High-hardness HUD free-form surface mirror and magnetron sputtering coating preparation method thereof

Abstract

The invention relates to a high-hardness HUD free-form surface mirror and a magnetron sputtering coating preparation method thereof, a plastic free-form surface mirror is sequentially provided with a combined film layer and a superhard optical thin film layer group, and the superhard optical thin film layer group comprises an Al film layer, a first SiO2 film layer, an Nb2O5 film layer and a second SiO2 film layer which are sequentially arranged on the combined film layer. The method comprises the following steps: putting a high polymer material HUD free-form surface mirror into a vacuum multi-cavity magnetic control coating machine, and introducing inert gas; the first layer is plated with a third SiO2 film layer by adopting a CVD (Chemical Vapor Deposition) method and is combined with the high polymer material HUD free-form surface mirror to form the third SiO2 film layer; and plating the superhard optical thin film layer group by using a PVD (Physical Vapor Deposition) method, and sequentially forming an Al film layer, a first SiO2 film layer, an Nb2O5 film layer and a second SiO2 film layer on the third SiO2 film layer. By optimizing the film system design and the preparation process, the HUD free-form surface mirror achieves high hardness and meets the requirement for high-temperature storage.

Description

Technical Field

[0001] This invention relates to the field of optical product manufacturing, and in particular to a high-hardness HUD freeform surface mirror and its magnetron sputtering coating preparation method. Background Technology

[0002] The freeform surface mirror of a head-up display (HUD) is a key component of an automotive head-up display system. Its function is to reflect the image from the instrument panel into the driver's field of vision, allowing the driver to view vehicle information without looking down. Currently, most freeform surface mirrors for HUDs use glass or polymer substrates and are coated using technologies such as magnetron sputtering.

[0003] While glass-based HUD mirrors offer superior optical performance, they are heavy, fragile, and expensive to manufacture. Conversely, polymer-based HUD mirrors, though lightweight and inexpensive, suffer from low hardness, poor scratch resistance, and insufficient film-substrate adhesion.

[0004] Therefore, in order to reduce the cost of HUD while meeting the functional requirements of HUD, it is necessary to develop a process for depositing high-hardness reflective films on freeform surfaces of polymer HUDs. Summary of the Invention

[0005] The purpose of this invention is to provide a high-hardness HUD freeform surface mirror and its magnetron sputtering coating preparation method, which can achieve high hardness and meet the requirements for high-temperature storage by optimizing the film system design and preparation process.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-hardness HUD freeform surface mirror, comprising a plastic freeform surface mirror, wherein a bonding film layer and an ultra-hard optical thin film layer group are sequentially disposed on the plastic freeform surface mirror, and the ultra-hard optical thin film layer group comprises an Al film layer, a first SiO2 film layer, an Nb2O5 film layer and a second SiO2 film layer sequentially disposed on the bonding film layer.

[0007] Furthermore, the bonding film layer is a third SiO2 film layer.

[0008] Furthermore, the Al film layer has a thickness of 85-95 nm; the first SiO2 film layer has a thickness of 65-75 nm; the Nb2O5 film layer has a thickness of 40-45 nm; and the second SiO2 film layer has a thickness of 25-35 nm.

[0009] Furthermore, the thickness of the third SiO2 film is 15-25 nm.

[0010] Furthermore, the bonding film layer is bonded to the plastic freeform mirror to form a bonding layer for buffering the differences between the ultra-hard optical thin film layer group and the plastic freeform mirror.

[0011] Furthermore, the refractive index of the Nb2O5 film is 2.25-2.4, the refractive indices of the first SiO2 film, the second SiO2 film, and the third SiO2 film are 1.43-1.47, and the refractive index of the Al film is 4.25-7.05.

[0012] A method for preparing a high-hardness HUD freeform surface mirror by magnetron sputtering coating, the method comprising the following steps:

[0013] Step S1: Place the polymer material HUD freeform mirror into a vacuum multi-cavity magnetron coating machine and evacuate it to 1.5*E-3Pa;

[0014] Step S2: The first layer is a third SiO2 film layer deposited by PECVD chemical vapor deposition. PECVD uses plasma to dissociate silicone oil molecules into highly active free radicals, ions, etc., which are then combined with polymer material HUD freeform mirror to form the third SiO2 film layer.

[0015] Step S3: Deposit an ultrahard optical thin film layer group using the PVD physical vapor deposition method, and sequentially form an Al film layer, a first SiO2 film layer, an Nb2O5 film layer, and a second SiO2 film layer on the third SiO2 film layer.

[0016] Furthermore, the deposition parameters for step S2 are as follows: the film material is HDMS---C6H. 18 OSi2, film material gas flow rate is 15-25 sccm, coating time is 45-55s, RF power is 10-20kW, and Ar gas flow rate is 25-35 sccm.

[0017] Further, in step S3, the deposition parameters for forming the Al film are: Al target as the film material, deposition time of 30-40 seconds, RF power of 15-25 kW, and Ar gas flow rate of 95-105 sccm; the deposition parameters for forming the first SiO2 film are: Si target as the film material, deposition time of 145-155 seconds, RF power of 5-15 kW, Ar gas flow rate of 95-105 sccm, and O2 gas flow rate of 95-105 sccm; when forming the N... The deposition parameters for the b2O5 film are as follows: the film material is an Nb target, the deposition time is 125-135 s, the RF power is 10-20 kW, the Ar gas flow rate is 95-105 sccm, and the O2 gas flow rate is 95-105 sccm. The deposition parameters for the second SiO2 film are as follows: the film material is a Si target, the deposition time is 65-75 s, the RF power is 5-15 kW, the Ar gas flow rate is 95-105 sccm, and the O2 gas flow rate is 95-105 sccm.

[0018] The beneficial effects of this invention are: to reduce the cost of HUDs while meeting their functional requirements, a high-hardness polymer material freeform surface HUD mirror and its preparation method are provided.

[0019] 1. By optimizing the film system design and preparation process, a polymer material HUD freeform surface mirror can be obtained that meets the anti-friction test of optical thin film. The high-hardness polymer material HUD freeform surface mirror of the present invention can achieve the following hardness test: wet a degreased cotton ball or a white cotton soft cloth with anhydrous ethanol, and then wipe the same position on the coating surface back and forth with a pressure of 0.5 kg and a speed of 1 round trip once per second for 20 times. The product surface has no scratches.

[0020] 2. The high-hardness polymer material HUD freeform mirror described in this invention can meet the requirements for high-temperature storage:

[0021] After setting the temperature to 105℃ and storing for 1000 hours, the membrane did not peel off or crack after 100 cross-section testing.

[0022] 3. The high-hardness polymer material HUD freeform mirror described in this invention can meet the requirements of thermal shock resistance:

[0023] -40℃, 30min; 95℃, 30min (30S, 500 times), after ring testing, no film peeling or cracking.

[0024] 4. The HUD device of this invention ensures product performance, has a simple and practical structure, and is easy to implement. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the HUD freeform surface mirror of the present invention.

[0026] Among them: 1. HUD freeform mirror, 2. third SiO2 film layer, 3. Al film layer, 4. first SiO2 film layer, 5. Nb2O5 film layer, 6. second SiO2 film layer. Detailed Implementation

[0027] The invention will now be further described with reference to the accompanying drawings.

[0028] Please see Figure 1 This invention provides an embodiment: a high-hardness HUD freeform surface mirror, comprising a plastic freeform surface mirror, on which a bonding film layer and an ultra-hard optical thin film layer group are sequentially disposed. The ultra-hard optical thin film layer group includes an Al film layer 3, a first SiO2 film layer 4, an Nb2O5 film layer 5, and a second SiO2 film layer 6 sequentially disposed on the bonding film layer. The plastic freeform surface mirror has five film layers, one of which is a bonding film layer, and the other four are ultra-hard optical thin film layer groups. The film system structure is as follows: Figure 1 As shown.

[0029] Please see Figure 1 The present invention provides another embodiment: the bonding film layer is a third SiO2 film layer 2.

[0030] Please see Figure 1 The present invention provides another embodiment: the Al film layer 3 has a thickness of 85-95 nm; the first SiO2 film layer 4 has a thickness of 65-75 nm; the Nb2O5 film layer 5 has a thickness of 40-45 nm; and the second SiO2 film layer 6 has a thickness of 25-35 nm. Preferably, the thickness of the Al film layer 3 is 90 nm, the thickness of the first SiO2 film layer 4 is 70 nm, the thickness of the Nb2O5 film layer 5 is 45 nm, and the thickness of the second SiO2 film layer 6 is 30 nm.

[0031] Please see Figure 1 The present invention provides another embodiment: the thickness of the third SiO2 film layer 2 is 15-25 nm. Preferably, the thickness of the third SiO2 film layer 2 is 20 nm.

[0032] Please see Figure 1 The present invention provides another embodiment: the bonding film layer is bonded to the plastic freeform mirror to form a bonding layer for buffering the differences between the ultra-hard optical thin film layer group and the plastic freeform mirror.

[0033] Please see Figure 1 The present invention provides another embodiment: the refractive index of the Nb2O5 film layer 5 is 2.25-2.4, the refractive indices of the first SiO2 film layer 4, the second SiO2 film layer 6 and the third SiO2 film layer 2 are 1.43-1.47, and the refractive index of the Al film layer 3 is 4.25-7.05.

[0034] Please see Figure 1 The present invention provides an embodiment: a method for preparing a high-hardness HUD freeform surface mirror by magnetron sputtering coating, comprising the following steps:

[0035] Step S1: Place the polymer material HUD freeform mirror 1 into a vacuum multi-cavity magnetron coating machine and introduce inert gas;

[0036] Step S2: The first layer is a third SiO2 film layer 2 deposited by CVD chemical vapor deposition, which is combined with the polymer material HUD freeform mirror 1 to form the third SiO2 film layer 2. By using CVD SiO2 deposition as the bonding layer between the plastic freeform mirror and the bonding film layer, the bonding layer is used as a buffer layer to alleviate the difference between the two and enhance the adhesion of the film layer on the plastic part.

[0037] Step S3: A superhard optical thin film layer assembly is deposited using PVD (Physical Vapor Deposition). An Al film layer 3, a first SiO2 film layer 4, a Nb2O5 film layer 5, and a second SiO2 film layer 6 are sequentially formed on the third SiO2 film layer 2. Using PVD to deposit metallic Al and high-refractive-index niobium pentoxide (Nb2O5) and low-refractive-index silicon dioxide (SiO2) functional layers, the PVD-deposited film layer has high density and can form a superhard optical thin film. The superhard optical thin film layer assembly includes a metallic Al layer, high-refractive-index niobium pentoxide (Nb2O5), and low-refractive-index silicon dioxide (SiO2). At an incident angle of 8 degrees, the average reflectivity in the visible light (400-700nm) band reaches 94%. The working principle of PVD deposition is to introduce an inert gas (such as argon, Ar) and apply a high-voltage electric field (hundreds of volts) between the cathode (target) and anode (substrate holder), causing the argon gas to ionize and form plasma (Ar). + Ar with positive charge + In magnetron sputtering, the target surface is bombarded under an electric field, sputtering target atoms or molecules through momentum transfer. The sputtered target atoms / molecules fly towards the substrate (such as glass or metal) as neutral particles. These particles adsorb, diffuse, and condense on the substrate surface, gradually forming a uniform thin film. Polymer materials are prone to deformation or degradation at high temperatures. During magnetron sputtering, the high-energy particles generated by the bombardment of the target can raise the surface temperature of the substrate, potentially leading to softening, deformation, or performance degradation of the polymer material. To control the temperature during the coating process, a multi-cavity coating device is used, with each layer of film coated using a separate coating cavity, effectively controlling the coating temperature. This invention, through optimized film system design and preparation process, can obtain a polymer material HUD freeform surface mirror 1 that meets the optical thin film abrasion resistance test: severity level 01, 50 cycles of abrasion with degreased cotton gauze, the inspection method is as specified in GB T26332.4.

[0038] Please see Figure 1 The present invention provides another embodiment: the deposition parameters for step S2 are: the film material is HDMS---C6H 18 OSi2, film material gas flow rate is 15-25 sccm, coating time is 45-55s, RF power is 10-20kW, and Ar gas flow rate is 25-35 sccm.

[0039] Please see Figure 1The present invention provides another embodiment: In step S3, the deposition parameters when forming the Al film layer 3 are: the film material is an Al target, the deposition time is 30-40 s, the radio frequency power is 15-25 kW, and the Ar gas flow rate is 95-105 sccm; the deposition parameters when forming the first SiO2 film layer 4 are: the film material is a Si target, the deposition time is 145-155 s, the radio frequency power is 5-15 kW, the Ar gas flow rate is 95-105 sccm, and the O2 gas flow rate is 95-105 sccm. The deposition parameters for forming the Nb2O5 film layer 5 are as follows: the film material is an Nb target, the deposition time is 125-135 s, the RF power is 10-20 kW, the Ar gas flow rate is 95-105 sccm, and the O2 gas flow rate is 95-105 sccm. The deposition parameters for forming the second SiO2 film layer 6 are as follows: the film material is a Si target, the deposition time is 65-75 s, the RF power is 5-15 kW, the Ar gas flow rate is 95-105 sccm, and the O2 gas flow rate is 95-105 sccm. Specific Implementation Example 1:

[0041] The polymer material HUD freeform mirror 1 was placed into a vacuum multi-cavity magnetron coating machine and evacuated to 1.5*E-3Pa;

[0042] The first layer uses PECVD chemical vapor deposition to deposit the third SiO2 film layer 2 (deposited according to the parameters in Table 1), which is combined with the polymer material HUD freeform mirror 1 to form the third SiO2 film layer 2. PECVD uses plasma (glow discharge) to dissociate silicone oil molecules into highly active free radicals, ions, etc., which undergo chemical reactions on the substrate surface and are deposited into a film.

[0043] Table 1. Deposition parameters for the third SiO2 film layer

[0044] Membrane materials Membrane material air volume (sccm) Time (s) Radio frequency power (kW) Ar(sccm) <![CDATA[HDMS---C6H 18 OSi2]]> 20 50 1.5 30

[0045] An ultrahard optical thin film layer group (as shown in Table 2 below) was deposited using the PVD physical vapor deposition method. An Al film layer 3, a first SiO2 film layer 4, a Nb2O5 film layer 5, and a second SiO2 film layer 6 were sequentially formed on the third SiO2 film layer 2. The PVD deposition principle is as follows: an inert gas (such as argon, Ar) is introduced, and a high-voltage electric field (hundreds of volts) is applied between the cathode (target material) and the anode (substrate holder), causing the argon gas to ionize and form plasma (Ar). + Ar with positive charge + The target surface is sputtered by bombarding it with an electric field, and the target atoms or molecules are sputtered out through momentum transfer. The sputtered target atoms / molecules fly towards the substrate (such as glass, metal, etc.) as neutral particles. The particles are adsorbed, diffused and condensed on the substrate surface, gradually forming a uniform thin film.

[0046] Table 2. Deposition parameters for coating ultrahard optical thin film layers

[0047] membrane Membrane materials Time (s) Radio frequency power (kW) Ar(sccm) <![CDATA[O2(sccm)]]> AL film Al target 35 20 100 0 <![CDATA[The first SiO2 film layer]]> Si target 150 10 100 100 <![CDATA[Nb2O5 film layer]]> Nb target 130 15 100 100 <![CDATA[Second SiO2 film layer]]> Si target 70 10 100 100

[0048] The present invention has the following working principle: By optimizing the film system design and preparation process, the present invention can obtain a polymer material HUD freeform surface mirror that meets the requirements of optical thin film. SiO2 is used as the bonding layer of plastic freeform surface mirror and ultra-hard optical thin film layer group. The bonding layer is used as a buffer layer to alleviate the difference between the two and enhance the adhesion of the film layer on the plastic part. The functional layers are metal Al and high refractive index niobium pentoxide (Nb2O5) and low refractive index silicon dioxide (SiO2). The PVD coating film has high density and can form an ultra-hard optical thin film.

[0049] The above description is only a preferred embodiment of the present invention and should not be construed as a limitation of this application. All equivalent changes and modifications made in accordance with the scope of the patent application of the present invention should be covered by the present invention.

Claims

1. A high-hardness HUD freeform surface mirror, comprising a plastic freeform surface mirror, characterized in that: The plastic freeform mirror is sequentially provided with a bonding film layer and an ultrahard optical thin film layer group. The ultrahard optical thin film layer group includes an Al film layer, a first SiO2 film layer, an Nb2O5 film layer, and a second SiO2 film layer sequentially disposed on the bonding film layer.

2. The high-hardness HUD freeform surface mirror according to claim 1, characterized in that: The bonding film is a third SiO2 film.

3. The high-hardness HUD freeform surface mirror according to claim 1, characterized in that: The Al film has a thickness of 85-95 nm; the first SiO2 film has a thickness of 65-75 nm; the Nb2O5 film has a thickness of 40-45 nm; and the second SiO2 film has a thickness of 25-35 nm.

4. The high-hardness HUD freeform surface mirror according to claim 2, characterized in that: The thickness of the third SiO2 film is 15-25 nm.

5. A high-hardness HUD freeform surface mirror according to claim 1, characterized in that: The bonding film layer is combined with the plastic freeform mirror to form a bonding layer that buffers the differences between the ultra-hard optical thin film layer group and the plastic freeform mirror. The refractive index of the Nb2O5 film is 2.25-2.4, the refractive indices of the first SiO2 film, the second SiO2 film, and the third SiO2 film are 1.43-1.47, and the refractive index of the Al film is 4.25-7.

05.

6. A method for preparing a magnetron sputtering coating for a high-hardness HUD freeform surface mirror as described in claim 1, characterized in that: The process includes the following steps: Step S1: Place the polymer material HUD freeform mirror into a vacuum multi-cavity magnetron coating machine and evacuate it to 1.5*E-3Pa; Step S2: The first layer is a third SiO2 film layer deposited by PECVD chemical vapor deposition. PECVD uses plasma to dissociate silicone oil molecules into highly active free radicals, ions, etc., which are then combined with polymer material HUD freeform mirror to form the third SiO2 film layer. Step S3: Deposit an ultrahard optical thin film layer group using the PVD physical vapor deposition method, and sequentially form an Al film layer, a first SiO2 film layer, an Nb2O5 film layer, and a second SiO2 film layer on the third SiO2 film layer.

7. The method for preparing a high-hardness HUD freeform surface mirror by magnetron sputtering coating according to claim 6, characterized in that: The deposition parameters for step S2 are as follows: the film material is HDMS---C6H. 18 OSi2, film material gas flow rate is 15-25 sccm, coating time is 45-55s, RF power is 10-20kW, and Ar gas flow rate is 25-35 sccm.

8. The method for preparing a high-hardness HUD freeform surface mirror by magnetron sputtering coating according to claim 6, characterized in that: In step S3, the deposition parameters for forming the Al film are as follows: the film material is an Al target, the deposition time is 30-40 seconds, the RF power is 15-25 kW, and the Ar gas flow rate is 95-105 sccm; the deposition parameters for forming the first SiO2 film are as follows: the film material is a Si target, the deposition time is 145-155 seconds, the RF power is 5-15 kW, the Ar gas flow rate is 95-105 sccm, and the O2 gas flow rate is 95-105 sccm; when forming Nb2... The deposition parameters for the O5 film are as follows: the film material is an Nb target, the deposition time is 125-135 s, the RF power is 10-20 kW, the Ar gas flow rate is 95-105 sccm, and the O2 gas flow rate is 95-105 sccm. The deposition parameters for the second SiO2 film are as follows: the film material is a Si target, the deposition time is 65-75 s, the RF power is 5-15 kW, the Ar gas flow rate is 95-105 sccm, and the O2 gas flow rate is 95-105 sccm.

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