JPH01319203A - Titanium boride paste and pattern forming method using same - Google Patents

Abstract

PURPOSE:To obtain a low resistance circuit wiring material by adding metal aluminum and calcium oxide to titanium boride paste whose main component is impalpable powder of titanium boride. CONSTITUTION:An organic solvent is added to titanium boride, metal aluminum, calcium oxide powder and pasted. This titanium paste is printed on a green sheet of aluminum nitride and a pattern is formed, and thereafter baked integrally to produce internal wiring material. Then oxygen contained in the titanium boride is reacted with the metal aluminum melted at a high temperature to form alumina, and the formed alumina is reacted with the calcium oxide at a higher temperature to produe a liquid phase of calcium aluminate and this liquid phase having a high vapor pressure is evaporated away by further temperature raising process to remove the oxygen. Thus, the impurity, is removed from the titanium boride powder and a circuit wiring with a very electric resistance can be formed.

Description

[Detailed Description of the Invention] [Summary] Regarding a titanium boride paste and a pattern forming method using the same, oxygen contained in titanium boride powder is removed to form circuit wiring materials with low electrical resistance, especially nitrided The purpose is to provide an internal wiring material for aluminum circuit boards, and consists of a paste containing titanium boride as the main component, to which metal aluminum and calcium oxide are added, and a pattern forming method using this paste.

[Industrial application field]

The present invention relates to a titanium boride paste and a method for forming a titanium boride pattern using the same.

[Conventional technology]

Aluminum nitride has high thermal conductivity and thermal expansion close to that of silicon, so it is seen as a promising material for LSI packages, multilayer circuit boards, and the like. Titanium boride is attracting attention as a material for this wiring. Titanium boride has lower electrical resistance and higher melting point than W etc.
This is because it is suitable as an internal wiring material for aluminum nitride circuit boards that must be fired at high temperatures.

[Problem to be solved by the invention]

Titanium boride has a high melting point, so fine powder must be used to improve its sinterability, but titanium boride is extremely hard and difficult to grind into fine powder, so the amount of oxygen is low. There was a problem in that the electrical resistance increased and the electrical resistance became larger than the originally expected value.

Therefore, an object of the present invention is to remove oxygen contained in titanium boride powder and provide a circuit wiring material with low resistance in order to reduce the resistance of wiring using titanium boride.

[Means and effects for solving the problem] In the present invention, metallic aluminum and calcium oxide are added to a titanium boride paste whose main component is fine powder of titanium boride, which inevitably contains oxygen. Problem solved.

In other words, the oxygen contained in titanium boride is heated to high temperature (660°C).
above) to generate alumina, and at a higher temperature (1400°C or higher), the generated alumina and calcium oxide are reacted to generate a liquid phase of calcium aluminate (Can・2A1203). This liquid phase, which has a high vapor pressure, is evaporated and scattered during a further heating process to remove oxygen.

The amount of metal aluminum may be in a molar ratio of 2:3 or more to oxygen, which is necessary to form alumina. The amount of calcium oxide may be at least the amount necessary to form calcium aluminate (molar ratio of 1=4 or more with respect to metal aluminum). These amounts depend on the titanium boride powder used, but generally titanium boride 100
Metal aluminum is 0.5 to 12 parts by weight, preferably 1 to 10 parts by weight, and calcium oxide is 0.5 parts by weight.
~6 parts by weight, preferably 1 to 5 parts by weight. The oxygen content of titanium boride powder is usually about 0.5 to 3% by weight.

To make a paste of titanium boride, aluminum metal, and calcium oxide, it is sufficient to knead them with components commonly used for making pastes, such as an organic binder, an organic solvent, and a plasticizer. The mixing ratio of solid powder such as titanium boride and organic binder may be determined by a conventional method, but generally the solid content is 70 to 9 Qwt%, preferably 75 to 35 wt%.

This titanium boride paste is particularly suitable as an internal wiring material, especially for aluminum nitride circuit boards. That is, after printing this titanium boride paste on an aluminum nitride green sheet to form a pattern, the green sheets are laminated and integrally fired to produce an aluminum nitride multilayer circuit board using titanium boride as an internal wiring material. .

In this way, a titanium boride wiring material that can withstand the firing temperature of aluminum nitride and becomes dense at that temperature is obtained.

This titanium boride paste, however, can also be used in combination with substrate materials other than aluminum nitride,
It may also be used to form patterns on hard ceramic substrates.

The firing conditions for this titanium boride paste may basically be the same as those for conventional titanium boride pastes, but the following conditions are typically employed.

Temperature: 1800-2000°C Atmosphere: N2 or Ar Time: 3-24h Pressure Normal pressure According to the present invention, since oxygen contained in titanium boride can be effectively removed, the electrical resistance of circuit wiring can be reduced, and the theoretical value can be approached.

〔Example〕

8 g of metal aluminum powder with 4 particle sizes is added to 200 g of titanium boride powder with an average particle size of 1.0 mm and an oxygen content of 2 wt%.
Furthermore, 4 g of calcium oxide powder with a particle size of 3 mm was added. Next, an organic binder and an organic solvent were added and mixed using a ball mill, and further kneaded using a sieve machine and a three-roll mill to prepare a paste.

This paste was screen printed on an aluminum nitride green sheet with a thickness of 300β and a width of 150-1 and a thickness of 30
A trend pattern was formed. This green sheet was placed in an intermediate layer to produce a 10-layer laminate, which was degreased in a nitrogen atmosphere at 600°C. Next, it was fired for 5 hours in nitrogen at 1800°C.

After firing, the electrical resistance of the internal wiring was measured. In addition, the amount of oxygen was analyzed using a sample obtained by firing this paste alone. These results are shown in Table 1.

For comparison, a paste was prepared in the same manner as in the example, using only the same titanium boride powder as in the above example, without adding metal aluminum and calcium oxide, and adding an organic binder and an organic solvent. A sample was prepared from this paste through the steps from screen printing to firing in the same manner as in the example. The electrical resistance of the firing machine was measured. Further, only the paste was fired in the same manner, and the amount of oxygen was measured. The results are also shown in Table 1.

Table 1 [Effects of the Invention] As explained above, according to the present invention, impurity oxygen can be removed from titanium boride powder, and circuit wiring with extremely low electrical resistance can be formed.

Claims (2)

[Claims] 1. A titanium boride paste whose main ingredient is titanium boride, to which metal aluminum and calcium oxide are added. 2. A method for forming a titanium boride pattern on an aluminum nitride substrate, comprising the steps of applying the titanium boride paste according to claim 1 on an aluminum nitride green sheet, and firing the aluminum nitride green sheet. .