JPS61245406A - Conducting paste - 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 INDUSTRIAL APPLICATION The present invention relates to pastes for cerdip substrates, in particular to drading pastes.

BACKGROUND OF THE INVENTION In recent years, electronic devices have become significantly thinner and more compact, and as the degree of integration has increased, reliability has further improved, and applications have continued to expand. Monolithic ICs are rapidly increasing in density and becoming smaller, while hybrid ICs
In the field of C, there is a strong trend toward large-scale hybrid ICs with excellent heat resistance and thermal shock resistance, especially in industrial equipment such as automotive control circuits and power supply devices. It is equipped with active components such as diodes, transistors, and semiconductor ICs, as well as most electrical components such as coils, transformers, and capacitors. Hybrid integrated circuits have been developed that have further increased the degree of integration and have dramatically improved reliability.

These hybrid ICs are constructed by mounting individual components or IC elements on a ceramic substrate, or by making full use of thick film technology. Sardipue C is usually AQ
A silicon IC chip is fixed onto a 20392-88% alumina substrate using a bonding paste, but a more durable bonding force is required.

Usually, Au-based paste, solder, glass, etc. are used as a bonding method for the cerdip. A
U-based paste has excellent conductivity, is completely chemically stable, and has the best bondability with Au wire.
It easily alloys with Si, has very good adhesion to the substrate, and has particularly excellent reliability, but it has the drawback of being expensive. To solve this problem, an Ag-Pd paste has been developed in which Au is replaced with Ag and Pd is added to prevent migration, which is a disadvantage of Ag.

These conventional pastes are made by mixing metal powder with a glassy metal oxide and kneading the mixture using a vehicle, and the adhesion to the alumina substrate relies mostly on sintered bonding of the glass frit.

However, glass frit is susceptible to thermal shock, and has the disadvantage that its adhesive strength deteriorates due to heat during the process of baking and packaging the substrate, or due to changes in environmental temperature during use. In order to improve the adhesive strength with the alumina substrate, attempts have been made to chemically bond with the alumina substrate by adding a small amount of Cu, etc. However, as long as glass frit is used, the thermal deterioration characteristics are dramatically improved. was difficult.

In other words, if Cu fine powder is simply added, a phenomenon will occur in which the fine Cu powder will be separated from other fine metal powders due to the difference in specific gravity in the vehicle, resulting in poor dispersion during drudging, and not only will a uniform metallized film not be obtained. Since it is not sufficiently diffused into the alumina substrate, the adhesive strength of the film becomes insufficient. In addition, there is a drawback that areas where Cu is segregated during the firing process are locally oxidized and colored, making it impossible to obtain a film with a uniform and smooth surface.

In order to solve the problems that the invention aims to solve, such as the drawbacks listed in (h), an attempt was made to provide a paste using a composite powder of silver and copper without using a frit.

However, if copper is added as a metal, it is likely to cause segregation, and if such a paste is used, there will be large variations in adhesive strength, making it difficult to obtain a stable product.

Means and Effects for Solving the Problem The present inventors have previously proposed a conductive paste characterized by using a composite fine powder of silver (Ag) and copper (Cu) and adding yttrium oxide. Gansho 59-207042
), the present invention aims to improve the dispersibility of copper and stably strengthen the adhesive strength by further adding organic copper to the above proposal. The first invention is silver fine powder,
The gist is that the paste contains a composite fine powder of silver and copper and a copper organic substance in such a range that the total amount of copper wire in the paste is 0.10%, and the remainder is a vehicle. The second invention contains a silver fine powder, a composite fine powder of silver and copper, a composite fine powder of silver and platinum, or a fine platinum powder, and further contains a copper organic substance in which the total of copper wires in the paste is 0. .1 to 10%, with the remainder being vehicle to prevent Ag migration.

This has the effect of improving wire adhesion and solder properties.

The third invention contains a fine silver powder, a fine composite powder of silver and copper, a fine composite powder of silver and palladium, or a fine palladium powder, and further contains a copper organic substance in which the total amount of copper wire in the paste is The content is in the range of 0.1 to 10%, with the remainder being vehicle, and is particularly effective in preventing migration of Ag, and has the effect of improving wire adhesion and soldering properties.

Next, the present invention will be explained in detail. In the present invention, the fine silver powder has a particle size of 10 pLI11 or less, preferably an average particle size (
A layer with a Dso ) of 0.5 to 5μ is used.

If it is larger than 1 OIL11, the dispersibility in the vehicle will be poor and there is a risk that the needle will be clogged during dotting. Furthermore, it becomes difficult to obtain a smooth finished fired surface. The silver powder does not need to be special, and silver powder obtained by a normal reduction method or electrolytic method can be used.

The composite fine powder of silver and copper only needs to maintain a bond between the silver particles and the copper particles in the vehicle, and plating powder, co-precipitated powder, mechanical alloy powder, etc. can be used. In particular, mechanical alloy powder is the result of mixing and pulverizing silver and copper powders by rotating them at high speed in a ball mill, and the silver particles and copper particles are mechanically interlocked and bonded, and no binder is used. It is possible to maintain a strong bond between silver particles and copper particles without causing any damage. When mechanical alloy powder is used, it has the advantage that composite powders having a wide range of Cu contents can be arbitrarily selected and used. The particle size of the composite powder of silver and copper is 10gn+ or less,
Preferably, the average particle size (Dy+) is 0.5 to 5 pm, and the copper content in the silver and copper composite powder is 20 to 5 pm.
85% is appropriate. If the copper content is less than 20%, the film strength will not be sufficient, and if it exceeds 95%, the effect of forming a composite powder will be lost. Further, it is desirable that the specific gravity value be as close as possible to an intermediate value between that of silver and copper in order to improve dispersibility in the vehicle.

The copper content in the metal powder in the conductive paste is 0.1
-10%, preferably 2-5%. Copper content is 0.
If the copper content is less than 1%, the diffusion into the alumina will be insufficient and the adhesive strength will not increase.If the copper content exceeds 10%, the oxidation of copper will become significant, which will even have an adverse effect.

The metal powder content in the conductive paste must be 60 to 90%; otherwise, a paste viscosity that is easy to handle cannot be obtained.

The copper organic substance used in the present invention is represented by the general formula 0 0 U (R is a saturated hydrocarbon), and is a cyclic terpene derivative or R-9-Cu or R-5-Cu-5- It may be represented by the general formula R, and the copper content is generally 3
~10% by weight. in particular.

Examples include copper resinate, copper aryl mercaptide, and copper erpenmethide. These organic coppers exist in a state dissolved in a solvent in the paste. Organic copper.

IR method (Infra-Red Absorption)
Spectrum, infrared absorption spectrum), NMR method (Nuclear Magnetic Resonance)
Its presence can be determined by distinguishing it from metallic copper using methods such as e-nuclear magnetic resonance.

The effects of using a copper organic substance are as follows: i) Since it is a liquid, it mixes well with the vehicle, making it possible to form a paste with excellent dispersibility.

ii) There is almost no segregation even when dotted on a substrate.

1ii) In the firing process, the Ag/Cu composite powder mainly contributes to the adhesive strength with the substrate, and the copper organic matter is uniformly dispersed, which promotes sintering between the metallized layers. ffi
Therefore, variations in adhesive strength are reduced, and a product with stable strength can be obtained.

The vehicle has the function of uniformly dispersing the fine powder, has appropriate viscosity and surface tension when used, and has the function of smoothly dispersing it on the applied surface.The vehicle used in the present invention is made of commonly used ethyl cellulose as a binder. As,
Organic solvents such as terpineol, butylcarpitol, butylcarpitol acetate, and texanol can be used as the solvent. Further, in order to improve wettability with metal powder, adding 0.5 to 10% of a surfactant improves dispersibility. In addition, 0.1 to 2% of rosin resin is used as a dispersant.
It may also be added. In the paste state, the viscosity should be adjusted high to avoid separation and segregation of fine metal powder particles.
When using, dilute with a solvent and 40 to 450 c.
Adjust the viscosity to ps.

The first invention includes a fine silver powder and a composite fine powder of silver and copper, the total of these fine metal powder particles is 60 to 90%, and the content of copper in the fine metal powder is 0.1- 10%, and furthermore, the total amount of pure copper in the paste with copper organic matter is 0.
It is a conductive paste consisting of 1 to 10% of 1 and the remainder of the vehicle.

By configuring the paste as described above, it can withstand thermal shock and has strong bonding strength with significantly improved thermal deterioration resistance. Furthermore, the paste according to the present invention has good dispersibility during dotting, resulting in an excellent surface film having smooth and uniform baked clay properties.

The second invention is the first invention with platinum added,
Contains fine silver powder, fine composite powder of silver and copper, fine composite powder of silver and platinum or fine platinum powder, the total of these fine metal powder particles is 60 to 90%, and fine metal powder The content of copper in the paste is 0.1 to 10%, and if it is a composite powder with silver, the content of platinum is 0.2 to 30%, and the total amount of pure copper in the paste is 0.2 to 30%. It is a conductive paste containing 0.1 to 1o% of 0.1% to 10%, with the remainder being vehicle. By configuring the paste as above,
In addition to having strong bonding strength that can withstand thermal shock and significantly improved thermal deterioration resistance, it also has the effect of preventing silver migration and improving wire bonding properties, fine line properties, solder properties, and electrical conductivity. Furthermore, when connecting a wire to a part of the cavity, an Al wire has the great advantage of being usable.

Since platinum is chemically stable, it is effective to improve the above properties even when mixed alone, but using a composite powder with silver is even more effective because it is uniformly dispersed in the vehicle. As the composite powder of silver and platinum, plating powder, co-precipitated powder, mechanical alloy powder, etc. can be used. A suitable platinum content in the composite powder is 5 to 60%. Mechanical alloy powders with high platinum content can be easily obtained. The powder particle size of the composite powder is 1 OIL11 or less, the average particle size (Ds
o) is preferably about 5 gm or less, and the platinum content is 0.2 to 10%, preferably 0.5 to 3.0%, based on the metal particles in the paste. If the platinum content is 0.2% or less, no effect of addition is observed, and if the platinum content is 10% or more, no cost reduction effect appears.

The third invention is the first invention with the addition of palladium, and includes a fine silver powder, a composite powder of silver and copper, a fine composite powder of silver and palladium, or a fine palladium powder. The total amount of fine metal powder particles is 60 to 60%, and the content of copper in the fine metal powder is 0.1 to 10%, the content of palladium is 0.2 to 30%, and the content of copper organic matter is 0.1 to 10%. It is a conductive paste containing a total of 0.1 to 10% of pure copper in the paste, with the remainder being a vehicle. By configuring the paste as described above, it not only has a strong bonding strength that can withstand thermal shock and has significantly improved thermal deterioration resistance, but also has a remarkable effect on preventing silver migration, and has wire bonding properties. It has the effect of improving solder properties and producing a smooth, homogeneous film on the surface.

It is a widely known fact that pastes containing palladium have the effect of preventing silver migration, but in pastes containing only palladium, the palladium is easily oxidized during the firing process, resulting in extreme surface roughness. It has the disadvantage of becoming rough. Therefore, when palladium is added alone, it is necessary to use a fine powder with a particle size (Dso) of 2 gta or less. In the present invention, by using a powder that is a composite of palladium and silver, oxidation of palladium can be prevented. It has been found that a film with an extremely good planar state can be obtained.

Co-precipitation powder, mechanical alloy powder, and plating powder can be used as the composite powder of silver and palladium. The palladium content in the composite powder is 10-40%, preferably 2
0 to 30% is easy to use.

The particle size of the composite powder is 10 ILffi or less, the average particle size (
D! lo) should be approximately 54 m or less.

The palladium content is 0 relative to the metal particles in the paste.
．． It is 2-30%, preferably 0.5-10%. This is because if the palladium content is less than 0.2%, the effect of addition is not recognized, and even if it is added in an amount of 30% or more, no significant improvement in properties can be expected.

In these inventions, the advantages of blending the copper organic substance are that it is liquid and can be mixed very well with the vehicle;
It has the advantage of not separating or segregation during dotting, and has the advantage of maintaining high and stable strength after firing.

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

A paste was prepared by using the metal powder shown in Table 1 and kneading it in a three-roll mill using terpineol containing organic copper as a vehicle, ethyl cellulose, and a surfactant.

A commercially available reduced silver powder was used, with a purity of 99.9% and a particle size of 1 to 4 square meters.

A mechanical alloy powder obtained by mixing and pulverizing 90% silver powder and lθ% copper powder in a ball mill at high speed was used as a composite powder of silver and copper. The particle size of the composite powder was classified to 10 ILm or less.

As platinum, a commercially available fine powder of 0.5 to 0.8 p, ta and a coprecipitated powder with a ratio of silver and platinum of 85:15 were used by dispersing them into 5 servings or less.

Palladium is commercially available with a particle size of 0.8 to 1. A fine powder of 8JL powder and a co-precipitated powder having a weight ratio of silver and palladium of 7:3 were dispersed in an amount of 5 kg or less.

The vehicle components used were 12% ethyl cellulose based on terpineol, 2.5% nonionic surfactant, and resinate copper added in advance as a copper organic substance.

The vehicle component and resinate copper were blended in proportions such that the vehicle component was 11 parts by weight and the resinate copper was 4 parts by weight based on the entire paste.

Since the Cu content in the resinate steel is 8.4%, the pure Cu content from the resinate copper is 0.2513 parts by weight.

These metal powders, vehicle and resinate copper were sufficiently kneaded using a Miki roll mill under the compounding conditions shown in Table 1 to obtain a paste. The viscosity at that time is Brookf 1
When measured using an eld viscometer HBT using spindle No. 14, it was 200±50 Kcps.

Next, the paste was adjusted to a final viscosity of about 100 cps using a solution of butyl calpitol and terpineol mixed in a ratio of 1=1 as a thinner, and used for drudging.

The substrate is black alumina (92% AJ1203, size 3
1.7X 13X 2 am) and the cavity dimensions were 8.25X 8.25X O, 18 m+s.

The alumina substrate was used after cleaning with trichlorolene. A diluted paste whose viscosity was adjusted was applied dropwise onto this cavity by drudging.

The dorading device used was the one manufactured by Engineering Corporation in the lower right corner. After the conductive paste was dredged and leveled for 1 hour, it was dried at 120° C. for 20 minutes, and then fired in an atmospheric atmosphere using a 4MC type thick film firing furnace manufactured by Watkins Johnson. The firing conditions were a 60 minute profile with peak temperatures of 810°C and 920°C for 10 minutes.

The surface of the paste film thus obtained was observed, and the surface roughness was measured using a surface roughness meter manufactured by Tokyo Seimitsu. Fifty samples were used for each level.

Further, using an Au preform of 2.5×2.5+ua opening×25 pm, a silicon chip was bonded at 450° C. using a die attach device manufactured by West Pond. Characteristic tests were conducted on the thus obtained cerdip IC. These results are shown in Table 2.

Adhesive strength was determined by die attachability and Guibtsch test. Die attachability is determined by the scribing time during adhesion, and the mark Q in Table 1 and Table 2 indicates that the bonding was possible in a short time. The Guibutsch test was performed using a vertical pound tester manufactured by Engineered Technical Products Co., Ltd. on the test piece after the SA test was completed.Table 2
A middle ○ mark indicates that all 20 test pieces have broken, a Δ mark indicates that even one of the 20 samples has peeled off the film, and an X mark indicates that all 20 test pieces have peeled off the film. This indicates that it has been peeled off.

For the above heat resistance test, a thermal cycle test and a thermal shock test were conducted. The test conditions are ILL-ST for thermal cycle test.
C0NDITIO pursuant to D 883B 1010.2
It was done in NC. Thermal shock test is the same < MIL
L-9TD883B 1011 @2, C0ND
This was done with ITION C.

The vertical tensile strength of the fired metallized film was measured using the following method. First, add 104 m to the tip 2.85 copper studs in the intestinal layer.
Gold-silicon composite is silver-plated to a thickness of .

Using gold foil (2.2m x 2.2mm x 50μ, +) as a preform, adhere silver plating studs while scribing at 450°C.Then, pull the silver plating studs at a constant speed of 11m*/min. The vertical pull strength was measured using a Bush Pull Tester manufactured by Today Seisakusho.

As is clear from the results in Table 2, the conductive paste according to the present invention added with organic copper has an extremely smooth surface after firing, and the adhesive strength between the silicon chip and the fired metallized film is strong and stable with little variation. Moreover, it exhibits an extremely excellent effect in that the adhesive strength does not deteriorate even when subjected to thermal history. Further, when using the paste, it has the advantage that the copper content is well dispersed, homogeneous, and easy to handle.

On the other hand, when using a copper softener alone or adding silver or copper alone, the adhesive strength is not sufficient and the strength varies widely.

It was found that conductive pastes using platinum powder or silver-platinum composite powder have a good baked-on film, further improve adhesive strength, and do not deteriorate due to thermal history.

The bonding resistance value of the product of the present invention is extremely low, stable over time, and has good bonding characteristics.
The ability to use aluminum wire is also a major advantage of the present invention.

When the mixed powder of silver and palladium according to the present invention is used, these drawbacks are eliminated and the adhesive strength becomes even better.

(Margin below) Procedural amendment (voluntary) March 7, 1981

Claims (1)

[Scope of Claims] 1) The total amount of these metal fine powders is 60 to 90% (weight %, the same shall apply hereinafter), including fine silver powder and composite fine powder of silver and copper, and Copper content is 0.1-10%
A conductive paste, further comprising a copper organic substance in an amount such that the total amount of pure copper in the paste is 0.1 to 10%, and the remainder is a vehicle component. 2) Contains a fine silver powder, a fine composite powder of silver and copper, a fine composite powder of silver and platinum, or a fine platinum powder, the total of these fine metal powders being 60 to 90%, and a fine metal powder. The copper content in the powder is 0.1-10% and the platinum content is 0.2-10%.
10%, and further contains an organic copper substance in a range such that the total amount of pure copper in the paste is 0.1 to 10%, and the remainder is a vehicle component. 3) Contains fine silver powder, fine composite powder of silver and copper, fine composite powder of silver and palladium, or fine palladium powder, the total of these fine metal powders is 60 to 90%, and fine metal powder The content of copper in the paste is 0.1 to 10%, the content of palladium is 0.2 to 30%, and the total amount of pure copper in the paste is 0.1 to 10%. 1. A conductive paste comprising a vehicle component, with the remainder being a vehicle component.