Fused deposition manufacturing method of lightweight air dielectric microstrip antenna

Abstract

The invention relates to the technical field of radar electronic antenna feeder subsystem manufacturing, in particular to a fused deposition manufacturing method of a light-weight air dielectric microstrip antenna, which comprises the following steps of: (1) manufacturing a circuit on a copper foil with a carrier through laser processing, and performing surface protection through OSP; (2) fusing and depositing PI (Polyimide) on the circuit pattern, wherein the PI comprises a lower antenna layer, an upper antenna layer and a middle supporting layer; (3) realizing PI foaming manufacturing by using supercritical fluid foaming; and (4) bonding a copper foil on the medium on the top layer without the pattern by using a PI adhesive film, manufacturing a circuit through a laser direct etching method, and performing surface protection through OSP. According to the method, a series of problems that a foam structure is difficult to prepare, a suspended structure is difficult to form and the antenna pattern precision is difficult to guarantee caused by a traditional fused deposition method are effectively solved, meanwhile, the assembly efficiency and the assembly precision are greatly improved, the technological process is simple and rapid, telecommunication indexes are excellent, and stability and reliability are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of radar electronic antenna feed subsystem manufacturing, and in particular to a molten deposition manufacturing method for a lightweight air dielectric microstrip antenna. Background Art

[0002] Air dielectric antennas use an air layer as a dielectric, which reduces the dielectric constant of the antenna medium and broadens the operating bandwidth of microstrip antennas. They are also lightweight and low-cost, making them an important area of current research. Conventional air dielectric antennas use rigid foam to store the air medium and provide structural support and fixation, making them an important component of integrated structural functions. Currently, the rigid foam used is primarily imported PMI foam board, and thin raw materials are unavailable. Mechanical processing is required to produce frames of specified thickness and shape, resulting in limited precision, easy damage, long processing cycles, low material utilization, and high costs. Furthermore, even if the frame is processed into a foam frame, it still needs to be covered with a film antenna on top and bottom, leading to problems such as damage and film wrinkles during assembly, insufficient support strength for local radiating units, and the risk of collapse and deformation, as well as the need for a complex glue bonding material system between the foam structure and the film antenna.

[0003] A homogeneous microstrip antenna with integrated structure and function can be constructed by fused deposition 3D printing. However, the general fused deposition method for producing air dielectric microstrip antennas has the following difficulties:

[0004] (1) The raw material is solid wire, and the nozzle can only heat and melt it to print into a solid solid polymer material, making it difficult to prepare a foam structure;

[0005] (2) To reduce weight, the foam support structure of the air dielectric antenna only retains a small amount of suspended structure, which is difficult to shape;

[0006] (3) The air dielectric microstrip antenna has very high requirements on the precision of the radiating unit, and the antenna pattern layer is difficult to achieve through the fused deposition method.

[0007] Therefore, there is an urgent need to develop a melt deposition manufacturing method for lightweight air dielectric microstrip antennas to solve a series of problems brought about by traditional melt deposition methods, such as the difficulty in preparing foam structures, the difficulty in forming suspended structures, and the difficulty in ensuring the accuracy of antenna graphics. At the same time, it greatly improves assembly efficiency and assembly accuracy, and the process flow is simple and fast, with excellent telecommunications indicators, and stable and reliable.

[0008] In view of the above-mentioned defects, the inventors of the present invention finally obtained the present invention after a long period of research and practice. Summary of the Invention

[0009] The purpose of the present invention is to solve a series of problems brought about by the traditional molten deposition method, such as the difficulty in preparing foam structures, the difficulty in forming suspended structures, and the difficulty in ensuring the accuracy of antenna patterns, and to provide a molten deposition manufacturing method for lightweight air dielectric microstrip antennas.

[0010] In order to achieve the above object, the present invention discloses a method for manufacturing a lightweight air dielectric microstrip antenna by melt deposition, comprising the following steps:

[0011] S1, circuits are fabricated on copper foil with a carrier by laser processing, and surface protection is provided by an organic protective coating (OSP);

[0012] S2, melt-depositing polyimide on the circuit pattern, including the lower and upper antenna layers and the middle support layer;

[0013] S3, using supercritical fluid foaming to achieve polyimide foaming;

[0014] S4, use PI film to bond the copper foil to the medium on the top layer without pattern, make the circuit by laser direct etching method, and use OSP to protect the surface.

[0015] In step S1, the specific process is as follows: a copper foil with a thickness of 8 μm is fixed with the smooth side facing down on a polyimide carrier film, the PI carrier with the copper foil is placed on the table of a laser direct forming device, and the copper foil is processed into an isolated shape of an antenna radiation unit. Due to the adsorption effect of the carrier film, the pattern is retained on the carrier. Outside the effective pattern area, a solid circle pattern with a diameter of Φ1 mm is produced by laser as a zero position to facilitate subsequent positioning and assembly.

[0016] In step S2, the specific process is as follows: the polyimide carrier film is transferred to the table of the fused deposition equipment, and the foamed polyimide medium (TPI) is printed on the copper foil by wire feeding and melting. The printing temperature is 320°C to 340°C, the printing speed is 5mm / s to 20mm / s, and the single layer thickness is 0.02mm to 0.05mm.

[0017] The specific process of printing TPI on copper foil is as follows: first, the lower antenna layer is printed on the copper foil, and the support structure is printed on the lower antenna layer. The support structure is an isolated structure with a solid or hollow shape. Metal sheet support tooling is placed between adjacent support structures. The upper antenna structure is printed on the metal sheet support tooling. After printing, the metal sheet support tooling is removed.

[0018] The size of the lower antenna layer is 500mm×500mm, and the thickness is 0.06mm-0.1mm. The height of the supporting structure is 20mm. The size of the upper antenna layer is 500mm×500mm, and the thickness is 0.06mm-0.1mm.

[0019] In step S3, a foamed structure is prepared using a CO2 supercritical fluid foaming method, and the specific process is as follows: the printed sample is placed in a high-pressure container at 25°C, the container is flushed with low-pressure CO2 for 1 minute to 10 minutes, and immersed in a supercritical CO2 fluid for 10 hours to 15 hours at a pressure of 3MP to 8MPa. After the time is up, the pressure is quickly released, and the CO2-saturated sample is transferred to an oil domain at a temperature of 100°C to 140°C within 1 minute. After the sample is foamed in the oil domain for 10 seconds to 50 seconds, the foamed sample is cooled and shaped in cold water, and then dried at 110 to 125°C for 1 to 3 hours.

[0020] In step S3, the foamed polyimide medium after foaming, including the upper and lower antenna layers and the supporting structure, meets the following requirements: density ≤ 0.6 g / cm 3 , Tg≥350℃, Td≥500℃, dielectric constant≤1.25, dielectric loss≤0.006, compressive strength≥3Mpa.

[0021] In step S3, a 0.025-0.05 mm PI film is used to bond an 8 μm copper foil to the top layer without patterns. The bonding conditions are 150° C. and 15-30 min. The circuit is fabricated by laser direct etching. After fabrication, OSP is used for protection.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. The lightweight air dielectric microstrip antenna prepared in the present invention can be used below the X-band, has excellent electrical performance indicators, and uses the same material to eliminate the risk of sudden changes in dielectric properties of different materials;

[0024] 2. The air dielectric microstrip antenna of the present invention has a size of ≥500mm×500mm and a surface density of ≤1g / cm 3 , the excellent performance of section thickness ≤ 10mm, the weight is reduced by more than 30% compared with traditional process methods, meeting the higher technical requirements of lightweight models;

[0025] 3. The process of the present invention has higher production efficiency. Compared with the original glue solution bonding method, the production time is shortened by more than 75%;

[0026] 4. The lightweight 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 bracket, and dimensional deviation, and significantly improves the assembly yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figures 1 to 3 Schematic diagram of the structure of the air dielectric microstrip antenna in the comparative example, wherein:

[0028] Figure 1is a cross-sectional structural diagram of an air dielectric microstrip antenna in a comparative example;

[0029] Figure 2 It is the PMI foam frame structure diagram in the comparative example;

[0030] Figure 3 Schematic diagram of the collapse and deformation of the air dielectric microstrip antenna in the comparative example when the flexible PCB is insufficiently supported;

[0031] Figures 4 and 5 This is a process flow chart of the air dielectric microstrip antenna in the comparative example, wherein:

[0032] Figure 4 This is a process flow chart of a flexible PCB in a comparative example;

[0033] Figure 5 is a process flow chart of the microstrip antenna in the comparative example;

[0034] Figures 6 and 7 Schematic diagram of the structure of the air dielectric microstrip antenna in Example 1, wherein:

[0035] Figure 6 1 is a cross-sectional structural diagram of the air dielectric microstrip antenna of Example 1;

[0036] Figure 7 Schematic cross-sectional view of the support structure of the air dielectric microstrip antenna of Example 1;

[0037] Figure 8 Schematic diagram of the process flow of Example 1.

[0038] The numbers in the figure represent:

[0039] 1-Upper flexible PCB; 2-Quick-curing adhesive; 3-Lower antenna pattern; 4-Lower flexible PCB; 5-Antenna pattern; 6-Upper antenna pattern; 7-Upper antenna dielectric; 8-Support column; 8-1 to 8-4 are the cross-sectional shapes of different support structures, 8-1 is a hollow honeycomb shape, 8-2 is a solid convex shape, 8-3 is an L shape, and 8-4 is a cross shape. Different cross-sections have different densities and different support effects; 9-Lower antenna dielectric; 10-Antenna pattern; 11-PI film; 12-Antenna pattern. DETAILED DESCRIPTION

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

[0041] Comparative Example

[0042] Comparative example of air dielectric microstrip antenna Figures 1 to 3As shown, it includes a PMI foam frame 5 (with an air cavity inside), an upper flexible PCB 1 (including an antenna pattern 6), a quick-curing glue 2 between the upper and lower flexible PCBs and the PMI foam frame), and a lower flexible PCB 4 (including an antenna pattern 5).

[0043] The assembly process of the comparative example is as follows Figures 4-5 As shown. 2mm PMI foam HF71 is machined to produce Figure 2 The frame shown has dimensions of 500mm x 500mm and a width of 15mm. A 0.1mm thick PI copper-clad laminate with 0.012mm copper foil on both sides is processed through the PCB manufacturing process into a single-sided antenna microstrip board, consisting of an upper flexible PCB and a lower flexible PCB. Instant adhesive 401 is applied to the end surface of the foam bracket. During application, another person manually aligns the upper flexible PCB with the foam bracket, pressing the upper flexible PCB onto the bracket every 50mm to prevent misalignment. After installing the upper flexible PCB, the position of the foam bracket is manually adjusted, and the lower flexible PCB is secured to the foam bracket using the same process to form the subarray module.

[0044] This method inevitably leads to problems with the foam frame breaking and the flexible PCB and bracket offset. After the sub-array module is prepared, the broken parts of the foam frame are reinforced and repaired with instant adhesive 401, and the parts of the flexible PCB that protrude from the frame are 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]

[0048] Example 1

[0049] The structure of Example 1 is as follows Figures 6-7 As shown, Figure 6 As shown, it includes a TPI foam support structure (support column 8, upper antenna medium 7 (including antenna pattern 12 and PI film 11), lower antenna medium 9 (including antenna pattern 10)).

[0050] The assembly process of Example 1 is as follows Figure 7As shown. First, 8um copper foil is attached to the PI carrier film, and the redundant pattern is removed by UV laser from LPKF, leaving only the antenna pattern. The lower layer antenna medium is printed by fused deposition, and the setting conditions are: printing temperature is 335℃, printing speed is 10mm / s, single layer thickness is 0.02mm, total thickness is 0.06mm, and plane size is 500mm×500mm. Then the support structure is printed on the lower layer antenna medium, and the support structure is printed every 50mm. Figure 7 In the combination of 8-2, 8-3, and 8-4, each support structure measures 0.8mm × 0.8mm × 2mm. A metal sheet support fixture is placed between adjacent support structures, upon which the upper antenna structure is printed. The upper dielectric layer measures 500mm × 500mm × 0.06mm. The printed sample is placed in a high-pressure vessel at 25°C, flushed with low-pressure CO2 for 5 minutes, and then immersed in supercritical CO2 fluid at a pressure of 4MPa for 12 hours. After the time is up, the pressure is quickly released. Within 1 minute, the CO2-saturated sample is transferred to an oil bath at 120°C and foamed for 15 seconds. The foamed sample is then cooled in cold water to set the shape, and then dried at 125°C for 2 hours. Using 0.025mm thick PI film, an 8µm thick copper foil is bonded to the unpatterned top layer at 150°C for 30 minutes. The circuit is fabricated using laser direct etching, and after completion, an OSP sealant is applied.

[0051] The final antenna can meet the size ≥500mm×500mm and surface density ≤1g / cm 3 , section thickness ≤ 22mm, and weight is reduced by more than 40% compared with traditional process methods.

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

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

[0054] Serial number Material Type Dielectric constant Base material density thickness 1 Integrated PI antenna 1.2 polyimide <![CDATA[0.5g / cm 3 ]]> 21mm 2 PI film 3.0 polyimide <![CDATA[1.3g / cm 3 ]]> 0.025mm

[0055] Example 2

[0056] The structural dimensions and process path in Example 2 are the same as those in Example 1, except that the TPI support structure is a honeycomb type. The fused deposition setup conditions are: printing temperature of 355°C, printing speed of 7.5mm / s, single layer thickness of 0.05mm, and total thickness of 0.05mm. The upper layer medium dimensions are 500mm×500mm×0.06mm. The printed sample is placed in a high-pressure container at 25°C, flushed with low-pressure CO2 for 10 minutes, and immersed in supercritical CO2 fluid for 15 hours at a pressure of 6MPa. After the time is up, the pressure is quickly released, and the CO2-saturated sample is transferred to an oil field at a temperature of 125°C within 1 minute for foaming for 30 seconds. The foamed sample is then cooled and shaped in cold water. After shaping, it is dried at 110°C for 3 hours. A 0.025mm thick PI film is used to bond an 8um copper foil to the top layer without the pattern. The bonding conditions are 150°C for 30 minutes.

[0057] The final antenna can meet the size ≥500mm×500mm and surface density ≤0.9g / cm 3 , section thickness ≤ 21mm, and weight is reduced by more than 45% compared with traditional process methods.

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

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

[0060] Serial number Material Type Dielectric constant Base material density thickness 1 Integrated PI antenna 1.2 polyimide <![CDATA[0.4g / cm 3 ]]> 21mm 2 PI film 3.0 polyimide <![CDATA[1.3g / cm 3 ]]> 0.025mm

[0061] The above description is merely a preferred embodiment of the present invention and is intended to be illustrative rather than restrictive of the present invention. Those skilled in the art will appreciate that many changes, modifications, and even equivalents may be made to the present invention within the spirit and scope of the claims, all of which fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing a lightweight air dielectric microstrip antenna by melt deposition, characterized in that: The following steps are involved: S1, circuits are made on copper foil with a carrier by laser processing, and the surface is protected by an organic protective coating; S2, melt-depositing polyimide on the circuit pattern, including the lower and upper antenna layers and the middle support layer; S3, using supercritical fluid foaming to achieve polyimide foaming; S4, use PI film to bond the copper foil to the medium on the top layer without pattern, make the circuit by laser direct etching method, and use OSP to protect the surface.

2. The method for manufacturing a lightweight air dielectric microstrip antenna by melt deposition as claimed in claim 1, characterized in that: In step S1, the specific process is as follows: a copper foil with a thickness of 8 μm is fixed with the smooth side facing down on a polyimide carrier film, the PI carrier with the copper foil is placed on the table of a laser direct forming device, and the copper foil is processed into an isolated shape of an antenna radiation unit. Due to the adsorption effect of the carrier film, the pattern is retained on the carrier. Outside the effective pattern area, a solid circle pattern with a diameter of Φ1 mm is produced by laser as a zero position to facilitate subsequent positioning and assembly.

3. The method for manufacturing a lightweight air dielectric microstrip antenna by melt deposition as claimed in claim 1, characterized in that: In step S2, the specific process is as follows: the polyimide carrier film is transferred to the table of the fused deposition equipment, and the foamed polyimide medium is printed on the copper foil by wire feeding and melting. The printing temperature is 320°C to 340°C, the printing speed is 5mm / s to 20mm / s, and the single layer thickness is 0.02mm to 0.05mm.

4. The method for manufacturing a lightweight air dielectric microstrip antenna by melt deposition as claimed in claim 3, characterized in that: The specific process of printing TPI on copper foil is as follows: first, the lower antenna layer is printed on the copper foil, and the support structure is printed on the lower antenna layer. The support structure is an isolated structure with a solid or hollow shape. Metal sheet support tooling is placed between adjacent support structures. The upper antenna structure is printed on the metal sheet support tooling. After printing, the metal sheet support tooling is removed.

5. The method for manufacturing a lightweight air dielectric microstrip antenna by melt deposition as claimed in claim 4, characterized in that: The size of the lower antenna layer is 500mm×500mm, and the thickness is 0.06mm-0.1mm. The height of the supporting structure is 20mm. The size of the upper antenna layer is 500mm×500mm, and the thickness is 0.06mm-0.1mm.

6. The method for manufacturing a lightweight air dielectric microstrip antenna by melt deposition as claimed in claim 1, characterized in that: In step S3, a foamed structure is prepared using a CO2 supercritical fluid foaming method, and the specific process is as follows: the printed sample is placed in a high-pressure container at 25°C, the container is flushed with low-pressure CO2 for 1 minute to 10 minutes, and immersed in a supercritical CO2 fluid for 10 hours to 15 hours at a pressure of 3MP to 8MPa. After the time is up, the pressure is quickly released, and the CO2-saturated sample is transferred to an oil domain at a temperature of 100°C to 140°C within 1 minute. After the sample is foamed in the oil domain for 10 seconds to 50 seconds, the foamed sample is cooled and shaped in cold water, and then dried at 110 to 125°C for 1 to 3 hours.

7. The method for manufacturing a lightweight air dielectric microstrip antenna by melt deposition as claimed in claim 1, characterized in that: In step S3, the properties of the foamed polyimide medium after foaming are as follows: density ≤ 0.6 g / cm 3 , Tg≥350℃, Td≥500℃, dielectric constant≤1.25, dielectric loss≤0.006, compressive strength≥3Mpa.

8. The method for manufacturing a lightweight air dielectric microstrip antenna by melt deposition as claimed in claim 1, characterized in that: In step S3, a 0.025-0.05 mm PI film is used to bond an 8 μm copper foil to the top layer without patterns. The bonding conditions are 150° C. and 15-30 min. The circuit is fabricated by laser direct etching. After fabrication, OSP is used for protection.

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