JP2007332025A - Blackish free-cutting ceramic, and production method and application of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic which has a free-cutting property, in which a thin-walled deep hole or a slit can be thereby formed with good precision and which can be used for a probe guide for high density LSI inspection, and further, which is uniformly blackened so that the inspection of a processed shape or aligning using an image processing apparatus is not intercepted by reflection light and has a low coefficient of thermal expansion. <P>SOLUTION: The ceramic is obtained by adding zirconia in an amount of 0.1-20 mass%, based on aggregate, to a raw material powder containing, as the aggregate, 25-60 mass% silicon nitride and 40-75 mass% boron nitride, and a sintering aid, and firing the resulting mixture in a reducing atmosphere. The ceramic is blackened by the reduction of the zirconia during firing. This blackening method can be utilized for the blackening of other ceramics. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a ceramic colored in a black color, in particular, a free-cutting ceramic and a method for producing the same. This black free-cutting ceramic is capable of high-strength and fine machining and absorbs light, so that light reflection is suppressed. Therefore, it is possible to accurately perform measurement such as image processing measurement without performing coloring processing, and by such measurement, an insulating microfabricated part that performs dimension measurement and alignment of a processed shape, for example, semiconductor inspection It is optimal as a material for probe guides used in devices. By machining the ceramic of the present invention, it is possible to easily and stably manufacture a micro-machined part with high machining accuracy without lowering the dimensional accuracy due to the coloring process. This improves the reliability of semiconductor inspection equipment.

  Ceramic materials are excellent in mechanical characteristics and high temperature characteristics, and therefore can be used for insulating structural members for semiconductor manufacturing equipment. However, since ceramics have a large shrinkage at the time of sintering, grinding is necessary to obtain a desired shape and dimensions with high accuracy, and in this case, difficulty in processing ceramics becomes a problem.

  In order to improve the workability of ceramics, there is known a material called free-cutting ceramics in which ceramics or other ceramics having a cleavage property in a glass matrix, such as mica or boron nitride, are dispersed, and are used for semiconductor inspection equipment. Although it is used as a material, few have excellent workability required for high-precision fine processing.

  As a part for a semiconductor manufacturing apparatus that requires high-precision fine processing and insulation, there is a probe guide (probe guide part) used in an inspection apparatus for inspecting electrical characteristics of a semiconductor element such as an LSI. This inspection apparatus includes a probe card provided with the same number of measurement probes as electrode pads formed on a semiconductor element to be inspected, and performs inspection by simultaneously bringing the probes into contact with the electrode pads.

  As shown in FIG. 1 (A), the probe card 1 is formed of an insulating material such as ceramics, and has an opening A that is larger than the semiconductor element to be inspected and is normally open in a morning glory shape at its center. On the upper surface of the probe card 1, the same number of metal measuring probes 2 as the electrode pads of the semiconductor elements are attached by, for example, an adhesive. The tip of the probe 2 is bent in a substantially L shape and protrudes from the lower surface of the card 1 through the opening A.

  When the probe card 1 is placed on the semiconductor element to be inspected and pressed, the tip of the measurement probe 2 protruding from the opening A comes into contact with an electrode pad (not shown) of the semiconductor element, and the electrical characteristics of the semiconductor element are Inspected. In order to do so, a large number of measuring probes must all be in contact with the electrode pads at the same time. However, the tip of a thin metal probe is likely to be displaced due to bending at the time of pressing, and reliable contact with the electrode pad becomes difficult.

  In order to facilitate precise positioning of the measurement probe, as shown in FIG. 1 (B), a probe guide 3 having a through hole B through which the probe passes through a plate of insulating material in the same pattern as the electrode pad is provided as a probe card. 1 so as to close the opening A. Thereby, since the tip of each probe 2 protrudes through the through hole B of the probe guide 3, the lateral movement due to the bending is limited, and the probe 2 can be reliably brought into contact with the electrode pad.

  The probe guide 3 needs to be formed with through holes B having a diameter slightly larger than that of the measurement probe 2 at the same pitch as the electrode pads. Recent LSIs have dramatically increased in density, and it is not uncommon for the pitch of electrode pads to be 100 μm or less. For example, as shown in Fig. 1 (C), if the electrode pad pitch is 70μm and the diameter of the through hole B is 60μm, the wall thickness between the through holes (minimum distance between the holes) will be 10μm. Becomes very thin. It is necessary for the probe guide to form such a fine and thin through hole with high accuracy by, for example, drilling.

  Conventional probe guides are made of plastic or have been made from a free-cutting crystallized glass ceramic material as proposed in US Pat. However, the plastic cannot be used when it is necessary to inspect at a high temperature, and sufficient dimensional accuracy of the through hole cannot be obtained. When a crystallized glass ceramic material is used, it is possible to cope with a high-temperature inspection, but there is a problem that a thermal expansion coefficient is larger than that of a semiconductor element and a positional deviation occurs depending on a measurement temperature. Moreover, since the strength of the material is low, chips and cracks are likely to occur during drilling, and sufficient dimensional accuracy cannot be obtained.

  The conventional probe guide made of crystallized glass ceramics has another problem that the color is whitish. When the probe guide color is white, it is easy to reflect light during dimensional inspection of through holes formed by microfabrication or when performing image processing measurements for alignment when the probe guide is attached to the probe card. Accurate measurement becomes difficult. In addition, dirt is also conspicuous in appearance, and the product value is reduced due to the dirt. Therefore, it is preferable that a part to which image processing measurement is applied at the time of dimensional inspection or alignment, such as a probe guide, has a black appearance with low reflectivity and inconspicuous dirt.

As a method for coloring ceramics, Patent Document 2 describes that a small amount of transition metal oxide such as chromium oxide, nickel oxide, cobalt oxide, manganese oxide is mixed. Further, Patent Document 3 describes that when a ceramic containing 95% or more of zirconia is reduced, it is blackened by deoxidation.
JP 58-165056 A JP 63-139505 A JP 63-236761

  The present invention combines a machinability that can be easily machined, suitable as a material for a probe guide, and a high strength that does not cause cracking or chipping during machining such as drilling, and has a blackish low reflectivity. It is an object to provide a high-strength black free-cutting ceramic having an appearance and a method for producing the same.

  The inventors of the present invention have previously disclosed a ceramic that has been sintered by mixing a sintering aid in a main component composed of 25 to 60% by mass of silicon nitride and 40 to 75% by mass of boron nitride. The inventors have found that they can be machined with high precision that has never been obtained before and filed a patent application (Japanese Patent Application No. 11-133341).

Using this nitride-based free-cutting ceramic, not only can a thin through-hole shown in Fig. 1 (C) be formed without cracking or chipping by drilling, but also as shown in Fig. 1 (D). Furthermore, a thin and deep slit having a wall thickness of 5 to 20 μm and a depth of 15 times the wall thickness or more can be accurately formed by grinding with a grindstone (with a pitch accuracy between slits within ± 4 μm). By making such a fine slit processing possible, as shown in FIG. 1 (E), a slit-type probe guide in which the movement of the probe is limited by a slit instead of a through hole can be realized. This ceramic has a low thermal expansion coefficient of 3 × 10 ⁻⁶ / ° C. or less at 25 to 600 ° C., so that the difference in thermal expansion coefficient from the semiconductor element is small and there is no fear of causing a positional shift.

  As described above, the above-described free-cutting ceramic has ideal characteristics as a material for a microfabricated part for a semiconductor manufacturing apparatus such as a probe guide, but the same color as described for the glass ceramic described above. The problem of being white and having high light reflectivity remained. Thereby, it becomes difficult to perform microscopic dimension inspection using image processing measurement and alignment with a probe card.

  Therefore, blackening of this nitride-based free-cutting ceramic was examined. First, as a simple method, it is conceivable to finely process the shape of the probe guide and then deposit black metal or ceramics or coat it with a resin film in black. However, it has the disadvantage of being easy to peel off, and even if the coating itself is thin, it has a thickness of nearly 10 μm, and it is difficult to obtain a uniform film thickness, which hinders maintaining accuracy. In the case of a resin film, there is also a problem that it cannot be used at a high temperature. Therefore, blackening by coating has many problems, and it is desirable to blacken the ceramic itself.

  Of the known methods for coloring ceramics, the above-mentioned nitride-based free-cutting ceramics were colored by mixing a small amount of transition metal oxides such as chromium oxide and cobalt oxide. Concentric color unevenness centering on the center of the body is prominent, resulting in a decrease in commercial value and inaccurate image processing measurement. When a large amount of coloring components are added to darken the color, mechanical properties such as breaking strength are deteriorated, which adversely affects workability.

  Therefore, as a result of examining another method for coloring ceramics, it was found that when zirconia was added to the raw material powder and fired in a reducing atmosphere, the zirconia was reduced and the ceramics were colored black. When this coloring method is used, the above-mentioned nitride-based free-cutting ceramic can be colored relatively uniformly in a black color even if the amount of zirconia added is small.

  Here, the black type includes gray, dark blue and dark purple. It has also been found that this coloring method using reduction during firing of zirconia is applicable not only to the above-mentioned nitride-based free-cutting ceramics but also to blackening of white ceramics in general. The reason why white ceramics can be uniformly colored black by zirconia has not been completely elucidated, but is presumed to be related to the fact that Zr oxides are more easily reduced than Cr and Co.

  In blackening using zirconia, even if the addition amount is small, it can be uniformly colored, so uniform blackening is possible without degrading the machinability, and the addition of zirconia itself is a high-strength ceramic material. It has also been found that increasing the amount to some extent does not adversely affect the strength of the nitride ceramic.

In the present invention, zirconium and / or an oxide thereof is 0.1 to 20 parts by mass in terms of ZrO ₂ with respect to 100 parts by mass of the main component consisting of 25 to 60% by mass of silicon nitride and 40 to 75% by mass of boron nitride. It is a black free-cutting ceramic characterized by containing. Here, the black color is a blackish color including black, gray, dark blue, and dark purple as described above.

  This black free-cutting ceramic includes a step of using a raw material powder containing silicon nitride, boron nitride, zirconia and a sintering aid, and firing the raw material powder in a reducing atmosphere. , Can be manufactured.

As described above, the blackening of ceramics utilizing the reduction of zirconia can be applied to the blackening of white ceramics in general. Therefore, in a broader sense, according to the present invention,
-Black ceramics characterized by containing zirconium and / or oxides thereof in a proportion of 20 parts by mass or less in terms of ZrO ₂ with respect to 100 parts by mass of the main component ceramics; and-Ceramic raw materials added with zirconia A method for producing black ceramics, comprising a step of firing the powder in a reducing atmosphere,
Is also provided.

  Also, a ceramic probe guide having a plurality of slits and / or holes through which the probe passes, wherein the ceramic is the above-mentioned black free-cutting ceramic, and the slits and / or holes are formed by machining Also provided is a probe guide characterized in that it is.

  Since the black free-cutting ceramics of the present invention can accurately form deep slits or through-holes with a thin wall thickness and a small width or diameter, a probe guide that holds the probe in a predetermined position at a high density is manufactured from the ceramics. Is possible. In addition, since this ceramic is uniformly blackened to the inside, the image processing measurement inspection of the processed shape can be performed smoothly without being disturbed by reflected light, and since the thermal expansion coefficient of the ceramic sintered body is small, the temperature Since the positional deviation due to the change is less likely to occur, the reliability of the inspection apparatus is greatly increased. As a result, it is possible to realize a semiconductor element inspection apparatus that can cope with higher density of LSI. Furthermore, since the color tone is inconspicuous, the commercial value is unlikely to decrease.

  Further, the blackening of ceramics using reduction during firing of zirconia according to the present invention does not use the reaction between zirconia and a ceramic raw material, but is blackened by reduction of zirconia itself. It can be applied to ceramics in general and its application range is wide.

The black free-cutting ceramic according to the present invention is used as a blackening agent for 100 parts by mass of a main component (hereinafter referred to as aggregate) composed of 25 to 60% by mass of silicon nitride and 40 to 75% by mass of boron nitride. It contains 0.1 to 20% by mass of zirconium and / or its oxide. Zirconium as a blackening agent is added to the raw material powder as zirconia (ZrO ₂ ). Zirconia itself is white, but during the reduction in firing in a reducing atmosphere, the crystal structure changes to an oxygen-deficient type or becomes black due to reduction to metal zirconia, so the entire ceramic Exhibits a blackish color tone.

  This black free-cutting ceramic can be manufactured by the following method. First, a raw material powder is prepared by mixing a sintering aid component and zirconia in a powder state with an aggregate composed of 25 to 60% by mass of silicon nitride and 40 to 75% by mass of boron nitride. This mixing can be performed by, for example, a wet ball mill.

  If the proportion of silicon nitride in the ceramic aggregate exceeds 75% by mass, the machinability of the ceramic deteriorates, and if it falls below 25% by mass, the strength of the ceramic decreases. It becomes difficult. The proportion of silicon nitride is preferably 30 to 60% by mass.

  The boron nitride is preferably a hexagonal system (h-BN) having a graphite structure. From the standpoint of obtaining the high strength required during microfabrication, the aggregate powder, particularly boron nitride powder, preferably has an average particle size of less than 1 μm.

  The sintering aid can be selected from those conventionally used for sintering silicon nitride and boron nitride. Preferred sintering aids are one or more derived from complex oxides such as aluminum oxide (alumina), magnesium oxide (magnesia), yttrium oxide (yttria), and lanthanoid metal oxides and spinels, More preferred is a mixture of alumina and yttria, or a mixture obtained by further adding magnesia.

  The blending amount of the sintering aid is desirably in the range of 1 to 15 mass%, particularly 3 to 10 mass% of the aggregate powder composed of silicon nitride and boron nitride. If the blending amount is too small, the sintering becomes insufficient, and the strength of the ceramic ceramic, which is a sintered body, decreases. If the blending amount is too large, the low-strength grain boundary glass layer increases, which also causes a decrease in the strength of the ceramic. .

Zirconia (ZrO ₂ ) added as a blackening agent is blended at a ratio in the range of 0.1 to 20 parts by mass with respect to 100 parts by mass of the aggregate powder composed of silicon nitride and boron nitride. In general, the strength of blackening of the ceramic after firing changes according to the amount of zirconia. If the blending amount is less than 0.1 parts by mass, a sufficient blackening effect due to reduction of zirconia is hardly obtained. If the blending amount is more than 20 parts by mass, the machinability of the ceramic is lowered and fine processing cannot be performed with high accuracy. The amount of zirconia is preferably 0.1 to 5 parts by mass. In this range, particularly fine slits and holes can be processed with high accuracy.

  Zirconia added as a blackening agent may act as a sintering aid, but in the present invention, zirconia is excluded from the sintering aid. In addition, if the amount of the sintering aid and zirconia is too large, the proportion of aggregate is relatively reduced, the strength of the ceramic is lowered, and the precision of microfabrication may be lowered. The total amount of the agent and zirconia is preferably 20 parts by mass or less, more preferably 15 parts by mass or less with respect to 100 parts by mass of the aggregate.

Zirconia is used as a black agent may be a powder of ZrO ₂ plain but, Y ₂ O ₃ in ZrO ₂ as a stabilizer, CeO _2, MgO, by adding at least one such CaO, stabilized or partially stabilized Zirconia powder may be used.

  Addition of zirconia should also be performed using zirconia or the above-mentioned stabilized or partially stabilized zirconia as the mixing container (pot) and / or mixing medium (ball) when mixing the raw material powder with a ball mill or the like. Therefore, it can also be performed by mixing zirconia into the raw material powder due to wear of these containers and media. However, if the amount of zirconia is 1 part by mass or more with respect to 100 parts by mass of aggregate, for example, it takes a very long mixing time to add the necessary amount of zirconia due to this wear mixing, which is not practical. When using the introduction of zirconia due to abrasion, it is preferable to use zirconia from the outside as well. In that case, the amount of wear of zirconia under a constant mixing condition is examined in advance by experiments, and an insufficient amount of zirconia may be added from the outside.

  The raw material powder adjusted to a predetermined composition is fired and sintered to obtain ceramics. In the present invention, since it is necessary to reduce at least a part of zirconia for blackening with zirconia, calcination is performed in a reducing atmosphere, and zirconia is reduced during calcination. Firing is preferably performed under pressure in order to obtain a high-strength, dense ceramic.

  The reducing atmosphere may be at atmospheric pressure, increased pressure, or reduced pressure. The reducing atmosphere is obtained, for example, by arranging a carbon member in a furnace, filling or arranging raw material powder or a molded product thereof in a carbon jig, and / or using a carbon heater as a heating means. Convenient.

  The reducing atmosphere can be a hydrogen-containing gas atmosphere such as hydrogen gas or a mixed gas of hydrogen and nitrogen generated by the decomposition of ammonia, instead of using carbon.

The firing temperature is preferably in the range of 1700-1950 ° C. If the temperature is too low, sintering will be inadequate, and reduction blackening of ZrO ₂ will not occur. If it is too high, the aggregate, which is the main raw material, will thermally decompose.

  Firing can be performed using a hot press which is a high-temperature pressure sintering method. In this case, the pressure is suitably in the range of 20-50 Mpa. The duration of hot pressing is usually about 1 to 4 hours, although it depends on the temperature and dimensions. High temperature pressure sintering can also be performed by HIP (hot isostatic press). Sintering conditions in this case can be appropriately set by those skilled in the art.

The nitride ceramics produced in this way have a coefficient of thermal expansion of 3 × 10 ⁻⁶ / ° C. or less at 25 to 600 ° C. if the type and amount of the sintering aid are appropriately selected. The difference in coefficient of thermal expansion is small and misalignment is less likely to occur when used as a probe guide. Since this ceramic has excellent machinability and high strength, fine slits or holes can be machined with high precision, and the interior is colored uniformly in black, so the surface remains black after machining. It has a system and has less light reflection at the time of optical shape measurement such as image processing measurement, so that the measurement can be performed smoothly, dirt is not conspicuous, and the appearance is excellent.

  The ceramic of the present invention is preferably in a plate shape. A plurality of through holes as shown in FIG. 1 (C) or a plurality of slits as shown in FIG. 1 (D) are formed from this plate-like ceramic by drilling with a drill or slitting with a grinding wheel. Guides can be made. Of course, the application of the ceramic of the present invention is not limited to the probe guide. It is useful for various applications where insulation, high strength and free-cutting properties are required, and black is desirable.

By using the black free-cutting ceramic of the present invention, a probe guide having the following shape and accuracy of drilling or slitting can be manufactured:
Drilling hole diameter: 65μm or less,
Wall thickness between holes: 5-20 μm,
Hole depth / wall thickness ratio: 15 or more,
Hole diameter and hole pitch accuracy: within ± 4μm.

Slit processing Wall thickness: 5-20μm,
Depth / wall thickness ratio: 15 or more
Pitch accuracy between slits: Within ± 4 μm.

  Since the ceramic of the present invention has good machinability and high strength, it is possible to finely process deep holes and slits with a thin wall thickness into an accurate shape without causing cracks or chips during processing. . Accordingly, a probe guide that can hold the probe at a high density and has improved probe positioning accuracy is manufactured, and the reliability of the inspection apparatus is increased.

  Although the present invention has been described above for blackening of free-cutting ceramics mainly composed of silicon nitride and boron nitride, the present invention can be used to impart a black color tone to other white ceramics. You can do it. Examples of such white ceramics include alumina, magnesia, boron nitride, and composite materials containing one or more of these.

  In this case as well, the type and amount of zirconia added as a blackening agent may be the same as described above, and the degree of blackening of the ceramic after firing tends to depend on the amount of zirconia added. It is necessary for blackening that firing is performed in a reducing atmosphere as well, and at least a part of zirconia is reduced during firing. The firing temperature may be appropriately set according to the type of ceramic or sintering aid. The molding method can be selected from a wide range of methods depending on the application. In applications where densification of ceramics is not important, a wet forming method such as a slip casting method may be used.

  Below, the Example and comparative example regarding the black type free-cutting ceramics which concern on this invention are shown. Unless otherwise specified,% and part in Examples and Comparative Examples are% by mass and part by mass.

(Examples 1-3)
Obtained by mixing hexagonal boron nitride (h-BN) powder with an average particle size of 0.5 μm and purity of 99% and silicon nitride powder with an average particle size of 0.2 μm in the ratios shown in Nos. 1 to 3 in Table 1. To 100 parts of the aggregate powder, 2 parts of alumina and 6 parts of yttria were added as sintering aids, and wet ball mill mixing was performed using ethyl alcohol as a solvent.

  Ball mill mixing was performed in a polyethylene pot using partially stabilized zirconia balls containing 3 mol% itria as the mixing medium. The mixing time was adjusted so that the amount of zirconia mixed from the ball was 0.5%, and the partially stabilized zirconia powder containing 3 mol% yttria was preliminarily adjusted so that the total amount of zirconia mixed together was 2%. It has been added to the ball mill.

  The slurry obtained by mixing with the ball mill was dried with a vacuum evaporator to remove ethanol, and a raw material powder for firing was obtained. This raw material powder is filled in a graphite die, and hot press sintering is performed at 1850 ° C. for 2 hours while applying a pressure of 30 Mpa in a nitrogen atmosphere, and a plate-like ceramic sintered body of 65 × 65 mm and 10 mm thickness is fired. A ligature was obtained. In this case, the firing atmosphere becomes a reducing atmosphere due to the presence of graphite in the die. The appearance of the obtained sintered body has a gray color tone, and it has been proved that the ceramic is blackened by firing in a reducing atmosphere even when containing a small amount of zirconia of 2% of the aggregate.

  A test piece was cut out from the sintered body, and the fracture strength was measured by a three-point bending test. Also, in order to evaluate machinability, a turning test was conducted using a carbide-K10 type tool at a grinding speed of 18 m / min, a feed rate of 0.03 mm / rev, and a cutting depth of 0.1 mm. The surface roughness of the cutting material and the flank wear width of the tool (indicating the degree of tool wear) were measured. The smaller these values, the better the machinability. Furthermore, the thermal expansion coefficient of this sintered body was measured in the range of room temperature (25 ° C.) to 600 ° C.

  After cutting this sintered body into a thin plate with a thickness of 300 μm, using a carbide drill (material SKH9) with a diameter of 50 μm, as shown in FIG. A total of 200 holes) were drilled. The diameter of the hole is 60 μm and the depth is 300 μm.

  Measure the accuracy of the hole diameter and hole pitch of the obtained through-hole, and if this accuracy is within ± 4μm and there is no crack or chipping, drilling is possible, but the accuracy is insufficient, The case where chipping occurred was evaluated as Δ, and the case where drilling was not possible due to breakage of the drill was evaluated as ×.

  In addition, a slit (width = 40 μm, wall thickness) shown in FIG. 1 (D) is formed on this sintered body by slitting using a grinding wheel (resin bond diamond wheel # 200, thickness 40 μm, outer diameter 50 mm). = 15 μm, depth = 300 μm).

  Slit processing is possible, but the accuracy is insufficient (pitch accuracy exceeds ± 4μm) or cracks and / or chipping (chipping) occurs △, slit processing with sufficient accuracy is possible. The case where no chipping occurred was evaluated as ◯.

  About the ceramic sintered compact which gave the above-mentioned slit and hole processing, the presence or absence of the color unevenness (coloring uniformity) of the surface including a process part was inspected by visual observation. If it was uniformly colored, it was rated as ◯, and if there was unevenness, it was marked as x.

  If the color tone is also inspected, and the image processing measurement of the processed shape (hole diameter, hole processing-position, etc.) can be performed smoothly, the degree of blackening ○, the case where the measurement could not be performed smoothly due to light reflection, etc. It was.

  The above survey results are summarized in Table 1. FIG. 2 shows an example of a scanning electron micrograph showing the surface when a sintered body having a mass ratio of silicon nitride: boron nitride of 40:60 is drilled.

(Examples 4 to 6)
Ceramic sintered bodies were prepared in the same manner as in Examples 1 to 3, but in this example, the mass ratio of silicon nitride: boron nitride was kept constant at 30:70, and the amount of partially stabilized zirconia added to the ball mill was changed. In addition, the powder mixed with wear from the balls was combined to obtain a raw material powder having a zirconia content shown in Table 1. The results of investigating the fracture strength, machinability, thermal expansion coefficient, slit and drilling, color tone, and blackening degree of the obtained sintered body in the same manner as in Examples 1 to 3 are also shown in Table 1. In any case, the color tone of the sintered body was the same as in Examples 1 to 3, but the color intensity changed according to the content of zirconia.

(Comparative Examples 1 and 2)
Sintered bodies were produced in the same manner as in Examples 1 to 3, except that the mass ratio of boron nitride powder and silicon nitride powder was outside the scope of the present invention.

(Comparative Examples 3 and 4)
The mass ratio of silicon nitride: boron nitride was constant at 40:60, and the zirconia content was varied outside the scope of the present invention. In Comparative Example 3, the raw material powder was prepared so that the total amount of zirconia mixed including the wear mixed powder from the balls during mixing was 25% by mass. In Comparative Example 4, the mixing time was adjusted so that the zirconia wear-mixed powder during ball milling was 0.05% by mass, and zirconia powder was not added. The raw material powder was fired in the same manner as in Examples 1 to 3 to obtain a sintered body.

(Comparative Example 5)
In the same manner as in Example 1, a sintering aid was added to an aggregate powder having a mass ratio of silicon nitride: boron nitride of 40:60. As a coloring agent, molybdic acid (H ₂ MoO ₄ ) was added in an amount such that Mo becomes 0.1 part with respect to 100 parts of the aggregate powder, and a nylon ball was used as a mixing medium in a polyethylene pot. Then, they were mixed by a wet ball mill and dried to obtain a raw material powder. This raw material powder was fired in the same manner as in Examples 1 to 3 to obtain a sintered body.

  For the ceramic sintered bodies of Comparative Examples 1 to 5 above, the results of investigating the breaking strength, machinability, thermal expansion coefficient, slit and drilling, color tone, and degree of blackening in the same manner as in Examples 1 to 3 were obtained. It shows together in Table 1.

(Comparative Example 6)
As a conventional probe guide material, an Al ₂ O ₃ —SiO ₂ —K ₂ O-based free-cutting crystallized glass ceramic material plate was prepared. This conventional material was also subjected to drilling and slitting similar to those described in Examples 1 to 3, but the strength of the material was weak, and when fine processing was performed, as shown in FIG. ) Occurred, and it was not possible to drill holes accurately and accurately. In addition, this conventional material is white and it is difficult to measure the hole position due to light reflection during image processing measurement. The survey results other than the coloring of the conventional material are also shown in Table 1.

  As can be seen from Table 1, the conventional glass ceramic material has a remarkably large thermal expansion coefficient and a low strength. For this reason, it is easily chipped by drilling and cannot be drilled cleanly.

  In contrast, the nitride ceramic of the present invention has a small coefficient of thermal expansion. And, if the mass ratio of the silicon nitride: boron nitride in the aggregate is in the range of 25: 75-60: 40, high strength and good machinability will result, so there will be no cracking or chipping and high precision Can be finely processed. Furthermore, by blending zirconia in an amount within the range of 0.1 to 20 parts with respect to 100 parts of aggregate, the reduction of zirconia during firing reduces the machinability and does not adversely affect the machinability. Ceramics are obtained. Therefore, the ceramic of the present invention is optimal as a processing material for a member having a thin wall and a high density of deep holes and slits, such as a probe guide.

  However, when the mass ratio of the silicon nitride and boron nitride in the aggregate and the blending amount of zirconia were too large, at least one of strength and machinability decreased. When the amount of zirconia was too small, the blackening was uniform, but the degree of coloring was insufficient, making image processing measurement difficult. When the colorant was other than zirconia, the coloration was uneven.

1A is an explanatory view showing a cross section of the probe card, FIG. 1B is an explanatory view showing a cross section of the probe card having the probe guide, and FIG. 1C is an upper surface (left side) of the through hole of the probe guide. Fig. 1 (D) is an explanatory diagram showing a fine slit shape that can be processed with the ceramic of the present invention, and Fig. 1 (E) is an explanatory diagram of a probe guide having a slit. It is. It is a scanning electron micrograph which shows the surface after drilling of the ceramics of this invention. It is a scanning electron micrograph which shows the surface after the drilling process of the conventional glass ceramics.

Claims (4)

Containing zirconium and / or an oxide thereof in a proportion of 0.1 to 20 parts by mass in terms of ZrO ₂ with respect to 100 parts by mass of the main component consisting of 25 to 60% by mass of silicon nitride and 40 to 75% by mass of boron nitride. Characteristic black-type free-cutting ceramics.   2. The method for producing a black free-cutting ceramic according to claim 1, comprising a step of firing a raw material powder containing silicon nitride, boron nitride, zirconia and a sintering aid in a reducing atmosphere. A black ceramic, comprising zirconium and / or an oxide thereof in a proportion of 20 parts by mass or less in terms of ZrO ₂ with respect to 100 parts by mass of the main component ceramic.   4. The method for producing a black ceramic according to claim 3, further comprising a step of firing the ceramic raw material powder to which zirconia is added in a reducing atmosphere.

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