JPH06268376A - Manufacture of multilayer circuit board - Google Patents

Abstract

PURPOSE:To provide high-reliability multilayer circuit boards, concerning to a manufacturing method for multilayer circuit boards for mounting LSIs, etc., with high density. CONSTITUTION:The title manufacture of multilayer circuit board has processes of protruding a conductor via 3 from the surface of a surface insulating layer 21 like a stump by etching the surface of a multilayer circuit board 10 selectively after the formation of the conductor via 3, of forming an insulating film 5 on the surface insulating layer 21 in such a shape as to contain the conductor via 3 protruding like a stump from the surface of the surface insulating layer 21, of grinding the surface of the surface insulating layer 21 flatly covered with the insulating film 5 and removing selectively only the insulating film 5 covering the tip part of the above-mentioned conductor via 3, of forming a wiring pattern 50 on the conductor via 3 whose tip part is exposed by the removal of the insulating film 5.

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 multi-layer circuit board on which LSIs and the like are mounted at high density. In recent years, the speed of semiconductor devices used in large-scale general-purpose computers and supercomputers has increased remarkably, and the delay time per gate has become less than 100 ps, and the transmission delay in the wiring part of the board relatively increases the computing speed of the computer. It has reached the point of influence.

As a result, a circuit board mounted on a computer is made of a ceramic material, which is capable of high-density mounting and is suitable for fine multilayer wiring, as an insulating material, and a conductor (including a conductor via and a wiring pattern). Attention has been paid to a multilayer ceramic circuit board (hereinafter referred to as a multi-layer circuit board) manufactured by integrally baking the above.

[0003]

2. Description of the Related Art FIGS. 2 (a), 2 (b), 2 (c) and 2 (d) are schematic side sectional views for explaining a conventional manufacturing process of a multilayer circuit board and its problems.

A conductor via 3 is formed in a surface insulating layer 21 of a multilayer circuit board 20 which is made by laminating a circuit board having a via portion and a conductor wiring layer (not shown) on the basis of a ceramic material. This conductor via 3 is on the surface
A wiring pattern 50 connected to is formed. The manufacturing process of this multilayer circuit board 20 will be described below with reference to FIGS. 2 (a), (b) and (c).
It will be explained based on (d).

1. First Step [See FIG. 2 (a)] Multilayer circuit board 20 formed by stacking a plurality of circuit boards
After the surface insulating layer 21 is formed on the surface portion of, the via hole 15 having a diameter of about 100 μm is formed at a predetermined position of the surface insulating layer 21. Then, the via hole 15 is filled with a conductive metal 8 in which a conductive metal such as copper is pasted.

2. Second step [see FIG. 2 (b)] When the step of filling the via hole 15 with the conductor metal 8 is completed, the via hole 15 is housed in, for example, a nitrogen atmosphere furnace and fired at a temperature of 1000 ° C. or less. The conductor metal 8 filled in the via hole 15 is solidified by this firing process. However, a minute gap Δ is formed between the outer peripheral surface of the conductor metal 8 and the inner peripheral surface of the via hole 15 by this firing step. This minute gap Δ is caused by the difference in the firing behavior (which means a phenomenon in which the respective structures change due to firing) of the ceramic material and the conductor metal 8 and the difference in the coefficient of thermal expansion.

3. Third step [see FIG. 2 (c)] After the firing step is finished, the surface of the multilayer circuit board 20 is next surface-ground. In this surface grinding, the surface roughness of the multilayer circuit board 20 roughened by the firing process (the surface roughness after the firing process is usually about 10 μm) is controlled to 1 μm or less, and
This is carried out in order to flatten the surface of the multilayer circuit board 20 by scraping off the conductive metal 8 that "sticks out" from the surface of the surface insulating layer 21. The conductor via 3 is formed in the via hole 15 by grinding the “protruding portion” of the conductor metal 8.

4. Fourth Step [see FIG. 2 (d)] When the step of forming the conductor via 3 is completed, the wiring pattern 50 is formed on the conductor via 3 this time. The wiring pattern 50 is formed by screen-printing a copper paste or the like and firing it.

[0009]

A conventional multilayer circuit board 20.
The wiring pattern 50 formed on the surface insulating layer 21 of the multilayer circuit board 20 is manufactured by the above process.
As shown in (b), (c), and (d), it is formed on the conductor via 3 which is in a positionally unstable state due to the existence of the minute gap Δ between the via hole 15. However, cracks α may be generated in the wiring pattern 50 due to a firing process performed thereafter.

Further, various processing solutions used in the subsequent steps such as a polishing step and a liquid phase step will soak into the minute gap Δ, so that these processing solutions react with the wiring pattern 50. There was also a problem such as disconnection failure.

[0011]

As shown in FIG. 1, a method of manufacturing a multilayer circuit board according to the present invention includes a step of selectively etching the surface of a multilayer circuit board 10 on which a conductive via 3 has been formed. A step of projecting 3 from the surface of the surface insulating layer 21 in a stump shape, and a step of forming the insulating film 5 on the surface insulating layer 21 including the conductor vias 3 protruding in a stump shape from the surface of the surface insulating layer 21. The step of selectively removing only the insulating film 5 covering the top of the conductor via 3 by subjecting the surface of the surface insulating layer 21 covered with the insulating film 5 to surface grinding, and removing the insulating film 5 The step of forming the wiring pattern 50 on the conductor via 3 whose top is exposed by.

[0012]

In this method of manufacturing a multilayer circuit board, since the step of filling the gap Δ generated between the conductor via 3 and the via hole 15 with the insulating film 5 is added, the gap between the conductor via 3 and the via hole 15 is increased. Various obstacles due to the presence of Δ (for example, impregnation and retention of various treatment liquids used in the polishing process or liquid phase process, and further, disconnection faults caused by the reaction of these treatment liquids with the wiring pattern 50) are extremely Efficiently resolved.

[0013]

The present invention will be described in detail below with reference to the drawings of the embodiments. 1 (a), 1 (b), 1 (c) and 1 (d) are schematic side cross-sectional views showing an embodiment of the present invention in the order of steps. The code is attached.

The method of manufacturing a multilayer circuit board according to the present invention is
As shown in Figures 1 (a), (b), (c), and (d), the conductor via 3
A step of selectively projecting the surface of the formed multilayer circuit board 10 to project the conductor via 3 in a stub shape from the surface of the surface insulating layer 21, and a conductor via projecting from the surface of the surface insulating layer 21 in a stub shape. And a step of forming an insulating film 5 on the surface of the multilayer circuit board covered with the insulating film 5.
A step of selectively removing only the insulating film 5 covering the top of the conductor via 3 by surface grinding 10 and a wiring pattern on the conductor via 3 having the top exposed by the removal of the insulating film 5. And forming 50.

The multilayer circuit board 10 is manufactured by the following procedure. (1) 50 Wt% of alumina having an average particle size of about 2 μm and 50 Wt% of borosilicate glass are kneaded with a binder resin and a solvent such as acetone or 2-butanone (butanol) or a plasticizer to prepare a slurry.

(2) This slurry was coated on a polyester film and the thickness was adjusted to 300 with a doctor blade.
A green sheet is formed by processing so as to have a thickness of μm. (3) After punching this green sheet into a square having a side of about 200 mm, a predetermined portion is punched with, for example, a punch having a diameter of about 100 μm to form a through hole for forming a conductive via.

(4) Copper paste is filled in the through holes, and then a wiring pattern is screen-printed so as to cover the through holes. (5) A plurality of green sheets manufactured in this manner are stacked and laminated using a press.

(6) This was housed in a nitrogen atmosphere furnace and 1000
Baking at a temperature of ℃ or less. Hereinafter, a method for manufacturing a multilayer circuit board according to the present invention will be specifically described with reference to FIGS. 1 (a), 1 (b), 1 (c) and 1 (d). In addition,
The following steps are performed after the completion of the third conventional step [see FIG. 2 (c)], and the steps before that are the conventional steps [FIGS. 2 (a), (b) and (c)]. Since it is the same, the description is omitted.

1. The first step [see FIG. 1 (a)] CF fluorine such as ₄ compound or CF ₄ or the like fluorine-based compounds by a plasma etching method using a mixed gas mainly composed conductive via 3 formed later [ See Figure 2 (c)]
The surface insulating layer 21 of the multilayer circuit board 10 is selectively etched (the portion indicated by the chain double-dashed line is the portion to be etched) to project the conductor via 3 from the surface of the surface insulating layer 21 in a stub shape.

2. Second step [see FIG. 1 (b)] An insulating film 5 made of a silicon nitride film is formed on the surface portion of the multilayer circuit board 10 including the conductor vias 3 protruding in a stub shape from the surface of the surface insulating layer 21. . As a result, the insulating film 5 penetrates into the minute gap Δ formed between the inner peripheral surface of the via hole 15 and the outer peripheral surface of the conductor via 3 and fills the minute gap Δ, so that the conductor via 3 is extremely stable. Become.

3. Third step (see FIG. 1C) The multilayer circuit board 10 is surface-ground so that only the insulating film 5 formed on the tops of the conductor vias 3 is selectively removed. As a result, only the top of the conductor via 3 is exposed. The insulating film 5 formed on the portion other than the top of the conductor via 3 remains as it is to form an insulating layer.

4. Fourth step [see FIG. 1 (d)] Conductor via 3 with only the top exposed, and surface insulating layer
Wiring pattern on the insulating film 5 which remains on 21
Forming 50. Since the wiring pattern 50 is formed on the conductor via 3 whose position is stable by the insulating film 5 that has penetrated into the minute gap Δ, cracks as shown in FIG. It does not produce α. Also,
Since the insulating film 5 prevents the processing liquid used in the polishing process or the liquid phase process from seeping in, the multilayer circuit board 10 has no risk of causing an accident such as disconnection of the wiring pattern 50. Extremely stable.

Although the embodiment described above is intended for the multilayer circuit board 10 constructed by laminating a plurality of circuit boards,
This method can also be applied to individual circuit boards constituting the multilayer circuit board 10.

[0024]

As is apparent from the above description, the method for manufacturing a multilayer circuit board according to the present invention additionally includes a step of filling the gap between the conductive vias and the via holes in the firing step with the insulating film. Therefore, various obstacles caused by the existence of the gap between the conductive via and the via hole are effectively eliminated, and the reliability of the multilayer circuit board is significantly improved.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of an essential part showing an embodiment of the present invention in the order of steps.

FIG. 2 is a schematic cross-sectional side view of a main part for explaining a conventional manufacturing process of a multilayer circuit board and its problems.

[Explanation of symbols]

 3 Conductor via 5 Insulating film 8 Conductor metal 10,20 Multilayer circuit board 15 Via hole 21 Surface insulating layer 50 Wiring pattern α Crack Δ Minute gap

Claims (3)

[Claims] 1. A conductor via formed in a surface insulating layer (21)
A method for manufacturing a multilayer circuit board (10), wherein a wiring pattern (50) connected to (3) is formed on a surface portion of the wiring pattern (50), the surface of the multilayer circuit board (10) after forming a conductor via (3). A step of projecting the conductor vias (3) in a stump shape from the surface of the surface insulating layer (21) by selectively etching the conductive vias (3), and a conductor via (3) protruding in a stump shape from the surface of the surface insulating layer (21). )
Including the step of forming the insulating film (5) on the surface insulating layer (21), and the surface of the surface insulating layer (21) covered with the insulating film (5) is ground to the conductor via (3). ) Selectively removing only the insulating film (5) covering the top part of the wiring) and the wiring pattern (50) on the conductor via (3) whose top is exposed due to the removal of the insulating film (5). A method of manufacturing a multilayer circuit board, comprising: 2. A multilayer circuit board (10) after the conductor vias (3) are formed by applying a plasma etching method using a fluorine compound or a mixed gas containing a fluorine compound as a main component.
2. The method for manufacturing a multilayer circuit board according to claim 1, wherein the surface of the substrate is selectively etched. 3. The multilayer circuit board (10) is manufactured by using a slurry prepared by kneading a ceramic material containing about 50 Wt% of a glass material with a solvent and a plasticizer. A method for manufacturing the multilayer circuit board described.