Black plating process for shell of camera module

Abstract

The invention provides a camera module shell black plating process which comprises the following steps: after a jig is placed in a sputter coating machine, respectively taking trititanium pentoxide, chromium metal and tantalum metal as cathode targets; the method comprises the following steps: vacuumizing a coating machine to 5 * 10 <-3 > Pa, injecting argon gas, ionizing the argon gas, coating by taking trititanium pentoxide as a cathode target at the coating current of 180mA, introducing nitrogen gas at the moment that the ratio of argon gas to nitrogen gas is 6: 1, coating by taking metal tantalum as a cathode target, adjusting the coating current to 350mA, introducing oxygen gas again, and coating by taking titanium dioxide as a cathode target at the moment that the ratio of argon gas to nitrogen gas is 6: 1. At the moment, the ratio of argon to nitrogen to oxygen is 6: 1: 1, metal chromium serves as a cathode target, coating is conducted finally, and the coating current is adjusted to be 480 mA; the coating thickness of the trititanium pentoxide layer is 380 nm, the coating thickness of the chromium nitride layer is 480 nm, and the coating thickness of the tantalum oxide layer is 210 nm; according to the method, various plating forms are adopted, and the density and internal stress of the film layer are adjusted by adjusting the concentration of sputtering gas and sputtering current, so that the condition of black film splitting is reduced, and the yield is improved.

Description

Technical Field

[0001] The invention relates to the field of sputtering coating, and in particular to a black coating process for a camera module housing. Background Art

[0002] like Figure 6 The camera module shown is usually used in periscope cameras. The exterior is metal, and the mouth is equipped with a filter. When light enters the filter, if the edge is not black, there will be light reflection, which will affect the imaging and produce an aperture. The mouth needs to be plated black to prevent the subsequent surface from having an aperture. There are two methods of black plating in the prior art: 1. Silk screen printing, 2. Black film plating. The silk screen printing method has many disadvantages. The color of the silk screen printing is not black enough, and there will still be light reflection, which affects the imaging. The black film plating method usually uses the sputtering method. However, in the existing sputtering process, argon gas and chrome silicon target materials are usually used for coating. However, due to the large internal stress of the chrome coating, the black film is easy to fall off after verification, and the finished product is low. In addition, in the process, since the coating is partially coated, it is necessary to use a jig to block it. Each product needs to be glued or, the efficiency is extremely low, the preparation time is long, and there is a gap in the window part where the plating is easy. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a black plating process for a camera module housing, comprising the following steps:

[0004] S1: Take the camera module substrate and perform ultrasonic cleaning to keep the surface clean.

[0005] S2: Take the jig, place the camera module on the jig, and press the camera module tightly through the jig cover, leaving the coating position exposed; and preheat the camera module substrate to 80-100°C;

[0006] S3: After placing the fixture in the sputtering coating machine, titanium pentoxide, metal chromium, and metal tantalum are respectively taken as cathode targets;

[0007] S4: Vacuum the coating machine to 5*10 -3 Pa, first inject argon gas, ionize the argon gas, and first use titanium pentoxide as the cathode target for coating, the coating current is 180mA, then introduce nitrogen gas, at this time the ratio of argon gas to nitrogen gas is 6:1, then use metal tantalum as the cathode target for coating, and adjust the coating current to 350mA, introduce oxygen gas again, at this time the ratio of argon gas, nitrogen gas and oxygen gas is 6:1:1, and finally use metal chromium as the cathode target for coating, and adjust the coating current to 480mA; the coating thicknesses are 380nm for titanium pentoxide layer, 480nm for chromium nitride layer, and 210nm for tantalum oxide layer respectively;

[0008] S5: Maintain the pressure for 30 minutes, release the air and take out the material.

[0009] Preferably, during the coating process, the jig is driven to rotate at a speed of 20 r / min through a driving device.

[0010] Preferably, the fixture includes a circular base and a circular upper cover, a plurality of positioning posts are provided between the circular base and the circular upper cover, a plurality of square sunken grooves are evenly arranged on the circular base, the square sunken grooves are used to place the camera module, a protrusion is provided on the square sunken groove for protruding from the window portion of the camera module, a contoured hole is provided on the circular upper cover, the protrusion passes through the contoured hole and exposes the coating area of ​​the camera module.

[0011] Preferably, the window portion of the camera module substrate is formed by punching and the mouth protrudes toward the coating surface.

[0012] Preferably, chromium as a metal combines with oxygen to form an oxide to form a black color.

[0013] The black plating process for the camera module shell proposed in the present invention has the following beneficial effects: the present invention adopts a variety of plating forms, and adjusts the density and internal stress of the film layer by adjusting the concentration of the sputtering gas and the sputtering current, thereby reducing the splitting of the black film and improving the yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below.

[0015] Figure 1 This is a side view of the black film spectrum of this embodiment;

[0016] Figure 2 This is a black film reliability test report diagram of the present invention;

[0017] Figure 3 A schematic diagram of a circular chassis of the jig of the present invention;

[0018] Figure 4 is a schematic diagram of a circular upper cover of the jig of the present invention;

[0019] Figure 5 A schematic diagram of the jig assembly of the present invention;

[0020] Figure 6 It is a schematic diagram of the camera module substrate of the present invention;

[0021] Among them, 1. round bottom plate; 2. round upper cover; 3. square sunken groove; 4. convex block; 5. contoured hole. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0023] Example

[0024] A camera module housing black plating process, comprising the following steps:

[0025] S1: Take the camera module substrate and perform ultrasonic cleaning to keep the surface clean. The camera module substrate in this embodiment is formed by stamping, and the side of the window is also formed inward by stamping, and the mouth is convex toward the coating surface.

[0026] S2: Take the jig, place the camera module on the jig, and press the camera module tightly through the jig cover, leaving the coating position exposed; and preheat the camera module substrate to 80-100°C;

[0027] like Figure 3 , Figure 5 As shown, the fixture includes a circular chassis 1 and a circular upper cover 2, a plurality of positioning posts are arranged between the circular chassis 1 and the circular upper cover 2, a circular groove corresponding to the positioning posts is arranged on the original upper cover, and the positioning posts are inserted into the circular groove to realize the positioning of the upper cover and the chassis to prevent displacement.

[0028] The circular chassis 1 is evenly arranged with a number of square sunken grooves 3, which are used to place the camera module. The square sunken grooves 3 are provided with a protrusion 4, which is used to pass through the window of the camera module. The circular upper cover 2 is provided with a profiling hole 5, through which the protrusion 4 passes. The area of ​​the square hole is larger than the protrusion 4, and the coating area of ​​the camera module is exposed. In addition, since the product mouth is punched out with a protrusion, the inner side of the protrusion is matched with the size of the protrusion 4 and can fit the side wall of the protrusion 4, ensuring that the back of the substrate is coated with a black film during subsequent coating. In addition, the jig can quickly locate the coating area without covering each product separately, which greatly improves efficiency.

[0029] S3: After placing the fixture in the sputtering coating machine, titanium pentoxide, metal chromium, and metal tantalum are respectively taken as cathode targets;

[0030] S4: Vacuum the coating machine to 5*10 -3Pa, first inject argon gas, ionize the argon gas, and first use titanium pentoxide as the cathode target for coating, the coating current is 180mA, after coating titanium pentoxide on the surface of the product, introduce nitrogen gas, at this time the ratio of argon gas to nitrogen is 6:1, then use metal tantalum as the cathode target for coating, and adjust the coating current to 350mA to form a tantalum nitride coating. By adding titanium pentoxide and tantalum nitride coating, the stress between the directly plated black film and the metal material can be effectively reduced, and the current is increased, and the density of the tantalum layer is increased. Then oxygen is introduced again, at this time the ratio of argon gas, nitrogen and oxygen is 6:1:1, and finally the coating is carried out with metal chromium as the cathode target, and the coating is adjusted. The current is 480mA; chromium as a metal combines with oxygen to form an oxide to form black, forming a black plating layer. The coating thickness is 380nm for titanium pentoxide layer, 480nm for chromium nitride layer, and 210nm for tantalum oxide layer, respectively. The coating current, as well as the amount of argon, nitrogen and oxygen, are further increased to adjust the density of chromium oxide to form a denser coating. In addition, due to the prior coating of titanium pentoxide and chromium nitride, the stress between the high-density black coating and the metal is reduced, and splitting will not occur. In addition, the titanium pentoxide coating can increase the strength, and the outside is covered with chromium nitride and tantalum oxide to block ultraviolet rays, solving the problem of titanium pentoxide being easily aged by ultraviolet rays.

[0031] S5: Maintain the pressure for 30 minutes, release the air and take out the material.

[0032] In addition, since the window part of the product is a raised part, gaps are likely to occur during the coating process. The driving device is used to drive the fixture to rotate at a speed of 20r / min to ensure full contact with ions during coating and reduce the risk of missed coating.

[0033] Comparative Example

[0034] The camera module substrate is selected and ultrasonically cleaned to keep the surface clean. The specific conditions of the plasma sputtering coating process are as follows: the temperature is 70℃-80℃, and the absorption film layer 5 is formed by plasma sputtering coating in a high vacuum environment, and is alternately generated by Ti and SiO2. A black film is formed.

[0035] The following tests were performed on the products in the above embodiments and the coatings prepared in the comparative examples:

[0036] Coating spectrophotometry test: Perform spectrophotometry test on the coated product, output the spectrum curve, and judge whether the spectrum meets the specification requirements; the results are detailed in Figure 1 . Anti-reflection specifications

[0037] 420-550nm Rave≤0.5%

[0038] 550-700nm Rave≤0.3%

[0039] Boiling test: Inspection standard: 1. Keep pure water boiling for 1 hour 2. Use 3M CT-18 tape to pull the film 3 times, and the film layer does not fall off or crack.

[0040] High temperature storage: ① Set the temperature of the thermostat to 85℃+2℃; ②) Place the test sample in the thermostat for 240h; ③ The sample is restored under natural conditions for 24h, and then the spectrophotometry, appearance, and film strength are tested.

[0041] Low temperature storage: ① Set the thermostat temperature to -40℃±2℃; ②) Place the test sample in the thermostat for 240h; ③ Let the sample recover for 24h under natural conditions, and then perform spectrometry, appearance, and film strength.

[0042] Constant humidity storage: 1) Set the temperature of the thermostat to 85°C ± 2°C and the relative humidity to 85% ± 2%. 2) Place the test sample in the thermostat for 240 hours. 3) Allow the sample to recover under natural conditions for 24 hours and then perform spectroscopy, appearance, and film strength testing.

[0043] Thermal shock: ①Store in an environment with a cycle of (low temperature -40℃±2℃ (30 minutes) and high temperature 85℃±2℃ (30 minutes)) for 120 times: ②The sample is restored in natural conditions for 24 hours, and the spectrophotometry, appearance and film strength are tested.

[0044] For more details, see Figure 2 .

[0045] In this embodiment, titanium pentoxide is first plated, and then chromium is plated through nitrogen to form chromium nitride, which increases the density of the coating and ensures the bonding of the coating. Titanium pentoxide is used as the bottom layer to reduce the stress between the chromium nitride layer and the metal, preventing excessive stress from causing fragmentation. Finally, a tantalum layer is plated, and a small amount of oxygen is introduced to form a tantalum oxide layer, which further forms a black plating layer, improves the black plating effect, and absorbs ultraviolet rays to reduce the phenomenon of ultraviolet aging caused by combining with titanium pentoxide. Compared with the prior art, the product quality is greatly improved in the direct silicon titanium plating method.

Claims

1. A black plating process for a camera module housing, characterized in that: The following steps are involved: S1: Take the camera module substrate and perform ultrasonic cleaning to keep the surface clean. S2: Take the jig, place the camera module on the jig, and press the camera module tightly through the jig cover, leaving the coating part exposed; and preheat the camera module substrate to 80-100°C; S3: After placing the fixture in the sputtering coating machine, titanium pentoxide, metal chromium, and metal tantalum are respectively taken as cathode targets; S4: Vacuum the coating machine to 5*10 -3 Pa, first inject argon gas, ionize the argon gas, and first use titanium pentoxide as the cathode target for coating, the coating current is 180mA, then introduce nitrogen gas, at this time the ratio of argon gas to nitrogen gas is 6:1, then use metal tantalum as the cathode target for coating, and adjust the coating current to 350mA, introduce oxygen gas again, at this time the ratio of argon gas, nitrogen gas and oxygen gas is 6:1:1, and finally use metal chromium as the cathode target for coating, and adjust the coating current to 480mA; the coating thicknesses are 380nm for titanium pentoxide layer, 480nm for chromium layer, and 210nm for tantalum layer respectively; S5: Maintain the pressure for 30 minutes, release the air and take out the material.

2. The black plating process for the camera module housing according to claim 1, characterized in that: During the coating process, the fixture is driven to rotate at a speed of 20r / min through the driving device.

3. The black plating process for the camera module housing according to claim 1, characterized in that: The fixture includes a circular base and a circular upper cover, a plurality of positioning posts are arranged between the circular base and the circular upper cover, a plurality of square sunken grooves are evenly arranged on the circular base, the square sunken grooves are used to place the camera module, a protrusion is provided on the square sunken groove, which is used to protrude from the window part of the camera module, and a contoured hole is provided on the circular upper cover, the protrusion passes through the contoured hole and exposes the coating area of ​​the camera module.

4. The black plating process for the camera module housing according to claim 1, characterized in that: The window portion of the camera module substrate is formed by punching and the opening is convex toward the coating surface.

5. The black plating process for the camera module housing according to claim 1, characterized in that: Chromium as a metal combines with oxygen to form oxides, which produce black color.

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