JPH0964541A - Production of multilayered ceramic wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a ceramic multilayered wiring board excellent in the reliability of connection between the wiring conductor of the outer layer formed by a thin film method and a conductor of via part formed by a thick film method. SOLUTION: The wiring conductor of the outer layer is formed by a thin film method on the surface of a ceramic board where the wiring conductor of the inner layer is formed by a thick film method and integrated. In such a method for producing a ceramic multilayered wiring board, the surface of a ceramic board is roughened using heated phosphoric acid prior to formation of the wiring conductor of the outer layer. In this production method, the temperature of phosphoric acid for roughening the surface of the ceramic board is set in the range of 140-360 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic multilayer wiring board used as an electronic component.

[0002]

2. Description of the Related Art As a method of forming a wiring conductor of an outer layer in a conventional ceramic multilayer wiring board, a thick film method of printing and firing a conductor paste is generally used as in the method of forming an internal wiring conductor. However, in the case of the thick film method, it is difficult to form a fine circuit, and since the glass frit is contained as a constituent component, there is a problem in solderability. Therefore, a method of forming a wiring conductor of an outer layer by a thin film method such as vapor deposition, sputtering or plating has been studied, and is disclosed in, for example, Japanese Patent Laid-Open No. 6-104569. With this method, a fine circuit can be formed, and the problem of solderability can be solved. However, when the outer layer wiring conductor is formed by the thin film method, there is a problem in connection reliability between the outer layer wiring conductor and the conductor formed by the thick film method forming the via portion (a part of the inner wiring). At present, the improvement is required.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is a method of forming a wiring conductor of an outer layer by a thin film method. (EN) A ceramic multilayer wiring board manufacturing method capable of manufacturing a ceramic multilayer wiring board excellent in connection reliability between a wiring conductor of (1) and a conductor forming a via portion by a thick film method.

[0004]

According to a first aspect of the present invention, there is provided a ceramic multilayer wiring board manufacturing method, wherein an inner wiring conductor is formed by a thick film method and integrated on a surface of a ceramic substrate to form an outer layer by a thin film method. In the method for manufacturing a ceramic multilayer wiring board for forming a wiring conductor, the surface of the ceramic substrate is roughened with hot phosphoric acid before the wiring conductor of the outer layer is formed.

The method for manufacturing a ceramic multilayer wiring board according to a second aspect of the present invention is the method according to the first aspect, wherein the temperature of the heated phosphoric acid for roughening the surface of the ceramic substrate is 140 to 360 ° C. It is characterized by

[0006]

Embodiments of the present invention will be described below.

In the present invention, a ceramic substrate is used in which internal wiring conductors are formed by a thick film method and integrated. The thick film method here is a method of printing and firing a conductor paste to form a wiring conductor, and as the conductor paste, a tungsten paste, a silver paste, a copper paste, or the like can be used. Further, as a method of obtaining an integrated ceramic substrate, for example, a method of integration using a glass ceramic green sheet such as cordierite, a method of integration using a high temperature firing type ceramic green sheet such as alumina, or A thick film printing multilayer method using a paste which becomes a ceramic insulating film by firing (Japanese Patent Laid-Open No. 6-104)
No. 569) and the like, and there is no particular limitation.

In the present invention, before forming the outer layer wiring conductor on the surface of the above-mentioned integrated ceramic substrate by the thin film method,
The surface of this ceramic substrate is roughened by using hot phosphoric acid. At that time, a via portion, which is a part of the internal wiring formed by the thick film method, is exposed on the surface of the ceramic substrate, and the via portion is also roughened by hot phosphoric acid. Therefore, when the outer layer wiring conductor is formed by the thin film method after the roughening treatment, the outer layer wiring conductor and the thick film method conductor forming the via portion are firmly connected by the anchor effect. Therefore, a ceramic multilayer wiring board having excellent connection reliability can be obtained. Note that it is not preferable to perform the surface roughening treatment using hydrofluoric acid, because if hydrofluoric acid remains on the substrate surface, the etching may gradually progress and the metal film formed by the thin film method may be corroded.

The conditions for the surface roughening treatment with the heated phosphoric acid of the present invention are not particularly limited, but the temperature of the heated phosphoric acid is preferably 140 to 360 ° C. 1
When the temperature is lower than 40 ° C., the surface roughening is insufficient, and when the temperature is higher than 360 ° C., the surface roughening becomes excessive and the substrate strength tends to be lowered.

[0010]

The present invention will be described below based on examples and comparative examples.

(Example) A via hole for interlayer connection was punched out in a green sheet mainly composed of lead borosilicate glass and alumina powder, and an inner circuit pattern was printed and a via hole was formed by using a silver paste containing glass frit. The inside was filled with paste. (However, the circuit pattern was not printed on the green sheet used for the uppermost layer, and only the paste was filled in the via holes.) Then, three green sheets were laminated and pressed,
By firing in an oxidizing atmosphere at 900 ° C., an integrated ceramic substrate was obtained. 180 thus obtained ceramic substrate
The surface of the via portion and the surface of the ceramic substrate made of a conductor obtained by firing a silver paste was roughened by immersing in hot phosphoric acid at ℃ for 5 minutes. After that, after performing a nucleating treatment on the surface of the ceramic substrate, the ceramic substrate is immersed in an electroless copper plating solution to form a copper plating layer having a film thickness of 10 μm.
An etching resist was applied on the copper plating layer, and an outer layer circuit was formed by an etching method to obtain a ceramic multilayer wiring board having a four-layer structure (two layers of inner layer circuit and two layers of outer layer circuit). The ceramic multilayer wiring board was manufactured so as to have a conduction circuit in which the outer layer circuit and the inner layer circuit were connected via 256 via portions.

(Comparative Example) A ceramic was prepared in the same manner as in the previous example except that the ceramic substrate integrated by firing was not subjected to surface roughening treatment with hot phosphoric acid. A multilayer wiring board was obtained.

The ceramic multilayer wiring boards obtained in Examples and Comparative Examples were tested for connection reliability by the following method. The results obtained are shown in Table 1. From the results in Table 1, it was confirmed that the ceramic multilayer wiring board of the example had better connection reliability than the ceramic multilayer wiring board of the comparative example.

(Test method for connection reliability) For a ceramic multilayer wiring board, [(room temperature, 5 minutes) → (125 ° C., 30
Min) → (room temperature, 5 minutes) → (−55 ° C., 30 minutes) → (room temperature)] as one cycle,
After completing the predetermined number of cycles, the electrical resistance between both ends of the conductive circuit in which the outer layer circuit and the inner layer circuit are connected via 256 via portions is measured by the four-terminal method,
Calculate the rate of resistance change. The relationship between the number of cycles applied and the resistance change rate is tabulated and the connection reliability is evaluated. In addition,
The one with a small resistance change rate has a good connection reliability.

[0015]

[Table 1]

[0016]

According to the method for manufacturing a ceramic multilayer wiring board of the present invention as defined in claims 1 and 2, a method for forming an outer layer wiring conductor by a thin film method is provided, in which the outer layer wiring conductor and the via portion are formed. It is possible to manufacture a ceramic multilayer wiring board having excellent connection reliability with the conductor by the formed thick film method.

Claims (2)

[Claims] 1. A method for manufacturing a ceramic multilayer wiring board, wherein an inner wiring conductor is formed by a thick film method to form an integrated ceramic substrate, and an outer wiring conductor is formed on the surface of the ceramic substrate by a thin film method.
A method for manufacturing a ceramic multilayer wiring board, characterized in that the surface of the ceramic substrate is roughened with hot phosphoric acid before forming the outer layer wiring conductor. 2. The method for producing a ceramic multilayer wiring board according to claim 1, wherein the temperature of the heated phosphoric acid for roughening the surface of the ceramic substrate is 140 to 360 ° C.