JPH08125363A - Structure for shielding integrated circuit - Google Patents

Abstract

PURPOSE: To provide the title shielding structure for electromagnetically shielding an integrated circuit without disturbing the cooling operation by a method wherein the suction port of cooling air to a motor driven fan and an exhaust port from a cooling unit are provided on a shielding body covering an integrated circuit and the cooling unit mounted thereon end pressing them down. CONSTITUTION: A cooling unit 8 is mounted on a package of an integrated circuit 5. A shielding body 25 is formed on a main surface 26 while a suction port 27 is formed on the position aligned with the suction port 13 of the cooling unit 8. The position of this cooling unit 8 is specified by the four side bent parts 28, 29 of the shielding body 25. The space between these bent parts 28, 29 and a circuit substrate 21 is opened sideways so that the exhaust ports 15 of the cooling unit 8 may be viewed. That is, these opened parts are the exhaust ports 15 of the shielding body 25. In such a constitution, the shield body 25 is in contact with the integrated circuit 5 in the pressed down state against the cooling unit 8 by the elastic force due to the slight deformation of the whole body.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a shield structure for an integrated circuit. Many integrated circuits are mounted on a circuit board in an electronic device that constitutes an electronic device, a communication device, and the like, and a predetermined function is performed based on these operations.

Since such an integrated circuit generates heat during its operation, it is necessary to remove this heat generation and maintain it at a predetermined temperature required for operation. As such heat dissipation means, heat is dissipated by a heat conduction plate in contact with the integrated circuit, heat conduction to transfer heat to a radiator, etc., or air is blown throughout the electronic equipment with an electric fan, etc., and the air inside the electronic equipment is replaced. Forced cooling by, or a combination of these is performed.

Electronic devices are being miniaturized and mounted at high density. On the other hand, as a result of promoting low power consumption,
Small signals are processed at high speed. From these points as well, it is possible to prevent the influence of various noise signals from the outside and to prevent the influence on the external electronic equipment due to the leakage from the signal source handled in the electronic equipment to the outside of the electronic equipment. is necessary.

It is more important to prevent leakage to the outside than to prevent the influence of electromagnetic waves from the outside. To this end, such measures are most necessary for an LSI called a CPU (Central Processing Unit) that centrally controls the signal system of the entire circuit in a large number of integrated circuits.

FIG. 6 shows a typical external perspective view of an electronic device to which the present invention is applied. The electronic device 1 is, for example, a portable word processor (document creation device), which has a keyboard 3 on the upper surface of a main body 2 and the keyboard 3
A liquid crystal display unit 4 that can be opened and closed is provided. FIG. 6 is shown with display 4 open for use.

Inside the main body 2, there is a circuit board and many integrated circuits mounted on the circuit board (all are not shown), and signal processing by the integrated circuit is performed in response to input from the keyboard 3. A predetermined display is displayed on the display unit 4.

The integrated circuit 5 mounted and mounted on the internal circuit board is integrated in a central portion (not shown) as shown in the plan view of FIG. 7A and the side view of FIG. A circuit board (chip) is built in, and lead terminals 6 for a large number of signal input / output circuits, power supply circuits, ground circuits, etc.
Is derived, and the package is formed as a package that is entirely flat and molded by synthetic resin molding. The tip portion 7 of the lead terminal 6 is connected and fixed to a circuit pattern on a circuit board (not shown) by soldering.

The integrated circuit as the CPU basically has an external shape similar to that shown in FIG. As a cooling means for radiating heat generated by the operation of the integrated circuit 5 which is the CPU, it is not good practice to form a heat conduction path to use a high density and a narrow mounting space. A small cooling unit 8 as shown in FIG. 8 is being used.

As shown in the external perspective view of FIG. 1A, the cooling unit 8 includes a main body portion 9, a microminiature electric fan 11 provided in the main body portion 9, and a cover portion 12 for covering the main body portion 9. Consists of.

A suction port 13 for cooling air to the electric fan 11 is provided on the upper surface of the cover portion 12, and a duct 14 is extended downward from the suction port 13 so as to surround the electric fan 11. ing. Further, a large number of exhaust ports 15 are opened around the main body 9.

FIG. 1B is a perspective view with the cover portion 12 removed, and a large number of columnar projections 16 are integrally formed from the bottom surface inside the main body portion 9, and in the meantime, the columnar projections 16 are regularly arranged in the vertical and horizontal directions. The passage 17 is formed. Columnar protrusion 1
It can be clearly seen that 6 is formed on the entire surface excluding the electric fan 11 and its periphery. It should be noted that the power supply line to the electric fan 11 and the like are omitted in the drawings for convenience.

In the cooling unit 8, the air sucked from the suction port 13 of the cover portion 12 reaches the inner bottom surface of the main body portion 9 along the duct 14 by the rotation operation of the electric fan 11, and the main body portion passes through the gap around the main body portion 9. 9 is sent out to the peripheral direction. The sent out air is in contact with the periphery of a large number of columnar projections 16 and flows along the passage 17, and is discharged from the exhaust port 15 in the periphery. That is, the exhaust port 15 is an open end of the passage 17 formed in the peripheral surface of the main body 9.

The cooling unit 8 has almost the same size as the package of the integrated circuit 5, is placed on the integrated circuit 5 in a stacked manner, and conducts heat absorption from the bottom surface of the main body 9 to the upper surface of the integrated circuit 5. . The heat conducted and absorbed is transmitted to a large number of columnar protrusions 16, and the air flowing around the columnar protrusions 16 deprives the heat of the electric fan 11, which is an axial fan, to perform forced air cooling.
The height of the cooling unit 8 is extremely thin and does not affect the mounting portion of the electronic device.

In this way, the integrated circuit 5 requiring cooling
It is extremely efficient to directly contact with and to perform local cooling, and the small size of the electric fan 11 is efficient because it consumes less power.

[0015]

2. Description of the Related Art It is necessary to electrically or magnetically shield a circuit portion inside an electronic device 1 as shown in FIG. Is performed by covering the entire internal circuit board or the main part with a suitable metallic component.

According to such a shielding structure, for example,
It is necessary to form an appropriate hole or notch in a connector portion or the like for electrical connection between the internal circuit of the electronic device 1 and the outside.

The cooling unit 8 for cooling the integrated circuit 5 is simply provided by attaching a simple fixing metal fitting to the circuit board, which is pressed against the integrated circuit 5 for heat conduction and does not move. There is.

[0018]

SUMMARY OF THE INVENTION In the above-mentioned structure in which the whole or a substantial part is shielded by the conventional structure, it is expected that many holes or notches are formed in the penetrating portion such as the connector. It was difficult or impossible to obtain such a shielding effect. In such a case, the influence of harmful electromagnetic waves on or from the outside cannot be effectively and reliably prevented.

Shielding the whole or a main part becomes a factor that the structure becomes complicated and the weight of the electronic device 1 cannot be reduced. It has been similarly difficult or impossible to directly hide and shield a part of an integrated circuit because cooling is hindered.

In view of the problems of the prior art as described above, the present invention is to provide a novel cooling structure for an integrated circuit in an electronic device and an effective shielding structure for solving the problems.

[0021]

According to the first aspect of the invention, an integrated circuit mounted on a circuit board and an electric fan are provided. And a cooling unit mounted on the integrated circuit, and a shield having an inlet and an outlet for cooling air to the cooling unit to cover and shield the integrated circuit and the cooling unit. The shield is an integrated circuit shield structure configured to be mounted on the circuit board by pressing the cooling unit.

According to the second invention, an integrated circuit mounted and mounted on a circuit board, a cooling unit having an electric fan and mounted on the integrated circuit, and cooling air for the cooling unit are provided. A shield having an inlet and an outlet to cover and shield the integrated circuit and the cooling unit; and an elastic body interposed between the cooling unit and the shield.
The shield is a shield structure for an integrated circuit configured to be mounted on the circuit board so as to press the cooling unit in cooperation with the elastic body.

[0023]

According to the first aspect of the invention, the shield for covering and pressing both the integrated circuit and the cooling unit mounted thereon has a suction port for cooling air to the electric fan and a cooling unit. Since it has an exhaust port from the unit, it can effectively shield electromagnetic waves without blocking the cooling of the integrated circuit.

According to the second aspect of the invention, the shield for covering and pressing both the integrated circuit and the cooling unit mounted thereon has a suction port for cooling air to the electric fan and the cooling unit. Since it has an exhaust port, the electromagnetic shield can be effectively performed without hindering the cooling of the integrated circuit, and an average pressing action is performed by the pressing in cooperation with the elastic body.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The shield structure of an integrated circuit according to the present invention will be described in detail below with reference to the drawings in the preferred embodiments. Note that the same portions are denoted by the same reference symbols throughout the drawings.

FIG. 1 is a perspective view of an assembled state of one embodiment of the shielding structure for an integrated circuit of the present invention, and is shown in FIG. 2 as a separated state perspective view. In each figure, the integrated circuit 5 and the cooling unit 8 are the same as those shown in FIGS. 7 and 8, and the reference numerals of the respective parts are attached and the detailed description thereof will be omitted. Please refer to.

The tip portions 7 of the lead terminals 6 of the integrated circuit 5 are connected and fixed by soldering to a circuit pattern (not shown) formed on a circuit board 21 such as a printed wiring board. The cooling unit is placed on the package of the integrated circuit 5.

The shield 25 has a suction port 27 formed on the main surface 26 at a position corresponding to the suction port 13 of the cooling unit 8, and a bending 2 for positioning which also functions as a reinforcement on two sides of the pair.
8 and 28, bendings 29 and 29 for reinforcement and positioning on the other two sides, and leg portions 31 are formed at four places at the end portion connected to the bending portions 29 and 29, and the ends thereof are bent to be attached. Holes 32 are formed in each.

The shield 25 is made of a steel plate having a good magnetic permeability, for example, a soft magnetic steel plate, more preferably a high magnetic permeability permalloy, and the surface thereof is a surface treatment having a good conductivity and a rust preventive property, such as Ni. Plated.

Also in the cooling unit 8, according to the embodiment of the present invention, the main body portion 9 and the cover portion 12 are made of an aluminum alloy having a good thermal conductivity, and the surfaces thereof have a good electrical conductivity by contact.

As shown in FIG. 1, the screws 33 are inserted into the holes 32 of the leg portions 31 on the circuit board 21 as shown in FIG. Since the position of the cooling unit 8 is defined by the bending 28, 29 of the four sides of the shield 25, it does not move. The portion indicated by the chain double-dashed line in FIG. 2 will be described later and is not applied to this embodiment.

The sides between the folds 28 and 29 and the circuit board 21 are open so that the exhaust port 15 of the cooling unit 8 can be seen. That is, this open portion is the shield 25.
Of the exhaust port 34.

With the above configuration, the integrated circuit 5 which is a CPU generates heat along with the operation by a predetermined operation of the electronic device. This generated heat is transferred from the main body portion 9 of the cooling unit 8 to the columnar protrusions 16, and the columnar protrusions are generated by blowing the cooling air sucked from the suction port 27 of the shield 25 by the rotation of the electric fan 11 of the cooling unit 8. 16 deprived of cooling airflow.

In this way, the heat of the cooling unit body 9 is lowered and maintained below a predetermined temperature.
The temperature of the integrated circuit 5 is maintained in the same state. The cooling air is discharged from the exhaust port 15 of the cooling unit 8 and the exhaust port 34 of the shield 25.

Since the shield 25 covers the upper surface of the integrated circuit 5 and the cooling unit 8 and the peripheral portion,
These are shielded electrically and magnetically.
The shielding effect is extremely good because the shielding is located at the maximum extent possible.

By further connecting the tip end portion of the leg portion 31 of the shield 25 to the ground pattern of the circuit board 21, the action and effect can be further secured. Furthermore, since both surfaces of the integrated circuit 5 are shielded by connecting to a ground pattern having an area on the back surface or inner layer of the circuit board corresponding to at least the size of the integrated circuit 5, the shielding effect is further improved.

In the above embodiment, the shield 25 attaches and contacts the cooling unit 8 to the integrated circuit 5 in a pressed state, but this is attached and pressed by the elastic force due to a slight deformation of the whole. According to the preferred embodiment of the present invention, the inclusion of an elastic body 35 as in the embodiment shown in FIG. 3 is included.

That is, FIG. 3A is a perspective view, FIG. 3B is a plan view, and FIG. 3C is a side view.
Reference numeral 5 is a leaf spring formed in a frame shape. As a material, a steel plate for springs, a phosphor bronze plate for springs, and other metal plates for springs can be applied. As the surface treatment, a material having good conductivity such as Ni plating is preferable.

Each of the four corners 36 of the frame-shaped elastic body 35 and the central portion 37 of each side is formed in a curved shape so as to have a step. The elastic body 35 is disposed between the upper surface of the cooling unit 8 and the inner surface side of the main surface 26 of the shield 25, as shown by the dotted line in FIG.

With such a structure, the shield 25
Is pressed to elastically deform the step of the elastic body 35, and the elastic restoring force causes the entire cooling unit 8 to be pressed against the integrated circuit 5 on average.

Further, since the conductivity is good, the shield 2
The fact that the cooling unit 8 can be connected to the ground potential of the circuit board 21 through 5 is more reliable than in the case of the previous embodiment, and the cooling unit 8 is used to electrically shield the upper surface of the integrated circuit 5. It will be something that can be made.

The elastic member 35 is used as the shield 2 as described above.
5, the cooling unit 8 is effectively pressed against the integrated circuit 5, and the cooling unit 8 is reliably connected to the ground potential of the circuit board 21 to electrically shield the integrated circuit 5 together with the shield 25. It will increase the effect.

The elastic body 35 is not limited to being bent, but may be a corrugated contact at several points. Further, not only the spring plate material but also conductive rubber such as anisotropic conductive rubber can be applied, and such a material is also included in the present invention.

Next, a second embodiment of the shield according to the present invention will be described with reference to FIG. This shield 41 is
As shown in the figure, a large number of holes 43, which are inlets for cooling air, are provided in a main surface 42 that is a box-shaped upper bottom portion, and similarly, an outlet for cooling air is formed in a peripheral side wall surface 44. A large number of holes 45 are formed in each.

Reinforcing rims 46 are formed on the outer periphery of the lower part, mounting legs 47 are formed at the four corners, and mounting holes 48 are formed in the legs 47. The cooling air suction hole 43 is used as the suction port 13 of the cooling unit 8 shown in FIG.
Sufficient numbers are provided corresponding to the positions. The cooling air exhaust hole 45 is also used as the exhaust port 15 of the cooling unit 8.
A sufficient number is formed corresponding to the positions of.

With the above structure, the shield 2 shown in FIGS.
By applying the shield 41 of the second embodiment in place of 5, the cooling unit 8 and the integrated circuit 5 are completely covered, so that the electromagnetic or electrical shielding can be performed extremely well. The effect is great. Of course, Figure 3
The combined use of the elastic body 35 shown in (5) brings about the same preferable actions and effects.

The fact that the cooling air intake hole 43 and the cooling air exhaust hole 45 of the shield 41 are made to be a large number of relatively small holes makes it difficult for electromagnetic waves to pass therethrough as compared with large window holes. Therefore, by setting the dimensions below the cutoff frequency, a reliable shielded state against electromagnetic waves can be obtained.

The structure for connecting the circuit board 21 to the ground circuit is completely the same as that of the previous embodiment, and its operation and effects are particularly remarkable until it is explained. Not obvious and easy to understand.

The same material and surface treatment as in the previous embodiment can be applied to this shield 41, but the quality is produced by drawing with a press machine because the shape and dimensions are constant. It is possible to obtain a stable product.

When this shield 41 is applied to FIGS. 1 and 2, it is necessary to make the periphery large so as not to come into contact with the lead terminals 6 of the integrated circuit 5.
The lead terminals of the above type are provided on the lower surface of the package in such a shape that they do not protrude to the periphery, and for example, in the case of the PGA type or the like, they can be of a size in contact with the outer periphery of the package.
However, even in the case where the lead terminals 6 are arranged in the periphery such as the integrated circuit 5 in FIG. 7, it is possible to deal with it by performing the two-stage drawing process in which only the perimeter of the relevant part is enlarged, and the skirt is formed as a trapezoid. It is also possible to make it an inclined surface. The above is also advantageous because the press working during manufacturing is easy. Furthermore, a third embodiment of the shield of the present invention will be described below with reference to FIG. FIG. 5 is an external perspective view of the shield 51,
Reinforcing folds 53, 53 on two sides of the pair of main surfaces 52,
Reinforcing folds 54, 54 are similarly formed on the other two sides, and leg portions 55 are formed at four locations on the end portion connected to the folds 54, 54, and the tip ends thereof are bent to form mounting holes 56. It is provided in each.

This shield 51 is also a relatively thin plate made of a steel plate having a good magnetic permeability, for example, a soft magnetic steel plate, more preferably a highly magnetic permalloy. The surface is subjected to a surface treatment with good conductivity and rust prevention, for example, Ni plating.

With the above structure, the shield 51 has the main surface 52 between the upper surface of the integrated circuit 5 and the lower surface of the cooling unit 8, as shown by the chain double-dashed line in FIG. In this way, the screws 33 are attached to the circuit board 21 together with the shield 25 or 41.
Since the shield is provided in contact with the upper surface of the package of the integrated circuit 5 by mounting the shield, the action and effect of the shield become more remarkable.

From the above, the plate thickness of the shield 51 is preferably as thin as possible to achieve the function,
Good results are obtained by lowering the thermal resistance in this part. To this end, it is also possible to apply good results to the contact surfaces of the integrated circuit 5 and the cooling unit 8, for example, by applying thermal grease such as silicone grease or thermal compound.

The present invention is not limited to the above-mentioned embodiments, but the shield is not limited to magnetic metal but may be electrically shielded by non-ferrous metal. In addition, the entire shield can be effectively shielded by disposing the shield shown in FIG. 5 between the integrated circuit 5 and the circuit board 21 in a flat shape. Performing an arbitrary combination of various aspects including the above is extremely effective for such a purpose.

[0055]

As described above in detail, according to the shielding structure of the integrated circuit of the present invention, the integrated circuit mounted and mounted on the circuit board and the cooling unit having the electric fan mounted on the integrated circuit are mounted. On the other hand, by having an inlet and an outlet for cooling air to the cooling unit to cover and press the integrated circuit and the cooling unit, and by attaching a shield that electromagnetically shields the integrated circuit, It is possible to effectively perform electrical or magnetic shielding without impairing cooling.

Since the shielding is performed at the position closest to the integrated circuit, it is suppressed at the part where the harmful electromagnetic waves are generated. Therefore, a conventional shielding metal plate for shielding the inside of the outer casing is not required. And contributes to weight reduction of electrical equipment.

Such a fact improves the performance of the electronic device because it is unlikely to be affected by electrical or magnetic forces from the outside. Even in the other embodiments, the pressing of the shield by the cooperation with the elastic body has an extremely remarkable practical effect such that an averaged press and an electric contact state, a shield state, and the like can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a shield structure for an integrated circuit according to the present invention.

FIG. 2 is a perspective view of the separated state of FIG.

FIG. 3 is an example of an elastic body

FIG. 4 is a perspective view of a shield second embodiment.

FIG. 5 is a perspective view of a shield third embodiment.

FIG. 6 is an external perspective view of an electronic device.

FIG. 7 is a plan view and a side view of an integrated circuit.

FIG. 8 is a perspective view of a cooling unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electronic device 2 Main body 3 Keyboard 4 Display part 5 Integrated circuit 6 Terminal 8 Cooling unit 9 Main body part 11 Electric fan 12 Cover part 13 Inlet port 14 Duct 15 Exhaust port 16 Columnar protrusion 17 Passage 21 Circuit board 25 Shield 26 Main surface 27 Suction port 28,29 Bent 31 Leg part 32 Hole 34 Exhaust port 35 Elastic body 36 Four corners 37 Central part 41 Shield 42 Main surface 43 Cooling air intake hole 44 Side wall surface 45 Cooling air exhaust hole 51 Shield 52 Main surface 53 , 54 Bend 55 Leg 56 Hole

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area H05K 9/00 U

Claims (2)

[Claims] 1. An integrated circuit mounted and mounted on a circuit board, a cooling unit having an electric fan and mounted on the integrated circuit, and an intake port and an exhaust port for cooling air to the cooling unit. And a shield that covers and shields the integrated circuit and the cooling unit, and the shield is configured to be mounted on the circuit board so as to press the cooling unit. Shield structure. 2. An integrated circuit mounted and mounted on a circuit board, a cooling unit having an electric fan and mounted on the integrated circuit, and an inlet and an outlet for cooling air to the cooling unit. A shield for covering and shielding the integrated circuit and the cooling unit, and an elastic body interposed between the cooling unit and the shield. The shield cooperates with the elastic body. A shield structure for an integrated circuit, characterized in that the cooling unit is configured to be mounted on a circuit board so as to be pressed.