JPS63291304A - Metallized constituent - Google Patents

Abstract

PURPOSE:To secure sufficient adhesive strength by constituting a metallized layer, to be installed in a substrate, mounting chip parts for an integrated circuit at high density, with a kneaded material consisting of copper oxide powder, whose wt.% is specified, and CuAl2O4 as well as an organic vehicle. CONSTITUTION:When a metallized layer is formed on a circuit board of alumina or the like, copper oxide powder of 85-99.5 wt.%, an inorganic component consisting of CuAl2O4 of 0.5-15 wt.% and an organic vehicle composed of an organic binder and an organic solvent are used as the metallized layer, and they are kneaded and thereby made into proper viscosity. If so, a manufacturing process of a copper multilayer substrate is promoted into yet lower temperature and shorter time and, what is more, such advantages as lowness of conductor resistance inherent in Cu, goodness of migration resistance, low cost, etc., can be brought into full play.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a metallized composition that can be used as a substrate for high-density mounting of circuits on which ICs, LSIs, chip parts, etc. are mounted and interconnected. It is.

BACKGROUND OF THE INVENTION Conventionally, the metals used for conductor paste of ceramic wiring boards include Au, Au-PL, and Ag-Pt.

Noble metals such as Ag--Pd and base metals with high melting points such as W, Mo, and Mo--Mn have been widely used. The former Au, Au-P
Although noble metal pastes such as T, Ag-Pt, and Ag-Pd can be baked in air, they have the problem of high cost. In addition, the latter high-melting point base metals such as W, Mo, and Mo-Mn are easily multilayered because they are co-fired at a high temperature of about 1,600°C, that is, higher than the sintering temperature of green sheets (about 1,500°C), but on the other hand, they are conductive. is dangerous because it requires firing in a reducing atmosphere.Also,
This method has problems such as the need to plate the conductor surface with Ni or the like for soldering. Therefore, Cu paste, which is inexpensive, has good conductivity, and has good soldering properties, has come to be used. Here, an example of a method for manufacturing a ceramic wiring board using Cu paste will be described.

The conventional method is to screen print Cu paste on a sintered substrate such as alumina to form a wiring pattern, and after drying,
The process involves firing in a nitrogen atmosphere at a temperature lower than the melting point of u and in which the oxygen partial pressure is controlled so that the Cu is not oxidized and the organic components in the conductor paste are sufficiently combusted. In the case of a ceramic multilayer wiring board using Cu paste, the insulation paste and Cu paste are further printed and dried.

Repeat firing in a neutral atmosphere the desired number of times,
This means making it multi-layered.

However, when using the above-mentioned Cu paste, there are several major problems in the method of manufacturing a ceramic wiring board. First of all, in the firing process, Cu
It is extremely difficult to control the oxygen partial pressure in the furnace to such a level that the organic components in the Cu paste are completely combusted without oxidizing the Cu paste. If the oxygen partial pressure is too high, the Cu surface will be oxidized, resulting in poor soldering properties and reduced conductivity.On the other hand, if the oxygen partial pressure is too low, good adhesion of Cu metallization may not be obtained. , difficulties arise in using the organic components contained in the Cu paste. This means that the organic binder used in the paste vehicle is not completely burned off and removed. It is said that the organic binder does not decompose especially at temperatures below the melting point of Cu.

(Reference person, for example, Japanese Patent Application Laid-Open No. 55-128+399) Furthermore, when metal Cu is used, even if the binder removal process and the Cu baking process are separated, the metal Cu will be oxidized in the binder removal process. Since it becomes CuO and causes volumetric expansion, problems such as peeling from the substrate occur. Second,
If you want to make multiple I-, print.

Since firing is performed each time after drying, there are problems in that the lead time becomes long and furthermore, the cost of equipment and the like increases. Therefore, patent application No. 59-14783
In Publication No. 3, a copper oxide paste is used, and the insulating paste and the conductor paste are repeated in the step 11 to form a multilayer structure, and the process is carried out in an oxidizing atmosphere sufficient for carbon and at a temperature sufficient to thermally decompose the organic components inside. A method for manufacturing a ceramic multilayer wiring board has already been disclosed, which is characterized in that heat treatment is performed, and then the atmosphere is made non-oxidizing to Cu, and the printed copper oxide is reduced to metal Cu and sintered. has been done. This method makes it easier to control the atmosphere during firing and allows simultaneous firing. Furthermore, the insulating layer after firing was very dense and had excellent insulating properties. On the other hand, for copper oxide paste,
In JP-A No. 61-183807, Bi2O3°Cd is added to CuO, which has good adhesion to an alumina sintered substrate.
We proposed a copper oxide paste containing O, MnO□, Aff203, etc.

Problems to be Solved by the Invention However, there are problems when producing a copper multilayer ceramic wiring board using the copper oxide paste as described above. This is a method for manufacturing a copper multilayer ceramic wiring board using the above copper oxide paste. The manufacturing process includes a depine removal process, a reduction process, and a firing process, but the temperature of the firing process is particularly high at 1000°C, and the temperature rise/decrease rate is 300°C.
/There is a problem in that the lead time becomes long because the time is slow. This is because borosilicate glass-alumina is used as the insulating layer material. Therefore, in order to realize a lower temperature and shorter time for manufacturing copper multilayer ceramic wiring boards, an insulating paste composition mainly composed of glass containing lead oxide was proposed in Japanese Patent Application No. 1999-61-74739. .

However, for the above insulation paste composition, as a copper oxide paste, CuO contains B! 203°CdO,
When using a material to which MnO2, Afi, 08, etc. were added, there was a problem in metallization, and good adhesion was not obtained between the insulating layer and the conductor layer.

Furthermore, even on 96% A#208, sufficient adhesive strength could not be obtained when the firing time was shortened.

Means for Solving the Problems In order to solve the above problems, in the metallizing composition of the present invention, at least an organic binder and an organic solvent are added to the inorganic component, which is copper oxide powder with Cu Al 204 added as an additive. It is prepared by adding an organic vehicle containing the ingredients and kneading it to an appropriate viscosity.

Function As described above, since the present invention is a copper oxide paste, heat treatment can be performed in advance in an oxidizing atmosphere sufficient to remove the organic binder. is hardly affected by residual carbon.

Further, since the binder is removed in an oxidizing atmosphere, the organic vehicle material for the paste can be selected from a wide range. Zero-order CuAl204 is effective in improving the adhesive strength of the Cu metallized layer. Cu layer and 96Af
At the interface between the 203 substrate and the insulating layer, CuAl20.
layer is formed, and the products at this interface play a major role in obtaining adhesive strength. The CuAl20. By pre-adding CuO as an inorganic component to the metallization composition (copper oxide paste), a small amount of addition can have a sufficient effect on adhesion. It was found to be very effective in time management.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

First, the ceramic substrate material according to the present invention has 1 inch x 2
A sintered substrate made of 96% alumina and having a thickness of l ist was used. As the metallizing composition, Cu
As shown in Table 1, an inorganic component powder containing O powder as the main component and Cu A 120 a as an additive was added with a vehicle containing ethyl cellulose as an organic binder in terpineol. A CuO paste was used by kneading it with corrugated rolls to a suitable viscosity. Ceramic wiring boards were prepared using the paste thus prepared, and adhesive strength and solderability were evaluated. The test piece for evaluation has a cross section as shown in FIG. ta+ is the case where the conductor layer is formed on the alumina substrate, and (bl is the case where the conductor layer is formed on the insulating layer).

(Margins below) Table 1 Here CuAl20. This is the preparation of an equimolar mixture of CuO and Al2O3 at 800°C to 90°C in an oxygen atmosphere.
It was heat treated at 00°C for 3 hours and ground in an agate mortar.

Next, the insulation paste used in this example is an inorganic powder made by mixing glass powder and ceramic powder in a 1:1 weight ratio with the composition shown in Table 2, and ethyl cellulose as an organic binder. A mixture of terpineol and a dissolved vehicle was used, which was kneaded using three-stage rolls to obtain an appropriate viscosity.

(Left below) Next, we will explain how to make the test pieces fat and (bl.) First, the test piece (al) is made of
A conductor pattern was formed by printing a copper oxide paste using a 250 mesh emulsion screen with a thickness of 5 μm and drying (at 120° C. for 10 minutes). Test piece (for BL, apply insulation paste on an alumina substrate with a 200 mesh emulsion thickness of 10
Using a μm screen, print on the entire surface and dry (1
After that (at 20° C. for 10 minutes), copper oxide paste was printed on the insulating layer under the same conditions as in the case of fat, and dried to form a conductor pattern.

Next, the binder was removed using unsintered test pieces consisting of these two types of configurations, FAT and FBL. The point is 650°C.

Therefore, it is necessary to remove the binder at a temperature below the softening point. Further, since the organic binder used in the copper oxide paste and the conductive paste is ethyl cellulose, a temperature of about 600° C. or higher is desired in order to decompose it in a short time (about 100 minutes) by heat treatment in the air. Therefore, the binder was removed at 600°C. This is because if the binder is removed at a temperature higher than the softening point, the cupric oxide inside is sealed as it is, so there is a risk that it will not be able to be reduced to copper in the subsequent reduction step. In addition, the decomposition and removal of ethylcellulose was investigated by analyzing carbon that remained undecomposed by heat treatment in the air. Result 5
At 00°C, the amount of carbon was approximately 150 ppm, at 550°C, it was 80 ppm, and at 600°C, it was a few top ppm, indicating that sufficient decomposition and removal was possible.Figure 2 shows a schematic diagram of 0-pine mites. Ta.

Next, the profile of the reduction process is shown in FIG.

First, the debinding unsintered body was inserted into a 120 mm diameter tube furnace, and nitrogen gas was flowed into the furnace core tube at a flow rate of 0.76/min and hydrogen gas was flowed into the furnace core tube at a flow rate of 0.117 min. Reduction is 4
It was held at 00°C for 2 hours, and after cooling, it was taken out. It is said that the reduction of CuO to metal Cu occurs at about 250°C in H2 gas, but when reduced at a temperature of about 300°C,
There is a black part believed to be CuO inside the conductor layer. On the other hand, when reduced at a temperature of about 600°C or higher,
The insulation layer turns gray. This is due to reduction of lead oxide in the insulating layer. Therefore, the reduction temperature in this example was set to 400°C.

Next is the firing process. The furnace used was a Mesoshevert furnace (200 ts belt width) manufactured by BTU Engineering, and the atmosphere was pure nitrogen. At this time, the amount of residual O2 inside is reduced to 0.
□ Measured with a densitometer, it was 1-21)I)m. The temperature profile of the firing process is shown in FIG.

Using the test piece prepared as described above, the adhesive strength and solderability of the conductor layer were evaluated.

Regarding soldering properties, the wettability was qualitatively judged by dipping the product in a solder dip bath, and rated as excellent or good, which is within the practical range. On the other hand, the adhesive strength is 211
A lead wire with a diameter of 0.8 mm was soldered perpendicularly to the board in a square pattern, and its breaking strength was measured using a tensile tester. The solder is 62% Sn, 36% Pb, 2
%Ag was used.

The results measured as described above are summarized in Table 3. As is clear from the table, with 100% CuO, almost no adhesive strength can be obtained on either the alumina substrate or the insulating layer, but with 100% CuO. The adhesive strength increases rapidly just by adding 5 wt% of Q. The adhesive strength reached its maximum value when the amount of CuAl204 added was 5 wt%, and although it gradually weakened thereafter until the amount added was about 20 wt%, it had sufficient adhesive strength. Regarding soldering, this is also Cu A jl 2
It is very good when the addition amount of 0□ is up to 5wt%, and l 5wt
% was within the practical range.

However, with addition of 2Qwt%, there is concern about soldering performance.

From the above results, the allowable range for the amount of CuAl2O added is 0.5 to 5wt%, and the optimal amount is approximately 5wt%.
It is wt%.

(Margins below) Table 3 Next, in order to show that the metallizing composition of the present invention is very excellent as a conductive layer for a copper strip layer board fired at low temperature and in a short time, 20° of AJ was added to CuO. The above measurements were performed using a copper oxide paste prepared by The results are shown in Table 4.

Table 4 As is clear from this table, An208 is not very effective as an additive under the firing conditions of low temperature and short time, and CuAl204 is very effective as an additive.

Effects of the Invention As described above, the metallizing composition of the present invention can be said to be very effective as a conductor layer material when the manufacturing process of a copper strip layer board is lowered in temperature and shortened in time. In addition, the copper strip layer ceramic substrate produced using the metallized composition of the present invention fully takes advantage of Cu's low conductor resistance, good solderability, good migration resistance, and low cost. This is an industrially extremely effective invention.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a test piece produced using the metallizing composition of the present invention, FIG. 2 is a characteristic diagram showing the temperature profile of depine mites in the production method of the present invention, and FIG.
The figure is a characteristic diagram showing the temperature profile of the reduction process.
The figure is also a characteristic diagram showing the temperature profile of the firing process. 1... Copper metallized layer, 2... Insulating layer containing lead glass, 3... Alumina sintered substrate. Name of agent Patent attorney Toshio Nakao 1 name Figure 1 1-11 Including 夙STARRAIG, @ (()-) s... 4 diagram maki Seki (Bri)

Claims (1)

[Claims] Copper oxide powder 85-99.5% by weight and CuAl_2O_4
A metallizing composition comprising an inorganic component of 0.5 to 15% by weight and an organic component containing at least an organic binder and an organic solvent.