A DC-DC cleanroom operation process

Abstract

This invention discloses a process for operating a cleanroom in a DC environment, belonging to the field of plastic frame production technology. The process includes: constructing a vertical positive pressure laminar flow working area from top to bottom, and having operators establish an equipotential electrostatic shielding layer; within the working area, using an air gun equipped with an ion generator, the plastic frames to be treated are swept radially in a unidirectional manner from the inside out at a slight downward angle, utilizing the orthogonal vector superposition of the horizontal thrust of the airflow and the vertical positive pressure laminar flow to suppress micro-dust downwards; on a platform covered with multiple layers of composite viscoelastic dissipative media, the plastic frames are lifted with their reverse side facing upwards and allowed to fall freely due to gravitational potential energy, with damping media buffering against scratches and potential traps adsorbing the falling micro-dust; finally, within the exposure time threshold, the plastic frames are placed in anti-static isolation packaging bags and the openings are sealed with instantaneous pulsed heat and gas, physically freezing them into an ultra-clean state. This invention resolves the physical contradiction between dust removal and desorption and the prevention of stress scratches, completely cutting off the electrostatic back-absorption channel for micro-dust, and significantly improving the first-pass yield of the product appearance.

Description

Technical Field

[0001] This invention belongs to the field of plastic frame production technology, specifically relating to a DC environment cleanroom operation process. Background Technology

[0002] With the development of the display module and high-precision electronic assembly industries, the requirements for cleanliness and appearance yield of products are becoming increasingly stringent. In the assembly process of display modules, the frame, as a core structural component, is highly susceptible to absorbing dust particles from the environment (such as fine dust particles with diameters of 0.3μm and 0.5μm) as well as frame debris left over from injection molding and processing. In particular, the frame often has complex key fastening positions, and these areas, due to their structural characteristics, are prone to becoming blind spots for dirt and grime to accumulate.

[0003] In existing conventional production processes, to remove these attached foreign objects, manual cleaning with an air gun is typically performed in a normal workshop environment, combined with mechanical tapping to shake off stubborn particles. A common method is for operators to hold the plastic frame and tap it directly onto a hard work surface or a flat surface lined with standard packaging bags to dislodge the dust. However, this conventional bottom-treatment process faces intractable physical and micromechanical challenges in actual production: 1) Foreign matter (especially fine dust and frame debris) adhering to the blind spots or corners of the frame has a strong bond with the frame interface due to the combined effects of electrostatic adsorption, liquid bridging, and van der Waals forces. If the applied tapping force is too small, it cannot provide sufficient excitation force to desorb stubborn dust; if the tapping force reaches the desorption threshold for dust removal, the frame will directly impact the rigid work surface or the packaging bag lacking cushioning thickness, resulting in localized stress concentration in a very short contact moment. Due to the limited surface hardness of the polymer frame, this microscopic rigid or semi-rigid collision will inevitably cause process scratches or dents on the surface. Existing work surfaces lack effective viscoelastic cushioning mechanisms, causing frequent process scratches on the frame while cleaning foreign matter, severely reducing the process pass rate (usually only around 93%).

[0004] 2) In typical environments (such as high-concentration dust environments with tens of thousands of 0.3μm particles), the dust particles and frame debris detached by tapping will bounce back elastically upon impact with a non-adhesive hard surface or packaging bag, becoming suspended in the air in the operating area. Simultaneously, the frame easily generates surface static charge during airflow and frictional flow, causing these airborne, bounced dust particles to be rapidly re-adsorbed onto the frame by the airflow vortex. Furthermore, after blowing and tapping, due to the lack of transient microenvironment control mechanisms, foreign matter from the external environment can easily float into the PE bag during the bagging process, rendering the initial mechanical cleaning ineffective and ultimately leading to customer complaints such as "foreign matter explosion" when the product reaches the customer.

[0005] In summary, the core technical problem that urgently needs to be solved in this field is: how to provide sufficient mechanical excitation force to peel off stubborn dust from complex structures (such as snap-fit ​​blind areas) while eliminating stress scratches caused by impacts and collisions from the microscopic interface mechanics level; and how to block the elastic rebound of the peeled dust on the bottom surface and the secondary electrostatic backflow in the air, thereby solving the process problem that dust removal is inevitably accompanied by scratches and secondary pollution after dust removal. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a DC environment cleanroom operation process, which solves the problems in the existing technologies.

[0007] The objective of this invention can be achieved through the following technical solutions: The beneficial effects of this invention are: 1. This invention lays a multi-layered viscoelastic dissipative medium (dust-adhesive pad) on the work surface and limits the gravitational potential energy to 2-4 cm and a specific tapping frequency. Under this technical solution, the deformation of the multi-layered polymer film absorbs the peak impact kinetic energy generated by the tapping, transforming rigid collisions into flexible buffers. At the same time, the highly cross-linked pressure-sensitive adhesive on the surface forms a physical potential well, allowing desorbed dust to be directionally captured. As shown in the data comparison between Example 1 and Comparative Example 1, after introducing this viscoelastic buffering mechanism, the microscopic scratches and bumps on the surface of the frame are significantly reduced, and the process pass rate is increased from 93.1% and stabilized at over 98.9%, successfully protecting the appearance yield of the polymer frame while providing sufficient peel force.

[0008] 2. This invention outputs a vertical positive pressure laminar flow of 0.35~0.45m / s through the top FFU, combined with a horizontal ionized airflow with a slight downward angle of 5°~15° for unidirectional sweeping. On one hand, the ionized airflow effectively neutralizes the static electricity on the surface of the insulating frame, weakening the Coulomb attraction between the dust and the frame; on the other hand, the horizontal thrust and the vertical downward airflow form an orthogonal resultant force, directing the detached dust into the exhaust path below the table. As can be seen from the comparison of the results of Example 1 and Comparative Example 2, this flow field design effectively avoids the formation of rebound vortices in the complex buckle blind area, keeping the residual static electricity peak in the working area within ±18V, and the product DPU (defect rate) steadily reduced to 1.23, effectively overcoming the industry-wide problems of dust suspension and static electricity back-suction in traditional dust blowing processes.

[0009] 3. This invention defines an exposure time window of ≤10s and uses pulse heat sealing technology at 150℃~180℃ to immediately seal the antistatic PE bag. This step, before the microscopic electrostatic field re-accumulates, physically isolates the airflow exchange channels inside and outside the packaging bag. Combined with the test analysis of Comparative Example 3, it can be seen that compared to conventional open or folded packaging, the transient airtight sealing effectively prevents dust leakage due to the breathing effect during subsequent workshop transfers, ensuring the stable maintenance of the results of the initial dust removal work, and reducing the customer complaint rate for foreign objects to zero.

[0010] 4. This invention does not employ complex fully automated dust removal or large-scale electrostatic elimination equipment. Instead, it establishes a highly operable underlying process specification by rigorously defining the physical properties of existing conventional consumables (such as FFU units, adhesive mats, antistatic clothing, and antistatic bags) and combining this with standardized fluid and mechanical operation actions. Based on production data from Examples 1-3, this process solution demonstrates excellent applicability in the production of display module frames of different sizes, consistently keeping the overall material loss rate below 1%. This achieves a substantial leap in product quality while controlling modification costs. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a flow chart of the cleanroom operation process of the present invention. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] like Figure 1 As shown, a DC environment cleanroom operation process includes the following steps: S1, DC field stoking and electrostatic shielding The FFU filter unit is activated above the Class 100 clean booth to continuously output a vertical positive pressure laminar flow from top to bottom into the work space, thereby creating a macroscopic DC field to suppress the intrusion of high-concentration external dust particles and the Brownian motion of internal particles. At the same time, the operator enters the space wearing an anti-static gown and anti-static finger cots to establish an electrostatic shielding layer with the same potential as the environmental boundary within the DC field, thereby initializing a vertical laminar flow work area without electrostatic potential difference.

[0015] Specifically, it includes: S1.1, efficient gas source interception and flow field construction; FFUs (fan filter units, preferably MayAirFFU-1175) are arrayed on the top of the Class 100 clean booth. The internal components are equipped with H14 or higher grade glass fiber high efficiency filters (the filtration accuracy must cover 0.3μm particles and the interception efficiency ≥99.995%). The fans are turned on to continuously output vertical positive pressure laminar flow (DC field) to the working space below.

[0016] S1.2, laminar velocity and micro-positive pressure parameters; Adjust the FFU output power to maintain the average downward air velocity at the height of the work platform within the range of 0.35m / s to 0.45m / s; at the same time, by adjusting the exhaust vent gaps at the bottom of the clean booth, ensure that the booth maintains a slight positive pressure difference of +10Pa to +15Pa relative to the external workshop to prevent high concentration particles (>70,000 particles / L) from penetrating inward.

[0017] S1.3 Selection of materials for dissipating static electricity in the human body; Workers must wear antistatic gowns made of polyester filaments interwoven with conductive fibers (surface resistivity controlled to 10). 6 Ω / sq~10 9 (Ω / sq), and wear halogen-free, silicone-free nitrile rubber antistatic finger cots.

[0018] S1.4, Construction of charge grounding discharge circuit; Workers must connect to the factory's grounding circuit using anti-static wrist straps or conductive shoes to ensure that the ground resistance of the entire operating system is less than 10 ohms. 8 Ω, so that the time constant for the discharge of static charge generated by friction during operation is less than 0.1s.

[0019] S2, Orthogonal Vector Airflow Sweeping The plastic frame to be treated, which has complex snap-fit ​​blind spots and loose foreign matter attached to its surface, is placed in the static-free vertical laminar flow working area. The operator uses an air gun to apply a horizontal vector high-pressure airflow from the inside of the plastic frame to the outside, and controls the horizontal airflow to precisely sweep the snap-fit ​​and structural blind spots of the plastic frame, so that the airflow is sprayed out in the direction of the snap-fit ​​opening. The horizontal airflow pushes the loose dust in the blind spot away from the edge of the plastic frame, and works in conjunction with the vertical positive pressure laminar flow from top to bottom to instantly capture and suppress the free dust, thereby obtaining a plastic frame with no loose floating dust on the surface.

[0020] This step utilizes the principle of positive AC field coupling to remove foreign objects from dead corners while preventing dust from being drawn back in; specifically, it includes the following steps: S2.1, Preparation of ultrafiltration ion gas source; Use an ion gun connected to a clean dry air (CDA) source (preferably the SMC brand IZN10 series). The air source must be treated by an ultra-precision filter with a filtration accuracy of 0.01μm and an oil removal rate of 99.9%. The dew point temperature of the air source must be controlled below -20℃.

[0021] S2.2, Static neutralization and airflow parameters: Start the ion generator and control the ion balance within ±10V; adjust the air gun nozzle output pressure to the range of 0.4MPa~0.6MPa, and strictly control the working distance between the nozzle and the surface of the rubber frame to between 3cm and 5cm.

[0022] S2.3, Vector Radiation Path Control; The operator uses an air gun to sweep the clips and blind spots of the frame. The blowing path must follow a unidirectional trajectory radiating from the geometric center of the frame to the outer edge, and reciprocating swinging is strictly prohibited.

[0023] S2.4, superposition of forces in positive AC field; The air gun's spray axis must form a 5°~15° downward angle with the horizontal operating table surface; the horizontal airflow is used to push the dust away from the rubber frame, and the downward component generated by the downward angle, in conjunction with the vertical downward DC field in step S1, forces the dust to be compressed to the exhaust port below the table surface.

[0024] S3, Viscoelastic Interface Damped Excitation and Transient Adsorption The pre-cleaned frame is placed face down on a viscoelastic dissipative medium (i.e., a dust-adhesive pad) laid on the work surface. Three quantitative taps are applied vertically to each of the four edges of the frame. The viscoelastic dissipative medium absorbs the peak stress at the moment of tapping to avoid rigid impact scratches on the surface of the frame. The polymer colloidal layer on its surface irreversibly adheres to the stubborn micro-dust that has desorbed and fallen due to high-frequency vibration. At the same time, the surface layer of the viscoelastic dissipative medium is peeled off and refreshed every 2 hours to maintain the high activity buffer and adsorption efficiency of the interface, thereby obtaining a highly clean frame with completely removed surface micro-dust and no stress damage.

[0025] This step resolves the mechanical paradox between the desorption threshold and rigid collision damage through media mechanical dissipation, specifically including: S3.1, Definition of multilayer damping composite medium; Lay a multi-layer composite damping dust-adhesive mat (preferably the Korean KM-600 series, with a thickness of 30-60 layers) on the work surface. The thickness of a single LDPE substrate is between 35μm and 50μm, and the interlayer utilizes micro-air gaps and polymer elasticity to provide mechanical cushioning.

[0026] S3.2, Pressure-sensitive adhesive properties and residue control; The surface of the adhesive pad is coated with a high-cohesion water-based acrylic pressure-sensitive adhesive, with a 180° peel strength set between 300g / 25mm and 500g / 25mm. The molecular weight and cross-linking degree of the adhesive must ensure that the cohesive force is much greater than the interfacial adhesion force to the adhesive frame interface, so as to achieve peeling without adhesive residue.

[0027] S3.3, controlled gravitational potential energy quantitative excitation; Place the plastic frame with the reverse side facing up. The operator holds the edge and raises the edge to be struck to a height of 2cm to 4cm from the mat surface. Then release it so that it can use its gravitational potential energy to strike the dust mat vertically. Each of the four edges of the plastic frame needs to perform this action three times in a row, and the striking frequency should be controlled at 1Hz-2Hz.

[0028] S3.4, Dynamic maintenance cycle of interface activity; Strictly implement the surface peeling and refreshing operation of the adhesive pad every 2 hours to prevent interface stiffening and adsorption potential saturation caused by the micro-dust filler effect.

[0029] S4, transient microclimate disruption of high surface energy states After the dust removal action of the plastic frame is completed, within the time threshold before the electrostatic field on the surface of the high-cleanliness plastic frame re-accumulates and generates an adsorption attraction to environmental dust, it is immediately put into a PE bag, and the sealing machine is immediately triggered to heat-seal the PE bag; by cutting off the airflow exchange channel to construct a static micro-climate chamber, the high cleanliness and stress-free state of the plastic frame is physically isolated and frozen, and then the model transfer ticket is attached to complete the packaging, outputting a zero-defect packaged unit that is free from secondary contamination.

[0030] This step aims to complete physical freezing within the window period before the high-cleanliness state disappears, ensuring continued isolation; specifically, it includes: S4.1, Forced execution of transient exposure time window; Define the exposure time from when the adhesive frame detaches from the adhesive pad to when the bag is sealed. The process requires strict time control to ensure... .

[0031] S4.2, Antistatic isolation packaging selection; Use antistatic PE bags (dissipative type) with a thickness of 0.05mm-0.08mm, and control the resistivity of their inner and outer surfaces to within 10. 8 Ω / sq-10 11 The electrostatic discharge rate is between Ω / sq, and the electrostatic decay time must be ≤2.0s.

[0032] S4.3, Pulse hot-press sealing parameter control; Use an instantaneous pulse sealing machine for heat sealing. Set the sealing heating temperature range to 150℃-180℃ (adjust slightly according to the melting point of the PE bag), set the heat pressing holding time to 1.5s-2.5s, and the cooling time after sealing to ≥1.0s.

[0033] S4.4, Physical State Freeze and Marking; The sealed packaging bag must be 100% airtight to eliminate air exchange caused by breathing effects. Then, attach the aircraft type information tag and pack it according to the SOP requirements.

[0034] The technical solution of the present invention will be described below through the following embodiments and comparative examples; Example 1 In this embodiment, a cleaning operation is performed on the frame of a standard 27-inch display module; the specific steps are as follows: Step S1, Environment Initialization Equipment and environmental setup: Class 100 clean booth, with a MayAir FFU-1175 fan filter unit (built-in H14 grade glass fiber HEPA filter) on the top. When turned on, the measured vertical downward air velocity at the center point of the workbench is kept constant at 0.40 m / s. The air curtain is adjusted to maintain a slight positive pressure difference of +12 Pa between the booth and the external workshop.

[0035] Electrostatic shielding: The operator wears a DuPont Tyvek antistatic cleanroom suit and KLEENGUARD G10 antistatic nitrile finger cots. The measured surface resistivity of the protective equipment is [missing value]. The operator wears a grounded wrist strap, and the measured resistance to ground is [value missing]. .

[0036] Step S2, Microscopic Flow Field Cleaning Airflow output settings: Uses a Japanese SMC brand IZN10-11 ion generator air gun, with an SMCAME150 micro-mist separator (filtration accuracy 0.01μm) connected in series at the front end of the air source. Clean, dry air is connected, the measured dew point temperature is -40℃, and the ion balance is adjusted to ±5V; the nozzle output pressure is set to 0.5MPa.

[0037] Blowing: The nozzle is 4cm away from the surface of the rubber frame clip, and the spray axis is at a 10° downward angle to the horizontal work surface. Blow once in a unidirectional radial sweep from the center of the rubber frame to the surrounding edges at a speed of 15cm / s.

[0038] Step S3, Mechanical Excitation and Adsorption Damping medium configuration: The workbench is covered with a multi-layer, washable, dust-free adhesive mat from the Korean brand KM-600. The actual measured thickness of a single layer of LDPE is 40μm, and the 180° peel strength of the acrylic pressure-sensitive adhesive on the surface (according to GB / T2792 standard) is 400g / 25mm.

[0039] Place the cleaned adhesive frame face down, hold both ends and lift it to 3cm above the mat surface, allowing it to fall naturally and impact the adhesive mat using gravity. Tap each of the four sides three times at a frequency of 1.5Hz. Strictly adhere to the procedure of removing the discarded layer of the adhesive mat surface every 2 hours.

[0040] Step S4, sealing the packaging Time window and isolation medium: After the tapping is completed, in The plastic frame was quickly placed into a Jetway brand pink anti-static PE packaging bag with a thickness of 0.06mm (surface resistivity). )middle.

[0041] Place the bag opening into the Hualian PFS-300 foot-operated pulse instant heat sealing machine. Set the heating temperature to 165℃, the heat holding time to 2.0s, and the pressure holding and cooling time to 1.5s. After achieving 100% airtight sealing, pack the bag into a box.

[0042] Example 2 The process steps in this embodiment are the same as those in Embodiment 1, the only difference being: S1: FFU wind speed set to 0.35 m / s, slight positive pressure difference +10 Pa. The surface resistivity of personnel anti-static equipment is... Grounding resistance .

[0043] S2: The output pressure of the ion air gun (same as the model in Example 1) is reduced to 0.4MPa, the working distance is 3cm, the spray angle is 5°, and the sweeping speed is 10cm / s.

[0044] S3: Uses a low-viscosity adhesive pad with a single-layer thickness of 35μm and a peel strength of 300g / 25mm. Lifting height is only 2cm, and tapping frequency is 1.0Hz. The refresh cycle is shortened to 1 hour.

[0045] S4: Execution Exposure Time Use 0.05mm thick antistatic PE bags, sealing temperature 150℃, hot pressing time 1.5s, cooling time 1.0s.

[0046] Example 3 The process steps in this embodiment are the same as those in Embodiment 1, the only difference being: S1: FFU wind speed set to 0.45 m / s, slight positive pressure difference +15 Pa. Surface resistivity of protective equipment. Grounding resistance S2: The output pressure of the ion air gun is increased to 0.6MPa, the working distance is 5cm, the spray angle is 15°, and the sweeping speed is 20cm / s.

[0047] S3: High-adhesion adhesive pad is selected, with a single layer thickness of 50μm and a peel strength of 500g / 25mm. Lifting height is 4cm, and tapping frequency is 2.0Hz. The refresh cycle is set to 1.5 hours.

[0048] S4: Perform extremely short exposure time 0.08mm thick antistatic PE bag (surface resistivity) is used. The sealing temperature is 180℃, the hot pressing time is 2.5s, and the cooling time is 2.0s.

[0049] Comparative Example 1 The process conditions of this comparative example are completely consistent with those of Example 1, with the only difference being the operation interface in step S3.

[0050] Replacement conditions: Remove the Korean KM adhesive mat, and directly tap the rubber frame on a regular hard anti-static tabletop (2mm thick rubber board) or a regular PE bag laid flat on the table. The height remains 3cm, and tap 3 times.

[0051] Comparative Example 2 The process conditions of this comparative example are completely consistent with those of Example 1, with the only difference being the airflow properties and path in step S2.

[0052] Replacement conditions: Use ordinary unfiltered workshop compressed air (without an AME separator, and without passing through an ion generator); and change the air gun blowing angle to vertically downward (90° downward angle) for disordered reciprocating blowing.

[0053] Comparative Example 3 The process conditions of this comparative example are completely consistent with those of Example 1, with the only difference being the packaging isolation method in step S4.

[0054] Replacement conditions: After tapping, place the plastic frame on the workbench to await batch processing (exposure time). ); and put it into a regular insulating transparent PE plastic bag (not anti-static material), and after putting it in, do not use a heat melt sealing machine, but simply fold and stick the bag opening with transparent tape.

[0055] To verify the effectiveness of the DC environment cleanroom operation process described in this invention in solving the problems of dust removal and desorption of the rubber frame, preventing physical scratches, and blocking secondary pollution, the following comparative experiments were conducted.

[0056] I. Basic Experimental Conditions and Sample Preparation Test sample: The "27 Xiangshan QHD" model polymer display module frame was selected as the standard test object.

[0057] Sample size: The initial state (containing injection molding dust and conventional adhering foreign matter) of the plastic frames was treated using the process methods of Examples 1-3 and Comparative Examples 1-3, respectively. 1000 samples were processed for each example and comparative example, and sealed and packaged in batches to ensure statistically significant accuracy.

[0058] Experimental environment: The experimental data acquisition room is set as a standard Class 10,000 (ISO Class 7) cleanroom, with the indoor temperature controlled at 22±2℃ and the relative humidity controlled at 50%±5%RH (strictly in accordance with the ESD electrostatic control environmental standards for electronic products).

[0059] II. Core Indicator Testing Plan and Process Test item 1: Particulate matter adsorption defect rate (DPU value) test; Verify the stripping effect of each process combination on fine dust (especially 0.3μm~0.5μm and above), and its ability to prevent secondary electrostatic back-attraction during the transfer process.

[0060] Testing standards: Referencing optoelectronic industry appearance inspection specifications and customer standards, quantitative scoring is applied to peel strength and residual foreign matter (foreign matter diameter). (Include defects).

[0061] Related hardware equipment: Standard yellow light inspection lamp (selected from Taiwan, China, FUNATEKFL-800 pure yellow light inspection lamp, wavelength 570-590nm).

[0062] High-magnification industrial stereo microscope (Olympus SZ61 selected).

[0063] The testing steps are as follows: 1) In a Class 10,000 laboratory, testing personnel wear anti-static clothing and finger cots.

[0064] 2) Take the sealed (PE bag) plastic frame samples from the examples and comparative examples. In a darkened room under yellow light, the inspector cuts open the PE bag and extracts the plastic frame.

[0065] 3) Adjust the angle of the yellow light to a grazing angle of 30°~45° with the surface of the frame (utilizing the high contrast diffraction effect of yellow light on particles).

[0066] 4) Inspectors conduct visual and microscopic spot checks on the front, back, and blind spots of the four edge clips of the frame.

[0067] 5) Record the findings on each frame. The above are the number of dust and frame debris particles.

[0068] 6) Calculate the DPU (Defects Per Unit) for 1000 samples in each batch: DPU = Total number of defect particles / Total number of samples.

[0069] Test Item 2: Microscopic Impact and Process Scratch Rate Test (First-Pass Yield Assessment) Test objective: To verify the mechanical buffering effect of the viscoelastic dissipative medium (sticky mat) in step S3 in absorbing impact stress.

[0070] Test standard: Refer to the surface micro-damage assessment specification attached to GB / T14216-2008 "Determination of wetting tension of plastic films and sheets" to determine whether there are scratches, indentations or whitening deformation.

[0071] Related hardware equipment: Standard D65 color matching light source box (X-Rite Judge QC selected, illuminance set to 1000 Lux).

[0072] 3D white light interferometer for surface topography (using Bruker Contour GT-K to determine the depth of micro- and nano-scale scratches).

[0073] The testing steps are as follows: 1) Place the plastic frame inside the D65 light source box.

[0074] 2) Conduct a 100% full inspection of the four edges and the reverse contact area of ​​the plastic frame where the hammering operation is carried out.

[0075] 3) If hairline scratches or impact whitening points are observed with the naked eye at 1000 Lux, they are marked as "defective"; for suspected indentations that are difficult to determine with the naked eye, they are scanned using a 3D white light interferometer. If there is a sudden change in local roughness Ra or depth... The injury was determined to be a minor bruise.

[0076] 4) Calculate the process first pass rate: First pass rate = (1000 - number of defective parts with scratches and dents) / 1000 × 100%.

[0077] Test Item 3: Triboelectric Voltage and Dissipation Time Test of User Interface Test objective: To verify the actual suppression and dissipation effects of S1 electrostatic shielding, S2 ion flow neutralization, and S4 antistatic PE bag on triboelectric charging.

[0078] Testing standards: Strictly comply with ANSI / ESDS20.20-2021 and IEC61340-5-1 international standards for electrostatic discharge protection.

[0079] Related hardware equipment: Handheld electrostatic field tester (using the Japanese SIMCOFMX-004, with high testing accuracy) ).

[0080] Electrostatic attenuation tester (Trek156A from the USA was selected).

[0081] Test steps: 1) Neutralization effect test: In the work shed, after the glue frame has been cleaned by step S2 (ion air gun), the residual electrostatic voltage is measured immediately at a distance of 25mm from the surface of the glue frame using SIMCOFMX-004.

[0082] 2) Triboelectric Charging and Packaging Dissipation Test: In step S4, the frictional action of the plastic frame sliding into the PE bag is simulated. At the moment of bagging, a probe is placed close to the outer wall of the PE bag to measure the peak electrostatic voltage, and the electrostatic voltage decays from the peak value to the specified value using a Trek156A instrument. Required electrostatic decay time (seconds).

[0083] Test Item 4: Comparison Test of Particulate Matter Concentration Inside and Outside the Class 100 Cleanroom (Environmental Background Test) Test objective: To verify the macroscopic aerodynamic effect of FFU positive pressure laminar flow in step S1 in terms of dust prevention and dust rebound suppression.

[0084] Testing standard: ISO 14644-1:2015 Cleanroom and related controlled environment standards.

[0085] Related hardware equipment: Laser dust particle counter (USA TSI Aero Trak 9306-V2 model, sampling flow rate 28.3 L / min).

[0086] Test steps: 1) During the operation from S1 to S3 (i.e., the dynamic operation state in which air gun blowing and knocking remove a large amount of dust).

[0087] 2) Place the sampling probe of the TSI particle counter at: ① the workshop passage outside the Class 100 clean booth; ② 20cm above the operating table inside the Class 100 clean booth (to simulate the flow field of the plastic frame).

[0088] 3) Take three consecutive samples, each lasting one minute, record the data and calculate the average value. Measure the particle size per cubic foot (or 28.3 L). and The number of particles.

[0089] The final statistical data for each test item are shown in Tables 1 and 2. All data were measured under controlled laboratory conditions of 22°C and 50% relative humidity, and the sampling volume for particulate matter concentration was a standard 1 cubic foot (28.3L).

[0090] Table 1. Test results of particulate matter adsorption defect rate (DPU) and process pass rate Table 2. Results of electrostatic dynamics and micro-flow field particulate matter concentration tests on the user interface. Based on the above experimental data, the analysis is as follows: 1. Comparing Example 1 and Comparative Example 1, it can be seen that when the multi-layer composite adhesive pad in S3 is removed and quantitative tapping is performed directly on ordinary tabletop adhesive or packaging bags, the process pass rate drops from 98.9% to 93.1% (a large number of microscopic dents and whitening points visible to the 3D interferometer are added). Simultaneously, the DPU value increases from 1.23 to 2.85. Experimental data demonstrates that conventional rigid or semi-rigid tabletops cannot absorb the peak impact kinetic energy generated by tapping, and the detached micro-dust bounces and suspends after elastic collision on a hard surface. The viscoelastic medium introduced in step S3 of this invention not only acts as a mechanical damping spring to absorb destructive energy (preserving high yield), but its polymer pressure-sensitive adhesive potential well also achieves irreversible physical adhesion of the detached micro-dust, completely eliminating secondary dust re-entrainment on the work surface and successfully reconciling the mechanical contradictions of physical dust removal.

[0091] 2. Comparative Example 2 used conventional non-ionized high-pressure air and employed a 90° vertical downward blowing method. As shown in Table 2, the residual electrostatic peak value rose to +2,850V, and the local 0.3μm dust concentration in the operating area increased to 4,860 particles / 28.3L due to airflow interference, resulting in a final DPU deterioration to 3.64 (worst). This comparative example conclusively demonstrates that without ion neutralization, the triboelectric charging of the high-speed airflow can transform the polymer frame into a powerful electrostatic vacuum cleaner. In this invention, S2 cuts off the Coulomb force through ultrafiltration ion flow and constructs horizontal thrust at a micro-pitch angle of 5°~15°, forming an orthogonal superposition with the downward positive pressure flow field of S1, guiding dust directionally to the downward exhaust port and avoiding eddy current interference. In this example, the electrostatic voltage was firmly suppressed within the ±30V safety line, proving that this flow field coupling mechanism is the core of achieving low DPU.

[0092] 3. Although Comparative Example 3 underwent perfect blowing and tapping, it did not strictly adhere to the 10-second time window and used a regular PE bag with a non-airtight folded seal. Results showed that the friction upon entering the bag caused static electricity to rebound to +1,920V. Due to the bag's breathing effect, workshop dust seeped in during its circulation to the outside environment, ultimately causing the DPU to degrade to 3.21. The polymer frame's surface energy was in an excited state after physical cleaning. The data from the examples indicate that only by strictly following step S4 (… Time window + anti-static shielding bag + Only a thermodynamically airtight pulse seal can completely block the airflow channel and prevent microclimate convection and static electricity accumulation.

[0093] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0094] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A process for operating a DC-DC cleanroom, characterized in that, Includes the following steps: S1, a vertical positive pressure laminar flow is output from the top of the clean booth. In the work area, the operator establishes an equipotential electrostatic shielding layer by connecting to the grounding circuit. S2, place the frame to be processed in the working area, and use an air gun with an ion generator to perform a radial unidirectional sweep along the geometric center of the frame outward. The spray axis of the air gun maintains a preset downward angle with the horizontal working surface. Based on the orthogonal vector superposition of the horizontal thrust component generated by the airflow due to the preset downward angle and the downward component of the vertical positive pressure laminar flow, the dust blown away by the airflow is pressed downward. S3, a multi-layer composite viscoelastic dissipative medium coated with pressure-sensitive adhesive is laid on the workbench. The adhesive frame processed in step S2 is placed flat on the viscoelastic dissipative medium with its reverse side facing up. The edge of the adhesive frame is pinched and lifted to a preset height from the surface of the viscoelastic dissipative medium, and then released, so that the adhesive frame falls freely by gravitational potential energy and impacts the viscoelastic dissipative medium vertically. S4. Within the preset exposure time threshold after completing step S3, the plastic frame is completely placed into the antistatic isolation packaging bag, and the opening of the packaging bag is immediately sealed with pulse heat pressure using a hot melt sealing machine.

2. The DC environment cleanroom operation process according to claim 1, characterized in that, In S1, the average downward wind speed of the vertical positive pressure laminar flow at the height of the work platform is 0.35m / s to 0.45m / s; by adjusting the exhaust gap at the bottom of the clean booth, a positive pressure difference of +10Pa to +15Pa is maintained inside the clean booth relative to the external environment.

3. The DC environment cleanroom operation process according to claim 1, characterized in that, The process of establishing the equipotential electrostatic shielding layer includes: the operator wearing a mask with a surface resistivity of... Antistatic clothing within the designated area is connected to the factory grounding system via antistatic wrist straps or conductive shoes, ensuring that the overall operating system's resistance to ground is less than [value missing]. The electrostatic discharge time constant is less than 0.1s.

4. The DC environment cleanroom operation process according to claim 1, characterized in that, In S2, the air source connected to the air gun is dry air that has been sequentially treated with oil removal and 0.01µm precision ultrafiltration. The dew point temperature of the air source is set to below -20℃. The output ion balance of the ion generator is controlled within ±10V.

5. The DC environment cleanroom operation process according to claim 1, characterized in that, In S2, the preset downward angle is 5° to 15°; the working distance between the nozzle of the air gun and the surface of the rubber frame buckle is 3cm to 5cm; and the output pressure of the nozzle of the air gun is 0.4MPa to 0.6MPa.

6. The DC environment cleanroom operation process according to claim 1, characterized in that, In S3, the multilayer composite viscoelastic dissipative medium is a damping adhesive pad with 30 to 60 layers, and the thickness of a single LDPE substrate is 35µm to 50µm; the pressure-sensitive adhesive is a water-based acrylic pressure-sensitive adhesive with a 180° peel strength of 300g / 25mm to 500g / 25mm.

7. The DC environment cleanroom operation process according to claim 6, characterized in that, In S3, the outermost layer of the multilayer composite viscoelastic dissipative medium is peeled off at intervals of 1 to 2 hours to refresh the interface.

8. The DC environment cleanroom operation process according to claim 1, characterized in that, In S3, the preset height is 2cm to 4cm; the four edges of the plastic frame are lifted and released respectively, and each edge is continuously impacted 3 times, and the knocking frequency between the two impacts is controlled within the range of 1Hz to 2Hz.

9. The DC environment cleanroom operation process according to claim 1, characterized in that, In S4, the antistatic isolation packaging bag is a dissipative polyethylene bag with a thickness of 0.05mm to 0.08mm, and the resistivity of its inner and outer surfaces is within a certain range. The electrostatic decay time is less than or equal to 2.0s.

10. The DC environment cleanroom operation process according to claim 1, characterized in that, In S4, the preset exposure time threshold is less than or equal to 10s; the heating temperature of the pulse hot-press gas seal is set to 150℃~180℃, the pulse hot-press holding time is 1.5s~2.5s, and the pressure holding and cooling time after sealing is greater than or equal to 1.0s.

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