JPS5893397A - Manufacturing method of wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for manufacturing a wiring board having four turns of wiring made of a copper thin film. ◎Technical background of the invention and its problems In a conventional thin film wiring board, Cr on an insulating substrate,
Thin films of Pd and Au were sequentially deposited, a photoresist was applied thereon, developed without light, and the thin film was selectively etched away using the photoresist as a mask to form a wiring pattern. Wire (Au)! It is preferable to use it as a pattern material in terms of cost.

On the other hand, when forming a multilayer wiring board using such a thin film wiring pattern, an organic film such as polyimide is conventionally used as an interlayer insulator.

However, since such organic films generally have poor thermal conductivity, there is a problem in reliability when mounting chip components such as high-power LSIs on this multilayer wiring board. Furthermore, when a large current is passed through a wiring pattern, thickening is performed by plating, but the plating process is generally complicated and there is a risk that the pattern may be damaged due to internal stress in the plating film.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for manufacturing a wiring board that is low cost, has no heat dissipation problems, and can withstand large currents.

Summary of the Invention This invention involves forming a copper thin film on a base insulator, coating it with a 7-photoresist, exposing and developing it, and selectively coating the copper thin film using the 7-photoresist as a mask. After removing the photoresist by etching, the photoresist is removed and then baked in a neutral atmosphere at a temperature higher than that at which the copper thin film reacts with the underlying insulator, thereby producing a wiring board having a wiring AI pattern made of the copper thin film. It is characterized by obtaining.

Effects of the Invention According to the present invention, since the thin film wiring layer is formed of a copper thin film, the manufacturing cost can be reduced, and since the layering is performed in one photo etching, a fine wiring pattern can be obtained. Therefore, when forming a multilayer wiring board, a thick film insulator with good thermal conductivity can be used as an interlayer insulator, although it requires firing. As a wiring pattern: 1: Although it requires baking, the process is simpler than plating, and it is possible to use thick film conductors with good electrical conductivity that can withstand large currents. . Therefore, a multilayer wiring board suitable for mounting high-power LSIs and the like can be obtained.

Embodiment of the Invention FIG. 1 is a basic process diagram of an embodiment of the invention. First, a base 1 whose main component is a base insulator such as alumina (At20s) or silicon oxide (sto2)
As shown in FIG. 1(a)K, a thin copper film 2 of about 1 to 20 .mu.m is deposited on the entire upper surface by, for example, vapor deposition, sputtering, plating or the like. Next, as shown in m1 diagram (b) Ic, the copper thin lI
A photoresist 3 is applied on the photoresist 2, exposed to light in a predetermined pattern, and developed to remove unnecessary portions 3. next,
Using the photoresist 3 from which unnecessary portions 3 have been removed as a mask, the thin copper JII 2 is selectively etched away.

Then, the photoresist 3 is removed, for example, by oxygen plasma, or by baking at a temperature that does not oxidize the copper thin film, or by using a resist stripper. After that, the photoresist 3 is removed in a neutral atmosphere, for example, nitrogen. Alternatively, baking is performed in argon at a temperature higher than the temperature at which the copper thin film 2 reacts with the substrate 1, which is an underlying insulator. Here, when the substrate 1 is a material whose main component is Az2O5, a copper aluminate 4 is formed in the temperature range of 900°C to 1200°C as shown in Fig. 1(e)K, and the bond between the copper thin film 2 and the substrate 1 is A strong bond occurs. Also,
If the substrate 1 is made of a material whose main component is 8102, 750
Similar strong bonding occurs in the temperature range from .degree. C. to 950.degree.

In this way, a thin copper film 2 is formed on the substrate J as shown in FIG. 1(c)K.
A parable of a dry wiring pattern Turn 5 is formed. ◎ Fig. 2 shows a process diagram when the present invention is applied to the manufacture of a multilayer wiring board. That is, in order to remove at least a part of the first layer wiring layer 5 made of the copper thin film obtained by the process shown in FIG. By printing and firing the insulating paste as the main component, that is, the insulating paste for thick films that can be fired in a neutral atmosphere,
As shown, a thick film insulator 6 as an interlayer insulator is formed.

Next, a thick film insulator 6 is formed as shown in FIG. 2(b) by printing a conductor (-) for thickening, such as copper paste or nickel paste, and firing it in a neutral atmosphere. A first layer wiring pattern 8 made of a thick film conductor is electrically connected to the first layer wiring pattern 5 through the opening 7 .

Similarly, if necessary, an interstory insulator made of a thick film insulator, and a wiring pattern made of a thick film conductor or formed in the same process as the first layer wiring pattern using the interlayer insulator as a base conductor. A multilayer wiring board is produced by alternately laminating the above.

In this way, according to this example, a multilayer wiring board is obtained in which nine turns of wiring made of a thin copper film or a thick film conductor are laminated via an interlayer insulator made of a thick film insulator. The wiring pattern consisting of is the wiring No. 4 consisting of a thin film of gold? It is much cheaper than the wiring pattern.Moreover, since the main turn of the wiring is patterned by etching, it is possible to form a fine main turn with a line width of about 40 microns, for example.

Further, since a thick film insulator with good thermal conductivity can be used as the interlayer insulator, it is convenient when mounting a high power LSI chip f% on a substrate.

Since wiring patterns can be formed using thick film conductor pastes such as copper paste and kel paste, which are fired in a neutral atmosphere, it is possible to form wiring patterns consisting of four turns of fine wiring made of thin copper film and thick film conductors. Since a multi-circuit board can be obtained by combining the wiring arm turn, by using the latter wiring AI pattern in the part where large current flows, it becomes possible to sufficiently support the mounting of high power LSI chips. Thick film conductors made of copper paste not only have excellent electrical conductivity, but also have good soldering properties and are resistant to solder reach.
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FIG. 1 is a process diagram of an embodiment of the present invention, and FIG. 2 is a process diagram of an embodiment in which the invention is applied to the manufacture of a multilayer wiring board.

1... Base (underlying insulator), 2... Copper thin film, 3...
・Photoresist, 4...Copper aluminate, 5...
Wiring/IP turn made of copper thin film, 6... Interlayer insulator (base insulator) made of thick film insulator, 7... Opening 8
...Wiring 1 made of thick film conductor or copper thin film? ter0 Applicant's agent Patent attorney Takehiko Suzue: a;
Figure 1

Claims (5)

[Claims] (1) Form a copper thin film on the base insulator, apply 7-photoresist on it, expose and develop it, and after this exposure and development, 7-photoresist! After selectively etching and removing the copper thin film, the photoresist is removed, and then baking is performed in a neutral atmosphere at a temperature higher than the temperature at which the copper thin film reacts with the underlying insulator. Thin film is the method. (2) The method for manufacturing a wiring board according to claim 1, wherein the base insulator is a base of the wiring board. (3) The base insulator is an interlayer insulator in a multilayer wiring board, and is formed by printing a thick film insulator paste and baking it in a neutral atmosphere.Claim 1 A method for manufacturing a wiring board as described in Section 1. (4) The method for manufacturing a wiring board according to claim 1, which is a wiring i4 turn in a Noreen multilayer wiring board made of a copper thin film. (5) Wiring/arm turn thick film conductor made of copper thin film (
- Wiring made of thick film conductor formed by printing and firing in a neutral atmosphere/? 2. The method of manufacturing a wiring board according to claim 1, wherein the wiring board together with the turn constitutes a turn in a multilayer wiring board.