JPH0823145A - Substrate for hybrid ic - Google Patents

Abstract

PURPOSE:To realize heat radiating property, insulating property and heat resistance by forming a thin-film circuit or thick-film circuit on the surface of a first ceramic substrate for heat radiation and piling and bonding an aluminum plate and a second ceramic substrate for heat radiation thereon respectively by an Al-Si based brazing material. CONSTITUTION:First, a substrate 10 for hybrid IC is formed by piling up and bonding a first ceramic substrate 11 for heat radiation, an aluminum plate 21 and a second ceramic substrate 22 for heat radiation in order by using an Al-Si based brazing material. Then a thin-film circuit or thick-film circuit 12 having a thick-film resistor 12a is formed on the surface of the substrate 11. Thus, the heat radiating property is further improved and the substrate 10 becomes more excellent in insulating property and heat resistance than an insulation layer of an HITT plate, resulting in soldering and brazing at a high temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid IC substrate on which a semiconductor chip is mounted. More specifically, the present invention relates to a hybrid IC substrate that uses an aluminum plate and is excellent in heat dissipation and suitable for high power.

[0002]

2. Description of the Related Art With the recent miniaturization and higher performance of electronic equipment and an increase in the amount of heat generated per unit volume, there has been an increasing demand for a hybrid IC substrate with high heat dissipation. Conventionally,
As a hybrid IC substrate of this type, an insulating high thermal conductive substrate in which a copper foil is adhered to the surface of an aluminum plate via an insulating layer is known (Kato et al .: Practical Surface Technology, No. 4,
55 (1982)). This substrate is called a trade name "Denka HITT plate" (Denki Kagaku Kogyo Co., Ltd.), and an epoxy adhesive highly filled with an inorganic filler having a high thermal conductivity is used for this insulating layer. The thermal conductivity of this epoxy adhesive is 4.2 × 10 ⁻³ cal / cm · sec · ° C., which is about 10 times that of ordinary epoxy resin and about 6 times that of glass epoxy. The HITT plate having the insulating layer having a thickness of about 80 μm has a thermal resistance of 0.72 ° C./W, which is about 65%.
The thermal resistance of the alumina substrate having a thickness of 0 μm is smaller than 1.02 ° C./W, and the thermal conductivity of the HITT plate is excellent.

[0003]

However, although the above-mentioned conventional hybrid IC substrate is excellent in thermal conductivity or heat dissipation, there is a problem that the insulating property is not high because the insulating layer is a thin layer. . In order to improve this insulation characteristic,
When the insulating layer is thickened, the thermal resistance of the epoxy resin is relatively large, and thus the thermal resistance of the substrate becomes large. In addition, a substrate using an epoxy resin for the insulating layer has poor heat resistance and has a drawback that high-temperature soldering or brazing cannot be performed. An object of the present invention is to provide a hybrid IC substrate which is excellent not only in heat dissipation but also in insulation and heat resistance.

[0004]

In order to achieve the above object, as shown in FIG. 1, a first hybrid I of the present invention is provided.
In the C substrate 10, the first heat-dissipating ceramic substrate 11, the aluminum plate 21, and the second heat-dissipating ceramic substrate 22 are laminated and adhered in this order through Al-Si based brazing filler metal. The thin film circuit or the thick film circuit 12 is formed on the surface of the.

Further, as shown in FIG. 2, the second hybrid IC substrate 20 of the present invention is the first hybrid IC substrate.
The heat radiation fins 31 are bonded to the back surface of the second heat radiation ceramic substrate 22 of the power supply substrate 10.

Further, as shown in FIGS. 3 and 4, the third hybrid IC substrate 30 of the present invention has a thin film circuit or a thick film circuit 1 in the central portion of the surface of the first heat dissipation ceramic substrate 11.
2 is formed, and a frame plate 32 made of aluminum is adhered to the peripheral edge of the surface of the heat dissipation ceramic substrate 11 via an Al-Si brazing material so as to be electrically insulated from the thin film circuit or the thick film circuit 12. An aluminum plate 21 is adhered to the entire back surface of the heat dissipation ceramic substrate 11 via an Al-Si based brazing material.

The first heat radiation ceramic substrate 11 is used.
Alternatively, as the second heat dissipating ceramic substrate 22, Al ₂ O _{3 is used.}
A substrate, AlN substrate or SiC substrate can be used. As shown in FIG. 5, when the first and second heat-dissipating ceramic substrates are AlN substrates 41 and 51, respectively, the substrates are oxidized to impart chemical stability to the substrates, and Al ₂ O _{3 is} applied to the substrate surfaces. After forming layers 42 and 52, it is necessary to coat SiO ₂ layers 43 and 53, respectively. It is necessary to form the Al ₂ O ₃ layer and the SiO ₂ layer because
If a thick film is formed directly on the N substrate, the glass and AlN contained in the thick film when baked in the air after the thick film is formed.
This is to solve the problem that (aluminum nitride) reacts with each other to generate N ₂ and NO gas, thereby causing bubbles in the thick film. The first or second ceramic substrate for heat dissipation has a thickness of 0.1 to 1.0 mm, the aluminum plate has a thickness of 0.1 to 1.0 mm, and the aluminum plate has a thickness of 1 to 10 of the thickness of the second ceramic substrate for heat dissipation
It is preferably 0%. Ceramic substrate is 0.1m
When it is less than m, the insulating property and mechanical strength are poor, and when the aluminum plate becomes relatively thicker than the ceramic substrate,
Cracks and fractures tend to occur during stress relaxation after adhesion. Whether the thickness of the aluminum plate is less than 0.1 mm,
Alternatively, if it is less than 10% of the ceramic substrate, the heat dissipation as a hybrid IC substrate is insufficient.

[0008]

As shown in FIG. 1, by bonding the ceramic substrates 11 and 22 with the aluminum plate 21 sandwiched therebetween, if the ceramic substrate is an Al ₂ O ₃ substrate, the thermal conductivity is 70 × 10 ^−3. An insulating layer made of an Al ₂ O ₃ substrate of cal / cm · sec · ° C. is obtained, and the thermal conductivity of this insulating layer is
The thermal conductivity of the epoxy adhesive that is the insulating layer of the conventional HITT plate is 4.2 × 10 ⁻³ cal / cm · sec ·
Much larger than ℃. When AlN or SiC whose thermal conductivity is much higher than that of Al ₂ O ₃ is used for the ceramic substrate, the thermal conductivity of the insulating layer of the present invention is further increased, and when it is used together with the aluminum plate, its thermal conductivity is further improved. As a result, the thermal resistance of the hybrid IC substrate becomes small. Further, according to the present invention, Al ₂ O ₃ , AlN or S
The ceramic substrate made of iC or the like is superior in insulating property and heat resistance to the insulating layer of the conventional HITT plate, and can be soldered or brazed at high temperature.

As shown in FIG. 2, the aluminum plate 21 and the radiation fins 3 are provided on the back surface of the second radiation ceramic substrate 22.
By bonding 1 to each other, the heat dissipation is further enhanced.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. Example 1 Al ₂ O ₃ is 96% pure and has a thickness of 0.38 m.
The Au paste was screen-printed on the surface of an Al ₂ O ₃ substrate of m, vertical 50 mm, and horizontal 50 mm, dried at 150 ° C., and then fired in the atmosphere at 850 ° C. for 10 minutes using a continuous belt furnace. Then, a RuO ₂ type thick film resistor paste is printed, dried at 150 ° C., and again at 850 ° C. in the atmosphere at 10 ° C.
It was baked for a minute to obtain a thick film circuit board. Next, this substrate, a pure aluminum plate having the same shape and the same size as this substrate and a thickness of 0.15 mm, and Al ₂ O ₃ having the same shape and the same size as this aluminum plate are 96%.
Between the Al ₂ O ₃ substrate having a thickness of 0.38mm of purity, overlapping them across these same shape and size thickness 30μm of the Al-7.5% Si foil respectively, these 2 kgf / cm ²
Was applied and heated in a vacuum furnace at 630 ° C. for 30 minutes to laminate and adhere the three plates. As shown in FIG. 1, as a result, an aluminum plate 21 as a high thermal conductive layer is adhered between the Al ₂ O ₃ substrate 11 and the Al ₂ O ₃ substrate 22, and a thick film resistor 12a is provided on the surface of the substrate 11. The substrate 10 for hybrid IC on which the film circuit 12 was formed was obtained. here,
The Al ₂ O ₃ substrate 22 is bonded to prevent warpage of the Al ₂ O ₃ substrate 11 caused by bonding the aluminum plate 21 and to balance the stress. The silicon semiconductor chip 14 was mounted on the thick film circuit 12 of the substrate 10 by die bonding at 420 ° C. using Al—Si solder and further by Au wire bonding at 300 ° C. in order to further investigate the heat dissipation characteristics.

[0011] <Example _2> Al 2 O ₃ is 96% pure thickness 0.38 mm, vertical 50mm, horizontal 50mm of Al ₂ O ₃
A thick paste was printed and dried on the surface of the substrate in the same manner as in Example 1, and a RuO ₂ -based thick film resistor paste was printed, dried and fired to obtain a thick film circuit board. Next, this board and the same shape and size as this board, thickness of 0.15 mm
Pure aluminum plate and Al ₂ O _{3 of the} same shape and size as the aluminum plate of 96% purity and a thickness of 0.38 mm of Al ₂ O ₃
Between the substrates, Al-having the same shape and size and a thickness of 30 μm
These were stacked with a 7.5% Si foil sandwiched therebetween. At this time, a through hole having an inner diameter of 0.8 mm was formed by laser processing or the like in the Al ₂ O ₃ substrate on the side where the thick film circuit was not formed, and the Al wire was inserted therein.
60 μm thick Al-7.5% S between the Al ₂ O ₃ substrate which is adhered and on which the thick film circuit is not formed and the radiation fin.
i foil was sandwiched, a load of 20 g / cm ² was applied, and the foil was heated in a vacuum furnace at 630 ° C. for 30 minutes and inserted into the through hole A
The 1-wire and the radiation fin were bonded. That is, the radiating fins were connected to the aluminum plate via thermal via holes. As shown in FIG. 2, this results in Al ₂
An aluminum plate 21 as a high thermal conductive layer is adhered between the O ₃ substrate 11 and the Al ₂ O ₃ substrate 22, a thick film circuit 12 having a thick film resistor 12a is formed on the surface of the substrate 11, and a thermal via 22a is formed. Thus, the hybrid IC substrate 20 in which the radiation fin 31 is bonded to the substrate 22 was obtained. The same silicon semiconductor chip 14 as in Example 1 was further mounted on the thick film circuit 12 of the substrate 20 in the same manner as in Example 1.

[0012] <Example _3> Al ₂ O 3 96% purity thickness 0.635 mm, longitudinal 50 mm, lateral 50 mm Al ₂
Screen-print Au paste on the surface of O ₃ substrate 15
After drying at 0 ° C., Au paste was filled in the through holes formed in the Al ₂ O ₃ substrate and dried at 150 ° C. Then, in a continuous atmosphere using a continuous belt furnace at 850 ° C for 1
Bake for 0 minutes. Next, a RuO ₂ type thick film resistor paste is printed, dried at 150 ° C., and again in air at 850 ° C.
And baked for 10 minutes to obtain a thick film circuit board. Next, this substrate and a pure aluminum plate having the same shape and size and a thickness of 0.2 mm and having a thickness of 30 μm of Al-7.5% Si foil sandwiched between them were stacked, and 2 kgf / cm ² A load was applied and heating was performed in a vacuum furnace at 630 ° C. for 30 minutes to bond the two plates. An Al-7.5% Si foil having a thickness of 30 μm is sandwiched between the surface end of the Al ₂ O ₃ substrate and a plurality of lead terminals made of aluminum and having a thickness of 0.4 μm, and the lead terminals are further stacked. A pure aluminum frame plate having a thickness of 0.4 μm is arranged on the surface end portion of an Al ₂ O ₃ substrate not provided with Al ₇ O having a thickness of 30 μm between the surface end portion of the substrate and the frame plate.
These are stacked with 5% Si foil sandwiched between them, and a load of ² kgf / cm ² is applied to the lead terminal, the frame plate and the surface end portion, and the mixture is heated in a vacuum furnace at 630 ° C. for 30 minutes to form the lead terminal and the frame plate on the substrate. Glued to the edge of the surface. As shown in FIGS. 3 and 4, by this, the aluminum plate 21 as the high thermal conductive layer and the ground layer is bonded to the back surface of the Al ₂ O ₃ substrate 11,
Thick film circuit 1 having thick film resistor 12a on the surface of substrate 11
2 was formed, and the hybrid IC substrate 30 was obtained in which the plurality of lead terminals 13 and the frame plate 32 were adhered to the end portions of the surface of the substrate 11. Here, the frame plate 32 is the Al ₂ O ₃ substrate 11
The aluminum plate 21 is adhered in order to prevent the warp of the substrate caused by the adhesion and to balance the stress. Further, the same silicon semiconductor chip 14 as in Example 1 was mounted on the thick film circuit 12 of the substrate 30 in the same manner as in Example 1. As shown in FIG. 4, a through hole 11a filled with Au is provided in the substrate 11 immediately below the semiconductor chip 14, and the ground circuit 12b of the semiconductor chip 14 is electrically connected to the aluminum plate 21 through the through hole 11a. Was done.

<Embodiment 4> Same shape, same size and thickness of 0.38 m
Two AlN substrates having a length of 50 mm and a width of 50 mm were heat-treated in an oxygen atmosphere at 1300 ° C. for 1 hour to form Al ₂ O ₃ layers as oxide layers on both front and back surfaces of each substrate. Next, SiO ₂ sol is applied to the entire front surface of one AlN substrate where the thin film circuit is formed and the entire back surface of the other AlN substrate where the thin film circuit is not formed, and then both AlN substrates are dried at 300 ° C. for 1 hour, and subsequently, By firing at 900 ° C. for 1 hour, a SiO ₂ layer was formed on the front surface of one AlN substrate and the entire back surface of the other AlN substrate. Next, this one AlN substrate, a pure aluminum plate of the same shape and size and a thickness of 0.15 mm, and the other A
These are laminated with an Al-7.5% Si foil of the same shape and size and a thickness of 30 μm sandwiched between them and the 1N substrate,
A load of ² kgf / cm ² is applied to these, and 6 in a vacuum furnace
The plates were laminated and adhered by heating at 30 ° C. for 30 minutes. As shown in FIG. 5, as a result, the aluminum plate 21 as the high thermal conductive layer was bonded between the AlN substrate 41 and the AlN substrate 51. A Cu thin film is formed on the entire surface of the adhered AlN substrate 41 by a sputtering method, and a mask for covering the circuit pattern portion is used as a mask, followed by etching with an aqueous solution of ferric chloride to dissolve the Cu thin film in the portion not covered by the mask. Then, a thin film circuit 44 was formed by forming a conductor pattern on the surface of the AlN substrate 41 and similarly forming a Ni—Cr thin film resistor 44a. Here, the AlN substrate 51 is an Al produced by bonding the aluminum plate 21.
The N substrate 41 is adhered in order to prevent the warp and to balance the stress. The thin film circuit 44 of the hybrid IC substrate 40 further includes the same silicon semiconductor chip 1 as in the first embodiment.
Implemented 4.

<Comparative Example 1> Aluminum plate 21 and Al ₂
The same silicon semiconductor chip 14 as in Example 1 was mounted on the circuit of the hybrid IC substrate having only the Al ₂ O ₃ substrate 11 except that the O ₃ substrate 22 was not adhered.

<Comparative Example 2> Thickness 0.83 mm, vertical 50
8 mm thick, 50 mm wide, pure aluminum plate
C with a thickness of 35 μm through a 0 μm epoxy adhesive layer
Substrate for hybrid IC with u foil bonded
A substrate equivalent to a TT plate) was prepared. This epoxy adhesive is prepared by highly filling an inorganic filler having high thermal conductivity. The same silicon semiconductor chip 14 as in Example 1 was further mounted on the circuit of the hybrid IC substrate.

<Comparative Test and Evaluation> (a) Heat Dissipation Test Each of the hybrid IC substrates of Examples 1 to 4 and the hybrid IC substrates of Comparative Examples 1 and 2 in a thermostatic chamber at 25 ° C. Then, the surface temperature T _C1 of the chip and the amount of heat generation Q ₁ of the chip were measured after 20 minutes of application of electricity. The room temperature as T _R1, determine the heat radiation characteristics by the following equation (1). Heat dissipation characteristic (° C./W)=(T _C1 −T _R1 ) / Q ₁ (1) The hybrid IC substrates of Examples 1 to 4 and the hybrid IC substrates of Comparative Examples 1 and 2 are chipped. 30m thickness water-cooled at 20 ℃ with the mounting surface facing upward
It was placed on a pure Cu plate of a so-called ideal radiator of m, vertical 100 mm, and horizontal 100 mm. The silicon semiconductor chip is energized in the same manner as above, and the surface temperature T of the chip after 10 minutes
_C2 and the calorific values were measured Q _2. The temperature of the substrate back surface T _R2
As a result, the thermal resistance value of the substrate was obtained from the following equation (2). In the hybrid IC substrate 20 of Example 2, the heat radiation fin 31 was removed and the measurement was performed. The thermal resistance of the substrate (℃ / W) = (T C2 -T R2) / Q 2 ...... (2) These results are shown in Table 1.

[0017]

[Table 1]

As is clear from Table 1, Examples 1 to 4 were superior to Comparative Example 1 in both heat dissipation characteristics and substrate thermal resistance. Further, as to the heat dissipation characteristics, the second and the fourth embodiments are superior to the second comparative example, and the first and the third examples show the same value. Regarding the thermal resistance value of the substrate, all of Examples 1 to 4 were superior to Comparative Example 2. Particularly, the thermal resistance value of Example 4 was about one-third that of Comparative Example 2.

(B) Insulation test and heat resistance test The dielectric strength and heat resistance of the hybrid IC substrates of Examples 1 to 4 and the hybrid IC substrate of Comparative Example 2 were examined. As the withstand voltage, the maximum voltage that does not cause dielectric breakdown was measured when a current value of 1 mA or less was applied between the circuit on the front surface of the hybrid IC substrate and the back surface of the substrate for 1 minute. Regarding the heat resistance, the presence or absence of swelling of the circuit on the surface of the substrate and undulation of the substrate when the substrate for hybrid IC was kept at 260 ° C. and 430 ° C. for 5 minutes respectively was examined visually. Table 2 shows the results. In the results of heat resistance in Table 2, ◯ means good without any change, and x means bad such as swelling or waviness.

[0020]

[Table 2]

As is clear from Table 2, the withstand voltage of Comparative Example 2 is 2 kV or less, while that of Examples 1 to 4 is 5 kV or more. Further, at 430 ° C., Comparative Example 2 produced swelling and undulation, whereas Examples 1 to 4
No abnormalities were found.

The heat-dissipating ceramic substrate of the present invention is A
Not limited to the l ₂ O ₃ substrate and the AlN substrate, a SiC substrate may be used. The AlN substrate may be used as the second and third hybrid IC substrates as in Example 4, and a thin film circuit may be formed on the surface of the first heat radiation ceramic substrate instead of the thick film circuit. Further, as an Al-Si brazing material,
Although Al-7.5% Si foil was illustrated, other than this, Al-
13% Si, Al-9.5% Si-1.0% Mg, Al
A foil made of -7.5% Si-10% Ge or the like can also be used.

[0023]

As described above, the hybrid IC substrate of the present invention has a heat dissipation property that forms a circuit of an aluminum plate, as compared with the hybrid IC substrate made of an insulating and high thermal conductive substrate represented by a conventional HITT plate. By adhering to the back surface of the ceramic substrate, heat dissipation can be improved. Particularly, by adhering the aluminum plate and the heat radiation fins to the back surface of the second heat radiation ceramic substrate, the heat radiation is further enhanced. Further, according to the present invention, Al ₂ O ₃ , AlN or S
The ceramic substrate made of iC or the like is superior in insulating property and heat resistance to the insulating layer of the conventional HITT plate, and can be soldered or brazed at high temperature.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first hybrid IC substrate of the present invention.

FIG. 2 is a sectional view of a second hybrid IC substrate of the present invention.

FIG. 3 is a cross-sectional view of a third hybrid IC substrate of the present invention.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a cross-sectional view of another first hybrid IC substrate of the present invention.

[Explanation of symbols]

10, 20, 30, 40 Hybrid IC substrate 11 First heat dissipation ceramic substrate (Al ₂ O ₃ substrate) 11a Through hole 12 Thick film circuit 12b Ground circuit 13 Lead terminal 21 Aluminum plate 22 Second heat dissipation ceramic substrate (Al ₂ O ₃ substrate) 22a thermal via 31 heat dissipation fin 32 frame plate 41 first heat dissipation ceramic substrate (AlN substrate) 51 second heat dissipation ceramic substrate (AlN substrate) 42, 52 oxide layer (Al ₂ O ₃ layer) 43, 53 SiO ₂ layer

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location H01L 23/36 H05K 1/02 F 1/05 Z H01L 23/12 J 23/14 M 23/36 Z

Claims (7)

[Claims] 1. A first heat dissipation ceramic substrate (11, 41), an aluminum plate (21), and a second heat dissipation ceramic substrate (22, 51).
Are laminated and adhered in this order via Al-Si type brazing filler metal, and a thin film circuit (44) or a thick film circuit (12) is formed on the surface of the first heat dissipation ceramic substrate (11, 41). IC
Substrate. 2. A first heat dissipation ceramic substrate (11, 41), an aluminum plate (21), and a second heat dissipation ceramic substrate (22, 51).
Are laminated and adhered in this order through Al-Si brazing filler metal, and a thin film circuit (44) or a thick film circuit (12) is formed on the surface of the first heat dissipation ceramic substrate (11, 41), and A hybrid IC substrate in which a heat radiation fin (31) is adhered to the back surface of the second heat radiation ceramic substrate (22, 51). 3. A thin film circuit (44) or a thick film circuit (12) is formed in the central portion of the surface of the first heat dissipation ceramic substrate (11, 41), and the thin film circuit (44) or the thick film circuit (12). A frame plate (32) made of aluminum is adhered to the peripheral edge portion of the surface of the heat dissipation ceramic substrate (11, 41) via an Al-Si brazing material so as to be electrically insulated from the heat dissipation ceramic substrate ( A hybrid IC substrate in which an aluminum plate (21) is adhered to the entire back surface of (11, 41) via an Al-Si brazing material. 4. The earth circuit (12b) and the aluminum plate (21) of the thin film circuit (44) or the thick film circuit (12) formed in the central portion of the surface of the first heat dissipating ceramic substrate (11, 41). The substrate for hybrid IC according to claim 3, wherein a through hole (11a) for electrically connecting and is formed in the heat dissipation ceramic substrate (11, 41). 5. The first heat dissipation ceramic substrate (11, 41) is A
l ₂ O ₃ substrate, a substrate for a hybrid IC of a SiC substrate or substrate oxidation treatment after the substrate surface according with claim 1, which is a AlN substrate coated with the SiO ₂ layer 4. 6. The first and second heat radiation ceramic substrates (11,
41, 22, 51) are Al ₂ O ₃ substrates, SiC substrates, or Al whose surfaces are coated with a SiO ₂ layer after the substrate is oxidized.
The hybrid IC substrate according to claim 1, which is an N substrate. 7. The first or second heat radiation ceramic substrate (11,
41,22,51) has a thickness of 0.1 to 1.0 mm, the aluminum plate (21) has a thickness of 0.1 to 1.0 mm,
The hybrid IC substrate according to any one of claims 1 to 4, wherein the thickness of the aluminum plate is 10 to 100% of the thickness of the first or second ceramic substrate for heat dissipation.