SUS plate, the temperature of the upper and lower rollers is 100±5 ℃, by pressing at a roller pressure of 4.5±1.0 kg/cm 2 and a roller driving speed of 0.5 to 1.0 m/min, the DRY FILM can be coated on the surface of the pretreated SUS plate.

3. Exposure process (S300)

The exposure process is the same as the patterning of the master film by laminating a master film patterned in a certain shape on the SUS plate coated with the dry film, and then irradiating UV on the surface of the SUS plate for a certain time. It is a process of selectively curing the dry film.

In the exposure process, UV is selectively irradiated according to the patterning shape of the master film, so that the UV-irradiated DRY FILM portion may be photocured, and the UV-irradiated DRY FILM portion may not be photocured.

In the exposure process, after laminating the master film patterned in a certain shape on the SUS plate coated with the dry film, the exposure amount 45±8mJ/cm2, the vacuum pressure -90KPa or more, and the vacuum time of 20±10 seconds (sec) As a result, by irradiating UV to the surface of the SUS plate, the dry film can be selectively cured in the same form as the patterning of the master film.

4. Development process (S400)

The developing process is a process of dissolving the dry film that is not photocured with a developer of sodium carbonate (Na ₂ CO _{3 ).}

That is, in the exposure process, the UV-irradiated dry film part is photocured, and the UV-irradiated dry film part is not photocured. In the developing process, the UV-irradiated dry film part is not dissolved in the developer. It can be removed by decomposing in the developing solution of the dry film area that is not irradiated with UV.

In the exposure process, the _{photosensitive film that is not photocured can be dissolved with a developer of sodium carbonate (Na 2} CO ₃ ), and the temperature of the developer is 25±5° C., a driving speed of 5 to 7 m/min, and a drying temperature of 120± By carrying out the process conditions of 10 ℃, it can be decomposed and removed in the developing solution of the dry film area that is not irradiated with UV.

5. Etching process (S500)

The etching process is a process of patterning the surface of the SUS plate in a predetermined shape by etching the surface of the SUS plate using an etchant.

In the etching process, the surface of the SUS plate can be patterned in a predetermined shape using an etching solution made of ferric chloride (FeCl3). The surface of the SUS plate on which the dry film is present is not etched and the dry film is not present. The surface of the SUS plate may be selectively etched to pattern the surface of the SUS plate in a predetermined shape.

In the etching process, an etching solution made of ferric chloride (FeCl3) may be used, and the etching solution temperature is 50±5°C, the specific gravity of the etching solution is 36 to 46 Be, the peeling temperature is 50±10°C, the drying temperature is 150±10°C, and the etching pressure is By performing under the process conditions of 2.0±1.0 kg/cm 2 and the final shredder resistance of 1 MΩ/cm or more, the surface of the SUS plate with the dry film is not etched and the surface of the SUS plate without the dry film is selectively can be etched.

6. Protective vinyl adhesion process for plating (S600)

The step of adhering the protective vinyl for plating is a step of adhering the protective vinyl for plating to one surface of the surface of the SUS plate.

In the protective vinyl adhesion process for plating, the plating protection vinyl can be adhered in close contact with the surface of the SUS plate using an adhesion device. For example, after the protective vinyl for plating is laminated on the surface of the SUS plate, the pressure of the upper adhesion group is 4.5 By closely contacting at ±1.0 kg/cm 2 , a roller temperature of 50 ± 5° C. and a roller speed of 0.2 to 0.5 m/min, the protective vinyl for plating can be adhered to one surface of the SUS plate surface.

7. Plating process (S700)

The plating process is a process of plating the SUS plate with nickel (Ni) and tin (Sn) on the other side except for one side to which the protective vinyl for plating is adhered.

The plating process may include (1) degreasing step (2) nickel (Ni) plating step (3) nickel sulfamic acid (Ni) plating step (4) tin (Sn) plating step (5) washing with water. .

(1) degreasing step

The degreasing step removes contaminants on the surface of the SUS plate through the electrolytic degreasing step.

(2) Nickel (Ni) plating step

The nickel (Ni) plating step is a strike nickel plating performed to improve the plating adhesion to the SUS plate, and 50 ± 10 [A] of nickel chloride 24 ± 5 g / ℓ, hydrochloric acid 10 ± 5 g / ℓ in a plating bath. Apply current for 30±10 seconds (sec) to proceed with plating.

(3) Nickel Sulfamate Plating Step

The nickel sulfamate plating step is performed to improve the hardness, abrasion resistance, and tensile strength of the SUS plate, and a current of 50±10 [A] is applied to a plating bath of 64±10 g/ℓ for 60±10 seconds. Apply plating for (sec).

(4) Tin (Sn) plating step

The tin (Sn) plating step is carried out to improve solderability of the SUS plate, and a current of 25±8 [A] is applied to a plating bath of 30±10 g/ℓ for 25±10 seconds (sec). Proceed with plating.

(5) washing step

The water washing step is a final water washing step of removing contaminants with pure distilled water under the condition of a final washing end resistance of 0.1 MΩ/cm or more.

8. Protective vinyl removal process for plating (S800)

After the plating process step (S700) is completed, the protective vinyl for plating is removed from one surface of the SUS plate to which the protective vinyl for plating is adhered. Protection for plating so that the surface is not deformed when the protective vinyl for plating is removed This is a step to complete the surface treatment of the SUS plate for FPCB reinforcement by removing the vinyl.

In addition, the detailed steps of the plating process are (1) degreasing step (2) water washing step 3 step (3) hydrochloric acid treatment (neutralization) step (4) water washing step 3 step (5) strike Ni plating step (6) water washing step 1 step (7) Ni sulfamic acid plating step (8) Washing with water 3 steps (9) Sn plating step (10) Washing with water 3 steps (11) 3rd sodium phosphate step (12) 2 steps of washing with water (13) To the final washing step can be performed.

Referring to FIG. 2, it shows an embodiment in which the SUS plate for FPCB reinforcement is mounted, and FIG. 2 (a) is an embodiment in which the SUS plate 20 is mounted on the FPCB 10, while improving the flatness of the FPCB. A SUS plate is coupled to increase heat dissipation efficiency, and FIG. 2(b) shows another example showing that the shape of the SUS plate 20-1 may also vary according to the circuit pattern of the FPCB 10-1.

Referring to FIG. 3, it is a configuration diagram of a protective vinyl for plating according to the present invention, and has a thickness of PET Film (32) 75㎛, Silicone Adhesive (30) 20㎛, PET Film Release Liner (31) 25㎛, Silicone If the adhesive force between the adhesive and the SUS plate is high, deformation may occur when the PET film is removed after plating, so the adhesive force ([gf] gram force per [inch] inch) of the vinyl for plating protection is 8 to 12 gf/in. , preferably composed of 10 gf/in.

4, it shows a schematic conceptual diagram of a method for surface treatment of a SUS plate for FPCB reinforcement according to the present invention, and a protective vinyl for plating is attached to one side (upper surface) of the surface of the SUS plate to prevent plating, and the SUS plate It is technically characterized to be plated with nickel and tin only on the other side (lower surface) of the surface.

Referring to FIG. 5 , as a photograph showing a camera module to which the present invention is applied, the SUS plate for FPCB reinforcement applied to the camera module has excellent surface roughness, the property of the plating layer is stable, and the need for a uniformly plated SUS plate is required

Referring to Figure 6, it shows the SUS plate manufactured by the method for surface treatment of the SUS plate for FPCB reinforcement according to the present invention, Figure 6 (a) shows the SUS plate of the other side (lower surface) plated with nickel and tin, Fig. 6(b) is a photo showing the SUS plate on one side (upper side) that is not plated with nickel and tin. The surface roughness of the SUS plate applied to the FPCB through single-sided plating is excellent, and the properties of the plating layer are stable and uniform. It is characterized in that it is plated.

In addition, the surface roughness of one side of the SUS plate according to the present invention, that is, the surface that is not plated with nickel and tin, is technically characterized in that it has a surface roughness of Rmax 0.18μ or less.

Referring to FIG. 7, it is a view showing an applied embodiment of the SUS plate manufactured by the SUS plate surface treatment method for FPCB reinforcement according to the present invention, the nickel and tin-plated SUS plate surface 21 of FIG. The other side (lower side) is coupled to the FPCB (10), and one side (upper side), which is the non-plated SUS plate side 22, is coupled to the SUS plate as shown in FIG. 7(c), so that the SUS plate has excellent surface roughness. It shows that the FPCB 15 to which the plate is bonded is formed.

The above description is merely illustrative of the technical idea of the present invention, and the present invention can be applied to a SUS plate surface treatment method for FPCB reinforcement by a person skilled in the art by various modifications, and is technically easy It should be recognized that the scope of the technology to transform it to be within the scope of the present patent.

10: Flexible Printed Circuit Board (FPCB)
10-1: FPCB variant
15: FPCB with SUS plate combined
20: SUS (Steel Use Stainless) plate
20-1: SUS plate modification example
21: Nickel and tin plated SUS plate side
22: Non-plated SUS plate side
30: Silicone Adhesive
31: PET Film Release Liner
32: PET Film

Claims (5)

In the SUS plate surface treatment method for FPCB reinforcement,
(a) adhering a protective vinyl for plating to one surface of the SUS plate (S600);
(b) removing contaminants from the surface of the SUS plate through electrolytic degreasing and plating the other surface of the SUS plate to which the protective vinyl for plating is not adhered with nickel and tin (S700); and
(c) including a step (S800) of removing the protective vinyl for plating adhered to one surface of the SUS plate,
The step of adhering the protective vinyl for plating (S600) is, after laminating the protective vinyl for plating on the surface of the SUS plate, the adhesion machine pressure is 4.5±1.0 kg/cm 2 , the roller temperature 50±5° C. Adhering the protective vinyl for plating to one surface of the SUS plate by
In the protective vinyl adhesion step (S600) for plating, the protective vinyl for plating has an adhesive strength of 8 to 12 gf/in,
The plating step (S700) is,
A degreasing step (S710) of removing the contaminants on the surface of the SUS plate through electrolytic degreasing and proceeding to the other side of the SUS plate to which the protective vinyl for plating is not adhered;
In order to improve the plating adhesion of the surface of the SUS plate, a current of 50±10 [A] is applied to the plating solution containing nickel chloride at a concentration of 24±5 g/L and hydrochloric acid 10±5 g/L for 30±10 seconds (sec). Strike nickel plating step of performing additive plating (S720);
The surface of the SUS plate on which the strike nickel plating has been performed is applied to a plating solution containing nickel sulfamic acid at a concentration of 64±10 g/L with a current of 50±10 [A] for 60±10 seconds (sec) to proceed with plating. Nickel plating step (S730);
The surface of the SUS plate on which the sulfamic acid nickel plating has been performed is applied to a plating solution containing tin at a concentration of 30±10 g/L with a current of 25±8 [A] for 25±10 seconds (sec) to perform plating on tin (Sn). ) plating step (S740); and
SUS plate surface treatment method for FPCB, characterized in that it comprises a water washing step (S750) of removing contaminants by spraying pure distilled water on the tin-plated SUS plate surface under the condition of a final washing end resistance of 0.1 ㏁ / cm or more.
delete delete According to claim 1,
The protective vinyl for plating in the step of adhering the protective vinyl for plating (S600) is a SUS plate surface treatment method for FPCB, characterized in that it consists of PET Film 75㎛, Silicone Adhesive 20㎛, PET Film Release Liner 25㎛.
delete

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