JPH11251495A - Electronic circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow all semiconductor elements or chip carriers to appropriately adhere to a single cooling member, even if the height of the semiconductor elements or the chip carries scatters and components undulate initially and to allow a component member to be appropriately adhered, even if it is deformed due to the heat generated at operation. SOLUTION: A heat transfer member 7 where a plurality of metal small- gauge wires are formed and grease containing silver fine particles between a semiconductor element or a chip carrier 2 and a cooling member, and the semiconductor element or the chip carrier 2 and the cooling member 3 are allowed to adhere by filling a grease containing silver fine particles into the heat transfer member 7, thus achieving a satisfactory heat-transfer structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit device on which semiconductor elements are mounted at a high density.

[0002]

2. Description of the Related Art In recent years, high-speed operation and high-density semiconductor devices used in electronic circuit devices have been rapidly advanced. As a result, the number of external connection terminals increases as the number of semiconductor elements increases, and high-density mounting on a semiconductor mounting substrate is required.

In order to meet this demand, a method of mechanically and electrically bonding a module constituting an electronic circuit device to a semiconductor mounting substrate via an electrode provided on an electrode terminal of a semiconductor element or a chip carrier is adopted. Have been.
However, in this method, since the contact area between the semiconductor element and the mounting board is reduced, the thermal resistance between the semiconductor element and the mounting board is increased. Had to be specially provided.

Therefore, a method has been devised in which a heat radiating member is brought into close contact with the back surface of the semiconductor element to create a new heat radiating path.
However, in a method in which a single heat radiation member is closely attached,
The following issues were found.

First, there is a variation in height of a semiconductor element or a chip carrier. Since a large number of semiconductor elements or chip carriers are mounted in an electronic circuit device, variations in the height of electrodes (hereinafter referred to as “protruding electrodes”) attached to the electrode terminals of the semiconductor elements and variations in the thickness of the semiconductor elements may occur. In addition, the height and inclination of the surface of the semiconductor element bonded on the wiring substrate vary, and a single plane is not formed.

As a result, when individual semiconductor elements are to be cooled by a single heat radiating member, all the semiconductor elements do not adhere to the heat radiating member. If the height of the semiconductor element is low, a gap is generated and the heat conductivity is deteriorated, and the semiconductor element is not sufficiently cooled. Conversely, if the height of the semiconductor element is too high, an excessive force is applied due to the pressing of the heat radiating member, and there is a possibility that the protruding electrode is deformed or broken.

As another problem, thermal deformation of the semiconductor device during operation may be considered. The semiconductor element generates heat when the power is turned on. Due to the temperature change due to the repeated on / off of the semiconductor element, the components of the semiconductor device undergo thermal deformation. At this time, if the rigidity of the individual semiconductor element or the heat transfer member attached to the chip carrier that is in close contact with the single heat radiation member is high, compressive / tensile stress is generated in the semiconductor element or the protruding electrode, resulting in long-term operation. The semiconductor element or the protruding electrode may be broken.

The following cooling structure has been devised to solve these problems. Japanese Patent Application Laid-Open No. 7-297327 discloses a method in which a contact surface of a semiconductor element having a variable height is brought into contact with a heat radiating member through a plurality of thin metal wires. This is because the bending of the plurality of fine metal wires acts as a cushion, and cancels the height variation of the semiconductor element.

[0009]

The structure described in Japanese Patent Application Laid-Open No. 7-297327 is such that the ends of a plurality of fine metal wires are brought into contact with a heat dissipating member and the heat of the semiconductor element is transmitted to the heat dissipating member. Since the area of the contact portion of the thin metal wire is small, heat cannot be sufficiently transmitted in the case of a semiconductor element having higher heat generation.

An object of the present invention is to dispose a heat transfer member having thermal conductivity and absorbing deformation between a cooling surface or a heat transfer surface of a semiconductor element and a heat radiating member, thereby improving the height of the semiconductor element. It corresponds to the variation of the height and the thermal deformation during operation,
It is an object of the present invention to provide an electronic circuit device capable of sufficiently transmitting heat of a semiconductor element to a heat radiating member and absorbing thermal deformation during operation even when the amount of heat generated by the semiconductor element increases.

[0011]

In order to achieve the above object, the present invention employs any one of the following structures.

[0012] A heat transfer member filled with grease or oil containing silver fine particles is provided between a plurality of semiconductor elements or chip carriers having different heights and a single heat radiation member common thereto. The semiconductor element or the chip carrier and the heat transfer member were brought into close contact with each other via the heat transfer member.

The above-described heat transfer member has a structure in which one end of a plurality of thin metal wires is bundled and fixed, and two sets of the thin metal wires are used to face the free ends of the thin metal wires.

The low-melting-point metal layer formed by coating the heat-dissipating surface of the semiconductor element or the chip carrier with the low-melting-point metal has a thickness corresponding to the height variation of the semiconductor element or the chip carrier and the initial undulation of the components. It has a shape and serves to attach the heat transfer member to a predetermined position.

The heat transfer member filled with grease or oil absorbs thermal deformation generated during operation. The grease or oil to be filled is in close contact with the formed fine metal wire to reduce the contact thermal resistance and to make a good heat transfer state.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic perspective view of the present invention, in which some components are cut away to explain the internal structure.
Reference numeral 1 denotes a module that constitutes the electronic circuit device of the present invention, and includes a chip carrier 2, a heat radiation member 3, a wiring board 4, and the like. A plurality of chip carriers 2 are arranged on the wiring substrate 4 in a grid pattern. Reference numeral 5 denotes a frame joined to four sides of the wiring board 4. In this embodiment, the chip carrier 2 is made of aluminum nitride having excellent thermal conductivity, and the frame 5 is made of an iron-nickel alloy.

Reference numeral 6 denotes a connecting pin provided on the rear surface of the chip carrier 2 mounting surface of the wiring board 4, and is connected to the chip carrier 2 through the inside of the wiring board. The module 1 is electrically and mechanically connected by inserting the connecting pins 6 into a large substrate (not shown). The heat dissipating member 3 is made of nickel-plated copper for corrosion prevention, has a coolant passage 3a inside, and a coolant inflow / outlet 3b on the upper surface.
Is provided.

Reference numeral 7 denotes a heat transfer member, which is provided between the chip carrier 2 and the heat radiation member 3. The heat dissipating member 3 and the frame 5 are bolted (not shown) to form the module 1. Here, liquid cooling is taken as an example, but in the case of air cooling, the heat radiating member 3 may be a heat radiating fin made of aluminum or the like, and the present invention is not limited to a cooling method.

FIG. 2 is an enlarged vertical sectional view including a chip carrier 2 showing a detailed structure. However, a cross section of the chip carrier 2 is not shown to avoid complexity. In the drawing, reference numeral 8 denotes protruding electrodes for connecting the chip carrier 2 and the wiring board 4, and many are arranged on the joint surface between the chip carrier 2 and the wiring board 4. Usually, the protruding electrode 8 is made of solder, and electrically connects a semiconductor element (not shown) in the chip carrier 2 to the wiring board 4.
It plays a role of mechanically fixing the chip carrier 2 thereon.

The heat transfer member 7 is formed with a plurality of fine metal wires 7a. The heat transfer member 7 is made of aluminum nitride having a good thermal conductivity, and one of the chip carriers 2 is formed by the low-melting-point metal 9 in an arrangement relationship in which the forming surfaces of the metal wires 7a face each other.
One is fixed to the heat radiation member 3. Grease (not shown) having excellent thermal conductivity is filled between the thin metal wires 7 a formed on the heat transfer member 7.

Since grease is inferior in heat conductivity to metal, in order to enhance the heat conductivity, fine particles of metal such as silver, copper and aluminum, or fine particles of non-metal such as carbon, aluminum nitride, zinc oxide and silicon dioxide are used. Must be dispersed.

However, if the fine particles are excessively dispersed, they become rigid and lose elasticity. In the present embodiment, fine flake-like silver fine particles having excellent thermal conductivity are dispersed and contained in grease. For this reason, while maintaining good elastic properties,
Has excellent thermal conductivity. The filled grease enhances the thermal adhesion between the opposed heat transfer members 7 and reduces the contact thermal resistance.

One embodiment of the present invention for the variation in the height of the chip carrier and the initial undulation of the components will be described with reference to FIGS. 3 and 4. FIG. Due to undulations on the wiring board 4 on which the chip carrier is mounted, variations in the dimensions of the chip carrier alone, and assembly errors, variations in the height of the chip carrier when assembled are caused. In this embodiment, the distance between the chip carrier and the heat transfer member 7 varies from 2.05 mm to 2.21 mm with respect to the target of 2.12 mm. Therefore, the heat of the chip carrier is transferred to the heat transfer member 7.
Therefore, it is necessary to reduce the thermal resistance between the chip carrier and the heat radiating member 3 as much as possible.

FIG. 3 shows a chip carrier 2 showing a detailed structure.
It is a longitudinal section containing a, 2b and 2c. However, the cross sections of the chip carriers 2a, 2b, 2c are not shown.

The grease (not shown) filled between the opposed heat transfer members 7 is inferior in thermal conductivity as compared with the low melting point metal 9, so that the relative distance at which the contact heat resistance becomes a certain value or less. The heat transfer member 7 is installed. The difference in the distance between the chip carrier and the heat radiating member 3 which occurs at this time is adjusted by changing the thickness of the low melting point metal 9 used for fixing the heat transfer member 7. Thus, even if the height of the chip carriers 2a, 2b, 2c varies, the heat of each chip carrier can be efficiently transmitted to the heat radiation member 3. In the example of the present invention, nitrogen gas is sealed to prevent oxidation of the components in the package, and the O-ring 10 installed in the groove of the frame 5 maintains the hermeticity to enhance long-term reliability.

FIG. 4 is a sectional view of a contact portion showing a fixed state between the heat transfer member 7 and the chip carrier 2 with the low melting point metal 9 and a fixed state between the heat transfer member 7 and the heat radiating member 3 with the low melting point metal 9. It is a conceptual diagram, and swelling of a surface is emphasized for explanation. The heat transfer member 7 has a structure in which a plurality of thin metal wires having one free end are fixed, and the heat transfer members 7 are arranged facing each other with the forming surfaces of the thin metal wires 7a facing each other to form a set of heat transfer members. Although the surfaces of the chip carrier 2, the heat dissipating member 3, and the heat transfer member 7 to which the low melting point metal 9 is fixed are smooth, they are not microscopically flat but slightly undulated. These undulations can be compensated for by the low melting point metal 9, and the heat of each chip carrier can be efficiently radiated through the heat transfer member 7.
Can be communicated to

An embodiment of the present invention for thermal deformation during operation will be described with reference to FIGS. FIGS. 5 and 6 are conceptual views of the longitudinal section of the contact portion showing the structure of the heat transfer member 7 and the grease 11, wherein FIG. 5 is before operation and FIG. 6 is in operation. FIG.
Grease 11 is filled in the gap between the heat transfer members 7 facing the formation surface of the thin metal wire 7a as described above, and the grease 11 has flake-like silver fine particles 11a dispersed almost uniformly.
The heat from the chip carrier (not shown) is
The heat can be transmitted to the heat radiating member 3 (not shown) via the thin metal wire 7a and the filled grease 11. When the power is supplied to the chip carrier in this state, the semiconductor element generates heat, and each component constituting the module is deformed by the heat. As shown in FIG. Will not be maintained.

In this embodiment, even when the components are deformed, the heat from the chip carrier (not shown) is transferred to the fine metal wires 7 a formed on the heat transfer member 7 and the filled silver fine particles 11.
Heat dissipation member (not shown) via grease 11 containing a
Can be communicated to The grease 11 has good viscous properties and has an appropriate bonding force, so that the grease does not flow out, and the required amount of the grease 11 can be held for a long time. As a result, high reliability can be obtained even in the long term.

[0029]

According to the present invention, a semiconductor element having a height variation can be thermally connected to a single heat dissipating member for cooling. Further, even during operation, the semiconductor chip and the heat dissipating member can be cooled. Because of the thermal connection, a highly reliable electronic circuit device can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view including a partially cut surface of an electronic circuit device module according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view including a chip carrier according to one embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of an entire module including a chip carrier according to one embodiment of the present invention.

FIG. 4 is a conceptual diagram of a longitudinal section showing a contact state of the heat transfer member shown in FIG.

FIG. 5 is a conceptual diagram of a vertical section of a contact portion before thermal deformation showing a state of grease filled between heat transfer members.

FIG. 6 is a conceptual diagram of a vertical section of a contact portion showing a state of thermal deformation of the components shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Module, 2 ... Chip carrier, 3 ... Heat dissipation member,
3a: flow path, 3b: inflow / outlet, 4: wiring board, 5: frame, 6: connecting pin, 7: heat transfer member, 7a: thin metal wire,
8 ... projecting electrode, 9 ... low melting point metal, 10 ... O-ring, 11
... Grease, 11a ... Silver fine particles.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Keiji Taguchi 502 Kandachicho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratories, Hitachi Ltd. Inside the mechanical laboratory

Claims (1)

[Claims] An electronic circuit device having a heat dissipation member and a wiring board on which a plurality of semiconductor elements or chip carriers thereof are mounted, and a heat transfer member having a plurality of fine metal wires are provided to face each other. An electronic circuit device, wherein a grease or an oil containing Ni is filled between the heat transfer members, and the semiconductor element or a chip carrier thereof is in contact with the heat dissipation member.