Cross Flow Cooling Device for Semiconductor Components

1. Field of Invention

This invention relates generally to a heat dissipating device for cooling semiconductor components which have higher heat dissipation density.

2. Description of the Prior Art

The development of microelectronics or semiconductor industry has brought us CPU, e.g. Pentium, which integrated more than a few millions transistors in one chip. Also, those CPU's plus other IC's can be integrated together into a module called as Multi-Chip Module (MCM). Those CPU or MCM have higher heat dissipation density, which suggests that the heat have to be taken away quickly in certain way, otherwise, reduce the reliability and the life.

For those obvious reasons, a passive cooling structure already on market as shown in FIG. 1. For higher heat dissipating density, a typical active cooling structure is shown in FIG. 2. An axial fan is mounted on the top of a heat sink, the heat sink is mounted in contacted with CPU chip.

Summarized prior arts, there are two major categories to pursuit more efficiency and lower profile fan cooling assembly structure. In the first category, it is to design very slim fan structure with a standard heat sink. Those designs usually lead lower efficiency and Cubic Feet per Minutes (CFM). In second category, it is to design some special heat sinks, which can have a modified axial fan sit into the heat sink. Those designs reduce the dimension in high of cooling assembly as much as the thickness of fan, but sacrifice the conductive heat dissipation of heat sink, since reduce of fin surface area. Same as the first category, it leads lower CFM. In prior arts, there are some controversies among those efforts to reach following three objects at same time: the first is the higher efficiency of air moving away from heat sink; the second is the lower profile of fan and heat sink assembly; the third keeps the higher efficiency of heat sink in both conductive and convective heat transfer. Therefore, all prior arts on cooling CPU have following disadvantages:

(a) All axial fans have hubs, which do nothing with cooling. When set the fan on the top of heat sink to suck or blow air away, the area covered by the hub, almost no air circulation happens there compared with outside of the hub. However, the hub faces often the hottest spot of semiconductor components. The hub contributes nothing of the convective heat transfer.

(b) All axial fans force the air circulation motion in the heat sink in turbulent form, but the heat sink designs do not match the kind of air movement pattern well to maximize the efficiency of convective heat transfer. Inversely, it blocks the air motion, reduces air velocity.

(c) Even many prior arts related to modify the heat sink or the axial fan to reduce the profile of cooling assembly, in any circumstance, anything, such as a plate, can not be set on the top too close to the fan inlet or outlet. Otherwise, no air will get in or out the heat sink. This means that this kind of cooling assembly, an axial fan and a heat sink, have the limitation in some applications, particularly in critical profile limitation.

Accordingly, besides those prior art's pursuit objects, several objects and advantages of the present invention are:

(a) to provide an air flow direction parallel to heat sink fin or air movement pattern, which perfectly matches the structure of heat sink. At same time, it increases the cooling efficiency;

(b) to provide a simple combination structure of a cross flow fan and a heat sink which makes it easily mount and change orientation;

(c) to provide a cooling assembly structure which can be used in various slim designs, such as notebook computer and plug-in module board;

(d) to provide a cooling assembly structure which maximize the cooling efficiency in both convective and conductive heat transfer;

(e) to provide a cooling assembly structure which maximizes the compatibility with those standard heat sinks available on the market;

(f) to minimize the profile of the fan heat sink assembly.

Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.

FIG. 1 shows a typical heat sink as a positive cooling device specially designed for cooling CPU or similar semiconductor components.

FIG. 2 shows an assembly of a heat sink and an axial fan as an active cooling device, which is most popular style for cooling CPU chip according to the prior arts.

FIG. 3 shows another kind assembly of a heat sink and an axial fan as an active cooling device. The heat sink and the axial fan are specially designed to obtain a lower profile.

FIG. 4 is an isometric view of a cross flow fan cooling device for semiconductor components according to the preferred embodiment of the present invention.

FIG. 5 is an exploded view of the cross flow fan cooling device for semiconductor components shown in FIG. 4.

FIG. 6 is a sectional view of the cross flow fan shown in FIG. 4.

10 Pin Fin 12 Axial Fan

14 Fan Hub 16 Fan Blade

18 Radiating Fin 20 Plate Fin

22 Fan Left End 24 Rubber Boot

26 Bearing 28 Fan Right End

30 Cut Off Rod 31 Mounting Hole

34 Motor 33 Motor Shaft

34 Mounting Screw 36 Cross Flow Fan

38 Back of Fan Housing 40 Heat Sink

42 Mounting Slot for Back of Fan Housing 44 Mounting Slot on Cross Flow Fan

46 Fan Air Outlet 48 Blade Rotor

50 Mounting Slot on Heat Sink 52 Blade Rotor Shaft

54 Blade Rotor Hole 56 CPU

58 Mounting Clamps 60 Sharper Edge of Plate Fin

Described herein is a cross flow fan cooling device for semiconductor components. In one embodiment, the present invention provides a device including the cross flow fan and a heat sink for cooling a semiconductor component. The semiconductor component may be a central processing unit ("CPU") or a multi-chip module ("MCM"). The heat sink has one surface physically mounted to a surface of the semiconductor component for dissipating heat from the semiconductor component. The cross flow fan creates directional air flow that flows in parallel to a surface to be cooled and that flows away from the cross flow fan.

FIG. 4 illustrates a cross flow fan cooling device for semiconductor components in accordance with the present invention. The cross flow fan cooling device generally includes a heat sink 40 and a cross flow fan 36. The cross flow fan 36 is mounted to one side of the heat sink 40.

FIGS. 5 and 6 illustrate the cross flow fan 36 in more detail. The cross flow fan 36 comprises a fan left end 22 and a fan right end 28. The fan left end 22 has a hole for holding a rubber boot 24. A bearing 26 that is used for holding one end of a blade rotor 48 sits inside the rubber boot 24. The fan right end 28 has a compartment for housing a motor 32. The cross flow fan 36 further comprises a blade rotor 48, a cut off bar 30 and a back of fan housing 38. One side of the blade rotor 48 has a blade rotor shaft 52 and the diameter of the blade rotor shaft 52 matches the diameter of the bearing 26. The other side of the blade rotor 48 has a blade rotor hole 54 for adopting a motor shaft 33. The fan left end 22 and the fan right end 28 further include mounting slots 42 and mounting holes 31. The mounting slots 42 are designed to match the section size of the back of fan housing 38 for mounting the back of fan housing 38 to the cross flow fan 36. Diameters of the mounting holes 31 match the diameter of the cut off rod 30 for mounting the cut off rod 30 to the cross flow fan 36. The cross flow fan cooling device further includes four mounting clamps 58 for assembling the cross flow fan cooling device to a CPU or a MCM.

FIG. 5 further illustrates the heat sink 40 having a plurality of plate fins 20. One side of the plate fins 20 contains sharper edge to facilitate air flow. The heat sink 40 further includes two mounting slots 50 on two side plate fins for mounting the cross flow fan 36 to the heat sink 40.

In a preferred embodiment, a cross flow fan cooling device containing the heat sink 40 and the cross flow fan 36 is mounted to a semiconductor component or CPU 56, where the cross flaw fan 36 supplies a directional air flow in parallel to a surface of the semiconductor component to be cooled. The cross flaw fan 36 further contains an air outlet and the cut off rod 30. The air outlet is configured to match one side of the heat sink 40 for guiding air flow through surface of the heat sink 40. The cut off rod 30 performs a function to guide air flow in a direction parallel to the surface of the semiconductor component to be cooled. The sharper edges of plate fins 60 are designed to maximize air flow through the heat sink 40. The rubber boot 24 is configured to minimize potential vibration, which may be caused by operation of the blade rotor 48.

In the foregoing detailed description, the cross flow fan cooling device of the present invention has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the present invention. The present specification and figures are accordingly to be regarded as illustrative rather than restrictive.

The present invention have a cross flow fan and a heat sink. The main different from prior arts is that using the cross flow fan obtains a parallel air movement direction relative to heat sink. The air movement direction perfectly matches the heat sink structure to maximize the efficiency of convective heat transfer. Furthermore, the cooling device for semiconductor components has the additional advantages in that:

it provides a simple combination structure of a cross flow fan and a heat sink which make it easily mount and change orientation;

it provides a cooling assembly structure which can be used in various slim designs, such as notebook computer and plug-in module board;

it provides a cooling assembly structure which maximize the cooling efficiency in both convective and conductive heat transfer;

it provides a cooling assembly structure which maximize the compatibility with those standard heat sinks available on the market;

it minimizes the profile of the fan heat sink assembly.

Although the description above contains many specificities, these merely providing illustrations of some of the presently preferred embodiments of this invention. For example, the heat sink can have other shape fins, such as pin fin and spine fin; both the heat sink and the cross flow fan can be made large and longer enough to match larger size of CPU or MCM; different mounting clamps can be used to assemble the cross flow fan cooling device to chips to be cooled etc.

Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.