JP2656120B2 - Manufacturing method of package for integrated circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an integrated circuit package in which an integrated circuit is mounted on a substrate via a multilayer wiring board.

2. Description of the Related Art There is known an integrated circuit package in which an integrated circuit is mounted on a multilayer wiring board having a small dielectric constant, for example, using a polyimide resin as an insulating film to increase the signal speed.

[Problems to be Solved by the Invention] An insulator having a small dielectric constant generally has poor thermal conductivity. Taking polyimide resin as an example, the thermal conductivity is 1/100 smaller than that of alumina ceramics generally used for substrates.

Therefore, the heat release rate of the heat generated by the integrated circuit is low, and the integrated circuit to be mounted is thermally limited.

Therefore, for example, a structure in which a heater is directly joined to an integrated circuit to be mounted is considered. This means that the integrated circuit is face down (the wiring side faces the surface of the package)
It is mounted on a package, and a sealing cap serving as a radiator is joined to the back surface of the integrated circuit.

However, in this type, when the sealing cap is attached to the package, the integrated circuit and the sealing cap need to be thermally coupled. Management is required. In other words, those in which the radiator is joined to the integrated circuit have technical problems in mounting and assembling.

SUMMARY OF THE INVENTION An object of the present invention is to provide an integrated circuit package that is easy to mount and assemble an integrated circuit and that has excellent heat dissipation of heat generated by the integrated circuit.

Means for Solving the Problems In order to achieve the above object, a method for manufacturing an integrated circuit package of the present invention employs the following technical means.

Integrated circuit packages consist of a substrate with excellent thermal conductivity,
A multi-layer wiring board is provided on the surface of the substrate and has a multiplicity of wiring films composed of an insulating film having a low dielectric constant and a conductor film. An integrated circuit is mounted on the surface of the multi-layer wiring board.

The multilayer wiring board includes a heat dissipation via extending from the substrate to the integrated circuit, and the multilayer wiring board including the heat dissipation via sequentially repeats the second to fifth steps after the next first step. Formed.

A first step of forming a conductive base film serving as a base for electrolytic plating on the surface of the substrate;

A second step of selectively forming a conductive film on the surface of the base film by electrolytic plating;

A third step of forming a conductive pillar on the surface of the conductive film by an electrolytic plating method.

The unnecessary base film is removed, the conductive film including the base film and the conductive film is covered with an insulating material having a low dielectric constant together with the conductive pillar, and the surface of the insulating material is polished to form the insulating film. The fourth step to be performed.

A fifth step of forming a base film connected to the conductor pillar on the surface of the insulating film.

[Operation] When the integrated circuit mounted on the surface of the multilayer wiring board generates heat, the heat generated by the integrated circuit is transmitted to the substrate via the heat dissipation via. Since the substrate has excellent thermal conductivity, the substrate efficiently dissipates heat transmitted from the heat dissipation via.

[Effect of the Invention] In the present invention, since the integrated circuit is mounted on the surface of the multilayer wiring board, the heat generated by the integrated circuit is efficiently radiated from the substrate via the heat radiation via. As a result, heat generated by the integrated circuit to be mounted can be efficiently radiated without complicating the mounting method of the integrated circuit.

Example Next, a method for manufacturing a package for an integrated circuit of the present invention will be described.
Description will be made based on one embodiment shown in the drawing.

(Configuration of First Embodiment) FIGS. 1 to 11 show a first embodiment of the present invention.
FIG. 1 is a sectional view of an integrated circuit package on which an integrated circuit is mounted.

The integrated circuit package 1 includes a substrate 2 and a multilayer wiring board 3 formed on one surface of the substrate 2. One or a plurality of integrated circuits 4 are mounted on the surface of the multilayer wiring board 3. I have.

The substrate 2 is a multi-layer substrate 2 made of an insulating material having excellent thermal conductivity (eg, alumina, aluminum nitride, etc.). Specifically, a substrate 2 using alumina is shown as an example.
The wiring pattern 5 is printed on a green sheet made of alumina as a main material. Next, a plurality of the green sheets are stacked and fired at a high temperature in a hydrogen furnace in a humid atmosphere. The wiring pattern 5 in the substrate 2 is arbitrarily connected to the conductive via 6 of the multilayer wiring board 3 described below. The wiring pattern 5 in the substrate 2 is
Are connected to a plurality of pins 7 fixed to the respective pins.

The multilayer wiring board 3 is formed by laminating a large number of wiring layers 11 each including an insulating film 8 made of an insulating material having a low dielectric constant (for example, polyimide resin) and a conductive film 10.

The multilayer wiring board 3 is provided with a plurality of heat dissipation vias 12 extending from the surface of the substrate 2 to the integrated circuit 4 to be mounted. In other words, the heat dissipation via 12 is a substantially rod body having excellent thermal conductivity and is a means for thermally connecting the integrated circuit 4 to be mounted and the substrate 2.

Next, a manufacturing process of the heat dissipation via 12 will be described with reference to FIGS.

a1) First, a conductive base film 13 (for example, a two-layer metal film in which a Cu thin film is formed on the surface of a Cr thin film) serving as a base for electrolytic plating is formed on the surface of the substrate 2 by sputtering. 2).

b1) A photoresist 14 is applied on the base film 13, and after pattern exposure is performed, the photoresist 14 is removed only in a portion where the conductor film 10 is formed by a development process (see FIG. 3). The width of the conductor film 10 is formed to be substantially the same as the diameter of the conductor pillar 15 described below, or slightly larger than the diameter of the conductor pillar 15.

c1) A conductive film 16 made of Cu or Cu-Ni is formed by electrolytic electrolytic plating on the portion where the photoresist 14 has been removed (see FIG. 4).

d1) Next, a photoresist 17 is applied, and through exposure and development processes, a via hole having a diameter of 20 to 200 _μm is formed (see FIG. 5).

e1) Conductive pillars 15 are formed in the via holes formed in d1) by electrolytic plating of Cu having excellent conductivity and thermal conductivity (see FIG. 6).

f1) After removing the unnecessary photoresist 17, the unnecessary underlying film 13 is removed by etching (see FIG. 7). Through this step, the conductor film 10 including the base film 13 and the conductive film 16 is formed.

g1) A polyimide resin 18 which is an insulating material having a low dielectric constant and excellent heat resistance is applied so as to cover the conductor pillars 15 and cured (see FIG. 8).

h1) The surface of the cured polyimide resin 18 is polished to expose the head of the conductor post 15 (see FIG. 9). By this step, an insulating film 8 having a thickness of, for example, 20 _μm is formed.

That is, in the steps a1) to h1), the wiring layer 11
A layer is formed.

i1) A base film 13 is formed on the surface of the insulating film 8 by sputtering, a photoresist 19 is applied, pattern exposure is performed, and then only the portion where the conductor film 10 is formed by the development process is subjected to photoresist. 19 is removed (see FIG. 10).

Thereafter, by repeating the above-described steps c1) to i1), the wiring layer 11 is laminated, and the multilayer wiring board 3 having a plurality of heat dissipation vias 12 reaching the integrated circuit 4 from the surface of the substrate 2 is obtained. It is formed.

That is, the above a1) represents the first step of the present invention, and the above b)
1) and c1) represent the second step of the present invention, and the above d1) and e1)
Indicates the third step of the present invention, f1), g1) and h1) indicate the fourth step of the present invention, and i1) indicates the fifth step of the present invention.

j1) Then, on the surface of the multilayer wiring board 3, a conductive film 16 is formed in the portion where the photoresist 19 has been removed in the last step i1). Thereafter, unnecessary portions of the photoresist 19 and the base film 13 are removed (see FIG. 11).

The surface of the multilayer wiring board 3 where the integrated circuit 4 is mounted is covered with a conductive film 10 and, together with the conductive film 10 for conduction which is connected to the integrated circuit 4 via the bonding wires 20, is subjected to gold electrolytic plating. Is given.

The heat dissipation vias 12 are formed at the same time as the signal, power, or ground conduction vias 6 in the multilayer wiring board 3.

The integrated circuit package 1 having the above structure is provided with a heat dissipation via.
IC, LS, etc. are placed on the surface of the multilayer wiring board 3 where the 12 is disposed.
An integrated circuit 4 such as I or super LSI is mounted. Then, the mounted integrated circuit 4 is connected to the conductive film 10 on the surface of the multilayer wiring board 3 by bonding wires 20, and is connected to the substrate 2 via the conductive via 6 and the wiring pattern 5 in the substrate 2. Is electrically connected to the pin 7 fixed to the
Then, the sealing package 21 is attached to the integrated circuit package 1 on which the integrated circuit 4 is mounted, and the integrated circuit 4 is sealed.

(Operation of Embodiment) The operation of the heat dissipation via 12 formed in the multilayer wiring board 3 will be described.

When the integrated circuit 4 mounted on the surface of the multilayer wiring board 3 generates heat, the heat generated by the integrated circuit 4 is transferred to the substrate via the conductor film 10 formed on the mounting portion of the integrated circuit 4 and the plurality of heat dissipation vias 12. Transfer to 2. Specifically, the heat of the integrated circuit 4 is transferred to the conductor film 10, the conductor pillar 15, the conductor film 10, the conductor pillar 15, and the conductor film 10 on the surface.
, And finally heat is transmitted to the substrate 2. The substrate 2 has excellent thermal conductivity and an area larger than that of the multilayer wiring board 3. Therefore, the substrate 2 efficiently radiates the heat transmitted from the heat radiation via 12 into the air.

(Effects of the Embodiment) For example, even when the integrated circuit 4 generating a large amount of heat is mounted, the generated heat is transmitted to the substrate 2 through the plurality of heat radiation vias 12 and is efficiently radiated by the substrate 2. . For this reason, the range of the integrated circuit 4 that can be mounted is expanded as compared with the related art.

The mounting method of the integrated circuit 4 to be mounted is the same face-up as the conventional one (the wiring surface faces the surface), so that the bonding wires 20 can be easily bonded. Also,
Since the back surface of the integrated circuit 4 is bonded to the multilayer wiring board 3, the integrated circuit 4 can be easily mounted on the integrated circuit package 1.

In addition, since the generated heat is efficiently dissipated, the integrated circuits 4 on the high-speed processing day can be mounted at a high density. As a result, a lightweight, compact, high-speed, high-performance electric circuit can be realized.

Further, the heat dissipation via 12 is formed simultaneously with the conduction via 16. For this reason, a special device for forming the heat dissipation via 12 is not required, and a manufacturing process for the heat dissipation via 12 is also unnecessary. As a result, the integrated circuit package 1 having the heat dissipation vias 12 can be provided at low cost.

(Second Embodiment) FIGS. 12 to 19 show a second embodiment of the present invention.
This embodiment shows a modification of the method for manufacturing the multilayer wiring board (see the first embodiment) (a modification of the fourth step). This embodiment is suitable when the required insulating film 8 is relatively thick and a sufficient height cannot be obtained by forming the conductor pillars 15 by electrolytic plating. Note that the same reference numerals as those in the above embodiment indicate the same functional objects.

a2) In the same steps as a1) to f1) of the first embodiment, a conductor film 10 and a conductor pillar 15 are formed on the surface of the substrate 2 (see FIG. 12).

b2) Next, the conductor pillars 15 are buried, and a sufficiently thick polyimide resin 18 is applied and cured (see FIG. 13).

c2) Polish the surface of the cured polyimide resin 18 (No. 14)
See figure). Through this step, an insulating film 8 having a thickness of, for example, 30 _μm is formed. In this embodiment, since the insulating film 8 is thick, the conductor pillar 15 is not exposed from the surface of the insulating film 8.

d2) On the surface of the insulating film 8, an aluminum thin film 22 is formed by sputtering as a plasma etching mask (see FIG. 15).

e2) A photoresist 23 is coated on the aluminum thin film 22 and subjected to pattern exposure.
The photoresist 23 is removed only in the upper part of the 15 (16th
See figure).

f2) Subsequently, unnecessary aluminum thin film 22 is removed by etching (see FIG. 17).

g2) Further, unnecessary photoresist 23 and part of the insulating film 8 on the conductor pillar 15 are removed by O ₂ plasma etching (see FIG. 18). By this processing, the top of the conductor pillar 15 is exposed.

h2) Then, the aluminum thin film 22 is removed, and the base film 13 is formed on the surface of the insulating film 8 in the same step as i1) and j1) of the first embodiment.
Then, a conductor film 10 made of a conductive frame 16 is formed (see FIG. 19).

Then, by repeating the above steps, the wiring layer
11 are laminated to form a multilayer wiring board 3 having a plurality of heat dissipation vias 12.

(Third Embodiment) FIGS. 20 to 24 show a third embodiment of the present invention.
This embodiment also shows a modification of the method for manufacturing the multilayer wiring board (see the first embodiment) (a modification of the fourth step). In the present embodiment, the degree of adhesion of the film formed on the surface of the conductor film 10 is increased. Note that the same reference numerals as those in the above embodiment indicate the same functional objects.

a3) In the same steps as a1) to h1) of the first embodiment, a wiring layer 11 having a polished surface is formed (see FIG. 20).

b3) A polyimide resin of the same material as the insulating film 8 is applied again on the polished surface of the wiring layer 11 and cured at a predetermined temperature.
An insulating thin film 24 is formed (see FIG. 21).

c3) A photoresist 25 is applied to the surface of the insulating thin film 24 (see FIG. 22).

d3) Exposure, development, and etching of the insulating thin film 24 expose the top of the conductive pillar 15 (see FIG. 23).

e3) Next, the photoresist 25 is removed, and the polyimide resin is cured (see FIG. 24). Thus, the insulating thin film 24 is formed on the polished surface of the insulating film 8, and as a result, the wiring layer 11 having the insulating thin film 24 on the surface is formed.

Then, by repeating the above steps, the wiring layer
11 are laminated to form a multilayer wiring board 3 having a plurality of heat dissipation vias 12.

(Modification) In the present embodiment, an example in which the heat of the integrated circuit 4 is radiated by the substrate 2 is shown. However, a radiator is attached to the substrate 2, and the heat is transmitted to the substrate 2 via the heat radiation via 12. The heat may be efficiently radiated into the air by the radiator.

The numerical values (thickness, width, diameter, height, etc.) and materials described in the examples are merely examples, and the present invention is not limited to these numerical values and materials.

[Brief description of the drawings]

1 to 11 show a first embodiment of the present invention. FIG. 1 is a sectional view of an integrated circuit package on which an integrated circuit is mounted, and FIGS. It is explanatory drawing which shows a process. FIG. 12 to FIG. 19 are explanatory views of the manufacturing process of the heat dissipation via shown in the second embodiment. FIG. 20 to FIG. 24 are explanatory views of the manufacturing steps of the heat dissipation via showing the third embodiment. In the figure, 1 ... Package for integrated circuit 2 ... Board, 3 ... Multilayer wiring board 4 ... Integrated circuit, 8 ... Insulating film 10 ... Conductor film, 11 ... Wiring layer 12 ... Heat dissipation via, 13 …… underlayer 15 …… conducting pillars, 16 …… conductive film

Claims (1)

(57) [Claims] 1. A multi-layer wiring board comprising a substrate having excellent thermal conductivity and a plurality of wiring layers provided on a surface of the substrate and comprising an insulating film having a low dielectric constant and a conductive film. An integrated circuit package on which an integrated circuit is mounted on a surface of a multilayer wiring board, wherein the multilayer wiring board includes a heat dissipation via extending from the substrate to the integrated circuit, and the multilayer wiring board including the heat dissipation via Is a method for manufacturing a package for an integrated circuit, which is formed by sequentially repeating the second to fifth steps after the first step. A first step of forming a conductive base film serving as a base for electrolytic plating on the surface of the substrate; A second step of selectively forming a conductive film on the surface of the base film by electrolytic plating; A third step of forming a conductive pillar on the surface of the conductive film by an electrolytic plating method. The unnecessary base film is removed, the conductive film including the base film and the conductive film is covered with an insulating material having a low dielectric constant together with the conductive pillar, and the surface of the insulating material is polished to form the insulating film. The fourth step to be performed. A fifth step of forming a base film connected to the conductor pillar on the surface of the insulating film.