Film pressing method for reducing reject ratio of FMM bamboo joint lines

Abstract

The invention discloses a film pressing method for reducing the reject ratio of FMM bamboo joint lines, and belongs to the technical field of fine metal mask manufacturing. The method comprises the following steps: in a film pressing process, maintaining the temperature of a film pressing cavity at 99-101 DEG C; the film pressing pressure is 0.4 MPa, and the pressure maintaining time is 20-30 minutes. By means of the film pressing method, the bamboo joint line mura reject ratio can be remarkably reduced, and meanwhile it is guaranteed that other core performance of a product meets the requirements.

Description

Technical Field

[0001] This invention relates to the field of fine metal photomask manufacturing technology, specifically to a lamination method for reducing the defect rate of bamboo-like patterns in FMM (fine metal mask). Background Technology

[0002] In the FMM (Fine Metal Mask) industry, MAC (Macroscopic Inspection) is a key quality control step before FMM products leave the factory. Its core inspection indicators include the flatness of the invar surface, the amount of defect residue, and the consistency of texture. Among them, bamboo-like mura (i.e., the invar surface exhibits an uneven texture defect resembling bamboo joints) is the main problem affecting the product's qualification.

[0003] Currently, the vacuum laminating machine used in FMM product manufacturing has a conventional lamination temperature set at 110℃. This temperature parameter was formulated based on the characteristics of early substrates. However, as FMM substrates are upgraded to be thinner (e.g., 25um, 10um), the lamination temperature of 110℃ is no longer suitable. On the one hand, high temperature will cause uneven local thermal shrinkage of the dry film on the substrate surface during the lamination process, forming periodic textures (i.e., bamboo-like mura) along the lamination direction. On the other hand, high temperature will exacerbate the thermal stress between the lamination roller and the substrate, further amplifying the visual detection effect of bamboo-like mura. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a lamination method for reducing the defect rate of FMM bamboo-textured patterns.

[0005] The objective of this invention can be achieved through the following technical solutions: A first aspect of the present invention relates to a method for laminating a fine metal photomask, comprising the following steps: During the membrane pressing process, the temperature of the membrane pressing chamber is maintained at 99–101 degrees Celsius; the membrane pressing pressure is 0.4 MPa, and the pressure is maintained for 20–30 minutes.

[0006] Optionally, preheating can be performed before pressing by heating the pressing cavity to 98 degrees Celsius and maintaining it for 10 minutes.

[0007] Optionally, a vacuum of 50 Pa is maintained during the molding process.

[0008] Optionally, a temperature detector is provided in the pressure chamber, and the temperature signal detected by the temperature detector is connected to a PID control unit, which controls the heating device and the heat dissipation device to adjust the temperature in real time.

[0009] Optionally, if the temperature is below 99°C, increase the heating power; if the temperature is above 101°C, stop heating and start the cavity cooling fan.

[0010] Optionally, the control parameters of the PID control unit are configured as follows: proportional coefficient P = 2.5, integral time I = 60s, and derivative time D = 5s.

[0011] Optionally, the temperature detector is a thermocouple.

[0012] A second aspect of the present invention relates to a vacuum pressing apparatus, comprising: Pressure membrane cavity; Heating and heat dissipation devices are used for heating and cooling the pressure film cavity, respectively. A temperature detector is installed in the pressure film cavity; A film-pressing mechanism for performing film pressing; A vacuum system used to create and maintain a vacuum level in a pressure film cavity; And a PID control unit, used to control the heating and heat dissipation devices to maintain the temperature in the pressure chamber at 99-101 degrees Celsius.

[0013] Optionally, the control parameters of the PID control unit are configured as follows: proportional coefficient P = 2.5, integral time I = 60s, and derivative time D = 5s.

[0014] Optionally, the temperature detector is a thermocouple.

[0015] The beneficial effects of this invention are: 1. Significantly reduced bamboo-textured mura defect rate: After optimizing the lamination temperature to 100℃, the uneven thermal shrinkage of the dry film on the substrate surface was significantly suppressed. Verified by MAC appearance inspection, the bamboo-textured mura defect rate dropped from 90% to below 5%, completely solving the core defect problem of FMM products. 2. Improved product yield and production efficiency: The reduction of defective bamboo-textured mura products improves the overall yield of FMM products, eliminating the need for extensive screening and removal of defective products, thus significantly increasing production efficiency; 3. High temperature control stability: The added closed-loop temperature control system can stabilize the film pressing temperature within the range of 100℃±1℃, avoiding the temperature fluctuation of ±3℃ in traditional equipment, ensuring the quality consistency of different batches of FMM products, with a batch-to-batch difference in bamboo texture mura detection of less than 2%; 4. Significant compatibility and cost advantages: This temperature optimization solution does not require modification of the overall structure of the vacuum laminator, only adjustment of temperature parameters, eliminating the need for equipment modification costs; at the same time, a 10°C temperature reduction can reduce the energy consumption of the heating module, greatly reducing the average daily power consumption of a single vacuum laminator and further reducing the enterprise's energy costs. Attached Figure Description

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] Figure 1 The diagram shows the product before and after the improvements in this application; Figures 2-4 The diagrams show the test results for TPX, TPY, and TPST in this application, respectively. Detailed Implementation

[0018] 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.

[0019] In some embodiments of the present invention, an FFM lamination process method is provided.

[0020] The equipment used in this invention is a vacuum film press, manufactured by SEKITECH, model: JVL-500.

[0021] In some examples, to ensure the stability of the substrate temperature during the lamination process, the vacuum lamination equipment can be modified as follows: Retain the original heating element (5kW) of the vacuum laminator, and install one K-type high-precision thermocouple (temperature range 0-200℃, accuracy ±0.5℃) at each of the four positions (top, bottom, left, and right) of the lamination chamber. The thermocouple probes should extend 50mm into the lamination chamber to ensure direct monitoring of the actual temperature near the substrate. Connect the thermocouple signals to a newly added PID control unit (model: OMRONE5CC). The PID unit will be linked with the main control system of the vacuum laminator to achieve real-time temperature data acquisition and automatic adjustment of the heating power.

[0022] In some examples, the vacuum laminator can be configured with the following parameters: The target laminator temperature can be set to 100℃ via the laminator's control panel, and the allowable temperature fluctuation range can be set to ±1℃. Simultaneously, the laminator holding time can be stabilized, and the laminator pressure can be kept constant at the traditional parameter (0.4MPa) to avoid pressure variations affecting other product properties.

[0023] Before each batch of production, four thermocouples are calibrated using a standard temperature calibrator (accuracy ±0.2℃) to ensure accurate temperature measurement data. The control parameters of the PID control unit (proportional coefficient P=2.5, integral time I=60s, derivative time D=5s) are checked weekly to avoid temperature runaway caused by parameter drift.

[0024] 2. Operating Procedures: (1) Preheating stage: Start the vacuum press machine and issue a 100℃ pressing temperature command through the main control system. The PID adjustment unit drives the heating tube to work, and the thermocouple provides real-time feedback on the pressing roller temperature. When the temperature reaches 98℃, the heating power is automatically reduced and the machine enters the constant temperature preheating state. The preheating time is maintained for 10 minutes to ensure that the temperature of each area of ​​the pressing roller is uniform. (2) Pressing stage: Place the FMM substrate (thickness 35μm, width 225mm) into the pressing cavity, close the cavity and start the vacuum system (vacuum degree 50Pa). After the vacuum degree reaches the standard, the heating module maintains the temperature at 100℃, and the pressing mechanism applies a pressure of 0.4MPa to enter the pressure holding stage (pressure holding time 20min). During the pressure holding process, the PID adjustment unit monitors the temperature in real time. If the temperature is lower than 99℃, the heating power is automatically increased to 3kW. If the temperature is higher than 101℃, the heating is stopped and the cavity cooling fan (power 500W) is started to ensure that the temperature is stable within the target range. 3. Effect Verification: (1) Defect rate verification: In the actual application of a certain FMM manufacturing enterprise, after adopting this technical solution, 500 FMM products were produced continuously. After MAC appearance inspection, only 22 pieces were found to have slight bamboo joint texture mura (defect rate 4.4%), which is 85.6 percentage points lower than the traditional 110℃ lamination process (450 defective pieces, defect rate 90%). (2) Stability verification: The production process was continuously monitored for 30 days. The temperature fluctuation range of the vacuum laminator was controlled within 99.2-100.8℃, and the temperature stability compliance rate was 100%. The maximum difference in the detection rate of bamboo texture mura among different batches of products was only 1.8%. (3) Performance Verification: The optimized FMM products underwent MAC appearance inspection, and the test results all met industry standards, proving that the combination of 100℃ pressing temperature and stable holding time solved the bamboo texture mura problem without affecting other core performance characteristics of the product. With a holding time ≥20min and other process conditions being the same, the tensile strength of the mechanical properties was >850Mpa, the overall PPI characteristics met expectations, and the TPST and TPX / Y performance of the product met expectations, with a process capability >1.33.

[0025] The test method and standard for tensile strength are: CUCK MA SHEE NE measurement method, standard ≥850Mpa.

[0026] The testing methods and standards for TPST and TPX / Y are as follows: TPCD equipment measurement, 0±15um, 0±15um, 0±2.5um (calculated and generated by minitab), test results are as follows: Figure 2 As shown.

[0027] The test results are shown in the table below: 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.

[0028] 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 method for laminating a fine metal photomask, characterized in that, Includes the following steps: During the membrane pressing process, the temperature of the membrane pressing chamber is maintained at 99–101 degrees Celsius; the membrane pressing pressure is 0.4 MPa, and the pressure is maintained for 20–30 minutes.

2. The method for laminating a fine metal mask according to claim 1, characterized in that, Preheat the molding chamber to 98 degrees Celsius and maintain the temperature for 10 minutes before molding.

3. The method for laminating a fine metal mask according to claim 1, characterized in that, Maintain a vacuum of 50 Pa during the molding process.

4. The method for laminating a fine metal photomask according to claim 1, characterized in that, A temperature detector is installed in the pressure chamber. The temperature signal detected by the temperature detector is connected to a PID control unit. The PID control unit adjusts the temperature in real time by controlling the heating device and the heat dissipation device.

5. The method for laminating a fine metal mask according to claim 4, characterized in that, If the temperature is below 99℃, increase the heating power; if the temperature is above 101℃, stop heating and start the cavity cooling fan.

6. The method for laminating a fine metal photomask according to claim 4, characterized in that, The control parameters of the PID control unit are configured as follows: proportional coefficient P = 2.5, integral time I = 60s, and derivative time D = 5s.

7. The method for laminating a fine metal photomask according to claim 4, characterized in that, The temperature detector is a thermocouple.

8. A vacuum film pressing device, comprising: Pressure membrane cavity; Heating and heat dissipation devices are used for heating and cooling the pressure film cavity, respectively. A temperature detector is installed in the pressure film cavity; A film-pressing mechanism for performing film pressing; A vacuum system used to create and maintain a vacuum level in a pressure film cavity; And a PID control unit, used to control the heating and heat dissipation devices to maintain the temperature in the pressure chamber at 99-101 degrees Celsius.

9. The vacuum film pressing equipment according to claim 7, characterized in that, The control parameters of the PID control unit are configured as follows: proportional coefficient P = 2.5, integral time I = 60s, and derivative time D = 5s.

10. The vacuum film pressing equipment according to claim 7, characterized in that, The temperature detector is a thermocouple.

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