Clean detection method for non-volatile residues (NVR)

Abstract

The invention relates to a clean detection method for non-volatile residues (NVR). Accurate measurement of the NVR is realized mainly through the steps of sampling, extracting, filtering, baking, weighing, calculating and the like. The NVR cleanliness detection method is convenient and rapid in sampling, high in measurement precision and suitable for rapid NVR detection of the surface of a machined part and the surface of an optical element.

Description

Technical Field

[0001] The invention is applicable to the field of clean detection, in particular to a non-volatile residue (NVR) clean detection method. Background Art

[0002] Optical components are easily damaged by contamination under the influence of high-flux lasers, so cleanliness is particularly important for high-power laser devices, which usually work in a Class 100 clean environment. Common pollutants in high-power laser devices are generally divided into two categories: particulate matter and organic matter. Particulate matter can generally be removed by cleaning and wiping, detected by flushing and filtering, or identified by the naked eye with the assistance of ultraviolet light. Organic pollutants, especially non-volatile residual organic matter, are mainly produced by machining, and have high cleanliness requirements, are difficult to detect, and have strict testing environment requirements. Sometimes off-site testing is also required.

[0003] Existing clean detection methods, especially flushing sampling detection methods, have the disadvantages of complex detection methods, inability to perform sampling in confined spaces (such as small boxes with many obstacles), inconvenient carrying of flushing sampling solutions and easy leakage when sampling in other places, possible liquid splashing during sampling, and high requirements for environmental cleanliness. Other detection methods are not accurate, so there is an urgent need for a high-precision NVR clean detection method that can meet the needs of convenient sampling in other places. Summary of the invention

[0004] The purpose of the present invention is to solve the above existing technical problems and provide a non-volatile residue (NVR) clean detection method. The detection method is convenient for sampling, can be used in areas with complex environments, is easy to carry, has high detection accuracy, can meet NVR Class 100 clean detection, and is suitable for convenient sampling in remote locations.

[0005] The technical solution of the present invention is to propose a non-volatile residue (NVR) clean detection method, which mainly implements the accurate measurement of NVR through the steps of sampling, extraction, filtration, baking, weighing and calculation, and specifically includes the following steps:

[0006] S1 Beaker pretreatment: Take two clean beakers A and B and pre-bake them at high temperature, then cool and let them stand, and weigh them using a precision balance to obtain the initial weights of m 1 and m 2 ;

[0007] S2 Background control group preparation: Take a certain amount of clean absorbent cotton, moisten it with methanol solvent, and put it directly into a clean sealed container C without sampling, as the background control group;

[0008] S3 Sampling group preparation: Take clean absorbent cotton of the same mass as in step S2, moisten it with methanol solvent, wipe a certain area of ​​the surface of the workpiece to be tested, and the sampling area is S. After sampling, put it into a clean and sealed container D to complete the sampling, which is the sampling group;

[0009] S4 NVR ultrasonic extraction: add the same volume of methanol solvent as the extractant to the clean sealed container C containing the absorbent cotton obtained in step S2 and the clean sealed container D containing the absorbent cotton obtained in step S3, and then put beakers C and D into an ultrasonic cleaning machine for NVR ultrasonic extraction;

[0010] S5 particle filtration: use a set of clean syringes and needle filters to filter the methanol solutions extracted in the clean sealed container C and the clean sealed container D in step S4 to remove particles, and transfer the filtered solutions into the clean beakers A and B obtained in step S1 respectively;

[0011] S6 Baking and weighing: Place beaker A and beaker B containing methanol solvent obtained in step S5 into a vacuum clean oven for thorough baking, and then weigh them after cooling and standing to obtain the weight m of the background control group and the sampling group. 3 and m 4 ;

[0012] S7 NVR value calculation: NVR of workpiece surface = ((m 4 -m 2 )-(m 3 -m 1 )) / (10S);

[0013] Furthermore, in step S1, the NVR residues in the clean beakers A and B are both less than 0.05 mg, and the vacuum degree of the vacuum clean oven is 10 -1 Pa-10 -3 Pa, the pre-baking temperature is 60°C-70°C, the baking time is 0.5 hour, and the cooling and standing time after pre-baking is 0.5-1 hour; the instrument used for weighing is a precision balance with an accuracy of 0.01mg, the weighing environment is 20°C±3°C, the humidity is (55%±10%)RH, there is no airflow disturbance, the weighing times are 5 times, and the average value is taken;

[0014] Furthermore, in step S2, the clean sealed container C is a clean beaker or a clean plastic cup made of PE material, and in step S3, the clean sealed container D is a clean beaker or a clean plastic cup made of PE material;

[0015] Furthermore, in step S3, the initial weight of the absorbent cotton is 1 g, the NVR residue itself is less than 0.05 mg, and the wiping sampling area S is 0.1 m 2, wipe 3 times along the same direction, the methanol solution level is a gradient level;

[0016] Further, in step S4, the frequency of the ultrasonic cleaning machine is 25KHz-40KHz, the power is 400W-600W, the ultrasonic extraction time is 15-30 minutes, the grade of the methanol solution used as the extractant in the clean sealed containers C and D is a gradient grade, and the volume used is 40ml-50ml;

[0017] Furthermore, in step S5, the NVR of the injection and the syringe filter itself is less than 0.05 mg; the filter membrane of the syringe filter is made of PTFE, and the filter diameter is 0.2 μm;

[0018] Furthermore, in step S6, the vacuum degree of the vacuum clean oven is 10 -1 Pa-10 -3 Pa; the fully baking temperature is 60℃-70℃, the baking time is 2-3 hours, and the cooling and standing time after fully baking is 0.5-1 hour; the instrument used for weighing is a precision balance with an accuracy of 0.01mg, the weighing environment is 20℃±3℃, the humidity is (55%±10%)RH, there is no airflow disturbance, the weighing times are 5 times, and the average value is taken.

[0019] Technical effects of the present invention:

[0020] According to the technical solution of the present invention, sampling can be carried out in a small space (such as a small box with many obstacles). When sampling in a different place, it is easy to carry and does not require a clean environment. Therefore, this detection method can meet the requirements of convenient sampling in different places. At the same time, through the measurement of this detection method, the surface contamination residual data of the blank test is stable, and the final measurement result of NVR is accurate, which can achieve accurate measurement of NVR. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention discloses a flow chart of a non-volatile residue (NVR) clean detection method. DETAILED DESCRIPTION

[0022] The present invention is described in detail below by comparative examples and embodiments, but the protection scope of the present invention should not be limited thereto.

[0023] Embodiment 1:

[0024] This test method is used according to Figure 1 The process of NVR cleanliness testing for a stainless steel surface that has been cleaned is as follows:

[0025] Step 1, take two clean beakers A and beaker B and put them into a clean vacuum oven for pre-baking for 0.5 hours at 60°C and a vacuum degree of 10-3Pa; then cool and stand in a Class 100 clean room at a temperature of 20°C ± 0.5°C and a humidity of (55% ± 5%) RH for 30 minutes, weigh them 5 times using a precision balance with an accuracy of 0.01mg, take the average value, and obtain the initial weights m1 and m2 as 29.23133g and 30.11500g respectively;

[0026] Step 2, take 1 g of clean absorbent cotton, moisten it with gradient grade methanol solvent, and put it into a clean sealed PE plastic cup C as a background control group;

[0027] Step 3: Take 1g of clean absorbent cotton and wet it with gradient methanol solvent. Take 0.1m 2 Area, wipe three times in one direction for NVR sampling, and put it into a clean and sealed PE plastic cup D as a sampling group;

[0028] Step 4, add 40 ml of gradient grade methanol solvent to PE plastic cup C and PE plastic cup D respectively, put them into a cleaning tank, and perform ultrasonic extraction, the ultrasonic frequency is 25KHz, the power is 400W, and the ultrasonic time is 15 minutes;

[0029] Step 5, using a set of clean injection and syringe filters, respectively, to filter the extracted methanol solutions in PE plastic cups C and D to remove particulate matter, and transfer the filtered solutions into clean beakers A and B respectively; the filter membrane material is PTFE, and the filter membrane pore size is 0.2 μm;

[0030] Step 6: Place beaker A and beaker B containing methanol solvent in a clean vacuum oven and bake them thoroughly at 60°C for 2 hours. Then weigh them again in a Class 100 clean room to obtain the weights of the background control group and the sampling group. 3 and m 4 They are 29.23142g and 30.11515g respectively;

[0031] Step 7, using the formula ((m 4 -m 2 )-(m 3 -m 1 )) / (10S) The NVR detection value of the workpiece is calculated to be 0.06mg / 0.1m 2 , less than 0.10mg / 0.1m 2 , proving that the workpiece meets the NVR Class 100 cleanliness requirements.

[0032] Take the detection method of the present invention as an example:

[0033] Randomly select 5 groups of blank test surface contamination residual data ((m 3 -m 1 )) As a comparison, the blank test surface contamination residual data of this detection method is calculated to fluctuate between 0.09mg and 0.18mg, indicating that the detection accuracy is high and it can detect NVR Class 100 cleanliness.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A non-volatile residue (NVR) cleanliness detection method, characterized in that: The precise measurement of NVR is mainly achieved through sampling, extraction, filtration, baking, weighing and calculation, which specifically includes the following steps: S1 Beaker pretreatment: Take two clean beakers A and B and pre-bake them at high temperature, then cool and let them stand, and weigh them using a precision balance to obtain initial weights m1 and m2 respectively; S2 Background control group preparation: Take a certain amount of clean absorbent cotton, moisten it with methanol solvent, and put it directly into a clean sealed container C without sampling, as the background control group; S3 Sampling group preparation: Take clean absorbent cotton of the same mass as in step S2, moisten it with methanol solvent, wipe a certain area of ​​the surface of the workpiece to be tested, and the sampling area is S. After sampling, put it into a clean and sealed container D to complete the sampling, which is the sampling group; S4 NVR ultrasonic extraction: add the same volume of methanol solvent as the extractant to the clean sealed container C containing the absorbent cotton obtained in step S2 and the clean sealed container D containing the absorbent cotton obtained in step S3, and then put beakers C and D into an ultrasonic cleaning machine for NVR ultrasonic extraction; S5 particle filtration: use a set of clean syringes and needle filters to filter the methanol solutions extracted in the clean sealed container C and the clean sealed container D in step S4 to remove particles, and transfer the filtered solutions into the clean beakers A and B obtained in step S1 respectively; S6 baking and weighing: put beaker A and beaker B containing methanol solvent obtained in step S5 into a vacuum clean oven for thorough baking, and then weigh them after cooling and standing to obtain the weights m3 and m4 of the background control group and the sampling group; S7 NVR value calculation: NVR of workpiece surface = ((m4-m2)-(m3-m1)) / (10S).

2. The non-volatile residue cleanliness detection method according to claim 1, characterized in that: In step S1, the NVR residues in the clean beakers A and B are both less than 0.05 mg, and the vacuum degree of the vacuum clean oven is 10 -1 Pa-10 - 3 Pa, the pre-baking temperature is 60℃-70℃, the baking time is 0.5 hour, and the cooling and standing time after pre-baking is 0.5-1 hour; the instrument used for weighing is a precision balance with an accuracy of 0.01mg, the weighing environment is 20℃±3℃, the humidity is (55%±10%)RH, there is no airflow disturbance, the weighing times are 5 times, and the average value is taken.

3. The non-volatile residue cleanliness detection method according to claim 1, characterized in that: In step S2, the clean sealed container C is a clean beaker or a clean plastic cup made of PE material, and in step S3, the clean sealed container D is a clean beaker or a clean plastic cup made of PE material.

4. The non-volatile residue cleanliness detection method according to claim 1, characterized in that: In step S3, the initial weight of the absorbent cotton is 1 g, the NVR residue is less than 0.05 mg, and the wiping sampling area S is 0.1 m 2 , wipe 3 times along the same direction, and the methanol solution level is a gradient level.

5. The non-volatile residue cleanliness detection method according to claim 1, characterized in that: In step S4, the frequency of the ultrasonic cleaning machine is 25KHz-40KHz, the power is 400W-600W, the ultrasonic extraction time is 15-30 minutes, the grade of the methanol solution used as the extractant in the clean closed containers C and D is gradient grade, and the used volume is 40ml-50ml.

6. The non-volatile residue cleanliness detection method according to claim 1, characterized in that: In step S5, the NVR of the injection and the syringe filter itself is less than 0.05 mg; the filter membrane of the syringe filter is made of PTFE, and the filter diameter is 0.2 μm.

7. The non-volatile residue cleanliness detection method according to claim 1, characterized in that: In step S6, the vacuum degree of the vacuum cleaning oven is 10 -1 Pa-10 -3 Pa; the fully baking temperature is 60℃-70℃, the baking time is 2-3 hours, and the cooling and standing time after fully baking is 0.5-1 hour; the instrument used for weighing is a precision balance with an accuracy of 0.01mg, the weighing environment is 20℃±3℃, the humidity is (55%±10%)RH, there is no airflow disturbance, the weighing times are 5 times, and the average value is taken.

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