KR101377477B1 - Pleated depth filter - Google Patents

Abstract

The present invention relates to a bent deep filter.
In the bent deep filter of the present invention, at least three or more multilayered nonwoven media having an average pore size gradually increasing from the inner core to the outer circumferential surface are stacked and bent, thereby providing a deep media having an asymmetric pore gradient in cross-sectional structure. In addition, the particle removal efficiency of each pore level is high, and the capacity of collecting slurry particles by size is excellent, and the filtration area is maximized, in particular, to meet physical properties such as improved flow rate compared to a conventional deep filter. Therefore, the bent deep filter of the present invention is useful for slurry filtration of the CMP process,

Description

Bent Type Deep Filter {PLEATED DEPTH FILTER}

The present invention relates to a bent deep filter, and more particularly, a non-woven medium having an average pore size gradually increasing from an inner core to an outer circumferential surface is bent after being laminated in at least three or more layers, thereby resulting in an asymmetric pore gradient in cross-sectional structure. As the provided deep media is provided, the particle removal efficiency for each pore level is high and the capturing ability of the slurry fine particles for each size is excellent, and in particular, it relates to a bent deep filter having improved flow rate by maximizing the filtration area.

Wafer polishing technology using a chemical mechanical planarization (CMP) slurry has advantages such as high polishing efficiency and ease of operation compared to conventional etching methods, and replaces conventional conventional etching processes.

However, a wafer polishing technique using a CMP slurry has a problem in that scratches are generated by large particles in the slurry during polishing. In order to solve this problem, a filter for filtering a CMP slurry in slurry production is used. However, even if the slurry is sufficiently filtered, there is a high possibility that agglomerates are formed at the time of storage, transportation, and dilution depending on pH, temperature, and the like.

Therefore, various types of filters are applied to the actual CMP process. In particular, a number of studies have been reported that slurry filtration using a filter during the CMP process reduces wafer scratches, thereby increasing the yield of the overall process.

The filter used in the CMP process is designed so that larger particles of a certain size or more are selectively collected and removed in the filter structure, and small particles of a certain size or less pass through the filter after filtration for wafer polishing. Therefore, the CMP filter has the characteristics of particle separation rather than particle removal, and therefore, an absolute grade level of particle exclusion performance is required.

Generally, the process filter for filtration is classified into a deep filter in the form of a cartridge and a membrane filter in the form of a membrane.

Membrane filters are typically manufactured in the form of cartridges by bending thin membranes of several tens of microns and have a high level of flow characteristics due to the maximum surface area. In the membrane filter, particles are removed by pores formed on the surface of the thin polymer membrane, and all particles larger than the pore size are removed. However, CMP slurries have a very high solids content compared to the process solution, and when a filter in the form of a membrane is applied, pore closure by solid particles occurs immediately after filtration, which is not suitable.

Thus, for filtration of CMP slurry, a filter having a deep structure is generally preferred.

The depth filter is not a surface filtration but a slurry filtration mechanism that removes particles by trapping particles in the filter while passing through a nonlinear tortuosity in a media layer having a thickness of several mm to several tens of mm.

However, due to the characteristics of the removal mechanism, the depth of particle removal is not sharper than that of the membrane filter when the depth filter is used, and there is another problem that a small amount of large particles may exist even after filtration.

Therefore, in order to solve this problem, the core technology of maximizing the removal performance and extending the service life as much as possible by optimizing the type and structural design of the fiber media constituting the filter when manufacturing the depth filter for slurry filtration in the CMP process To be.

The depth filter used for particle removal is generally a method of manufacturing a filter in a cylindrical shape on the surface of the core by winding the nonwoven fabric in the core or direct polymer spinning.

In order to maximize the filtration area of such a depth filter, a bend-type depth filter is manufactured by directly bending and bending a radial or sheet-like filter material in a cylindrical shape to have a thickness of 1 to 5 mm. The depth filter of this type has a thinner media thickness than that of a conventional depth filter formed by repeatedly winding a filter, that is, the slurry migration path in the filter is shorter, thereby reducing particle removal and trapping ability, but providing a large filtration area. Excellent characteristics

In addition, unlike a thin film filter, the media has a certain thickness, thereby having a morphological characteristic that has all the advantages of the bent deep filter. In particular, it is mainly used for large-scale continuous filtration to remove large particles in the slurry and agglomerates that may occur during storage and dilution in the slurry storage unit or the central supply unit requiring high flow rate characteristics.

As a method of manufacturing the bent deep filter, a method of bending after cylindrical direct spinning and a method of bending after laminating sheet-like media are used.

At this time, the bent deep filter manufactured by direct spinning on the core surface by bending and bending is difficult to verify the performance of the melt blown by layer in the product design by grade, so that only the finished product stage performance evaluation of a certain thickness is possible. The deviation tends to be large.

In addition, the sheet lamination method has a merit that it is possible to verify and evaluate the performance of the media at the sheet level, thereby reducing the variation of the product.

When the media of the filter structure is a deep structure of the conventionally manufactured bend type deep filter, the particle removal ability is excellent, but the flow rate is reduced due to the limited filtration area, and the bent structure has a high filtration area, but the flow rate is excellent. In order to be applied in the same housing size, the thickness of the media must be thinner, so the particle trapping ability is lowered.

Accordingly, the present inventors have attempted to solve the problems of the prior art, by laminating and bending the multi-layered nonwoven media consisting of at least three or more so that the average pore size gradually increases from the inner core to the outer circumferential surface, thereby laminating by pore level As a result, the present invention has been completed by providing a bend-type depth filter having a high particle excretion level, an excellent fine particle trapping ability, and especially a filtration area that is maximized, compared to a conventional depth filter, and with improved flow rate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a bent deep filter having an improved internal structure in which a multi-layered nonwoven media provided with an asymmetric pore gradient is laminated and bent.

Another object of the present invention is to provide a deeper media that is bent after lamination of a multi-layered non-woven media consisting of at least three of which the average pore size gradually increases from the inner core to the outer circumferential surface. It is an excellent, particularly maximized filtration area to provide a bent deep filter with improved flow rate.

In order to achieve the above object, the present invention is to arrange the first support body, the multi-layer non-woven media and the second support body consisting of at least three or more so that the average pore size gradually increases from the inner core to the outer peripheral surface It provides a bent deep filter that is folded after lamination and has a deep media having an asymmetric pore gradient in its cross-sectional structure housed in an outer case.

In the bent deep filter of the present invention, the multi-layered nonwoven media has a thickness of 1.0 to 5.0 mm.

Moreover, the diameter of the fiber which comprises the said multilayer nonwoven fabric media is 0.1-20 micrometers, and the average pore diameter is 1.0-20 micrometers.

The multilayer nonwoven media is a single or mixed material selected from the group consisting of polyethylene, polypropylene, polyester, polyolefin and polyamide.

In addition, the multi-layered nonwoven media is preferably made of a nonwoven media by the meltblown method, more preferably in the form of a combination of the nonwoven media by the meltblown method and the nonwoven media by the spunbond or calendering method By doing so, it is possible to manufacture a depth filter that can control a variety of average pore size, removal efficiency, flow rate level.

The bend-type deep filter of the present invention is manufactured by bending the multilayer nonwoven filter media within an acid height of 0.7 to 1.5 mm and an acid number of 15 to 50.

The bend-type deep filter of the present invention has a multi-layered nonwoven filter media having a deep media that is bent after lamination of a multi-layered nonwoven fabric composed of at least three or more layers such that the average pore size gradually increases from the inner core to the outer circumferential surface. The particle removal efficiency by pore level is high and the slurry particle collecting ability by size is excellent, and in particular, the flow rate is improved compared to the conventional depth filter.

Accordingly, the present invention is to provide a bent deep filter optimized for slurry filtration of the CMP process.

Hereinafter, the present invention will be described in more detail.

The present invention, the first support from the inner core side,

Multi-layered non-woven media consisting of at least three or more so that the average pore diameter gradually increases from the inner core to the outer circumferential surface; and

It provides a bend-type depth filter in which the second support is laminated and then bent to be arranged to have a deep media having an asymmetric pore gradient in the cross-sectional structure.

Accordingly, the bent deep filter of the present invention includes a deep media that are bent after stacking at least three or more layers of non-woven media provided with an asymmetric pore gradient whose average pore size gradually increases from the inner core to the outer circumferential surface. It is characterized by

Hereinafter, the configuration of the deep media of the present invention will be described in detail.

The multi-layered nonwoven media constituting the deep media of the present invention is designed to increase the particle removal efficiency by pore level and increase the fine particle trapping ability by increasing the slurry migration path in the filter by securing a constant thickness of 1.0 to 5.0 mm. do. Thus, more preferably, the thickness of the multi-layered nonwoven media is secured to 2.0 to 4.0 mm. If the thickness of the multi-layered nonwoven media is less than 1.0 mm, the slurry migration path is too short to expect the desired filter performance. If the thickness exceeds 5.0 mm, the particle capture performance is improved, but the depth media is thick, so that the housing fixing operation is performed. There is difficulty.

In addition, in the present invention, the multi-layered nonwoven fabric has a fiber diameter of 0.1 to 20 µm and an average pore diameter of 1.0 to 20 µm, and gradually increases from an inner core to an outer circumferential surface. An asymmetric pore gradient is given to increase. In this case, the multi-layered media may be composed of at least three or more layers, preferably three to five layers, and various individual media may be combined in a fiber diameter and an average pore condition to be changed in design as long as it meets the asymmetric pore gradient. will be.

Thus, in the present invention, since the multi-layered nonwoven media is formed with a structure having an asymmetric pore gradient, the differential pressure increases as the flow path (tortuosity) in the deep media increases, but the particle removal efficiency for each pore level is high and the slurry for each size is increased from high porosity. The collecting ability of the particles is excellent, especially the use cycle is increased.

Therefore, the multi-layered nonwoven media having at least three or more layers are laminated and bent, and the bend-type depth filter having depth media provided with an asymmetric pore gradient in cross-sectional structure is controlled by controlling the diameter of the average fibers constituting the multilayer nonwoven media. It is possible to control the collection capacity change by particle size, and to control the removal efficiency and use cycle of the filter accordingly.

The multi-layered nonwoven media comprising at least three of the present invention is preferably a single or mixed material selected from the group consisting of polyethylene, polypropylene, polyester, polyolefin and polyamide, and in the embodiment of the present invention, polypropylene Although described using, it will not be limited thereto.

The multilayer nonwoven media consists of a nonwoven media produced by any one method selected from spunbond, thermal bonding, spunlace, meltblown, flashspun and needlepunching.

Specifically, the multi-layered nonwoven media may be 1.0 to 5.0 mm thick as the nonwoven media by the meltblown method, and more preferably, the nonwoven media by the meltblown method and the other by the spunbond or calendering method. The nonwoven media is made of a combined form.

In this case, the combination form of the nonwoven media is more advantageous to realize an average pore size of 1 μm or less than when the depth media thickness (1.0 to 5.0 mm thickness) is composed of the meltblown nonwoven media alone, and is 0.1 to 1.0 μm. Easy removal of fine particles

Thus, the melt blown nonwoven fabric material can be configured by laminating one to three nonwoven fabric materials by the calendering method by compressing at a predetermined pressure and temperature to reduce the average pore size by the average pore size. In this case, the nonwoven fabric filter by calendering means that these nonwoven fabric filters are compressed under a certain pressure and temperature, and the average pore size is reduced to 10% to 90% of the nonwoven fabric before calendering. The average pore size of the combined form satisfies 0.1 to 1.0 μm.

The nonwoven fabric material by the calendering method has a thickness of 0.1 to 0.3 μm and an average pore size of 0.1 to 1.0 μm, and the thickness is relatively thinner than that of the meltblown nonwoven fabric material. In order to realize the same thickness, one to three sheets are laminated, The average pore size can satisfy 1.0 mu m or less.

For example, in the case of inserting two or more nonwoven media by calendering method by the average pore size together with the meltblown nonwoven media, a meltblown nonwoven media is formed between the nonwoven media by calendering method and the surface roughness is relatively The flow path can be secured between the nonwoven fabric media by the small calendering method, which is more preferable.

In the bent deep filter of the present invention, unlike the bent deep filter manufactured by directly spinning the nonwoven fabric to the filter core, the bent deep filter is laminated by bending at least three or more nonwoven media having different average pore sizes in a multi-layered manner, so that the particle removal efficiency for each pore level is increased. Not only is the high and excellent size of slurry particle size collecting ability, it is also easy to evaluate the performance of the individual media layer, thereby minimizing the performance deviation of the product.

In other words, according to the depth structure, the cylindrical bent deep filter of the present invention by imparting an asymmetric pore gradient such that the average pore size of the nonwoven fabric constituting the individual filter layer gradually increases from the inner core to the outer peripheral surface, thereby, the filter outer layer Relatively large particles are collected and removed at the filter and small particles are collected in the filter inner layer.

The cylindrical bent deep filter of the present invention is designed to gradually increase the size of the average pore size according to the diameter of the filter, the non-woven medium having a different fiber diameter and average pore size when the non-woven medium filter composition, the relatively large particles in the filter outer layer By collecting small particles in the filter inner layer, it is configured to improve the particle removal efficiency and product life.

In summary, the bent deep filter of the present invention has a high depth of particle removal efficiency by pore level and excellent ability to collect slurry particles by size due to a deep structure, and in particular, due to the bent structure, the filtration area is maximized, resulting in a flow rate compared to a conventional deep filter. Preferably, it meets a flow rate of 9.0 to 25 LPM / psi and at the same time meet the 90% or more fine dust and slurry fine particle removal efficiency, it is optimized for slurry filtration of the CMP process.

In the bent deep filter of the present invention, the bicomponent core is manufactured by winding a nonwoven fabric of sheet form prepared by melt spinning polypropylene and polyethylene materials while providing heat, and having a thickness of about 4 to 6 mm. do. At this time, the average pore size of the nonwoven fabric constituting the bicomponent core is preferably several tens of micrometers or more.

In the bent deep filter of the present invention, the support is made of the same material as the core, and the thickness of the support is preferably 0.5 to 0.8 mm.

The support is preferably configured in the form of a mesh. The mesh form serves as a support for maintaining a stable shape, and helps to secure a flow path that allows the filter surface area provided by the bending to be used for filtration. At this time, the support should not have a flow resistance when the fluid passing through the nonwoven media is filtered.

Since the nonwoven media is laminated in multiple layers by fiber diameter, average pore size, and thickness between the first support and the second support in the form of a mesh, and then bent together, the acid height is 0.7 to 1.5 mm compared to the conventional deep filter specification. The range is preferable, and the number of acids is preferably 15 to 50.

The bending structure may vary depending on the thickness. In this case, the arithmetic number may be changed to be fixed to the housing of the cartridge standard, and may be changed according to the thickness of the depth media. Specifically, if the depth of the media is thick, the number of arithmetic will be less, and if the depth of the media is thinner, more acid may be constructed. However, if a thicker depth media is applied and the number of acidic water is increased, the filling density in the housing is increased, the filtration will be difficult to occur over the entire filtration area and the flow rate will be reduced. Thus, in the bending structure of the bent deep filter of the present invention, the number of mountains, the height of the mountain and the shape of the mountain are important factors that affect the physical properties of the filter.

Hereinafter, the present invention will be described in more detail with reference to Examples.

This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

≪ Example 1 >

It is made of polypropylene nonwoven fabric produced by the melt blown method, but the first filter medium has an average pore diameter of 3㎛, the average fiber diameter 1.1㎛, thickness 0.26mm, the second medium has an average pore diameter of 10㎛, average fiber diameter 1.9㎛, thickness 0.65mm, the third filter media prepared a multi-layered nonwoven media consisting of an average pore diameter of 20㎛, an average fiber diameter of 3.2㎛, 0.54mm thickness.

One sheet each was laminated in the order of the mesh support, the first filter, the second filter, the third filter, and the mesh support from the core side. The nonwoven fabric was bent at intervals of about 1 cm, and the depth of the bending media in the filter was 20 so that the filter length was 10 inches, and then fixed with an external casing to produce a deep filter in the form of a cartridge.

<Example 2>

The non-woven fabric prepared in Example 1 is used, except that the lamination is performed in the order of the mesh support, two first medians, two second medians, two third medians, and a mesh support from the core side. In the same manner as in 1, a deep filter in the form of a cartridge was manufactured.

<Example 3>

Multilayered nonwoven media consisted of three layers, the first media consisted of one sheet of polypropylene nonwoven media by the calendering method with an average pore diameter of 0.7 μm, an average fiber diameter of 2.4 um, and a thickness of 0.2 mm. Eight sheets of polypropylene nonwoven fabrics produced by the melt blown method having a thickness of 3 μm, an average fiber diameter of 1.1 μm, and a thickness of 0.26 mm were laminated. The third filter medium was an average pore diameter of 10 μm, an average fiber diameter of 1.9 μm, and a thickness of 0.65 mm. It consisted of a polypropylene nonwoven media produced by the tumble method. From the core side, and stacked in the order of the mesh support, the first filter, the second filter, the third filter and the mesh support, the depth of the depth filter media is carried out at the same level as Example 2, except that A bent deep filter was fabricated in the same manner.

&Lt; Comparative Example 1 &

Using the three-layered multi-layered nonwoven media prepared in Example 1, but maintaining the same insertion amount as in Example 1 and rolling in sequence from the core side to the first, second and third media in order The filter of was produced.

Comparative Example 2

It consisted of a deep media consisting of polypropylene nonwoven media produced by the melt blown method of average pore diameter 3㎛, average fiber diameter 1.1um, thickness 0.26mm, but the media were composed of the same thickness of Example 2, After application of the bidirectional mesh support, the same method was used to fabricate a deep filter in the form of a cartridge.

<Experimental Example 1>

For the cylindrical deep filters manufactured in Examples 1 to 3 and Comparative Examples 1 to 2, the flow rate and the removal efficiency were measured by the following method, and the results are shown in Table 1 below.

1. Flow Measurement

The pure water of 18MΩ was filtered, and the treated flow rate according to the initial pressure was measured by a flow meter and expressed as LPM / psi.

2. Determination of Particle Removal Capacity (1)

ISO Fine Test Dust was mixed with pure water at a constant rate and administered through a gear pump, and the number of particles having a size of 1 μm or more before and after the filter was measured and the change in the number of particles was expressed as a percentage.

3. Determination of Particle Removal Capacity (2)

The CMP slurry was diluted in pure water and administered through a gear pump, and the number of particles having a size of 1 μm or more before and after the filter was measured and the change in the number of particles was expressed as a percentage.

As confirmed in Table 1, Example 1 and Example 2 formed the deep media with three layers of non-woven media made of the same material, but Example 2 doubled the thickness by inserting two sheets of media. Structure. As a result, the filter differential pressure was increased because the friction against the flow was increased when the insertion amount of the media was increased, but both the fine dust standard particles and the slurry fine particles removal efficiency were increased.

Comparative Example 1 is produced by inserting the same type of media and the same amount of media as Example 1, while Example 1 is a deep-layer bending filter of the sheet lamination method, while Comparative Example 1 was manufactured by repeatedly winding sequentially It is composed of general depth filter. As a result, in Example 1, compared to Comparative Example 1, the filtration area was increased due to the bending structure of the nonwoven media, resulting in a flow rate improvement of 2 times or more. However, the removal efficiency of the slurry fine particles was somewhat increased due to the expansion of the filtration area. It is confirmed that it is greatly advantageous in terms of flow rate.

Example 3 is a structure in which one sheet of polypropylene nonwoven fabric media by a calendering method having an average pore diameter of 0.7 μm was inserted into a core innermost angle, and a gradient was applied to average pores. Comparative Example 2 is a second media layer of Example 3 Deep media of the same thickness were composed only of the nonwoven media produced by the meltblown having a mean pore diameter of 3 μm. As a result, in Example 3, the flow rate was reduced compared to Comparative Example 2, but the particle removal efficiency of 1 μm or more was greatly improved.

Therefore, the bent deep filter of the present invention meets the flow rate of 9.0 to 25 LPM / psi, the fine dust and slurry fine particle removal efficiency was more than 90%.

As described above, the present invention was manufactured by stacking and bending together a multi-layered non-woven media provided with an asymmetric pore gradient, thereby providing a bent deep filter having improved internal structure.

Accordingly, the bend-type deep filter of the present invention has a deep structure that allows the average pore size to gradually increase from the inner core to the outer circumferential surface, thereby increasing particle removal efficiency by pore level and improving slurry fine particle collecting ability by size. In particular, due to the bent structure, it is possible to maximize the filtration area to improve the flow rate, compared to the conventional deep filter.

Furthermore, the bent deep filter of the present invention can be usefully used for slurry filtration of the CMP process.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. .

Claims (8)

From the inner core side, the first support, the multi-layered non-woven fabric made up of at least three and the second support are laminated so as to be arranged, bent and stored in the outer case,
The multi-layered nonwoven media is folded between at least three different fiber diameters, average pore diameters, and thicknesses between the first and second support bodies, and is bent, and the average pore size gradually increases from the inner core to the outer circumferential surface. Bending depth filter, characterized in that the asymmetric pore gradient is given on the bent cross-sectional structure. The bent depth filter of claim 1, wherein the multilayer nonwoven filter media comprises at least three or more different thicknesses in a thickness range of 1.0 to 5.0 mm. The bent deep filter according to claim 1, wherein the multi-layered nonwoven filter member comprises at least three or more fiber diameters different from each other in a fiber diameter of 0.1 to 20 µm. The bent depth filter according to claim 1, wherein the multilayer nonwoven media is provided with an asymmetric pore gradient gradually increasing from an inner core to an outer circumferential surface in an average pore size of 1.0 to 20 µm. The bent depth filter according to claim 1, wherein the multi-layered nonwoven media is single or mixed material selected from the group consisting of polyethylene, polypropylene, polyester and polyamide. The bent depth filter according to claim 1, wherein the multi-layered nonwoven media is made of a nonwoven media by a melt blown method. The bent depth filter according to claim 1, wherein the multi-layered nonwoven filter media is formed by combining a nonwoven fabric filter by a melt blown method and a nonwoven fabric filter by a spun bond or calendering method. The bent depth filter according to claim 1, wherein the multilayer nonwoven media is bent to an acid height of 0.7 to 1.5 mm and an acid number of 15 to 50.