JPS63207001A - Conducting composition - 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 the Invention The present invention relates to an electrically conductive composition for baking thick film conductors onto an extremely curved substrate.

Conventionally, a conductive composition is applied onto an insulating substrate such as ceramics or glass by a method such as screen printing.
It is widely practiced to manufacture wiring conductors for electronic circuits, electrodes for capacitors, resistors, etc. by firing at high temperatures. This conductive composition mainly consists of Ag, Au, Pd,
It is made by dispersing conductive powder such as Pt, Cu, Ni, etc. and an inorganic binder such as glass or metal oxide in an organic vehicle.It is generally highly conductive, has strong adhesive strength with the substrate, and has high heat resistance. It is required to have characteristics such as low deterioration due to drying, resistance to repeated firing, good solder wettability, and low solubility in solder.

Adhesion between the thick film conductor and the substrate is achieved using an inorganic binder, but adhesion and solder wettability are usually contradictory properties, and if a large amount of binder is added to increase the strength, the binder will cause the sintered product to A large amount remains on the surface and inhibits solder wettability.

Various glasses and additives have been tried in the past in order to improve adhesion without impairing solder wettability, and in particular to reduce the decrease in adhesive strength due to thermal aging. For example, Japanese Patent Publication No. 61-51361 discloses that Bi is added to the conductive composition.
It has been shown that the addition of 2es and ZnO improves solder wettability and adhesive strength.
Publication No. 2805 describes the use of glass with a special composition of lead-zinc borosilicate for AQ-based conductors. Furthermore, Japanese Patent Application Laid-open No. 58-87164 filed by the present applicant discloses that thermal deterioration can be improved by adding a zinc oxide-cobalt oxide solid solution.

However, in recent years, there has been a strong demand for circuit miniaturization and cost reduction, and there is a demand for smaller and smaller areas of electrodes and conductor patterns, as well as thinner conductor films. For this reason, there is a desire for a material with stronger adhesive strength and better solder wettability, and even with the conventional conductive compositions described above, it is still difficult to find one that satisfies both strength and solder wettability. It has not been done.

In addition, the adhesive strength of thick film conductors generally depends on the fired film thickness.
If the film thickness is too thin, sufficient strength cannot be achieved. For example, Ag/Pd, which is currently widely used as a circuit conductor.
Type and A(J/Pt type conductors are usually designed to have a film thickness of 12 to 20 μs, and if the adhesive strength is less than 10 μs, the adhesive strength is extremely weak, which poses a practical problem.

Furthermore, in order to shorten the firing time and lower the process cost, high-speed firing using an infrared furnace has recently been carried out, but when the conventionally used 11-electroconductivity composition is fired at high speed, the conductor surface may be damaged, especially when the film is thick. Phenomena such as glass floating, glass seeping out from the pattern, and foaming occurred, leading to a decrease in solder wettability and adhesive strength, making it impossible to form a good conductor.

The present invention aims to meet the above-mentioned demands (to provide a conductive composition that has excellent solder wettability, further improves adhesive strength with a substrate, especially adhesive strength after heat aging, and can be made into a thin film. With the goal.

Another object of the present invention is to provide a conductive composition that can be fired even in an infrared high-speed firing furnace.

Steps for solving Question 1 The present invention provides a conductive composition comprising a conductive metal powder and an inorganic binder dispersed in an organic vehicle, in which the inorganic binder is (a) the sum of 8203, ZnO and PbO. 100
MOO30.5-5.01ffi% based on weight%, M
nO20.5-3.0% by weight, TiO20.5-3.0
(b) 1.0 to 5.0 parts by weight of bismuth oxide, (c) 0.10 to 1.00 parts by weight of manganese oxide, and (d) oxidation. The second invention is characterized in that it consists of 0.10 to 1.00 parts by weight of one or more selected from zinc-cobalt oxide solid solutions, and the second invention is characterized by comprising the above (a) to (d). The ingredients further include (e) 0.02 to 0.30 parts by weight of one type or 21a or more oxide selected from R-chromium oxide and titanium oxide, and (f) 0.10 to 1.00 parts by weight of lead oxide. This is a conductive composition characterized by using an inorganic binder added with.

1 Dish The present invention uses a solid bonding agent that combines glass with a specific new composition and specific additives to improve adhesive strength and
This significantly improves aging strength and solder wettability. Moreover, the second invention further enables high-speed infrared firing.

When designing a conductive composition, the present inventors considered the following film structure to be an ideal form for a thick film conductor.

(1) There is very little vitreous material as a binder near the surface of the fired film, and it is distributed as much as possible on the substrate side.

(2) In the area between the gold B layer of the conductor film and the glass layer near the substrate, a metal-glass matrix structure is formed in which glass is densely embedded between the sintered metal powders, and the glass layer and The contact area of the gold a layer is large, and the two are firmly adhered.

(3) Furthermore, the formed metal-glass matrix structure is difficult to change due to heat.

A conductor film structure that meets these conditions will have good solder wettability because there is almost no glass on the film surface, and the film will have a very strong adhesion strength to the substrate and the film will become a conductor, and will resist heat after firing. It is expected that the strength will not deteriorate easily even after being exposed to history. Therefore, as a result of repeated studies to create such a membrane II4 structure, a novel glass composition of the present invention was discovered.

The glass (a) used in the present invention has a large viscous flow near the softening point, so the glass quickly moves toward the substrate during firing, but at the same time, the difference between the softening point and the crystallization temperature is small, and the glass softens quickly. Since crystallization occurs, the glass does not move entirely, but a portion is fixed in the film, making it easy to form the metal-glass matrix described above.

The main components of the glass are Pb 2 O, 8203 and ZnO, and because it does not contain Si 0 2 , it has high fluidity near its softening point. The preferred composition range is that the total of these three components is 101
When 1ffi%, 820322~35fi1%, Z
n 020-50% by weight, Pb 013-57m! 1%
It is. If B2O3 is less than 22% by weight, it becomes vitrified, but if it exceeds 35% by weight, it does not crystallize. When zno is less than 20% by weight, it is difficult to crystallize, and when it exceeds 50% by weight, it is not vitrified. If PbO is less than 13% by weight, the softening point is too high, and if it exceeds 57% by weight, it is too low. MOO3 as an additive component has the effect of sufficiently wetting the metal by increasing the fluidity of the glass and quickly moving the glass to the substrate side, and has a content of 0.5 to 5.0% relative to 100% by weight of the main component.
% by weight is added. If it is less than 0.5% by weight, solder wetting is poor, and if it exceeds 5.0% by weight, it is difficult to vitrify.

Both MnO2 and Ti02 are blended for the purpose of suppressing excessive viscous flow, and have the effect of increasing strength, preventing glass from floating during infrared firing, and further preventing softening and flow of glass during repeated firing. In either case, if the amount is less than 0.5% by weight based on 100% by weight of the main component of the glass, there is no effect, and if it exceeds 3.0% by weight, vitrification becomes difficult.

By using this glass, the above-mentioned desirable 11
It is possible to make a 9M4 structure and form a conductive film with excellent characteristics. However, with glass alone, there were still some dissatisfaction with performance such as adhesive strength and solderability.

In the present invention, manganese oxide and zinc oxide-cobalt oxide solid solution as inorganic additives added to glass serve to supplement and enhance the effects of glass. Manganese oxide strengthens the metal-glass matrix 411 to create a dense structure, and has the effect of improving strength and preventing the glass from softening and flowing during repeated firing. .10 to 1.00 parts by weight is blended. If it is less than 0.10 parts by weight, the adhesive strength will not be sufficient, and if it exceeds 1.00 parts by weight, it will not be possible to form a dense film and the strength and solder melting resistance will deteriorate. The zinc oxide-cobalt oxide solid solution reacts with the substrate to improve the adhesive strength between the substrate and the glass in the conductor film, and is disclosed in Japanese Patent Application Laid-Open No. 58-87.
One or more selected from the group consisting of zinc oxide-cobalt oxide solid solution, zinc oxide-cobalt oxide-magnesium oxide solid solution, and zinc oxide-cobalt oxide-nickel oxide-titanium oxide solid solution described in Publication No. 161. A solid solution of can be used. The blending amount is 0 for Garanuku heavy lifting part.
．． The amount is 10 to 1.00 parts by weight, and if it is less than 0.810 parts by weight, there is no strength improvement effect, and if it exceeds 1.00 parts by weight, bleeding of the glass occurs, which is not preferable.

Bismuth oxide is added to increase the fluidity of the free binder and improve its adhesion to the substrate.
If it is less than 1.0 parts by weight, the solder wettability, solder resistance, and adhesive strength will be poor, and if it exceeds 5.0 parts by weight, the glass will float, resulting in poor solder wettability.

In the present invention, due to the action of these additives and the above-mentioned glass, there is very little vitreous material on the film surface, most of which is distributed on the substrate side and contributes to adhesion with the substrate. It is thought that it has a glass matrix structure, and has extremely good solder wettability and greatly improved adhesive strength, especially the strength after heat aging, which is much superior to conventional products. Further, even when the film thickness is thin, such a +ll structure can be easily formed, so that a conductor with high adhesive strength can be formed.

Furthermore, other additives blended in the second invention, namely chromium oxide, titanium oxide, and lead oxide, are effective when performing infrared high-speed firing. In other words, chromium oxide and titanium oxide suppress the excessive flow of the glass, and lead oxide has the effect of releasing gasifying components in the glass, so by combining these, the lifting, bleeding, and foaming of the glass can be prevented during high-speed firing. be done.

These additives do not necessarily need to be added when firing is performed in a normal Matsufuru furnace, but when firing is performed in an infrared high-speed firing furnace, the total amount of chromium oxide and titanium oxide is 0.02 to 0 per part of glass. , 30 parts by weight, lead oxide is 0.10
It is desirable to blend 1.00 parts by weight.

If the total amount of chromium oxide and titanium oxide exceeds 0.30 parts by weight, solder wettability deteriorates, and if more than 1.00 parts by weight of lead oxide is added, the fluidity of the glass becomes too high, which is not preferable.

Examples of conductive metal powders include noble metals such as AQ, ALI, Pd, and Pt, Qu,
Any base metal such as Ni can be used.

In the conductive composition, the free binder is conductive metal powder 10
0 parts by weight to 5 to 20 parts by weight.

The organic vehicle is not particularly limited as long as it is commonly used in thick film conductive compositions of this type.

Yuketsudan Next, the present invention will be specifically explained with reference to Examples.

The composition of the glass used in each Example and Comparative Example is as shown in Table 1. Note that X and Y are outside the scope of the present invention.

Table 1 Examples 1 to 14 Mixed powder of AC+ and Pd as conductive metal (weighted 8
Glasses A to D shown in Table 1 and other additives were added and mixed in the proportions shown in Table 2, and the mixture was dispersed in an organic vehicle to obtain a paste-like conductive composition. In addition, the Zn/CO solid solution in the additives in Table 2 is a zinc oxide-cobalt oxide solid solution, and zinc oxide 81-86
A solid solution consisting of 5-6% by weight of cobalt oxide and 9-11% by weight of magnesium oxide was used.

Each paste was fired on an alumina substrate to a film thickness of 12 mm.
A pattern of 1.5aaX L5rnm was screen printed to give 1JIn, and after drying at 150℃ for 10 minutes, the peak temperature was 850℃10 in a normal Matsufuru furnace.
A thick film conductor was formed by holding for 60 minutes and firing at a cycle of 60 minutes, and the following tests were conducted. The results are also shown in Table 2.

Solder wettability: A solder pole with a diameter of 1.5 rRrn was placed on the conductor film, and the spread rate of the solder ball was examined after leaving it in a solder bath at 230° C. for 30 seconds.

Initial adhesive strength: Solder plating with diameter o and sai on 4-body film!
After the Ii4 wire was soldered with tin-lead solder, the lead wire was pulled perpendicularly to the board, and the strength when the conductor was peeled off from the board was measured.

Adhesive strength after heat aging: The adhesive strength after aging at 150° C. for 100 hours was measured in the same manner as the initial strength.

Comparative Examples 1 to 6 The same 1-Pd fi composite powder as in the example, the glass and additives in Table 1 were added and mixed in the proportions shown in Table 3, and dispersed in a vehicle to form a paste-like conductive composition. I got it. Each was similarly baked onto an alumina substrate and its solder wettability and strength were measured. The results are shown in Table 3.

(Left below) [Adhesive strength test 1 with thin film thickness Next, Example 1.10. Each paste of Comparative Example 2 was fired on an alumina substrate so that the film thickness was 8 caps.
Screen printed a pattern of 1.5 rRm and heated at 150°C.
After drying for 10 minutes, a thick film conductor was formed by holding the peak temperature at 850° C. for 10 minutes and firing in a 60-minute cycle in a regular Matsufuru furnace. The solder wettability and adhesive strength of each conductor were measured, and the results are shown in Table 4. Comparison with the results in Table 2 shows that the film thickness dependence is small in the present invention, and sufficient adhesive strength is maintained even when the film is made thinner.

Table 4 [Infrared high-speed firing test] Next, each paste of the example and comparative example was screen printed on an alumina substrate so that the film thickness after firing was about 20M,
It was fired in an infrared firing furnace at a peak temperature of 880°C for a 20 minute cycle, and its appearance was examined. The results are × for those with glass floating, bleeding, or foaming on the surface.
1 Those in which these phenomena did not occur are indicated as O in Tables 2 and 3. This test clearly shows that the addition of chromium oxide and/or titanium oxide and lead oxide enables high-speed infrared firing.

KinriAs mentioned above, the conductive composition of the present invention not only has excellent solder wettability and adhesive strength with a substrate, especially adhesive strength after heat aging, compared to conventional ones, but also has a thin film thickness. However, since it has extremely high adhesive strength, the conductor can be made into a thin film, making it extremely suitable as a conductor material for high-density circuits. Furthermore, since the conductive composition containing chromium oxide, titanium oxide, and lead oxide can be fired at high speed in an infrared furnace, it has the advantage that the firing time can be greatly shortened.

Claims (1)

[Claims] 1. A conductive composition comprising a conductive metal powder and an inorganic binder dispersed in an organic vehicle, wherein the inorganic binder is (a) based on 100% by weight of the total of B_2O_3, ZnO and PbO. MoO_30.5-5.0% by weight, MnO
_20.5-3.0% by weight, TiO_20.5-3.0
(b) 1.0 to 5.0 parts by weight of bismuth oxide, (c) 0.10 to 1.00 parts by weight of manganese oxide, and (d
) A conductive composition comprising 0.10 to 1.00 parts by weight of one or more selected from zinc oxide-cobalt oxide solid solutions. 2. In a conductive composition in which a conductive metal powder and an inorganic binder are dispersed in an organic vehicle, the inorganic binder is (a) MoO_30.5 to 5 with respect to the total 100% by weight of B_2O_3, ZnO and PbO. .0% by weight, MnO
_20.5-3.0% by weight, TiO_20.5-3.0
(b) 1.0 to 5.0 parts by weight of bismuth oxide, (c) 0.10 to 1.00 parts by weight of manganese oxide, and (d) zinc oxide. -1 selected from cobalt oxide solid solutions
(e) 0.02 to 0.30 parts by weight of one or more oxides selected from chromium oxide and titanium oxide; (f) An electrically conductive composition comprising 0.10 to 1.00 parts by weight of lead oxide. 3. Claim 1 or 2, wherein the zinc oxide-cobalt oxide solid solution is a zinc oxide-cobalt oxide solid solution, a zinc oxide-cobalt oxide-magnesium oxide solid solution, or a zinc oxide-cobalt oxide-nickel oxide-titanium oxide solid solution. The conductive composition described in .