JPH03218993A - Metallizing method for ceramics - Google Patents

Abstract

PURPOSE:To stably form a metallized layer having excellent joint strength, etc., and high reliability by specifically regulating the grain size of high melting metal powder and the grain size of ceramics at the time of forming the metallized layer on the surface of the ceramics by using the high melting metal powder. CONSTITUTION:The high melting metal powder having such an average grain size as to satisfy the relation (R=Dm/Dc) when the average grain size of the high melting metal powder is designated as Dmmum and the average grain size of the ceramics as Dcmum is prepd. at the time of forming the metallized layer on the surface of the ceramics by using the high melting metal powder (e.g.; molybdenum powder). This high melting metal powder and glass powder are then mixed and the powder mixture is kneaded by an org. solvent to produce paste. This paste is applied on the surface of the ceramics (e.g.; alumina) and is calcined, by which the metallized layer is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION r Industrial Application Field The present invention relates to a method for metallizing ceramics, and more particularly to a method for metallizing high melting point metals.

[Conventional technology]

As a pre-treatment for joining metal and ceramics,
It is well known to perform metallization treatment on the surface of ceramics. This metallization method includes high melting point metal method,
Various methods are known, such as an active metal method and an oxide solder method. Among them, electron tubes such as magnetron insulated tubes for microwave ovens and vacuum switch envelopes require vacuum sealing properties, so the high melting point metal method, which is the most reliable of the metallization techniques mentioned above, is generally used. It is used.

A typical method for metallization using a high melting point metal method is, for example, the method described in JP-A-59-156981. This high melting point metal method involves applying a mixed powder paste of high melting point metals such as Mo or W and Mn to the ceramic surface, and firing it in a humidified hydrogen atmosphere to form a high melting point metal layer on the ceramic surface. It is.

The paste is generally made by mixing the metal powder with about 10 to 30% of an organic solvent. After metallization, various treatments are performed to remove oxides from the surface and remove glass components that have penetrated the surface. After that, Ni plating is performed. Furthermore, a sintering process is performed after Ni plating. However, in the high melting point metal method, in addition to setting each condition of the above steps,
A sound metallized layer cannot be formed unless various conditions such as the composition of the ceramic sox, particle size, and shape of the metal are optimal.

For this reason, in the past, in order to find the above-mentioned conditions, it was necessary to conduct preliminary experiments under various conditions. For example, a huge amount of experimentation is required, such as by changing the firing time while keeping the firing temperature constant, or by changing the thickness of the coated metal layer for metallization. Therefore, it has been desired to develop a method that eliminates these uncertain factors as much as possible and presents a quantitative method for quickly determining metallization conditions.

[Problem to be solved by the invention]

The purpose of the present invention is to provide a highly reliable metallization method that eliminates various uncertain factors in the bonding of metals and ceramic materials as described above. This is a technology that quantitatively presents the conditions.

[Means to solve the problem]

The present invention, which solves the above-mentioned problems, presents optimal conditions for the relationship between the particle sizes of ceramics and metal powder among the above-mentioned uncertain factors in the high-melting point metal metallization method. In a high melting point metal metallization method in which a paste made by kneading a mixed powder of high melting point metal powder and glass powder with an organic solvent is applied to the surface of A method for metallizing ceramics is characterized in that the diameter satisfies the relationship of formula (1) below.

R×(1~R)>0.1 (1) However, R=Dm/Dc Dm: Average particle size of high melting point metal powder (Rhin) DC: Average particle size of ceramics (Rhin) C action] The high melting point metal method was invented 40 years ago, and its properties are very good. The high melting point metal method is a method in which, as described above, a high melting point metal such as 10 or W is used, the metal is used as a skeleton of a metallized layer, and the space between them is filled with a glass layer. The Mo-Mn method, which is a typical example of the refractory metal method, will be described. First, metal powders of Mo and Mn are mixed with organic oil to form a paste, which is applied to the top surface of the ceramic and dried.

Next, the coated material is held in a furnace controlled to have an atmosphere in which Mn is oxidized but Mo is not oxidized. Typical atmospheric conditions are N2:H2=9:1, dew point 40°C,
The atmosphere has a temperature of about 1450°C.

Mo sinteres at this temperature, forming a metal network and forming the skeleton of the metallized layer. On the other hand, Mn oxidizes to become MnO, and A72 in the base material ceramics.
0:l. Reacts with CaO, MgO, etc. to form a fluid oxide with a low melting point. This oxide fills the gaps in the funotowork of gate 0 and improves the vacuum sealing properties. The subtle difference between the sintering of gate 0 and the flow of glass is the
- This is an important item in the Mn method. More than,! 'to -
This is the inventor's findings regarding the mechanism of the Mll method.

There are also methods of using oxide solder instead of Mn and using W instead of Mo, but the basic mechanism is the same. Also, recently, by applying this method, Af
Methods of metallizing fiN, slC, and other ceramic materials have been reported, but the mechanism is similar: a metal with a relatively high melting point is used as a skeleton, and the gaps are filled with oxide solder.

In the refractory metal metallization method described above, it is essential that the glass layer is filled with a refractory metal skeleton. Therefore, the present inventors believe that this degree of filling is the most important factor in the uncertainty of metallization strength, and note that the second degree of filling is determined by the relationship between the particle size of the ceramic and the metal. However, by repeating experiments under various conditions, they arrived at the present invention.

Next, a specific method of the present invention will be explained based on the drawings.

First, as shown in FIG. 6, a base F for notarising is applied to the surface of the seven-laminated sox ring 2, and is fired under the conditions described later to form a metallized layer L. Ceramics are
It was configured in a ring shape to facilitate evaluation of tensile strength and vacuum sealability, which will be described later.

The metallizing paste is prepared as follows.

Metal powders such as Mo and W and glass powders were mixed at 80220 (w
t%), then add 10 to 20% of oil (organic solvent) for paste preparation, and mix with a ball mill at a ratio of 12 to 7%.
Knead for 2 hours. As an example of the oil for preparing the paste, a mixture of an organic binder such as ethyl cellulose and an organic solvent such as terpineol and the like was used to obtain an appropriate viscosity.

Metal powders such as Mo and W, and glass powders have an average particle size of 0. For the ceramic ring, the firing time and firing temperature during ceramic production were controlled so that the average particle size of the ceramic was 1 to 10. The glass powder used was A1z01 MnOS10. The melting point ranges from 1200°C to 1400°C.

The paste produced by the above method was applied to the upper surface of the ceramic ring 2 and dried. This coated ceramic ring 2 is fired to form a metallized layer 1.
The firing conditions were as follows: gas composition of N2:H2=90:10, temperature range of 1300 to 1500°C, and firing time.
It takes 1 to 2 hours.

Since it is difficult to braze the metallized layer 1 formed as described above, N1 plating is applied to its upper surface. This Ni plating is performed after various preliminary treatments such as hydrochloric acid treatment and palladium chloride treatment. After Ni plating, the Ni plating metal is sintered at around 900°C. This forms a brazeable metallized layer 1.

Next, in order to evaluate the strength of the metallized layer 1, a second
As shown in the figure, Ag is attached to the upper and lower ends of the ceramic ring 2.
- A sample was prepared in which the iron plate 3 was brazed using Cu-based Ginkgo. Brazing was carried out using BAε8 (commercially available) and maintained at 800 to 850°C for 10 minutes.

The second sample was subjected to a tensile test as shown in the second section, and was judged to have passed if the tensile strength was 250 kgf or more, which is required in normal use. In addition, in FIG. 2, 4 is a tensioning jig.

On the other hand, in order to evaluate the vacuum sealability, as shown in FIG. 3, one end of the ceramic ring 2 was sealed by brazing the above-mentioned iron plate 3, and a copper pipe 5 was connected to the other end. Although not shown, a rubber tube was connected to this and connected to a He leak detector. The vacuum sealing performance is evaluated by detecting the amount of leakage using this He leak detector.
A He leakage amount of 10-10 torrf/sec or less was considered to be a pass.

Tables 1 to 3 show examples of the results of carrying out the above evaluation tests while changing the average particle diameters of ceramics and metal powder.

As is clear from the above results, the characteristics of metallization are
It was found that the particle size of ceramics and metal particle size depend more heavily, and from this acceptance range, it was found that the effective relationship between the particle size of ceramics and metal should satisfy the following relationship. .

That is, Rx (1 - R) > o. 1...1~...
-- (1) However, R-Dm/Dc Dm: Average particle size of high melting point metal (μm) Dc: Average particle size of ceramics (n) [Example] Example 1 First, a paste was prepared as follows. did. Average particle size 2I
! Irl Mo and glass powder with an average particle size of 1, 80:
Mixing L was added at a ratio of 20 (wt%), and then 12% of oil for making haste was added. Glass 1M [, A/20z
MnOSiOz=30:3G:4
It was 0. This mixture is kneaded in a ball mill for 24 hours. The oil for preparing the paste used was ethyl cellulose dissolved in terpineol.

Next, apply this paste to the ceramic ring 2 shown in Figure 1.
It was applied by screen printing method and dried. The ceramic ring 2 has a composition of 92% N203. The average grain size of the alumina was 4 mm. Therefore, R×(1−R) in the above formula (1) in this example is 0.25,
0. 2 5 > 0. 1, satisfying the condition of equation (1).

Next, the ceramic ring 2 coated with the paste was fired. This condition is Nz:H2-90:1
Gas composition: 0, firing temperature: 1450°C, firing time: 1
It was time. Next, various preliminary treatments such as hydrochloric acid treatment and palladium chloride treatment were performed, and then N1 agate wood was applied. N
I-mentioning was performed by electrolytic plating. After Ni Menki, 9
of Ni agate metal at 00°C. / I conducted an interview.

After completion of notarization, a brazing material was placed on the surface, a steel plate for tensile testing was placed on top of it, and brazing was performed.

For filtering and dipping, use BAg-13 (commercial product) 850
"C% was maintained at 10 min.

The tensile test was performed at a tensile speed of 1. 0mm/win
．． The strength at which rupture occurred was defined as the bonding strength.

Further, to evaluate the vacuum sealability, as shown in FIG. 3 described above, a copper pipe was joined and tested using a helium leak detector.

It should be noted that 10 pieces of each test were conducted.

The results are shown in Table 4.

Table 4 Example 2. Mo of 1 mushroom with average particle size and glass powder with average particle size of μm,
They were mixed at a ratio of 82:1B (wt%), and then 12% of paste-making oil was added. The glass composition is jVz(
hMnOSiOt=30:30:40
Met. This mixture is kneaded in a ball mill for 24 hours. Is ethyl cellulose replaced with terpineol for paste making oil? I used what I understood.

Next, this paste was applied to a BeO sintered plate shown in FIG. 4 by screen printing and dried. The average particle size of BeO was 3p. In this case, in the above formula (1), RX
(1-R) is approximately 0.22, which exceeds 0.1.

Next, the paste-coated BeO sintered plate was fired.

The conditions were a gas composition of N2:H2=90:10, a firing temperature of 1400°C, and a firing time of 1 hour.

Next, various preliminary treatments such as hydrochloric acid treatment and palladium chloride treatment were performed, and then Ni agate treatment was performed. N] Plating was performed by electrolytic plating. After Ni agate, 900°C"'
Nontalling of eNi agate metal was performed.

After the metal lining was completed, a brazing material was placed on the surface, six iron plates for tensile testing were placed on top of it, and a rolling test was performed.

For brazing, use BAg-8 (commercially available) at 850°C.
, 10 shin. I held it in place.

The tensile test was performed at a tensile speed of 1.0w/IIIin. The strength at which rupture occurred was defined as the bonding strength.

Further, the vacuum sealability was evaluated using a helium leak detector in the same manner as in Example 1. The number of test samples was 10 each.

The results are shown in Table 5.

Table 5 Example 3 W with an average particle size of 1.5p and glass powder with an average particle size of 1μ,
They were mixed at a ratio of 90:10 (wt%), and then 12% of paste-making oil was added. The glass composition is IVzO
3MnOSiOz=30:30:4
It was 0. This mixture was kneaded in a ball mill for 24 hours. The oil for preparing the paste used was ethyl cellulose dissolved in butyl carbitol.

Next, this paste was applied to an AZN sintered plate (the form is the same as the BeO sintered plate shown in FIG. 4 above) using a screen printing method,
Dry. The average particle size of A7N was 2 mm. In this case, RX (1-R) in the above formula (1) is about 0.19, which is more than 0.1.

Next, the coated 71jN sintered body was fired. The conditions were a gas composition of Nz:Hz 90:10, a firing temperature of 1500°C, and a firing time of 1 hour.

The subsequent steps were the same as in Example 2, including a tensile test and
Vacuum sealability was evaluated.

Note that the number of test samples is 10 each.

The results are shown in Table 6. [Effects of the Invention] As explained above, according to the present invention, if the particle size of the metal powder and the particle size of the ceramic are set as in equation (1) above, It has become possible to obtain the maximum metallization characteristics. This has resulted in a significant reduction in the time and cost conventionally spent searching for such conditions.

[Brief explanation of drawings]

Each figure shows an embodiment based on the present invention, and FIG.
A perspective view of an example of a metallized layer formed on a ceramic ring, FIG. 2, and FIG. 3 show an example of an evaluation test for a metallized layer formed based on the present invention. Test: Figure 3 is a diagram of the vacuum sealability test. FIG. 4 is a perspective view showing an example of a metallized layer formed on a BeO sintered plate. 1: Metallized layer, 2: Ceramic sox ring, 3: Iron plate, 4: Tensile jig, 5: Copper pipe, 6: BeO sintered plate.

Claims (1)

[Claims] A high melting point metal metallization method in which a paste prepared by kneading a mixed powder of a high melting point metal powder and a glass powder with an organic solvent is applied to the surface of a ceramic, and the paste is fired. A method for metallizing ceramics, characterized in that the average particle size of metal powder in the paste satisfies the following relationship (1). R×(1-R)>0.1...(1) However, R=Dm/Dc Dm: Average particle size of high melting point metal powder (μm) Dc: Average particle size of ceramics (μm)