JPH0417601A - Manufacture of metal powder aggregate for packing via hole - Google Patents

Abstract

PURPOSE:To manufacture the above metal powder aggregate which can be satisfactorily packed in via holes by removing solvent after kneading the metal powder aggregate and organo metal compound with solvent, crushing the obtd. kneaded body and executing reforming to each crushed powder. CONSTITUTION:After kneading the copper powder aggregate and titanium coupling agent with methyl ketone, the metyl ethyl ketone is removed from the kneaded body. Successively, this solvent-removed kneaded body 38 is charged in an upper vessel part 83 in a vibrating mill 80, and vibration movement is executed while stopping a vibrator 82 at each prescribed time to execute crushing, and the material crushed to <= about 100 mesh is collected into a lower vessel part 84 through a filter 85. The crushed copper powder aggregate 90 is formed by applying the titanium coupling agent on the copper powder and fed to surface deforming process to execute the surface deformation with the ordinary method. By this method, the metal powder aggregate, which can be satisfactorily packed in the via holes, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing metal powder for filling via holes.

Generally, ceramic printed wiring boards are manufactured by forming vias on a green sheet (step 1), then forming a conductor pattern (step 2), then laminating the green sheets (step 3), as shown in FIG. It is manufactured by firing this, step 4), and finally forming a surface semiconductor layer (step 5).

As shown in FIG. 7, the buyer 9 places an aggregate 13 of surface-modified copper powder 12 manufactured as described later on the top surface of the green sheet 11 in which the pie hole 10 is formed, and moves the squeegee 14 along the arrow. It is manufactured by moving copper powder 12 in 15 directions and filling via hole 10 with copper powder 12.

By sufficiently filling the via hole 10 with the copper powder 12, a high quality via 9 is formed.

Insufficient filling will result in voids.

There is a relationship between the quality of the formed via 9 and the copper powder 12 filled.

That is, in order for the copper powder 12 to be sufficiently filled in the pipe hole IO, the copper powder 12 (copper powder aggregate 13) must: (1) have fine particles and less coarse particles;

■ Good liquidity.

■ Good dispersibility and no agglomeration.

is required.

[Conventional technology]

FIG. 8 shows a conventional method for producing a copper powder aggregate.

The copper powder aggregate is processed through wet kneading process 20. It is manufactured through a solvent removal step 21 and a surface modification step 22.

In the wet kneading step 20, as shown in FIG. 9, an aggregate 33 of copper powder 32 as a raw material and a titanium coupling agent 34 are placed in a tank 31 containing methyl ethyl ketone 30 as a solvent, and are stirred. This is carried out by kneading using a screwdriver.

The particle size distribution of the copper powder aggregate 33 is as shown by the linework in FIG. 5, and the particle size is concentrated near about 3 μm.

The titanium coupling agent 34 is an organometallic compound of titanium, and is in the form of starch syrup.

The reason why this titanium coupling agent 34 is kneaded is that when the green sheet laminate is fired, titanium becomes titanium oxide, which causes the copper powder 32 to bond with each other and the copper powder 32 to the inner peripheral wall surface (ceramic) of the pie hole 10. This is to increase the strength of the bond.

By the above wet kneading, a kneaded body 36 shown in Fig. 1θ is obtained.

In the solvent removal step 21, as shown by the arrow 37 in FIG.
The gas evaporated from the methyl ethyl ketone 30 is exhausted, and a solvent-removed kneaded body 38 is shown.

This desolventized kneaded body 38 is in the form of a lump that can be crushed relatively easily, and as shown by reference numerals 40 and 41 in FIG. In addition to the one encapsulated with the titanium coupling agent 34a, the symbol 42
As shown in , agglomerated copper powder 43 where a plurality of copper powders 32 aggregate
It contains a large amount of titanium coupling agent 34a that is encapsulated with dry titanium coupling agent 34a.

This aggregation is due to the titanium coupling agent 34, and there is also aggregation of several dozen copper powders.

Therefore, the particle size distribution of the solvent-removed kneaded body 38 is
It becomes as shown.

If left as is, the particle size is large and the surface is angular, resulting in poor fluidity and a tendency to aggregate, so the surface is modified.

The surface modification step 22 is performed using a high-speed air collision device 50 shown in FIG.

This device 50 is a device that applies a high-speed airflow collision method, and the blades 52 or 10,000 to 1
It is configured to rotate at a high speed of 5,000 rpm.

The desolventized kneaded body 38 is passed through the pipe 53 to the blade 52
is fed to the center of the plane, flies and collides as shown by the dashed line,
It is repeatedly circulated through the circulation circuit 54.

In this process of flying and circulating while colliding with each other, the copper powder has its edges removed, and the agglomerated copper powder is decomposed and further removed, thereby modifying its surface.

The surface-modified copper powder aggregate 60 is taken out through the discharge valve 55 and the chute 56.

FIG. 14 shows the structure of this surface-modified copper powder aggregate 60.

6I is a surface-modified copper powder made of - copper powder 32, and the surface has been modified to have a rounded state.

62 is a surface-modified copper powder in which two copper powders 32 are aggregated;
63 is a surface-modified copper powder in which three copper powders 32 are aggregated.

Conventionally, this surface-modified copper powder aggregate 60 was used to
A via 9 was formed as shown in the figure.

Since each powder of this surface-modified copper powder aggregate 60 is a spherical body with a rounded surface, it has good fluidity and dispersibility, and filling into the via hole 10 is performed smoothly to a certain extent. .

[Problem to be solved by the invention]

The desolventized kneaded body 38 subjected to surface modification contains a relatively large amount of a plurality of aggregated copper powders, as shown by the line (■) in FIGS. 12 and 5.

Therefore, even after the surface modification, a considerable amount of agglomerated copper powder remains, and the particle size distribution of the copper powder becomes as shown by the line (2) in FIG.

Therefore, in some cases, the via hole may be filled with particles having a large diameter, and in such a case, there is a possibility that the via hole may not be filled completely and voids may occur.

An object of the present invention is to provide a method for manufacturing a metal powder aggregate for filling via holes, which enables finer particle size reduction.

[Means to solve the problem]

The present invention comprises a wet kneading process for kneading an aggregate of metal powder with an organometallic compound in a solvent to obtain a kneaded body, and a desolvation process for removing the solvent from the kneaded body to obtain a desolvated kneaded body. , a crushing step of crushing the solvent-removed kneaded body to obtain a crushed powder aggregate in which the metal powder is encapsulated by the organometallic compound; and the surface of each powder in the crushed powder aggregate. The structure consists of a surface modification step in which a metal powder aggregate for filling via holes is obtained by modifying the metal powder.

[Effect]

The crushing process eliminates agglomerated metal powder with a large particle size, which is a plurality of metal powders or agglomerated metal powders.

By providing this crushing process before the surface modification process,
Some of the particles are surface-modified in the form of agglomerated metal powders with a large particle size, and most of them are in the state of surface-modified metal powder units.

〔Example〕

FIG. 1 shows a method for producing metal powder for filling via holes according to an embodiment of the present invention.

In the manufacturing method of the present invention, the desolvation step 21 is followed by the crushing step 7.
0, and the crushed material is subjected to surface modification in the next surface modification step 22.

For the crushing step 70, a vibrating mill 80 shown in FIG. 2 is used.

The vibrating mill 80 includes a tank 81 and a vibrator 82 that vibrates the tank 81 at intervals of 3000 times per minute in the vertical direction (X direction) and the horizontal direction (X direction).

The tank 81 consists of an upper seed part 83 and a lower seed part 84, and the bottom of the upper seed part 83 has a roughness of 100 mesh and a diameter of 200 ffl! Eleven filters 85 are provided. In addition, 50 to 200 holes 86 made of zirconium oxide and having a diameter of 5M are placed in the upper seed portion 83.

The wet kneading step 20 and the solvent removal step 21 are performed in the same manner as conventional methods, and their explanation will be omitted.

Next, a crushing step 70 is performed.

The desolventized kneaded body 38 is put into the upper seed part 83 of the vibrating mill 80, and the vibrator 82 is vibrated at predetermined intervals without stopping.

As a result, the tank 81 is vibrated vertically and horizontally, and the agglomerates are broken up by the impact and friction of the balls 86.

As mentioned above, the number of balls 86 is as large as 50 to 200,
The crushing is efficient and thorough, resulting in a large amount or one unit of copper powder.

The filter 85 vibrates together with the tank 81 and functions as a "sieve".

As a result, whether the particles have been crushed to a size smaller than 100 meshes or have passed through the filter 85 and the lower seed part 8
It accumulates to 4.

What accumulates in the lower seed portion 84, ie, the crushed copper powder aggregate 90, is schematically shown in FIG. 3.

That is, in many cases, one unit of copper powder 32 as shown by reference numeral 91 is used.
It is coated with the dried titanium coupling agent 34a, and as shown by reference numeral 92, there are few agglomerated particles of a plurality of copper powders 32, and moreover, when looking at the agglomerated particles, it is found that the agglomerated copper powder There are few.

The grain roughness distribution of this crushed copper powder aggregate 90 is as shown by the line 2 in FIG. 5, with no agglomerated grains having a grain size of several tens of μm or more.

This crushed copper powder aggregate 90 is transferred to a surface modification step 22,
The surface is modified to make it spherical in the same manner as above.

Some agglomerated particles are also broken up during the surface modification process.

As a result, as shown in FIG. 4, most of the copper powder aggregates 100 obtained by the surface modification method have -
The unit copper powder 32 is coated with a titanium coupling agent 34a, and as shown by the reference numeral 102, there are few agglomerated powders of a plurality of copper powders or agglomerated powders. The number of copper powders present is small, 2 to 3 pieces.

Therefore, the particle size distribution of the surface-modified copper powder aggregate 100 becomes as shown by the line (■) in FIG. 5, which approximates the particle size distribution (line -) of the original copper powder aggregate 33.

As a result, a surface-modified copper powder aggregate 100 having excellent fluidity and dispersibility and having a finer particle size than the conventional method can be obtained.

By using this surface-modified copper powder aggregate 100, the copper powders 101 and 102 can easily enter the via hole 10 without being caught in the middle, and completely fill the via hole 10. As a result, high-quality vias without voids can be stably formed, and finally ceramic printed wiring boards can be manufactured with a high yield.

Note that for the above-mentioned crushing, a pole 86 made of zirconium oxide is used as a pole. This is because the balls 86 have high hardness and do not generate shavings even when the balls 86 collide with each other, that is, to prevent powder of a material other than the copper powder 100 from being filled into the pie hole.

Furthermore, the present invention can be applied to the production of silver powder, gold powder, palladium powder, etc. in addition to copper powder.

〔Effect of the invention〕

As explained above, according to the present invention, there is no agglomerated metal powder with a large particle size, and most of the metal powder is surface-modified in the state of unitary metal powder, so that it can be filled well into the pipe hole. metal powder aggregates can be produced.

Further, by forming vias using the metal powder aggregate manufactured by the manufacturing method of the present invention, it is possible to eliminate the generation of voids, and it is possible to improve the yield of ceramic printed wiring boards.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the method for producing a metal powder aggregate for filling via holes according to the present invention, Fig. 2 is a diagram showing an apparatus for carrying out the crushing process, and Fig. 3 is a diagram showing a crushed copper powder aggregate. Figure 4 is a diagram showing the structure of surface-modified copper powder aggregates, Figure 5 is a diagram showing the particle size distribution of surface-modified powder aggregates, etc., Figure 6 is ceramic print. Figure 7 is a diagram showing the general manufacturing process of wiring boards, Figure 7 is a diagram explaining the formation of vias, Figure 8 is a diagram showing the conventional manufacturing method of copper powder aggregate, and Figure 9 is a diagram explaining wet kneading. Figure 10 is a diagram showing the state after wet kneading, Figure 11 is a diagram showing the state after the solvent removal process, Figure 12 is a diagram schematically showing the structure of the solvent-removed kneaded body, and Figure 13 is a diagram showing the state after the wet kneading process. FIG. 14 is a diagram showing a high-speed air collision apparatus for surface modification. FIG. 14 is a diagram showing the structure of a surface-modified copper powder aggregate. In the figure, is the via formation process, is the via, 0 is the via hole, 1 is the green sheet, 3 is the aggregate of surface-modified copper powder, 0 is the wet kneading process, l is the solvent removal process, and 2 is the surface modification process. , 0 is methyl ethyl ketone (solvent), 1 is a tank, 2 is copper powder, 3 is copper powder aggregate, 4 is a titanium coupling agent (organometallic compound), 4a is a dried titanium coupling agent, 6 is a kneaded body, 7 is an arrow indicating exhaust, 8 is a desolventized kneaded body, 0 is a high-speed air collision device, 0 is a crushing process, 80 is a vibration mill, 81 is a tank, 82 is a vibrator, 83 is an upper seed section, 84 is Lower seed part, 85 is a filter, 86 is a ball made of zirconium oxide, 90 is a crushed copper powder aggregate, 91.92 is a crushed copper powder, 100 is a surface-modified copper powder aggregate, 101 is a Surface-modified copper powder, 102 indicates surface-modified agglomerated powder. Figure 3: Figure 1 Figure 4 Figure 2 Figure 5 Figure 6 Figure 9 Figure 11 Figure 7 Figure 8 38 Removal of leprosy 1. Depopulation Figure 12 Figure 14

Claims (1)

[Scope of Claims] A wet kneading step (20) of kneading a metal powder aggregate (33) with an organometallic compound (34) in a solvent (30) to obtain a kneaded body (36); 36), a desolvation step (21) to obtain a desolventized kneaded body (38), and a desolvation step (21) to obtain a desolventized kneaded body (38), and a step in which the metal powder is covered with the organometallic compound by crushing the desolventized kneaded body (38). Aggregate of packed crushed powder (90
) and a crushing step (70) to obtain the crushed powder aggregate (9
0) Surface modification step (22) of modifying the surface of each powder to obtain a metal powder assembly (100) for via hole filling. Method.