KR100632307B1 - Integrated Circuit chip mounting module with metallic heat sink - Google Patents

Abstract

The heat dissipation characteristics are improved by attaching a metal heat dissipation plate having an air vent formed on a surface in contact with a circuit board having an integrated circuit (IC) chip.

The heat sink of the present invention has a thermally conductive member for attaching an integrated circuit (IC) chip by providing one or more holes through which air can escape through the integrated circuit (IC) chip or forming a thin groove. There is no air remaining while bonding to prevent the formation of an air pocket (air pocket).

In addition, by cladding the aluminum alloy plate material for the heat sink with a metal plate having excellent thermal conductivity such as copper or silver, there is an effect of improving heat dissipation when using only aluminum.

Metal heat sink, air exhaust, cladding, integrated circuit (IC) chip, anodization, aluminum

Description

Integrated Circuit chip mounting module with metallic heat sink             

1 is an integrated circuit chip mounting module having a conventional heat sink.

Figure 2 is an integrated circuit chip mounting module having a heat sink with conventional unevenness.

3 is a cross-sectional schematic diagram of the aluminum anodization layer.

4 is a front view showing an example of a heat sink according to the present invention.

5 is a front view showing a thermally conductive resin sheet according to the present invention.

6 is a schematic view of an integrated circuit chip mounting module having a heat sink according to the present invention.

* Description of the symbols for the main parts of the drawings *

1: heat sink 2: air outlet

3: air exhaust groove 4: heat conductive resin sheet

The present invention relates to an integrated circuit (IC) chip mounting module for preventing damage to the integrated circuit (IC) chip due to overheating by installing a metal heat sink in the integrated circuit (IC) chip, and more specifically, an integrated circuit (IC) To improve the heat dissipation efficiency by forming a structure capable of discharging air to the portion where the chip and the metal heat dissipation plate is bonded, or by forming a metal layer having high corrosion resistance on the metal layer having high thermal conductivity.

Conventionally, the heat generation amount of integrated circuit (IC) chip has been solved by natural convection and heat conduction. However, as the integration degree of integrated circuit (IC) is increased and the width of circuit wiring is narrowed, heat generation due to increase of electric resistance is integrated circuit (IC). The chip is damaged. In particular, computers, flat panel displays PD, LCD, EL, etc. attach a separate heat sink to protect the integrated circuit (IC) that generates a large amount of heat.

There are many materials that can be used as the heat sink, but the metal has the advantage of excellent thermal conductivity and low manufacturing cost. Among them, silver is the most excellent, followed by 4.173 W / cm-K, copper 3.937 W / cm-K, gold 2.913 W / cm-K, and aluminum 2.165 W / cm-K. However, since it is difficult to attach the heat sink directly to the chip, adhesive heat conductive resin is used as the adhesive member.

The thermally conductive resin to which metal fine powder, metal oxide, silicon, etc. are added is made into an adhesive sheet or paste and used as an adhesive member. U.S. Pat.Nos. 6,451,155, 6,228,965, 6,162,319, 6,123,799, 6,086,994, 5,931,222, 5,831,828, 5,741,579 introduce sheet heat sinks. In addition, U.S. Patent No. 5,783,862 introduces a method of weaving a thermally conductive wire into a mesh structure and using it as a thermal conductor in combination with silicon grease or paraffin. Thermally conductive sheets are relatively conductive, with Cos-therm products ranging from 0.018 to 0.0433 W / cm-K, the remainder being 0.004 to 0.02 W / cm-K, less than one tenth of metal.

For example, FIG. 1 illustrates the bottom surface of the integrated circuit chip 58 and the printed circuit board 40 mounted on the flexible printed circuit board 40 as a heat dissipation method introduced in US Pat. No. 6,703,702. The heat dissipation effect is obtained by attaching the flat aluminum heat sinks 70 and 76 to the heat conductive resin sheet 68. However, in such a method, air pockets are often formed due to air remaining between the chip 58 or the printed circuit board 40 and the resin sheet 68.

In addition, as shown in FIG. 2, the heat dissipation plate 22, the silicon adhesive tape 21, and the adhesive metal thin plate 20 having irregularities formed on the cap 18 of the chip 12 are laminated to obtain a heat dissipation effect. This is described in US Pat. No. 5,931,222. In this case, as in the prior art, if the integrated circuit (IC) is not in close contact with the heat sink, the air layer having a very low thermal conductivity of 0.0003 W / cm-K has a heat insulation effect, rather adversely affects heat radiation There is.

As a solution to this problem, there is a method of minimizing the air layer remaining by contacting with a paste compound mixed with a metal oxide. However, this method improves adhesion, but the compound has a level of 0.004W / cm-K, which is one hundredth of that of metal and 1/5 to 1/10 level of thermal conductivity compared to the thermally conductive sheet. There are disadvantages.

Therefore, the present invention was created to solve the above problems, and improves the adhesiveness by forming an air discharge structure to prevent the insulating air layer formed due to the poor adhesion between the heat sink and the thermal conductive member in contact with the circuit board An object of the present invention is to provide an integrated circuit (IC) chip mounting module having a metal heat sink.

It is another object of the present invention to provide an integrated circuit (IC) chip mounting module having a metal heat sink that can improve thermal conductivity by using a heat sink having a clad structure bonded to a metal having excellent thermal conductivity and a metal having excellent corrosion resistance. .

It is still another object of the present invention to provide an integrated circuit (IC) chip mounting module having a metal heat dissipation plate which effectively improves the problem of thermal conductivity deterioration during surface treatment of a heat sink material in the prior art by changing the surface treatment method. have.

In order to achieve the above object, the present invention forms a through hole for drilling or venting through the air vent at a position coinciding with the position to which the integrated circuit is attached, and the hole or cut at the same position in the sheet-type thermal conductive resin. An integrated circuit (IC) chip mounting module which prevents formation of an air pocket that may occur when attaching a heat sink by forming a line, is described in detail with reference to the accompanying drawings. Is as follows.

Heat sink (1) used in the present invention is formed on the one surface for the heat dissipation (Fin) and the opposite surface is a flat surface, both sides of the planar shape that can be both in contact with the integrated circuit chip (6) It is possible. As shown in FIG. 4A, the heat dissipation plate 1 drills an air outlet 2 having a small diameter at a position contacting the integrated circuit chip 6 to allow air discharge. The more air outlets (2) or the larger the diameter, the better the air is released and the greater the prevention effect of the insulating air layer, but too many air outlets (2) are expensive to manufacture parts, and the contact area is small, reducing the heat conduction effect. There is.

In addition, forming the air discharge groove 3 in the heat sink 1, as shown in Figure 4b has the same effect. The air discharge groove 3 shows horizontal parallel grooves in the drawing, but the groove 3 is vertically or diagonally formed or intersects with each other to form a groove that intersects each other. Can be prevented from forming the insulation air layer. It is also possible to simultaneously form the air outlet 2 and the groove 3. In the present invention, the area occupied by the air discharge is 30% or less, preferably 10% or less in the area in contact with the integrated circuit chip. If the area of the air exhaust portion is more than 30%, the performance is greatly reduced as a heat sink, so it is limited.

If the means for adhering the heat sink 1 to the integrated circuit chip 6 is a heat conductive resin sheet 4, instead of the air outlet 2 formed in the heat sink 1 or the groove 3 for air discharge, The sheet adhesive sheet is left at the position where the integrated circuit chip 6 is attached, and only one row of the sheet portions are cut to form an air discharge groove, or as shown in FIG. 5, the air discharge groove 5 is formed by a dotted line. When attaching (4) to the circuit board or the integrated circuit chip 6, formation of an air pocket can be completely prevented.

The heat sink used in the present invention is often made of aluminum, mainly aluminum, alloys thereof, magnesium or alloys thereof. Of course, in the heat sink made of copper alloy or the heat sink in the case of wet or dry plating, the above air outlet or groove is formed. However, aluminum or magnesium often forms anodizing or chemical conversion coatings for corrosion resistance. Originally, aluminum combines with oxygen in the air to form a dense and thin film. An oxide film of about 1 to 3 nm is naturally produced to prevent oxidation. However, there is a problem that the natural oxide film is thin and unevenly generated, and thus, in the related art, an anticorrosive coating of about 5 to 30 μm is formed through anodization.

However, in the present invention, since these films have thermal conductivity of 1/5 to 1/10 of the original metal, in order to prevent thermal conductivity deterioration due to these coatings, the thickness is 5 탆 or less, and preferably 3 탆 or less. It is characterized by forming thin. As shown in FIG. 3, in the initial stage of anodization, a dense barrier layer is formed, and as time passes, a porous layer having air holes perpendicular to the center is formed. In the present invention, the porous layer is suppressed to prevent the thermal insulation effect.

In the present invention, a thin and dense barrier layer is formed to obtain a coating having excellent corrosion resistance and thermal conductivity. A short time treatment in a sulfuric acid bath or a boric acid or boric acid-sulfuric acid bath (BSAA method, detailed in the Aircraft Maintenance Pollution Prevention Implementation Handbook, ed. 1, 1996) is advantageous for this. Chromic acid baths are advantageous for thin anodization but have limited application due to the environmental impact of chromium. In addition, anodization by a fish bath, a mixed acid bath in which organic acids and sulfuric acid are mixed, or the power supply waveform may be modified to control the anodic oxide film. Commonly, the direct current method is used, but there are other methods such as an alternating current method, incomplete rectification, or anodizing method using a direct current pulse wave.

In addition to the anodization methods listed above, methods such as the chemical conversion coating method can also be used in the present invention.

Unlike the anodized film by the electrical method, the chemical film has the advantage that the formation of the corrosion resistant film is quick and the treatment cost is low because the treatment facility is simple. On the other hand, the film cannot be formed thick, and the film is inferior in abrasion resistance, but has a suitable function as a heat sink. However, the general chemical film contains hexavalent chromium ions for corrosion resistance, so there is a problem in that it should be limitedly used. Alkali chromate-based compounds containing trivalent chromium ions that are less toxic than hexavalent are available, but the coating becomes porous and chromium-free zinc phosphate-based baths have limited disadvantages in that the membranes are destroyed at high temperatures above 60 ° C. .

Hereinafter, a heat sink having a clad structure in which a metal layer having high corrosion resistance is formed on one side or on both outer sides of a member made of a metal layer having high thermal conductivity, which is the second invention of the present invention.

Most heat sinks are used by forming anodized films on aluminum materials or coloring dyes on anodized films. Therefore, the thermal conductivity effect depends on the thermal conductivity of aluminum, which is only about 55% of copper as mentioned above. However, copper has a disadvantage of having a low corrosion resistance, cyan generated by carbon dioxide, moisture, etc. in the atmosphere. To replace this, it is possible to consider brass, aluminum bronze, copper, etc., which have excellent corrosion resistance, but since their thermal conductivity is about 1/4 to 1/8 of pure copper, they have a lower thermal conductivity than aluminum. Rather, they can be applied to surfaces that require corrosion resistance. Accordingly, the present invention provides a heat radiation material having a clad structure in which a heat conductive layer is formed of a material having excellent thermal conductivity and a material having excellent corrosion resistance is bonded to a portion exposed to the outside. If the heat sink is mostly covered with a thermally conductive resin, only one surface of the heat sink may be clad with a material having excellent corrosion resistance except for the surface in contact with the resin.

The production of the heat radiation material of the clad structure will be described below.

First, an aluminum plate is formed on the outer surface for corrosion resistance, and a clad structural material using copper plate as an example of a heat conductive layer will be described. The aluminum coil mounted on the uncoiler is heated to a temperature range of 300 ~ 500 ℃ through a heating device, and in the copper coil mounted on the other uncoiler, a cold copper plate comes out and laminated with an aluminum plate to reduce the reduction ratio of 25 ~. Rolling to 40% strongly bonds the two materials together. If the structure of joining aluminum on both sides of the upper and lower, you can work by installing an additional aluminum uncoiler. If the unevenness is to be formed on one surface, the aluminum plate heated during rolling may form the unevenness by supplying a thick aluminum material to the bottom and contacting the unevenly formed roller. As the heat conductive layer material, a material excellent in heat transfer such as silver and gold can be used in addition to copper.

In addition to the aluminum-copper clad materials described above, the clad structural material is applied with aluminum, copper alloy, nickel, nickel plating, chromium plating, rhodium plating, tin plating, etc. on the outer surface of corrosion resistance, and has excellent thermal conductivity. Includes all materials applied.

Hereinafter, the heat sink manufacturing according to the present invention will be described in detail through examples. However, the present invention is not limited to the following examples.

The aluminum 1100 material was processed into the shape shown in FIG. The air exhaust grooves 3 were formed in parallel in two rows with a width of 0.5 mm, and the air exhaust holes were processed with a drill of 0.8 mm diameter. After that, finish the edges and finish degreasing in acetone for 5 minutes. The degreased product is pickled in a 20% sulfuric acid solution and then passed through the anode in a 20% sulfuric acid bath. It is common to provide an aluminum plate to the cathode and supply a voltage of 12 to 24V DC. In this embodiment, the voltage is set to 15V. The current density is about 8 ~ 10 A / dm ² . After anodizing, the solution is neutralized by soaking in 10% aqueous sodium hydroxide solution and then colored if necessary. In this embodiment, a separate coloring process is omitted. Finally, it was immersed in boiling water for 5 minutes and then dried.

In the product thus obtained, anodized film was formed at a thickness of 5 µm for 15 minutes according to the energization time, 2.5 µm for 8 minutes, and 1 µm for 4 minutes. However, in the clad structure heat sink, there is a risk of corrosion when the heat conductive layer material is copper or silver, and only the heat sink in which aluminum is clad on both surfaces is subjected to anodization.

With this product, a thermal conductive resin sheet was attached to the naked eye to check whether a residual air layer was formed. As a result, both cases having through-holes and air vent grooves were found to have good results.

As described above, the present invention prevents the thermal insulation effect caused by the residual air layer during the attachment of the thermal conductive resin, which has been used in the conventional IC chip mounting module, and heats the heat sink by cladding a material having excellent thermal conductivity and a material having excellent corrosion resistance. By constructing there is an effect that can improve the heat transfer performance.

Claims (8)

A second surface opposite the first surface having at least one integrated circuit chip; In the integrated circuit chip mounting module having a heat sink attached to the second surface of the circuit board consisting of or attached to the second surface and the integrated circuit chip,  The heat sink is attached by a heat conductive resin sheet or a paste-like heat conductive resin; The heat sink is characterized in that it comprises any one or all of the air discharge hole perforated in the thickness direction of the heat sink, the air discharge groove formed longer than the attachment surface to which the heat conductive resin sheet or paste-like heat conductive resin is attached. Integrated circuit chip mounting module. The integrated circuit chip mounting module of claim 1, wherein the heat sink is made of aluminum, magnesium, or an alloy thereof, and an oxide film or a chemical film is formed on the surface of the heat sink to have a thickness of 5 μm or less. The integrated circuit chip mounting module of claim 1, wherein when the heat sink is attached to the heat conductive resin sheet, the heat conductive resin sheet has at least one air discharge groove formed in a straight line or a dotted line. The method of claim 1, And the heat sink is a clad structure in which a metal layer having a high thermal conductivity is formed on one side or an outer both side of a member made of a metal layer having high thermal conductivity. The integrated circuit chip mounting module of claim 4, wherein the high thermal conductivity metal layer is formed of one of copper, silver, and gold or a composite thereof. The integrated circuit chip mounting module of claim 4, wherein the metal layer having high corrosion resistance is made of aluminum, gold, an alloy thereof, or a copper alloy, or a composite thereof. The metal layer of claim 4, wherein the metal layer having high corrosion resistance is made of one or an alloy of nickel plated, chromium plated, gold plated, rhodium plated, and tin plated to be wet or dry plated, and has a thickness of 3 μm or less. Integrated circuit chip mounting module. The area occupied by one or both of the air exhaust holes or the air exhaust grooves in the heat sink is less than 30% of the integrated circuit chip area in contact with the integrated circuit chip. Integrated circuit chip mounting module, characterized in that to be.

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