Aluminum etching antenna manufacturing method

Abstract

The invention discloses a method for manufacturing an aluminum etching antenna. The method comprises the following steps of: 1, designing a reinforcing rib; step 2, etching step by step; step 3, gradient curing treatment; step 4, coating a hydrophobic coating; and step 5, binding and packaging the chip. Through accurate process parameter control and structural innovation, high-frequency performance and production efficiency are taken into consideration while the packaging reliability is improved, the core contradiction that mechanical strength, signal loss and cost efficiency cannot be achieved at the same time in the prior art is solved, and the packaging structure is particularly suitable for high-frequency and high-reliability scenes such as Internet of Things RFID and 5G communication.

Description

Technical Field

[0001] The invention belongs to the technical field of antenna manufacturing, and in particular relates to a method for manufacturing an aluminum etching antenna. Background Art

[0002] In advanced packaging processes, the aluminum etched antenna is a key component for signal transmission. The interface bonding strength between the antenna and the packaging substrate / molding compound directly affects the shear performance of the package. Insufficient shear force can cause the chip to delaminate or crack under harsh working conditions such as temperature cycling and mechanical vibration, causing signal distortion and even device failure. Existing technology defect analysis: Insufficient interface bonding strength:

[0003] Traditional aluminum etched antennas use a single metal layer structure (such as pure aluminum or aluminum-copper alloy). The aluminum surface easily forms a dense oxide layer and has a low surface roughness (Ra is usually <0.3μm), resulting in a weak mechanical interlocking effect with organic substrates (epoxy resin, polyimide, etc.). Experiments have shown that the package shear force at the chip position of this structure is generally less than 50kgf / cm 2 , which cannot meet the long-term reliability requirements of high-frequency chips.

[0004] Interface bonding can be improved by increasing the thickness of the adhesive or introducing a coupling agent, but these methods introduce additional process complexity and produce parasitic capacitance interference on high-frequency signal transmission. Summary of the Invention

[0005] The present invention provides a method for manufacturing an aluminum etched antenna that systematically improves the package shear force through aluminum antenna structure innovation and process collaborative optimization without sacrificing electrical performance. The method is used to solve the technical problem of reliability of aluminum etched antennas in chip packaging caused by insufficient interface bonding strength, process defects and thermal mismatch.

[0006] The present invention provides a method for manufacturing an aluminum etching antenna, comprising:

[0007] Step 1: Rib design:

[0008] In the gravure printing roller of the aluminum antenna, grid-shaped or striped reinforcement ribs are prepared in the chip bonding area. The line density of the reinforcement ribs is 133 lines / inch to 250 lines / inch, and the side length of a single grid is 0.005mm-0.15mm.

[0009] The grid and rib area of the printing gravure roller have a height difference of 0.01mm-0.05mm. The difference in ink inventory during printing increases the surface roughness Ra of the aluminum layer to 0.3μm-0.5μm.

[0010] Step 2: Etching step by step:

[0011] The first etching stage: using a phosphoric acid-based etching solution with a concentration of 20wt%-30wt% and a temperature of 40°C-60°C for 5-15 minutes to reveal the grid-like or striped reinforcement ribs in the chip bonding area;

[0012] Second etching stage: using a phosphoric acid-based etching solution with a concentration of 5wt%-10wt% and a temperature of 25°C-35°C, micro-etching the sidewalls of the aluminum layer in the binding area for 1 minute-5 minutes until the sidewall roughness Ra is ≥0.5μm;

[0013] Step 3: Gradient aging treatment:

[0014] The first stage: aging at 50℃-60℃ for 12 hours to 24 hours to release the thermal and mechanical stress during etching and oxidation;

[0015] The second stage: aging at 60-90°C for 12-24 hours to increase the porosity of the aluminum surface oxide layer to 10%-30% (thickness 50-200nm);

[0016] The relative humidity of the curing environment is maintained at 30%-50%, and the heating rate is 1℃ / min-5℃ / min;

[0017] Step 4: Hydrophobic coating:

[0018] Apply a hydrophobic coating to the surface of the aluminum foil with a thickness of 5nm-50nm and a contact angle of ≥120°;

[0019] Step 5: Chip bonding and packaging:

[0020] Conductive adhesive is applied to the bonding area, wherein the conductive adhesive contains nickel-gold alloy conductive particles with a particle size of 3 μm to 10 μm and a volume filling rate of 5% to 15%. The adhesive is infiltrated into the pores of the reinforcement grid by vacuum assistance, wherein the vacuum degree is -50 kPa to -80 kPa;

[0021] After aligning the chip with the binding area, hot pressing and curing are performed for 10 seconds to 30 seconds at a pressure of 0.2MPa-0.8MPa and a temperature of 150℃-180℃ to form a mechanical-chemical double interlocking structure with a shear force of ≥50MPa.

[0022] Furthermore, the hydrophobic coating is a fluorosilane hydrophobic coating, which includes heptadecafluorodecyltrimethoxysilane, TEOS crosslinker and perfluorohexane diluent, wherein the mass proportion of heptadecafluorodecyltrimethoxysilane is 80%-95%, the mass proportion of the TEOS crosslinker is 4%-10%, and the mass proportion of the perfluorohexane diluent is 1%-10%.

[0023] Furthermore, the hydrophobic coating is a perfluoropolyether hydrophobic coating, which includes perfluoropolyether, silica nanoparticles and perfluoropolyether oil solvent, wherein the mass proportion of perfluoropolyether is 70%-90%, the mass proportion of silica nanoparticles is 3%-8%, and the mass proportion of perfluoropolyether oil is 2%-27%.

[0024] Furthermore, in step 2, the etching time ratio between the first etching stage and the second etching stage is 3:1-5:1, and the sidewall roughness Ra of the second etching is 0.5 μm-1.2 μm.

[0025] Furthermore, in step 4, the hydrophobic coating is sprayed with a spraying process, a spraying pressure of 0.2 MPa-0.5 MPa, a curing temperature of 80° C.-120° C., and a curing time of 5 minutes-10 minutes.

[0026] Furthermore, in step 5, the hot pressing curing process includes a pre-pressing stage and a final pressing stage:

[0027] Pre-pressing stage: pressure 0.4MPa-0.6MPa, temperature 80℃-100℃, duration 5s-10s;

[0028] Final pressure stage: pressure 0.6MPa-0.8MPa, temperature 150℃-180℃, duration 5 seconds-20 seconds.

[0029] The aluminum etched antenna manufacturing method of this application first designs grid-shaped / striped reinforcement ribs in the chip binding area of the aluminum antenna printing plate roller to improve the overall structural rigidity. Then, through chemical etching or plasma treatment, the aluminum surface roughness (Ra) reaches 0.5-2.0μm, enhancing the mechanical anchoring effect. Through the coordinated optimization of surface roughening, step-by-step etching and material matching, a shear force of ≥100kgf / cm is achieved. 2 And the signal loss is reduced by 10-15%. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0031] Figure 1 A schematic diagram of a single printing gravure roller antenna provided by one embodiment of the present invention;

[0032] Figure 2 A schematic cross-sectional view of a binding area provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] Aluminum etching antenna manufacturing method achieves a balance between mechanical bonding strength and high-frequency performance through structure-process collaborative optimization.

[0035] Method: Grid-shaped or striped reinforcement ribs are prepared in the chip bonding area of the printed gravure roller of the aluminum antenna, with a line density of 133-250 LPI (lines / inch) and a single grid side length of 0.05-0.15 mm (such as Figure 1 As shown in the figure, the difference in ink inventory during printing increases the surface roughness of the aluminum layer, increasing the effective bonding area and dispersing the shear stress.

[0036] The etching process is divided into two stages: the first etching stage uses a phosphoric acid-based etching solution with a concentration of 20-30wt% and a temperature of 40-60°C to etch for 5-15 minutes to reveal the reinforcing ribs in the binding area; the second etching stage uses a phosphoric acid-based etching solution with a concentration of 5-10wt% and a temperature of 25-35°C to micro-etch the sidewall for 1-5 minutes to make the roughness Ra ≥ 0.5μm.

[0037] The etched aluminum antenna is subjected to gradient temperature aging in a controlled temperature and humidity environment (humidity 30-50%), from 50°C to 90°C at a rate of 1-5°C / min for a total of 24-48 hours to eliminate residual stress and form a dense-porous oxide layer (thickness 50-200nm, porosity 10-30%).

[0038] The aluminum foil surface is then coated with a hydrophobic coating of fluorosilane or perfluoropolyether (PFPE) with a thickness of 5-50 nm and a contact angle ≥120°. The preferred spray coating method is a spray pressure of 0.2-0.5 MPa, a curing temperature of 80-120°C, and a curing time of 5-10 minutes. After a humidity test (85°C / 85% RH, 1000 hours), the shear force attenuation rate is <10% (compared to >30% with conventional processes).

[0039] The anisotropic conductive adhesive (ACF) is coated on the bonding area using a flip-chip device. The colloid contains nickel-gold alloy conductive particles with a particle size of 3-10 μm (volume filling rate of 5-15%). The colloid is infiltrated into the pores of the reinforcement grid (such as Figure 2 shown).

[0040] After the chip is aligned with the binding area, it is hot-pressed and cured for 10-30 seconds at a pressure of 0.2-0.8 MPa and a temperature of 150-180°C to form a double interlocking structure of mechanical anchoring (particle-pore interlocking) and chemical bonding (oxide layer-resin reaction), and the shear force is increased to ≥30KG.

[0041] Among them, the thickness of the aluminum foil is preferably 0.009-0.05mm;

[0042] Among them, the hydrophobic coating is preferably silane or perfluoropolyether (PFPE) with a thickness of 5-50nm;

[0043] This invention, through precise control of process parameters (etching solution concentration, curing temperature and humidity, and conductive adhesive filling rate) and structural innovation, improves packaging reliability while taking into account high-frequency performance and production efficiency, solving the core contradiction of "mechanical strength-signal loss-cost efficiency" in the existing technology, and is particularly suitable for high-frequency and high-reliability scenarios such as Internet of Things RFID and 5G communications.

[0044] In a specific embodiment, Figure 1 As shown, a single antenna pattern (100) is designed in the printing gravure roll of the aluminum antenna, wherein the chip binding position is area 110 (shown in the enlarged view).

[0045] like Figure 1 As shown, the width of the A1 grid curve in the (100) position is 0.005mm-0.015mm, the groove depth is 0.005mm-0.01mm, and the A2 reinforcement line density is 133-250LPI.

[0046] like Figure 1 As shown, when the gravure roller prints the antenna, the height difference between the grid and the ribs leads to inconsistent ink inventory, and the surface roughness is increased to Ra = 0.8-1.5μm.

[0047] Following the above, the antenna is etched in stages after printing: a. The first etching stage uses a phosphoric acid-based etchant at a concentration of 20-30% and a temperature of 40-60°C for 5-15 minutes to expose the grid / striped reinforcement ribs in the bonding area; b. The second etching stage uses a phosphoric acid-based etchant at a concentration of 5-10% and a temperature of 25-35°C for micro-etching for 1-5 minutes to reduce the sidewall roughness Ra to 0.5-1.2 μm.

[0048] As mentioned above, the time ratio between the first and second etching stages is 3:1-5:1, and the second etching sidewall roughness Ra is controlled within the range of 0.5-1.2 μm.

[0049] Continuing with the above, the etched aluminum antenna is placed in a controlled temperature and humidity environment and aged for 24-48 hours at a gradient temperature ramp from 50°C to 90°C. The first stage is aging at 50-60°C for 12-24 hours to release thermal and mechanical stresses. The second stage is aging at 60-90°C for 12-24 hours to achieve a porosity of 10-30% in the oxide layer.

[0050] Following the above, the aging program temperature rise rate is 1-5°C / min, and the relative humidity of the environment is maintained at 30-50%.

[0051] like Figure 2 As shown, the surface of the aluminum foil is coated with a hydrophobic coating of fluorosilane or perfluoropolyether (PFPE) as S2, with a thickness of 5-50 nm and a contact angle ≥120°; the spraying process is completed with a spraying pressure of 0.2-0.5 MPa, a curing temperature of 80-120°C, and a time of 5-10 minutes.

[0052] like Figure 2 As shown, the IC chip bonding area is coated with S1 anisotropic conductive adhesive (ACF), which contains nickel-gold alloy conductive particles with a particle size of 3-10μm (volume filling rate 5-15%) and is infiltrated into the A1 reinforcement grid pores through vacuum assistance; the antenna 100 layer structure is S3 aluminum foil and S4 PET substrate.

[0053] like Figure 2 As shown, after the IC chip pins are aligned with the antenna binding area, they are hot-pressed and cured for 10-30 seconds at a pressure of 0.2-0.8 MPa and a temperature of 150-180°C: the pre-pressing stage is 0.4-0.6 MPa and 80-100°C for 5-10 seconds; the final pressing stage is 0.6-0.8 MPa and 150-180°C for 5-20 seconds. The chip pins penetrate the coating and form a mechanical-chemical double interlocking structure with the aluminum foil surface.

[0054] Example 1: High-frequency RFID tag packaging

[0055] parameter:

[0056] The linear density of the reinforcement is 200LPI, and the thickness of the aluminum foil is 0.02mm;

[0057] Hydrophobic coating: PFPE (molecular weight 3000 g / mol), thickness 20 nm, spray coating process (0.3 MPa, 100 °C / 8 min);

[0058] Test results:

[0059] Shear force: 52.3MPa (48.1MPa after wet heat test, attenuation rate 8.0%);

[0060] Signal loss: 0.42dB@915MHz (compared to 0.40dB without coating);

[0061] Comparative Example (without hydrophobic coating):

[0062] Shear force attenuation rate>30%, signal loss 0.60dB@915MHz.

[0063] Specifically, the hydrophobic coating is a fluorosilane hydrophobic coating, which includes heptadecafluorodecyltrimethoxysilane, TEOS crosslinker and perfluorohexane diluent, wherein the mass proportion of heptadecafluorodecyltrimethoxysilane is 80%-95%, the mass proportion of TEOS crosslinker is 4%-10%, and the mass proportion of perfluorohexane diluent is 1%-10%.

[0064] Example 2

[0065] formula:

[0066] Heptadecafluorodecyltrimethoxysilane: 95%

[0067] TEOS crosslinker: 4%

[0068] Perfluorohexane diluent: 1%

[0069] performance:

[0070] Contact angle: 140°

[0071] Dielectric constant @28GHz: 2.4

[0072] Shear force attenuation rate after wet heat aging: 10%.

[0073] Example 3

[0074] formula:

[0075] Heptadecafluorodecyltrimethoxysilane: 80%

[0076] TEOS crosslinker: 10%

[0077] Perfluorohexane diluent: 10%

[0078] performance:

[0079] Contact angle: 130°

[0080] Dielectric constant @28GHz: 2.2

[0081] Shear force attenuation rate after wet heat aging: 9%.

[0082] Example 4

[0083] formula:

[0084] Heptadecafluorodecyltrimethoxysilane: 90%

[0085] TEOS crosslinker: 8%

[0086] Perfluorohexane diluent: 2%

[0087] performance:

[0088] Contact angle: 130°

[0089] Dielectric constant @28GHz: 2.2

[0090] Shear force attenuation rate after wet heat aging: 9%.

[0091] Furthermore, the hydrophobic coating is a perfluoropolyether hydrophobic coating, which includes perfluoropolyether, silica nanoparticles and perfluoropolyether oil solvent, wherein the mass proportion of perfluoropolyether is 70%-90%, the mass proportion of silica nanoparticles is 3%-8%, and the mass proportion of perfluoropolyether oil is 2%-22%.

[0092] Example 5

[0093] formula:

[0094] PFPE (Mw=3500, terminal hydroxyl group): 90%

[0095] Silica nanoparticles (20 nm): 3%

[0096] PFPE oil solvent: 2%

[0097] performance:

[0098] Contact angle: 145°

[0099] Dielectric constant @40GHz: 1.9

[0100] Salt spray resistance test (5% NaCl, 500h): No corrosion.

[0101] Example 6

[0102] formula:

[0103] PFPE (Mw=3500, terminal hydroxyl group): 70%

[0104] Silica nanoparticles (20nm): 8%

[0105] PFPE oil solvent: 22%

[0106] performance:

[0107] Contact angle: 150°

[0108] Dielectric constant @40GHz: 2.0

[0109] Salt spray resistance test (5% NaCl, 500h): No corrosion.

[0110] Example 7

[0111] formula:

[0112] PFPE (Mw=3500, terminal hydroxyl group): 85%

[0113] Silica nanoparticles (20 nm): 5%

[0114] PFPE oil solvent: 5%

[0115] performance:

[0116] Contact angle: 152° (super hydrophobic)

[0117] Dielectric constant @40GHz: 2.1

[0118] Salt spray resistance test (5% NaCl, 500h): No corrosion.

[0119] Comparative Example (Traditional Silicone Oil Coating)

[0120] Formula: Polydimethylsiloxane (PDMS)

[0121] defect:

[0122] Contact angle: 110° (less than)

[0123] Dielectric constant @10GHz: 2.8 (high loss at high frequencies)

[0124] Moisture heat attenuation rate: 25%.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for manufacturing an aluminum etching antenna, characterized in that: include: Step 1: Rib design: In the gravure printing roller of the aluminum antenna, grid-shaped or striped reinforcement ribs are prepared in the chip bonding area. The line density of the reinforcement ribs is 133 lines / inch to 250 lines / inch, and the side length of a single grid is 0.005mm-0.15mm. The grid and rib area of the printing gravure roller have a height difference of 0.01mm-0.05mm. The difference in ink inventory during printing increases the surface roughness Ra of the aluminum layer to 0.3μm-0.5μm. Step 2: Etching step by step: The first etching stage: using a phosphoric acid-based etching solution with a concentration of 20wt%-30wt% and a temperature of 40°C-60°C for 5-15 minutes to reveal the grid-like or striped reinforcement ribs in the chip bonding area; Second etching stage: using a phosphoric acid-based etching solution with a concentration of 5wt%-10wt% and a temperature of 25°C-35°C, micro-etching the sidewalls of the aluminum layer in the binding area for 1 minute-5 minutes until the sidewall roughness Ra is ≥0.5μm; Step 3: Gradient aging treatment: The first stage: aging at 50℃-60℃ for 12 hours to 24 hours to release the thermal and mechanical stress during etching and oxidation; The second stage: aging at 60-90°C for 12-24 hours to increase the porosity of the aluminum surface oxide layer to 10%-30% (thickness 50-200nm); The relative humidity of the curing environment is maintained at 30%-50%, and the heating rate is 1℃ / min-5℃ / min; Step 4: Hydrophobic coating: Apply a hydrophobic coating to the surface of the aluminum foil with a thickness of 5nm-50nm and a contact angle of ≥120°; Step 5: Chip bonding and packaging: Conductive adhesive is applied to the bonding area, wherein the conductive adhesive contains nickel-gold alloy conductive particles with a particle size of 3 μm to 10 μm and a volume filling rate of 5% to 15%. The adhesive is infiltrated into the pores of the reinforcement grid by vacuum assistance, wherein the vacuum degree is -50 kPa to -80 kPa; After aligning the chip with the binding area, hot pressing and curing are performed for 10 seconds to 30 seconds at a pressure of 0.2MPa-0.8MPa and a temperature of 150℃-180℃ to form a mechanical-chemical double interlocking structure with a shear force of ≥50MPa.

2. The method for manufacturing an aluminum etching antenna according to claim 1, wherein: The hydrophobic coating is a fluorosilane hydrophobic coating, which includes heptadecafluorodecyltrimethoxysilane, a TEOS crosslinker, and a perfluorohexane diluent, wherein the mass proportion of the heptadecafluorodecyltrimethoxysilane is 80%-95%, the mass proportion of the TEOS crosslinker is 4%-10%, and the mass proportion of the perfluorohexane diluent is 1%-10%.

3. The method for manufacturing an aluminum etching antenna according to claim 1, wherein: The hydrophobic coating is a perfluoropolyether hydrophobic coating, which includes perfluoropolyether, silica nanoparticles and perfluoropolyether oil solvent, wherein the mass proportion of perfluoropolyether is 70%-90%, the mass proportion of silica nanoparticles is 3%-8%, and the mass proportion of perfluoropolyether oil is 2%-22%.

4. The method for manufacturing an aluminum etching antenna according to claim 1, wherein: In step 2, the etching time ratio between the first etching stage and the second etching stage is 3:1-5:1, and the sidewall roughness Ra of the second etching is 0.5 μm-1.2 μm.

5. The method for manufacturing an aluminum etching antenna according to claim 1, wherein: In step 4, the hydrophobic coating is sprayed with a spraying process, a spraying pressure of 0.2 MPa-0.5 MPa, a curing temperature of 80° C.-120° C., and a curing time of 5 minutes-10 minutes.

6. The method for manufacturing an aluminum etching antenna according to claim 1, wherein: In step 5, the hot pressing curing process includes the pre-pressing stage and the final pressing stage: Pre-pressing stage: pressure 0.4MPa-0.6MPa, temperature 80℃-100℃, duration 5s-10s; Final pressure stage: pressure 0.6MPa-0.8MPa, temperature 150℃-180℃, duration 5 seconds-20 seconds.

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