JPH06216525A - Manufacture of multi layer printed circuit board - Google Patents

Abstract

PURPOSE:To improve packing density, by covering an insulating board including a wiring pattern and a circuit element with a photosensitive polymeric insulating film, and forming an interlayer conductor in a longitudinal hole after the longitudinal hole is formed in the photosensitive insulating film in an exposure- development step. CONSTITUTION:An alumina board 2 having a base wiring pattern 3 and a resistor 4 thereon is coated with photosensitive polyimide to form a first photosensitive polyimide film 5. A viahole 6 is formed in the first photosensitive polyimide film 5 in an exposure-development step. After the first photosensitive polyimide film 5 is hardened in a thermo-setting step, a first copper plated circuit 7 and an intermediate wiring pattern 8 are formed on the first photosensitive polyimide film 5. Then, a second photosensitive polyimide film 9 is formed over the first photosensitive polyimide film 5. Finally, a necessary electronic component other than the resistor 4 is mounted on the second photosensitive polyimide film 9.

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 multilayer wiring board used as a mounting board for electronic parts such as LSI.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a multilayer wiring board, wiring patterns are formed on both sides of an insulating substrate by screen printing or the like, and then through holes are formed in the insulating substrate to connect the wiring patterns on both sides to each other. There is a way. In addition, as disclosed in Japanese Patent Laid-Open No. 61-294895, a low dielectric constant polymer film (for example, a polyimide film) is used as an interlayer insulating film on an insulating substrate on which a wiring pattern is formed.
There is also a method of forming a single layer or a plurality of layers and forming an interlayer wiring in these polymer films to form a multilayer.

[0003]

However, the above-mentioned conventional method has the following problems. That is, according to the first method of manufacturing both surfaces of the insulating substrate with the through holes, since only the both surfaces of one insulating substrate are connected with the through holes, high-density mounting cannot be realized. Also, the second method using a polymer film enables high-density mounting and multi-layering, but the pattern of interlayer wiring and the like becomes complicated, and electronic parts such as LSI, resistors, and capacitors are polymer films. Since it can only be mounted on the surface, there was a limit to high-density mounting in that sense.

Therefore, an object of the present invention is to increase the packaging density of the multilayer wiring board.

[0005]

In order to achieve such an object, in the present invention, a step of printing a wiring pattern and a circuit element on an insulating substrate, and an insulating substrate on which the wiring pattern and the circuit element are formed. A step of forming a photosensitive polymer insulating film thereon, and forming a vertical hole for interlayer connection in the photosensitive polymer insulating film by an exposure and development process, and forming the wiring pattern in the vertical hole with the photosensitive polymer insulating film. A method of manufacturing a multilayer wiring board is configured including a step of forming an interlayer wiring leading to the surface.

[0006]

According to the above structure, the circuit density such as a resistor can be disposed between the insulating substrate and the photosensitive polymer insulating film, so that the mounting density is increased.

Further, since a part of the circuit elements can be arranged between the layers, the wiring pattern connecting these circuit elements can be simplified.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view showing a structure of a multilayer wiring board manufactured by a method for manufacturing a multilayer wiring board according to the present invention, and FIG. 2 is a sectional view showing a manufacturing process of the multilayer wiring board.

This multilayer wiring board 1 has a high purity (for example, 9
9.5%) of the alumina substrate 2. On the surface of the alumina substrate 2, a base wiring pattern 3 made of Ag-Pd and RuO ₂ connected to the base arrangement pattern 3 are formed.
A resistor 4 consisting of is provided. A first photosensitive polyimide film 5, which is a photosensitive polymer insulating film, is provided on the surface of the alumina substrate 2. A via hole 6 is formed in the first photosensitive polyimide film 5 in the thickness direction, and a first copper-plated wiring 7 is provided in the via hole 6. First
The copper-plated wiring 7 extends to the surface of the first photosensitive polyimide film 5 to form an intermediate wiring pattern 8. The first copper-plated wiring 7 is connected to the base wiring pattern 3,
As a result, the base wiring pattern 3 is led out to the surface of the first photosensitive polyimide film 5.

A second photosensitive polyimide film 9 is further provided on the surface of the first photosensitive polyimide film 5. A via hole 10 is formed in the second photosensitive polyimide film 9 in the thickness direction, and a second copper plated wiring 11 is provided in the via hole 10. The second copper-plated wiring 11 extends to the surface of the second photosensitive polyimide film 9 to form a surface layer wiring pattern 12. The second copper-plated wiring 11 is connected to the intermediate wiring pattern 8 so that the intermediate wiring pattern 8 is extended to the surface of the second photosensitive polyimide film 9. Then, the second photosensitive polyimide film 9
Electronic components (LSI, capacitors, etc.) other than the resistor 4 are mounted on the surface wiring pattern 12 on the surface.

Next, the manufacturing process of the multilayer wiring board 1 having the above structure will be described step by step. First, Ag-
The Pd wiring pattern raw material is patterned by screen printing and then baked at 850 ° C. to form the base wiring pattern 3. Further, RuO ₂ , which is a resistance material, is patterned on the alumina substrate 2 by screen printing and then baked at 850 ° C. to form the resistance 4. In this way, the resistor 4 is formed before forming the photosensitive polyimide films 5 and 9 that cannot be subjected to the high-temperature heat treatment, so that the resistor 4 can be formed on the alumina substrate 2 without any problem. See FIG. 2A. A photosensitive polyimide resin (for example, Photo Nice: trade name, manufactured by Toray Industries, Inc.) is applied on the alumina substrate 2 on which the base wiring pattern 3 and the resistor 4 are formed to form the first photosensitive polyimide film 5. Form. Figure 2 (b)
Reference Further, the first photosensitive polyimide film 5 is subjected to an exposure and development process to form a via hole 6, and then the first photosensitive polyimide film 5 is cured by heating. Referring to FIG. 2C, the first copper-plated wiring 7 and the intermediate wiring pattern 8 are formed on the first photosensitive polyimide film 5 thus formed by the semi-additive method. That is, the first photosensitive polyimide film 5 is subjected to a surface treatment with hydrazine and further subjected to a catalyst activation treatment with palladium. After such treatment, the alumina substrate 2 is dipped in a copper sulfate plating solution to expose the base wiring pattern exposed on the surface of the first photosensitive polyimide film 5 and the bottom of the via hole 10. An electroless copper plating layer 20 having a film thickness of 500 angstrom is formed on the substrate 8. A photoresist (for example, AZ4620 manufactured by Hoechst: trade name) is applied on the electroless copper-plated layer 20 thus formed, and the photoresist is subjected to an exposure and development process to form a resist pattern 21. Then, electrolytic copper plating is applied to the portion of the electroless plating layer 20 exposed from the resist pattern 21 to form a 5 μm electrolytic copper plating layer 22. Then, the resist pattern 21 and the electroless copper-plated layer 20 located under the resist pattern 21 are removed to form the first copper-plated wiring 7 and the intermediate wiring pattern 8. Figure 2 (e)
Further, a second photosensitive polyimide film 9 is formed on the first photosensitive polyimide film 5, and the second photosensitive polyimide film 9 is formed.
Then, the same steps as those for the first photosensitive polyimide film 5 described above are performed to form the via holes 10, the second copper plated wirings 11, and the surface layer wiring patterns 12.
See FIG. 2 (f) Finally, on the surface layer wiring pattern 12 of the second photosensitive polyimide film 9, electronic components (LS) other than the resistor 4 described above are required.
I, capacitors, etc.) are surface-mounted, and the multilayer wiring board 1 shown in FIG. 1 is completed by this.

The applicant of the present invention prepared the following as a comparative product in order to investigate to what extent the high density of mounting was promoted by the manufacturing method of such a multilayer wiring board, and When the mounting degree was compared with that of the product, it was found that the mounting strength of the example product was about 1.35 times that of the comparative product. The comparative product is the same as the embodiment product in that two layers of a photosensitive polyimide film having a via hole are laminated on an alumina substrate, and constituent elements other than the resistance, that is, a base portion, an intermediate portion, and a surface layer portion are formed. Each wiring pattern, first,
The second copper-plated wiring is formed, and further, all electronic components including resistors are surface-mounted on the surface of the second photosensitive polyimide film. The mountability was calculated as the minimum plane area of the substrate required to form a predetermined circuit configuration.

[0013]

As described above, according to the present invention, it becomes possible to arrange a circuit element such as a resistor between layers of a multilayer wiring board including an insulating substrate and a photosensitive polymer insulating film. Therefore, high density packaging was achieved.

Further, since a part of the circuit elements can be arranged between the layers of the multilayer wiring board, it is possible to simplify the wiring pattern for connecting these circuit elements, and the mounting density is further increased by that amount. Became possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of a multilayer wiring board manufactured by a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing each step of the method for manufacturing a multilayer wiring board according to an embodiment of the present invention.

[Explanation of symbols]

 2 Alumina substrate 3 Base wiring pattern 4 Resistor 5 First photosensitive polyimide film 6 Via hole 7 First copper plated wiring 8 Intermediate wiring pattern

Claims (1)

[Claims] 1. A step of printing a wiring pattern and a circuit element on an insulating substrate, a step of forming a photosensitive polymer insulating film on the insulating substrate on which the wiring pattern and the circuit element are formed, and the photosensitive polymer. Forming a vertical hole for interlayer connection in the insulating film by an exposure and development process, and forming an interlayer wiring for leading the wiring pattern to the surface of the photosensitive polymer insulating film in the vertical hole. Wiring board manufacturing method.