Anti-blocking exhaust precision mold for molding complex electronic parts and preparation process of anti-blocking exhaust precision mold

Abstract

The invention provides an anti-blocking exhaust precision die for forming complex electronic parts and a preparation process thereof, the anti-blocking exhaust precision die comprises a die body and at least one exhaust unit, and a cavity is arranged in the die body. The insert is a standard geometry internally provided with a three-dimensional communicated pore network, and the inner walls of pores of the insert and the end face, exposed out of a cavity, of the insert are coated with super-lyophobic fluorosilane molecular layers through vacuum impregnation modification. The insert and the coated high-temperature-resistant sealant are pressed and fixed in the mounting hole of the mold body through interference fit, the end face of the insert is precisely flush with the surface of the cavity, and a buffer cavity communicated with the outside through a vacuum channel is formed in the bottom of the mounting hole. According to the invention, efficient, long-acting and maintenance-free active exhaust is realized, the problems of air trapping and exhaust groove blockage in precision electronic part forming are fundamentally solved, and the product yield and the production efficiency are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of complex electronic molding technology, specifically to a precision mold for preventing material blockage and venting in the molding of complex electronic components, and its manufacturing process. Background Technology

[0002] In the injection molding process of precision electronic components, such as micro connectors, chip packaging shells, and sensor housings, the venting performance of the mold is a core factor determining product yield, appearance quality, and production stability. These parts typically have complex structures, ultra-thin walls, dense ribs, and numerous deep cavities. During high-speed filling, the molten metal easily traps air and gases generated by the thermal decomposition of the material within the cavity, creating trapped gas. If this gas cannot be vented in a timely and complete manner, it will lead to a series of defects such as short shots, burning, internal bubbles, and obvious weld lines, resulting in a large number of scrap products and severely restricting the manufacturing efficiency and reliability of high-end electronic products.

[0003] In existing technologies, gas is guided out by creating channels with a depth of 0.01–0.03 mm on the mold parting surface. However, its venting capacity is limited, and its effect on trapped gas points far from the parting surface, such as the bottom of deep cavities, is minimal. More seriously, shallow channels are easily blocked by waste edges from the cooled melt front or plastic decomposition products, requiring frequent machine shutdowns for manual cleaning, which severely affects production continuity, and the cleaning process may damage the mold.

[0004] In existing technologies, the micron-level clearance between moving parts of the mold is used as an venting channel. This method results in low venting volume and requires extremely high machining precision. If the clearance is too small, venting will be insufficient; if the clearance is slightly large, unacceptable flash will be generated on precision electronic components. Its reliability decreases rapidly with mold wear.

[0005] To improve venting efficiency, existing technologies use mold steel manufactured with a special process, featuring a uniform microporous structure throughout. While this enables surface venting, the material itself is extremely expensive, and its mechanical strength, hardness, and wear resistance are far lower than conventional mold steel, making it unsuitable as a primary load-bearing structure. Furthermore, the entire venting steel component is extremely difficult to process, polish, prevent rust, and clean, resulting in high maintenance costs and limiting its application in large-scale production.

[0006] To address this issue, this invention proposes a precision mold for preventing material blockage and venting in the molding of complex electronic components, along with its manufacturing process. This solution utilizes an assemblable porous metal venting insert. This insert maintains high porosity for efficient venting while ensuring sufficient mechanical properties through an optimized material system and sintering process, allowing it to withstand injection pressure. More importantly, a superhydrophobic coating is attached to the inner wall of its three-dimensional interconnected pores, actively blocking melt wetting and fundamentally preventing pore blockage. This achieves long-lasting, stable, and maintenance-free venting, thus systematically solving the venting problem in precision molding. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To address the shortcomings of existing technologies, this invention provides a precision mold for preventing material blockage and venting in the molding of complex electronic components, as well as its manufacturing process, to solve the problems mentioned in the background art.

[0009] (II) Technical Solution

[0010] To achieve the above objectives, the present invention provides the following technical solution: a precision mold for preventing material blockage and venting in the molding of complex electronic components, comprising a mold body and at least one venting unit, wherein the mold body has a cavity, wherein:

[0011] The exhaust unit includes a set of porous metal exhaust inserts and a mounting structure formed on the mold body;

[0012] The porous metal venting insert is a regular geometric shape with a three-dimensional interconnected pore network inside. The inner walls of the pores and the end face of the insert exposed to the cavity both have a superhydrophobic functional layer.

[0013] The mounting structure includes mounting holes that fit the outer contour of the insert. The insert is fixed in the mounting holes by an interference fit, and its exposed end face is precisely flush with the working surface of the cavity.

[0014] A set of buffer cavities is defined between the bottom of the mounting hole and the insert, and the buffer cavities are connected to an external vacuum system through a vacuum channel opened in the mold body.

[0015] As a further preferred embodiment, the porous metal exhaust insert is sintered from a metal matrix composite material, and its raw material composition, based on the total weight of the metal matrix composite material, includes:

[0016] 70%–85% 316L stainless steel powder;

[0017] Nickel-coated aluminum composite powder 5%–7%;

[0018] 8%–12% Cu-10Sn-3Ti active alloy powder;

[0019] Polycarbonate microspheres 8%–10%;

[0020] Lubricant 0.5%~1.0%.

[0021] As a further preferred option, the mounting hole and the porous metal exhaust insert have an H7 / p6 interference fit, and the interface between the two is filled with a high-temperature resistant sealing material.

[0022] As a further preferred option, a porous metal venting insert is disposed in the venting area of ​​the mold body cavity, and the venting area includes at least one of the following: the end of melt filling, the bottom of blind hole, the end of reinforcing rib, and the abrupt change in wall thickness.

[0023] As a further preferred option, the porous metal exhaust insert is a replaceable modular component.

[0024] A manufacturing process for a precision mold for preventing material blockage and venting includes the following steps:

[0025] ① Preparation of porous metal exhaust inserts: Metal powder is mixed, pressed into shape and then sintered. The sintering process includes degreasing at 450℃, decomposing the pore-forming agent at 750℃ and causing an exothermic nickel-aluminum reaction, and liquid-phase sintering at 1130±10℃. After precision grinding of the sintered body, a fluorosilane molecular layer is grafted onto the inner wall and surface of its pores using a vacuum impregnation method.

[0026] As a further preferred option, precision grinding includes controlling the diameter tolerance of the outer cylindrical surface of the sintered body within ±0.003 mm;

[0027] As a further preferred option, the vacuum impregnation method includes: placing the cleaned sintered body in a vacuum environment, injecting a 1% to 3% heptadecafluorodecyltrimethoxysilane ethanol solution to allow it to penetrate the pores, and then removing and curing it.

[0028] ② Machining the mold body: Machining the cavity, vacuum channel and mounting hole for interference fit with the insert on the mold body. A buffer cavity is reserved at the bottom of the mounting hole and connected to the vacuum channel;

[0029] As a further preferred option, the location of the machining mounting hole is determined by mold flow analysis and is located at the end of the melt filling of the cavity, the bottom of the blind hole, the end of the reinforcing rib, or at the point of abrupt change in wall thickness.

[0030] ③ Integrated assembly: After applying a sealing medium to the outer surface of the insert and / or the inner surface of the mounting hole, the insert is pressed into the mounting hole using the temperature difference method, and the upper end face of the insert is flush with the cavity surface. After curing, the integration of the exhaust unit is completed.

[0031] As a further preferred option, the temperature difference method includes: heating the mold body to 100-120°C while cooling the porous metal venting insert, and then pressing the insert into the mounting hole;

[0032] As a further optimization, after assembly, the upper surface of the insert and the surrounding cavity surface are polished together to control the flatness error within 0.005mm.

[0033] (III) Beneficial Effects

[0034] This invention provides a precision mold for preventing material blockage and venting in the molding of complex electronic components, and its manufacturing process, which has the following beneficial effects:

[0035] This invention employs a porous metal venting insert. The three-dimensional interconnected pore network within the insert forms an ultra-efficient venting channel, with an effective venting cross-sectional area far exceeding that of traditional venting grooves or fine holes. This allows for the instantaneous removal of trapped air from complex structures such as deep cavities and narrow slits, thereby completely eliminating product defects such as incomplete filling, scorching, and bubbles caused by insufficient venting, significantly improving the molding yield of high-precision electronic components. Simultaneously, the inner wall of the pores, after superhydrophobic modification, exhibits a contact angle with the melt greater than 150°. Its extremely strong anti-wetting properties fundamentally block the pathways for melt penetration and solidification blockage, ensuring long-term unobstructed venting channels and eliminating the need for frequent shutdowns for cleaning required by traditional molds. Furthermore, through the synergistic strengthening of the Ni / Al exothermic reaction and Cu-Sn-Ti liquid-phase sintering, this porous metal matrix achieves a compressive strength exceeding 250 MPa, sufficient to withstand the cyclic stress of long-term high-pressure injection. Its service life matches that of the mold steel body, overcoming the limitations of traditional porous materials such as low strength and susceptibility to damage.

[0036] Secondly, in terms of engineering implementation, the inserts are designed as standard geometries, making them plug-and-play functional modules. An H7 / p6 interference fit is used to provide the main load-bearing and sealing. A bottom buffer cavity guides gas flow, and high-temperature resistant sealant is used to fill micro-gaps for secondary sealing. This simplifies the mold body's machining process, requiring only the machining of standard geometric holes and connecting vacuum channels. This avoids the high difficulty and cost of directly machining deep, fine holes or irregularly shaped sealing surfaces on hard mold steel, transforming the design and manufacturing of the mold's venting section from customized processing to efficient standard selection and assembly.

[0037] Finally, regarding reliability, the room-temperature integrated process combining interference fit, sealant, and temperature difference assembly completely avoids the risks of mold deformation, decreased hardness, and increased internal stress that may be caused by high-temperature brazing or sintering, effectively ensuring the original precision and lifespan of the mold body. The rigid mechanical seal provided by the interference fit, combined with the elastic compensation provided by the high-temperature sealant, constitutes a double sealing guarantee, ensuring absolutely no leakage in the vacuum channel even under extreme injection pressure, effectively preventing gas backflow, and ensuring the stability of the molding process and product quality. Attached Figure Description

[0038] Figure 1 This is a flowchart illustrating the preparation process of the precision mold for preventing material blockage and venting according to the present invention. Detailed Implementation

[0039] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] This invention provides a precision mold for preventing material blockage and venting in the molding of complex electronic components, as well as its manufacturing process. The following details the mold structure, key component fabrication, and integration process.

[0041] First, there is a precision mold structure for preventing material blockage and venting in the molding of complex electronic components, including a mold body and at least one venting unit. The mold body is provided with a cavity and a vacuum channel connected to an external vacuum system.

[0042] The exhaust unit includes a porous metal exhaust insert and an installation structure on the mold body.

[0043] Specifically, the porous metal venting insert is a standard cylinder or prism with a three-dimensional interconnected pore network inside, and all the inner walls of the pores and the end faces exposed to the cavity are covered with a superhydrophobic functional layer. As a replaceable modular component, the insert typically ranges in size from 3 to 10 mm in diameter and 5 to 20 mm in height.

[0044] The mounting structure includes a mounting hole that precisely mates with the outer contour of the porous metal venting insert. The porous metal venting insert is pressed into the mounting hole via an H7 / p6 interference fit, and its exposed end face must be precisely flush with the working surface of the cavity. A high-temperature resistant sealing material with a coating thickness of 0.05–0.15 mm is filled between the mating interface, forming a double seal of interference fit and elastic seal. A buffer cavity with a depth of 0.5–2.0 mm is formed between the bottom of the mounting hole and the lower end face of the insert, and this buffer cavity communicates with the vacuum channel.

[0045] Furthermore, the location of the mounting holes was determined through mold flow analysis using the Autodesk Moldflow system. This involved combining the product's 3D geometric model with consideration of pressure and temperature distribution diagrams, setting gate and process parameters for filling analysis, and calculating and labeling the number of inserts and their specific coordinates.

[0046] In other embodiments, mounting holes can be made in conventional gas trapping areas, including the melt filling end, the bottom of blind holes, the end of reinforcing ribs, and the abrupt change in wall thickness, and porous metal venting inserts can be integrated.

[0047] It should also be noted that the high-temperature resistant sealing material is specifically a high-performance silicone sealant or a high-temperature anaerobic planar sealant. In this embodiment, the high-performance silicone sealant is selected from any one of the commercially available Loctite SI 596, Loctite 5972, and 588RTV. The high-temperature anaerobic planar sealant is selected from commercially available Loctite 510 or HR-510.

[0048] Understandably, in a controlled atmosphere sintering furnace, the pore-forming agent decomposes and is discharged to form pores, Ni / Al undergoes an exothermic reaction to generate a reinforcing phase, and Cu-Sn-Ti forms a liquid phase to promote densification and bonding. After cooling, a high-strength porous metal framework is obtained. The reaction synthesis provides a hard reinforcing phase, while the liquid-phase sintering provides a densifying and tough bonding phase. The combination of these two allows the porous material to maintain its porosity while achieving a compressive strength exceeding 250 MPa.

[0049] Furthermore, the insert's outer diameter is slightly larger than the mounting hole diameter at room temperature. During assembly, this generates enormous radial pressure, causing microscopic plastic deformation of the metal surfaces and resulting in a tight fit, forming a physical barrier. At the interference fit interface, a layer of silicone or anaerobic high-temperature resistant sealant is uniformly applied. After curing, this forms an elastic adhesive layer that perfectly fills the tiny gaps caused by microscopic unevenness during processing. These two lines of defense act as backups for each other, ensuring absolutely no leakage in the vacuum channel and preventing the molten metal from seeping into the mating surfaces even under injection pressures reaching hundreds of megapascals.

[0050] Secondly, there is the porous metal exhaust insert, whose raw material composition by mass percentage includes:

[0051] 70%–85% 316L stainless steel powder: serving as the matrix skeleton, providing strength and corrosion resistance. A dual particle size distribution is employed to optimize porosity and strength.

[0052] 5%–7% nickel-coated aluminum (Ni / Al) composite powder: During sintering, an exothermic reaction occurs, Ni + Al → NiAl / Ni3Al, generating a hard reinforcing phase to strengthen the matrix.

[0053] 8%–12% Cu-10Sn-3Ti active alloy powder: as a liquid phase sintering binder, it forms a liquid phase at high temperature, promoting densification and particle bonding.

[0054] 8%–10% polycarbonate microspheres: as a pore-forming agent, they form three-dimensional interconnected pores after thermal decomposition.

[0055] 0.5% to 1.0% lubricant: improves pressing fluidity and completely volatilizes during sintering.

[0056] In this embodiment, commercially available spherical powder of 316L stainless steel is used, and a mixture of coarse powder with a particle size of 45-105μm and fine powder with a particle size of 0-25μm is used. The coarse powder forms a skeleton to ensure the continuity of pores and strength; the fine powder fills the gaps between the coarse powder, improving the density of the green body and the compactness of the matrix after sintering, thereby ensuring high strength while obtaining the required porosity.

[0057] In this embodiment, the nickel-coated aluminum composite powder is selected from commercially available finished products with a particle size of 150-325 mesh. It is matched with stainless steel powder to ensure uniform dispersion, initiating a controllable exothermic reaction locally and avoiding excessive concentration.

[0058] In this embodiment, the Cu-10Sn-3Ti active alloy powder is selected from commercially available finished products with a particle size of 15-53μm.

[0059] In this embodiment, the polycarbonate microspheres are selected from commercially available finished products with a particle size of 50-200 μm. The polycarbonate microspheres are uniformly dispersed in the compact and completely thermally decomposed and volatilized during the sintering heating stage at 300-400℃, leaving space for their original shape and size, thereby forming a pre-designed, interconnected porous structure.

[0060] In this embodiment, the lubricant is selected from commercially available finished zinc stearate, an ultrafine powder with a D50 ≤ 20 μm. It completely volatilizes at 200-400℃ during the initial sintering stage, leaving no residue.

[0061] The porous metal exhaust insert fabrication steps include:

[0062] ① Mixing and molding: Mix the raw materials evenly according to the proportion and then press them into shape.

[0063] ② Staged sintering: carried out in a controlled atmosphere furnace:

[0064] Degreasing: Under a N2 / Ar atmosphere, heat to 450℃ at a rate of 1-2℃ / min and hold for 60-120 minutes to remove the lubricant.

[0065] Pore ​​formation and reaction: The temperature is increased to 750℃ at a rate of 3-5℃ / min and held for 30-60 minutes. During this process, the PC microspheres decompose to form pores, and an exothermic reaction occurs in Ni / Al to generate a reinforcing phase.

[0066] Liquid phase sintering: Heat to 1130±10℃ at 5-8℃ / min and hold for 90-180 minutes. Cu-Sn-Ti forms a liquid phase, achieving final densification and strong bonding. Then furnace cool at 3-5℃ / min.

[0067] Specifically, during the sintering process, at 300-400℃, the PC microspheres completely decompose, leaving behind a three-dimensional porous network; at around 660℃, Ni and Al undergo a violent exothermic solid-phase reaction, with instantaneous local high temperatures reaching over 1500℃, dispersing and generating a high-hardness reinforcing phase; at 800-900℃, the Cu-10Sn-3Ti alloy powder begins to melt, forming an active liquid phase. Under the action of capillary forces, the liquid phase fully wets and encapsulates all solid particles, dissolving and precipitating substances, promoting particle rearrangement and spheroidization of pores, and achieving a strong metallurgical bond to the framework.

[0068] Understandably, the nickel-coated aluminum composite powder undergoes a violent self-propagating exothermic reaction during sintering. The high heat released by the reaction causes the generated NiAl to melt instantly or be in a highly plastic state. Under capillary forces, the molten / softened NiAl preferentially wets and spreads to the nearest and most stable solid surface, namely the pore walls just formed by the decomposition of PC, and solidifies there, forming a composite structure with multi-level roughness. During the subsequent impregnation process, heptadecafluorodecyltrimethoxysilane bonds with the matrix through chemical bonds, and its molecular chains can also fully wet and embed between these microscopic protrusions and depressions. After curing, a significant mechanical interlocking effect is generated between the hydrophobic layer and the matrix. This enhances the adhesion and durability of the hydrophobic layer, enabling it to effectively resist the high temperatures, melt shear, and thermal cycling stress in the injection molding environment, thereby ensuring the long-term stability of the superhydrophobic function.

[0069] ③ Precision machining: Grinding the sintered body, with the outer diameter tolerance controlled within ±0.003mm.

[0070] ④ Superhydrophobic Modification: Using a vacuum impregnation method, the insert is immersed in a 1%–3% heptadecafluorodecyltrimethoxysilane ethanol solution, allowing it to penetrate all pores. After removal, it is cured at 120–150℃ to form a superhydrophobic functional layer. During this process, the micro-nano rough structure formed by the NiAl reaction on the inner wall of the pores provides an enhanced mechanical interlocking effect for the superhydrophobic coating.

[0071] Finally, mold processing and integrated assembly processes:

[0072] ① Mold body machining: Machining the cavity, vacuum channel and mounting hole for interference fit with insert on the mold body. A buffer cavity is reserved at the bottom of the mounting hole and connected to the vacuum channel.

[0073] ②The temperature difference method assembly includes:

[0074] Clean the insert and mounting hole, and apply a sealing medium to the outer surface of the insert and / or the inner surface of the mounting hole. The thickness of the sealing medium is 0.05 mm to 0.15 mm.

[0075] Heat the mold body to 100-120℃ while cooling the insert.

[0076] Quickly press the cooled insert into the heated mounting hole until it touches the bottom.

[0077] Sealant that cures at room temperature or with heat.

[0078] ③ After assembly, polish the insert end face and surrounding cavity together to ensure that the flatness error is controlled within 0.005mm. Connect the vacuum system to conduct an airtightness test.

[0079] When the insert needs to be replaced, follow these steps:

[0080] ①Stop the machine and cool the mold, disconnect the vacuum connection, and remove the mold to the back of the mounting hole.

[0081] ② Identify the insert that needs to be replaced from the cavity surface. Insert a matching ejector pin into the vacuum channel outlet of the mold and gently tap it to eject the faulty insert from the back.

[0082] ③ Use a copper wire brush, cotton swabs, and anhydrous ethanol to thoroughly remove any remaining old sealant, oxides, or contaminants from the mounting holes. Continue cleaning until a clean metal surface is exposed.

[0083] ④ After applying a sealing medium to the outer surface of the new insert of the same specification and / or the inner surface of the mounting hole, press the insert into the mounting hole using the above-mentioned temperature difference method, and then re-polish the end face.

[0084] To further understand the present invention, the following description, in conjunction with embodiments, illustrates the precision mold for preventing material blockage and venting provided by the present invention. The scope of protection of the present invention is not limited by the following embodiments.

[0085] Example 1

[0086] Molds used for forming miniature LCP connectors, manufacturing high pin count miniature LCP connectors with thin walls of 0.25mm, dense ribs, and deep blind holes;

[0087] Arrangement of porous metal exhaust inserts: Through Moldflow analysis, a total of 6 exhaust units are set at the ends of 4 ribs and the bottom of 2 deep blind holes.

[0088] Perforated metal exhaust insert specifications: Uses Φ3×8mm standard cylindrical inserts to adapt to narrow spaces.

[0089] Mounting hole design: A Φ2.985 H7 mounting hole is machined at a specified position in the cavity to fit with the Φ3p6 insert, with a single-sided interference of 0.01mm and a hole depth of 7.5mm, forming a 0.5mm deep buffer cavity, and a Φ2mm vacuum channel is connected at the bottom.

[0090] Sealing: Loctite 5972 silicone sealant was used, with a coating thickness of 0.08mm.

[0091] Preparation and assembly process:

[0092] Fabrication of porous metal exhaust inserts:

[0093] ① The mixture of 78% 316L stainless steel powder, 5% nickel-coated aluminum composite powder, 8% Cu-10Sn-3Ti active alloy powder, 8% polycarbonate microspheres and 1.0% zinc stearate is uniformly mixed and then pressed into shape.

[0094] ② Staged sintering: carried out in a controlled atmosphere furnace:

[0095] Degreasing: Under N2 atmosphere, heat to 450℃ at a rate of 1℃ / min and hold for 60 minutes.

[0096] Hole formation and reaction: Heat to 750℃ at 3℃ / min and hold for 30 minutes.

[0097] Liquid phase sintering: Heat to 1130±10℃ at 5℃ / min and hold for 90 minutes. Then furnace cool at 3℃ / min.

[0098] ③ Precision machining: The sintered body is centerlessly ground to Φ3.000±0.003mm.

[0099] ④ Vacuum impregnation with 1.5% fluorosilane solution, then remove and cure at 120℃.

[0100] Mold machining: The cavity is made of S136 mold steel and mirror polished. The mounting holes are precision machined using a coordinate grinding machine.

[0101] Assembly: The mold is heated to 110℃, and the insert is pressed in after being cooled with liquid nitrogen for 3 minutes. After curing, it is polished together to achieve a flatness of ≤0.005mm.

[0102] Example 2

[0103] Molds for thin-walled PC / ABS sensor housings, used to manufacture thin-walled sensor housings with curved surfaces and numerous mounting posts, resulting in a large projected area. The product material is PC / ABS alloy.

[0104] Porous metal exhaust insert arrangement: Through Moldflow analysis, eight exhaust units were set in the five areas that were last filled around the part and on top of the three high ribs.

[0105] Specifications of porous metal exhaust inserts: Φ6×12mm inserts are used in the main area, and Φ4×10mm inserts are used at the top of the bone.

[0106] Installation and sealing: Mounting holes are machined to H7 / p6, with a buffer cavity depth of 1.0mm. Use 588 RTV silicone sealant.

[0107] Preparation and assembly process:

[0108] Fabrication of porous metal exhaust inserts:

[0109] ① The mixture of 76% 316L stainless steel powder, 5% nickel-coated aluminum composite powder, 8% Cu-10Sn-3Ti active alloy powder, 10% polycarbonate microspheres and 1.0% zinc stearate is mixed evenly and then pressed into shape.

[0110] ②The staged sintering steps are the same as in Example 1;

[0111] ③ Precision machining: The sintered body is centerlessly ground to Φ6.000±0.003mm or Φ4.000±0.003mm.

[0112] ④ Vacuum impregnation with 2% fluorosilane solution, then remove and cure at 120℃.

[0113] Mold processing: The cavity is made of S136 mold steel and mirror polished. Mounting holes are machined on the side wall (non-parting surface) of the mold, and vacuum channels are connected through internally drilled oblique holes, realizing "surface venting" in complex structures. The mounting holes are precision machined using a coordinate grinding machine.

[0114] Assembly: The mold is heated to 110℃, and the insert is pressed in after being cooled with liquid nitrogen for 3 minutes. After curing, it is polished together to achieve a flatness of ≤0.005mm.

[0115] Results: Completely eliminated scorching defects around the outer shell, achieving Grade A appearance quality for the product. Injection speed was increased by approximately 40%, cycle time was shortened, and production efficiency was significantly improved.

[0116] Example 3

[0117] Molds for PEEK high-temperature connectors are used to manufacture high-temperature resistant PEEK connectors with embedded precision metal terminals.

[0118] Multi-hole metal exhaust insert arrangement: Four miniature exhaust units are set in the surrounding area of ​​the metal terminal head and tail.

[0119] Specifications of porous metal exhaust insert: Uses a small-sized insert of Φ4×8mm, precisely positioned 0.5mm away from the metal insert.

[0120] Installation and Sealing: Mounting holes are machined to H7 / p6, with a buffer cavity depth of 1.0mm. Loctite SI 596 sealant is selected to match the extreme process temperatures of PEEK.

[0121] Preparation and assembly process:

[0122] Fabrication of porous metal exhaust inserts:

[0123] ① The mixture of 72.5% 316L stainless steel powder, 7% nickel-coated aluminum composite powder, 12% Cu-10Sn-3Ti active alloy powder, 8% polycarbonate microspheres and 0.5% zinc stearate is uniformly mixed and then pressed into shape.

[0124] ②The staged sintering steps are the same as in Example 1;

[0125] ③ Precision machining: The sintered body is centerlessly ground to Φ4.000±0.003mm.

[0126] ④ Vacuum impregnation with 3% fluorosilane solution, then remove and cure at 150℃.

[0127] Mold machining: The cavity is made of S136 mold steel and mirror polished. The mounting holes are machined using wire EDM.

[0128] The assembly is the same as in Example 1. However, the pressing stroke must be strictly controlled to ensure the distance from the metal insert.

[0129] Results: During continuous production at a mold temperature of 400℃, the insert function remained stable, with no sealing failures or coating decomposition observed. The product airtightness test yield reached 100%.

[0130] Comparative Example 1

[0131] The most common venting design in the industry is adopted. Venting grooves are created on the mold parting surface in the final melt filling area. The venting grooves consist of two sections: a sealing section near the cavity, 0.02mm deep, 1.5mm long, and 5mm wide, and a subsequent venting section, 0.2mm deep. No other porous inserts or active venting devices are used. This design is applied to the production of the miniature LCP connector in Example 1.

[0132] Comparative Example 2

[0133] The venting insert, mold processing, and assembly were carried out using the same preparation steps as in Example 1. However, the venting insert did not require vacuum impregnation with a fluorosilane solution. It was then applied to the production of the miniature LCP connector in Example 1.

[0134] Comparative Example 3

[0135] The preparation of the porous metal exhaust insert and the mold processing are the same as in Example 1.

[0136] A high-temperature vacuum brazing process is used to metallurgically connect the insert to the mold body to achieve a high-strength, high-airtightness fixation. This process is applied to the production of the miniature LCP connector in Example 1.

[0137] Test example:

[0138] The filling end pressure / trapping index of the molds in Example 1 and Comparative Examples 1 to 3 were predicted and detected using the mold flow analysis software (Autodesk Moldflow). The specific results are shown in Table 1.

[0139] According to the appearance inspection standard for injection molded parts, the molds in Example 1 and Comparative Examples 1 to 3 were continuously produced for 10,000 cycles. The defect rate caused by trapped air (burning, material shortage) was statistically analyzed. The specific results are shown in Table 1.

[0140] Through long-term operation testing, the product defect rate of the molds in Example 1 and Comparative Examples 1 to 3 after every 50,000 mold cycles was monitored, and the changes in yield and insert status were observed. The specific results are shown in Table 1.

[0141] The hardness around the mold insert mounting holes (0.5 mm from the hole wall) in Example 1 and Comparative Examples 1 to 3 was measured according to ISO 6507-1, and the key cavity dimensions before and after assembly were compared. The specific results are shown in Table 1.

[0142] By simulating a complete insert replacement process, recording the time, material costs, and treatment of the mold body, the time, cost, and impact on production of the mold replacement operation in Example 1 and Comparative Examples 1 to 3 are evaluated. The specific results are shown in Table 1.

[0143] Table 1. Test statistics for each embodiment and comparative example.

[0144]

[0145] In summary, this invention provides a precision mold for preventing material blockage and venting in the molding of complex electronic components, along with its manufacturing process. A porous metal material is prepared using 316L stainless steel as a framework. A pore-forming agent is added to form a three-dimensional interconnected pore network, serving as an efficient venting channel. Nickel-coated aluminum powder is introduced, utilizing its intense in-situ exothermic reaction during sintering to generate a hard reinforcing phase, ensuring the porous structure possesses a high strength exceeding 250 MPa. Simultaneously, Cu-Sn-Ti active alloy powder is added, achieving strong and tough metallurgical bonding between particles through liquid-phase sintering. Finally, vacuum impregnation technology is used to firmly graft fluorosilane molecules onto the inner walls of the pores, forming a superhydrophobic functional layer, thereby physically preventing melt penetration and blockage.

[0146] By manufacturing the above materials into standard cylindrical or prismatic inserts, a plug-and-play venting module is formed. In terms of integration technology, this solution abandons traditional high-temperature brazing or welding, adopting a room-temperature integration strategy of precision interference fit + high-temperature resistant sealing + temperature difference assembly. Press fitting is easily achieved through the instantaneous dimensional difference generated by heating the mold and cooling the inserts, and the sealant cures at room temperature. This process ensures connection strength and absolute airtightness while avoiding mold steel annealing, deformation, and internal stress problems caused by thermal connections, perfectly protecting the precision and lifespan of the high-value mold body. Furthermore, the modular design allows any insert to be quickly ejected and replaced from the back of the mold after failure, simplifying maintenance from complex mold repair to the replacement of standard parts.

[0147] This technical solution systematically solves the venting problem in precision molding through synergistic innovation of "functional materialization," "structural modularization," and "integrated harmlessness." Compared with traditional technologies, it achieves orders-of-magnitude improvements in venting efficiency, long-term stability, mold protection, and maintainability. It provides a reliable guarantee for zero-defect manufacturing of highly complex and high-precision electronic components.

[0148] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A precision mold for preventing material blockage and venting in the molding of complex electronic components, comprising a mold body and at least one venting unit, wherein the mold body has a cavity, characterized in that: The exhaust unit includes a set of porous metal exhaust inserts and an installation structure formed on the mold body; The porous metal exhaust insert is a regular geometric body with a three-dimensional interconnected pore network inside. The inner wall of the pores and the end face of the insert exposed to the cavity both have a superhydrophobic functional layer. The mounting structure includes a mounting hole that fits the outer contour of the insert. The insert is fixed in the mounting hole by an interference fit, and its exposed end face is precisely flush with the working surface of the cavity. A set of buffer cavities is defined between the bottom of the mounting hole and the insert, and the buffer cavities are connected to an external vacuum system through a vacuum channel opened in the mold body.

2. The precision mold for preventing material blockage and venting according to claim 1, characterized in that, The porous metal exhaust insert is sintered from a metal matrix composite material, and its raw material composition, based on the total weight of the metal matrix composite material, includes: 70%–85% 316L stainless steel powder; Nickel-coated aluminum composite powder 5%–7%; 8%–12% Cu-10Sn-3Ti active alloy powder; Polycarbonate microspheres 8%–10%; Lubricant 0.5%~1.0%.

3. The precision mold for preventing material blockage and venting according to claim 1, characterized in that, The mounting hole and the porous metal exhaust insert are H7 / p6 interference fit, and the interface between the two is filled with high-temperature resistant sealing material.

4. The precision mold for preventing material blockage and venting according to claim 1, characterized in that, The porous metal venting insert is disposed in the gas trapping area of ​​the mold body cavity, and the gas trapping area includes at least one of the following: the end of melt filling, the bottom of blind hole, the end of reinforcing rib, and the abrupt change in wall thickness.

5. The precision mold for preventing material blockage and venting according to claim 1, characterized in that, The porous metal exhaust insert is a replaceable modular component.

6. A method for preparing a precision mold for preventing material blockage and venting as described in any one of claims 1 to 5, characterized in that, Includes the following steps: ① Preparation of porous metal exhaust inserts: Metal powder is mixed, pressed into shape and then sintered. The sintering includes degreasing at 450℃, decomposing the pore-forming agent at 750℃ and causing an exothermic nickel-aluminum reaction, and liquid-phase sintering at 1130±10℃. After precision grinding of the sintered body, a fluorosilane molecular layer is grafted onto the inner wall and surface of its pores using a vacuum impregnation method. ② Machining the mold body: Machining the cavity, vacuum channel and mounting hole for interference fit with the insert on the mold body, wherein a buffer cavity is reserved at the bottom of the mounting hole and communicates with the vacuum channel; ③ Integrated assembly: After applying a sealing medium to the outer surface of the insert and / or the inner surface of the mounting hole, the insert is pressed into the mounting hole using a temperature difference method, and the upper end face of the insert is made flush with the cavity surface. After curing, the integration of the exhaust unit is completed.

7. The method according to claim 6, characterized in that, The vacuum impregnation method includes: placing the cleaned sintered body in a vacuum environment, injecting a 1% to 3% heptadecafluorodecyltrimethoxysilane ethanol solution to allow it to penetrate the pores, and then removing and curing it.

8. The preparation process according to claim 6 or 7, characterized in that, The temperature difference method includes: heating the mold body to 100-120°C while cooling the porous metal venting insert, and then pressing the insert into the mounting hole.

9. The preparation process according to claim 6, characterized in that, The location of the mounting hole is determined by mold flow analysis and is located at the end of the melt filling of the cavity, the bottom of the blind hole, the end of the reinforcing rib, or at the point of abrupt change in wall thickness.

10. The preparation process according to claim 6, characterized in that, The precision grinding includes controlling the diameter tolerance of the outer cylindrical surface of the sintered body within ±0.003mm; and controlling the flatness error between the upper end face of the insert and the surrounding cavity surface within 0.005mm.

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