A semi-solid formed aluminum alloy optical module housing and a manufacturing process thereof

Abstract

The application discloses a kind of semi-solid forming aluminum alloy light module tube shell and preparation process thereof, belong to optical communication device packaging technical field.The shell is integrated hollow frame structure, by semi-solid rheological die casting one integral forming, base material is Al-Mg-Si series aluminum alloy, its component includes by mass percentage:Si 0.4~0.8%, Mg 0.6~1.1%, Cu 0.15~0.3%, the balance is Al.Tube shell forming wall thickness is 0.6mm~1.2mm, internal organization is uniform spherical isometric crystal and no pore shrinkage.The preparation process includes aluminum alloy smelting, gas cooling stirring preparation semi-solid slurry, rheological die casting laminar filling, T6 solid solution aging heat treatment, precision finishing and surface plating treatment.The application breaks through the bottleneck that traditional die casting cannot T6 heat treatment, and the shell has high thermal conductivity, high strength, high airtightness and excellent electromagnetic shielding performance, and can adapt to up to 12.8T high-speed optical module, silicon optical chip and CPO co-encapsulation optical assembly packaging requirements.

Description

Technical Field

[0001] This invention belongs to the field of optical communication device packaging technology, and particularly relates to a semi-solid molded aluminum alloy optical module shell and its manufacturing process. Background Technology

[0002] With the rapid iteration of cloud computing, data centers, and high-speed computing networks, optical modules are developing towards high power, high-frequency millimeter-wave, miniaturization, thin-walled design, and high-tightness vacuum packaging. Transmission rates are continuously evolving from 100G, 400G, and 800G to 1.6T, 3.2T, and even 12.8T. Next-generation optoelectronic devices such as silicon photonics chips and CPO co-packaged optical components place extremely stringent requirements on the density, thermal conductivity, dimensional accuracy, and electromagnetic shielding performance of aluminum housings. Optical module housings not only need excellent mechanical properties and heat dissipation capabilities but must also meet the airtightness requirements of advanced packaging processes such as vacuum brazing.

[0003] Currently, there are three main technical routes for the fabrication of aluminum alloy optical module shells, but all of them have obvious drawbacks: Traditional liquid high-pressure die casting process: The molten metal flows at high speed and turbulently to fill the mold, and the gas in the mold cavity cannot be discharged. There are a lot of pores and shrinkage defects inside the shell, which makes it impossible to carry out T6 solution aging heat treatment. The thermal conductivity, strength and airtightness are greatly reduced. Micropores cause electromagnetic leakage during high-frequency signal transmission, and vacuum brazing cannot be used to seal them, making it difficult to meet the packaging requirements of high-end silicon photonics and CPO devices. Thin-walled structure molding is prone to material shortage and deformation, resulting in low batch yield.

[0004] The process of machining a solid aluminum alloy using CNC machining involves milling and hollowing out a solid aluminum block, resulting in a material utilization rate of less than 40%. The process involves numerous steps and a long production cycle. The processing costs for complex internal cavities, micro heat dissipation fins, and multiple sets of positioning bosses are extremely high. Furthermore, the product is heavy, which is not conducive to lightweight integration of equipment.

[0005] Forging process: High mold investment cost, slow forming cycle, small light window mounting steps, sealing flanges, and small threaded columns cannot be formed in one step, and the subsequent CNC machining allowance is huge, making large-scale mass production uneconomical.

[0006] In summary, none of the existing three processes can simultaneously achieve the comprehensive goals of one-piece molding of ultra-thin complex structures, high density and defect-free properties, T6 heat treatment for strengthening, high airtightness, and low-cost mass production. Therefore, there is an urgent need to develop a new type of aluminum alloy optical module shell and its molding process to overcome the bottlenecks of existing technologies. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing aluminum alloy optical module shell manufacturing technologies—traditional liquid high-pressure die casting cannot avoid porosity and shrinkage and cannot undergo T6 heat treatment; single-piece CNC machining has low material utilization and high cost; and forging is difficult to mass-produce. This invention provides a semi-solid-formed aluminum alloy optical module shell and its manufacturing process. Through alloy composition optimization, synergistic combination of semi-solid rheo-die casting and T6 heat treatment, it aims to simultaneously achieve one-time integral forming of ultra-thin complex structures, high-density and defect-free internal structure, T6 solution-aging heat treatment for strengthening, high thermal conductivity and high airtightness, and low-cost mass production, meeting the comprehensive performance requirements of 100G and above high-speed optical modules, silicon photonics chips, and CPO co-packaged optical components for the packaging shell.

[0008] To achieve the above objectives, the present invention provides a semi-solid molded aluminum alloy optical module shell, characterized in that the shell is an integrated hollow frame structure, integrally molded in one piece by a semi-solid rheo-die casting process, without the need for segmented welding, and is used to encapsulate optical modules with a transmission rate of not less than 100G; preferably, the shell is used to encapsulate high-speed optical modules with a transmission rate of 400G to 12.8T.

[0009] Furthermore, the substrate of the tube shell is a low-silicon, high-thermal-conductivity Al-Mg-Si aluminum alloy. The alloy composition by mass percentage includes: Si 0.4%~0.8%, Mg 0.6%~1.1%, Cu 0.15%~0.3%, with the balance being Al. The total impurity content of the alloy composition is ≤0.1%.

[0010] Furthermore, the structure of the casing includes a base plate, four side walls, a top sealing edge, built-in heat dissipation microribs, a fiber optic window mounting platform, PCB positioning threaded posts, RF pin slots, and shielding ribs.

[0011] Furthermore, the shell has a wall thickness of 0.6mm to 1.2mm, and its internal microstructure consists of uniform spherical equiaxed crystals with a grain size ≤45μm, free from coarse dendrites, continuous pores, and shrinkage defects.

[0012] Furthermore, after T6 solution aging heat treatment, the tube shell has a thermal conductivity ≥145W / (m·K), tensile strength ≥330MPa, yield strength ≥210MPa, and vacuum leak detection rate ≤1×10⁻⁶. -9 Pa·m 3 / s, and the electromagnetic shielding effectiveness in the 26-40GHz millimeter wave band is ≥60dB.

[0013] Furthermore, the sealing plane, the light window positioning hole, and the threaded hole of the tube shell are precision machined surfaces, while the remaining forming surfaces are die-cast blank surfaces, and the material utilization rate of the tube shell is ≥85%.

[0014] Furthermore, the surface of the tube shell is sequentially provided with a conductive passivation layer, a thin nickel layer, and a palladium plating layer.

[0015] This invention also provides a manufacturing process for a semi-solid-formed aluminum alloy optical module housing, comprising the following steps: S1. Aluminum alloy smelting: aluminum ingots and intermediate alloys are added according to the mass ratio of Si 0.4%~0.8%, Mg 0.6%~1.1%, Cu 0.15%~0.3%, with the balance being Al. The mixture is melted and held at a temperature above the liquidus line. After refining, degassing, and slag removal, impurities and free hydrogen in the melt are removed to obtain aluminum alloy melt. S2. Semi-solid slurry preparation: The aluminum alloy melt is transported to an air-cooled stirring slurry preparation device, and the dendritic structure is broken by low-temperature shearing and stirring. The solid phase ratio of the slurry is controlled at 25%~35% to obtain a spherical crystal uniform semi-solid slurry. The slurry temperature is maintained at 590℃~610℃. S3. Rheological die casting: The semi-solid slurry is slowly and steadily conveyed to the die casting mold cavity and filled using a laminar flow filling method, without splashing or turbulent air entrapment; after holding the cavity pressure for 12~18s, the mold is opened and the blank is removed. S4. The blank is cooled and deburred. It is naturally air-cooled to room temperature, and then vibratory grinding is used to remove the flash and burrs without damaging the shell forming surface. S5.T6 heat treatment involves placing the blank at 530℃ for solution treatment and heat preservation, followed by rapid water quenching, and then aging treatment at 170℃ to eliminate casting internal stress and simultaneously improve shell strength, thermal conductivity and dimensional stability. After heat treatment, the overall deformation of the shell is ≤0.03mm. S6. Precision machining: Micro-CNC milling and drilling / tapping are performed on the sealing edge plane, through hole, and threaded column inner hole of the heat-treated tube blank. S7. Surface plating treatment: The above-mentioned tube shell is subjected to degreasing and cleaning, conductive passivation, electroless nickel plating, palladium gold plating, and drying to obtain the finished optical module aluminum tube shell.

[0016] Furthermore, in step S2, the stirring speed is 600~900 r / min, and the air cooling volume is stably controlled to ensure uniform spheroidization of the crystals.

[0017] Furthermore, the preheating temperature of the die-casting mold in S3 is 220℃~260℃, which reduces the thermal shock of the slurry and extends the service life of the mold.

[0018] This invention breaks with the traditional technical bias that "high silicon content is necessary to ensure fluidity" in die casting, instead using a low-silicon Al-Mg-Si alloy as the base material. The low silicon content reduces the volume fraction of the Si phase in the alloy, significantly improving the thermal conductivity potential of the as-cast matrix and laying the foundation for achieving a high thermal conductivity of ≥145 W / (m·K) after subsequent T6 heat treatment. Simultaneously, the appropriate addition of Mg and Cu forms Mg2Si and Al2Cu reinforcing phases, which, after T6 solution aging treatment, achieve precipitation strengthening, ensuring that the shell possesses both high strength and high thermal conductivity.

[0019] In terms of molding process, this invention employs air-cooled stirring slurry preparation technology. Forced shearing and stirring are applied during the transformation of the alloy melt from a liquid to a semi-solid state, breaking up and spheroidizing primary dendrites to obtain a spherical semi-solid slurry with a solid fraction of 25%~35% and a temperature of 590℃~610℃. Compared to liquid metal, the semi-solid slurry itself carries approximately 30% solid crystal nuclei, making it less prone to splashing and turbulence during flow. This invention delivers the slurry to the mold cavity at a low speed and smoothly, filling it using a laminar flow filling method, fundamentally avoiding the air entrapment problem caused by the high-speed turbulent filling of traditional liquid die casting. Simultaneously, laminar flow filling allows sufficient time for gas in the cavity to escape from the venting channels, ensuring high density of the shell and eliminating continuous porosity and shrinkage defects inside.

[0020] The highly dense blank structure allows the shell to withstand a 530℃ high-temperature solution treatment without blistering or cracking, a breakthrough that traditional die castings cannot achieve. The T6 solution treatment and aging process effectively dissolves the non-equilibrium eutectic phases in the as-cast structure, allowing solute atoms such as Mg and Cu to fully dissolve into the aluminum matrix. Subsequent rapid water quenching and aging at 170℃ result in uniformly dispersed nanoscale precipitates, producing a significant precipitation strengthening effect. Furthermore, the high-temperature solution treatment eliminates micro-segregation in the as-cast structure, resulting in purer grain boundaries and reduced scattering of thermally conductive electrons and phonons, thereby simultaneously improving thermal conductivity.

[0021] Furthermore, the integrated molding structure design integrates the base plate, side walls, sealing edges, heat dissipation microribs, light window mounting platform, positioning posts, RF grooves, and shielding ribs into a single die-casting process, reducing subsequent machining and assembly steps. Only the sealing surface, positioning holes, and threaded holes have a small machining allowance, while the remaining molding surfaces are directly usable, achieving near-net-shape molding.

[0022] The integrated hollow frame structure of the optical module housing described in this invention has the following design for each functional component: The base plate is used to support the PCB board and optoelectronic chip of the optical module. Its flatness is controlled within 0.02mm after precision machining to ensure chip mounting accuracy.

[0023] The four side walls and the base plate together form a hollow cavity, providing installation space and electromagnetic shielding for the internal components of the optical module.

[0024] The top sealing edge is a sealing flange structure on the upper end face of the pipe shell. After precision machining, the surface roughness Ra≤0.8μm is used for vacuum brazing or laser sealing with metal or ceramic cover plates to achieve airtight sealing.

[0025] The built-in heat dissipation microribs are miniature heat dissipation fin structures located on the inner surface of the base plate. The ribs are 1.0~2.0mm high, 0.4~0.6mm thick, and 0.8~1.5mm apart, used to increase the heat dissipation area and improve heat dissipation efficiency. This microrib structure is formed in one piece in semi-solid rheological die casting, requiring no subsequent processing.

[0026] The fiber optic window mounting platform is a fiber optic interface mounting surface located at a specific position on the side wall. It is used to install ceramic optical windows or fiber optic adapters to enable the internal and external transmission of optical signals.

[0027] PCB positioning threaded posts are multiple positioning bosses and internal threaded holes located on the base plate, used for precise positioning and fixed installation of PCB boards.

[0028] The RF pin slot is a pin lead-out slot structure located on the side wall, used for the exit and insulating installation of RF signal pins.

[0029] The shielding ribs are isolation rib structures located inside the cavity, used to divide the cavity into different shielding areas and reduce electromagnetic interference between high-frequency signals.

[0030] All the above functional structures are integrally formed in one piece during the semi-solid rheo-die casting process, without the need for subsequent welding or assembly, thus ensuring the structural integrity and dimensional consistency of the shell.

[0031] In summary, the innovative points of this invention are: 1. Innovative Alloy Composition: Breaking away from the conventional practice of using high-silicon aluminum alloys for semi-solid die-cast communication housings, we selected a low-silicon, high-thermal-conductivity Al-Mg-Si alloy. This provides a compositional basis for achieving high thermal conductivity and high strength while ensuring semi-solid forming performance.

[0032] 2. Innovative process route: The process organically integrates low-silicon aluminum alloy, air-cooled stirring semi-solid slurry preparation (solidity 25%~35%, slurry temperature 590℃~610℃), laminar flow filling rheological die casting, and T6 solution aging heat treatment (530℃ solution + 170℃ aging) to form a complete process chain that can be industrially mass-produced. This is the first time that a breakthrough has been achieved in allowing semi-solid molded parts of optical module shells to undergo complete T6 heat treatment.

[0033] 3. Structural Integration Innovation: The ultra-thin shell with a wall thickness of only 0.6mm~1.2mm is integrated with multiple functional structures such as the base plate, side walls, sealing edges, heat dissipation microribs, light window mounting platform, positioning threaded column, RF pin slot, and shielding ribs, taking into account the requirements of structural integrity, functional integration and lightweight.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Dense microstructure, suitable for T6 heat treatment: Utilizing semi-solid laminar flow molding, the internal microstructure of the shell is dense, fundamentally eliminating porosity and shrinkage defects inherent in traditional die casting. The shell can undergo complete T6 solution aging heat treatment, overcoming the technical bottleneck of traditional die castings being unable to be brazed or age-strengthened. Vacuum leakage rate ≤1×10⁻⁶ -9 Pa·m 3 / s, meeting the long-term vacuum sealing requirements of high-end optical modules, and compatible with ceramic optical windows and metal cover plate vacuum brazing packaging.

[0035] 2. Excellent overall performance: After T6 heat treatment, the thermal conductivity is ≥145W / (m·K), the tensile strength is ≥330MPa, and the yield strength is ≥210MPa. It achieves both high thermal conductivity and high strength, which is significantly better than traditional die-cast parts with thermal conductivity <120W / (m·K) and tensile strength <250MPa; the electromagnetic shielding effectiveness in the 26~40GHz millimeter wave band is ≥60dB, meeting the anti-interference requirements of high-frequency signal transmission.

[0036] 3. Ultra-thin complex structure integral molding: The ultra-thin shell with a wall thickness of 0.6mm~1.2mm, as well as the micro heat dissipation fins, multiple sets of positioning columns, shielding compartments and other fine structures are cast in one piece without the need for segmented welding, resulting in high molding accuracy and good dimensional stability.

[0037] 4. High material utilization and low overall cost: Only the sealing surface, positioning hole and threaded hole need micro-precision machining, and the rest of the formed surface can be used directly. The material utilization rate is ≥85%, which is more than double that of machining solid aluminum blocks (<40%), and the weight is reduced by 30%~45%. This significantly reduces CNC machining time and material costs, making it suitable for mass industrial production.

[0038] 5. Strong process compatibility: The shell surface is sequentially covered with a conductive passivation layer, a thin nickel layer and a palladium gold plating layer, which is compatible with a variety of packaging processes such as vacuum brazing, laser sealing, and conductive adhesive sealing, and is suitable for diverse application scenarios such as 100G and above high-speed optical modules, silicon photonics chips, and CPO co-packaged optical components. Attached Figure Description

[0039] Figure 1 This is a process flow diagram for the fabrication of a semi-solid-formed aluminum alloy optical module shell. Detailed Implementation

[0040] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0041] It should be noted that, in all aspects of the present invention, the same components or terms in each aspect are described only once in one aspect and not repeatedly, and those skilled in the art should not understand this as a limitation of the present invention.

[0042] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0043] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0044] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto. Experimental methods in the embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used are commercially available; those not specifically sourced are conventional commercially available products in the art.

[0045] Example 1 This embodiment provides a semi-solid molded aluminum alloy optical module housing, which is used to encapsulate an optical module with a transmission rate of 400G.

[0046] The aluminum alloy composition by mass percentage is as follows: Si 0.6%, Mg 0.85%, Cu 0.22%, with the balance being Al, and the total impurity content ≤0.1%. Among these, the control of the impurity element Fe is particularly critical, and the Fe content should be ≤0.08% to avoid coarse needle-like iron-rich phases from cutting the matrix and reducing thermal conductivity and plasticity.

[0047] The semi-solid-formed aluminum alloy optical module housing is prepared according to the following steps: S1. Aluminum Alloy Melting: Weigh aluminum ingots, aluminum-silicon master alloy, aluminum-magnesium master alloy, and aluminum-copper master alloy according to the above proportions. Place the aluminum ingots into the melting furnace and heat to 760℃~780℃ until completely melted. Then, add the aluminum-silicon, aluminum-magnesium, and aluminum-copper master alloys sequentially, stirring until homogeneous. After the master alloys are completely dissolved, adjust the melt temperature to 730℃~750℃. Use a rotary degasser to introduce high-purity nitrogen or argon gas for refining and degassing for 15~20 minutes. Simultaneously, add an appropriate amount of refining agent for slag removal, skimming off surface slag. Let stand for 10~15 minutes to obtain a clean aluminum alloy melt.

[0048] S2. Semi-solid slurry preparation: The refined aluminum alloy molten material is transported to an air-cooled stirring slurry preparation device via an insulated conveying pipeline. The core component of this device is a hollow stirring rod, through which compressed air is introduced to achieve forced cooling of the melt. The stirring device is started, with the stirring speed controlled at 750 r / min, while the compressed air flow rate is adjusted to control the cooling rate. Under the action of low-temperature shear stirring, the primary dendrites in the melt are broken up and spheroidized, forming a uniform spherical crystal structure. Stirring continues until the slurry solidity reaches 30%, at which point the slurry temperature is maintained at 600℃. Through the above air-cooled stirring slurry preparation, a large volume of semi-solid slurry can be prepared within 30 seconds, meeting the needs of continuous industrial production.

[0049] S3. Rheological Die Casting: The prepared semi-solid slurry is smoothly and slowly conveyed to the die-casting mold cavity through an insulated cylinder. The mold preheating temperature is 240℃. The slurry fills the mold cavity in a laminar flow manner, with the filling speed controlled at 0.1~0.3m / s, without splashing or turbulent air entrapment. After filling, the injection cylinder applies increased pressure, and the holding time is 15s. After the holding time is completed, the mold is opened and the blank is removed. The blank is integrally formed into an optical module shell, including a base plate, four side walls, a top sealing edge, built-in heat dissipation microribs, a fiber optic window mounting platform, PCB positioning threaded pillars, RF pin slots, and shielding ribs, etc., with a molded wall thickness of 0.8mm.

[0050] S4. Blank Cooling and Deburring: Place the die-cast blank in a ventilated area to cool naturally to room temperature. Then, place the blank in a vibratory grinding machine, add an appropriate amount of grinding stones and grinding aids, and vibrate and grind for 15-20 minutes to remove flash and burrs. During the grinding process, pay attention to controlling the vibration frequency and grinding time to avoid damaging the shell forming surface.

[0051] S5.T6 Heat Treatment: The deburred blank is placed in a heat treatment furnace and heated to 530℃ for solution treatment and holding for 4-6 hours to allow solute atoms such as Mg and Cu to fully dissolve into the aluminum matrix, while eliminating micro-segregation in the as-cast structure. After solution treatment and holding, the blank is quickly transferred to a quenching tank for water quenching, with a transfer time ≤15s and the quenching water temperature controlled at 60℃-80℃. After quenching, the blank is placed at room temperature for no more than 2 hours, followed by aging treatment at 170℃ for 8-12 hours to allow the strengthening phase to precipitate uniformly and diffusely. Testing shows that the overall deformation of the shell after heat treatment is ≤0.02mm.

[0052] S6. Precision Machining: Micro-CNC milling and drilling / tapping are performed on the sealing edge plane, through holes, and threaded column inner holes of the heat-treated tube blank. The finishing allowance is controlled within the range of 0.1~0.2mm to ensure dimensional accuracy and surface roughness requirements. The remaining forming surfaces are left as die-cast blank surfaces for direct use.

[0053] S7. Surface Coating Treatment: The finished tube shell undergoes degreasing and cleaning, conductive passivation, electroless nickel plating, and palladium-gold plating in sequence. Each process is thoroughly cleaned with deionized water, and after drying, the finished optical module aluminum tube shell is obtained.

[0054] The performance of the optical module housing prepared in this embodiment was tested: thermal conductivity was 152 W / (m·K), tensile strength was 342 MPa, yield strength was 225 MPa; vacuum leak detection rate was 6.3 × 10⁻⁶. -10 Pa·m 3 / s; electromagnetic shielding effectiveness is 63dB in the 26~40GHz millimeter wave band. The material utilization rate of the casing is 87%. Microscopic observation shows that the internal structure is uniform spherical equiaxed crystals with a grain size of 28~42μm, without coarse dendrites, continuous pores, or shrinkage defects.

[0055] Example 2 This embodiment provides a semi-solid molded aluminum alloy optical module housing, which differs from Embodiment 1 in that the alloy composition and some process parameters are different. The housing is used to encapsulate an optical module with a transmission rate of 800G.

[0056] The aluminum alloy composition by mass percentage is as follows: Si 0.4%, Mg 1.1%, Cu 0.30%, balance Al, and total impurity content ≤0.1%.

[0057] The semi-solid-formed aluminum alloy optical module housing is prepared according to the following steps: S1. Same as Example 1.

[0058] S2. The stirring speed is controlled at 900 r / min, and the compressed air flow rate is increased accordingly to achieve a stronger cooling effect. The solid phase of the slurry is controlled at 35%, and the slurry temperature is maintained at 590℃.

[0059] S3. The mold preheating temperature is 260℃, the slurry is filled by laminar flow filling, the filling speed is controlled at 0.1~0.25m / s, the holding time is 12s, and the shell forming wall thickness is 0.6mm.

[0060] S4. Same as Example 1.

[0061] S5.5 is solution treated at 30℃ for 5 hours, then rapidly water-quenched at 60℃, and finally aged at 170℃ for 10 hours. The overall deformation of the shell after heat treatment is ≤0.025mm.

[0062] S6 and S7 are the same as in Example 1.

[0063] The performance of the optical module housing prepared in this embodiment was tested: thermal conductivity was 148 W / (m·K), tensile strength was 335 MPa, yield strength was 218 MPa, and vacuum leak detection rate was 8.1 × 10⁻⁶. -10 Pa·m 3 / s; electromagnetic shielding effectiveness is 61dB in the 26~40GHz millimeter wave band. The material utilization rate of the casing is 86%. Microscopic observation shows that the grain size is 30~45μm, and the structure is uniform and dense.

[0064] Example 3 This embodiment provides a semi-solid molded aluminum alloy optical module housing, which differs from Embodiment 1 in that the alloy composition and some process parameters are different. The housing is used to encapsulate an optical module with a transmission rate of 1.6T.

[0065] The aluminum alloy composition by mass percentage is as follows: Si 0.8%, Mg 0.6%, Cu 0.15%, balance Al, and total impurity content ≤0.1%.

[0066] The semi-solid-formed aluminum alloy optical module housing is prepared according to the following steps: S1. The smelting process is the same as in Example 1.

[0067] S2. The stirring speed is controlled at 600 r / min, the solid phase of the slurry is controlled at 25%, and the slurry temperature is maintained at 610℃.

[0068] S3. The mold preheating temperature is 220℃. The slurry is filled using a laminar flow filling method, with the filling speed controlled at 0.15~0.3m / s and the holding time being 18s. The wall thickness of the tube shell is 1.2mm.

[0069] S4. Same as Example 1.

[0070] S5.5 is solution treated at 30℃ for 6 hours, then rapidly water-quenched at 80℃, and finally aged at 170℃ for 12 hours. The overall deformation of the shell after heat treatment is ≤0.03mm.

[0071] S6 and S7 are the same as in Example 1.

[0072] The performance of the optical module housing prepared in this embodiment was tested: thermal conductivity was 155 W / (m·K), tensile strength was 338 MPa, yield strength was 215 MPa, and vacuum leak detection rate was 5.2 × 10⁻⁶. -10 Pa·m 3 / s; electromagnetic shielding effectiveness is 64dB in the 26~40GHz millimeter wave band. The material utilization rate of the casing is 88%. Microscopic observation shows that the grain size is 25~40μm, and the structure is uniform and dense.

[0073] Example 4 This embodiment provides a semi-solid molded aluminum alloy optical module housing, which differs from Embodiment 1 in that the alloy composition and some process parameters are different. The housing is used to encapsulate an optical module with a transmission rate of 12.8T.

[0074] The aluminum alloy composition by mass percentage is as follows: Si 0.45%, Mg 1.05%, Cu 0.28%, with the balance being Al, and the total impurity content ≤0.1%. Among them, the Fe content is controlled at ≤0.06% to minimize the adverse effects of coarse iron content on high-frequency signal transmission loss.

[0075] The semi-solid-formed aluminum alloy optical module housing is prepared according to the following steps: S1. The smelting process is the same as in Example 1.

[0076] S2. The stirring speed is controlled at 850 r / min, and the compressed air volume is precisely adjusted to achieve rapid and uniform cooling, controlling the slurry solids content at 32% and maintaining the slurry temperature at 595℃. Because the 12.8T optical module has extremely high requirements for the density and dimensional accuracy of the housing, the temperature fluctuation during slurry preparation must be strictly controlled within ±2℃ to ensure the stability and uniformity of the slurry solids content and to ensure the consistent size distribution of spherical crystals in each batch of slurry.

[0077] S3. The mold preheating temperature is 250℃. The slurry is smoothly filled into the mold cavity using a laminar flow filling method, with the filling speed controlled at 0.08~0.15m / s to minimize any minor turbulence disturbances and ensure the ultimate density of the housing under ultra-high frequency applications. The holding time is 16s. The shell molding wall thickness is 0.6mm to meet the stringent requirements of the 12.8T optical module for lightweight and compact housing design. The molding blank includes a complete structure such as a base plate, four side walls, a top sealing edge, built-in heat dissipation microribs, a fiber optic window mounting platform, PCB positioning threaded pillars, RF pin slots, and shielding ribs. The heat dissipation microribs have a thickness of 0.4mm and a spacing of 1.0mm to meet the electromagnetic shielding requirements at higher frequencies.

[0078] S4. Place the die-cast blank in a ventilated area and allow it to cool naturally to room temperature. Control the vibration grinding time to 12-15 minutes, and use fine-grained grinding stones to avoid accidental deformation or damage to the 0.6mm ultra-thin wall structure.

[0079] S5.5 was solution treated at 30℃ for 5 hours, followed by rapid water quenching at 65℃ with a transfer time ≤10s; and then aged at 170℃ for 10 hours to release residual stress. Testing showed that the overall deformation of the shell after heat treatment was ≤0.015mm.

[0080] S6. Perform micro-CNC milling and drilling / tapping on the sealing edge plane, through hole, and threaded column inner hole of the heat-treated tube blank. The finishing allowance is controlled within 0.05~0.10mm, the flatness of the sealing edge plane is controlled within 0.015mm, and the surface roughness Ra≤0.6μm to meet the extremely high precision requirements of the 12.8T ultra-high-speed optical module for the vacuum brazing sealing surface.

[0081] S7. Same as Example 1.

[0082] The performance of the optical module housing prepared in this embodiment was tested: thermal conductivity was 151 W / (m·K), tensile strength was 345 MPa, yield strength was 228 MPa; vacuum leak detection rate was 4.8 × 10⁻⁶. -10 Pa·m 3 / s; the electromagnetic shielding effectiveness in the 26~40GHz millimeter-wave band is 66dB (with shielding effectiveness still ≥63dB in the 35~40GHz high-frequency band), meeting the requirements of the 12.8T ultra-high-speed optical module for extreme electromagnetic compatibility performance. The shell material utilization rate is 86%. Microscopic observation shows that the grain size is 22~38μm, with excellent grain size uniformity, no coarse dendrites, no continuous pores, and no shrinkage defects.

[0083] Comparative Example 1 This comparative example provides an optical module housing prepared using a traditional liquid high-pressure die casting process, for comparison with the technical effects of the present invention.

[0084] The material is made of conventional die-cast aluminum alloy A380, with the following composition by mass percentage: Si 7.5%~9.5%, Cu 3.0%~4.0%, Zn ≤3.0%, and the balance being Al.

[0085] The manufacturing process for optical module shells using traditional liquid high-pressure die casting involves the following steps: A380 aluminum alloy ingots are melted in a melting furnace and heated to 680℃~720℃. After refining, degassing, and slag removal, the liquid metal is directly injected at high speed into the die-casting mold cavity using a turbulent filling method, with a filling speed ≥5m / s. After holding the pressure, the mold is opened, the blank is removed, and it is allowed to cool naturally. Fibers and burrs are removed, and surface treatment is performed. Because traditional die-cast parts contain numerous pores and shrinkage defects, T6 solution aging heat treatment cannot be performed (high-temperature solution treatment causes internal gas expansion, leading to blistering and deformation on the casting surface). Only low-temperature stress-relieving annealing at 200℃ is performed.

[0086] The performance of the optical module housing prepared in this comparative example was tested: thermal conductivity was 105 W / (m·K), tensile strength was 235 MPa, yield strength was 145 MPa; vacuum leak detection showed a leak rate of approximately 1 × 10⁻⁶. -5 Pa·m 3 The shielding efficiency is on the order of / s, which cannot meet the vacuum sealing requirements of high-end optical modules; the electromagnetic shielding effectiveness in the 26~40GHz millimeter-wave band is approximately 35dB. The material utilization rate is approximately 70%. Microscopic observation shows that there are a large number of pores and shrinkage defects inside, and the grains are coarse and dendritic.

[0087] Comparative Example 2 This comparative example provides an optical module housing manufactured using a single-piece aluminum alloy CNC machining process, for comparison with the technical effects of the present invention.

[0088] The manufacturing process uses 6061-T6 Al-Mg-Si alloy forged bars, and proceeds as follows: The 6061-T6 aluminum alloy forged bars are sawn into blanks of the required dimensions, and then subjected to dozens of CNC machining processes, including rough milling of the outer shape, rough milling of the inner cavity, semi-finish milling, finish milling, drilling, and tapping, to mill and hollow out the solid aluminum block into a light module shell. Surface treatment is then performed.

[0089] The performance of the optical module housing prepared in this comparative example was tested: the thermal conductivity was 155 W / (m·K), the tensile strength was 310 MPa, and the yield strength was 276 MPa; the vacuum leakage rate met the requirements; and the electromagnetic shielding effectiveness met the requirements. However, the material utilization rate was only 38%, the processing cycle was as long as several days, the processing cost per piece was extremely high, with CNC machining alone costing several hundred yuan, and the product weight was about 40% heavier than that of this invention, which is not conducive to lightweight integration of equipment.

[0090] Comparative Example 3 This comparative example provides an optical module housing prepared by a forging process, for comparison with the technical effects of the present invention.

[0091] The material used is 6061 aluminum alloy forging billet. The preparation process is as follows: the 6061 aluminum alloy forging billet is heated to the forging temperature and formed into a light module tube shell blank through multiple forging in the forging die. Then, a large number of CNC precision machining processes are carried out (fine structures such as small light window mounting steps, sealing flanges, and small threaded columns cannot be forged in one time and need to be completed by subsequent machining). Finally, T6 heat treatment and surface treatment are carried out.

[0092] The performance of the optical module shell prepared in this comparative example was tested: the thermal conductivity is approximately 150 W / (m·K), the tensile strength is ≥310 MPa, and the vacuum leakage rate meets the requirements. However, the cost of a single mold set is hundreds of thousands of yuan, resulting in high mold investment costs. The molding time for a single part is several minutes, leading to a slow molding cycle. Subsequent CNC machining allowances are large, with the subsequent CNC machining cost for a single part exceeding 30 yuan. Therefore, the overall cost is extremely high for large-scale mass production, making it uneconomical.

[0093] The embodiments described above are merely preferred embodiments of the present invention, but the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A semi-solid molded aluminum alloy optical module housing, characterized in that, The casing is an integrated hollow frame structure, integrally formed by a semi-solid rheo-die casting process, used to encapsulate optical modules with a transmission rate of not less than 100G; the base material of the casing is an Al-Mg-Si aluminum alloy, the composition of which by mass percentage includes: Si 0.4%~0.8%, Mg 0.6%~1.1%, Cu 0.15%~0.3%, with the balance being Al, and the total impurity content of the alloy components is ≤0.1%.

2. The semi-solid formed aluminum alloy optical module housing according to claim 1, characterized in that, The structure of the casing includes a base plate, four side walls, a top sealing edge, built-in heat dissipation microribs, a fiber optic window mounting platform, PCB positioning threaded posts, RF pin slots, and shielding ribs.

3. The semi-solid formed aluminum alloy optical module housing according to claim 1, characterized in that, The shell has a wall thickness of 0.6mm to 1.2mm; the internal microstructure of the shell consists of uniform spherical equiaxed crystals with a grain size ≤45μm, free from coarse dendrites, continuous pores, and shrinkage defects.

4. The semi-solid formed aluminum alloy optical module housing according to claim 1, characterized in that, After undergoing T6 solution aging heat treatment, the tube shell has a thermal conductivity ≥145W / (m·K), tensile strength ≥330MPa, yield strength ≥210MPa, and vacuum leak detection rate ≤1×10⁻⁶. -9 Pa·m 3 / s, and the electromagnetic shielding effectiveness in the 26-40GHz millimeter wave band is ≥60dB.

5. The semi-solid formed aluminum alloy optical module housing according to claim 1, characterized in that, The sealing plane, the light window positioning hole, and the threaded hole of the tube shell are precision machined surfaces, while the remaining forming surfaces are die-cast blank surfaces. The material utilization rate of the tube shell is ≥85%.

6. The semi-solid formed aluminum alloy optical module housing according to claim 1, characterized in that, The surface of the tube shell is sequentially provided with a conductive passivation layer, a thin nickel layer, and a palladium plating layer.

7. A manufacturing process for a semi-solid-formed aluminum alloy optical module housing, characterized in that, Includes the following steps: S1. Aluminum alloy smelting: aluminum ingots and intermediate alloys are added according to the mass ratio of Si 0.4%~0.8%, Mg 0.6%~1.1%, Cu 0.15%~0.3%, with the balance being Al. After melting and holding, refining, degassing and slag removal, aluminum alloy melt is obtained. S2. Semi-solid slurry preparation: The aluminum alloy melt is transported to an air-cooled stirring slurry preparation device, and the dendritic structure is broken by low-temperature shearing and stirring. The solid phase ratio of the slurry is controlled at 25%~35% to obtain a spherical crystal uniform semi-solid slurry. The slurry temperature is maintained at 590℃~610℃. S3. Rheological die casting: The semi-solid slurry is slowly and steadily conveyed to the die casting mold cavity, and filled by laminar flow filling. After holding the cavity pressure for 12-18 seconds, the mold is opened and the blank is removed. S4. Cool the blank to remove burrs. Allow it to cool naturally to room temperature and then use vibratory grinding to remove flash and burrs. S5.T6 heat treatment: the blank is placed at 530°C for solution treatment and heat preservation, followed by rapid water quenching, and then aging treatment at 170°C. After heat treatment, the overall deformation of the shell is ≤0.03mm. S6. Precision machining: Micro-CNC milling and drilling / tapping are performed on the sealing edge plane, through hole, and threaded column inner hole of the heat-treated tube blank. S7. Surface plating treatment: The above-mentioned tube shell is subjected to degreasing and cleaning, conductive passivation, electroless nickel plating, palladium gold plating, and drying to obtain the finished optical module aluminum tube shell.

8. The preparation process according to claim 7, characterized in that, The stirring speed in S2 is 600~900 r / min.

9. The preparation process according to claim 7, characterized in that, The preheating temperature of the die-casting mold in S3 is 220℃~260℃.

10. The application of the semi-solid formed aluminum alloy optical module housing according to any one of claims 1 to 6 in optical module packaging, characterized in that, The encapsulation includes vacuum brazing, laser sealing, or conductive adhesive sealing.

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