JP3369751B2 - Hybrid integrated circuit device and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid integrated circuit device and a method of manufacturing the same, and more particularly to a hybrid integrated circuit device in which moisture resistance deterioration is prevented and a method of manufacturing the same.

[0002]

2. Description of the Related Art Generally, there is a hybrid integrated circuit device as shown in FIG. 13, in which an anodic oxide film is formed on the surface of an Al metal substrate, and Cu conductive means is adhered on this by an insulating adhesive resin. Then, a semiconductor element or a circuit element is fixed to the conductive means and utilized as a hybrid integrated circuit device.

Therefore, since this metal substrate has a high thermal conductivity, the heat of a power element or the like, which generates a large amount of heat, serves as a heat sink for the metal substrate to suppress the temperature rise of the element, or the metal substrate is used as a heat sink or a chassis. When attached, the metal substrate has excellent heat conduction, and thus can efficiently release heat to the outside. Examples of these documents include POWE.
R QUALITY.OCTOBER 1993 PROCEEDING P.39 ~ P.51 `` Inte
lligent power IC incorporated active converter / in
verter in one unit ", or 1993, IEEE SEMI-THERM S
ymposium `` Thermal Design Andstructure of Thick Fi
lm Hybrid IC Based on Insulated aluminum Substrat
e "etc.

More specifically, the metal substrate 1 is
Anodized films 2 and 3 shown by dots are provided, and conductive means 5 made of Cu is provided on the surface of the anodized film via an insulating adhesive resin 4 shown by X. Here, the conductive means is a wiring, a region for fixing the semiconductor element 6 or a circuit component with an island-shaped land or an integrated land, a pad for fixing a lead, and the like. The semiconductor element is, for example, a bare chip transistor or a bare chip IC, and the circuit component is a printing resistor, a chip resistor, a chip capacitor, or the like. If necessary, fine metal wires are wire-bonded and provided, for example, between the semiconductor element and the wiring or between the wirings for crossover.

Subsequently, the case 7 is brought into contact with the periphery of the metal substrate 1, and the resin 8 is injected into the space formed by the case 7 and the metal substrate 1. The case 7 and the metal substrate 1 are adhered to each other with an adhesive resin 9 shown by a circle.

[0006]

In the configuration of FIG. 13 described above, specifically, the adhesive resin 9 is a sheet-like member in which glass fiber is impregnated with epoxy resin, and the metal substrate 1
Was affixed to the abutting portion of and adhered. In addition, ordinary adhesives have been provided on the side surface and the surface for adhesion. However, in this structure, one out of 100 or less, but a defect occurred as a result of experiments such as a moisture resistance test.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems. Firstly, a conductive means is attached to one surface of a metal substrate on which the anodic oxide film is not provided, via an adhesive resin. And a case for forming a resin injection space by making contact with the periphery of the surface of the metal substrate and using this metal substrate as the bottom surface.

Second, the strip-shaped region from which the oxide film has been removed is
It is a solution to the problem that it is provided on the inner side of the metal substrate region that comes into contact with the case, and the resin is bonded to the band-shaped region. Thirdly, the problem is solved by providing the interface exposed portion between the adhesive resin and the oxide film inside the contact area of the case. Fourthly, the problem is solved by cutting the cracks in the oxide film communicating from the periphery of the metal substrate to the semiconductor element disposition region in the middle.

Fifthly, the problem is solved by forming an anodic oxide film on only one surface of the metal substrate and bringing a case into contact with the surface of the other metal substrate. Sixth, after forming the anodic oxide film, after forming the adhesive resin or after forming the conductive means through the adhesive resin, at least the anodic oxide film in the region inside the contact region between the case and the metal substrate is removed. That is the solution.

[0010]

As a result of the experiment, it has been found that pinholes or the like are formed in the interface between the adhesive resin 9 and the metal substrate 1 or in the adhesive resin itself to form a path through which moisture can enter. However, the semiconductor element 6 is very far from this path, and the insulating adhesive resin 4 itself has a thin flexibility of about 20 to 100 μm and has no cracks, and the interface between this resin and the oxide film 3 is the main moisture. It's hard to think it's a pass,
Moreover, it is difficult to think that the semiconductor element itself is deteriorated because the sealing resin 8 is present instead of the hollow structure.

Therefore, as a result of re-examination and specific investigation of the anodic oxide film 3, as shown in FIG. 11, cracks 20 were formed on the entire surface in the form of a cobweb in the anodic oxide film. This is because the anodic oxide film itself is hard and brittle, and is a material that easily cracks during the heating and cooling steps. Further enlargement revealed that the crack was a V-shaped valley shown in FIG. This crack has a width of about 1 to 2 μm as shown by an arrow A, and when a liquid having good permeability such as an alcohol aqueous solution is dropped on the surface of the substrate, it is observed that the liquid is sucked into the crack so as to run. Has been done.
This is because after the anodic oxide film is formed, the thermal expansion of Al and the anodic oxide film or the anodic oxide film and the insulating resin 4 is performed by the heating and cooling treatment such as the adhesion of the conductive means 5 by hot pressing, the soldering and the hardening of the injected resin. I also helped with the difference in the coefficients and found that cracks were formed.

Further, since the periphery of the metal substrate 1 is punched out by a press, it was found that cracks were generated during this pressing process.
In particular, it was found that cracks were concentrated around the substrate than in other areas. Moreover, it was found that the cracks were connected from the surroundings to the area where the element was formed, and moisture could easily pass through.

Returning to FIG. 13, the moisture that has penetrated into the arrow A mainly passes through the interfaces 10 and 11, and in particular, the passage 10 abuts the side surface of the metal substrate 1. Membrane 3 allows more and more moisture to penetrate in the direction of arrow B through the cracks described above. Moreover, since the insulating resin 4 in the direction of the arrow C is very thin, and when the metal substrate is set to the GND potential, the conducting means other than the conducting means fixed at the GND potential have a certain potential with the substrate. It was found that moisture and impurities proceed in the direction of arrow C with the passage of time and easily reach the element through the passage.

Therefore, it was thought that the problem could be solved by blocking or eliminating this passage. Therefore, as described above, the first means is to provide an oxide film on the back surface to prevent scratches (keep the appearance shape in a clean state) and to form a moisture passage unless an oxide film is provided on the front surface. Therefore, the moisture resistance is improved. Secondly, if the strip-shaped region from which the oxide film is removed is provided inside the metal substrate region that contacts the case,
Since there are no cracks in this region, it is possible to cut the moisture passage and prevent moisture from reaching the semiconductor element.

Thirdly, like the second function, the interface between the adhesive resin and the oxide film serves as a moisture passage. Therefore, the interface exposed portion, which is the entrance of this passage, is brought into contact with the case (moisture passage). If it is provided on the inner side, there is a gap between the abutting portion of the case and the exposed interface portion, and this gap serves as a moisture blocking region, making it difficult for moisture to reach. Fourthly, in the crack of the oxide film which communicates from the periphery of the metal substrate to the region where the device is arranged, this communicating path can be cut in the middle, so that the moisture can be prevented from reaching the device.

Fifth, when a metal substrate is oxidized, for example, if a mask for preventing oxidation is provided on the surface of the other metal substrate to oxidize it, an oxide film is formed on only one surface and cracks are formed on the other surface. Since the generated oxide film is not formed, the passage of moisture can be blocked without adding a step of removing the oxide film having cracks. Sixth, if a strip-shaped anodic oxide film removal region is provided on the inner side of the contact region between the case and the metal substrate, the oxide film is substantially present on both sides unlike the case described in the fifth action. The warp of the substrate can be suppressed in the heat treatment step.

[0017]

EXAMPLES Before explaining the examples of the present invention, a manufacturing method will be briefly described with reference to FIG. Here, it is assumed that the removal area 20 of the present invention is not provided. First 0.5-3
There is a first step of preparing an Al metal substrate 21 having a thickness of about mm and forming anodic oxide films 22 on both surfaces. Here, the anodic oxide film 22 has a thickness of about 10 to 20 μm.

Subsequently, an adhesive resin 23 such as polyimide or epoxy resin is applied to the entire surface of the substrate, and 18 to 105 are applied on this.
There is a second step in which a copper foil of about μm is attached on the entire surface and hot pressed, so that the adhesive resin has a thickness of 20 to 100 μm. The hot press is 100 kg / sq. Cm. And 170 degrees, and in the case of polyimide and epoxy, it is about 3
In the case of an adhesive resin (polyimide or epoxy) having a low heat resistance with a filler contained therein for 0 minutes, the pressure is applied for about 60 minutes. After this, if necessary, a Ni plating process for the bonding point portion is performed. Further, if the previously plated copper foil is attached, the plating step can be omitted.

Subsequently, there is a third step of forming the conductive means 24 in a predetermined pattern with an etching solution such as ferric chloride. After that, in consideration of the stability of the printing resistance, the printing portion is coated with resin, and Considering the contact resistance of the printing resistance, there is a fourth step in which a silver paste is applied to the contact portion with the conductive pattern and both are sintered at about 150 degrees.

Next, there is a fifth step in which a printing resistor such as a carbon resistor is printed and baked at about 200 degrees, and the resin is overcoated to leave a solder printing portion in a later step, There is a sixth step that is fired at 150 degrees.
Further, solder cream is printed and melted at about 200 degrees, and the element 25 such as the chip resistor, the chip capacitor and the semiconductor chip is soldered, and there is a seventh step. After the wire bonding step, the case 26 is finally attached, Resin 27 is injected, and in the case of epoxy resin, 150
Cured in degrees.

In the embodiments shown in FIGS. 1 to 6, since the above steps may be slightly modified, they will be described when describing each embodiment. Then, share the drawing number used in the above-mentioned manufacturing method,
An example will be described. First, a metal substrate 21 which is the point of the present invention is prepared, a film serving as an oxidation resistant mask is attached to the upper surface and anodized, and an anodized film 22 is formed only on the back surface of the substrate 21. The metal substrate 21
The surface of is covered with an adhesive resin 23, and a conductive means 24 attached by the adhesive resin 23 is provided.

As can be seen from the plan view shown in FIG. 9, the conductive means 24 is soldered with the wiring 30, the land 31 on which the chip is mounted, the land 32 integral with the wiring, the bonding pad 33 and the external lead. A pad 34 or the like is used, and a semiconductor element 25 such as a bare chip transistor or an IC chip, and a circuit element such as a chip resistor, a printing resistor, and a chip capacitor are fixed via solder or the like.
The arrangement of the elements is the same in the embodiments shown in FIGS. 2 to 6, and will be omitted in the description of each embodiment thereafter. Further, although the undercoat film and the overcoat film have been described in the manufacturing flow, they are omitted here because they are not essential constituent elements.

Further, in order to achieve a circuit, a thin metal wire 36 is bonded between the semiconductor chip and the conductive means 24 and, if necessary, between the conductive means for crossover. Further, the case 26 is fixed to the metal substrate 21 via the adhesive material 28, and a sealing space having the metal substrate as a bottom surface and the case as a side surface is provided, and the sealing resin 27 is injected into this space.

The feature of the present invention resides in that the adhesive resin 23 is provided on the surface of the metal substrate 21 without providing the anodic oxide film 22. In other words, even if moisture reaches from the moisture inlet E to the outlet F, the edge portion of the anodic oxide film does not exist on the side surface (see FIG. 13), so it is difficult for moisture to reach the region where the element is fixed. Therefore, the deterioration of the element can be suppressed. In this embodiment, the metal substrate 21 is assembled without forming an anodic oxide film on the surface thereof, but it may be partially provided. In other words, cracks in the anodic oxide film are more likely to enter as the thickness increases, and are less likely to occur as the thickness decreases. Therefore, 5 μm, 1 μm considering safety
It has been found that cracks do not occur even if heat treatment is applied if formed below. Therefore, in the first step, the anodization of the front surface and the back surface may be performed separately, or after performing any of the first to third steps, sandblasting or the like may be performed until the film thickness becomes 1 μm.

The present invention does not have any problem even if the anodic oxide film is not provided on both surfaces. Also, if only one is provided, the thermal expansion coefficient of both sides will be different, causing the problem of warpage,
You can solve this. Next, a second embodiment will be described with reference to FIG. Since it is only slightly different from FIG. 1, only the relevant portion will be described here.

In other words, the anodic oxide film 22 is also provided on the surface of the metal substrate 21, conductive means is adhered on the anodic oxide film 22 via the adhesive resin 23, and the case 26 is brought into contact with the periphery of the substrate. The anodic oxide film and the adhesive resin have been removed to the inside of the part. Here, the metal substrate 21 and the case 26 have different shapes depending on how the leads are taken out. In FIG. 7, the lead 40 extends upward from the two sides, and a gel silicone resin is put in the region 41 where the element is arranged to absorb strain of the element, and then the epoxy resin. Since only the epoxy resin is provided in the lead placement region 42, the case 26 is provided with the partition plate 43. However, if silicone resin is not included,
Since it is not necessary to partition, the partition plate 43 is omitted.
FIGS. 9 and 10 explain the portion where the case 26 abuts. FIG. 9 shows the case without the partition plate 43.
Has a partition plate 43. The area indicated by X is the current section area of the case 26, and the area indicated by the dot is the removal area 20. The distance between the dotted line and the alternate long and short dash line shows how far inside the contact area. The longer this interval is, the more effective it is in suppressing the infiltration of moisture, but on the contrary, caution is required because the degree of freedom in element arrangement is lost. Further, in FIG. 8, the lead 40 is extended laterally, and the partition plate 4
3 enters the inside of the substrate and the partition plate 44 surrounding the leads is
It is composed of a separate body. The part indicated by the dotted line is the case 26
In the contact area of the element region 4 as in FIGS. 9 and 10.
An area where the anodic oxide film is removed is provided inside the contact area that surrounds 1 in a strip shape over the circumference.

Further, in FIG. 7, the leads are provided on the two sides, but some leads are provided on one side. In this case, the partition plate 44 of FIG. 8 is integrated with the case (one of the partition plates 44). Is removed), and the removal region is provided inside the contact region of the case surrounding the element placement region 41. Further, in FIG. 8, the lead 40 is provided only on one side, but it may be provided on two sides. In this case, the partition plates 44 and 45 of FIG. 41
The removal region is provided inside the abutting portion of the case surrounding the.

The feature of the present invention resides in that the anodic oxide film removal region is arranged inside the contact region between the metal substrate 21 and the case 26 surrounding at least the element arrangement region. Figure 2
Returning to the explanation, even if moisture reaches the element region from the moisture inlet E, the humidity inlet F of the anodic oxide film 22 has a certain distance from the abutting portion of the substrate, so that the humidity is indicated by F. It becomes difficult to reach the anodic oxide film 22 and the element can be prevented from changing with time due to moisture.

The cracks generated by pressing are particularly concentrated on the periphery of the substrate. By removing the cracks from the periphery, it is possible to remove the paths due to the concentrated cracks.
Prevents ingress of moisture. Since the cracked anodic oxide film 22 has good adhesiveness to the resin, the adhesive strength of the conductive means 24 is enhanced by leaving it intentionally unlike in FIG.

Further, in the manufacturing method of this embodiment, it is preferable that the removal region is formed after the first, second or third step. That is, in the case of etching, there is a risk of chip deterioration after the chips are fixed, and it is substantially impossible to sand the chips by sandblasting after the chips are fixed. Next, a third embodiment will be described with reference to FIG. The present invention is approximately the same as FIG. 2 and is different in that the anodic oxide film is left in the contact region of the case 26 as shown in the drawing.

As in the case of the second embodiment, considering that the adhesiveness is improved due to the presence of cracks, it is left in the contact area of the case 26. A feature of the present invention is that the interface exposed portion G between the adhesive resin 23 and the anodic oxide film 22 is provided inside the contact area of the case 26. Even if the portion indicated by the arrow F penetrates into moisture or cracks. However, since it is separated from the abutting portion of the case 26 by a certain distance, and because the resin 27 is sealed in the separated portion, it is difficult for moisture to reach the interface exposed portion G, which is a problem, Element deterioration can be prevented. Further, in the present invention, the adhesive resin 23 is removed from the anodic oxide film 22 that is in contact with the case 26, and the case and the metal substrate are fixed by the adhesive material that has entered the cracks in the anodic oxide film. The adhesiveness can be improved.

In the manufacturing method of the present invention, after the first step, the adhesive resin 23 may be selectively applied to selectively remove only the removed region. Although it can be applied to FIGS. 2 and 3, the ends of the anodic oxide film 22 and the adhesive resin 23 at the arrow G may not be self-aligned. That is, the end face of the anodic oxide film 22 may be covered with the adhesive resin 23. Next, a fourth embodiment will be described with reference to FIG. That is, the adhesive resin 23 remains at the contact portion between the case 26 and the metal substrate, unlike in FIG. This structure has the same effect as in FIG. 3 and, at the same time, can be simplified in the manufacturing method.

That is, in the first step, an anodic oxide film is formed on both surfaces of the metal substrate 21, and the adhesive resin 23 is applied to the entire surface without patterning. After this or after the third step, only the removed region 20 is formed. Can be removed at once. Further, a fifth embodiment will be described with reference to FIG. The present invention is similar to FIG. 2 except that the adhesive resin 23 extends to the end of the metal substrate 21 while covering the end of the anodic oxide film 22. Even if a large amount of moisture enters the adhesive 28 from the moisture inlet E, the edge of the anodic oxide film is separated from the contact region of the case 26, and the concentrated peripheral cracks are also removed. It is difficult for moisture to reach the anodic oxide film, and element deterioration due to moisture can be prevented.

In the present invention, a step of removing the anodic oxide film 22 is added after the first step, and the adhesive resin is applied to the entire surface. Finally, a sixth embodiment will be described with reference to FIG. The present invention is similar to FIG. 4, with the difference that the adhesive resin 23 is also covered on the removal area 20 of FIG. The effect is similar to that of FIG. 4, and as a manufacturing method, a step of removing the anodic oxide film 22 is added after the first step, and the adhesive resin is applied to the entire surface.

Although the anodic oxide film on the Al substrate has been described above as the oxide film, the metal substrate can be applied to any material with which the oxide film is formed, although the effect is large or small. Other than the oxide film, a thermal oxide film, a deposition such as vapor deposition, and the like can be applied.

[0036]

As is apparent from the above description, first, by providing the anodic oxide film only on one surface of the metal substrate and mounting the conductive means or the element on the other surface where the anodic oxide film is not provided. , Since the crack of the anodic oxide film does not exist on the mounting surface, even if moisture penetrates between the case and the metal substrate,
Since a path is less likely to enter the interface between the sealing resin and the adhesive resin or the adhesive resin and the metal substrate than in the conventional case, the moisture resistance deterioration can be significantly improved.

Further, instead of preparing the other surface on which the anodic oxide film is not provided, even if the anodic oxide film is provided on both surfaces in the first step and the other surface is ground to leave about 1 μm, The effect is achieved. In this case, the number of cutting steps is increased, but the breakdown voltage is slightly improved. Secondly, if the strip-shaped region from which the anodic oxide film is removed is provided inside the contact region between the case and the metal substrate, the contact region and the anodic oxide film, which are relatively susceptible to moisture infiltration, are separated, and Since the sealing resin or the adhesive resin is filled in the separated area, the resistance to infiltration of moisture can be significantly increased. Further, instead of removing all the anodic oxide film, even if about 1 μm remains, the same effect can be obtained.

Thirdly, by arranging the interface end portion of the adhesive resin and the anodic oxide film inside the contact portion of the case, the above-described second effect is obtained. Fourthly, by leaving the anodic oxide film in the contact area with the case, the adhesive resin or the adhesive can enter the cracks generated on the surface and improve the adhesiveness. Fifthly, when the metal substrate is anodized, if only one surface is anodized, a step of removing the anodized film in a later step is not necessary, and it can be achieved in almost the same manner as the conventional step.

Sixth, if a step of removing the anodic oxide film is added after the step of forming the anodic oxide film, after the formation of the adhesive resin or after forming the conductive means, the deterioration of the semiconductor element or the like in the subsequent step will occur. The anodic oxide film can be removed without inviting.

[Brief description of drawings]

FIG. 1 is a sectional view of a first hybrid integrated circuit device of the present invention.

FIG. 2 is a sectional view of a second hybrid integrated circuit device of the present invention.

FIG. 3 is a sectional view of a third hybrid integrated circuit device of the present invention.

FIG. 4 is a sectional view of a fourth hybrid integrated circuit device of the present invention.

FIG. 5 is a sectional view of a fifth hybrid integrated circuit device of the present invention.

FIG. 6 is a sectional view of a sixth hybrid integrated circuit device of the present invention.

FIG. 7 is a diagram illustrating a case.

FIG. 8 is a diagram illustrating a case.

FIG. 9 is a plan view of a metal substrate.

FIG. 10 is a plan view of a metal substrate.

FIG. 11 is a diagram illustrating a surface state of an anodized film.

FIG. 12 is a concrete view of a crack.

FIG. 13 is a cross-sectional view of a conventional hybrid integrated circuit device.

[Explanation of symbols]

20 removal area 21 metal substrate 22 Anodized film 23 Adhesive resin 24 Conductive means 25 Semiconductor element 26 case 27 resin 28 Adhesive resin 30 wiring 31,32 land 33 Bonding Pad 34 pads 35 resistor 36 thin metal wire 41 element placement area 42 Lead placement area 43,44 partition boards

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 23/02 H01L 23/12 H01L 23/28 H01L 25/04 H01L 25/18

Claims (3)

(57) [Claims] 1. A metal substrate having anodic oxide films formed on both surfaces, a conductive means attached on the anodic oxide film on the metal substrate via an adhesive resin, and electrically connected to the conductive means. A semiconductor integrated device, a case for forming a resin injection space by contacting the anodic oxide film on the surface of the metal substrate with the metal substrate as a bottom surface, and a resin injected into the injection space. A circuit device, wherein the strip-shaped region from which the anodic oxide film has been removed is provided inside the periphery of the metal substrate that abuts the case over the circumference ,
The resin is adhered to the strip-shaped region, and
Moisture that enters from the cracks that occur in front of the strip area
A hybrid integrated circuit device characterized by being prevented by a resin . 2. A metal substrate having anodic oxide films formed on both surfaces, a conductive means attached on the metal substrate via an adhesive resin, and a semiconductor element electrically connected to the conductive means. A hybrid integrated circuit device having at least a case in which a resin injection space is formed by contacting the periphery of the metal substrate with the metal substrate as a bottom surface, and a resin injected into the injection space. A hybrid integrated circuit device, wherein an interface exposed portion with the anodized film is provided inside a contact region of the case. 3. A metal substrate having anodic oxide films formed on both sides, conductive means attached to the metal substrate via an adhesive resin, and a semiconductor element electrically connected to the conductive means. A hybrid integrated circuit device having at least a case in which a resin injection space is formed by making the metal substrate a bottom surface and substantially abutting the periphery of the surface of the metal substrate, and a resin injected into the injection space. Has a crack substantially communicating from the periphery of the metal substrate to a region where the semiconductor element is arranged, and an interface exposed portion between the adhesive resin and the anodized film is provided inside a contact region of the case. A hybrid integrated circuit device characterized by the above.