JPH05102357A - Pin type heat sink - Google Patents

Abstract

PURPOSE:To improve the heat radiation capacity by drawing up a group of pins, which consist of flat pins the cross sections of which are in the shapes of thin and wide straight angles or ribbons, in a specified number of stages and rows, and arranging them so that the long side of the cross section of each pin forms a specified tilt angle including 0 deg. to the stage direction or row direction. CONSTITUTION:A group of flat pins 2, which consist of flat pins the cross sections of which are in the shapes of thin and wide straight angles or ribbons, are arranged in parallel stages and rows on a heat receiving plate 1 consisting of a thin aluminum or copper plate. Moreover, the tilt angle of each flat pin is made, for example, 0 deg. Accordingly, fierce turbulence never occurs by the rectifying action of the pin plane, and pressure loss becomes small, and current loss convection hardly occurs, either and the current speed drop inside the heat sink becomes extremely small. Hereby, heat radiation capacity improves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a heat sink, and more particularly to a pin type heat sink which is mounted mainly on a heat radiating surface of a small heat generating element and which absorbs the generated heat amount and discharges it into a refrigerant fluid. Concerning the structure of.

[0002]

2. Description of the Related Art A pin-type heat sink as a small radiator for a heat generating element has been noted for its excellent heat radiation performance, and its practical use has been promoted despite the difficulty of its manufacturing method. In particular, a group of small-diameter pins having a pin diameter of about 1.5 mm or less is made to stand upright on the heat receiving plate and arranged in a row, and the distance between the pins is configured to have a high density of about 1.5 mm or less. The pin-type heat sink has extremely high performance, and various industry companies are developing methods for manufacturing such a heat sink.

In such a pin-type heat sink, the refrigerant fluid generates a strong turbulence due to convection between the pins.
This turbulent flow contributed to the outstanding heat dissipation performance. Also in such a pin-type heat sink, according to the same principle as that of the heat transfer coefficient of the outer surface of the cylinder arranged orthogonal to the convection, the smaller the outer diameter of the pin, the better the heat radiation performance. Although such a pin-type heat sink has high performance, it causes problems such as high density of pins due to the occurrence of intense turbulence.

[0004]

[Problems to be Solved by the Invention] The problems to be solved are as follows. (1) The pressure loss of the refrigerant fluid is large due to the severe turbulent flow generated between the pins due to convection, so that the convection in the pin-type heat sink has a large decrease in flow velocity as the number of rows passing therethrough increases. Therefore, the heat radiation performance is not improved when the number of rows is large. As an example, 320 pure copper pins with a diameter of 1 mm and a height of 30 mm are mounted on an aluminum heat receiving plate having a size of 40 mm × 40 mm and a thickness of 1 mm.
The pin-type heat sink as shown in the plan view of FIG. Cooling air having a wind speed of 3 m / s was introduced from the first row side of the pin group while applying a heat amount of 20 W to the heat receiving plate, and changes in the cooling air velocity due to pressure loss, temperature rise of the heat receiving plate, and thermal resistance value were examined. As a result of the measurement, the temperature rise of the heat receiving plate is 15.3 [° C] and the thermal resistance value is 0.77 [° C / W]
The cooling wind velocity flowing out from the 0th row side, that is, the back surface of the heat sink was 1.0 m / s. This temperature rise is 10 ° C lower than that of a heat sink having a normal aluminum plate group,
Although the performance was extremely good, better data could be obtained if the decrease in the wind speed in the heat sink was small. Such a decrease in wind speed requires a large-capacity cooling fan to increase the wind speed when a large number of similar heat sinks are arranged on the same circuit board to cool the heating elements. It was something that

(2) Such an increase in pressure loss reduces the flow rate of convection reaching the row on the outlet side, and increases the flow rate that is lost to both sides of the heat sink. Arrow 8 in FIG. 5 indicates flow convection. Therefore, the high-density pin-type heat sink may rather deteriorate the performance, and the number of rows cannot be increased sufficiently. That is, it is difficult to increase the size and capacity of the pin-type heat sink. Further, for the same reason, when a large number of heat sinks are arranged in series in the flow direction of the refrigerant fluid on the same circuit board, the heat radiation performance may be significantly reduced.

(3) Since the pin-type fin group has extremely good heat dissipation performance, the refrigerant fluid absorbs the amount of heat very efficiently, and the temperature thereof is rapidly raised. Therefore, in the case of stepwise convection, the temperature of the refrigerant fluid is sharply increased each time it passes through the row, and the heat exchange efficiency is drastically lowered toward the downstream row. For this reason also, the high density pin type heat sink has a limit to the number of rows, making it difficult to increase the size and capacity of the heat sink. For the same reason, when a large number of heat sinks are arranged in series on the same circuit board in the flow direction of the refrigerant fluid, the heat radiation performance may be significantly reduced.

The present invention solves the problem that the pressure loss is excessive, and also solves various problems caused by it.
Measure the function of the pin-type heat sink.

[0008]

As means for solving the problems, in the present invention, each pin is formed into a wide flat rectangular pin having a thin cross-sectional shape or a flat pin having a ribbon shape. The pin group is arranged in a row of a predetermined number of rows and a predetermined number of rows, and the long side of each pin has a predetermined inclination angle including 0 degree with respect to the step direction or the row direction. Are arranged.

When such thin-walled flat pins are arranged in an array, turbulent flow generated by convection can be appropriately suppressed, fluid resistance can be reduced, and pressure loss can be reduced by these effects. Also, since it has a function to control the flow direction,
It is possible to prevent the flow rate and the flow rate of the refrigerant, which is lost to the side surface of the heat sink due to the pressure loss, to be reduced to prevent the flow velocity in the heat sink from decreasing. Further, the proper inclination angle controls the discharge direction of the high temperature fluid after the heat exchange, and improves the heat exchange efficiency of the downstream pin group or the downstream heat sink. These combined effects solve all the problems of the conventional pin-type heat sink and add new functions.

[0010]

First Embodiment FIG. 1 is a schematic plan view showing a first embodiment of the present invention. A heat receiving plate 1 is a thin aluminum plate or a thin pure copper plate. The short line 2 shows each pin of the flat pin group, and the cross section of each pin has a wide flat rectangular shape with a small thickness or a ribbon shape. Arrow 3 is the main convection (front flow) of the refrigerant fluid, and arrow 4 is the main convection (back flow). The length of the arrow indicates the magnitude of the flow velocity. The inclination angle of the flat pin of this embodiment is 0 degree. Thus, in the fin group in which thin-walled flat pins are arranged in parallel flat rows, the rectifying action of the pin plane causes a small pressure loss without the occurrence of severe turbulence, and the flat surface of the conventional example shown in FIG. Since there is almost no occurrence of loss convection 8 like the pin group 9 in the figure, the decrease in flow velocity in the heat sink is extremely small. As an example, 240 flat pin groups having a thickness of 0.5 mm, a width of 1.5 mm, and a height of 30 mm are arranged in 20 columns and 12 rows on a 40 mm × 40 mm 1 mm thick aluminum plate as shown in FIG. 2 on the heat receiving plate while flowing at a flow rate of 3 m / s
The amount of heat of 0 W was applied to adjust the temperature rise at the equilibrium temperature of the heat receiving plate, the thermal resistance value, and the change in wind speed. As a result of the measurement, the temperature rise of the heat receiving plate is 13.4 [° C] and the thermal resistance is 0.67 [° C]
/ W], and the flow velocity of the main convection was 3 [m / s] for both the front flow velocity 3 and the back flow velocity 4, as indicated by the length of the arrow, and no reduction in flow velocity occurred. This temperature rise value is 1.9 [° C.], although the number of pins is 8 to 10 as compared with the case of 16 rows and 20 columns in the example of the conventional pin-type heat sink.
Fell. The thermal resistance value was improved by 0.1 [° C / W].

Second Embodiment This embodiment is an embodiment in which each pin of the pin group of the first embodiment is provided with an inclination angle. Figure 2
In the heat receiving plate 1, a boundary surface is shown as an imaginary line 6 which is a surface which stands upright on the plate surface substantially at the center of the main convection (front flow) 3 and the main convection (back flow) 4. With this boundary surface as a boundary, the pin group is divided into two groups, left and right, and the respective groups on one side are provided with different inclination angles. The left and right inclination angles are inclined so as to provide a receding angle or an advancing angle that is substantially symmetrical with respect to the direction of convection with the boundary surface as a symmetry plane.
When a flat pin-type heat sink having an inclination angle as shown in FIG. 2 is arranged during convection as shown in the figure, the convection that flows in is not only the main convection 3 that flows in from the front surface but also the convection that flows in from the side surface of the heat sink. Flows into the heat sink. In such a case, the low temperature inflow convection 5 that flows from the side wall into the main convection 3 whose temperature has risen due to heat reception on the upstream side of the flow.
Are not mixed and the temperature does not rise significantly, and the decrease of the main convection flow velocity due to the pressure loss generated between the pin groups is not compensated by the replenishment of the pressure by the inflow convection 5, and the wind speed reduction does not occur. Is more likely to rise. As an example, each pin in the example of the first embodiment is twisted to give an inclination angle as shown in FIG. 2, and the temperature rise of the heat receiving plate, the thermal resistance value, and the change in the wind speed are changed by supplying exactly the same wind speed and heat quantity. Examined. As a result of actual measurement, the temperature rise of the heat receiving plate was 11.5 ° C, and the thermal resistance value was significantly improved to 0.57 [° C / W]. The flow velocity of the main convection (front flow) 3 was 3 [m / s], whereas the flow velocity of the main convection (back flow) 4 was 3.4 [m / s], which was the same as that of the conventional pin-type heat sink. On the contrary to the decrease in wind speed in the above, the value increased by 0.4 [m / s].

Third Embodiment This embodiment is an embodiment of the present invention in a large heat sink. When the conventional pin-type heat sink is increased in density and size, the heat dissipation efficiency is significantly reduced due to the temperature rise and pressure loss of the refrigerant fluid inside the heat sink, and the effect of adopting the pin-type fin is lost. .. FIG. 3 is a schematic plan view of the heat sink of the present invention which has been enlarged. As shown in the drawing, the boundary surface 6 is provided in the vicinity of the central portion in the longitudinal direction of the heat sink, and the flat pin group is provided with the same inclination angle as in the second embodiment. The present embodiment is characterized in that a pin group of a predetermined number of steps or rows centering on the boundary surface 6 is omitted to form a flow path for the heat transfer fluid. When such a heat sink is arranged in convection, this channel acts as an outlet channel or an inlet channel for the refrigerant fluid. FIG. 3 shows an example of a discharge flow path. When the main convection (front flow) 3 and the main convection (rear flow 4) flow in the direction of the arrow, the side surface of the heat sink is controlled by the convection control action of the flat pin group 2. A large amount of refrigerant fluid flows in as an inflow convection 5. In the present embodiment, most of the main convection and inflow convection in the heat sink flow along the inclination angle of the flat pin group, and the refrigerant fluid heated to a high temperature by heat absorption does not rise above a certain temperature and the pin group is omitted. And then discharged. That is, even if the heat sink is extended in the main convection flow direction and lengthened, the low temperature inflow convection 7 mainly flows from the side surface to the downstream pin group, and the high temperature fluid above the predetermined temperature does not flow in. Further, no matter how long the heat sink is, the distance flowing between the pin groups is constant, and pressure loss above a certain level does not occur. That is, the pin-type heat sink of this embodiment can be arbitrarily increased in size, and therefore, the heat dissipation efficiency does not decrease as in the conventional example.

Although illustration is omitted, in this embodiment, the flow of main convection is in the completely opposite direction, and even if all the arrows in FIG. In that case, the pin group lacking portion serves as an introduction flow path for the low-temperature refrigerant fluid, and the low-temperature fluid flows from that portion into the heat sink along the inclination angle of the flat pin group, and the fluid heated to a high temperature by heat absorption Most are discharged toward the side of the heat sink.

When the convection is caused by a suction fan, the effect of this embodiment is further enhanced by providing the baffle plate 9 shown by the broken line. In that case, even if the flow direction of the main convection is as shown in FIG. 3 or in the opposite direction, there is no flow that passes through the pin group cutouts, and all the convection flows between the flat pin groups. And the heat dissipation efficiency increases.

Fourth Embodiment This embodiment is an embodiment relating to imparting a tilt angle in a flat pin group. FIG. 4 is a partially enlarged view of the front view of this embodiment. In the figure, 1 is a heat receiving plate, and 2-2 is a pin bonding portion. Since it is difficult to vertically bond the flat pin 2 to the heat receiving plate, the flat pin 2 is bent at a right angle and laminated and bonded to the heat receiving plate 1 except the heat radiating portion. Predetermined section 2 from the root of the upright part of each pin 2
-0 are arranged in parallel parallel rows with an inclination angle of 0 degree. The remaining portion of the upright portion of each pin 2 is twisted in a predetermined section 2-1 at a predetermined distance from the root to give a predetermined inclination angle.

The structure of the pin type heat sink having the flat pin group has an advantage of facilitating the arrangement of the pin group having the inclination angle. That is, it is easy to dispose the flat pin group 2-0 having an inclination angle of 0 degree by arranging a flat wire or a ribbon whose both ends are bent at right angles with the both ends bent as pins and adhering them in parallel and parallel to the heat receiving plate. Is. It is also easy to give an inclination angle by twisting each pin 2 of the flat pin group arranged in this way, which is far easier than the structure in which each pin is provided with an inclination angle from the root. Can be manufactured to.

In a heat sink having a flat pin group having an inclined angle, it is difficult for convection to enter the inner row of the pin group, and the inflow amount of convection tends to decrease as a whole. But Figure 4
In the case of the flat pin group as illustrated in Fig. 3, it is easy for convection to flow into the inner row in the portion 2-0 with a tilt angle of 0 degrees left near the root, and convection that flows into the interior from near the root of the pin. Has the effect of replenishing the convection to the portion given the inclination angle with the refrigerant fluid and facilitating the flow, and has the effect of improving the heat dissipation efficiency of the heat sink.

[0018]

As described above, and as can be seen from the operation of each embodiment, the pin type heat sink of the present invention has a thin flat pin and a large surface area, and a fluid for convection parallel to the plane of the flat pin. The resistance is small, the rectification of the flat pin group prevents the occurrence of severe turbulence, and the convection direction control function of the flat pin group prevents flow convection from the side of the heat sink. Remarkably high performance is achieved by the synergistic effect of allowing fluid to flow in.

Further, the convection direction control action and the rectification action of the flat pin group prevent the high temperature fluid from flowing into the downstream side row of the main convection, so that the heat sink can be increased in size and length to any size to increase the capacity. There is also an effect that can be.

Further, when a large number of heat generating elements are mounted on the same circuit board and a heat sink is mounted on each of the heat generating elements for cooling, by applying the heat sink according to the present invention, the convection direction of the flat pin group can be improved. Use control action,
To prevent the high temperature fluid that has passed through the upstream heat sink from flowing into the downstream heat sink and the heating element of the circuit board convection,
The ability to control circuit board convection is considered to be a great advantage.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a first embodiment of a pin-type heat sink of the present invention.

FIG. 2 is a schematic plan view showing a second embodiment of the pin-type heat sink of the present invention.

FIG. 3 is a schematic plan view showing a third embodiment of the pin-type heat sink of the present invention.

FIG. 4 is a partially enlarged side view showing a fourth embodiment of the pin-type heat sink of the present invention.

FIG. 5 is a schematic plan view showing a structural example of a conventional pin-type heat sink.

[Explanation of symbols]

 1 heat receiving plate 2 flat pin group 2-0 pin inclination angle 0 degree part 2-1 pin twisted part 2-2 pin bonded part 3 main convection (front flow) 4 main convection (back flow) 5 inflow convection 6 interface 7 pin Group lacking section 8 Loss of convection

Claims (4)

[Claims] 1. A large number of pins are arranged as a radiation fin group so as to stand upright on a heat receiving plate, and are configured as a pin-type heat sink, and each pin has a wide rectangular cross section whose width is thin or wide. It is formed as a ribbon-shaped flat pin, and the pin group is arranged in a predetermined number of steps and a predetermined number of rows in a step row, and each pin has a long side of its cross section in the step direction or A pin-type heat sink, wherein the pin-type heat sink is arranged with an inclination angle of a predetermined angle including 0 degree with respect to the column direction. 2. The pin group is divided into two groups on both sides of the boundary surface, with a plane perpendicular to the heat receiving plate in the gap between the predetermined rows or in the gap between the predetermined rows in the row arrangement of the pin group as the boundary surface. The inclination angle given to each pin of the group on one side and the inclination angle given to each pin of the group on the other side are defined by the long side of the cross section of each pin above the boundary surface. 2. A tilt angle that gives a receding angle or an advancing angle that is substantially symmetrical with respect to the direction of convection, with the symmetry plane as the symmetry plane.
Pin type heat sink described in. 3. In a row arrangement of pin groups, a pin group of a predetermined number of rows or rows in the vicinity of the central portion of the row or row is abbreviated and arranged, and the heat receiving plate includes the center line of this portion. The pin-type heat sink according to claim 2, wherein a vertical surface is formed as a boundary surface. 4. A predetermined section from the root of each pin of the pin group is arranged in parallel flat rows with a tilt angle of 0 degree, and the remaining portions of each pin are predetermined from the root. 2. A twist angle is given in a predetermined section at a distance of .gamma. To give a tilt angle of a predetermined angle.
Pin type heat sink described in.