CN101236936A

CN101236936A - Aluminum heat radiator for semiconductor part

Info

Publication number: CN101236936A
Application number: CNA2007101243674A
Authority: CN
Inventors: 秦彪
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-11-07
Filing date: 2007-11-07
Publication date: 2008-08-06

Abstract

The invention provides a radiator for a semiconductor device, being an improvement based on the prior so-called sun flower type CPU radiator and adopting a centrifugal fan or a multi-level axial fan to improve the pressure of the fan and increase the air traffic flowing through fins and therefore the space between the fins (2), can be reduced, the radiation area of the fins is effectively improved and the convection heat transfer coefficient increases synchronously. Due to the optimization of the fins, the radiator is smaller and compact in dimension, lower in cost but higher in radiation volume.

Description

Aluminum heat radiator for semiconductor part

Affiliated technical field

The present invention relates to the heat dissipation technology field of semiconductor device, particularly by the radiator of forming by the fin and the fan of heat-conducting block, aluminum extruded shaping.

Background technology

Power raising along with semiconductor power device, light emitting semiconductor device, the particularly increase of semiconductor integrated circuit number of transistors, and the increase of operating frequency, caloric value is also along with increase therebetween, and current computer CPU and GPU chip cooling problem have become the obstacle in the computer evolution.For a long time, the heat radiation of electronic device gets the brush-off, technology is in the original heat transfer conceptual phase always, last century 60 is to the seventies, the research of heat transfer technology is very perfect, as long as incite somebody to action achievement in research wherein, adopts correct method, introduce the heat dissipation technology of electronic device, just can obtain significant result.

Existing a kind of cpu chip aluminium radiator: an end face of cylinder is a heat-absorbent surface, and it is close on the radiating surface of chip, stretches out many fins around the side of cylinder, also be referred to as heronsbill, fan is at the other end of cylinder, heat-absorbent surface back to a side, fan and cylinder are coaxial; The heat that chip produces is by the radiating surface of chip and the heat-absorbent surface thermal contact conductance on the cylinder, pass to cylinder, heat mode with heat conduction in cylinder passes to cylindrical side, pass on the fin fans drive air, the fin of flowing through again, in the convective heat transfer mode heat is passed in the air, shed, cylinder only plays conductive force at this, thereby just is referred to as heat-conducting block.This structural advantages has: because fan and cylinder (heat-conducting block) are coaxial, the fans drive air flows along cylindrical side and fin, reduces the existence in air flows dead band in the fin that fan electromotor causes effectively; Because fin and cylinder (heat-conducting block) are to adopt aluminum extruded process forming, fin and heat-conducting block are one, have guaranteed the heat conduction between fin and the cylinder.

But in depth do not analyze diabatic process and air flow process in this radiator during product design now, it all is the single-stage axial fan that adopts on the existing market, do not consider the characteristic relation of its blast of different fans and flow, and the single-stage axial fan that generally adopts on the unclear existing market, its Blade Design is to be purpose with the ventilation, be target to the maximum with air quantity, do not consider blast, thereby when being used for radiator, if fin is intensive, when flow resistance was big, its air quantity descended rapidly, and noise is also big.In the face of ever-increasing CPU caloric value, encrypt fin, only improve airflow pressure from improving rotating speed, when bringing vibrations, noise, bearing life problem, airflow pressure does not effectively improve, because the angle of attack of the relative air stream of the blade in the tube-axial fan has suitable scope, surpass this scope, performance then descends rapidly.That is to say that existing single-stage axial fan is not suitable for the intensive radiator of fin height.

Existing product strengthens, increases the fin size simply in order to improve heat dissipation capacity.Long (the fin root place of rib, by the heat-conducting block place, length to fin point place) reach 30mm, rib length has extended, for not reducing fin efficiency, increase fin thickness, the thick 2mm that reaches of root place rib, gap between the fin is 2～3mm, and rare like this fin density is when area of dissipation is not enough, have to increase fin rib width (distance of heat-conducting block short transverse) and reach 30mm, this just causes the entire radiator size very big, is the device that accounts for the main space size on the computer motherboard, has been the obstacle that reduces in computer size, the densification design.These unreasonable designs also cause the aluminium consumption of radiator big, the cost height.

Summary of the invention

The present invention be directed to above-mentioned radiator and improve, adopt centrifugal fan or multistage axial flow formula fan, improve blast, and then can increase fin density, optimize size, reduce fin thickness, reduce the size of dispelling the heat, reduce material cost, further improve heat dissipation capacity again.

Technical scheme of the present invention is: the main parts of radiator include: heat-conducting block, fin and fan, a smooth heat-absorbent surface is arranged on the heat-conducting block, and be provided with fin all around in the heat-conducting block side, fin is along circumferentially towards a direction bending, fin is an aluminium, adopts expressing technique, whole extrusion molding; Fan be arranged on heat-absorbent surface back to a side, these structures are similar with the cpu heat that now is called as sun fancy.The invention is characterized in: fan is a centrifugal fan, or multistage axial flow formula fan.

Under the situation of same rotating speed and flabellum diameter, the blast of centrifugal fan is higher than the single-stage axial fan, and blast and discharge characteristic are also better; Multistage axial flow formula fan then improve blast by increasing flabellum progression, and rotating speed needn't increase.Thereby the rotating speed of fan, vibration, noise reduce, and the motor bearings life-span increases.Multistage axial flow formula fan is especially adopted in the raising of blast, can obtain higher blast by increasing flabellum progression, just can reduce the gap between the fin, will bring significant effect.

According to thermal conduction study and aerodynamics, can learn: the cross-ventilation among the present invention in the fin conducts heat and belongs to convective heat transfer in the narrow slit, gap size between cross-ventilation thermal transmission coefficient and the fin is inversely proportional to, that is to say that the gap is more little, be fin close more (radiator is compact more), the cross-ventilation thermal transmission coefficient is high more.Thereby reduce the fin gap, and not only having increased heat transfer area, but also improved the cross-ventilation thermal transmission coefficient, effect is to improve doublely.

Best clearance is below the 1mm, but considers the dust pollution problem in when operation, generally not gap design below 1mm, generally get the gap of 1.2～1.5mm, the gap between the fin in the air-conditioning in the air heat exchanger is about 1.5mm.It is considered herein that, it is reasonable value that the fin gap is chosen 2.0mm following, because the fin gap is not necessarily uniform, and the one, the fin gap from the rib root to the rib point is not necessarily even, the 2nd, the gap of each fin is not necessarily even, and fin gap described herein is a mean gap.

Description of drawings

The present invention is further described below in conjunction with drawings and Examples.

Fig. 1 is the basic structure schematic diagram that adopts the radiator of the present invention of centrifugal fan.

Fig. 2, the 3rd, the basic structure schematic diagram of the radiator of the present invention of employing multistage axial flow formula fan.

Fig. 4 is the feature structure schematic diagram of fin and heat-conducting block.

Among the figure, 1, fan, 2, fin, 3, heat-conducting block.

Fig. 1,2,3 basic structures that show radiator of the present invention are formed, heat-absorbent surface is just below heat-conducting block (3), fan (1) is arranged on the upside of heat-conducting block (3), heat-absorbent surface back to a side, fin (2) is round heat-conducting block (3), on the side of heat-conducting block (3), heat-conducting block (3) exceeds (axially) fin (2), be to be convenient to circulation of air, the fin (2) of flowing through equably, because the electronic device that usually is cooled mostly is flat, or radiating surface is greater than the heat-absorbent surface (cross section) of heat-conducting block, and heat-conducting block exceeds the formed space of fin, has just become air flow passage, can eliminate the air flows dead band in the fin like this, these are similar with existing sun fancy cpu heat basic structure.

Fig. 1 is the schematic diagram of the radiator of the present invention of employing centrifugal fan, and the air inlet of fan (1) is facing to fin (2), and air is by fan (1) suction, the fin of flowing through (2).

Fig. 2,3 is the schematic diagram that adopts the radiator of the present invention of multistage (two-stage) tube-axial fan.Multistage axial flow formula fan is not simply two or more tube-axial fans to be superimposed, effect is very low like this, because air through the one-level fan, is driven by electric fan (this is called movable vane), axial velocity is arranged, also has circumferential speed, become helical flow, identical if the back force one wind agitates leaf to turn to, then further increase circumferential speed, promptly increased helical flow, helical flow is unfavorable for improving blast, air quantity.If between the two-stage movable vane, be provided with to stator, as shown in Figure 2, the air directing vane of flowing through, circumferential speed is eliminated, the partial velocity kinetic energy of air converts pressure potential to, air-flow direction is more suitable for the angle of attack of the relative air of back one-level movable vane, and the structure of directing vane is set between this two adjacent movable vanes, is the normal structure of multistage axial flow formula blower fan, air compressor machine.Also can adopt another kind of structure, two successive stages movable vane switched in opposite, as shown in Figure 3, back one-level movable vane not only plays a part further driving air, provides kinetic energy to air, also play a part directing vane, diffusion converts kinetic energy to pressure potential, eliminate circumferential speed and helical flow and increase, effectively improve blast, the air quantity of fan.

Fig. 4 is the feature vertical view of fin and heat-conducting block, show a feature, towards a direction bending, so crooked fin makes the difference in the gap that fin root place and point are located reduce to fin (2) along circumferentially, can design and manufacture gap unanimity from root to the point place.No matter be the gap between each fin, still gap from root to the point place, uniformity is wanted in the gap as far as possible, and this is extremely important, can guarantee that like this air fin of flowing through is even, helps the integral heat sink face and is not fully exerted.If gap, root place is little, the Jian Chu gap is big, then flow through by point place air capacity big, but because the thermal conduction resistance in the fin, the temperature at fin point place is lower than the temperature at root place, thereby heat radiation advantage in root place can not get effective utilization.The gap evenly also has an advantage to be: identical rib is long, identical fin number, and promptly total fin area is identical, and under the identical situation of heat-conducting block external diameter, the radiator external diameter is little, and is compacter.Thereby the present invention choose the ratio in fin Jian Chu gap and gap, root place must not be greater than 1.5.

Vane drive air movement in the tube-axial fan, producing has circumferential component velocity, centrifugal outside.The fan rotation direction is opposite with the fin bending direction, then the circumferential component velocity of air is also with regard to anti-the bending direction of fin, air through fan directly blows in fin curved interior (entad side), the circumferential component velocity of air and the inboard of fin bending are less than 90 °, thereby fin has centripetal thrust force to air, help increasing air mass flow like this, help heat radiation and improve by fin root place.

Rib width is excessive, the flow through distance of fin of air, and flow resistance is big, and the air capacity of flowing through reduces, and is unfavorable for improving heat loss through convection; Rib width strengthens again, and then the height of heat-conducting block increases, and the heat conduction in the heat-conducting block is apart from increasing, and thermal conduction resistance increases, and is unfavorable for that heat radiation improves.To cpu heat, if rib width is 25mm, heat-conducting block just should have the 30mm height, and this has been very high value, and rib width is chosen and is not more than 25mm is reasonable value.If the convective heat transfer face is not enough, had better not select to improve rib width, should select to reduce fin gap (encryption fin) and increase the heat-conducting block diameter, increase the fin number.

According to thermal conduction study, fin efficiency is the function of mL, descend along with the increase of mL, be the functional relation that curve descends, mL is 1.0 o'clock, the fin efficiency decrease speed is the fastest, for straight rib (involved in the present invention), this moment, fin efficiency was roughly 76%, and the value of getting mL when generally designing is not more than 1.0, wherein L is rib long (the rib root is to the length of rib point), and the square root of the thickness of m and fin is inversely proportional to.If fin thickness reduces 4 times, the long L of rib reduces 2 times, and then fin efficiency is constant.Illustrate to reduce fin thickness, can reduce the fin material usage effectively, fin (aluminium) thickness in the air heat exchanger (evaporator and condenser) in the existing air-conditioning is reduced to below the 0.1mm.

It is very meaningful to reduce rib thickness: reduce material, promptly reduce cost, reduce the thick shared circulation area of rib, the space of vacating can increase the fin number, has promptly increased area of dissipation.Be subjected to the restriction of aluminum extruded technology, can not produce the thick fin of 0.1mm, but the thick fin of 2.0mm is very irrational.The present invention proposes, and gets fin thickness and is not more than 0.8mm for rationally, according to heat transfer theory, it is thin even more ideal that fin manufactures thick, sharp place, root place, and expressing technique just can produce this fin, and fin thickness set forth above is not more than 0.8mm, should be that average fin thickness is not more than 0.8mm.Fin thickness reduces, and not low for guaranteeing fin efficiency, rib length can not be oversize, it is considered herein that rib is failed to grow up to be advisable in 25mm.

Claims

1, a kind of radiator that is used to cool off semiconductor device, include: heat-conducting block (3), fin (2) and fan (1), one smooth heat-absorbent surface is arranged on the heat-conducting block (3), and fin (2) is around heat-conducting block (3) side, along circumferentially towards a direction bending, fin (2) is an aluminium, adopt expressing technique, whole extrusion molding, fan (1) be arranged on heat-absorbent surface back to a side, it is characterized in that: fan (1) is a centrifugal fan, or multistage axial flow formula fan.

2, radiator according to claim 1 is characterized in that: the rib of fin is failed to grow up in 25mm, and the rib width of fin is not more than 25mm, and the average thickness of fin is not more than 0.8mm, and the mean gap between the fin is below the 2.0mm.

3, radiator according to claim 2 is characterized in that: the ratio in fin (2) Jian Chu gap and gap, root place is not more than 1.5.

4, according to claim 1 or 2 or 3 described radiators, it is characterized in that: the bending direction of fan (1) rotation direction and fin (2) is opposite.