JPH0995705A - Silver-palladium coprecipitated powder and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a Ag-Pd coprecipitated powder small in formed grain size by a liq. phase reducing method without diluting a concn. of a metal ion in a metal ion-containing soln. SOLUTION: At the time of producing the Ag-Pd coprecipitated powder by mixing the metal ion-containing soln. containing Ag and Pd ions with a reducing agent-containing soln. and subjecting the mixture to the liq. phase reduction, the pHs of the metal ion-containing soln. and the reducing agent- containing soln. are adjusted. The Ag-Pd coprecipitated powder is obtained by mixing both soln.s after adjusting the ratio of pH(M) of the metal ion- containing soln. to pH(R) of the reducing agent-containing soln. in <=1.8 as one method or adjusting the difference between pH(M) and pH(R) in <=4.0 as the other method and by subjecting both to the liq. phase reduction to reduce and to precipitate simultaneously Ag and Pd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic ceramic parts such as ceramic capacitors, chip resistors and the like, circuit boards using ceramics such as ceramics circuit boards and other electronic parts when the conductors thereof are used as a conductor paste, for example. The present invention relates to an Ag-Pd coprecipitated powder suitable for forming by printing and firing, a method for producing the same, and a conductor paste.

[0002]

2. Description of the Related Art In manufacturing circuit boards and other electronic parts using ceramics, in forming conductors thereof, a noble metal conductor paste such as Ag is used.
Printing and firing are performed using a conductor paste of -Pg alloy powder.

In the production of the Ag-Pd alloy powder in this case, a metal ion-containing solution containing Ag ions and Pd ions and a reducing agent solution containing a reducing agent are mixed and Ag-by liquid phase reduction. A well-known method is a coprecipitation reduction method of reducing and precipitating a Pd coprecipitation powder (for example, Japanese Patent Publication No. 44-21968).

In such a coprecipitation reduction method,
When adjusting the generated particle size of the Ag-Pd coprecipitated powder, for example, it was controlled by the metal ion concentration in the metal ion-containing solution.

In this case, the product particle size A is large.
When trying to obtain a g-Pd coprecipitated powder, the metal ion concentration in the metal ion-containing solution is made to be high, and conversely, when trying to obtain an Ag-Pd coprecipitated powder having a small product particle size, The metal ion concentration in the solution was made thin.

On the other hand, the recent development trend of electronic parts is toward lighter, thinner, shorter and smaller devices. Therefore, the Ag-Pd powder used as the conductive material is also required to have a small particle size.

[0007]

As described above, in the prior art, Ag produced by liquid phase reduction has a small particle size.
When the -Pd coprecipitated powder is produced, the metal ion concentration in the metal ion-containing solution may be reduced, but the conventional equipment is used to produce the Ag-Pd coprecipitated powder having a small particle size. If this is attempted, there is a problem that the production efficiency is reduced.

When it is attempted to secure the same production amount in the production of Ag-Pd coprecipitated powder having a small particle size, it is necessary to install a larger reaction facility, which is not economical. was there.

Further, the powder containing Pd easily reacts with oxygen to generate PdO, and in this case, volume expansion occurs. Therefore, Ag-Pd coexisting which is hard to react with oxygen and hardly causes volume expansion occurs. There was a problem that it was desired to be a powder.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and it is possible to control the particle size of Ag-Pd coprecipitated powder produced without changing the conventional equipment. Therefore, the production efficiency does not decrease even when the Ag-Pd coprecipitated powder having a small particle size is produced, the same production amount can be secured by using the conventional equipment, and the particle size is small. Ag-Pd, which hardly causes oxidation
The purpose is to enable efficient production of a coprecipitated powder.

[0011]

SUMMARY OF THE INVENTION Ag-P according to the present invention
As described in claim 1, the method for producing the d-precipitated powder is carried out by liquid phase reduction by mixing a metal ion-containing solution containing Ag ions and Pd ions with a reducing agent-containing solution containing a reducing agent. When producing the Ag-Pd coprecipitated powder, the pH of the metal ion-containing solution is adjusted and the pH of the reducing agent-containing solution is adjusted, and the pH of the metal ion-containing solution (M) and the pH of the reducing agent-containing solution (R) are adjusted. Specific pH (M) / pH with
(R) is set to 1.8 or less and both solutions are mixed, and Ag and Pd are simultaneously reduced and precipitated by liquid phase reduction to obtain an Ag-Pd coprecipitated powder.

The method for producing the Ag-Pd coprecipitated powder according to the present invention also has the following features.
When a metal ion-containing solution containing Ag ions and Pd ions and a reducing agent-containing solution containing a reducing agent are mixed to produce an Ag-Pd coprecipitated powder by liquid phase reduction, the pH of the metal ion-containing solution is adjusted. Together with p of the reducing agent-containing solution
H was adjusted, and the difference between the pH (M) of the metal ion-containing solution and the pH (R) of the reducing agent-containing solution was adjusted to pH (M) -pH (R) of 4.0 or less, and both solutions were mixed to prepare a solution. Ag by phase reduction
By simultaneously reducing and precipitating Ag and Pd
d Co-precipitated powder is obtained.

In an embodiment of the method for producing the Ag-Pd coprecipitated powder according to the present invention, as described in claim 3, when adjusting the pH of the metal ion-containing solution, a pH adjusting agent is used. Ammonia or ammonium hydroxide can be used.

Similarly, in an embodiment of the method for producing an Ag-Pd coprecipitated powder according to the present invention, as described in claim 4, an ammonia compound such as ammonium formate is used as the reducing agent of the reducing agent-containing solution. Hydration hydrazine,
It is possible to use a reducing agent selected from hydrazine compounds such as hydrazine hydrochloride, and as described in claim 5, when adjusting the pH of the reducing agent-containing solution, a reducing agent is used. , Nitric acid, ammonia or ammonium hydroxide can be used.

Similarly, in an embodiment of the method for producing an Ag-Pd coprecipitated powder according to the present invention, as described in claim 6, at least one of the metal ion-containing solution and the reducing agent-containing solution, Ammonia compounds such as ammonium nitrate, ammonium acetate, and ammonium carbonate can be added as a buffer when the two solutions are mixed.

The Ag-Pd coprecipitated powder according to the present invention has the pH (M) of a metal ion-containing solution containing Ag ions and Pd ions, as described in claim 7.
Specific pH with the pH (R) of the reducing agent-containing solution containing the reducing agent
It is characterized in that it is formed by reduction precipitation in a mixed solution of both solutions in which (M) / pH (R) is 1.8 or less.

The Ag-Pd coprecipitated powder according to the present invention also has the pH of a metal ion-containing solution containing Ag ions and Pd ions, as described in claim 8.
The difference between (M) and the pH (R) of the reducing agent-containing solution containing the reducing agent is formed by reducing and precipitating in a mixed solution of both solutions having a pH (M) -pH (R) of 4.0 or less. It is characterized by having been made.

In the embodiment of the Ag-Pd co-precipitated powder according to the present invention, as described in claim 9, the produced particle size is 0.1 to 0.5 μm. It has a feature.

Further, the conductor circuit forming conductor paste according to the present invention is, as described in claim 10, a paste form of the Ag-Pd coprecipitated powder according to any one of claims 7 to 9. It is characterized by having done.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A method for producing an Ag-Pd coprecipitated powder according to the present invention comprises a metal ion-containing solution containing Ag ions and Pd ions, as described in claims 1 and 2. When a reducing agent-containing solution containing a reducing agent is mixed to produce an Ag-Pd coprecipitated powder by liquid phase reduction, the pH of the metal ion-containing solution is adjusted and the pH of the reducing agent-containing solution is adjusted. The method according to 1, wherein the ratio (M) / pH (R) of the pH (M) of the metal ion-containing solution and the pH (R) of the reducing agent-containing solution is set to 1.8 or less, and both solutions are mixed. The method according to claim 2, wherein Ag and Pd are simultaneously reduced and precipitated by liquid phase reduction.
As the method described in 1, the pH of the metal ion-containing solution (M)
And pH of reducing agent-containing solution (R) difference pH (M) -pH
(R) is adjusted to 4.0 or less, both solutions are mixed, and Ag and Pd are simultaneously reduced and precipitated by liquid phase reduction to obtain an Ag-Pd coprecipitated powder.

When carrying out the present invention, as described in claim 3, the p of the metal ion-containing solution is added.
When adjusting H, ammonia or ammonium hydroxide can be used as a pH adjuster, whereby the ratio of the pH of the metal ion-containing solution (M) to the pH of the reducing agent-containing solution (R) can be adjusted. pH (M) / pH
(R) should be 1.8 or less, or the pH (M) of the metal ion-containing solution and the pH (R) of the reducing agent-containing solution
The difference pH (M) -pH (R) is set to 4.0 or less.

Further, as described in claim 4, a reducing agent selected from ammonia compounds such as ammonium formate, hydrazine hydrate and hydrazine compounds such as hydrazine hydrochloride is used as the reducing agent for the reducing agent-containing solution. By using it, the Ag salt and the Pd salt are simultaneously reduced by the liquid phase reduction and deposited as an Ag-Pd coprecipitated powder.

Then, as described in claim 5,
When adjusting the pH of the reducing agent-containing solution, nitric acid, ammonia, or ammonium hydroxide can be used as a pH adjusting agent, whereby the pH (M) of the metal ion-containing solution and the reducing agent-containing solution can be adjusted. PH of
The specific pH (M) / pH (R) with (R) is set to 1.8 or less, or the pH (M) of the metal ion-containing solution
And pH of reducing agent-containing solution (R) difference pH (M) -pH
(R) is adjusted to 4.0 or less so that Ag particles having a small particle size can be produced without controlling the metal ion concentration in the metal ion-containing solution, particularly without decreasing the metal ion concentration. It becomes possible to obtain a -Pd coprecipitated powder.

Further, as described in claim 6,
When a metal ion-containing solution and a reducing agent-containing solution are mixed by adding an ammonia compound such as ammonium nitrate, ammonium acetate, or ammonium carbonate to at least one of the metal ion-containing solution and the reducing agent-containing solution. It functions as a buffering agent, and the reduction reaction of Ag ions and Pd ions with the reducing agent is buffer-controlled in the reduction precipitation reaction that occurs when both solutions are mixed. It is possible to obtain a Ag-Pd co-precipitated powder in which the Ag-Pd co-precipitated powder is uniformly mixed, and when printing a conductor paste in which the Ag-Pd co-precipitated powder in which the Ag component and the Pd component are uniformly mixed is made into a paste form. The printability of the product is remarkably improved, and the increase in the amount of oxidation during baking after printing is small, causing problems such as volume expansion and cracking. It is possible to obtain a pair circuit forming conductor.

And, as described in claim 9,
By setting the generated particle size to be 0.1 to 0.5 μm, as described above, it is possible to surely improve the printability of the conductor paste using the Ag-Pd coprecipitated powder. In addition to being possible, it becomes possible to more reliably prevent an increase in the amount of oxidation (volume expansion) due to the reaction of Pd with oxygen to form PdO during firing, and circuit boards using ceramics, etc. It is possible to prevent cracks from occurring in the conductor (1), and it is possible to form a high quality conductor.

[0026]

Examples Example 1 Ag ions of 0.07 g / cc and Pd ions of 0.
Containing 03 g / cc, 0.5 g / cc of ammonium carbonate as an ammonia compound serving as a buffer when mixing two solutions
In addition, in a metal ion-containing solution containing ammonium nitrate in an amount of 0.5 g / cc, a required amount of ammonium hydroxide was mixed as a pH adjusting solution to adjust the pH (M) of the metal ion-containing solution to 8.0 to 10.0. Adjusted in the range.

On the other hand, as a reducing agent, 0.017 g / cc of ammonium formate and 3.7 × 10 5 of hydrazine hydrate are used.
^-3 g / cc, and ammonium nitrate 0.05 g / c as an ammonia compound serving as a buffer when mixing two solutions
c and ammonium acetate in an amount of 0.05 g / cc in some cases, a required amount of ammonium hydroxide or nitric acid was mixed as a pH adjusting solution to adjust the pH (M) of the reducing agent-containing solution to 2.5 to It was adjusted in the range of 10.0.

Next, the pH (M) of the metal ion-containing solution
PH of the solution containing the reducing agent (R), pH (M) / pH
Both solutions were mixed in such a ratio that (R) had a value shown by the horizontal axis in FIG. 1, and Ag and Pd were simultaneously reduced and precipitated by liquid phase reduction to obtain an Ag-Pd coprecipitated powder.

Then, the pH (M) of the metal ion-containing solution
PH of the solution containing the reducing agent (R), pH (M) / pH
When the influence of (R) on the particle size of the coprecipitated powder of Ag-Pd was examined, the particle size of the coprecipitated powder was also as shown on the vertical axis in FIG. 1.

As a result, in order to make the particle size of the Ag-Pd coprecipitated powder more preferably 0.5 μm or less, the ratio expressed by pH (M) / pH (R) is It was found that it is desirable to set it to 1.8 or less.

Then, as shown in FIG. 2, the production particle size of the Ag-Pd co-precipitated powder is more preferably set to 0.5 μm or less to print a conductor paste containing the Ag-Pd co-precipitated powder. After that, for example, it is possible to reduce the amount of increase in oxidation when fired at 300 ° C. to about 4% by weight or less, so that the amount of increase in oxidation is small, that is, the volume expansion amount is small, and cracks or conduction defects are caused in a ceramic circuit board or the like. It was possible to obtain an Ag-Pd co-precipitated powder capable of producing a ceramic circuit board and other electronic components with excellent quality which are hard to occur.

Example 2 Ag ions of 0.07 g / cc and Pd ions of 0.
Containing 03 g / cc, 0.5 g / cc of ammonium carbonate as an ammonia compound serving as a buffer when mixing two solutions
In addition, in a metal ion-containing solution containing 0.5 g / cc of ammonium nitrate as the case may be, a required amount of ammonium hydroxide is mixed as a pH adjusting solution to adjust the pH (M) of the metal ion-containing solution to 8.0 to 10.0. Adjusted in the range.

On the other hand, as a reducing agent, 0.017 g / cc of ammonium formate and 3.7 × 10 5 of hydrazine hydrate are used.
^-3 g / cc, and ammonium nitrate 0.5 g / cc as an ammonia compound serving as a buffer when mixing two solutions
And ammonium acetate in an amount of 0.5 g / cc, if necessary, ammonium hydroxide or nitric acid was mixed as a pH adjusting solution in a required amount to adjust the pH (M) of the reducing agent-containing solution to 2.5 to 9 It was adjusted in the range of 0.0.

Next, the pH (M) of the metal ion-containing solution
And pH of reducing agent-containing solution (R) difference pH (M) -pH
Both solutions were mixed in such a ratio that (R) had a value shown by the horizontal axis in FIG. 3, and Ag and Pd were simultaneously reduced and precipitated by liquid phase reduction to obtain an Ag-Pd coprecipitated powder.

Then, the pH (M) of the metal ion-containing solution
And pH of reducing agent-containing solution (R) difference pH (M) -pH
When the effect of (R) on the particle size of the coprecipitated powder of Ag-Pd was examined, the particle size of the coprecipitated powder was also as shown on the vertical axis in FIG. 3.

As a result, the difference expressed by pH (M) -pH (R) should be adjusted in order to make the particle size of the Ag-Pd coprecipitated powder more preferably 0.5 μm or less. It has been confirmed that it is desirable to set it to 4.0 or less.

Then, as shown in FIG. 2, Ag-Pd
By making the particle size of the coprecipitated powder to be 0.5 μm or less, it is possible to increase the oxidation weight gain by about 4 in the same manner as described above.
Manufacture of high-quality ceramic circuit boards and other electronic parts that can be reduced to less than 10% by weight and have a small amount of increase in oxidation, that is, a small volume expansion amount, which is unlikely to cause cracks or defective conduction in ceramic circuit boards. It was possible to obtain an Ag-Pd co-precipitated powder that can be obtained.

[0038]

Industrial Applicability The method for producing an Ag-Pd coprecipitated powder according to the present invention comprises performing a liquid phase reduction by mixing a metal ion-containing solution containing Ag ions and Pd ions with a reducing agent-containing solution containing a reducing agent. In producing the Ag-Pd coprecipitated powder, the pH of the metal ion-containing solution is adjusted and the pH of the reducing agent-containing solution is adjusted, and one method is to adjust the pH (M) of the metal ion-containing solution and the reducing agent-containing solution. Another method of achieving the same purpose is to reduce both the pH (M) and the pH (R) of the metal ion-containing solution by reducing the specific pH (M) / pH (R) to 1.8 or less and mixing both solutions. PH of agent-containing solution (R)
The difference pH (M) -pH (R) is adjusted to 4.0 or less, both solutions are mixed, and Ag and Pd are subjected to liquid phase reduction in both methods.
Since the Ag-Pd coprecipitated powder was obtained by simultaneously reducing and precipitating, the conventional equipment was used without controlling the metal ion concentration in the metal ion-containing solution as in the conventional case. It is possible to control the generated particle size of the Ag-Pd co-precipitated powder, and the production efficiency does not decrease when manufacturing the Ag-Pd co-precipitated powder with a small generated particle size. It is possible to secure the production amount, and it is possible to efficiently produce an Ag-Pd coprecipitated powder having a small particle size, and to obtain a fine-grained Ag-Pd coprecipitated powder having a uniform particle size. By being able to manufacture, it is possible to further improve the printability of the conductor paste using this coprecipitated powder on a ceramic substrate or the like, and at the time of firing after printing. It is possible to assume that hardly cause reduction and volume expansion, leading to significantly excellent effect that it is possible to form a high conductive circuit reliability.

[Brief description of drawings]

FIG. 1 is a ratio of the pH of a solution containing a metal ion (M) to the pH of a solution containing a reducing agent (R), which is Ag (pH) / pH (R).
7 is a graph illustrating the results of examining the effect on the particle size of Pd co-precipitated powder.

FIG. 2 is a graph illustrating the results of examining the effect of the particle size of the Ag-Pd co-precipitated powder produced during calcination on the amount of oxidation increase.

FIG. 3 shows the difference between the pH (M) of the metal ion-containing solution and the pH (R) of the reducing agent-containing solution, and the Ag of pH (M) -pH (R).
7 is a graph illustrating the results of examining the effect on the particle size of Pd co-precipitated powder.

Claims (10)

[Claims] 1. A metal ion-containing solution when a metal ion-containing solution containing Ag ions and Pd ions and a reducing agent-containing solution containing a reducing agent are mixed to produce an Ag-Pd coprecipitated powder by liquid-phase reduction. The pH of the reducing agent-containing solution and the pH of the metal ion-containing solution.
Specific pH (M) between (M) and the pH (R) of the reducing agent-containing solution
/ PH (R) is set to 1.8 or less, both solutions are mixed, and Ag-Pd coprecipitated powder is obtained by simultaneously reducing and precipitating Ag and Pd by liquid phase reduction.
-The manufacturing method of Pd coprecipitation powder. 2. A metal ion-containing solution when a metal ion-containing solution containing Ag ions and Pd ions and a reducing agent-containing solution containing a reducing agent are mixed to produce an Ag-Pd coprecipitated powder by liquid phase reduction. The pH of the reducing agent-containing solution and the pH of the metal ion-containing solution.
(M) and the pH (R) of the reducing agent-containing solution pH (M)
-Ag-Pd coprecipitated powder is obtained by mixing both solutions with a pH (R) of 4.0 or less and simultaneously reducing and precipitating Ag and Pd by liquid-phase reduction.
-The manufacturing method of Pd coprecipitation powder. 3. The Ag-P according to claim 1, wherein ammonia or ammonium hydroxide is used as a pH adjusting agent when adjusting the pH of the metal ion-containing solution.
d Method for producing coprecipitated powder. 4. As a reducing agent for a reducing agent-containing solution, an ammonia compound such as ammonium formate, hydrazine hydrate,
The method for producing an Ag-Pd coprecipitated powder according to claim 1, wherein a reducing agent selected from hydrazine compounds such as hydrazine hydrochloride is used. 5. The method for producing an Ag-Pd coprecipitated powder according to claim 1, wherein nitric acid, ammonia or ammonium hydroxide is used as a pH adjuster when adjusting the pH of the reducing agent-containing solution. . 6. The Ag—Pd according to claim 1, wherein an ammonia compound such as ammonium nitrate, ammonium acetate or ammonium carbonate is added to at least one of the metal ion-containing solution and the reducing agent-containing solution.
Method for producing coprecipitated powder. 7. A ratio pH (M) / pH (R) of the pH (M) of a metal ion-containing solution containing Ag ions and Pd ions and the pH (R) of a reducing agent-containing solution containing a reducing agent is 1 A Ag-Pd coprecipitated powder, which is formed by reduction precipitation in a mixed solution of both solutions having a ratio of 0.8 or less. 8. The difference between the pH (M) of the metal ion-containing solution containing Ag ions and Pd ions and the pH (R) of the reducing agent-containing solution containing a reducing agent is 4 (pH). An Ag-Pd co-precipitated powder, which is formed by reduction precipitation in a mixed solution of both solutions adjusted to 0.0 or less. 9. The Ag-Pd coprecipitated powder according to claim 7, which has a generated particle size of 0.1 to 0.5 μm. 10. A conductor having good printability during pattern formation and a small increase in oxidation during firing, characterized in that the Ag-Pd coprecipitated powder according to any one of claims 7 to 9 is formed into a paste. Conductor paste for circuit formation.