KR100668787B1 - Particle sampler for sampling particulate contaminants from inside of hard disk drive, and performance valuation device of the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particle sampler for collecting particulate contaminants generated inside a hard disk drive and an apparatus for evaluating the performance of the particle sampler. Collected and sampled particles can be analyzed with an electron microscope and OJ electron spectrometer without any additional work.

Particle sampler according to the present invention for this purpose has a cylindrical shape penetrating the upper and lower parts and the discharge portion is formed on the side and forming a positive electrode; An inlet pipe having a nozzle installed at an inner diameter of the upper portion of the body part and introducing particles contained in sampling air inside the hard disk drive to be discharged into the body part through the nozzle; An electrode installed at an inner diameter of the lower part of the body part, the electrode having a detachable sampling substrate for collecting particles introduced into the body part and transmitting a negative electrode to the sampling substrate; A discharge pipe installed at an outlet of the body and discharging particles not collected on the sampling substrate to the outside; A bottom cover installed at an inner diameter of the lower portion of the body part and configured of a non-conductive material to fix the electrode by inserting it in one direction into a hole formed at a center thereof; And a screw for fastening and fixing the electrode protruding to the other side of the bottom cover and supplying power to the electrode.

Particles, samplers, hard disk drives, contaminants, sampling boards

Description

PARTICLE SAMPLER FOR SAMPLING PARTICULATE CONTAMINANTS FROM INSIDE OF HARD DISK DRIVE, AND PERFORMANCE VALUATION DEVICE OF THE SAME}

1 is a block diagram of a particle sampler for collecting particulate contaminants generated inside the hard disk drive according to the present invention.

2A and 2B are cross-sectional and dimensional views of a particle sampler for collecting particulate contaminants generated inside a hard disk drive according to the present invention.

3 is an experimental apparatus for the performance evaluation of the particle sampler for collecting particulate contaminants generated in the hard disk drive according to the present invention.

Figure 4a is a graph of the performance evaluation of the particle sampler according to the invention when the sampling flow rate using the experimental apparatus for the performance evaluation of Figure 3 is 0.3 lpm

Figure 4b is a graph of the performance evaluation of the particle sampler according to the invention when the sampling flow rate using the experimental apparatus for the performance evaluation of Figure 3 1.5 lpm

5 is an experimental apparatus for evaluation of particle collection performance of the particle sampler for collecting particulate contaminants generated inside the hard disk drive according to the present invention.

FIG. 6A is a graph illustrating performance evaluation results of collection efficiency obtained by collecting particles generated in an actual hard disk drive at 0.3 lpm using a particle sampler for collecting particulate contaminants generated in a hard disk drive according to the present invention.

6b is a graph illustrating performance evaluation results of collection efficiency obtained by collecting particles generated in an actual hard disk drive at 1.5 lpm using a particle sampler for collecting particulate contaminants generated in a hard disk drive according to the present invention.

FIG. 7A is an enlarged photograph of a contaminant attached to a slider surface in a hard disk drive using an electron microscope

FIG. 7B is a graph illustrating analysis of contaminants in FIG. 7A using OJ electron spectroscopy. FIG.

FIG. 8A is an enlarged photograph taken of contaminants attached to another slider surface in a hard disk drive using an electron microscope

FIG. 8B is a graph illustrating analysis of contaminants in FIG. 8A using OJ electron spectroscopy. FIG.

Figure 9a is an enlarged photograph of the particulate contaminants generated in the hard disk drive according to the present invention

9B is a graph showing the results of component analysis of OJ electron spectroscopy on particulate contaminants attached to the sampling substrate of the present invention.

10 is an experimental apparatus for analyzing the size of particulate contaminants generated by a change in the number of revolutions of the disk inside the hard disk drive using the present invention

11A to 11D are enlarged photographs of the particulate contaminants generated inside the hard disk drive collected on the sampling substrate of the particle sampler at 2700, 5400, 7200, and 9600 rpm, respectively.

<Description of Major Symbols in Drawing>

10: particle sampler 11: body

12: inlet pipe 13: nozzle (nozzle)

14 discharge pipe 15 electrode

16: Sampling plate

17: Bottom cover

18: screw 19: washer

20 clean air supply system 21 spray atomizer

22: moisture remover 23: filter

24: diffusion dryer 25: neutralizer

26: differential mobility analyzer (DMA)

27 dilution chamber

28, 55: needle valve

29: rotameter

30, 44: condensation particle sizer (CPC)

31, 54: power supply

41, 51: motor control computer 42, 52: filter

43, 53: HDD (CSS-type) 45: power supply

56: vacuum pump

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particle sampler for capturing particulate contaminants generated in a hard disk drive and a performance evaluation device for the particle sampler. Particularly, the present invention relates to a particle sampler regardless of the size of particulate matter generated in a hard disk drive. The present invention relates to a particle sampler for collecting particulate contaminants generated in a hard disk drive that can collect and sample the sampled particles with an electron microscope, an ozone electron spectrometer, and the like, without additional work.

Today, hard disk drives (HDDs) are becoming increasingly important for reliability as their storage capacity and storage density increase dramatically every year. One of the decisive factors in the reliability of hard disk drives is particle contamination. In order to increase the storage capacity of the hard disk, it is necessary to reduce the slider's flying height in the Head Disk Interface (HDI), which has recently been reduced to a few nm by the height between the slider and the disk. Particles are generated while phenomena such as scratching or surface deformation occur. Particles can also be introduced internally during the assembly of the hard disk drive. These particles move along with the flow of air and stick to the surface of the disk, or collide with or attach to the head, causing heat to instantly generate heat in the slider, causing data loss in the magneto resistive sensor. (thermal asperity). Therefore, characterizing the particles generated inside the hard disk drive is an essential part of particle contamination reduction.

The method of analyzing particles uses various equipment such as Scanning Electron Microscopy (SEM), Auger Electron Spectroscopy (AES), and so on. It is impossible to analyze. Therefore, specimens should be prepared using an indirect sampling method and transferred to a measuring device for qualitative or quantitative analysis.

There are several kinds of methods for sampling particles. First, an impactor is used, which is mainly used to measure the concentration of fine particles in the atmosphere. Currently, the sampling method using the impactor is mainly designed to measure the number of particles in the atmosphere or soot in real time. Therefore, the sampling flow rate is large, and the volume of the device itself is large. Therefore, when the sampled particles are separated and analyzed by using a precision measuring device such as an electron microscope or an OJ spectrometer, the collected particulate matter requires additional work, which is not suitable for the application. Another sampling method is a particle collection method using a filter. A fiber filter or a membrane filter is used according to sampling characteristics. This method can sample the particles in a relatively simple way, but problems such as pressure drop or the possibility of damage to the filter occur during sampling, and when the precision analyzer is to be analyzed, it is cut to fit the specified specimen size. Additional work is required, such as the loss or damage of the sampled particles during the work.

In order to compensate for these problems, a sampler adopting an electrostatic precipitating method has been researched and manufactured in the past. However, since the particles to be sampled are mainly particles in the atmosphere, they are manufactured based on sufficient particle concentrations, and an additional particle charging part such as a charger is required. In addition, for the sampling of particulate matter generated inside the hard disk drive, since the particles are generated inside the hard disk drive, the concentration of particles generated is very small, so that the loss of particles during sampling should be minimized. The area where particles are collected should be minimized.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to collect micro and sub micro sized particulate matter generated in a hard disk drive at low flow rate without loss and to collect sampled particles without additional work. The present invention provides a particle sampler for collecting particulate contaminants generated inside a hard disk drive that can be analyzed by a microscope, an OJ electron spectrometer, and the like, and an apparatus for evaluating the performance of the particle sampler.

Particle sampler according to the present invention for achieving the above object has a cylindrical shape penetrating the upper and lower parts and the discharge portion is formed on the side and forming a positive electrode; An inlet pipe having a nozzle installed at an inner diameter of the upper portion of the body part and introducing particles contained in sampling air inside the hard disk drive to be discharged into the body part through the nozzle; An electrode installed at an inner diameter of the lower part of the body part, the electrode having a sampling substrate for collecting particles introduced into the body part and forming a negative electrode; A discharge pipe installed at an outlet of the body and discharging particles not collected on the sampling substrate to the outside; A bottom cover installed at an inner diameter of the lower portion of the body part and configured of a non-conductive material to fix the electrode by inserting it in one direction into a hole formed at a center thereof; And a screw for fastening and fixing the electrode protruding to the other side of the bottom cover and supplying power to the electrode.

Here, the inlet pipe, the discharge pipe, the electrode, the body portion is characterized in that composed of a conductive material.

In addition, the sampling substrate is characterized by using any one of a thin aluminum, copper substrate, conductive substrate.

In addition, the sampling substrate is characterized in that the diameter is the same as or larger than the diameter of the electrode.

In addition, the sampling substrate is characterized in that the detachable from the electrode.

In addition, the inlet pipe, the discharge pipe and the bottom cover is characterized in that the detachable to the body portion.

In addition, the particle sampler, the particles of the submicron region of less than 1㎛ among the particles collected on the sampling substrate is mostly collected by the electric field, the particles of the micron region of more than 1㎛ are mostly collected by the inertial force of the particles It is done.

Performance evaluation device of the particle sampler for achieving the above object comprises a clean air supply system for filtering the particles and water contained in the air to make a clean state and then discharged into compressed air; A spray particle generator configured to discharge the compressed air from the clean air supply system into a particulate state at a high pressure and a high velocity state; A water remover and a diffusion dryer for removing water contained in the particles discharged from the spray particle generator; A neutralizer for making particles discharged from the diffusion dryer into a Boltzmann charging equilibrium; An electrical mobility analyzer (DMA) for selectively generating particles of various particle sizes discharged from the neutralizer into particles of a single particle size of a desired size by an electrical method; A dilution tube for diluting the concentration of particles of a single particle diameter discharged from the DMA; A particle sampler which injects and collects particles discharged from the dilution tube, wherein the particles of the submicron region are collected by an electric field, and the particles of the micron region are collected by the inertial force of the particles; A condensation nucleus counter that measures the sampling efficiency by injecting particles not collected in the particle sampler; And a power supply for supplying an electric field to the particle sampler.

Herein, the particle sampler may have a cylindrical shape having upper and lower portions penetrated therein and a discharge portion formed at a side thereof to form a positive electrode; An inlet pipe having a nozzle installed at an inner diameter of the upper portion of the body part and introducing particles contained in sampling air inside the hard disk drive to be discharged into the body part through the nozzle; An electrode installed at an inner diameter of the lower part of the body part, the electrode having a sampling substrate for collecting particles introduced into the body part and forming a negative electrode; A discharge pipe installed at an outlet of the body and discharging particles not collected on the sampling substrate to the outside; A bottom cover installed at an inner diameter of the lower portion of the body part and configured of a non-conductive material to fix the electrode by inserting it in one direction into a hole formed at a center thereof; And a screw for fastening and fixing the electrode protruding to the other side of the bottom cover and supplying power to the electrode.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

1 is a block diagram of a particle sampler 10 for collecting particulate contaminants generated in the hard disk drive according to the present invention, and FIGS. 2A and 2B illustrate particulate contaminants generated in the hard disk drive according to the present invention. A cross sectional and dimensional view of a particle sampler for collection.

As shown in FIGS. 1 and 2A, the particle sampler 10 may include a body part 11, an inlet pipe 12, a nozzle 13, an outlet pipe 14, an electrode 15, and a sampling substrate. (sampling plate) 16, bottom cover 17, screws 18, washers 19 and the like.

Here, the body portion 11 is formed of a cylindrical conductive material penetrating the upper and lower portions, the outlet 11a for installing the discharge pipe 14 is formed on the side and the power supply from the power supply (not shown) It is supplied to form a positive electrode.

In addition, the inlet pipe 12 is provided with a nozzle 13 on one side, the nozzle 13 is configured to be installed in the inner diameter of the upper portion of the body portion 11, as shown in FIG. Accordingly, the inlet pipe 12 introduces particles contained in sampling air inside the hard disk drive and discharges the particles into the body through the nozzle 13.

In addition, the electrode 15 is installed at the inner diameter of the lower portion of the body portion 11 by the bottom cover 17, and collects particles introduced into the body portion 11 through the nozzle 13. A sampling substrate 16 is provided on one side. Here, the method of fixing the electrode 15 to the bottom cover 17, as shown in Figs. 1 and 2a, after inserting the electrode 15 in the hole formed in the center of the bottom cover 17 The washer 19 is inserted into the electrode 15 protruding from the opposite side of the bottom cover 17 and then fixed by fastening with a screw 18. At this time, the bottom cover 17 is installed in the inner diameter of the lower portion of the body portion 11 is made of a non-conductive material to insert the electrode through a hole formed in the center and then to fix the electrode with a screw.

In addition, the electrode 15 is made of a conductive material and receives a power from a power supply (not shown) to form a negative (-) electrode.

The discharge pipe 14 is installed in the discharge port 11a of the body portion 11 and discharges particles inside the body portion 11 that are not collected by the sampling substrate 16 to the outside.

As shown in FIG. 2A, particles included in sampling air are introduced into the body part 11 through the inlet pipe 12 and through the nozzle 13 therein. At this time, some of the introduced particles are collected on the sampling substrate 16, and the remaining uncollected particles are discharged to the outside of the sampler through the discharge pipe 14.

The size of the particle sampler will be described with reference to FIG. 2B as an example. That is, as shown in FIG. 2B, the diameter D _R of the body portion 11 is 18 mm, the diameter D _O of the inlet pipe 12 and the discharge pipe 14 is 6 mm, and the electrode 15 The diameter D _W is 7.6 mm, the diameter W of the nozzle 13 is 0.49 mm, and the distance S between the electrode 15 and the nozzle 13 is 0.8 mm.

Looking at the material of each part of the sampler, the inlet pipe 12, the discharge pipe 14, the electrode 15 is made of aluminum (Al) material, from the power supply (not shown) (+) or ( Power was supplied to collect the charged particles on the sampling substrate 16 by electrical force. The sampling substrate 16 may use a thin aluminum, copper substrate, or a conductive substrate, and the body portion 11, the inlet pipe 12, the discharge pipe 14, and the electrode 15 may also use a conductive material. Can be.

The body portion 11 of the sampler serves as the ground by using the same aluminum (Al) or conductive material as the inflow pipe 12, the discharge pipe 14, and the electrode 15. The bottom cover 17 portion was selected from a non-conductive plastic material so as not to conduct electricity. The bottom cover 17 was fastened with screws 18 to fix the electrode 15 and the bottom cover 17 and to supply a power supply.

The following is a description of the performance evaluation of the particle sampler for collecting particulate contaminants generated in the hard disk drive of the present invention.

Experimental factors affecting the collection efficiency of the particle sampler fabricated for this experiment include sampling flow rate and particle size, externally applied electric field strength, and particle charge amount. However, in the case of the charged amount of the particles, the charge amount is changed according to the size of the particles when charged through a charge (charger), in this experiment, the performance evaluation for the same charge amount. However, the sampling flow rate and particle size varied, and the change in sampling efficiency was measured.

An experimental apparatus for evaluating the performance of the particle sampler 10 is shown in FIG. 3.

As shown in FIG. 3, the experimental apparatus includes a clean air supply system 20, an atomizer 21, a water trap 22, a filter 23, and a diffusion dryer. (24), neutralizer (Kr85) (25), differential mobility analyzer (DMA) (26), dilution chamber (27), needle valve (28), A rotameter 29, a condensation particle sizer (CPC) 30, a power supply 31, and the like.

The compressed air passing through the clean air supply system 20 is filtered to particles or moisture contained in the air and supplied to the spray particle generator 21 in a clean state. The spray particle generator 21 contains a mixture of sodium chloride (NaCl) and distilled water or a mixture of dioctylsebacate (DOS) particles and an alcohol, and clean air is used to form an orifice inside the spray particle generator 21. It is sprayed on the inner wall at high pressure / high speed while passing through orifice. At this time, the sprayed mixed solution is broken into very small particles while strongly impacting the inner wall of the spray particle generator 21, and is discharged to the outside of the container by high pressure. As such, the particles generated in the spray particle generator 21 pass through the water remover 22 and the diffusion dryer 24 to remove moisture, and the particles pass through the neutralizer 25 again, and the Boltzmann charging equilibrium ( Boltzmann charge equilibrium) is supplied to the electrical mobility analyzer (DMA) 26.

The electrical mobility analyzer (DMA) 26 serves to selectively generate particles of various particle sizes generated by the spray particle generator 21 into particles of a single particle size of a desired size by an electrical method. When discharged to the outside of the device, the charge amount is made equal to (+) monovalent state. As such, the particles having a single particle diameter selected and generated are injected into the particle sampler 10 while the concentration is diluted while passing through the dilution tube 27. In this case, the particles not collected by the particle sampler 10 are discharged to the outside of the particle sampler 10 and finally injected into the condensation nucleus counter (CPC) 30 to measure the number. At this time, the sampling efficiency measurement was calculated with the concentration of particles when the sample was bypassed by the direct condensation nucleus counter without passing through the particle sampler and the measured concentration data of the particles after passing through the sampler.

Performance evaluation of the particle sampler 10 was performed in two modes, 0.3 lpm and 1.5 lpm, which are inherent sampling flow rates of the condensation nucleus counter 30, and the results are shown in FIGS. 4A and 4B. The same particle size range was measured from 50 nm to 400 nm at both flow rates, with 50 nm to 150 nm particles using NaCl and 150 nm to 400 nm particles using dioctyl sebacart particles. The voltage applied from outside also changed the same from 0 kV to 0.5 kV.

First, referring to FIG. 4A, it can be seen that the particle size and the sampling efficiency are inversely related, and that the external applied voltage and the sampling efficiency are proportional to each other. This result is similar to that of an electrostatic precipitator (ESP). The trend is similar to the dust collection efficiency. Therefore, in FIG. 4B, the results are similar to those of FIG. 4A in the particle size region of 200 nm or less, but the overall efficiency is decreased. This is considered to occur because the residence time of the particles is shortened due to the increase in the flow rate inside the sampler. However, it can be observed that the sampling efficiency, which decreased in the particle size of 200 nm or more, is rapidly increased. This phenomenon occurs because the cross-sectional velocity at the nozzle is increased due to the increase in the flow rate inside the sampler. Assuming that the particle sampler is an impactor of a single particle size, the formula for a 50% efficient cut diameter (d ₅₀ ) is as follows.

는 공기의 점성계수, W는 노즐직경,

은 분리입경에서의 스톡스 수(Stoke’s number),

는 입경에 대한 미끄럼 보정계수(Cunningham correction factor),

는 입자의 밀도, 그리고 U는 노즐목에서의 평균유속이다. 이와 같이 정의된 수학식 1에 샘플러의 치수 및 실험조건에 해당하는 값들을 대입하여 계산한 결과를 표 1에 나타내었다.here,

Is the viscosity of air, W is the nozzle diameter,

Is the Stokes' number at the separation particle,

Is the sliding correction factor for the particle size,

Where is the particle density, and U is the average velocity at the nozzle neck. Table 1 shows the results obtained by substituting the values corresponding to the size and experimental conditions of the sampler in Equation 1 defined above.

d _{A, 50} d _{Nacl, 50} d _{DOS, 50} 1.3 lpm 710 nm 478 nm 742 nm 1.5 lpm 300 nm 202 nm 313 nm

First, d _A , ₅₀ is the aerodynamic separation of particles with a unit density assumed to be perfectly spherical, and d _{NaCl, 50} is the separation for NaCl particles (ρ _NaCl : 2.2 g / cm ³ ). Particle diameter, d _{DOS, 50} is the separation particle size for dioctyl sebacart (DOS) particles (ρ _DOS : 9.125 g / cm ³ ). Here, when the flow rate is about 313 nm when the separation particle size of the DOS particles in the 1.5 lpm condition, it shows a collection efficiency of about 48% when the particle size of 300 nm in Figure 4b. As a result, the size of 200 nm or more of the DOS particles in the sampler is captured by the inertial force of the particles, as well as the impactor, and it can be seen that they are hardly influenced by an externally applied electric field.

The particle sampler 10 collects most of the submicron particles (<1 μm) of the particles to be sampled under the influence of an electric field applied outside the sampler, and also submicron particles close to microns and particles in the micron region (>). 1 μm) are intended to be collected by inertial impaction.

To summarize the facts that can be known through the performance evaluation of the particle sampler 10 is as follows. Most of the nanoparticles with a relatively low flow rate (0.3 lpm) passing through the nozzle inside the sampler were collected by an electric field applied from the outside, and showed a collection efficiency of 90% or more when the particle size was 50 nm. If the flow rate is increased (1.5 lpm), the particle area collected by the electric field is reduced, the area collected by inertia increases, and the particles in the micron area show more than 90% of the collection efficiency. Therefore, when the particle sampler is used, the particles are collected by the electric field when the particles in the submicron region (<1 μm) are collected, and the collection efficiency is at least 90%. When the particles in the micron region (> 1㎛) were collected, the particles were collected by the inertial force of the particles, and the collection efficiency showed up to 90% or more.

Example 1

The particle sampler 10 for collecting particulate contaminants generated in the hard disk drive according to the present invention is used to collect particles generated in the actual hard disk drive to measure collection efficiency, and to collect the sampling substrate 16 from the particles. The particles separated from the sampler 10 and attached to the surface were subjected to component analysis using an OJ electron spectrometer.

Experiments using a particle sampler for characterization of particles generated inside the hard disk drive were conducted in a class 100 clean booth to prevent contamination from air and indoor fine dust. The hard disk drive uses a two-disk four-head type of contact start / stop (CSS) method designed for a rotational speed of 5400 rpm, and the slider is dragged to rotate in contact with the disk without completely injuring the slider. A certain load was applied to the slider to create a Drag condition. This is to increase the number of abrasive particles generated when the hard disk drive. 5 is an experimental apparatus diagram for the present experiment, which is divided into two parts, a device for sampling particles and a device for separating and analyzing sampled particles.

First, the experimental apparatus for particle sampling, the air injected through the clean air supply is passed through the filter 42 to remove the external particles once again is supplied to the hard disk drive. In order to efficiently sample the generated particles, two jet nozzles were installed on the cover of the hard disk drive to inject air from the outside at a high speed. At this time, the supply flow rate was 2 lpm, and the speed of the air jet injected from each jet nozzle was about 16.7 kPa. Here, the flow rate required for sampling is 0.3 lpm or 1.5 lpm, and for the remaining flow rate, excess air outlet is made in the hard disk drive cover and discharged to the outside. Here, the particles discharged to the sampling tube is moved to the particle sampler 10, an electric field is formed in the particle sampler 10 to which a voltage is applied from the power supply 45, and the sampling substrate ( In 16) particles are collected. Here, in order for a particle to be sampled by an electric force, the particle itself must have a constant number of charges. In general, particulate matters generated inside the hard disk drive are generated by friction of a slider-disk and are charged with a constant number of charges. As such, there is no need for additional particle charge parts. As mentioned earlier, the trapped particles adhere to the substrate, but the uncollected particles flow out of the sampler along the original flow and are drawn into the condensation nucleus counter.

Particles sampled in the above way are separated from the sampling substrate and analyzed according to the purpose of use in another analysis device. In this experiment, the slider-disk interface and the sampled particles after the sampling experiments were observed for the approximate size and shape through electron microscopy images, and the components were analyzed by OJ electron spectroscopy.

6A and 6B are graphs of collecting efficiency by sampling particles generated when an actual hard disk drive is driven. In the sampling efficiency measurement, the flow rate was separated into FIGS. 6A and 6B according to the change of the flow rate, and the disk rotation speed and the applied voltage were changed. As a result, it was observed in both FIGS. 6A and 6B that the higher the rotation speed of the disk and the larger the voltage applied from the outside, the higher the sampling efficiency.

On the other hand, as the rotational speed of the disk increases, a lot of small particles are generated. As the particle size decreases, the electrical mobility of the particles increases, which is better than that of large particles. In addition, since the electrical sampling efficiency is proportional to the intensity of the external electric field, an experimental result in which the intensity of the electric field is proportional to the sampling efficiency is a predicted result. Nevertheless, the reason why the sampling efficiency is higher than that of FIG. 6A when the applied voltage is 0 kV in FIG. 6B is that, as mentioned in the previous performance evaluation, when the sampling flow rate is increased, the flow rate at the sampler nozzle increases, so that the particles This is because the probability of attachment by inertia collision increases. In addition, since the flow rate is large in FIG. 6B and the residence time in the sampler is shorter than that in FIG. 6A, it can be seen that the result of FIG. 6B is lower than that of FIG.

In conclusion, the main collection method in FIG. 6A is by electric force, and the main collection method in FIG. 6B is inertia force. In addition, when the particle sampler is used to collect particulate matter in the actual hard disk drive, the collection efficiency is more than 70% at the disk rotation speed of 5400 rpm or more. The particle sampler uses the particle inertia and electrical mobility characteristics. It can be confirmed that the equipment can be sampled.

The slider type in the hard disk drive used in this experiment was a pico-slider (30% slider), and the size was 1 mm × 1.235 mm × 0.3 mm (shallow depth: 0.2 μm, deep cavity: 2 μm). In addition, the air bearing surface (ABS) of the slider is coated with diamond-like carbon (DLC) on a substrate of Al ₂ O ₃ -TiC material.

7A and 7B show electron microscope images and OJ electron spectroscopic analysis of the slider surface after particle sampling.

First, in FIG. 7A, it can be seen that the slider surface (point 1) is covered with the component of the disc (point 2). This is because the disk is rotated in a state where the slider is not injured (drag) by applying a forced load to the slider during the experiment, and the abrasion phenomenon occurs on the surface by mutual contact when the slider and the disk are rotated. Make it clear.

FIG. 7B is the spectra of the OJ spectroscopy for two points in FIG. 7A. At point 1, the constituents of the disk, P, Ni, etc. were observed, and at point 2, the components C, Al, etc. of the slider were observed. . In the case of O, the component observed at both points, the original constituent may be observed, but since the oxidation reaction occurs in contact with external air during the processing of the slider surface or during the experiment, the surface of the slider surface is more likely to be oxidized. Big. Observations of these O components apply to both the disk surface and the sampling particles, which will be discussed later.

In the case of the disc, aluminum (Al) -magnesium (Mg) is coated with 75, DLC, bump height is 165 ,, and surface diameter (Ra) in the data zone is 8Å It became.

8A is an electron microscopy image of the disk surface in contact with the slider, as with the slider surface, abrasion marks due to mutual contact appear. It is also observed that fine particles are attached in the area of the surface damage due to abrasion, which causes the material coated on the disk surface to be finely crushed, some to adhere to the slider surface, and another to the shape of the particles. This shows that the disk was removed from the disk.

Results for OJ electron spectroscopy analysis for any two points in FIG. 8A are shown in FIG. 8B. Here, at both points, components of P and Ni were observed in the same manner as point 1 of FIG. 7B, and components such as C and Al were additionally observed.

9A and 9B show results obtained by sampling and analyzing particles (flow rate: 1.5 lpm) generated from a hard disk drive using a particle sampler. In FIG. 9A, abrasive particles due to mutual contact between the slider and the disk are observed, the size of which ranges from several μm to less than several hundred nm. Here, nanometer-level particles may have the greatest influence on the collection of externally applied electric force, but larger particles may be captured by collisions due to inertia, not electric force. Therefore, when the particulate matter generated inside the hard disk drive is collected using the particle sampler, it can be confirmed that the particulate matter of various sizes ranging from micrometer size particles to submicrometer size particles can be captured.

 9A shows the results of the OJ electron spectroscopy analysis by selecting two particles. Particles 1 and 2 were found to have the same components, such as P, C, Ni, Al, these components are the same as the components of the disk surface analyzed earlier. Therefore, in this experiment, the particles sampled from the hard disk drive were judged to be abrasion particles due to the interaction between the slider and the disk, and it could be assumed that the particles were mainly separated from the disk surface.

In order to increase the stability and reliability of the hard disk drive, it is essential to remove particles generated internally. This requires accurate analysis of generated particles, and uses a sampling method as one of the first steps for analysis. For this purpose, when the particle sampler is used to sample the particles generated in the hard disk drive, it is easy to sample the fine particles by the applied electric force and the inertial force of the particles, and the flow rate or the applied voltage is adjusted according to the sampling purpose. Particles of size can be collected. The experimental results showed that the sampled particles from the actual hard disk drive were sampled using the designed particle sampler, and the sampling efficiency was higher than 70% .The sampling substrate was separated from the sampler to collect the collected particles using electron microscopy images and OJ electron spectroscopy. The component could be analyzed.

Example 2

Hard disk drives (HDDs), which are now used as the primary information storage medium in almost all PCs, have undergone many technological advances since the 1980s when they were popular. Among them, the improvement of recording density has been very fast, and it is still very important for technology development. In addition, recently, large-capacity and various softwares are generally used, and HDDs with high storage densities are required to realize multimedia such as music and video having huge capacities. Therefore, studies to increase storage densities per unit area of HDDs will continue. It is a prospect.

High performance disk drives also require high disk rotation speeds. Recently, the speed of a typical hard disk drive is increasing from 5400 rpm to 15000 rpm, and a higher speed will be realized later. Therefore, analyzing the particle generation characteristics by the change of driving speed will be very important information for reducing the particulate matter inside the high capacity hard disk drive.

In this embodiment, the experiment was performed on the abrasive particles generated in the head-disk in the hard disk drive. By varying the rotational speed of the disk during the experiment, the generated particles were collected using a particle sampler, and the size of the generated particles was measured by analyzing a sampling substrate on which the particles were collected using an electron microscope.

FIG. 10 is an experimental apparatus for drawing and sampling a particle sampler fabricated to collect particles generated from a hard disk drive. The purpose of collecting the generated particles is to analyze the shape or size distribution through a scanning electron microscope (SEM) photograph. According to the sampler design, most of the submicron particles (<1 μm) among the particles sampled on the collecting plate are collected under the influence of an electric field applied outside the sampler, and also submicron particles close to the micron and particles in the micron region ( > 1 μm) are intended to be collected by inertial impaction. The sampling electrode uses aluminum (Al) material and is supplied with positive or negative power from the power supply to collect the charged particles on the sampling plate by electrical force. The wall of 10) also serves as grounding using the same material of aluminum (Al). The material of the non-conductive plastic was selected so that no electric current flows between the electrode 15 and the ground (wall surface of the particle sampler).

In the experimental diagram, clean air was supplied to the hard disk drive, and the supply flow rate at this time was 1 lpm (nozzle section speed of 8.4 kPa). Here, the flow rate required for sampling is 0.3 lpm and the remaining flow rate is discharged to the outside. At this time, in order to obtain one sample particle specimen, the slider of the hard disk drive was continuously driven for 2000 seconds with the contact and floating cycles, and the applied voltage was negative 500V.

In this experiment, the particles generated by the speed change of the hard disk were sampled through the particle sampler, and the particle shape was observed through the electron microscope.

11A to 11D illustrate photographs taken through an electron microscope by collecting particles generated from a hard disk drive during driving through a particle sampler manufactured in the laboratory.

When comparing the overall particle size of Figures 11a to 11d, it can be seen that the size distribution of the generated particles is the smallest size in Figure 11d. This shows that as the disk rotation speed increases in particle size distribution, the particle size decreases. In order to reduce the contaminant particle inside the hard disk drive, research should focus on nano-sized particles.

The present invention is not limited to the above-described embodiments, but can be variously modified and changed by those skilled in the art, which should be regarded as included in the spirit and scope of the present invention as defined in the appended claims. something to do.

As described above, according to the particle sampler for collecting particulate contaminants generated in the hard disk drive and the performance evaluation device of the particle sampler, micro and sub micro sized particulate matters generated in the hard disk drive are described. At low flow rates, there is no loss and capture and sampled particles can be analyzed by electron microscopy, OJ electron spectroscopy, etc. without additional work.                     

In addition, as a result of performance evaluation, when the sampler is used to collect particulate contaminants generated by the hard disk drive, most of the submicron particles (<1 μm) are collected up to 90% or more under the influence of an electric field applied outside the sampler. In addition, submicron particles close to microns and particles in the micron region (> 1 μm) were captured by inertial impaction up to 90% or more.

Therefore, the particle sampler of the present invention has the effect of collecting particles generated in the hard disk drive regardless of particle size at a lower concentration than the sampler for sampling particles existing in the atmosphere.

In addition, it is effective to separate the sampling substrate from the sampler and analyze the component and size of particulate contaminants collected on the substrate by using an electron microscope image and an OJ electron spectrometer.

Claims (4)

In a particle sampler, A body part having a cylindrical shape through which the upper and lower parts penetrate, and having a discharge hole formed at a side thereof, and forming a positive electrode; An inlet pipe having a nozzle installed at an inner diameter of the upper portion of the body part and introducing particles contained in sampling air inside the hard disk drive to be discharged into the body part through the nozzle; An electrode installed at an inner diameter of the lower portion of the body part, the electrode having a detachable sampling substrate for collecting particles introduced into the body part, the electrode being electrically connected to the sampling substrate to form a negative electrode; A discharge pipe installed at an outlet of the body and discharging particles not collected on the sampling substrate to the outside; A bottom cover installed at an inner diameter of the lower portion of the body part and configured of a non-conductive material to fix the electrode by inserting it in one direction into a hole formed at a center thereof; And And a screw configured to fasten and fix the electrode protruding to the other side of the bottom cover, and to supply power to the electrode. The method of claim 1, The sampling substrate is a particle sampler, characterized in that using any one of a thin aluminum, copper substrate, conductive substrate. delete delete

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