JPH08222852A - Manufacture of through hole filled up with conductor - Google Patents

Abstract

PURPOSE: To firmly stick a conductor to a ceramic substrate by filling up the through hole of the ceramic substrate with conductor paste having a low shrink characteristic after a glass layer is formed on the internal surface of the through hole by printing and baking glass paste and baking the conductor paste. CONSTITUTION: A glass layer or conductor layer 3 containing a glass component is formed on the internal surface 2a of the through hole 1 of a ceramic substrate 1 by printing and baking paste to improve the adhesion of the internal surface 2a of the hole 2 and a conductor filling up the hole 2. Then a filled-up through hole is obtained by filling the hole 2 with the glass layer or conductor layer 3 containing the glass component on its internal surface 2a with conductor paste 4 having a low shrink property and baking the paste 4. The conductor used for filling up the hole 2 is prepared by mixing >=0.1wt.% ruthenium oxide powder or rhodium powder in conductive powder composed mainly of silver or copper powder. When the paste 4 is used, the reliability of the connection between the wiring on the surface of the substrate 1 and through hole conductor can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a conductor-filled through hole. More specifically, when forming a thick film circuit of silver, silver / palladium, copper, etc. on a ceramic substrate for electronic component circuits, which is typified by alumina, a conductor-filled through formed to establish continuity of the circuits on both sides of the substrate. The present invention relates to a hall manufacturing method.

[0002]

[Description of Related Art] As a method of forming wiring (circuit) on a ceramic substrate, a thick film circuit method of printing and firing a conductive material powder paste (conductor paste) containing silver, copper or the like as a main component is used. There is. A general ceramic circuit board is, for example, a 96% alumina ceramic, which is mainly composed of metal powder such as silver, silver / palladium, and copper, and is mixed with a certain amount of a vehicle. It is formed by baking at about 800 to 900 ° C. and baking on a substrate. It is also a common method to provide circuits on both sides of the substrate in order to improve the circuit density. In this case, the circuit between the two-sided circuits is provided with through holes in the substrate, printed with a conductive paste, and then baked. This is done by baking a conductor on the wall surface of the hole. Here, the printing of the conductive paste is performed by a method of causing the paste to wrap around the wall surface of the through hole by using a normal screen printing technique while sucking from below the substrate.

The reason why the conductor is formed on the wall surface of the through hole is that the conductive paste used so far has a problem of shrinkage in the firing process. When the through hole is filled with the conductor paste and fired, the firing shrinkage force is ceramic. This is because there is a drawback that the formed conductor exceeds the adhesive force to the substrate and the formed conductor is peeled off from the ceramic substrate. Therefore, a method of printing and firing a conductor film on the wall surface of the through hole by a screen printing method or the like to interconnect the wiring on the substrate has been implemented. However, in such a method, the film thickness at the corner portion from the through-hole wall to the circuit on the substrate surface is likely to be thin, and when a high current is applied, the corner portion generates heat and causes conduction failure. Therefore, there is a problem that it is not suitable for high output products. In addition, the size of the through hole is conventionally 0.4 mm in diameter (φ) because of the wiring density.
Since the degree is standard and the amount of conductor formed on the wall surface of the hole is limited, there is a problem that the conductor resistance in the through hole portion becomes large.

In recent years, electronic devices have become smaller and higher in performance, and highly reliable multilayer wiring ceramic substrates capable of high-density mounting of electronic components have been demanded. The printing multilayer method for manufacturing multilayer wiring substrates is required. Alternatively, the green sheet multilayer method also has a problem in interlayer connection by through holes.
That is, in the printing multi-layer method, since the paste enters the through holes when the insulating layer is printed, a reliable insulating layer cannot be formed on the through holes, and it is necessary to print the wiring while avoiding the holes of the through holes. It hinders high density. In the case of the green sheet multi-layer method in which a green sheet made of glass ceramic is laminated on a ceramic substrate and is fired to form a high-density wiring between sheets, the through holes are hollow, so The green sheet (glass ceramic) is sunk into the through hole to cause a crack in the periphery, and the wiring provided on the surface of the sheet is broken.

Therefore, the present applicant previously proposed a conductor paste for filling through-holes, which has a significantly lower firing shrinkage than the conventional one and is excellent in shape stability before and after firing (Japanese Patent Application No. No. 167439, Japanese Patent Application No. 6-51306). By using this conductor paste, the reliability of the connection between the wiring on the substrate and the through-hole conductor is improved, and since a large amount can be filled in the through-hole, the conventional method of metalizing only the wall surface of the through-hole by screen printing is used. Conductor resistance is lower than that of the above, and defects such as cracks due to penetration of the insulating layer paste into the through holes and sinking of the green sheet do not occur, and there is no inconvenience such as short circuit or disconnection. It has the advantage that it can be built on a substrate.

When a conductor having a low shrinkage ratio is filled in a through hole of a ceramic substrate, a diameter larger than that of the through hole is used for work efficiency, for example, a pad diameter of φ = 0.6 mm for a through hole of φ = 0.4 mm. Need to print,
When manufacturing a circuit board, it is necessary to remove extra conductors. Further, since the low-shrinkage conductor does not contain a bonding component with a ceramic such as glass, if it remains on the surface of the ceramic, the adhesive strength is lowered.

Therefore, when the method of filling the through-hole with the above-mentioned low-contraction filling conductor paste, which the applicant of the present invention has previously proposed, was examined, the conductivity by the through-hole between the thin film conductor wirings was improved. However, it has been found that there is a problem in the adhesive force between the filling conductor and the wall surface of the through hole, and the filling conductor may be chipped or the filling conductor may come off from the through hole during the lapping process.

[0008]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to prevent the filling conductor from being chipped or passing through during the planarization process required in the step of forming a circuit in the substrate in which the through holes are filled in the ceramic substrate. It is an object of the present invention to provide a method of manufacturing a conductor-filled through hole with improved adhesion, which does not come off from the hole.

[0009]

Means for Solving the Problems As a result of intensive studies made by the present inventors on the adhesiveness between a ceramic substrate and a conductor paste, a glass layer or a conductor layer containing a glass component is formed on the wall surface of the through hole before filling the through hole with the conductor paste. After the formation, the conductive paste was filled and fired, and it was confirmed that the ceramic substrate and the conductor were firmly bonded, and the present invention was completed.

[0010]

DISCLOSURE OF THE INVENTION That is, the present invention is characterized in that (1) a glass paste is printed and fired on a wall surface of a through hole of a ceramic substrate to form a glass layer, and then a low-shrinkage filling conductor paste is filled and fired. And (2) a glass paste containing a conductive material powder is printed and fired on the wall surface of the through hole of the ceramic substrate to form a glass component-containing conductor layer, and then a low shrinkage filling conductor. A method for manufacturing a conductor-filled through hole, which comprises filling and firing a paste, and (3) a low-shrinkage conductor paste for filling, wherein ruthenium oxide powder or ruthenium oxide powder is added to a conductive material powder containing silver powder or copper powder as a main component. 3. A method for manufacturing a conductor-filled through hole according to 1 or 2 above, which is a mixed powder paste containing 0.1% by weight or more of rhodium powder. That.

A method of manufacturing a conductor-filled through hole according to the present invention will be described below with reference to FIGS. In the method of the present invention, the glass layer or the conductor layer containing the glass component is formed on the wall surface 2a of the through hole 2 of the ceramic substrate 1 by using a raw material paste and a general thick film printing method.

The raw material paste for forming the glass layer is glass powder to which a vehicle is added and kneaded. The raw material paste for forming the conductor layer containing a glass component is composed of glass powder and conductor powder. This is a mixture of powder and vehicle mixed and kneaded. The average particle size of the glass powder is preferably about 1 to 6 μm. Here, as the glass component, PbO, B ₂ O ₃ , ZnO, CaO, SiO ₂ , A
It may consist of general glass components such as l ₂ O ₃ ,
It has a glass softening point (Ts) of 500 to 1000 ° C, preferably 600 to 900 ° C. Glass softening point is 50
If the temperature is lower than 0 ° C, the viscosity of the glass for joining will be too low during firing of the filling conductor, and the amount of transfer to the filling conductor side will increase, which will not contribute to the joining of the filling conductor and the wall surface of the through-hole, but also for filling. This increases contraction of the conductor and causes the filling conductor to peel off from the through hole. Further, when the glass softening point exceeds 1000 ° C., the glass does not soften favorably by the heat when firing the filling conductor paste, and the adhesiveness is affected.

As the conductor material powder, one containing metal powder such as silver powder or copper powder as a main component is used. The conductive material powder preferably has an average particle size of about 1 to 6 μm, which is the same as that generally used as a paste for thick film printing. Can be used. Further, as the paste material, a commercially available conductor paste prepared for a ceramic substrate, for example, a conductor paste of silver, silver / platinum, silver / palladium, copper or the like can be used.

The vehicle added to the glass powder consists of a binder and a solvent. Ethyl cellulose as a binder,
Acrylic resin or the like is used, and as the solvent, ethyl carbitol acetate, terpineol, or the like is used. The amount of the binder used may be such an amount that the glass powder is uniformly dispersed and held, and the paste state can be maintained.
The amount of the solvent used varies depending on the kind of the binder, but may be any amount as long as it imparts an appropriate viscosity to the paste. Specifically, it is 10 as a vehicle with respect to 100 parts by weight of the above powder.
About 45 parts by weight are used.

As the paste material, in addition to the above-mentioned components, fatty acid ester or the like can be added in the same manner as known pastes for the purpose of imparting appropriate fluidity. The raw material paste thus prepared is printed on a wall surface of a through hole (φ = 0.15 to 0.6 mm) and fired by a general thick film technique to form a glass layer or a glass component-containing conductor layer 3. Specifically, it is formed by printing the raw material paste on the through hole wall surface 2a by screen printing while sucking from below the substrate, and then firing at 800 to 900 ° C. The film thickness of the glass layer or the glass component-containing conductor layer is preferably as thin as possible so as not to deteriorate the electrical characteristics of the conductor filled in the subsequent step,
For example, it is preferably 20 μm or less, more preferably 10 μm or less.

The through-hole in which the glass layer or the glass component-containing conductor layer is formed is filled with the low-shrinking conductor paste 4 and fired to obtain a filled through-hole (FIG. 1 (c)).
Here, the low-shrinkage conductor paste is not particularly limited as long as it is a conductor paste having a small shrinkage rate during firing, but as a specific example, for the through-hole filling developed by the applicant of the present invention. Conductor (Japanese Patent Application No. 5-167439, Japanese Patent Application No. 6-
No. 51306), that is, a mixed powder obtained by adding a ruthenium oxide powder or a rhodium powder to a conductive powder containing silver powder or copper powder as a main component and kneading the vehicle, and the like can be used.

As the shape of the raw material powder for the conductor paste, for example, any shape such as spherical, lumpy, and scaly can be used. The average particle size of the conductive powder can be about 5 to 10 μm, and the average particle size of ruthenium oxide powder or rhodium powder can be about 0.5 to 2 μm. The amount of ruthenium oxide powder or rhodium powder added is suitably 0.1% by weight or more with respect to the conductive powder from the viewpoint of reducing the heat shrinkage ratio, and 0.1 to 15% by weight for ruthenium oxide powder.
However, in the case of rhodium powder, 0.1 to 3% by weight is preferable. Even if the blending amount of these powders exceeds the above range, there is no change in the effect of reducing the heat shrinkage ratio, which is not economically preferable, and the ratio of the conductive powder is relatively decreased and the electric resistance of the conductor is increased. As the vehicle, the same one as described above for the glass paste or the glass component-containing conductive material paste is used. The mixing ratio of the mixed powder and the vehicle is 10 to 45 parts by weight of the vehicle in which about 5 to 30 parts by weight of the binder is previously dissolved in 100 parts by weight of the solvent based on 100 parts by weight of the mixed powder.

The filling of the conductor paste into the through holes formed with the glass layer or the glass component-containing conductor layer is carried out by a conventional thick film method such as a screen printing method. Then, by firing at a temperature of, for example, 800 to 900 ° C., a filled through hole in which the conductor is firmly adhered to the wall surface of the through hole is produced. The filled through-hole produced by the method of the present invention is then subjected to, for example, surface treatment (lapping or smoothing treatment), and then the conductor pattern 5 is formed by an ordinary method to produce a ceramic wiring board (FIG. 1 (d). ) And (e)).

[0019]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1: Production of a filled through-hole substrate having a glass layer on the wall surface of the through-hole B ₂ O ₃ -ZnO-PbO-based glass powder having an average particle size of 3.5 μm (manufactured by Asahi Glass Co., Ltd.,
ASF-1400) to 100 parts by weight of terpionel 80
A glass paste was prepared by adding 20 parts by weight of a vehicle composed of 20% by weight of ethyl cellulose (binder) and kneading. This glass paste was screen-printed on the wall surface of a through hole of a 96% pure alumina substrate (84.0 mm long × 69.0 mm wide × 0.635 mm thick) having φ = 0.2 mm through holes (600 pieces) and then 800 ° C And baked for 40 minutes to form a glass layer. The thickness of the glass layer is 7 μm
Met. Then, in the through hole of this substrate, a silver powder having an average particle size of 10 μm, a rhodium powder having an average particle size of 1 μm and a vehicle (TRD- manufactured by Tanaka Kikinzoku International Co., Ltd.
After the filling conductor paste prepared from 1) was printed and filled, it was fired at 850 ° C. for 60 minutes to obtain a conductor-filled ceramic substrate. Then, after polishing the surface of this ceramic substrate to a mirror surface and observing the conductor-filled through-holes, no conductor was missing.

Example 2 Production of Filled Through-Hole Substrate with Conductive Layer Containing Glass Component on Wall of Through Hole Commercially available silver / platinum paste (DuPont) containing glass component
A conductor-filled ceramic substrate was produced in the same manner as in Example 1 except that a glass-containing conductor layer having a thickness of 10 μm was formed on the wall surface of the through hole using QS-171, Ag / Pt = 100/1) manufactured by Co. , The surface of the ceramic substrate is mirror-finished,
Observation of the conductor-filled through-holes revealed that none of the conductors were missing.

Comparative Example A filled through-hole substrate was prepared in the same manner as in Example 1 except that the glass layer was not formed, and the surface of the ceramic substrate was mirror-polished in the same manner as in Example 1 to form conductor-filled through-hole portions. As a result of observation, the chipping of the conductor was 65%, and the dropout of the filled conductor was 12%.

[0023]

The present invention is characterized in that a glass layer or a glass component-containing conductor layer is formed on the wall surface of a through hole formed in a ceramic substrate, and then a low-shrinking conductor paste for filling is filled and fired. A method for manufacturing a conductor-filled through hole is provided. The glass layer or the glass-containing conductor layer enhances the adhesiveness between the through-hole wall surface of the ceramic substrate and the filling conductor, so that the filling conductor is not chipped or missing during smoothing processing when manufacturing a thick film circuit or a thin film circuit. Further, in the present invention, since the filling conductor paste having a low firing shrinkage is used, it is excellent in shape stability before and after firing,
By filling this through paste with this conductor paste, the reliability of the connection between the wiring on the substrate surface and the through hole conductor is improved, the amount of conductor in the through hole is increased, and the conductor resistance is increased compared to the conventional type. Since the inside of the through-hole is filled with a conductive paste, the number of layers is reduced, and defects such as cracks do not occur due to the sinking of the green sheet during manufacturing of the green sheet multilayer multilayer wiring. Can be built on a substrate.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a ceramic wiring board manufacturing process according to the method of manufacturing a filled through hole of the present invention.

[Explanation of symbols]

 1 Ceramic Substrate 2 Through Hole 3 Glass Containing Layer 4 Filling Conductor 5 Conductor Pattern

Claims (3)

[Claims] 1. A through hole wall surface of a ceramic substrate,
After forming the glass layer by printing and firing the glass paste,
A method for manufacturing a conductor-filled through hole, which comprises filling a conductor paste for low-shrinkage filling and firing the paste. 2. The through hole wall surface of the ceramic substrate,
A method for producing a conductor-filled through-hole, comprising: printing and firing a glass paste containing a conductive material powder to form a glass component-containing conductor layer, and then filling and firing a low-shrinkage filling conductor paste. 3. The low-shrinkage filling conductor paste is a mixed powder paste prepared by adding 0.1% by weight or more of ruthenium oxide powder or rhodium powder to a conductive material powder containing silver powder or copper powder as a main component. Item 3. A method of manufacturing a conductor-filled through hole according to Item 1 or 2.