JP2013078932A - Screen printing matrix, method of manufacturing stacked ceramic capacitor using the same, and the stacked ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screen printing matrix, a method of manufacturing a stacked ceramic capacitor using the matrix, and the stacked ceramic capacitor.SOLUTION: The screen printing matrix is provided, which includes: a screen mesh having a plurality of through-holes; a mask formed by filling part of the plurality of the through-holes; at least one print area defined by the mask; and a pair of walls oppositely disposed at a predetermined interval from both peripheral parts of the print area.

Description

The present invention relates to a screen printing plate, a method for manufacturing a multilayer ceramic capacitor using the same, and a multilayer ceramic capacitor.

Multi-Layered Ceramic Capacitors (MLCCs) are mounted on printed circuit boards of many electronic products such as mobile communication terminals, notebook computers, computers and personal digital assistants (PDAs), and are filled with electricity. Alternatively, it is a chip-shaped capacitor that plays an important role of discharging, and has various sizes and laminated forms depending on the intended use and capacity.

Recently, with the miniaturization of electronic products, there has been a demand for ultra-miniaturization and ultra-high capacity of such multilayer ceramic capacitors. For ultra-miniaturization, the internal electrodes and dielectric layers have been made thinner and ultra-high. A product in which many dielectrics are laminated for the purpose of increasing the capacity is manufactured.

However, in the multilayer ceramic capacitor composed of many layers of dielectrics, the discharge amount of the peripheral part is larger than that of the central part at the stage of filling the conductive paste through the screen printing plate to form the internal electrode film on the sheet. There are relatively many cases.

Therefore, a so-called saddle phenomenon in which the peripheral portion of the internal electrode film bulges upward and the thickness thereof becomes thicker than the central portion may occur.

Such a saddle phenomenon may cause the peripheral part of the relatively thick internal electrode film to extend more than the central part in order to make the density uniform when a laminated body made of a multilayer dielectric is pressure-bonded. As a result, the sheet becomes thinner as a whole, and the reliability of the manufactured product is reduced.

In this technical field, when manufacturing a dielectric of a multilayer ceramic capacitor, a new method for improving the saddle phenomenon generated in the internal electrode film has been demanded.

One aspect of the present invention is a screen mesh having a plurality of through holes, a mask portion formed by filling a part of the plurality of through holes, and at least one printing region defined by the mask portion, There is provided a screen printing plate including a pair of wall portions opposed to each other at a predetermined interval from both peripheral portions of the printing area.

In an embodiment of the present invention, a distance between the wall portion and the peripheral portion of the print region may be 30 to 100 μm.

In the embodiment of the present invention, the pair of wall portions may be arranged side by side.

In one embodiment of the present invention, the wall may have a width of 5 to 20 μm.

In one embodiment of the present invention, the print area may be formed in two or more rows on the screen mesh.

At this time, the printing areas of the respective rows can be arranged side by side, and the first printing area of the first row and the second printing area of the second row adjacent to the first printing area are shifted from each other. be able to.

In one embodiment of the present invention, the wall portion may be formed to be lower than the height of the printing region, and the end portion of the wall portion facing the sheet and one surface of the mask portion may be formed to have a step.

The wall portion according to an embodiment of the present invention may be formed with a bulging end toward the sheet.

The wall portion according to an embodiment of the present invention may be formed with a recessed end toward the sheet.

In one embodiment of the present invention, the wall portion may be formed so that the lengths on the left and right sides of the end toward the sheet are different.

In one embodiment of the present invention, the wall portion may have a concavo-convex portion at an end toward the sheet.

According to another aspect of the present invention, a screen printing plate having at least one printing area is disposed on a sheet, an electrically conductive paste is supplied to the printing area to form an internal electrode film on the sheet, and the printing area A method of manufacturing a multilayer ceramic capacitor is provided, wherein a part of the conductive paste is cut off by a pair of wall portions arranged at predetermined intervals from both peripheral portions.

In an embodiment of the present invention, the sheet is formed at a position corresponding to the wall portion of the sheet by a conductive paste that has passed through the open through-hole around the wall portion in a portion without the wall portion. The internal electrode film can be formed so as to have a surface with the same height.

The screen printing plate according to an embodiment of the present invention may be provided at a predetermined distance from the upper surface of the sheet.

According to one embodiment of the present invention, when an internal electrode film is formed on a sheet, a saddle phenomenon generated on the upper surface of the internal electrode film is suppressed to manufacture a multilayer ceramic capacitor having improved operation reliability. Expected to be effective.

1 is a perspective view showing a schematic structure of a screen printing plate according to an embodiment of the present invention. It is a top view of FIG. It is sectional drawing which shows the internal electrode film | membrane formed using the sheet | seat applied to one Embodiment of this invention, and the screen printing board by one Embodiment of this invention in the AA line cross section of FIG. It is sectional drawing which shows the Example which changed the form of the wall part of the screen printing board by one Embodiment of this invention. It is sectional drawing which shows the Example which changed the form of the wall part of the screen printing board by one Embodiment of this invention. It is sectional drawing which shows the Example which changed the form of the wall part of the screen printing board by one Embodiment of this invention. It is sectional drawing which shows the Example which changed the form of the wall part of the screen printing board by one Embodiment of this invention. It is sectional drawing which shows the Example which changed the form of the wall part of the screen printing board by one Embodiment of this invention. It is sectional drawing which shows the sheet | seat applied to one Embodiment of this invention, the screen printing board by other embodiment of this invention, and the internal electrode film formed using this screen printing board.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

However, the embodiments of the present invention can be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

In addition, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

Accordingly, the shape and size of elements in the drawings may be exaggerated for a clearer description, and elements denoted by the same reference numerals in the drawings are the same elements.

In addition, the same reference numerals are used throughout the drawings for parts having similar functions and operations.

Further, throughout the specification, “including” a component means that the component can include other components rather than excluding other components unless specifically stated to the contrary. To do.

Referring to FIGS. 1 and 2, the screen printing plate 10 according to the present embodiment fills a screen mesh 13 having a plurality of through holes 14 and a part of the plurality of through holes 14 of the screen mesh 13 into a non-penetrating state. And a pair of wall portions 20 arranged to face each other at a predetermined interval from both peripheral portions in the printing region 12. Including.

The screen mesh 13 can be made of a material such as polyester or stainless steel, and can be formed in a net plate shape having a large number of micro-opened through holes 14.

The mask part 11 can be a film having a constant thickness made of an emulsion such as an emulsion, and only the part printed on the upper surface of the sheet 30 of the conductive paste supplied to the upper surface of the screen mesh 13 is passed through. The remaining part plays a role of blocking. At this time, the sheet 30 may be a ceramic green sheet.

When the screen printing plate 10 is arranged on the sheet 30 and the conductive paste is supplied onto the printing area 12, the supplied conductive paste is passed downward to print a pattern on the sheet 30. This is for forming the internal electrode film 40.

At this time, the printing region 12 provided in the screen mesh 13 can be formed by arranging two or more rows. In addition, when cutting into chips, the first print area in the first row and the second print area in the second row adjacent to the first print area can be arranged so as to have different polarities.

The wall portion 20 can be formed in the printing region 12 in the vertical direction by filling a part of the through hole 14 of the screen mesh 13 with an emulsion such as an emulsion.

Such a wall portion 20 serves to prevent the filling amount of the conductive paste from becoming relatively larger in the peripheral portion of the printing region 12 than in the central portion. At this time, the distance between the wall portion 20 and the inner surface of the printing region 12 can be set to 30 to 100 μm, which is a distance that can optimize the discharge amount of the conductive paste.

Therefore, the supply of the conductive paste discharged to the printing region 12 is blocked by the wall portion 20 at the peripheral portion thereof, and the filling amount of the central portion and the peripheral portion of the printing region 12 becomes substantially equal. At this time, when the internal electrode film 40 is formed by the conductive paste filled in the peripheral portion of the end portion of the wall portion 20 facing the sheet 30, the barrier wall pushes and suppresses the protrusion of the upper surface of the internal electrode film. Also plays a role.

By such an action, the saddle phenomenon in which the peripheral portion of the internal electrode film 40 swells and protrudes from the central portion is prevented, and thereby the thickness of the internal electrode film 40 can be made uniform to the maximum.

Therefore, when a ceramic laminate is formed by laminating a plurality of sheets 30 provided with the internal electrode film 40, the shape of the internal electrode film 40 is deformed because the upper surface of the internal electrode film 40 is substantially flat. The occurrence of cracks in the internal electrode film 40 during firing can be prevented, and the reliability of the product can be improved.

On the other hand, if the width of the wall portion 20 is too narrow or too wide, the above-described saddle phenomenon may be prevented and the effect of improving the characteristics of the dielectric may not appear.

After producing a plurality of screen printing plates with different widths of the wall portion 20, the ceramic green sheets 30 on which the internal electrode films 40 were formed were produced using the screen printing plates 10. Thereafter, the shape of the printed pattern of the internal electrode film 40 was evaluated, a plurality of the sheets were laminated to produce a green ceramic laminate, and the results of comparing the characteristics are shown in Table 1.

The green ceramic laminate is formed by laminating 150 to 1,000 layers of ceramic green sheets 30 and then sequentially pressing, cutting, firing, external electrodes, plating, and the like to produce a multilayer ceramic capacitor. Evaluation was made with respect to capacitance, breakdown voltage (BDV), shipping accelerated life, and the like.

<Results of characteristics evaluation of green ceramic laminate by wall width>
Referring to Table 1 above, as a conventional example, when a screen printing plate without a wall portion is used in the printing area, the discharge amount of the conductive paste in the peripheral area of the printing area is relative to the central area of the printing area. To be more. As a result, the peripheral part of the internal electrode film formed on the green sheet has a saddle shape protruding relatively from the central part.

After producing a green ceramic laminate by laminating a plurality of sheets having such saddle-shaped internal electrode films, the characteristics were examined.

As a result, the capacitance indicating the size of the space where electricity can be stored is the highest at 107%, the breakdown voltage for dielectric breakdown is 75V, the accelerated shipping life is 31%, and the capacitance is Except for this, it can be seen that the performance is generally low.

As an example to be compared with this, the example in which the width of the wall portion 20 of the screen printing plate 10 is in the range of 5 to 20 μm is given. In the case of such an embodiment, the discharge amount of the conductive paste is adjusted by the wall portion 20 at the peripheral portion of the printing region 12. Therefore, it is possible to prevent a saddle phenomenon in which the peripheral portion of the internal electrode film 40 formed on the sheet 30 protrudes relatively from the central portion.

Therefore, the internal electrode film 40 formed on the sheet 30 has a shape in which the upper surface is substantially flat and the difference in thickness between the peripheral portion and the central portion is less than 10%. In addition, the occurrence of cracks and delamination due to the difference in thickness between the peripheral portion and the central portion of the internal electrode film 40 can be prevented.

After producing a green ceramic laminate by laminating a plurality of sheets 30 having such an internal electrode film 40, the characteristics thereof were examined.

As a result, the capacitance is 106% when the width of the wall 20 of Example 1 is 5 μm, and 104% when the width of the wall 20 of Example 2 is 10 μm. When the width of the wall portion 20 is 20 μm, it is 101%, and in Examples 1 to 3 where the width of the wall portion 20 is 5 to 20 μm, all the capacitances are excellent at 100% or more.

Moreover, in the breakdown voltage, when the width of the wall portion 20 of Example 1 is 5 μm, it is 85 V, and when the width of the wall portion 20 of Example 2 is 10 μm, it is 93 V. In Examples 1 to 3 in which the width is 20 μm and the width of the wall portion 20 is 5 to 20 μm, all of the breakdown voltages are 85 V or more, so the breakdown voltage is higher than that of the conventional 75 V with no wall portion. It can be seen that the voltage has been improved.

Further, in the shipping accelerated life, the wall of Example 3 is 15% when the width of the wall 20 of Example 1 is 5 μm, and 10% when the width of the wall 20 of Example 2 is 10 μm. Examples 1 to 3 in which the width of the portion 20 is 20 μm and 12%, and the width of the wall portion 20 is 5 to 20 μm are all 15% or less in the accelerated shipping life, so there is no wall portion. It can be seen that the accelerated shipping life was improved from 31% of the conventional example.

From the above results, in the case of the present embodiment, it is possible to efficiently suppress a decrease in insulation resistance and the like and to manufacture a highly reliable multilayer ceramic capacitor as compared with the conventional example.

On the other hand, as a comparative example to be compared with the above-described example, a case where the width of the wall portion of the screen printing plate is in the range of 30 to 50 μm is given as an example. In the case of such a comparative example, the discharge amount of the conductive paste is relatively smaller at the periphery of the print area than at the center of the print area. Therefore, the peripheral part of the internal electrode film formed on the green sheet has a shape that is relatively recessed from the central part.

After manufacturing a green ceramic laminate by laminating a plurality of sheets having recesses on the upper surface, the characteristics were examined.

As a result, in terms of capacitance, the comparative example 1 had a wall width of 95% when the wall portion was 30 μm, and the comparative example 2 had a wall width of 40% and was 92%. When the width of the wall portion is 50 μm, it is 88%, and in Comparative Examples 1 to 3 where the width of the wall portion is 30 to 50 μm, all the capacitances are as low as less than 100%. It can be seen that such a capacitance gradually decreases as the width of the wall portion increases.

Moreover, in the breakdown voltage, when the width of the wall portion of Comparative Example 1 is 30 μm, it is 81 V, and when the width of the wall portion of Comparative Example 2 is 40 μm, it is 74 V. When the width is 50 μm, the voltage is 72V, and the widths of the walls are 30 to 50 μm. In Comparative Examples 1 to 3, the breakdown voltage is less than 85V, which is lower than that of the example. It turns out that it falls gradually, so that the width | variety of a part becomes large.

In addition, in the shipping accelerated life, when the width of the wall portion of Comparative Example 1 is 30 μm, it is 18%, and when the width of the wall portion of Comparative Example 2 is 40 μm, it is 27%. When the width of the wall is 50 μm, it is 35%, and in Comparative Examples 1 to 3 where the width of the wall is 30 to 50 μm, the shipping accelerated life reaches 15%, which is the lowest value of Example 1. It can be seen that at 18% or more, such a shipping accelerated life significantly decreases as the width of the wall increases.

Therefore, it can be seen that Examples 1 to 3 according to an embodiment of the present invention have better operation reliability than the conventional examples and Comparative Examples 1 to 3. Considering all of the capacitance, breakdown voltage, and shipping accelerated life, the preferable width of the wall portion 20 is 30 μm or less, more preferably 5 to 20 μm. As a result, the multilayer ceramic capacitor manufactured using the green ceramic multilayer body of Examples 1 to 3 is expected to have optimized performance.

On the other hand, in the present embodiment, the end portion of the wall portion 20 facing the sheet 30 is described as having a flat surface. However, the wall portion of the present invention is a wall as shown in FIG. 4A. The surface of the portion 21 facing the sheet 30 is formed by a convex surface 21a, and the surface of the wall portion 22 facing the sheet 30 is formed by a concave surface 22 as shown in FIG. 4B, as shown in FIGS. 4C and 4D. As shown, the surfaces of the wall portions 23 and 24 facing the sheet 30 can be formed in such a manner that at least one side thereof is inclined with different lengths on the left and right sides. Moreover, as shown in FIG. 4E, the surface of the wall portion 25 facing the sheet 30 can be configured with an uneven surface 25a as necessary.

Referring to FIG. 5, the wall portion 26 according to the embodiment of the present invention may be formed to be lower than the height of the printing region 12. That is, the end portion of the wall portion 26 and one surface of the mask portion 11 can be formed to have a step so that a predetermined gap h is formed between the end portion toward the sheet 30.

In this case, since the gap h can secondarily adjust the filling amount of the conductive paste, the width of the wall portion 26 can be adjusted by the height of the gap h. Therefore, when the wall portion 26 having such a structure is applied to the screen printing plate 10 having a narrow printing area 12, the design becomes easier, for example, the width of the wall portion 26 is further reduced.

Hereinafter, an embodiment of a method for manufacturing a multilayer ceramic capacitor using a screen printing plate according to an embodiment of the present invention configured as described above will be described.

A ceramic powder, a polymer and a solvent are mixed to produce a slurry, which is then applied by a method such as a doctor blade.

The ceramic powder may include a BaTiO ₃ based material. However, not limited thereto, calcium BaTiO ₃ (Ca), and zirconium (Zr) is partially shared _{(Ba 1-x Ca x)} TiO 3, Ba (Ti 1-y Ca y) O 3, _{(Ba 1-x Ca x)} (Ti 1-y) Zr y) O 3 or _{Ba (Ti 1-y Zr y} ) O 3 , and the like. At this time, the average particle size of the ceramic powder is preferably 1.0 μm or less.

Also, a ceramic additive, an organic solvent, a plasticizer, a binder, and a dispersing agent may be blended with such a ceramic powder material, and a slurry may be manufactured using a basket mill.

Thereafter, the prepared slurry is coated on a carrier film and dried to produce a ceramic green sheet 30 with a thickness of about several μm.

The ceramic green sheet 30 may further include a transition metal, a rare earth element, magnesium (Mg), aluminum (Al), or the like together with ceramic powder as a basic material.

Further, in order to lower the sintering temperature, a glass component sintering preparation may be further included. The sintered preparation of the glass component is not limited to a specific component, and may be, for example, a silicon dioxide-based glass component containing an element such as B, Ba, Ca, Al, or Li.

Then, a conductive paste is printed on the ceramic green sheet 30 with a thickness of about 1 to 2 μm to form the internal electrode film 40. At this time, a screen printing method or a gravure printing method can be used as a method for printing the conductive paste. In addition, the conductive paste is formed of one of a noble metal material such as silver (Ag), lead (Pb), and platinum, and nickel (Ni) and copper (Cu), or a mixture of at least two of them. Can be formed.

A screen printing method according to an embodiment of the present invention prepares a screen mesh 13 having a plurality of through holes 14, fills a part of the through holes 14 of the screen mesh 13, and forms a mask portion 11. 11, a part of the through hole 14 is defined as the printing region 12. Then, the screen printing plate 10 is manufactured with the wall portion 20 in the printing region 12.

At this time, the printing region 12 can be formed on the mask portion 11 formed on the screen mesh 13 through a separate exposure or phenomenon process. For example, the printing region 12 is formed through a photolithographic process in which a photoresist is applied on the mask portion 11, the photomask is applied and exposed through UV or the like, and then the mask portion 11 is subjected to laser or dry etching. Can be used.

The wall portion 20 can be formed in the printing region 12 in the vertical direction by filling a part of the through hole 14 of the screen mesh 13 with an emulsion such as an emulsion. Further, the wall 20 may be formed while leaving a partial region of the corresponding mask portion 11 when the print region 12 is formed through a separate exposure or phenomenon process.

Such a wall portion 20 serves to prevent an increase in the filling amount of the conductive paste in the peripheral portion of the printing region 12. The distance between the wall portion 20 and the inner surface of the printing region 12 can be 30 to 100 μm corresponding to a region where the discharge amount of the conductive paste is large.

As a result, the screen printing plate 10 is provided on the ceramic green sheet 30 with a predetermined gap G, and a conductive paste is applied to or around the printing region 12 of the screen printing plate 10, and then a squeegee or the like is used. The internal electrode film 40 is printed on the ceramic green sheet 30 using a pressurizing means.

The conductive paste may include metal powder, ceramic powder, and silica (SiO ₂ ) powder. The metal powder may be Ni, Mn, Cr, Co, Al, or an alloy thereof, but is not limited thereto. The average particle size is preferably 50 to 400 nm.

The thickness of the internal electrode film 40 can be appropriately adjusted depending on the application, and is preferably in the range of 0.1 to 1.0 μm.

Accordingly, the conductive paste discharged to the printing region 12 is blocked from being injected by the wall portion 20 at the peripheral portion thereof, and the filling amount of the central portion and the peripheral portion of the printing region 12 becomes substantially equal. In particular, the wall portion 20 also serves as a blocking wall that suppresses the upper surface of the internal electrode film from protruding when the internal electrode film is formed by the conductive paste discharged at the periphery of the wall portion 20.

At this time, the conductive paste that passes through the printing region 12 of the screen mesh 13 is blocked by the wall portion 20, and the conductive paste does not pass at the corresponding position of the wall portion, and is printed while being supplied through the peripheral portion of the wall portion 20 The entire filling amount of the region 12 is adjusted, and the upper surface of the internal electrode film 40 can be formed substantially flat. At this time, the wall part 20 can also press the peripheral part of the internal electrode film 40 and can also prevent the peripheral part from protruding.

Thereafter, the ceramic green sheet 30 on which the internal electrode film 40 is formed is peeled off from the carrier film, and the plurality of ceramic green sheets 30 on which the carrier film has been peeled are pressure-bonded at high temperature and high pressure to be laminated, from tens to hundreds of layers. It is preferable to manufacture a green ceramic laminate that is laminated in a bar shape and highly laminated.

Next, the green ceramic laminated body is cut into a predetermined size through a cutting process to manufacture a green chip. Thereafter, through steps such as calcination, firing, polishing, and external electrode plating, a multilayer ceramic capacitor is finally completed.

At this time, firing is preferably performed at a high temperature of about 1100 ° C. or higher. This is because if a non-metal such as Ni is used as the internal electrode film 40, oxidation occurs from 400 ° C., which is a low temperature, sintering shrinkage occurs, and there is a risk of rapid firing at 1000 ° C. or higher.

If the internal electrode film 40 is rapidly fired, the electrodes may be agglomerated or cut off due to over-baking of the internal electrode film 40, and the connectivity and capacity of the internal electrode film 40 may be reduced. In addition, after firing, defects in the internal structure of the multilayer ceramic capacitor such as cracks may occur.

Therefore, it is necessary to minimize the difference in shrinkage from the dielectric by delaying the sintering start temperature of the metal powder that starts sintering at a relatively low temperature of about 400 to 500 ° C. to the maximum extent.

The present invention is not limited by the above-described embodiments and the accompanying drawings, but is limited by the appended claims. Accordingly, various forms of substitution, modification, and alteration can be made by persons having ordinary knowledge in the art without departing from the technical idea of the present invention described in the claims. Belongs to a range.

DESCRIPTION OF SYMBOLS 10 Screen printing board 11 Mask part 12 Print area 13 Screen mesh 14 Through-hole 20, 21, 22, 23, 24, 25, 26 Wall part 30 Sheet 40 Internal electrode film

Claims (16)

A screen mesh having a plurality of through holes;
A mask portion formed by filling a part of the plurality of through holes;
At least one print area defined by the mask portion;
A pair of wall portions opposed to each other at a predetermined interval from both peripheral portions of the print region;
Including screen printing board. The screen printing plate according to claim 1, wherein a distance between the wall portion and a peripheral portion of the printing region is 30 to 100 μm. The screen printing plate according to claim 1, wherein the pair of wall portions are arranged side by side. The screen printing plate according to claim 1, wherein the wall has a width of 5 to 20 μm. The screen printing plate according to claim 1, wherein the print area is formed in two or more rows on the screen mesh. The screen printing plate according to claim 5, wherein the printing areas of each row are arranged side by side. The screen printing plate according to claim 6, wherein the second print area in the second row adjacent to the first print area in the first row is arranged to be shifted from each other. 2. The screen according to claim 1, wherein the wall portion is formed to be higher and lower than the printing area, and the end portion of the wall portion facing the sheet and one surface of the mask portion are formed to have a step. Printing board. The screen printing plate according to claim 1, wherein the wall portion is formed with a bulging end toward the sheet. The screen printing plate according to claim 1, wherein the wall portion is formed with a recessed end toward the sheet. 2. The screen printing plate according to claim 1, wherein the wall portion is formed to have different lengths on the left and right sides of an end portion facing the sheet. The screen printing plate according to claim 1, wherein the wall portion has an uneven portion at an end toward the sheet. A screen printing plate having at least one printing area is disposed on the sheet, a conductive paste is supplied to the printing area to form an internal electrode film on the sheet, and a predetermined distance from both peripheral portions of the printing area A method of manufacturing a multilayer ceramic capacitor, wherein a part of the conductive paste is cut off by a pair of wall portions arranged with a gap therebetween. A surface having the same height as that formed in the portion without the wall portion by a conductive paste that has passed through the open through hole around the wall portion at a position corresponding to the wall portion of the sheet. The method of manufacturing a multilayer ceramic capacitor according to claim 13, wherein the internal electrode film is formed so as to have the inner electrode film. The method of claim 13, wherein the screen printing plate is provided at a predetermined distance from the upper surface of the sheet. A multilayer ceramic capacitor produced by the production method according to claim 13.

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