JPH05275581A - Ceramic package - Google Patents

Abstract

PURPOSE:To provide a ceramic package having extremely excellent heat radiating characteristics with no sacrife of electric characteristics or high-density mounting property. CONSTITUTION:The package is provided with a ceramic circuit board 22, a plurality of external terminals 25 stuck to the surface of the board 22 opposite to the surface on which a semiconductor chip 26 is mounted, and an interposed material 31 for radiating heat provided on the external terminal joining-side surface of the board 22 immediately below the surface mounting the chip 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic package, and more particularly to a ceramic package having improved heat dissipation from a mounted semiconductor chip.

[0002]

2. Description of the Related Art A semiconductor device package protects a semiconductor chip, which is easily damaged mechanically, from the surrounding environment,
The first purpose is to provide mechanical protection from various stresses applied during handling of the device assembly. However, with the recent development of semiconductor technology, there is a demand for gradually increasing the electrical and thermal capabilities of the package in addition to the mechanical protection. That is, since semiconductor chips are being developed in the direction of increasing circuit scale, high heat generation, multi-pin, high speed, and large chips, package structures corresponding to them, for example, pin grid array packages, are receiving attention.

By the way, a conventional pin grid array package having a structure shown in FIG. 2 is known.
The pin grid array package 1 includes a ceramic multilayer circuit board 2. The ceramic multilayer circuit board 2 includes a base material 3 made of, for example, an AlN sintered body, wiring (not shown) formed on the front and back surfaces of the base material 3, and internal wiring formed in the base material 3. 4 and via holes for interconnecting the wiring formed on the front surface side of the base material 3 and the internal wiring 4, between the internal wiring 4 and between the internal wiring and the wiring formed on the back surface side of the base material 3 ( (Not shown). On the back surface of the ceramic multilayer circuit board 2, a large number of input / output and power supply pins 5 as external terminals are arranged in a grid (ceramic) shape. The pin 5 is joined to the wiring formed on the back surface side of the base material 3 via a brazing material.

The semiconductor chip 6 is die-bonded to the surface of the ceramic multilayer circuit board 2. The wires 7 electrically connect a large number of pads of the semiconductor chip 6 and wirings on the surface of the ceramic multilayer circuit board 2. For example, the cap 8 made of an AlN sintered body is joined to the surface of the ceramic multilayer circuit board 2 around the semiconductor chip 6 by a solder layer 9 to hermetically seal the semiconductor chip 6. The radiation fin 10 is joined to the cap 8 via a brazing material layer.

In the pin grid array package 1 provided with such a ceramic multilayer circuit board 2 and pins 5, the pins 5 are soldered to the surface wiring (not shown) of a printed wiring board (motherboard) 11, for example. Connected by joining. The printed wiring board 11 includes the internal wiring 12, the surface wiring (not shown), and the internal wiring 1.
It has a through hole (not shown) for connecting the two to each other.

However, in the conventional pin grid array package 1 shown in FIG.
Since the heat generated in 1 is radiated through a large number of pins 5 attached to the back surface of the ceramic multilayer circuit board 2 other than the path passing through the heat radiation fins 10, the heat radiation performance is not always satisfactory. In particular, the power consumption of recent semiconductor chips has become higher and higher.
It is conceivable that a large amount of heat of W, about 100 W, is generated, and it is difficult to mount the semiconductor chip on the heat dissipation point in the ceramic package having the structure shown in FIG.

[0007]

The above-mentioned conventional ceramic package does not always have sufficient heat dissipation of the heat generated in the semiconductor chip, and in recent years it has been required to handle a semiconductor chip having higher power consumption. , A ceramic package with more excellent heat dissipation is desired.

The present invention has been made in order to solve such problems, and it is an object of the present invention to provide a ceramic package having extremely good heat dissipation without deteriorating the electrical characteristics and the high-density mounting property. is there.

[0009]

According to the present invention, there is provided a ceramic circuit board, a plurality of external terminals joined to a surface of the ceramic circuit board opposite to a surface on which a semiconductor chip is mounted, and a semiconductor chip mounting surface directly below the semiconductor chip mounting surface. A ceramic package, comprising: a heat dissipation inclusion provided on a surface of the ceramic circuit board located on a side where external terminals are joined.

The ceramic substrate of the ceramic circuit board is formed of, for example, a low dielectric constant material such as glass ceramic or mullite (dielectric constant: 4 to 7). When heat dissipation is important, the ceramic base material is formed of AlN, SiC or the like having high thermal conductivity. When the coefficient of thermal expansion is close to that of Si forming a semiconductor chip, for example, an LSI chip, and the reliability against thermal stress is emphasized, the ceramic base material is preferably made of AlN, mullite, or glass ceramic. In particular, AlN has an oxygen content of 0.005 to 10 atm% and a thermal conductivity of 130 to 280.
It is desirable to use W / m · K. In addition, since alumina is inexpensive and is a chemically stable substance, it can be widely used as the ceramic substrate.

On the surface of the ceramic circuit board, for example, a thin film wiring comprising a bonding layer of Ti, Cr or the like, an intermediate layer (barrier layer) of Ni, MMo, Pt or the like and a conductor layer of Cu, Al, Mo, Au or the like. Are formed. When the ceramic circuit board has a multi-layer structure, a refractory metal of W or Mo is generally used as the internal wiring. However, when a glass ceramic that is fired at a low temperature of about 1000 ° C. is used as the base material, a base metal such as Cu or Ag is used.
Is used.

As the external terminal, for example, Kovar (Fe-29% Ni-17% Co), Fe-Ni alloy,
A pin made of Cu alloy or the like is used. Such pins are
For example, 72 wt% is formed on the Ni layer formed on the back surface of the ceramic circuit board (the surface opposite to the mounting surface of the semiconductor chip).
It is joined by a brazing material such as% Ag-Cu, Au-Sn.

As the heat dissipation inclusion, for example, a ceramic having a high thermal conductivity such as an AlN sintered body or a SiC sintered body, or a conductive material having a high thermal conductivity such as Cu / W slag, Cu or Al is used. it can. To bond such a heat-dissipating inclusion to the ceramic circuit board, for example, a thin-film conductor layer having a three-layer structure in which a bonding layer, an intermediate layer (barrier layer) and a surface layer are sequentially laminated on the back surface of the ceramic circuit board. Are joined through. The joining layer is made of, for example, Ti, Cr, the intermediate layer is made of, for example, Ni, Pt, etc., and the surface layer is made of, for example, Au, Ag. Further, the heat dissipation inclusions are allowed to be bonded to the back surface of the ceramic circuit board by an active metal method using Ti or a method using a resin adhesive in addition to the thin film conductor layer. Further, when the heat radiation inclusion is made of the same AlN sintered body as the ceramic base material of the ceramic circuit board, it is possible to perform processing in the state of the green sheet before firing the ceramic to integrally form it. ..

The surface of the ceramic circuit board on which the semiconductor chip is mounted is provided with an A for hermetically sealing the semiconductor chip.
It is allowed to provide a ceramic or metal cap made of 1N sintered body or the like. Further, the cap may be fitted with a radiation fin in order to enhance heat radiation from the semiconductor chip. Examples of materials used for the heat radiation fins include ceramics such as AlN and AlN-BN, and metals such as Al.

An LSI chip or the like is used as the semiconductor chip mounted on the surface of the ceramic circuit board, and Au, for example, is formed on the surface of the ceramic circuit board.
Die bonded through the layers. Such a semiconductor chip is mounted by being connected to the thin film wiring of the ceramic circuit board by, for example, TAB, flip chip method, or wire bonding. As the bumps for the flip chip, for example, Au, Cu, or 95Pb-Sn solder can be used. For the wire bonding, for example, a wire made of Au, Al, Cu is used.

[0016]

According to the ceramic package of the present invention, the heat generated in the semiconductor chip can be eliminated by providing the heat dissipation inclusion on the surface of the ceramic circuit board located directly below the mounted semiconductor chip on the external terminal joint side. It can be satisfactorily discharged through the heat dissipation inclusions. Therefore, compared with the conventional pin grid array package in which only the pins are provided on the surface opposite to the mounting surface of the semiconductor chip, the heat generated in the semiconductor chip can be released more quickly, and the thermal resistance of the entire package is significantly reduced. You can

If the heat dissipation inclusion is formed of a conductive material and is joined so as to connect to the via hole of the ceramic circuit board, the heat dissipation inclusion serves as a ground wiring, a power supply wiring, or the like. It can be used, and resistance and inductance can be reduced.

[0018]

Embodiments of the present invention will be described in detail below with reference to FIG.

FIG. 1 is a sectional view showing a pin grid array package. However, FIG. 1 shows a state in which the pin grid array package is mounted on a printed wiring board (motherboard).

The pin grid array package 21 is provided with a ceramic multi-layer circuit board 22 of 40 mm square, for example. The ceramic multilayer circuit board 22 is made of, for example, Al.
Base material 23 made of N sintered body, wiring (not shown) made of, for example, Cu formed on the front and back surfaces of the base material 23, and internal wiring 2 made of, for example, W formed in the base material 23.
4, a via hole for interconnecting the wiring formed on the front surface side of the base material 23 and the internal wiring 4, between the internal wiring 4 and between the internal wiring and the wiring formed on the back surface side of the base material 23 ( (Not shown). An Au layer is formed by plating or the like on the die-bonding site on the surface of the ceramic multilayer circuit board 22. A Ni layer is formed by plating or the like on the external terminal joining portion of the wiring formed on the back surface side of the ceramic multilayer circuit board 22. A thin film conductor layer having a three-layer structure made of Ti / Ni / Au is formed as a power source wiring on a predetermined portion of the wiring formed on the back surface side of the ceramic multilayer circuit board 22. In addition, the ceramic multilayer circuit board 22
A frame-like cap-bonding thin-film conductor layer having a three-layer structure made of Ti / Ni / Au is formed on the peripheral portion of the surface of.

A large number of input / output and power supply pins 25, which are made of, for example, Kovar, are arranged in a lattice pattern (ceramic pattern) on the rear surface of the back surface of the ceramic multi-layer circuit board 22 and are 72 wt. % Ag-C
It is joined by a brazing filler metal.

The heat-dissipating inclusions 31 made of, for example, Cu / W slag are joined to a thin-film conductor layer as power supply wiring formed on the back surface of the ceramic multilayer circuit board 22 located immediately below the LSI chip mounting surface. .. The heat dissipation inclusion 31 has a size of 20 mm square.

In such a pin grid array package, for example, the LSI chip 26 is electrically connected to the die bonding portion on the surface of the ceramic multilayer circuit board 22 via a silver epoxy resin adhesive (trade name: H70E manufactured by Epotek Co., Ltd.), Mechanically joined. The LSI chip 26 has a size of 10 × 10 × 0.45 mm, and a plurality of Au pads are formed on the upper surface thereof. For example, C
The wires 27 made of u electrically connect the many pads of the LSI chip 26 and the wiring on the surface of the ceramic multilayer circuit board 22. For example, the cap 28 made of an AlN sintered body is bonded to the cap bonding thin-film conductor layer on the surface of the ceramic multilayer circuit board 22 by the Au—Sn brazing material layer 29 to hermetically seal the LSI chip 26.
For example, the radiation fin 30 made of Cu is used for the cap 2
No. 8 is joined via a brazing material layer.

The ceramic multilayer circuit board 2 described above
2, the pin grid array package 21 including the pins 25, the heat radiation inclusions 31 and the like, for example, joins the pins 25 and the heat radiation inclusions 31 to the surface wiring (not shown) of the printed wiring board (motherboard) 32. It is implemented by doing. The printed wiring board 32 has, for example, internal wirings 33 and surface wirings (not shown) and through holes (not shown) for connecting the internal wirings 33 to each other. The heat-dissipating inclusions 31 and the printed wiring board 32 are joined by using a thermal compound such as Pb-Sn solder or silicone grease. Further, when the heat dissipation inclusion 31 is made of ceramic, it is preferable to previously metallize the joint surface.

According to the pin grid array package of this embodiment having such a structure, the heat dissipation inclusions 31 are provided on the surface of the ceramic multi-layer circuit board 22 on the pin joint side, so that the ceramic multi-layer circuit board 22 is mounted on the ceramic multi-layer circuit board 22. The heat generated in the LSI chip 26 can be satisfactorily radiated to the printed wiring board 32 through the heat dissipation inclusion 31. Therefore, compared to the conventional pin grid array package in which only the input / output pins are provided on the surface of the ceramic multilayer circuit board opposite to the mounting surface of the LSI chip, the LSI
Since the heat generated in the chip can be quickly released, the thermal resistance of the entire package can be significantly reduced.

In fact, in a state in which the pin grid array package 21 of this embodiment shown in FIG. 1 is mounted on the printed wiring board 32 and in a state in which the conventional pin grid array package 1 shown in FIG. 2 is mounted on the printed wiring board 11. The thermal resistance was measured when air was sent in the direction of arrangement of the radiation fins 30 and 10 at 1 m / sec and 3 m / sec. As a result, as shown in Table 1 below, the pin grid array package 21 of this example provided with the heat dissipation inclusions 31 had extremely good heat dissipation. Table 1 Wind speed 1 m / sec 3 m / sec Example 3.5 ° C./W 2.1 ° C./W Conventional example 5.1 ° C./W 3.4 ° C./W

Further, the heat dissipation inclusion 31 is formed of Cu / W slag which is a conductive material, and the heat dissipation inclusion 31 is bonded to the thin film conductor layer connected to the via hole of the ceramic multilayer circuit board 22. The heat-dissipating inclusion 31 can be used as, for example, a power supply wiring, and the resistance and inductance of the power supply wiring can be reduced.

The ceramic package of the present invention is not limited to the pin grid array package described above. For example, it can be applied to a land grid array package using bumps as external terminals.

Further, the ceramic circuit board may not be formed with internal wiring, and may be composed only of wiring formed on the front and back surfaces of the ceramic base material and via holes for connecting the respective wirings.

Further, the shape of the heat radiating inclusion to be joined to the ceramic circuit board is not particularly limited, and for example, the heat radiating inclusion made of the same material as the pin as the external terminal and having a large diameter can be used for the external terminal. It is also possible to join at the same time as the pin.

[0031]

As described above in detail, the ceramic package according to the present invention has a very good heat dissipation property without impairing the electrical characteristics and the high-density mounting property, and can be mounted with a semiconductor chip with a large heat generation amount. As a result, it has a remarkable effect that it can be effectively used for a desktop computer or a laptop computer.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state in which a pin grid array package according to an embodiment of the present invention is mounted on a motherboard.

FIG. 2 is a sectional view showing a state in which a conventional pin grid array package is mounted on a motherboard.

[Explanation of symbols]

21 ... Ceramic package, 22 ... Ceramic multilayer circuit board, 25 ... Pin, 26 ... LSI chip, 28 ... Cap, 30 ... Radiating fin, 31 ... Radiating inclusion, 32 ...
Printed wiring board (motherboard).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kaoru Koiwa 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Research Institute Co., Ltd. No. 1 Incorporated company Toshiba Research Institute

Claims (1)

[Claims] 1. A ceramic circuit board, a plurality of external terminals joined to a surface of the ceramic circuit board opposite to a surface on which a semiconductor chip is mounted, and an external portion of the ceramic circuit board located immediately below the semiconductor chip mounting surface. A ceramic package, comprising: a heat-radiating inclusion provided on the surface on the terminal bonding side.