JP3203219B2 - Manufacturing method of hybrid integrated circuit device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a hybrid integrated circuit device, and more particularly to a method of manufacturing an Al substrate.

[0002]

2. Description of the Related Art As a substrate used in a hybrid integrated circuit device,
There are ceramics, printed boards, metal boards, and the like, which are used in various fields. Among these substrates, a metal substrate has excellent thermal conductivity, and is therefore applied to a power circuit, a substrate on which an element requiring heat radiation is mounted, and the like. In particular, Al substrates are often used because they are excellent in workability. For example, Japanese Patent Publication No. 46-13234 discloses an anodized surface of an Al substrate in detail.

That is, an Al 2 O 3 coating 2 is formed by anodizing both surfaces of an Al substrate 1 shown in FIG. 7, and conductive means 4, 5, 6, and 7 are attached via an insulating resin 3. Code 4
Is a wiring for connecting circuits, 5 is a lead pad for connecting external leads, 6 is a wire bonding pad, and 7 is an island. Circuit elements to be mounted are chip resistors, chip capacitors, semiconductor elements, and the like. Particularly, semiconductor elements (transistors, ICs, and the like) are mounted on lands 7, and the semiconductor elements and pads 6 are electrically connected via thin metal wires. It is connected to the. Although omitted in the drawing, leads are connected to the pads 5 as necessary, and the whole is sealed.

The Al2O3 film is excellent in corrosion resistance, abrasion resistance, and insulation properties, and is particularly useful as a withstand voltage characteristic between the Al substrate 1 and the conductive means 4 to 7, and also to prevent scratches on the back surface during transportation in each manufacturing process. It is something. However, as shown in Japanese Patent Publication No. 58-19157 (FIG. 8), a current flows due to the anodic oxidation of an electrolyte solution (for example, a sulfuric acid bath).
A honeycomb-shaped porous body layer 12 is formed on the surface of the Al substrate 1 in units of cylindrical or hexagonal column-shaped cells 11 having zero. This porous body corresponds to reference numeral 2 in FIG. In this porous body, a barrier layer (Al 2 O 3) of about 150 ° is initially formed in the pores, and since this layer is very thin, it is considered that Al is corroded through this part, and sealing treatment is performed. Was.

[0005]

However, when the pores are completely sealed, the pores are densely filled with aluminum hydroxide,
When this was heated to about 200 degrees, cracks occurred due to the difference in thermal expansion coefficient between aluminum hydroxide and Al. For this reason, as described in the above-mentioned publication, the treatment is performed in a hot water or steam atmosphere close to 100 degrees to form a semi-sealed hole 12 in the hole.

[0008] As can be seen from FIG. 8, aluminum hydroxide that blocks the pores is produced on the pole surface of the pores, but small pores are still produced in the center, which is called semi-sealed.
However, due to the anodization in a sulfuric acid bath, the surface of the hole 11
A film indicated by reference numeral 13 was formed, and it was found that this film was a layer containing a large amount of aluminum sulfate (Al2 (SO4) 3).

In addition, for example, the height of the cell is 5 to 20 μm.
m, the diameter of the hole is about 300-500 mm. After anodizing in a sulfuric acid bath, even if you try to remove a part of the sulfuric acid greed in the cell, the sulfuric acid water taken in the hole should be easily removed. The inability to do this is evident from capillary action. In addition, when the temperature and the humidity become high, the sulfuric acid is separated into ions, and moves to the insulating resin layer 3 and to the surface on which the wiring pattern is formed via the insulating resin layer 3, and between the Al substrate and conductive means (for example, wiring). In the case of the insulation life and fine pattern, there is a problem that the characteristics are deteriorated in various places such as the withstand voltage of the wiring.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. First, a step of forming an anodic oxide film on both surfaces of an Al substrate, and a step of forming an anodic oxide film on one surface of the Al substrate. Removing the anodized film, and bonding an insulating resin layer having conductive means (or a flexible sheet having conductive means) formed on the one surface to the Al substrate surface from which the anodized film has been removed. And mounting a circuit element on the conductive means.

Since the Al2O3 film is formed as thick as 5 to 20 .mu.m and has a structure that is hardly damaged, it is desirable to leave the Al2O3 film on the back surface of the substrate which is in direct contact with the manufacturing apparatus during the manufacturing process. Therefore, first, the entire surface is anodized, and only one surface is removed of this anodized film, and the other surface is Al2O3.
Since the film remains, it is possible to realize a structure in which the back surface is not scratched and the front surface does not show ions that adversely affect the characteristics.

Secondly, after removing the anodic oxide film on one surface, the Al substrate is immersed in high-temperature pure water or high-temperature steam to use a hydrated oxide film formed as an adhesive layer. Is the solution. The hydrated oxidized product obtained by this method has a needle-like crystal structure, and therefore has a high adhesiveness to an insulating resin. This product is about 2 μm even when it is thick, and the conventional Al 2 O 3 film has a thickness of 20 μm. Taking this into consideration, an adhesive layer with reduced thermal resistance can be realized.

Third, the electrode and the Al electrode are placed in the anodic oxidation bath so that one surface is thinner than the other surface to form an anodic oxide film.
Arranging the substrate and anodizing both surfaces of the Al substrate;
A step of dipping in an etchant of the anodic oxide film and maintaining the anodic oxide film on one surface until the anodic oxide film is substantially removed, and an insulating resin layer having conductive means formed on the one surface (or a flexible sheet having conductive means) And an Al substrate surface from which the anodic oxide film has been removed via an adhesive layer, and mounting a circuit element on the conductive means.

The thickness of the Al2O3 film on the mounting surface and the non-mounting surface can be changed by the arrangement of the electrodes and the arrangement of the substrate. Therefore, even if the Al2O3 film on one surface is removed, the Al2O3 film on the other surface can be left. Fourth, Al
Forming an antioxidant film on one surface of the substrate and anodizing the other surface to form an anodic oxide film; and an insulating resin layer having conductive means formed on the one surface (or having an electrically conductive means). This problem can be solved by attaching a flexible sheet) to the Al substrate surface from which the anodized film has been removed via an adhesive layer, and mounting a circuit element on the conductive means.

If a sheet having good chemical resistance is bonded as an antioxidant film, and the sheet is removed later, an Al2O3 film is not formed on one surface and an Al2O3 film is formed on the other substrate. A substrate can be realized. Fifth, after forming the anodic oxide film on the other surface, a hydrated oxide film formed by immersing the Al substrate in high-temperature pure water or high-temperature steam is formed on one surface. This will solve the problem.

Sixth, the problem is solved by removing a natural oxide film formed on an Al substrate before forming the hydrated oxide film. Since the hydrated oxide film is hardly generated due to the presence of the natural oxide film, a relatively thick film can be realized by removing the hydrated oxide film and forming a film. As described above, since the cells have holes, ions (divalent SO4 ions) that adversely affect the characteristics are taken in. Therefore, Al2O3 on the surface of the Al substrate serving as the mounting surface may be removed. However, since the adhesiveness between the Al metal surface and the insulating resin is very poor, the adhesion with the insulating resin is enhanced by providing an adhesive layer instead of Al2O3.

In consideration of connection with external equipment, a flexible sheet provided with conductive means may be attached to an Al substrate, such as an automobile, an air conditioner, a CD-ROM,
It is suitable for a motor or the like. In particular, considering the mounting atmosphere, it is conceivable that the ions come out. Therefore, it is also effective in such a case. Also, instead of Al2O3, a corrosion-resistant coating can be formed, and good characteristics can be obtained by forming a hydrated oxide coating of Al2O3 and AlOOH by a so-called boehmite treatment. Especially AlO
OH has strong corrosion resistance. Further, this hydrated oxide film is formed of high-temperature pure water and pressurized steam, and does not conduct electricity, so that a hole formed by anodic oxidation is not formed, and trapping of impurity ions can be prevented. In addition, since fine needle-like projections are generated on the surface, the adhesiveness to the insulating resin can be improved. Also, since this film is different from the case where current is forced to flow, it grows only up to about 2 μm, and is about 1/10 thinner than the conventional Al 2 O 3 film having a thickness of 20 μm, so that the thermal resistance is also lowered.

However, if a natural oxide film is formed on the Al substrate, the hydrated oxide is hardly generated and hardly reaches the thickness. Therefore, the growth of the hydrated oxide is prevented by removing the natural oxide film. Can be encouraged.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a hybrid integrated circuit device according to an embodiment of the present invention will be described. FIG. 6 is substantially the same as FIG. 7 of the conventional example except for the hydrated oxide film on the mounting surface, and is an embodiment. In other words, one surface of the Al substrate 1 is anodized to form the Al2O3 film 2, and the other surface is
Either an Al2O3 film is not generated, or an Al2O3 film is formed on both surfaces during the anodic oxidation, and then the Al2O3 is removed.

The point of the present invention is that an Al2O3 film generated by anodic oxidation is not used for the mounting surface of the Al substrate. As described in the conventional example, the surface of the hole 11 is a layer containing a large amount of aluminum sulfate (Al2 (SO4) 3) indicated by reference numeral 13 as shown in FIG. It turns out. Moreover, the height of the cell
The pore size is about 10 μm or more and the diameter of the pores is about 300 to 500 °. Even if the sulfuric acid is removed by anodic oxidation in a sulfuric acid bath, the sulfuric acid solution taken in the pores cannot be easily removed. It was clear from the phenomenon.

Therefore, if an anodic oxide film is not formed,
Since there is no hole, deterioration of characteristics can be prevented. Considering this point, a possible structure is as follows. Type 1: An Al2O3 film is left on the back surface of the substrate.

The reason is that the anodic oxide film is as thick as 20 μm, is excellent in corrosion resistance and abrasion resistance, and is hardly damaged during transportation during the manufacturing process. Accordingly, a corrosive solution such as an etchant does not reach Al via the flaws, so that a clean and reliable Al substrate can be realized. An Al2O3 film is applied to the non-mounting surface of the Al substrate (for example, the back surface when only one surface is mounted). The mounting surface is
An Al2O3 film is not formed or formed on both surfaces during anodic oxidation, and then removed. Then, the insulating resin layer or the flexible sheet to which the conductive means is attached is bonded via an adhesive layer.

Instead of the adhesive layer, a structure in which the surface of the Al substrate is matte or uneven is conceivable. In this step, a hydrated oxide film 21 subjected to boehmite treatment is formed as an adhesive layer. Type 2: Al is exposed on the back surface of the substrate, or a hydrated oxide film 21 is formed on the surface.

Type 1 is preferred. That is, scratches are likely to occur during transportation during the manufacturing process. 2μ of hydrated oxide 21
Since it can grow only about m, it is easy to be scratched. In addition, it is corroded by an etchant or the like via the scratches, resulting in poor aesthetics and reliability. However, to prevent this scratch and corrosion,
What is necessary is just to adhere a sheet excellent in corrosion resistance and abrasion.

The non-mounting surface of the Al substrate (for example, the back surface when only one surface is mounted) has no Al2O3 film and is used as a mounting surface on which sheets are bonded. The non-mounting surface of the Al substrate (for example, the back surface when only one surface is mounted) has no Al2O3 film and is used as a mounting surface to which sheets are bonded. The non-mounting surface of the Al substrate (for example, the back surface when only one surface is mounted) is used as a mounting surface on which a hydrated oxide film is generated and a sheet is bonded.

The non-mounting surface (for example, the back surface when only one surface is mounted) of the Al substrate is adopted as a mounting surface on which a hydrated oxide film is generated and a sheet is bonded. In the above configuration, the conductive means 4, 5, 6, and 7 shown in FIG. 7 are further attached via the insulating resin 3 or the flexible sheet 20. Reference numeral 4 denotes wiring for connecting circuits, 5 denotes lead pads for connecting external leads, 6 denotes wire bonding pads, and 7 denotes islands. This flexible sheet is preferably made of a polyimide film or polyethylene terephthalate.

The circuit elements to be mounted are a chip resistor, a chip capacitor, a semiconductor element, and the like. Particularly, the semiconductor element (transistor, IC, etc.) is mounted on the land 7, and the semiconductor element and the pad 6 are connected via a thin metal wire. And are electrically connected. Although omitted in the drawing, leads are connected to the pads 5 as necessary, and the whole is sealed. The sealing method employs a means having a shape such that a lid is put on the hybrid integrated circuit board, and generally employs a so-called case material for sealing. This structure is a hollow structure or a structure in which a resin is separately injected therein.

The semiconductor IC is sealed by transfer molding, injection molding, potting, or the like, in which a resin is applied to the IC chip 12 or the thin metal wire, which are well-known methods for molding a semiconductor IC. Subsequently, the hydrated oxide film formed by the boehmite treatment will be described. Boehmite coatings are mainly made of Al2O3 and Al
The latter AlOOH has strong corrosion resistance (acid resistance and alkali resistance). In addition, since it can be formed with high-temperature pure water and high-temperature steam, it is an environmentally friendly method in terms of waste liquid treatment.

In the production method, a hydrated oxide film is formed by chemical conversion treatment with high-temperature pure water and high-temperature pressurized steam. The reaction is
2Al and 4H2O produce 2AlOOH and 3H2.
Specifically, at the anode, 2Al → Al (3 +) + 3e (where () means plus trivalent). At the cathode, 3H2O + 3e → 3OH (-) + (2/3) H2 occurs as a reaction. , Al (3 +) + 2OH (-) → Al.O.OH + H
(+) 2Al (3 +) + 6OH (-) → Al2O3.nH2O +
(3-n) H2O (n = 0 to 3 n = 1 is called boehmite, n = 3 is called bayerite).

The boehmite film thus formed is a chemically stable and dense film, and has high adhesion to the Al substrate because it is formed from the Al substrate. Further, as shown in FIG. 4, it is a needle-like crystal film and has good adhesiveness to an insulating resin.
Further, the boehmite coating has a limit of about 1 μm, and the limit is about 2 μm even when ammonia or alcoholamine is added as a reaction accelerator. Therefore, it is a very thin film.
Since the O3 film has a thickness of 10 .mu.m or less, the thermal resistance can be made much smaller than before. In addition, when a natural oxide film is generated in forming this film, this reaction is very unlikely to occur, so it is better to remove the natural oxide film.

On the other hand, this boehmite film can grow only about 2 μm and is easily scratched by mechanical abrasion. Therefore, it is not preferable to form the boehmite film on the back surface of the metal substrate. That is, it is exposed to a corrosive liquid such as an etchant during the manufacturing process. In this case, the method can be implemented by bonding a resin sheet having excellent chemical resistance and abrasion resistance. In addition, if the step does not cause scratches, the boehmite film formed on the back surface has corrosion resistance, and thus can serve as a mask during etching.

Specifically, a method of anodizing an Al substrate,
A method of performing boehmite treatment will be described. 1 and 2
The method of forming a boehmite coating on the back surface in Type A is described. First, platinum negative electrodes 32 and 33 are provided in a container containing an aqueous sulfuric acid solution 30, and an Al substrate connected to a positive potential is inserted between them. Al applied positively
Oxygen ions move toward the substrate 34, and Al
2O3 films 35 and 36 are generated.

Subsequently, the Al 2 O 3 film 36 formed on one surface as shown in FIG. 2 is removed and immersed in high-temperature pure water 37.
Therefore, a boehmite coating 38 is formed on one surface.
Here, the Al2O3 film may be mechanically removed or chemically removed. The etchant for this chemical removal is caustic soda (about 10% NaOH)
I like it.

FIG. 3 is an example replacing FIG. 1, in which two substrates 40 and 41 are arranged opposite to each other between two negative electrodes and anodized. Since a stronger electric field is applied to the Al substrate surface facing the minus electrode than to the Al substrate surface facing each other, the Al 2 O 3 films 42 and 44
It is formed thicker than the l2O3 films 43 and 45. Therefore, if the Al substrate on which the Al2 O3 films having different thicknesses are formed is immersed in caustic soda 50 and the Al2 O3 film is etched as shown in FIG. 42 remains with a fixed film thickness. Therefore, by controlling the distance between the substrates, the growth rate, and the like in FIG. 3, an Al2O3 film having a film thickness similar to that of the related art can be formed on only one side.

In FIG. 1, even if the negative electrode 32 is omitted and anodic oxidation is carried out, similarly, a film having a different film thickness can be realized, and Al.sub.2 O.sub.3 can be left only on one side through the process of FIG. Therefore, thereafter, as shown in FIG. 2, a boehmite treatment can be performed to leave a boehmite film on one surface and an Al2O3 film on the other surface. In this case, during the boehmite treatment, the sealing reaction described in the conventional example occurs in the Al2O3 film, and the corrosion resistance can be improved.

Further, in FIG. 4, before the anodizing step of FIG. 1, a sheet 47 having excellent corrosion resistance is attached via an adhesive 46, and then anodized. As a result, only the other surface A
After the l2O3 film 36 is formed and the sheet is peeled off,
By performing the boehmite treatment as shown in FIG. 2, a boehmite film can be formed on one surface and an Al2O3 film can be formed on the other surface. Also in this case, the sealing reaction occurs as described above.

[0035]

As described above, first, a step of forming an anodic oxide film on both surfaces of an Al substrate, a step of removing the anodic oxide film formed on one surface of the Al substrate, An insulating resin layer having conductive means (or a flexible sheet having conductive means) formed on one surface and the Al substrate surface from which the anodic oxide film has been removed are adhered via an adhesive layer, and the conductive means is provided on the conductive means. And a step of mounting a circuit element. The mounting surface has no Al2O3 film, and the other surface can be formed with an Al2O3 film.

Since the Al 2 O 3 film is formed to be as thick as 5 to 20 μm and has a structure that is hard to be scratched, the Al 2 O 3 film is left on the back surface of the substrate in direct contact with the manufacturing apparatus during the manufacturing process, so that the scratches and scratches on the back surface are formed. Corrosion can be prevented. Second, after removing the anodic oxide film on one surface, the Al substrate is immersed in high-temperature pure water or high-temperature water vapor to form a hydrated oxide film, which has a needle-like structure. In addition, the adhesiveness with the insulating resin can be improved. The thickness of this product is about 2 μm even when it is thick. Considering that the thickness of the conventional Al 2 O 3 film is 5 to 20 μm, an adhesive layer having a reduced thermal resistance can be formed.

Third, the electrode and the Al are placed in the anodic oxidation bath so that one surface is thinner than the other surface to form an anodic oxide film.
Arranging the substrate and anodizing both surfaces of the Al substrate;
The thickness of the Al2O3 film on the mounting surface and the non-mounting surface can be changed by the step of dipping in the etchant of the anodic oxide film and maintaining it until the anodic oxide film on one surface is substantially removed. Therefore, even if the Al2O3 film on one surface is removed, the Al2O3 film on the other surface can remain, and a hydrated oxide film can be formed on one surface and an Al2O3 film can be formed on the other surface. .

Fourth, an Al 2 O 3 film is not formed on one surface by the step of forming an antioxidant film on one surface of the Al substrate and anodizing the other surface to form an anodic oxide film. A hybrid integrated circuit substrate having an Al2O3 film formed on the substrate can be realized. Fifth, after forming an anodic oxide film on the anodic oxide film on the other surface, a hydrated oxide film formed by immersing the Al substrate in high-temperature pure water or high-temperature steam is formed on one surface. Since this film has a needle-like structure, the adhesiveness to the insulating resin can be improved. The thickness of this product is about 2 μm even when it is thick,
Considering that the O3 film has a thickness of 5 to 20 .mu.m, an adhesive layer having a reduced thermal resistance can be formed.

Sixth, the formation rate of the hydrated oxide film can be improved by removing the natural oxide film formed on the Al substrate before forming the hydrated oxide film. Since the cells having the pores conventionally formed are removed as described above, chemicals, ions, heavy metals, and the like that adversely affect the characteristics are not taken in. Therefore, a hybrid integrated circuit device having improved withstand voltage characteristics and excellent in generating fine patterns can be realized.

The formation of the hydrated oxide film improves the adhesiveness to the insulating resin and, at the same time, reduces the thermal resistance because the film is thin, thereby realizing a hybrid integrated circuit substrate having higher heat dissipation. As described above, by adopting this manufacturing method, deterioration of the hybrid integrated circuit device can be prevented even in a severe mounting environment such as an automobile, an air conditioner, a CD-ROM, and a motor.
The reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating anodization employed in a method of manufacturing a hybrid integrated circuit device according to the present invention.

FIG. 2 is a diagram illustrating a boehmite process employed in the present invention.

FIG. 3 is a diagram illustrating another anodic oxidation employed in the method for manufacturing a hybrid integrated circuit device of the present invention.

FIG. 4 is a diagram illustrating another anodic oxidation employed in the method of manufacturing a hybrid integrated circuit device according to the present invention.

FIG. 5 is a diagram illustrating a method of etching the Al2O3 film generated in FIG.

FIG. 6 is a perspective view illustrating a hybrid integrated circuit device according to the present invention.

FIG. 7 is a perspective view illustrating a conventional hybrid integrated circuit device.

FIG. 8 is a view for explaining the structure of a conventional Al2O3 film.

FIG. 9 is a diagram illustrating a boehmite coating used in the hybrid integrated circuit device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Al substrate 2 Al2O3 film 3 Insulating resin 4-7 Conducting means 10 Hole 11 Cell 21 Boehmite coating 30 Anodizing bath 37 Boehmite treatment bath

Claims (6)

(57) [Claims] A step of forming an anodic oxide film on both surfaces of an Al substrate; a step of removing the anodic oxide film formed on one surface of the Al substrate; and a conductive means formed on the one surface. Attaching an insulating resin layer (or a flexible sheet having conductive means) to the Al substrate surface from which the anodic oxide film has been removed via an adhesive layer, and mounting a circuit element on the conductive means. A method for manufacturing a hybrid integrated circuit device, comprising: 2. The adhesive layer is a hydrated oxide film formed by removing the anodic oxide film on one surface and then immersing the Al substrate in high-temperature pure water or high-temperature steam. The method for manufacturing a hybrid integrated circuit device according to claim 1. 3. A step of disposing an electrode and an Al substrate in an anodic oxidation bath so that one surface is thinner than the other surface to form an anodic oxide film, and anodizing both surfaces of the Al substrate. A step of immersing in an etchant of an oxide film and maintaining the anodic oxide film on one surface until the anodic oxide film is substantially removed; and an insulating resin layer having conductive means formed on the one surface (or a flexible sheet having conductive means); Attaching the Al substrate surface from which the anodized film has been removed via an adhesive layer, and mounting a circuit element on the conductive means. A step of forming an antioxidant film on one surface of the Al substrate and anodizing the other surface to form an anodic oxide film; and an insulating resin layer having conductive means formed on the one surface. (Or a flexible sheet having conductive means) and the Al substrate surface from which the anodic oxide film has been removed through an adhesive layer, and mounting a circuit element on the conductive means. A method for manufacturing a hybrid integrated circuit device. 5. The adhesive layer is a hydrated oxide film formed by forming an anodized film on the other surface and then immersing the Al substrate in high-temperature pure water or high-temperature steam. The method for manufacturing a hybrid integrated circuit device according to claim 3 or 4, wherein 6. A method for forming a hydrated oxide film, comprising:
6. The method according to claim 2, wherein a natural oxide film formed on the substrate is removed.