JPH0699201B2 - Aluminum nitride sintered body having a sealed portion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to an aluminum nitride sintered body having a sealing portion, and more specifically, a conductive metallized layer formed on the sealing portion. The present invention relates to an aluminum nitride sintered body which has good adhesion between a sintered body and a base material of the sintered body, and is particularly useful as an envelope for a power tube, an oscillation component for a magnetron, an insulating tube for a laser tube, and the like.

(Prior Art) Aluminum nitride (AlN) sintered body has thermal conductivity, insulation,
Since it has excellent thermal shock resistance and high frequency characteristics and high strength at high temperature, it has recently attracted attention as a material for various electronic and electric parts.

By the way, among such AlN sintered body parts, for example, envelopes for power tubes, magnetron oscillation parts, insulating tubes for laser tubes, etc., are cylindrical AlN sintered bodies, and,
One end or both ends thereof are sealed with a metal member, for example. By the way, conventionally, these components have generally been formed of oxide-based ceramics sintered bodies such as alumina (Al ₂ O ₃ ) and beryllia (BeO). However, since all of these parts are required to have excellent heat dissipation properties and, in some cases, high frequency characteristics, Al ₂ O having insufficient thermal conductivity and high frequency characteristics.
₃ and, while satisfying these properties, AlN has been proposed as a toxic and expensive alternative to BeO.

A cylindrical component having a sealing portion made of an AlN sintered body may have a conductive metallized layer for joining a sealing member made of, for example, a metal by brazing or soldering on the sealing surface. is necessary. However, when a conductive metallization layer is formed on the surface of an AlN sintered body, the morbutene-manganese (Mo) that was applied to Al ₂ O ₃ and BeO described above is used.
-Mn) method cannot be applied as it is. On the other hand, Al
A metallized layer can be formed on the surface of the N sintered body by the direct bond copper method (DBC method) or a thick film method which has been conventionally known as a metallized method. However, this metallized layer is different from the AlN sintered body at high temperature. However, there is an inconvenience that the reliability of brazing or soldering, that is, the reliability of the joint portion for a long period of time is not sufficient because of low adhesion.

(Problems to be Solved by the Invention) As described above, the AlN sintered body is extremely useful as a material for the power tube envelope, the magnetron oscillating component, the laser tube insulating tube, and the like in view of its characteristics. However, since the quality of the conductive metallized layer formed in the sealing portion is not yet satisfactory, the present situation is that the application to the above-mentioned components is hindered.

The present invention solves the above conventional problems, and is a cylindrical AlN sintered body having a sealing portion, the adhesion between the conductive metallized layer formed in the sealing portion and the AlN sintered body base material Is good, for example, brazing a sealing metal or the like to the metallized layer, high bonding reliability when soldering, and since it is possible to maintain good airtightness in the sealed portion after sealing,
The purpose is to provide an AlN sintered body that is useful as each of the above-mentioned parts.

[Structure of the Invention] (Means for Solving the Problems) The present inventors have mainly focused on the combination of constituent elements of the metallized layer formed on the surface of the sealed portion of the AlN sintered body base material. As a result of repeated intensive studies, a specific combination that can achieve the above object was found, the effect thereof was confirmed, and the present invention was completed.

That is, in the cylindrical aluminum nitride sintered body having the sealed portion of the present invention, the conductive metallization layer formed in the sealed portion is (i) (i) molybdenum, tungsten and tantalum (first group). At least 1 selected from
And (ii) at least one selected from the group (second group) consisting of Group III element, Group IVa element, rare earth element and actinide element of the Periodic Table as a constituent element of the constituent phase A layer made of an alloy containing at least one group IVa element of the Periodic Table, or (c) at least one selected from the group consisting of (i) molybdenum, tungsten and tantalum; and (Ii) The layer is characterized in that it is a layer containing at least one of the elements constituting the sintering aid used in the production of the aluminum nitride sintered body as a constituent element of the constituent phase.

First, the AlN sintered body of the present invention is a cylindrical sintered body having a sealed portion, that is, a hollow sintered body, and a conductive metallized layer is formed on the sealed portion at one end or both ends according to the purpose of use. It will be. In this cylindrical AlN sintered body, the surface on which the conductive metallized layer is to be formed is not particularly limited as long as it is the end portion, and for example, the outer peripheral surface or the end surface of the sintered body end is attached with a sealing member. It is preferably set appropriately according to the position. Furthermore, although the characteristics of the AlN sintered body itself are not particularly limited,
When applied to each of the above-mentioned applications, such as power tube envelopes, magnetron oscillation parts, and laser tube insulation tubes, high heat dissipation is required, so its thermal conductivity is 50w / m ・ k. The above is preferable.

Now, in the present invention, the conductive metallized layer is formed as the layer shown in (a), (b) or (c) described above.

First, in the metallized layer shown in (a), the elements belonging to the first group, namely, morbutene (Mo), tungsten (W) and tantalum (Ta) have excellent heat resistance,
In addition, it has a coefficient of thermal expansion approximately similar to that of the base material of the AlN sintered body, and is a component that contributes to the improvement of heat resistance and heat cycle characteristics of the metallized layer.

These constituent elements are contained in the constituent phase in one kind or in combination of two or more kinds. In that case, these elements exist, for example, as a simple substance of each element, as a compound or solid solution containing each element, or as a mixture of two or more kinds selected from these simple substances, compounds and solid solutions. Among these, as compounds, oxides, nitrides, carbides, oxynitrides, carbonitrides, carbonates of these elements,
Examples thereof include carbonitrides, borides, and silicides, and such compounds include, in addition to the above elements, at least one element belonging to the second group described later and / or an element other than the elements belonging to the second group. It may be a complex compound containing at least one kind. The same applies to the solid solution.

On the other hand, the elements belonging to the second group, that is, the elements of the periodic table
Group III elements (B, Al, Sc, Ga, In, Tl), Group IVa elements (Ti, Zr, Hf), rare earth elements (Y, La, Ce, Pr, Nd, P)
m, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and actinide elements (Ac, Th, Pa, U, Np, Pu, Am, Cm,
Bk, Cf, Es, Fm, Md, No, Lr) have excellent wettability with AlN in the metallization layer forming step described later, that is, the heating step, and adhere to the conductive metallization layer and AlN sintered body. It is an ingredient that contributes to the improvement of sex. Among the elements belonging to this second group, particularly preferable elements are Al, Ti,
Zr, Hf, Y, Ce, Dy, Th, Sm and the like.

These constituent elements are contained in the constituent phase in the form of one kind or a combination of two or more kinds similar to the constituent elements belonging to the above first group, and the existence state thereof is the same as above, for example, each element simple substance. Or as a compound or solid solution containing each element as listed above, or as a mixture of two or more kinds selected from these simple substances, compounds and solid solutions.

Further, in the present invention, the composition ratio of the elements belonging to the first group and the elements belonging to the second group is not particularly limited, and may be appropriately set depending on the type or combination of the elements used, For example, the ratio of the total of the elements belonging to the first group and the total of the elements belonging to the second group is the atomic ratio
It is preferably set to about 90:10 to 10:90.

The AlN sintered body having the conductive metallized layer (a) in the sealing portion is manufactured, for example, as follows.

That is, first, AlN powder and yttrium oxide (Y
₂ O ₃ ), calcium oxide (CaO), aluminum oxide (Al
₂ O ₃ ), lanthanum oxide (La ₂ O) and cerium oxide (Ce
O) and at least one sintering additive powder are mixed and molded to produce a cylindrical molded body, and then the molded body is sintered by an ordinary method to form a cylindrical AlN sintered body. Get a union.

Then, a paste or a liquid material containing an element selected from each of the first group and the second group is applied to the sealing surface of the cylindrical AlN sintered body. Specifically, this paste or liquid material is obtained by dispersing a simple substance of the above element or a compound powder in an adhesive such as ethyl cellulose or nitrocellulose. At this time, as the raw material powder, a simple substance powder of each of the above elements, or a conductive inorganic compound containing each element, that is, oxide, nitride, carbide, silicide, boride, oxynitride, carbonitride, boro Nitride,
Silicon nitride, hydride, chloride, fluoride, bromide, iodide, nitrate, nitrite, sulfate, sulfite, borate, phosphate, phosphite, carbonate, oxalate, chlorine An acid salt, a silicate, a hydroxide, an ammonium salt, or an inorganic compound or an organic compound (for example, an alkoxide or a sol-gel) which becomes conductive by firing can be used. In addition, it is desirable that the paste or liquid material contains 5% by weight or more of the total amount of the element selected from the first and second groups or the compound containing the element.

Then, as described above, the paste or liquid material is applied to the surface of the base material of the AlN sintered body, dried, and then subjected to heat treatment to form a metallized layer.
The heating temperature at this time is usually about 1100 to 1800 ° C, although it varies depending on the type and combination of the constituent elements. As the atmosphere gas, nitrogen gas, dry homing gas, wet homing gas, etc. can be used,
The treatment time is preferably set to about 0.5 to 2 hours.

Incidentally, as described above, instead of a method of forming an electrically conductive metallized layer after first manufacturing an AlN sintered body, after applying a paste to be the metallized layer to a molded body of AlN, the sintering temperature of AlN and It is also possible to apply a so-called co-sintering method, in which firing is performed at a temperature that satisfies both the formation temperatures of the metallized layer and sintering of AlN and formation of the conductive metallized layer are simultaneously performed.

Next, the conductive metallization layer shown in (b) is the IV
Group a elements, namely titanium (Ti), zirconium (Z
It is an alloy layer containing at least one of r) and hafnium (Hf). In such an alloy layer, IVa
The alloy components other than the group elements are not particularly limited, but those which form an alloy having good wettability with the AlN sintered body are preferable. Specifically, silver (Ag),
Copper (Cu), nickel (Ni), molybdenum (Mo), etc. can be mentioned, and these can be used alone or in an appropriate combination. Group IVa elements such as Ti are dispersed, for example, in an alloy composed of at least two kinds of alloy components described above without forming an alloy even if they form an alloy with an alloy component element other than the group IVa element. It may exist in a confused state. Of these, if at least a part of the alloy layer is a eutectic alloy, the obtained alloy layer is more advantageous because it wets well with the AlN sintered body at a lower temperature. Specific examples of such eutectic alloys include Ag and Cu or Mo.
An example is a combination of Ni, Ag, and Cu so that each has a eutectic composition. In addition, in such alloy,
The proportion of at least one of Ti, Zr, and Hf is not particularly limited, but is usually preferably about 1 to 10% by weight.

The conductive metallized layer (b) can be formed, for example, as follows.

That is, similarly to the above, the paste or the liquid containing the Group IVa element and other alloying component elements may be applied to the desired surface of the AlN sintered body and then fired. As the pressure-sensitive adhesive used at this time, the same ones as mentioned above can be mentioned. As the raw material powder, the above elemental element powder or the compound powder as described above can be used. Also,
Firing is preferably performed in vacuum or in an inert gas such as Ar, and the firing temperature is usually 800 although it varies depending on the type and combination of the constituent elements forming the alloy layer.
It is about 1000 ℃. Furthermore, in addition to the method of using such a paste or liquid material, a method of placing foils or powders of each alloy component element or both on an AlN substrate and firing it in the same manner as above may be adopted. it can.

Further, the co-sintering method can be applied, as in the case of the metallized layer shown in (a) above.

Finally, the conductive metallization layer shown in (c) is Mo, W
And at least one element selected from Ta; and at least one of the metal elements constituting the sintering aid used in the production of the AlN sintered body as a constituent element of the constituent phase. Mo, W and Ta are contained in the metallized layer in the same form as the layer shown in (a) above, or in combination of two or more. On the other hand, examples of the sintering aid include those listed above, and in the metallized layer shown in (c), the constituent metals of these sintering aids, that is, Y,
At least one selected from Ca, Al, La, Ce and the like is contained. These metal elements exist as a simple metal as described above, or as various compounds or solid solutions.

Also when forming the conductive metallization layer shown in (c), a raw material paste consisting of elemental elements or compound powders of the AlN sintered body is formed in the same manner as in (a) and (b) above. 1100-180 after applying on desired surface
The firing may be performed at a temperature of about 0 ° C. Now, assuming that the sintering aid used when the AlN sintered body is manufactured is Y ₂ O ₃ , the raw material paste may contain Y simple substance, YF, or Y ₂ O _3. . The content of the same metal element as the sintering aid contained in the conductive metallized layer represented by (C) is preferably 3 to 50% by weight, particularly preferably 10 to 20% by weight.

When a sealing member made of a metal is bonded to the sealing portion of the cylindrical AlN sintered body having the conductive metallizing layer on the sealing portion thus obtained, first, Ni is added to the conductive metallizing layer. Plating, etc., and then in homing gas,
The plated layer may be annealed at 600 to 850 ° C., and then brazing or soldering may be performed.

(Example) An insulating tube for a laser tube as shown in FIG. 1 was manufactured. That is, first, it contains 1% by weight of Y ₂ O ₃ as a sintering aid.
The AlN powder was molded by a conventional method and then sintered at about 1800 ° C. for about 1 hour to obtain a cylindrical AlN sintered body 1 having a through hole 1a in its axis. Next, conductive metallized layers 2 and 3 were formed on the outer peripheral surfaces of the sealed portions 1b and 1b at both ends of the AlN sintered body 1. This metallization process starts with Li ₂ M.
The weight ratio of oO ₄ powder, TiO ₂ powder and nitrocellulose is 3:
The mixture is mixed at 2:10 to prepare a raw material paste, the paste is applied to a predetermined surface of the sintered body 1, dried and then heat-treated in air, and then in H ₂ / N ₂ gas at about 1100 ° C. for 1 hour. It was carried out by heating.

After that, Ni plating is applied to this conductive metallized layer and this is annealed at about 800 ° C, and then Kovar (Fe-Ni
-Co alloy) sealing members 4 and 5 were brazed to the conductive metallized layers 2 and 3, respectively. After that, a helium leak test was performed on the sealed portions 1b and 1c, and it was confirmed that the leak rate did not change for a long time at a leak rate of 1 × 10 ⁻⁸ cc atm / sec or less and that the sealing property was good.

In this way, the insulating tube for laser tube made of AlN sintered body has high thermal conductivity and insulating property comparable to that of BeO which is a conventional material, and it is not toxic like BeO and its price is 1%. It has the advantage of being extremely inexpensive at 3-1 / 5. Moreover, the joint reliability at the sealing portion is high,
It also has excellent sealing properties.

Example 2 A power tube envelope as shown in FIG. 2 was manufactured. That is, first, Al containing 1% by weight of Y ₂ O ₃ as a sintering aid.
The N powder was molded by a conventional method and then sintered at about 1800 ° C. for about 1 hour to obtain a cylindrical AlN sintered body 11 having a through hole 11a in its axis. Then, the sealing portions 11b at both ends of the AlN sintered body 11 and
Conductive metallized layers 12 and 13 were formed on the outer peripheral surface of the region corresponding to 11b. This metallization process starts with Ag,
Cu and Ti powders were mixed in a weight ratio of 71: 27: 2 (Ag and Cu are eutectic compositions), and 100 parts by weight of this mixed powder was mixed with 30 parts by weight of methyl cellulose to prepare a raw material. A paste was prepared, and after coating the paste on a predetermined surface of the sintered body 11 and drying, the paste was heated to about 830 ° C. in Ar gas and held for about 5 minutes.

After that, Ni plating is applied to the conductive metallized layer, and this is annealed at about 600 ° C., and then the sealing members 14 and 15 made of Kovar are attached to the conductive metallized layer 12 and
Brazed to 13. Then, the sealing parts 11b and 11c
When a helium leak test was conducted, it was confirmed that the leak rate was 1 × 10 ⁻⁸ cc atm / sec or less and did not change for a long period of time, and that the sealing property was good.

Furthermore, this envelope for power tubes has an efficiency of about 10%, especially in the high frequency range, compared with the conventional one made of Al ₂ O _3.
It was confirmed to be rising. This is because the heat dissipation of AlN is A
Due to its much higher price than l ₂ O ₃ .

Example 3 An oscillation component for magnetron as shown in FIG. 3 was manufactured. That is, first, an AlN powder containing 1% by weight of Y ₂ O ₃ as a sintering aid was molded by a conventional method and then sintered at about 1800 ° C. for about 1 hour to form a cylindrical AlN having a through hole 21a in its axis. A sintered body 21 was obtained. Then, a conductive metallized layer 22 was formed in a region corresponding to the sealed portion 21b at one end of the AlN sintered body 21, that is, at one end surface of the AlN sintered body 21.

In this metallization step, first, a raw material paste is prepared by mixing Mo powder, Y ₂ O ₃ powder containing the same metal element as the above-mentioned sintering aid, and nitrocellulose in a weight ratio of 2: 1: 1. The paste was applied to a predetermined surface of the sintered body 21, dried, and then heated in N ₂ gas at about 1700 ° C. for 1 hour.

After that, Ni plating was applied to the conductive metallized layer and annealed at about 800 ° C., and then sealing members 23 made of Kovar were brazed to the conductive metallized layer 22, respectively.
After that, a helium leak test was performed on the sealed portion 21b, and it was confirmed that the leak rate was 1 × 10 ⁻⁸ cc atm / sec or less and did not change for a long period of time, and that the sealing property was good. The bonding strength of the sealing member 23 was 5 to 10 kg / mm ² when evaluated as tensile strength.

In this way, the oscillation member for magnetron made of AlN sintered body has improved efficiency especially in the high frequency range compared with the conventional material made of Al ₂ O ₃ and has extremely high heat dissipation, so it is a cooling fan. Alternatively, miniaturization of the fan is achieved.

In addition, in the present embodiment, the above-mentioned three kinds of parts are described as an example, but the applicable range of the cylindrical AlN sintered body having the sealing portion of the present invention is not limited to these, and for example, It is useful when applied to various parts such as an entrance window for a fusion klystron, which requires various excellent properties of an AlN sintered body and has a high sealing property.

[Effects of the Invention] As is clear from the above description, the aluminum nitride sintered body having the sealed portion of the present invention has a conductive metallized layer having a specific constituent phase and good adhesion, in the sealed portion. Since it is formed, for example, the joining reliability when joining a sealing member made of metal to this sealing portion is extremely high, and the sealing property of the sealing portion is also very good. Its industrial value is high when it is applied to various electronic / electrical parts that require body characteristics, that is, high heat dissipation, insulation and high frequency characteristics, and need to form a sealing portion.

[Brief description of drawings]

1 to 3 are longitudinal sectional views showing an embodiment of an aluminum nitride sintered body having a sealing portion of the present invention. 1, 11, 21 ... Cylindrical AlN sintered body, 1a, 11a, 21a ... Through hole, 1b, 1c, 11b, 11c, 21b ... Sealing portion, 2, 3, 12, 13, 22 ... Conductive metallized layer , 4, 5, 14, 15, 23 ... Sealing member.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Sato 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Stock company inside the Yokohama Yokohama metal factory (72) Inventor Hiro Sugawara 8-shin-Sugita-cho, Isogo-ku, Yokohama, Kanagawa Inside the Toshiba Yokohama Metal Factory (72) Inventor Masaei Nakanishi 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Stock Company Inside the Yokohama Yokohama Metal Factory (56) Reference JP-A-60-33280 (JP, A) JP-A-57-160984 (JP, A) JP-A-50-75208 (JP, A) JP-A-62-36090 (JP, A) JP-A-62-128990 (JP, A)

Claims (2)

[Claims] 1. An aluminum nitride sintered body having a sealing portion at least at one end thereof, and a conductive metallization layer formed on the sealing portion, wherein the conductive metallization layer comprises: (I) at least one selected from the group consisting of molybdenum, tungsten and tantalum (first group),
And (ii) a layer containing at least one selected from the group (second group) consisting of a group III element, a group IVa element, a rare earth element and an actinide element of the periodic table as a constituent element of the constituent phase (B) a layer made of an alloy containing at least one group IVa element of the periodic table, or (c) at least one selected from the group consisting of (i) molybdenum, tungsten and tantalum, and (ii) ) An aluminum nitride having a sealed portion, which is a layer containing at least one element constituting a sintering aid used in the production of the aluminum nitride sintered body as a constituent element of a constituent phase Sintered body. 2. The aluminum nitride sintered body according to claim 1, wherein at least a part of the alloy is a eutectic alloy.