JPH07260768A - Method for measuring cleaniness of surface of sample - Google Patents

Abstract

PURPOSE:To measure the soil quantitatively in a short time with respect to soil, which can contain many kinds of components not limited to ionicity mate rial. CONSTITUTION:The soil of an object printed board is extracted with mixed liquid of methanol:chloroform:water = 85:10:5 in an extraction vessel 1. The soil of the obtained extracted liquid is concentrated and enriched with a column of SUS 4mm phiX50mm (length), which is filled with octadecyl silane, under the condition of the main-pump flow rate of 0.5ml/min. in a high-speed liquid chromatograph. For the total amount of the obtained enriched soil component, the absorbance of the ultraviolet rays having the wavelength of 275nm is measured with an ultraviolet detector 6. The peak area of the output curve is computed with a data processor 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the cleanliness of a sample surface for evaluating the cleaning of a printed circuit board, press working, mechanical cutting work, other metal working products, or other target samples.

[0002]

2. Description of the Related Art Although chlorofluorocarbon has an excellent cleaning action, its use must be avoided from the viewpoint of environmental protection, and the cleaning process using chlorofluorocarbon has been changed. It became a thing. And while various alternative cleaning agents are being offered one after another, select an appropriate cleaning agent,
And in order to establish a cleaning method, an accurate evaluation of the cleaning results must be carried out.

One of the currently used evaluation methods is visual evaluation under a microscope, and the other is evaluation by the amount of ions by an ion chromatograph. The former can perform a relatively accurate cleaning evaluation, but this has a problem that a difference due to the skill of the person performing the work and an individual difference are inevitable. Further, in the latter case, not all the stains are ionic substances, so in practice, there is often a discrepancy with the visual evaluation, which causes a problem of poor evaluation.

[0004]

SUMMARY OF THE INVENTION The present invention solves the problems of the prior art as described above, and is not limited to ionic substances,
It is an object of the present invention to provide a method for measuring the cleanliness of a sample surface, which can quantitatively measure stains in a short time for stains that may contain various components.

[0005]

However, the gist of the constitution of the present invention is that the stain of the target sample is extracted with an extraction solvent according to the nature of the stain, and the stain of the obtained extract is
In high-performance liquid chromatography, this is a method for measuring the cleanliness of the sample surface by concentrating and concentrating using a column of a length that does not separate the components, and measuring the total amount of the concentrated soil components obtained. The above problems can be solved by.

The extraction solvent differs in the type of the target sample, more specifically, the component of the dirt attached to the target sample, and therefore, an appropriate solvent should be selected and adopted accordingly. For example, it should be determined by considering whether or not the stain contains a polar component, or whether it contains a large proportion, or whether it contains almost no polar component. Most of the stain components can be known by examining the manufacturing process of the target sample.

[0007] For example, when the target sample is a printed circuit board that has been cleaned after soldering, stains attached to it are
In addition to organic acids, which are the main components of flux, it is thought that they are slight cleaning residues of many substances such as finger stains and stains derived from the environment. When a rosin-based flux is used as the flux, it is optimal to use a mixed solution of methanol: chloroform: water = 85: 10: 5 as the extraction solvent. However, this ratio is not limited to this, and depending on the case, a mixed solution having a ratio of methanol: chloroform: water = 50 to 97:30 to 2: 1 to 20 can be used.

If the mixing ratio of chloroform increases, the damage to the substrate usually increases, so the ratio should be adjusted in consideration of this. Water is for the extraction of polar components, and if it is expected that there are many such components, increase this ratio.

Further, for example, if the target sample is a pressed product, a cut product or another metal processed product,
When it is expected that oil such as cutting oil and stains derived from other environments are expected, it is appropriate to use a mixed solution of methanol: chloroform = 1 to 90:10 to 99 as the extraction solvent. is there. Among them, the mixed solution of methanol: chloroform = 6: 4 is most suitable.

The methanol in the above extraction solvent can be replaced with ethanol, and even with this, it is possible to obtain one having substantially the same extraction ability.

By the way, the column used in this measuring method is not for separating the components of the dirt in the extract, but for concentrating and concentrating the components, so that the installation in the device is as short as possible. It is preferably one. For example, it is suitable to construct the column to have a length of about 20 mm to 50 mm.

Ordinary octadecylsilane (ODS) is suitable as a packing material for the column. others,
Octasilane (OS), which has similar properties, can also be used. No other commercially available filler was tested.

As means for measuring the total amount of the concentrated soil component, various devices can be constructed as long as the object can be achieved. An ultraviolet light detector for measuring the absorption of ultraviolet light of the component to be measured, and its detector Suitably it comprises a data processor which counts the area in the closed plane between the output voltage curve and the zero level.

If the stain component is a substance having no or very little absorption of ultraviolet light, it is impossible or inappropriate to use the above ultraviolet light detector.
In such a case, as means for measuring the total amount of the concentrated dirt component, a parallax refractive index detector that measures a parallax caused by a difference in refractive index of a measurement target component, an output voltage curve thereof, and a zero level are used. A data processing device for counting the area in the closed plane is suitable.

[0015]

Therefore, according to the method of the present invention, it is possible to quickly and quantitatively measure the stains on the washed or unwashed sample at low cost. That is, first, for the target sample, the stain can be satisfactorily extracted by using an appropriate extraction solvent according to the property of the stain, as described above.
In a high performance liquid chromatograph, by using a column having a length that does not separate components, for example, a column having a length of 50 mm or less, stains can be obtained in a concentrated state as an aggregate of stains without separating each component. . Therefore, this process can be performed in a very short time of 10 to 20 minutes.

Then, the group of soil components is collectively measured by an appropriate measuring means, for example, the ultraviolet light detector described above. Since it is not meaningful to detect the amount of dirt by separating it from each component, it is intended to detect the dirt as a whole. The detection is in this case carried out on the UV absorption of the dirt component. The detection output of the ultraviolet light detector, that is, the ultraviolet absorption of the stain component is obtained as a voltage value proportional to the absorption ratio of the stain component to the ultraviolet light, and the peak area of the output curve, that is, the output curve and 0. Contamination can be quantified by determining the area in the closed plane between the level.

Therefore, as described above, the stain on the target sample can be easily measured quantitatively at a low cost in a very short time. Furthermore, since the quantitative measurement can be performed as described above, when selecting a washing machine or a washing liquid for a washing target, the washing ability can be effectively evaluated. The sample to be washed is washed with a washing machine or a washing liquid that is a candidate for selection, and then the residual stain of the washed sample is measured by the method of the present invention.
By comparing the measured value with a predetermined reference value, it is possible to evaluate the quality of the selection candidate cleaning machine or cleaning liquid.

The above-mentioned reference value can be determined by, for example, measuring the residual stain on the sample confirmed to be washed to the permissible limit by the method of the present invention, and using the value obtained.

In addition, for example, a standard work to which a fixed amount of a stain standard is attached is prepared in advance for each object to be cleaned, and the result when cleaning this and the result when cleaning an actual work are performed. If the correlation is taken, the standard work is washed with a washing machine or a washing solution that is a candidate for selection, and then the residual stain of the work is measured by the method of the present invention, and the measured value is obtained from the correlation. By comparing with a predetermined permissible reference value, it is possible to evaluate the cleaning machines and cleaning liquids as the selection candidates.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First of all, referring to FIG. 1, an outline of the apparatus used for carrying out the method of the present invention and the operations carried out using this apparatus will be described.

This apparatus comprises an extraction tank 1 for extracting dirt on a target sample, a solvent tank 2 for storing a solvent which is an extraction solution and is also an eluent, an injector valve 4 having a loop 3, a dirt in the extraction solution. A column 5 for concentrating and concentrating water, an ultraviolet light detector 6 for detecting dirt, a data processing device 7 for processing the output of the ultraviolet light detector 6, an extraction tank pump 8 on the side of the extraction tank 1, and a control means. The pump 9 and the drainage tank 10 that stores the drainage liquid are the main components.

First, the initial state of the apparatus is started up as follows. When the device is operated, first, the valve 1 arranged between the extraction tank 1, the solvent tank 2 and the extraction tank pump 8 is
1 is switched, and the solvent tank 2 by the extraction tank pump 8
The extraction liquid is pumped up from and is supplied to the extraction tank 1 via the loop 3 of the injector valve 4 and the valve 12. When a predetermined amount of extraction liquid is supplied to the extraction tank 1, this process is completed, the valve 11 is switched, and the valve 11, the extraction tank pump 8, the loop 3 of the injector valve 4 and the extraction tank 1 are connected. The initial state is repeated in which the circulation returning to the extraction tank 1 via the valve 12 is repeated.

Next, when the target sample is immersed in the extraction tank 1 to start the dirt measuring operation, first, in the extraction tank 1,
The stirrer 13 attached to this operates to stir the extraction liquid in the extraction tank 1 to average the concentration and extract the stains of the target sample. The extracted dirt circulates in the circulation process of passing through the loop 3 and the like of the injector valve 4 by the extraction liquid. The above extraction operation takes 3 minutes to 5 depending on the target sample.
A minute or so is done.

On the other hand, the main pump 9 starts operating when the dirt measuring operation starts, the eluent is pumped up from the solvent tank 2, introduced into the column 5 through the injector valve 4, and further the ultraviolet light detector. After being introduced into the drainage tank 6, the drainage is discharged to the drainage tank 10. In this way, it stands by for the introduction of the extract.

After the elapse of a predetermined extraction time, the injector valve 4 is switched in response to the start signal output from the arithmetic unit of the main pump 9, and the dirty extract liquid circulating in the loop 3 is transferred to the column 5. It is pumped and the components of the dirt are concentrated and concentrated in the column 5. That is, the column 5 is 20 mm
It is configured to be sufficiently short to about 50 mm, so that the components of dirt are not concentrated and spread, but are concentrated and concentrated.

Next, the concentrated and concentrated dirt component is introduced into the ultraviolet light detector 6 together with the eluent, and the absorbance of the ultraviolet light is detected. Then, the detection signal is output as a voltage value proportional to the absorbance of the stain component, is input to the data processing device 7 in the next stage, and a voltage output curve based on the stain component is output, and one or more of the output curves is output. The peak area based on the peaks of, i.e., the area in the closed plane between the output curve and the 0 level is calculated. Thus, the stain is quantified.

The extract passed through the ultraviolet light detector 6 is discharged to the drain tank 10 as drain.

On the other hand, when the start signal is received from the arithmetic unit of the main pump 9, the residual liquid discharge and cleaning operation of the extraction tank 1 is started at the same time as the above dirt detection operation.
That is, the valve 12 is switched, and the residual liquid in the extraction tank 1 is discharged to the drainage tank 10 by the extraction tank pump 8 via the valve 11, the extraction tank pump 8, the injector valve 4 and the valve 12. .

When the drainage discharge operation is completed, the valves 11 and 12 are switched at the same time,
The extraction tank pump 8 pumps up the extraction liquid from the solvent tank 2 and supplies it to the extraction tank 1 via the valve 11, the extraction tank pump 8, the injector valve 4 and the valve 12. When a predetermined amount of the extraction liquid is supplied to the extraction tank 1, the stirrer 13 operates to stir and wash the inside of the extraction tank 1. After the stirring and washing operation for a predetermined time, the valve 11 and the valve 12 are switched at the same time, and the extraction pump 8 discharges the drained liquid through the valve 11, the extraction tank pump 8, the injector valve 4 and the valve 12 as described above. The liquid is discharged via the drainage tank 10. This process is repeated again, and then the initial state is restored.

Example 1 In this example, after cleaning the board which has undergone the soldering process performed under the same conditions with four kinds of cleaning agents, the residual dirt was measured using the apparatus of the above-mentioned example. Is. Sample to be measured Sample 1 ... Substrate washed with Freon (113). Sample 2 ... Substrate washed with non-aqueous cleaning agent (Techno Care FRW-16: trademark of Toshiba Corporation) Sample 3 ... Substrate washed with alternative cleaning agent (Asahi Kulin AK-225: trademark of Asahi Glass Co., Ltd.) Sample 4 ... Substrate washed with alternative cleaning agent (Asahi Klin AK-225U: trademark of Asahi Glass Co., Ltd.)

Instrument conditions Eluent / extractant: Methanol: chloroform: water =
85: 10: 5 Main pump flow rate: 0.5 ml / min Column: SUS4mmφ × 50mm, packing material:
Octadecylsilane UV photodetector ... 275 nm (wavelength) Data processing device ... Integrator The above-mentioned device conditions were set for the above device, and the measurement operation was performed on Samples 1 to 4 as described above. It should be noted that the extraction time of the residual dirt on the sample is 5 minutes, and the time for the concentrated concentration and detection operation of the extracted dirt after the column is 10 minutes.

The voltage output curves of the data processor are shown in FIGS.
As shown in FIG. 5, FIG. 2 shows the output for sample 1, FIG. 3 shows the output for sample 3, FIG. 4 shows the output for sample 3, and FIG. 5 shows the output for sample 4, respectively. .

Further, the peak area of the output curve of each of the above samples (the area within the closed plane surrounded by the output curve and 0 level)
Is as shown in Table 1 below.

[0034]

[Table 1] Peak area Sample name Peak area value Sample 1 3,133 Sample 2 6,550 Sample 3 30,130 Sample 4 10,2318

The above peak areas are further graphed as shown in Table 2 below.

[0036]

[Table 2]

As a comparative example to the above Example 1, the same samples 1, 2, 3 and 4 were evaluated for the amount of ions by ion chromatography. The results are shown in Table 3.

[0038]

[Table 3]

At the same time, the same samples 1, 2, 3 and 4 were evaluated by visual observation under a microscope. The results are shown in Table 4 below.

[0040]

[Table 4] Visual evaluation under microscope Sample name Evaluation sample 1 Good sample 2 Good sample 3 Bad sample 4 Bad

Therefore, in Example 1, if the peak area of 10,000 is evaluated as an acceptable reference value, Example 1
Also, in the visual evaluation under the microscope, Samples 1 and 2 are “good”, and Samples 3 and 4 are “poor”, which are in good agreement. And this result is in full agreement with the conclusion at the manufacturing site. Further, when the residual stains of Example 1 and Samples 3 and 4 which were judged to be defective by visual evaluation under a microscope were measured by an infrared microscope, a spectrum considered to be an organic acid derived from the flux was detected.

On the other hand, the measurement result of the amount of ions by the ion chromatograph given as a comparative example shows that Sample 3 can be clearly evaluated as defective, but Samples 1, 2 and 4 are distinguished. hard. This is the reason why it is not possible to draw conclusions from the measurement results alone at the manufacturing site.

Example 2 In this example, the residual dirt was measured using the apparatus of the above-mentioned example, for an unwashed product of a pressed metal work and a washed product which was dipped and washed with methylene chloride at different immersion times. It was done. That is, this is an example of measurement of the residual oil content. Sample to be measured Sample 5: Unwashed product of pressed metal work Sample 6: Immersion washed product of pressed metal work with methylene chloride for 3 seconds (room temperature) Sample 7: With methylene chloride of pressed metal work Immersion washed product for 30 seconds (room temperature)

Equipment conditions Eluent / extractant: methanol: chloroform = 6:
4 Main pump flow rate: 0.5 ml / min column: SUS4mmφ × 50mm, packing material:
Octadecylsilane UV photodetector ... 275 nm (wavelength) Data processing device ... Integrator The above-mentioned device conditions were adjusted, and the measurement operation was performed on Samples 5 to 7 as described above. The extraction time of the residual dirt of the sample is 5 minutes, and the operation time of concentrated concentration and detection operation of the extracted dirt after the column is 8 minutes.

The voltage output curve of the data processor is shown in FIG.
As shown in FIG. 8, FIG. 6 shows the output for sample 5, FIG. 7 shows the output for sample 6, and FIG. 8 shows the output for sample 7.

Furthermore, the peak area of the output curve of each of the above-mentioned samples (the area within the closed plane surrounded by the output curve and the 0 level)
Is as shown in Table 5 below.

[0047]

[Table 5] Peak area Sample name Peak area value Sample 5 1,967,824 Sample 6 189,792 Sample 7 21,041

The above peak areas are further graphed as shown in Table 6 below.

[0049]

[Table 6]

As described above, it is clear that a large amount of dirt (press oil) is attached to the unwashed sample 5, and the sample 6 washed for 3 seconds and the sample 7 washed for 30 seconds are clearly seen. A clear difference is also detected. Contamination is about 1/10 of the sample 6 washed for 3 seconds compared with the unwashed sample 5 and 1/94 of the sample 7 washed for 30 seconds compared with the sample 5 for another 3 seconds. It can be seen that it is about 1/9 as compared with the washed sample 6. And such a result shows that the allowable reference value is 200,0.
Samples 6 and 7 are good when placed at 00, which is in agreement with the visual evaluation under the microscope and the evaluation at the manufacturing site.

Therefore, as described above, the present invention can be favorably applied to an object such as a machined product which is presumed to have oil stains.

[0052]

According to the method for measuring the cleanliness of the sample surface of the present invention, the stains on the sample surface can be treated in a short time and at a low cost without distinguishing whether the stains are ionic or nonionic. Therefore, it can be quantitatively measured. Therefore, if this cleanliness measuring method is used, it is possible to accurately evaluate the cleaning of various target articles, and it is possible to contribute to selecting an appropriate cleaning agent and establishing the cleaning method.

[Brief description of drawings]

FIG. 1 is a system flow diagram for implementing the present invention.

2 is an output curve diagram showing the output of Sample 1 of Example 1. FIG.

FIG. 3 is an output curve diagram showing the output of Sample 2 of Example 1.

FIG. 4 is an output curve diagram showing the output of Sample 3 of Example 1.

5 is an output curve diagram showing the output for Sample 4 of Example 1. FIG.

6 is an output curve diagram showing the output of Sample 5 of Example 2. FIG.

7 is an output curve diagram showing the output of Sample 6 of Example 2. FIG.

8 is an output curve diagram showing the output of Sample 7 of Example 2. FIG.

[Explanation of symbols]

 1 Extraction Tank 2 Solvent Tank 3 Loop 4 Injector Valve 5 Column 6 Ultraviolet Light Detector 7 Data Processing Device 8 Extraction Tank Pump 9 Main Pump 10 Drainage Tank 11 Valve 12 Valve 13 Stirrer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Takahagi 3781-1 Nagaokaya, Ibaraki-cho, Higashi-Ibaraki-gun, Ibaraki 3781-1 Industrial Technology Center, Ibaraki (72) Inventor Toshiyuki Asano 3781 Nagaoka-ya, Ibaraki, Ibaraki-gun, Ibaraki- 1 Inside the Ibaraki Prefectural Industrial Technology Center

Claims (10)

[Claims] 1. A stain of an object sample is extracted with an extraction solvent according to the nature of the stain, and the stain of the obtained extract is used in a high performance liquid chromatograph using a column of a length that does not separate the components. A method for measuring the cleanliness of a sample surface by concentrating and concentrating and measuring the total amount of the obtained concentrated soil components. 2. When the target sample is a printed circuit board, the extraction solvent is methanol: chloroform:
The method for measuring cleanliness of a sample surface according to claim 1, wherein a mixed solution of water = 50 to 97:30 to 2: 1 to 20 is used. 3. When the target sample is a metal processed product,
As the extraction solvent, methanol: chloroform = 1 to
A mixed solution of 90:10 to 99 is used.
Method for measuring cleanliness of sample surface. 4. When the target sample is a printed circuit board, the extraction solvent is ethanol: chloroform:
The method for measuring cleanliness of a sample surface according to claim 1, wherein a mixed solution of water = 85: 10: 5 is used. 5. When the target sample is a metal processed product,
As the extraction solvent, ethanol: chloroform = 6:
The method for measuring the cleanliness of the sample surface according to claim 1, wherein the mixed solution of 4 is used. 6. The method for measuring the cleanliness of the sample surface according to claim 1, wherein the column has a length of 20 mm to 50 mm. 7. The method for measuring cleanliness of a sample surface according to claim 1, wherein octadecylsilane is used as a packing material for the column. 8. The method for measuring cleanliness of a sample surface according to claim 1, 2, 3, 4, 5, or 6, wherein octasilane is used as a packing material for the column. 9. An ultraviolet photodetector for measuring the ultraviolet light absorption of a component to be measured, and a closed plane between the output voltage curve and the 0 level, as means for measuring the total amount of the concentrated stain component. 9. A method for measuring cleanliness of a sample surface according to claim 1, 2, 3, 4, 5, 6, 7, or 8, which comprises a data processing device for counting the area inside. 10. A parallax refractive index detector that measures a parallax caused by a difference in refractive index of a measurement target component as a means for measuring the total amount of the concentrated dirt component, and an output voltage curve between the parallax refractive index detector and the 0 level. A data processing device for counting the area in a closed plane.
7 or 8 The measuring method of the cleanliness of the sample surface.