JP3139523B2 - Radiation fin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiating fin for dissipating heat generated from a silicon semiconductor chip mounted on a ceramic circuit board to the atmosphere.

[0002]

2. Description of the Related Art Heretofore, as a heat radiation fin of this kind, a fin body formed by cutting a high thermal conductive ceramic such as aluminum nitride (hereinafter, referred to as AlN) is attached to a silicon semiconductor chip or a ceramic substrate with an adhesive. Bonded ones are known. In this radiating fin, since the fin main body and the semiconductor chip or the ceramic substrate have the same coefficient of thermal expansion, even if heat is applied to the semiconductor chip or the ceramic substrate and the fin main body, no warping occurs.

[0003]

However, in the conventional radiating fins described above, since the fin main body is formed by cutting hard and brittle AlN, the number of processing steps of the fin main body is increased and the manufacturing cost is increased. There was a possibility that the fin body might be chipped by a relatively small impact. In addition, since the heat conductivity of the above-described conventional radiating fin is relatively small, there is a problem that the radiating characteristic of the fin body is not very good. Furthermore,
When the fin body is bonded to the silicon semiconductor chip or the ceramic substrate via solder with the above-described conventional radiating fins, it is necessary to perform a metallizing process on the bonding surface in advance,
This caused the deformation of the fin body.

An object of the present invention is to provide a heat radiation fin that can absorb thermal deformation and prevent warpage, reduce the number of processing steps of the fin body, and is not easily damaged by an impact. Another object of the present invention is to provide a heat radiation fin that can improve heat radiation characteristics and can be adhered even after a semiconductor chip is mounted on a ceramic circuit board.

[0005]

[0006]

Means for Solving the Problems According to claim 1 of the present invention.
The present invention is a radiation fin 11 directly bonded to the outer surface of a chip 12 mounted on a ceramic circuit board 13 via solder or an adhesive as shown in FIG. 3, and has an area capable of covering the outer surface of the chip 12. A first metal layer 21 made of an aluminum material, a ceramic substrate 18 having an area capable of covering the first metal layer 21, a second metal layer 22 made of an aluminum material having an area capable of covering the ceramic substrate 18, The fin body 19 made of an aluminum material having an area capable of covering the two metal layers 22 is laminated and bonded in this order via an Al-based brazing material. According to a second aspect of the present invention, there is provided a heat radiation fin directly bonded to an outer surface of a chip mounted on a ceramic circuit board via a solder or an adhesive, the aluminum material having an area capable of covering the outer surface of the chip. A first metal layer comprising:
A ceramic substrate having an area capable of covering the first metal layer and a fin body made of an aluminum material having an area capable of covering the ceramic substrate are laminated and bonded in this order via an Al-based brazing material.

[0007] The invention according to claim 3 is based on claim 1 or
Is an invention according to 2, further chip ceramic board
Et provided with through holes for a plurality of heat conduction in a position opposed to
Is characterized in that the aluminum material is filled their <br/> respectively to a plurality of heat conduction Suruho Le. Claim 4 of the present invention
According to the invention according to the present invention, as shown in FIG.
Solder or contact the back of the mounted ceramic circuit board 13
A radiation fin 11 directly adhered via an adhesive,
It has an area that can cover the back surface of the ceramic circuit board 13
A first metal layer 21 made of aluminum material and a first metal
Ceramic substrate 18 having an area capable of covering layer 21
And an area having an area capable of covering the ceramic substrate 18.
A second metal layer 22 made of a minium material;
Of aluminum material with an area that can cover
And the main body 19 in this order via the Al-based brazing material.
Laminated and opposed to the chip 12 of the ceramic substrate 18
Are provided with a plurality of through holes 111 for heat conduction.
And a plurality of heat conduction through holes 111
It is characterized in that each of the materials 112 is filled. Claim
Item 5 relates to a ceramic having a chip mounted on the surface.
Directly bonded to the back of the circuit board via solder or adhesive
Radiating fins,
First gold made of aluminum material having an area that can be covered
A ceramic having an area capable of covering the metal layer and the first metal layer.
With an area that can cover the ceramic substrate and the ceramic substrate.
The fin body made of Luminium material is an Al filter
Laminated in this order via the filler material,
Multiple heat conduction through holes at the position facing the chip
Aluminum heat transfer through holes
It is characterized by being filled with materials. FIG.
As shown in FIG. 3, the thickness of the second metal layer 22 is preferably not more than ／ of the thickness of the first metal layer 21. Further, as shown in FIG. 5, the fin body 99 is a corrugated fin having a ridge 99a, and it is preferable that the fin body 99 is divided into a plurality by cutting in a direction orthogonal to the ridge 99a.

[0008]

In the heat radiation fin shown in FIG. 3 , the heat generated from the chip 12 spreads directly over the entire surface of the first metal layer 21 having a high thermal conductivity, and the second heat fin has a high thermal conductivity via the ceramic substrate 18. Transmitted to the metal layer 22, further spread over the entire surface in the second metal layer 22 and transmitted to the fin body 19,
Ru is dissipated to the atmosphere from the fin body 19.

[0009]

Next, a first embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the radiation fins 11 are directly bonded to the back surface of a thin-film multilayer ceramic circuit board 13 on which a silicon semiconductor chip 12 is mounted via an adhesive. The ceramic circuit board 13 includes a plurality of Al ₂ O ₃ substrates 1
4 and a plurality of tungsten conductors 16 forming a circuit
It is formed by simultaneous firing at a high temperature of about 600 ° C. and laminating and bonding. After the semiconductor chip 12 is die-bonded on the surface of the ceramic circuit board 13 at 420 ° C. using Al—Si solder, the Au wire 17 is formed at 300 ° C.
And is implemented by performing wire bonding. In this example, three semiconductor chips 12 are mounted on the surface of the ceramic circuit board 13 at predetermined intervals. These semiconductor chips 12 form a square having a side of 33 mm.

The radiating fins 11 are formed on a ceramic circuit board 13.
Three first metal layers 21 which are disposed at positions facing the semiconductor chip 12 on the back surface of the semiconductor chip 12 and have an area capable of covering the back surface of the ceramic circuit board 13, and which can cover the three first metal layers 21, respectively. Ceramic substrates 18 having different areas, three second metal layers 22 having an area capable of covering the three ceramic substrates 18, and three second metal layers 22
And three fin bodies 19 having an area capable of covering the fin body 19. The first and second metal layers 21 and 22 are formed of an aluminum alloy containing 97% or more of aluminum, and the ceramic substrate 18 is formed of Al ₂ O _{3 in} this example. The first metal layer 21, the second metal layer 22, and the ceramic substrate 18 form a square having a side of 40 mm.
The thicknesses of the first, second metal layers 22 and the ceramic substrate 18 are 0.4 mm, 0.2 mm and 0.635 mm, respectively.

The ceramic substrate 18 is provided on the first metal layer 21.
Is placed with a 30 μm thick Al-7.5% Si foil (weight%, the same applies hereinafter). A second metal layer 22 is formed on the ceramic substrate 18 with a 30 μm thick Al-7.5% Si foil.
Placed on top of a foil, and in this state, 2kgf / c
By applying a load of m ² and heating at 630 ° C. for 30 minutes in a vacuum furnace, the first metal layer 21, the ceramic substrate 18 and the second metal layer 22 are laminated and bonded.

As shown in FIGS. 1 and 2, the fin body 19 has a plurality of first fins provided at predetermined intervals in the lateral direction.
A projection 19a, a first projection 19 connected to the first projection 19a,
a, a plurality of second protrusions 19b provided in the lateral direction with a predetermined distance from the first protrusion 19a, and first and second protrusions 19a, 19b.
It is an aluminum corrugated louver fin having a window 19c formed therebetween. The first projections 19a and the second projections 19b are alternately provided in the vertical direction. Fin body 19
Is formed by pressing an aluminum alloy plate containing 87% or more of aluminum having a thickness of 0.3 mm, its length and width are substantially the same as those of the metal layers 21 and 22, and its height is 6 mm. . The second laminated and bonded
On the metal layer 22, the fin body 19 is made of 60 μm Al-
In this state, a load of 20 g / cm ² is applied to these at a temperature of 630 ° C. in a vacuum furnace.
By heating for 0 minutes, the fin body 19 is adhered to the second metal layer 22 to form the radiation fin 11. 3 above
The heat dissipating fins 19 are bonded to the first metal layer 21 such that the first metal layer 21 is located on the back surface of the ceramic circuit board 13, that is, on the back surface of the lowermost Al ₂ O ₃ substrate 14, directly below the three semiconductor chips 12. Is bonded directly to the ceramic circuit board 13 by bonding with an epoxy resin.

The operation of the radiation fin thus configured will be described. The heat generated from the silicon semiconductor chip 12 spreads over the entire surface of the first metal layer 21 having a high thermal conductivity via the thin-film multilayer ceramic circuit board 13 and the second metal having a high thermal conductivity via the ceramic substrate 18. Transfer to layer 22. This heat further spreads over the entire surface in the second metal layer 22 and is transmitted to the fin body 19, and the fin body 19
From the air to the atmosphere. As a result, the temperature rise of the semiconductor chip 12 can be suppressed low. Although the ceramic circuit board 13 and the fin body 19 have different coefficients of thermal expansion, the first and second metal layers 21 and 22 having low deformation resistance are bonded to both surfaces of the ceramic substrate 18 and the thermal expansion of the ceramic substrate 18 is improved. Since the coefficient is substantially the same as that of the ceramic circuit board 13, peeling due to thermal cycling on the bonding surface can be prevented even when bonding is performed with an adhesive.

FIG. 3 shows a second embodiment of the present invention. 3, the same reference numerals as those in FIG. 1 indicate the same parts. In this example,
The radiation fins 11 are directly bonded to the outer surface of the silicon semiconductor chip 12 mounted on the thin-film multilayer ceramic circuit board 13 formed in the same manner as in the first embodiment via solder. The semiconductor chip 12 is mounted on the surface of the ceramic circuit board 13 via solder bumps 51. The solder bumps 51 are formed by projecting solder on the electrodes on the surface of the semiconductor chip 12 in a protruding manner, and are formed by a Cu ball plated with a composite plating of Ni and Au or by an alloy of Pb and Sn. The solder bumps 51 raised on the electrodes of the semiconductor chip 12 are temporarily fixed to the terminals of the tungsten conductors 16 of the ceramic circuit board 13 by the adhesive force of the flux, and the solder bumps 51 are melted by heating in this state. The chip 12 is a ceramic circuit board 13
Implemented in The semiconductor chip 12 forms a square having a side of 33 mm.

The radiating fins 19 have a first metal layer 21 having an area capable of covering the outer surface of the semiconductor chip 12 and a ceramic substrate 18 having an area capable of covering the first metal layer 21.
And a second having an area capable of covering the ceramic substrate 18.
The fin body includes a metal layer and a fin body having an area capable of covering the second metal layer. The first metal layer 21, the second metal layer 22, and the ceramic substrate 18 are formed of the same material and have the same dimensions as the first metal layer, the second metal layer, and the ceramic substrate of the first embodiment. The second metal layer 22 and the ceramic substrate 18 are laminated and bonded in the same manner as the first metal layer, the second metal layer, and the ceramic substrate of the first embodiment.

The fin body 19 is a corrugated louver fin formed of the same material and in the same shape as in the first embodiment, and the fin body 19 is formed by laminating and bonding the second metal layer 22 in the same manner as in the first embodiment. The heat radiation fins 11 are formed by being bonded on the fins. The surface of the radiating fins 19 that is bonded to the outer surface of the semiconductor chip 12 via solder, that is, the back surface of the first metal layer 21 is pre-plated with Ni, and the outer surface of the semiconductor chip 12 is back surface such as Ni metallized. Processing is performed. The radiating fins 19 are placed on the outer surface of the semiconductor chip 12 via a Sn-3.5% Ag solder foil having a thickness of 50 to 100 μm. In this state, a load of 10 g / cm ² is applied, and the radiating fins 19 are heated at 260 ° C. By heating for 1 to 3 minutes, the semiconductor chip 12 is directly bonded to the outer surface.

The operation of the radiation fin thus configured is the same as that of the first embodiment except that the heat generated from the silicon semiconductor chip 12 directly spreads over the entire surface in the first metal layer 21 having a high thermal conductivity. Since it is the same, a repeated description is omitted.

In the first and second embodiments, the fin body includes a first projection, a second projection provided laterally shifted from the first projection, and a window formed between the first and second projections. Although the aluminum corrugated louver fins having the above-mentioned structure are mentioned, the fin body 79 may be an aluminum corrugated honeycomb fin having a substantially honeycomb shape as shown in FIG. A plurality of ridges 99a extending in the vertical direction at predetermined intervals
And aluminum corrugated fins having openings 99b formed at both ends of the ridges 99a.
When the fin body 99 is bonded to the ceramic substrate of FIG. 1 via the second metal layer, the fin body 9 is cut into a plurality of sections by cutting in a direction perpendicular to the ridges 99a.
This is preferable because warpage caused by a difference in the coefficient of thermal expansion when the substrate 9 is bonded to the ceramic substrate can be reduced.
Although not shown, the fin body may be an aluminum pin fin having a large number of pins projecting from the mounting plate.

As shown in FIG. 6, a plurality of through holes 111 for heat conduction are provided at positions facing the chips 12 of the ceramic substrate 18 of the first embodiment, and these through holes 111 are filled with an aluminum material 112, respectively. May be. In this case, the heat of the first metal layer 21 can be transmitted to the second metal layer 22 more smoothly through the aluminum material 112. Although not shown, a through hole for heat conduction filled with an aluminum material may be provided in the ceramic substrate 18 of the second embodiment. In the first embodiment, the radiation fins are directly adhered to the ceramic circuit board with an epoxy-based adhesive.
It may be bonded directly via 3.5% Ag solder. In the second embodiment, the radiation fins have a thickness of 50 to 100.
Although it was directly bonded to the outer surface of the silicon semiconductor chip via the Sn-3.5% Ag solder foil of μm, it may be directly bonded via a paste-like cream solder, or directly by an epoxy-based adhesive. You may. In the first and second embodiments, the ceramic substrate located between the first and second metal layers is made of Al ₂ O _3. However, this is an example, and the ceramic substrate is made of AlN or SiC. It may be formed.

In the first and second embodiments, the thicknesses of the first metal layer, the second metal layer and the ceramic substrate are 0.4 mm, 0.2 mm and 0.635 mm, respectively. The thickness of the layer may be in the range of 0.1 to 1.0 mm, and the thickness of the second metal layer is two times the thickness of the first metal layer.
/ 3 or less and within a range of 0 to 0.5 mm, and the thickness of the ceramic substrate is 1 to the thickness of the first metal layer.
It is sufficient that it is 10 to 10 times and within the range of 0.1 to 1.0 mm. Therefore, as shown in FIG. 7, the fin body 19 is directly formed on the back surface of the ceramic substrate 18 without using the second metal layer.
It may be bonded via a brazing filler metal. In this case, the bonding portion of the fin body 19 to the ceramic substrate 18 plays the role of the second metal layer. The reason for limiting the thickness as described above is that
When the thickness of the metal layer is less than 0.1 mm, the heat generated from the chip is not sufficiently dissipated, and when the thickness of the first and second metal layers exceeds 1.0 mm and 0.5 mm, respectively, the bonding is performed. This is because cracks and cracks are likely to occur when the stress is relaxed later. If the thickness of the ceramic substrate is less than 0.1 mm, the insulating properties and mechanical strength are inferior. If the thickness exceeds 1.0 mm, the thermal resistance of Al ₂ O ₃ increases. However, this is not the case when AlN or SiC, which is a ceramic having high thermal conductivity equivalent to aluminum, is used. Further, in the first and second embodiments, the Al-7.5% Si foil is exemplified as the Al-based brazing material, but in addition to this, Al-13% Si, Al-9.5% Si foil is used.
A foil made of -1.0% Mg, Al-7.5% Si-10% Ge, or the like can also be used.

[0021]

As described above, according to the present invention, the cell
The first metal layer made of aluminum material, the ceramic substrate, the second metal layer made of aluminum material, and the fin body were laminated and bonded in this order to the outer surface of the chip mounted on the lamic circuit board via an Al-based brazing material. Thermal deformation due to the difference in thermal expansion coefficient between the fin body and the ceramic substrate can be absorbed by the first and second metal layers having low deformation resistance.
You. Also, in comparison with a conventional heat dissipating fin having a fin body made of AlN, the present invention can reduce the number of processing steps of the fin body, is less likely to be damaged even when an impact is applied to the fin body, and furthermore has a heat radiation characteristic of the fin body. Can be improved.

Further, even after the semiconductor chip is mounted on the ceramic circuit board, the radiating fins can be bonded to the ceramic circuit board without melting and peeling the soldered portion of the semiconductor chip or the ceramic circuit board. Further, by providing a plurality of through holes for heat conduction at positions facing the chips on the ceramic substrate, and filling these through holes with aluminum material, heat of the first metal layer can pass through the aluminum material more smoothly through the second material. that Tsutawa the metal layer or the fin body.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a ceramic circuit board including a radiation fin according to a first embodiment of the present invention.

FIG. 2 is a view taken in the direction of arrow A in FIG.

FIG. 3 is a sectional view showing a second embodiment of the present invention and corresponding to FIG. 1;

FIG. 4 is a sectional view of a fin body showing a third embodiment of the present invention.

FIG. 5 is a sectional view showing a fourth embodiment of the present invention and corresponding to FIG. 4;

FIG. 6 is a sectional view showing a fifth embodiment of the present invention and corresponding to FIG. 1;

FIG. 7 is a sectional view showing a sixth embodiment of the present invention and corresponding to FIG. 1;

[Explanation of symbols]

 11, 79, 99 Heat radiation fins 12 Silicon semiconductor chip 13 Thin film multilayer ceramic circuit board 18 Ceramic substrate 19 Fin body 21 First metal layer 22 Second metal layer 111 Through hole for heat conduction 112 Aluminum material

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-363052 (JP, A) JP-A-57-138198 (JP, A) JP-A-62-287649 (JP, A) JP-A-5-138649 41471 (JP, A) JP-A-6-188329 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 23/36 H05K 7/20

Claims (7)

(57) [Claims] A radiating fin (11) directly bonded to an outer surface of a chip (12) mounted on a ceramic circuit board (13) via solder or an adhesive, and covering the outer surface of the chip (12). A first metal layer (21) made of an aluminum material having a possible area;
1) a ceramic substrate (18) having an area capable of covering the ceramic substrate (18), a second metal layer (22) made of an aluminum material having an area capable of covering the ceramic substrate (18), and a second metal layer (2).
A radiating fin characterized in that a fin body (19) made of an aluminum material having an area capable of covering 2) is laminated and bonded in this order via an Al-based brazing material. 2. A radiator off <br/> fin that is bonded directly via a solder or adhesive <br/> outer surface of the chip mounted on the ceramic circuit board, the outer surface of the chip a first metal layer made of aluminum material having a coatable surface area, a ceramic board having an area capable of covering the first metal layer, wherein the ceramic base plate
Radiating fins, characterized in that the fins present made of an aluminum material having an area capable coating are laminated and bonded in this order via the Al based brazing material, respectively. 3. A plurality of heat conduction Suruho Le at a position opposite to the chip of the ceramic base plate is provided, the aluminum material to the plurality of heat conduction Suruho Le is filled according to claim 1, wherein each Radiation fins. 4. A ceramic having a chip (12) mounted on its surface.
Direct connection to the back of the circuit board (13) via solder or adhesive
Radiation fins (11) to be worn, The area that can cover the back surface of the ceramic circuit board (13) is
A first metal layer (21) made of an aluminum material,
A ceramic base having an area capable of covering the first metal layer (21);
Plate (18) and the area that can cover the ceramic substrate (18)
A second metal layer (22) made of an aluminum material having
Aluminum having an area capable of covering the second metal layer (22)
The fin body (19) made of a brazing material
Laminated in this order via A position of the ceramic substrate (18) facing the chip (12).
Multiple through holes (111) for heat conduction
The aluminum through holes for multiple heat conduction holes (111) Um material
(112)
N. 5. A ceramic circuit having a chip mounted on its surface.
Directly bonded to the back of the board via solder or adhesive
Radiation fins, It has an area that can cover the back surface of the ceramic circuit board
A first metal layer made of an aluminum material, and the first metal
A ceramic substrate having an area capable of covering the layer;
Aluminum material with an area that can cover the lamic substrate
And the fin body consisting of
Laminated and bonded in this order, A plurality of ceramic substrates are provided at positions facing the chips.
A plurality of through holes for heat conduction are provided;
Aluminum material was filled in through holes for
A radiation fin characterized by the above. 6. The thickness of the second metal layer (22) is equal to that of the first metal layer (21).
The heat radiation fin according to claim 1 , wherein the thickness of the heat radiation fin is not more than ／ of the thickness of the heat radiation fin. 7. The fin body (99) is a corrugated fin having a ridge (99a), and the fin body (99) is divided into a plurality by cutting in a direction orthogonal to the ridge (99a). A heat radiation fin according to any one of claims 1 to 6.