JPS62293745A - heat transfer element - Google Patents

Abstract

PURPOSE:To absorb the dispersion of the height and parallelism of an LSI chip by spirally winding a band made of a thin metal having a large number of slits vertically or obliquely in the longitudinal direction and forming a cylinder. CONSTITUTION:The upper end of a heat transfer element 2 acquired by spirally winding a metallic band 1 made of thin copper, to which slits are shaped vertically in the longitudinal direction, and forming a cylinder is fixed to a cooling plate 6 by solder while an LSI chip 3 is fastened to a base 5 by a solder ball 4. The lower end of the heat transfer element 2 is pushed lightly against and brought into contact with the LSI chip 3 directly or through a heat transfer compound, etc. Consequently, heat generated in the LSI chip 3 is transmitted over the cooling plate 6 through the heat transfer element 2, thus cooling the LSI chip 3. On the other band, a heat transfer element 2 is deformed easily to a barrel shape by the effect of the slits 11 without damaging heat transfer capacity to an LSI chip 3' having large height from the base 5, and the difference of the height of the LSI chip 3' is absorbed.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a heat transfer element, particularly a heat transfer element used for cooling an IC or an LSI chip.

[Prior Art] With the increase in speed and capacity of electronic meters, the heat generation density of IC and LSI packages is also increasing, and cooling technology for IC and LSI chips is becoming increasingly important. The cooling methods include a forced air cooling method in which a small heat sink is attached to each depth and cooled with air, a liquid cooling method in which the chip is directly immersed in an electrically insulating liquid such as Freon (f1), and cooled.
Alternatively, there is a heat conduction method in which the chip is cooled via a heat transfer element between the chip and the cooling plate. Each of these cooling methods has its advantages and disadvantages, and the target electronic KI C', t
Currently, J: is used depending on Furukawa's policy and each manufacturer's policy.

As an example of the above-mentioned heat conduction method, the piston method shown in FIG. 6, which is employed in the model No. 3081 of Company L;t113M, has been well known. In this method, L
The heat generated in the SI chip 3 is transferred to the spherical parts of the screws 1 to 9 (inserted into the cold IJ plate 6 via the spring 10) that are in contact with the chip 3, and the heat is transferred several μm from the side of the piston 9. It is transmitted to the water-cooled cooling plate 6 through the gap. Naj
3. The gap is filled with helium gas to improve heat conduction.

The biggest problem with this heat conduction method (, 1 package 3Aγ)
The second problem is how to absorb variations in the height and parallelism of the large number of LSI chips arranged, as well as thermal expansion. The above-mentioned piston method solves this problem by providing a small gap as shown in the figure, using a spring, and making the piston tip spherical, and is currently one of the best methods. has been done.

[Problems to be Solved by the Invention] However, this method has the following drawbacks. In other words, since the contact between the IsI depth 3 and the piston 9 is through a flat and spherical surface, the contact area between the two is small, and because helium gas is interposed between the piston 9 and the cooling plate 6, , it is not possible to significantly reduce thermal resistance from the current level. Therefore, when the degree of integration of L S, I increases by -m and the amount of heat generated increases, this method cannot sufficiently cool the part.

The present invention has been made in view of the above circumstances, and its purpose is to solve the drawbacks of the prior art described above and provide a novel heat transfer element that can significantly reduce thermal resistance. It's about doing.

[Means for solving the problem] The gist of the present invention is that a cylinder is formed by spirally winding a thin metal band having a large number of slits perpendicularly or diagonally to the length direction. The heat transfer element is Here, it is preferable to insert a spacer into the non-slit part between the metal bands, and also to integrate a metal plate with good heat conduction on the end face of the metal band. It may be installed as shown. Note that the spiral metal band forming the cylinder does not need to be one continuous piece, and may be made of a plurality of pieces to form a plurality of rows of vortices.

[How it works: The slits in the thin metal strip give the cylindrical heat transfer element elasticity, so it bends and deforms into a barrel shape under even the slightest load, thereby reducing variations in the height and parallelism of the LSI chip. can be absorbed.

[Example〕 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a thin copper metal strip 1 with slits formed perpendicular to its length is spirally wound to form a cylinder to form a heat transfer element 2. be.

Although not shown, the outer end of the spiral is fixed with solder or the like to prevent it from unraveling. FIG. 2 shows the state in which the heat transfer element 2 is used, and the upper end of the heat transfer element 2 is fixed to the cooling plate 6 with solder. On the other hand, the LSI chip 3 is fixed to a substrate 5 (made of ceramic or the like) with solder balls 4. The lower end of the heat transfer element 2 is lightly pressed into contact with the LSI chip 3 either directly or via a heat transfer compound or the like. Thus 1. The heat generated in the SI chip 3 is transferred to the cooling plate 6 via the heat transfer element 2, thereby cooling the LSI deep 3 (
(See Figure 2(a)). On the other hand, for an LSI chip 3' having a large height from the substrate 5, the heat transfer element 2 is easily deformed into a barrel shape due to the effect of the slit 11 without impairing the heat transfer ability, and the height of the LSI chip 3' is increased. The difference in height can be absorbed (see FIG. 2(b)).

Next, FIGS. 3 and 4 show another embodiment of the present invention, in which spacers are wound around the upper and lower ends of each layer of the spiral metal strip 1. As a result, when the heat transfer element 2 is deformed into a barrel shape, there is less interference between the layers of the metal band 1, and the deformation becomes even easier. Note that as the material for the spacer 7, it is desirable to use a metal such as copper or aluminum in order to improve heat conduction in the radial direction.

FIG. 5 shows yet another embodiment of the present invention, in which circular metal heat transfer devices 8 are attached to both ends of a cylindrical heat transfer element 2 by soldering or the like.

Thereby, when the area of the upper surface of the LSI deep 3 is smaller than the area of the end surface of the heat transfer element 2, heat can be dispersed in the radial direction, and the entire heat transfer element 2 can be effectively utilized.

[Effects of the Invention] As described above, the heat transfer element according to the present invention bends and deforms into a barrel shape with a slight load due to the slits provided in the thin metal strip, thereby reducing variations in the height and parallelism of LSI chips. Can be absorbed.

In addition, the contact area between the heat transfer element and the LSI bump is large,
Moreover, since the heat conduction is between metals with good heat conductivity, the thermal resistance can be extremely small.

In this way, the heat transfer element according to the present invention has a high level of both springiness under small loads and low thermal resistance, and is suitable for ICs.
It is extremely excellent for cooling spears and SI chips.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention, Fig. 2 is an explanatory diagram showing its usage state, Fig. 3 is a plan view showing another embodiment of the invention, and Fig. 4 is a longitudinal section thereof. 5 are front views showing still another embodiment of the present invention, and FIG. 6 is an explanatory view showing a conventional example. 1: Metallic band, 2: Heat transfer element, 3.3': LSI chip, 4: Solder ball, 5: Base, 6: Cooling plate, 7: Spacer, 8: Heat transfer plate, 9: Piss ton, 10 springs, 11: slit.

Claims (3)

[Claims] (1) A heat transfer element characterized by forming a cylinder by spirally winding a thin metal band having a large number of slits perpendicularly or diagonally to the length direction. (2) The heat transfer element according to claim 1, wherein a spacer is inserted into a non-slit portion between the spirally wound metal bands. (3) The heat transfer element according to claim 1 or 2, characterized in that a metal plate with good thermal conductivity is attached to the end surface of the metal band so as to be integrated with the end surface of the metal band. .