JPS60170294A - Method of producing multilayer circuit board with pin - 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] The present invention relates to a multilayer wiring board used in high-performance computers/bucks. The present invention relates to a method of manufacturing a multilayer wiring ceramic substrate on which fine multilayer wiring is formed and a large number of input/output terminal bins arranged in a matrix on the back surface.

[Prior art]

Conventionally, this type of multilayer wiring board is, for example, Pro-cee.
dings 198030th glectronic
Components Conference page
283~p285 6 Multi-Layer Ceramic, Multi-chip Module”
mic.

As shown in the paper titled "Multi-Chip Module", an alumina ceramic substrate with multi-layered signal wiring layers as shown in Fig. 6 is used as the substrate, and furthermore, an array of signal wiring layers is arranged on the back side of the substrate. As shown in the flowchart of FIG. 5, the input/output bin is soldered and bonded after collectively sintering an alumina ceramic substrate containing multilayer wiring layers therein. Moreover, the firing of the board.

As shown in lines 1 to 5 on the right side of page 285, '
The process is carried out in a high temperature reducing atmosphere of 1550°C.

Furthermore, the pins are brazed after the board is baked at the same temperature as described above at 1550°C in hydrogen using a brazing agent such as silver solder.
It has been carried out at lower temperatures of about 800°C to 850°C.

However, although the pin method described above is an effective method for ceramic multilayer wiring boards containing internal molybdenum multilayer wiring layers as described above, after sintering the ceramic board, other conditions may be applied to the surface of the ceramic board. In multilayer wiring boards of the type in which fine wiring is formed, there are problems in the first order. That is, this type of ceramic substrate contains only through-hole conductors inside.

After sintering in a reducing atmosphere, a fine wiring layer is formed on the surface of the ceramic substrate, but this wiring layer must be formed under temperature and atmospheric conditions that do not damage the through-hole conductors contained within the ceramic substrate. Since the wiring layer formed under these conditions cannot withstand higher temperatures and harsher atmospheres, it is
[Object of the Invention] Therefore, an object of the present invention is to facilitate the formation of fine wiring on a ceramic substrate, and to provide a large number of input/output pins on the entire back surface of one substrate. An object of the present invention is to provide a method for manufacturing a multilayer wiring board that allows easy formation of a multilayer wiring board.

[Structure of the invention]

In order to achieve the above object, the present invention uses an insulating material and a thin film wiring material that can be fired at a temperature sufficiently lower than that required for sintering an alumina ceramic board as a multilayer wiring board. Furthermore, as the adhesive material for the bottle, the adhesive material is used, which can be adhesively bonded at a temperature lower than that required for forming the multilayer wiring.

That is, according to the present invention, a first step of forming a multilayer wiring layer consisting of an insulating film and a thin film conductor wiring that can be fired at a temperature lower than that of the front and back surfaces, and forming the multilayer wiring layer on the back surface of the ceramic substrate. There is obtained a method for manufacturing a multilayer wiring board with a bottle, which comprises a second step of bonding terminal pins using a metal adhesive that can be bonded in air at a temperature below the temperature required to form a multilayer wiring board.

〔Example〕

Next, the present invention will be explained in detail with reference to the drawings.

Common to these six figures, 1 is a ceramic substrate,
2 is a through hole wiring, 3 is a pin pad, 4 is a first insulating layer, 5 is a second insulating layer, 6 is a first via hole wiring, 7 is a second via hole wiring, 8 is a first wiring layer, 9 is a second wiring Layer, ]0 is emptying the input and output bins. ' In FIG. 1, the through-hole wiring 2 is provided so as to penetrate the front and back sides of the ceramic substrate 1. For the through-hole wiring 2, molybdenum, tungsten, or the like is used as in the prior art example described above. The bin pad 3 is integrally provided in advance when the ceramic substrate 1 is manufactured, and has a structure such that, for example, a molybdenum conductor film is plated with nickel and gold to protect it from oxidation.

FIG. 2 is a diagram showing a state in which a fine wiring layer is formed on the surface of the ceramic substrate 1 in the first step. The first insulating layer 4 is provided on the substrate to insulate the substrate from the first wiring layer 8, and includes a first via-hole wiring 6 for connecting the first wiring layer 8 and the through-hole wiring 2. Contains. The second insulating layer 5 is formed on the first insulating layer 4 and is provided to insulate the first wiring layer 8 and the second wiring layer 9. Polyimide is used as the material for the second insulating layer that connects to the second insulating layer 9. The firing temperature of polyimide is in the range of 600°C to 400°C, and firing in nitrogen is preferred.

By firing the polyimide, the through-hole wiring 2 in the substrate 1 is advantageously prevented from deteriorating due to oxidation or the like.

The polyimide insulating layers 4 and 5 are formed by first spin-coating polyimide on the substrate, drying it, coating it with photoresist, exposing and developing the desired pattern of guia holes 6 using a mask, and then applying a polyimide etching solution (usually K
The polyimide under the photoresist film is etched using a strong alkaline solution such as OH (a strong alkaline solution such as OH is used) through holes made in accordance with the through hole pattern in the photoresist. This opens the desired guia holes 6 in the polyimide.

The wiring layers 8 and 9 are formed by sputtering Cr and Pd onto the polyimide insulating film 4 in which the through holes 6 have been formed. C
r is formed as an adhesion layer with polyimide, and Pd is formed as an adhesion layer with Cu, which becomes a wiring conductor. After sputtering Cr and Pd on the entire surface of the insulating layer 4, a photoresist is applied thereon, and a desired pattern of the wiring 8 is exposed and developed using a mask, and the photoresist is removed according to the pattern of the wiring 8.

Next, when copper plating is performed using the sputtered Cr and Pd films as electroplated conductors, a copper thin film is formed according to the pattern of the wiring 8, and this becomes the first wiring conductor 8. Next, the photoresist is removed, and the excess Cr and Pd films other than the copper pattern area are removed using a Pd and Cr etching solution.
Formation of wiring layer 8 is completed. The same applies to the formation of the second insulating layer 5 and the second wiring layer 9.

Figure 3 shows the input/output pins 1 on the back side of the ceramic substrate-1 after forming fine wiring in the first step as shown in Figure 2.
0 is shown attached. Adhesion of the mold/10 to the back surface of the ceramic substrate 1 is performed as a second step.

After forming fine wiring on the surface in the first step, gold-tin brazing is applied onto the pin pads 3 on the back surface of the ceramic substrate 1, and then the input/output pins 10 are pressed against each other at 200°C.
A temperature of 600° C. is applied to melt the gold-tin brazing material, and the input/output pin O is bonded to the pin pad 3.

Here, gold-tin brazing filler metal is used as an example of brazing filler metal.
This is because the melting temperature of gold-tin brazing is relatively low at 200° C. to 300° C., and the adhesive strength is sufficiently stronger than that of so-called soldering materials such as tin-lead. Furthermore, since the temperature applied to melt the wax can be lower than 600° C., the wiring layers 8 and 9 and the insulating layers 4 and 5 formed on the surface of the substrate 10 will not be damaged by oxidation.

Fine wiring is formed on the surface as described above.

Moreover, a high-density multilayer wiring board having a large number of input/output pins on the back surface can be obtained. Moreover, since the input/output pins 10 are bonded in the last process, the board 10 is bonded in the first process.
In the process of forming fine wiring on the front surface, the pins 1o are not bonded to the back surface of the substrate 1, so that fine wiring can be easily formed on the front surface without the pins on the back surface becoming an obstacle.

〔Effect of the invention〕

As explained below, by employing the manufacturing method according to the present invention, it is possible to easily realize a high-density multilayer wiring board having fine wiring formed on the front surface and a large number of input/output pins on the back surface. .

[Brief explanation of drawings]

FIGS. 1 to 6 are diagrams showing the method of manufacturing a multilayer wiring board according to the present invention in order of steps.

Claims (1)

[Claims] 1. A first method for forming a multilayer wiring layer consisting of an insulating film and thin film conductor wiring, which can be fired at a temperature lower than the sintering temperature of the ceramic substrate, on the surface of a ceramic substrate including through-hole conductor wiring that penetrates the front and back sides inside. and a second step of bonding a terminal bottle using a metal adhesive that can be bonded in air at a temperature below the temperature required to form the multilayer wiring layer on the back surface of the ceramic substrate. Substrate manufacturing method.