JPH0349108A - Copper conductor composition material - 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] [Industrial application field] The present invention relates to copper conductor compositions in thick films.

In particular, by using copper powder with a high tap density, the present invention relates to a copper conductor composition having good electrical conductivity, solderability and good adhesion to ceramic substrates.

[Conventional technology]

Generally, a thick film is formed on a ceramic substrate.

As a copper conductor composition for forming a conductive film by baking, inventions such as Japanese Patent Publication No. 43-12858 and Japanese Patent Publication No. 59-2398 are known. Japanese Patent Publication No. 43-12858 discloses a composition comprising fine copper powder, a low-melting glass frit, and a metal oxide, which is applied to the surface of a porcelain substrate.

Further, Japanese Patent Publication No. 59-2398 discloses a thick film conductor composition comprising a mixture of copper, copper oxide, and/or a lead oxide powder and a bismuth oxide powder, a vehicle, and a solvent mixture.

[Problem that the invention seeks to solve]

However, the invention described in Japanese Patent Publication No. 43-12858 uses a low melting point glass frit,
If the sinterability of the copper powder is not taken into account, the composition of copper oxide or glass frit must be quite large, and the thick film formed therefore becomes a frit-bonded conductor, and after sintering, the content of the copper oxide or glass frit must be relatively high. The intermediate layer that develops impairs the heat transfer between the conductor and the substrate, causes cracks during thermal cycles, and at the same time tends to lose adhesion and create areas of low electrical conductivity. It had a

Further, the thick film conductor composition of the invention described in Japanese Patent Publication No. 59-2398 is screen printed on an alumina substrate, dried, and then fired in a nitrogen atmosphere at a temperature of 900 to 1060°C. , the resulting conductor is useful in microwave circuits, exhibiting low resistivity, good solderability and good adhesion to ceramic substrates, but using lead oxide powder and bismuth oxide powder. Therefore, their vapor pressure increases at high temperatures in a non-oxidizing atmosphere, making them more likely to cause oxygen vacancies.
This has the problem of being easily diffused into the atmosphere and requiring caution when used.

The present invention is made of copper powder, copper oxide, glass frit, and an organic substance, and it does not have the problems of using a large amount of glass frit as described above, has good conductivity, and is resistant to soldering and heat cycles. Another object of the present invention is to provide a copper conductor composition having good adhesion to a ceramic substrate.

[Means for solving problems]

The copper conductor composition of the present invention has an average particle size of 1 to 10 μg and a tap density of 4.8 to 5.6 g as a copper powder in a composition containing copper powder, copper oxide powder, glass frit, and organic matter.
The above object has been achieved by including 80 to 90% by weight of the composition in the total composition.

[For production]

In the present invention as described above, since a specific amount of copper powder having a specific lower average particle size and tap density is contained, the conductor composition is highly filled with copper powder, and the sinterability is improved. Since the content of these copper powders is higher than that of conventional compositions with the same components, less glass frit is required in the intermediate layer, resulting in good heat transfer properties, resistance to thermal cycles, and good adhesion and soldering properties. The various properties required for a copper conductor composition, such as properties, are significantly improved.

The present invention will be explained in detail below.

The copper powder used in the present invention has a maximum particle size of 20 μm or less and an average particle size of 1 to 10 μm. When the average particle size is less than 1 μm, the copper powder is
It becomes difficult to contain more than 0% by weight, resulting in poor conductivity and soldering properties, and conversely, if the content exceeds 10 μm, the copper powder in the conductor composition will settle, making screen printing impossible.

A preferred average particle diameter is 1 to 5 μm. Moreover, the tap density of this copper powder is in the range of 4.8 to 5.6 g/cc. The tap density is less than 4.8 g/cc.

Due to poor sinterability, the adhesion strength is poor, and on the other hand, it is 5.6
If it exceeds g/cc, the particle size of the copper powder becomes large, and the copper powder in the conductor composition settles, making screen printing impossible. Such copper powder is contained in an amount of 80 to 90% by weight in the entire composition. If the proportion of copper powder is less than 80% by weight, the conductivity and soldering properties will be poor, and if it exceeds 90% by weight, the proportion of organic matter will be small, making it impossible to obtain a conductor composition suitable for screen printing. becomes.

Copper oxide in the present invention refers to Cub, Cu, and O, preferably Cu and O. These copper oxide powders have an average particle diameter of 1 to 10 μm, more preferably 1 to 5 μm,
It is preferable to contain it in an amount of 0.5 to 2.0% by weight in the total composition.

The glass frit used in the present invention has a softening point of 300 to 7.
00 DEG C. 1, for example, a frit of lead borosilicate glass or lead borate glass, and these glass frits are preferably contained in an amount of 0.5 to 2.0% by weight in the total composition.

In addition, it is preferable that the sum of the weights of oxidized steel and glass frit is 0.5 to 3.0% by weight based on the total inorganic substances,
More preferably, it is 0.5 to 2.0% by weight.

Furthermore, as resins in organic matter, nitrocellulose,
Examples include ethyl cellulose, butyral and acrylic resin. The organic solvent for dissolving these resins is 1
For example, butylcarpitol in polyhydric alcohols,
butyl carbitol acetate (BCA), etc., and terpineol, etc., and a composition using dibutyl phthalate etc. as a plasticizer is preferable, and an organic dispersant may be included.These organic substances are contained in 8-19. It is preferable that the amount of resin is 5 to 30% by weight and the amount of organic solvent is 70 to 95% by weight.The above components are mixed as a conductor composition in a thick film, and used for screen printing, etc. Due to the ceramic substrate on the stem,
200-1 coated with ceramic base material.
After drying in air at 50°C for about 10 minutes,
A copper conductor is formed on a ceramic substrate (usually 96% by weight alumina) f: by firing in a nitrogen atmosphere at ~1000°C.

The following 9 Examples of the present invention are shown below. 9 (Example) A composition having the composition shown in Table 1 was prepared. 5 Then, this was screen printed on a 96% by weight alumina base material, and the mixture was dried in a nitrogen atmosphere. A thick conductor film was formed by holding the peak temperature for 10 minutes and heating and cooling for a total of 1 hour at qoo°C.
Tested for adhesion strength and thermal cycle test. Each test was conducted as follows.

(1) The shape of the copper conductor on the conductive ceramic substrate is length flea, width WC fat, and thickness tcm, and when the resistance value is RΩ, the conductivity of the conductor is specific resistance ρ = Rx (Wxt) / 11Ω・
Represented by cl. The specific resistance in the case of a conductor made of only metallic copper is 1
．． 7μΩ・cm (μΩ・cm= I X 10−'Ω・
The copper conductor on the ceramic substrate has better conductivity as it approaches the resistivity of gold and copper.

(2) For soldering, the copper conductor on the ceramic base material is immersed together with the base material in a small active rosin flux 1 such as Alpha 5002 (manufactured by Alpha Metals), and after drying at room temperature for 1 minute diameter,
Soldering was performed by immersing it in molten solder for 2 to 4 seconds. The solder has a composition of 63% by weight Sn and 37% by weight Pb, and melts in the salinity range of 225-235°C.

Solderability was determined by visually measuring the state of solder coverage on the copper conductor on the base material.

(3) Adhesion strength 2mm x 2mg* diameter OJ on the copper conductor of the pad on the base material
After soldering tin-plated copper wire of 3 mm,
The adhesion strength was measured after 40 cycles of alternating 0 minute and 30 minute stays at 100°C.

These test results are also shown in Table 1.

(Left below) Table 2 shows the properties of the copper powder used in this example.
The composition and properties of the glass frit are shown in Table 3, and the composition of the organic matter is shown in Table 4.

By using copper powder with good sinterability, copper oxide and glass frit that degrade conductivity and solderability are reduced, resulting in a conductor composition that has good conductivity, solderability, and good adhesion. You can get things.

〔Effect of the invention〕

Claims (1)

[Claims] 1. In a copper conductor composition containing copper powder, copper oxide powder, glass frit, and an organic substance, the copper powder has an average particle size of 1
10 μm, a tap density of 4.8 to 5.6 g/cc, and containing 80 to 90% by weight of these copper powders in the entire composition.