Light-weight air dielectric microstrip antenna photocuring additive manufacturing method

Abstract

The invention relates to the technical field of radar electronic antenna feeder subsystem manufacturing, in particular to a light-weight air dielectric microstrip antenna photocuring additive manufacturing method which comprises the following steps: (1) preparing a PI aerogel solution; (2) preparing a special-shaped aerogel structure through photocuring 3D printing; (3) solution replacement is matched with supercritical drying to form aerogel; and (4) ink-jet printing is matched with light curing to form the antenna radiation unit. According to the method, a series of problems that a high-thickness and special-shaped suspended structure is difficult to prepare and the antenna pattern precision is difficult to guarantee caused by a traditional fused deposition method are effectively solved, meanwhile, the assembling efficiency and the assembling precision are greatly improved, the technological process is simple and rapid, the telecommunication index is excellent, and stability and reliability are achieved. The finally formed antenna can meet the requirements that the size is larger than or equal to 500mm * 500mm, the surface density is smaller than or equal to 0.9 g / cm < 3 >, the profile thickness is smaller than or equal to 22mm, and the weight is reduced by more than 55% compared with a traditional process method.

Description

Technical Field

[0001] The present invention relates to the technical field of radar electronic antenna feed sub-system manufacturing, and particularly relates to a light-curing additive manufacturing method for a lightweight air dielectric microstrip antenna. Background Art

[0002] Microstrip antennas all contain dielectrics, thus increasing the dielectric loss of the microstrip antennas themselves. If lossless air is used as the dielectric, the gain of the antenna can be increased and the inherent defect of the narrow bandwidth of the microstrip antenna can be improved. Using an air layer as the dielectric can reduce the dielectric constant of the antenna dielectric and broaden the working bandwidth of the microstrip antenna. Therefore, air dielectric antennas have advantages such as good radiation characteristics, simple structure, and easy fabrication.

[0003] [[ID=II]]Generally, foam is used for air dielectric antennas, but the porosity of the foam still has an upper limit. Especially in order to maintain the shape and mechanical strength, some pores need to be sacrificed, resulting in a relatively high dielectric constant. Compared with foam, aerogel has the highest porosity, and the pore size is in the micro-nano scale, and the internal skeleton size is in the micro-nano scale, having the advantages of small pore size, high porosity, and extremely high specific surface area. However, there are the following difficulties in fabricating air dielectric microstrip antennas by general aerogel methods:

[0004] (1) Restricted by the preparation principle, aerogels are usually first prepared into gel films and it is difficult to fabricate thicker structures;

[0005] (2) In order to reduce weight, only a small amount of suspended structure is retained in the support structure of the air dielectric antenna, and it is difficult to use aerogel for shaping;

[0006] (3) The air dielectric microstrip antenna has very high requirements for the accuracy of the radiation unit, and it is difficult to combine the antenna graphic layer with the aerogel dielectric layer.

[0007] Therefore, there is an urgent need to develop a light-curing additive manufacturing method for aerogel air dielectric microstrip antennas to solve a series of problems such as the difficulty in preparing high thickness and special-shaped suspended structures and the difficulty in ensuring the accuracy of antenna graphics brought by traditional aerogel polymerization methods, while greatly improving the assembly efficiency and assembly accuracy, with a simple and fast process flow, excellent electrical performance, and stable and reliable.

[0008] In view of the above defects, the creator of the present invention finally obtained the present invention through long-term research and practice. Summary of the Invention

[0009] The purpose of the present invention is to solve a series of problems such as the difficulty in preparing high thickness and special-shaped suspended structures and the difficulty in ensuring the accuracy of antenna graphics brought by traditional aerogel polymerization methods, and provides a light-curing additive manufacturing method for a lightweight air dielectric microstrip antenna.

[0010] To achieve the above object, the present invention discloses a light-curing additive manufacturing method for a lightweight air-medium microstrip antenna, comprising the following steps:

[0011] S1. Prepare a polyimide aerogel solution;

[0012] S2. Prepare a special-shaped aerogel antenna by light-curing 3D printing;

[0013] S3. Perform solvent replacement and supercritical drying to form an aerogel;

[0014] S4. Perform inkjet printing and light-curing to form an antenna radiation element.

[0015] In the step S1, the specific preparation process of the polyimide aerogel solution is as follows: Dissolve dianhydride and diamine in an organic solvent, add a dehydrating agent, and then add a catalyst. Under the condition of 23°C to 35°C, with a stirring speed of 100 rpm to 500 rpm and a reaction time of 2 h to 4 h, generate an intermediate product polyamic acid through a polymerization reaction, and then obtain a polyimide aerogel solution through chemical imidization.

[0016] The dianhydride is any one or a compound of two or more of pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-oxybisphthalic anhydride (ODPA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 4,4'-oxydianiline (ODA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), hexafluorodiacid anhydride (6FDA), 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (SiDA);

[0017] The diamine is any one or a compound of two or more of 3,3'-dimethylbenzidine (DMBZ), p-phenylenediamine (PDA), 4,4'-oxydianiline (ODA);

[0018] The organic solvent is any one of N-methyl-2-pyrrolidone, tetrahydrofuran, and acetone;

[0019] The dehydrating agent is acetic anhydride, and the catalyst is any one of pyridine, TPO, and photoinitiator 819.

[0020] In the step S1, the viscosity of the polyimide aerogel solution is 0.5 Pa·s to 3 Pa·s.

[0021] In step S2, the shaped aerogel antenna includes a lower antenna layer, a support structure, and an upper antenna layer. The size of the lower antenna layer is 500 mm × 500 mm, and the thickness is 0.06 mm to 0.1 mm. The support structure is an isolated structure, with a shaped solid or hollow shape and a height of 20 mm. The size of the upper antenna layer is 500 mm × 500 mm, and the thickness is 0.06 mm to 0.1 mm.

[0022] The antenna medium in the lower antenna layer and the upper antenna layer is fabricated using digital light processing technology. The optical power of the digital light processing is 1 to 4 mW / cm 2 , the printing time is 5 to 15 s, and the thickness of each printed layer is 0.02 mm to 0.05 mm.

[0023] In step S3, the specific process is as follows: Immerse the shaped aerogel antenna medium in a solvent replacement liquid, replace the replacement liquid 3 to 5 times, with an interval of 10 h to 20 h each time, and then use the CO2 supercritical fluid method to prepare the aerogel.

[0024] The specific process of the CO2 supercritical fluid method is as follows: Place the printed sample in a high-pressure vessel at 35 to 70 °C, rinse the vessel with low-pressure CO2 for 1 min to 10 min, soak it in supercritical CO2 fluid for 10 h to 15 h, with a pressure of 5 MP to 10 Mpa. After the time is up, quickly depressurize, transfer the sample saturated with CO2 to an oil bath at a temperature of 100 °C to 140 °C within 1 min. After the sample is impregnated in the oil bath for 10 s to 50 s, cool and shape the foamed sample in cold water, and dry it at 110 to 125 °C for 1 to 3 h after shaping.

[0025] In step S3, the performance of the completed polyimide aerogel dielectric layer meets the following requirements: density ≤ 0.5 g / cm 3 , Tg ≥ 350 °C, Td ≥ 500 °C, dielectric constant ≤ 1.25, dielectric loss ≤ 0.006, and compressive strength ≥ 3 Mpa.

[0026] In step S4, the specific process is as follows: Fabricate the circuit through ultraviolet-assisted direct writing technology, and use OSP for protection after fabrication; the conductive ink used in inkjet is a mixture of PAA-HEMA photosensitive resin oligomer and nanosilver wires, and the crosslinking agent is TMPTA; the precision of the fabricated antenna pattern is 0.2 ± 0.02 mm.

[0027] The beneficial effects of the present invention compared with the prior art are as follows:

[0028] 1. The aerogel air dielectric microstrip antenna prepared in the present invention can be used below the X band, with excellent electrical performance indicators, and eliminates the risk of dielectric property mutation of different materials by using the same material;

[0029] 2. The aerogel air dielectric microstrip antenna in the present invention achieves excellent performance with dimensions ≥ 500 mm × 500 mm, areal density ≤ 0.9 g / cm 3 , cross-sectional thickness ≤ 22 mm, reducing the weight by more than 45% compared to the traditional process method, meeting the higher technical requirements for lightweight of the model product;

[0030] 3. The production efficiency of the process method of the present invention is higher, and the production time is shortened by more than 75%;

[0031] 4. The aerogel air dielectric microstrip antenna of the present invention eliminates the failure problems of the original antenna such as local deformation, easy damage of the foam support, and size deviation, and the assembly yield is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figures 1 to 2 FIG. is a schematic structural diagram of the air dielectric microstrip antenna in the comparative example, where:

[0033] Figure 1 is the cross-sectional structure diagram of the comparative example;

[0034] Figure 2 is the PMI foam frame structure diagram;

[0035] Figure 3 is the process flow diagram of the air dielectric microstrip antenna in the comparative example;

[0036] Figure 4 is the schematic structural diagram of the aerogel air dielectric microstrip antenna in Example 1;

[0037] Figure 5 is the process flow diagram of the aerogel air dielectric microstrip antenna in Example 1

[0038] The numbers in the figure represent:

[0039] 1 - upper flexible antenna dielectric; 2 - rapid curing adhesive; 3 - lower antenna pattern; 4 - lower flexible antenna dielectric; 5 - support column; 6 - upper antenna pattern; 7 - aerogel PI structure layer; 8 - upper and lower antenna patterns. DETAILED DESCRIPTION OF THE INVENTION

[0040] The above and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0041] Comparative Example

[0042] The comparative example air dielectric microstrip antenna is as Figure 1 shown, and includes a PMI foam frame 5 (with an air cavity inside), an upper flexible antenna dielectric 1, an upper antenna pattern 6, a rapid curing adhesive 2 between the upper and lower flexible antennas and the PMI foam frame, a lower flexible antenna dielectric 4, and a lower antenna pattern 5.

[0043] The assembly process of the comparative example is as Figure 2 shown. The 2-mm PMI foam HF51 is machined to produce a frame with a size of 500 mm × 500 mm and a frame width of 15 mm. A PI copper-clad laminate with a thickness of 0.1 mm and a copper foil thickness of 0.012 mm on both sides is processed into a single-sided antenna microstrip board through the PCB process, including an upper flexible PCB and a lower flexible PCB. Instant adhesive 401 is coated on the end face of the foam bracket. During the coating process, another person manually aligns the upper flexible PCB with the foam bracket. Every 50 mm of coating, the upper flexible PCB is pressed onto the bracket to prevent misalignment. After installing the upper flexible PCB, the position of the foam bracket is manually corrected, and the lower flexible PCB is fixed to the foam bracket in the same process to form a sub-array module.

[0044] This method inevitably has problems such as foam frame fracture and offset between the flexible PCB and the bracket. After the sub-array module is prepared, the broken part of the foam frame is reinforced and repaired with instant adhesive 401, and the part of the flexible PCB that extends beyond the frame is manually removed.

[0045] The performance comparison of different materials is shown in Table 1 below.

[0046] Table 1 Materials used in the comparative example air dielectric microstrip antenna

[0047] Serial number Material type Dielectric constant Matrix material Density Thickness 1 PMI foam 1.2 Polymethacrylimide (PMI) <![CDATA[0.51g / cm 3 > 21 mm 2 PI copper clad laminate 3.5 Polyimide <![CDATA[1.4g / cm 3 > 0.1 mm 3 Quick-drying glue 401 3.0 Ethyl cyanoacrylate 1.1 g / cm3 0.07 mm

[0048] Example 1

[0049] The structure of Example 1 is as Figure 3 shown, including an aerogel PI structure layer 7 and a pattern 8.

[0050] The preparation process of Example 1 is as Figure 4 shown. First, a solution is prepared. The molar ratio of the raw materials except the solvent is ODA:BPDA:NMP:TAB:aa:Py = 1:1.03:60:0.022:8.24:8.24 mol, and the viscosity of the prepared aerogel solution is 0.5 Pa·s. The optical power of the DLP used to fabricate the antenna dielectric by the DLP technology is 2 mW / cm 2, the printing time is 7 s, and the thickness of each printed layer is 0.02 mm. The finally formed special-shaped structure is as follows: the lower antenna layer, with a size of 500 mm × 500 mm and a thickness of 0.06 mm; the support structure is in a solid special shape, with a height of 20 mm and a spacing of 50 mm; the upper antenna layer has a size of 500 mm × 500 mm and a thickness of 0.06 mm. The printed sample is placed in a high-pressure container at 30 °C, and the container is rinsed with low-pressure CO2 for 10 min, soaked in supercritical CO2 fluid for 12 h, and the pressure is 6 MPa. After the time is up, the pressure is quickly released, and the sample saturated with CO2 is transferred to an oil bath at 120 °C within 1 min for foaming for 15 s. Then, the foamed sample is cooled and shaped in cold water, and after shaping, it is dried at 125 °C for 2 h. The silver-based circuit is fabricated by the UV-DIW method, and after fabrication, OSP is used for protection.

[0051] The finally formed antenna can meet the requirements of size ≥500 mm × 500 mm, surface density ≤0.5 g / cm 3 , sectional thickness ≤22 mm, and the weight is reduced by more than 55% compared with the traditional process method.

[0052] The performance comparison of different materials is shown in Table 2 below.

[0053] Table 2 Materials used in the air dielectric microstrip antenna of Example 1

[0054] Serial number Material type Dielectric constant Matrix material Density Thickness 1 Integrated PI antenna 1.2 Polyimide <![CDATA[0.4g / cm 3 > 21 mm

[0055] Example 2

[0056] The structural dimensions and process routes of Example 2 are the same as those of Example 1, but the support structure is a hollow honeycomb type. The optical power of the DLP used to fabricate the antenna dielectric by the DLP technology is 4 mW / cm 2 , the printing time is 12 s, and the thickness of each printed layer is 0.05 mm. The finally formed special-shaped structure is as follows: the lower antenna layer, with a size of 500 mm × 500 mm and a thickness of 0.05 mm; the support structure is in a hollow honeycomb type, with a height of 20 mm and a spacing of 50 mm; the upper antenna layer has a size of 500 mm × 500 mm and a thickness of 0.05 mm. The printed sample is placed in a high-pressure container at 40 °C, and the container is rinsed with low-pressure CO2 for 12 min, soaked in supercritical CO2 fluid for 15 h, and the pressure is 10 MPa. After the time is up, the pressure is quickly released, and the sample saturated with CO2 is transferred to an oil bath at 130 °C within 1 min for foaming for 10 s. Then, the foamed sample is cooled and shaped in cold water, and after shaping, it is dried at 110 °C for 5 h. The silver-based circuit is fabricated by the UV-DIW method, and after fabrication, OSP is used for protection.

[0057] The finally formed antenna can meet the requirements that the size is ≥500mm×500mm, the areal density is ≤0.4g / cm 3 , the sectional thickness is ≤21mm, and the weight is reduced by more than 60% compared with the traditional process method.

[0058] The performance comparison of different materials is shown in Table 3 below.

[0059] Table 3 Materials used in the air dielectric microstrip antenna of Example 2

[0060] Serial number Material type Dielectric constant Matrix material Density Thickness 1 Integrated PI antenna 1.2 Polyimide <![CDATA[0.3g / cm 3 > 21 mm

[0061] The above are only the preferred embodiments of the present invention, which are illustrative rather than restrictive to the present invention. Those skilled in the art understand that many changes, modifications or even equivalents can be made within the spirit and scope defined by the claims of the present invention, but all will fall within the protection scope of the present invention.

Claims

1. A light-curing additive manufacturing method for a lightweight air dielectric microstrip antenna, characterized in that It includes the following steps: S1. Prepare a polyimide aerogel solution; S2. Prepare a shaped aerogel antenna by photocuring 3D printing; S3. Perform solvent replacement and supercritical drying to form an aerogel; S4. Perform inkjet printing and photocuring to form an antenna radiation element.

2. The light-curing additive manufacturing method of a lightweight air dielectric microstrip antenna according to claim 1, characterized in that In the step S1, the specific preparation process of the polyimide aerogel solution is as follows: Dissolve dianhydride and diamine in an organic solvent, add a dehydrating agent, and then add a catalyst. Under the conditions of 23°C to 35°C, with a stirring speed of 100 rpm to 500 rpm and a reaction time of 2 h to 4 h, generate an intermediate product polyamic acid through a polymerization reaction, and then obtain the polyimide aerogel solution through chemical imidization.

3. The light-curing additive manufacturing method of a lightweight air medium microstrip antenna according to claim 2, characterized in that, The dianhydride is any one or a compound of two or more of pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-oxydiphthalic anhydride (ODPA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 4,4'-oxydianiline (ODA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), hexafluorodiacid anhydride (6FDA), 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (SiDA); The diamine is any one or a compound of two or more of 3,3'-dimethylbenzidine (DMBZ), p-phenylenediamine (PDA), 4,4'-oxydianiline (ODA); The organic solvent is any one of N-methyl-2-pyrrolidone, tetrahydrofuran, and acetone; The dehydrating agent is acetic anhydride, and the catalyst is any one of pyridine, TPO, and photoinitiator 819.

4. The light-curing additive manufacturing method of a lightweight air dielectric microstrip antenna as described in claim 1, characterized in that In the step S1, the viscosity of the polyimide aerogel solution is 0.5 Pa·s to 3 Pa·s.

5. The light-curing additive manufacturing method of a lightweight air dielectric microstrip antenna according to claim 1, characterized in that In the step S2, the shaped aerogel antenna includes a lower antenna layer, a support structure, and an upper antenna layer. The size of the lower antenna layer is 500 mm × 500 mm, and the thickness is 0.06 mm to 0.1 mm. The support structure is an isolated structure, with a shaped solid or hollow shape and a height of 20 mm. The size of the upper antenna layer is 500 mm × 500 mm, and the thickness is 0.06 mm to 0.1 mm.

6. The light-curing additive manufacturing method of a lightweight air medium microstrip antenna according to claim 5, characterized in that, The antenna medium in the lower antenna layer and the upper antenna layer is fabricated using digital light processing technology, and the optical power of the digital light processing is 1 - 4 mW / cm 2 , the printing time is 5 - 15 s, and the thickness of each printed layer is 0.02 mm - 0.05 mm.

7. The light-curing additive manufacturing method of a lightweight air dielectric microstrip antenna as claimed in claim 1, characterized in that In the step S3, the specific process is as follows: Immerse the shaped aerogel antenna medium in a solvent replacement liquid, replace the replacement liquid 3 to 5 times, with an interval of 10 h to 20 h each time, and then use the CO2 supercritical fluid method to prepare the aerogel.

8. The light-curing additive manufacturing method of a lightweight air dielectric microstrip antenna according to claim 7, characterized in that The specific process of the CO2 supercritical fluid method is as follows: Place the printed sample in a high-pressure container at 35 to 70°C, rinse the container with low-pressure CO2 for 1 min to 10 min, soak it in supercritical CO2 fluid for 10 h to 15 h, with a pressure of 5 MPa to 10 MPa. After the time, quickly depressurize, transfer the sample saturated with CO2 to an oil bath at 100°C to 140°C within 1 min. After the sample is impregnated in the oil bath for 10 s to 50 s, cool and shape the foamed sample in cold water. After shaping, dry it at 110 to 125°C for 1 to 3 h.

9. The light-curing additive manufacturing method of a lightweight air dielectric microstrip antenna according to claim 1, characterized in that, In the step S3, the performance of the completed dielectric layer meets the following requirements: density ≤ 0.5 g / cm 3 , Tg ≥ 350 °C, Td ≥ 500 °C, dielectric constant ≤ 1.25, dielectric loss ≤ 0.006, and compressive strength ≥ 3 Mpa.

10. The light-curing additive manufacturing method of a lightweight air dielectric microstrip antenna as described in claim 1, characterized in that, In the step S4, the specific process is as follows: A circuit is fabricated by ultraviolet-assisted direct writing technology, and after fabrication, OSP is used for protection; the conductive ink used in inkjet printing is a mixture of PAA-HEMA photosensitive resin oligomer and nanosilver wires, and the crosslinking agent is TMPTA; the graphic accuracy of the fabricated antenna pattern is 0.2 ± 0.02 mm.

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