JPS63236756A - Polycrystal artificial ruby and manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an artificial ruby used as a bonding capillary, an optical connector, a wire guide, or an ornament, and a method for manufacturing the same.

(Prior Art) Polycrystalline synthetic rubies have been used as carriers for gold wires connecting electrodes on the surface of semiconductor chips and fingers of lead frames.

Such polycrystalline artificial ruby was made by mixing aluminum oxide and chromium oxide with MgO, SrO, Y2O5, La2O5, etc. as sintering aids, and sintering it in a predetermined atmosphere after molding it. Since it is difficult to control and requires a large amount of sintering aid, after forming the mixture of aluminum oxide, chromium oxide and magnesium oxide,
A method of sintering at a temperature of 1,400 to 2,000° C. in a vacuum of 0-' Torr or more has been proposed in Japanese Patent Application Laid-Open No. 59-97572.

(Problems to be Solved by the Invention) The artificial ruby obtained by the conventional method described above has a large average crystal grain size, poor translucency, and a hardness of 200%.
As the voltage exceeds 0HV, there are problems in terms of workability and durability.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a mixture of 0.7 to 3 wtk of chromium oxide, 0 to 0.05 wt. of magnesium oxide, and the balance of aluminum oxide. Prepare a powder, add an organic binder to the mixed fine powder of the oxide, mold it into a predetermined shape, and give this molded body a 1280-13
After sintering at 50℃, 1300-1310℃ and 100℃
Hot isostatic pressing was applied under conditions of 0 to 2000 atm.

(Effect) By performing under the above conditions, the average crystal grain size is 2.0 μm.
Contains no coarse particles of 4 μm or more and has a bore diameter of 0.
．． Artificial rubies with excellent translucency of 1 μm or less, hardness, and bending strength are produced.

(Example) Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the method of the present invention in the order of steps. When decomposed, purity is 99.9
A chromium salt that becomes chromium oxide with a purity of 9 or higher and a magnesium salt that becomes magnesium oxide with a purity of 99.994 or higher when thermally decomposed after spray drying are prepared. To give a specific example, the aluminum salt is ammonium alum or aluminum ammonium carbonite hydroxide (^^C)I:NH4^j! COs (
OH) 2) is used, and the chromium salt is chromium nitrate Cr.
(NOs)s・9)20, and magnesium nitrate Mg(NOs)s・6H20 is used as the magnesium salt.

Then, the above polysalts are weighed and suspended in an aqueous solution in a resin pot containing a resin ball, dried by a spray drying method, and then thermally decomposed at a temperature of 500 to 800°C to produce aluminum oxide and chromium oxide. and magnesium oxide are uniformly mixed to obtain a mixed fine powder of oxide.

Then, this mixed fine powder is further wet-pulverized in a solvent such as ethanol to loosen aggregates, and is again dried by spray drying to obtain a fine powder. Here, the proportions of each oxide constituting the mixed fine powder are 0.7 to 3 wt zero for chromium oxide, 0 to 0.05 wt4 for magnesium oxide, and the balance for aluminum oxide. In other words, it is not necessary to add magnesium oxide at all.

In addition, to obtain a mixed fine powder of oxides, as shown in Figure 2, polysalts are thermally decomposed to form aluminum oxide, chromium oxide, and magnesium oxide separately, and then these are weighed and mixed. Good too.

Once the mixed fine powder of the oxide is obtained as described above, an organic binder mainly composed of a thermoplastic resin is added to the mixed fine powder, and the mixture is injection molded into a desired shape.

Next, the molded body obtained by injection molding is degreased and then sintered. The sintering conditions are 1280-1300t in the atmosphere, 1280-1300℃ and 10-'-10-' Tor.
N2*A in vacuum at r or at 1300-1350℃
It shall be carried out in an atmosphere of r or N2, and if carried out in the air, the temperature will be increased to 800°C with a heating rate of 200°C/h, for example.
and 1295°C for 1 hour each.

The sintered body obtained as described above is subjected to hot isostatic pressing. The conditions at this time are 1300-1310℃,
The reaction is carried out for 1 hour in an argon atmosphere at a pressure of 1000 to 2000 atm. The product thus obtained is subjected to diamond precision grinding and precision polishing to obtain a final product.

(Effect of the invention) Figure 3 shows the products of the present invention (NO, 1 to B) manufactured by changing the ratio of chromium oxide and magnesium oxide and comparative examples (NO,
7 to 9) are illustrations showing the durability, etc. In addition, a comparative example (
For NO, 9), the starting material was aluminum oxide by the Bayer method, and the temperature was 1575°C
vacuum sintering at 1500°C x 100 [at
Hot isostatic pressing was performed under conditions of m x 1 hr (in AJ).

In addition, for durability testing, we prototyped an ultrasonic type bonding capillary, and after repeating wire bonding 20,000 times, we cleaned it with aqua regia and observed the condition of the tip using an electron microscope (400x magnification), and if there was no change at all. The case where there was some wear was rated A, and the case where 81 falling off or chipping was observed was rated C.

Further, in the workability test, the following precision grinding and polishing were performed by applying a load of 500 g to a sliding precision grinding/polishing machine rotating at 60 rpm.

Grinding Water/Wet 200 Rital Pound Diamond Whetstone 10m1n Polishing Oil/Wet 8μ
Diamond paste/10m1n polishing on ceramic plate
Oil/wet method 1μm Diamond paste/20m1n polishing on copper plate Oil/wet method 0.5μm Diamond paste buffing 10m1n Then, if the mirror surface is obtained after precision grinding/precision polishing, A is the case, and if some scratches remain, B is the case. The case where chipping was significant was rated C.

In addition, regarding the quality of translucency, the obtained sintered body was sliced and polished to a thickness of 0.3 mm, and the tcm
* Judgment was made based on whether the characters on the newspaper were visible.

As is clear from FIG. 3, chromium oxide, 7 to 3.
0*tl, magnesium oxide is O~0.05wt%i
If you can, you can obtain artificial rubies with excellent properties.

To summarize the above, the present invention exhibits the following effects.

First, by using a metal salt as a starting material, sintering can be performed at a low temperature. That is, since the high purity oxide obtained by thermally decomposing a metal salt has an activated surface, sintering can be completed at a low temperature. If the sintering temperature is low, even if magnesium oxide is not added, abnormal grain growth is less likely to occur, resulting in uniform and fine crystal grains. Therefore, although magnesium oxide is not an essential material, its addition improves sinterability.

Furthermore, since a spray drying method is used as a mixing method, various oxides, etc. can be mixed uniformly, and since hot isostatic pressing is performed, the hardness of the product can be increased. In particular, the sintering temperature is 12110℃ or higher, and the hot isostatic press is
0.1 because the temperature was 300℃ or more and 11000at or more
No bores larger than μm remain, and the sintering temperature is 1350℃.
℃ or less, hot isostatic press at 1310℃ or less and 200℃
Since it was set to 0 atm or less, there was no abnormal grain growth of 4 μm or more.

In addition, hot isostatic pressing causes mechanical lattice strain in the crystal, which increases the hardness of the product.

Further, in the present invention, chromium is added, and this chromium easily self-diffuses onto the surface of the material, forming a chromium-rich oxide film on the surface of the ceramic, thereby preventing carbon adhesion and improving hardness and corrosion resistance. However, the proportion of chromium oxide is 0.7wt! If it is less than 6, the desired hardness and corrosion resistance cannot be obtained, and if it is more than 3wtt, a bore of more than 0.1 am will remain in the product after hot isostatic pressing, and the desired toughness and strength cannot be expected. (For chromium salts, convert to chromium oxide) ratio (aluminium oxide,
(100% of the mixture of chromium oxide and magnesium oxide) is preferably 0.7 to 3wt1.

Since the radius of the chromium ion and the radius of the aluminum ion are approximately equal (difference of about 1296), the chromium ion and aluminum ion replace each other during sintering, resulting in lattice strain in the crystal, and this lattice strain causes the above-mentioned Similarly, the hardness of the product is improved.

Therefore, according to the method of the present invention, it is possible to obtain an artificial ruby that has excellent light transmittance, has a uniform crystal grain size, has a dense and fine structure, and has excellent strength, hardness, durability, and workability.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the method of the present invention in the order of steps;
The figure is a diagram showing the process of another example, and FIG. 3 is a chart comparing strength, hardness, etc.

Claims (4)

[Claims] (1) Crystals with an average particle size of 2.0 μm or less in which 0.7 to 3.0 wt% chromium oxide is dissolved in aluminum oxide or 0.7 to 3.0 wt% chromium oxide and 0.05 wt% in aluminum oxide Consists of crystals with an average particle size of 2.0 μm or less in which the following magnesium oxide is dissolved, the internal bore diameter is 0.1 μm or less, there are no coarse particles of 4 μm or more, and the hardness is 2000 HV or more. A polycrystalline artificial ruby characterized by (2) An organic binder is added to a fine powder mixture of oxides containing 0.7 to 3.0 wt% of chromium oxide, 0 to 0.05 wt% of magnesium oxide, and the balance is aluminum oxide, and the mixture is molded into a desired shape. This molded body was heated to 1280 to 1350℃.
1. A method for producing a polycrystalline artificial ruby, characterized in that the sintered body is subjected to hot isostatic pressing at a temperature of 1300 to 1310°C and 1000 to 2000 atm. (3) The mixed fine powder of the oxide is prepared by weighing an aluminum salt, a chromium salt, and a magnesium salt to form an aqueous suspension solution;
This suspended aqueous solution is dried using a spray drying method to form a fine powder.
The method for producing polycrystalline artificial ruby according to claim 2, characterized in that the fine powder is obtained by thermal decomposition. (4) The molded body is sintered in the atmosphere at 10^-^3~10
^-^6 Torr vacuum or N_2, Ar or H
_2. The method for producing a polycrystalline artificial ruby according to claim 2, wherein the method is carried out in the atmosphere described in claim 2.