CN111902024A - Heat dissipation method and heat dissipation structure of space high-heat-consumption photoelectric equipment - Google Patents
Heat dissipation method and heat dissipation structure of space high-heat-consumption photoelectric equipment Download PDFInfo
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- CN111902024A CN111902024A CN202010760659.2A CN202010760659A CN111902024A CN 111902024 A CN111902024 A CN 111902024A CN 202010760659 A CN202010760659 A CN 202010760659A CN 111902024 A CN111902024 A CN 111902024A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2039—Modifications to facilitate cooling, ventilating, or heating characterised by the heat transfer by conduction from the heat generating element to a dissipating body
- H05K7/205—Heat-dissipating body thermally connected to heat generating element via thermal paths through printed circuit board [PCB]
Abstract
The invention relates to a heat dissipation method and a heat dissipation structure of space high-heat-consumption photoelectric equipment, which comprises the following steps of (1) taking a case as a main path for heat dissipation, and carrying out optimized heat dissipation design on the case; (2) dividing the functional modules packaged into an integrated structure into a common functional module and a functional module with a precise temperature control requirement, and performing optimized heat dissipation design on the functional modules; (3) calculating the equivalent thermal conductivity of the PCB, performing the optimized heat dissipation design of the PCB installed in the computer case, strengthening the conduction heat dissipation path between the PCB and the case shell, and optimizing the layout of high-heat-generation components; (4) and the heat dissipation of the high-heating element on the PCB is enhanced, so that the heat dissipation effect of the high-heating element is improved. Aiming at the conditions that the modern electronic equipment has higher and higher integration level, components have larger and larger heat flows, limited layout and installation space and large use restriction conditions, the invention is suitable for the thermal design task of heat dissipation and temperature precise control of high-heat-flow devices with random space distribution layout and limited installation space.
Description
Technical Field
The invention relates to a heat dissipation method and a heat dissipation structure of space high-heat-consumption photoelectric equipment, and belongs to the technical field of space equipment thermal design.
Background
Along with the rapid development of a load technology, the integration level of electronic equipment is higher and higher, the performance requirement is also higher and higher, the structural size of an electronic device in the equipment is smaller and smaller, the power consumption is also higher and higher, and the difficulty of heat dissipation design and temperature control of the device is obviously increased. If the thermal design method is improper, the performance index and the service life of the equipment are seriously affected, especially the space electronic equipment, such as the electronic equipment used by the GEO spacecraft, generally needs to operate in an in-orbit space for more than 15 years, and the reliability of the thermal design method is very important. In electronic products, the effects of high temperature on the electronic products include degradation of insulation properties, damage of components, thermal aging of materials, cracking of low-melting-point welds, and falling off of welds, resulting in a decrease in the performance of the entire product to complete failure. Statistically, 55% of electronic equipment failures are caused by high temperature, and as the temperature rises, the failure rate increases exponentially. The electronic components are basic products of electronic and electrical systems, the temperature of the electronic components is an important factor influencing the working reliability of the electronic equipment, and therefore, the electronic equipment and the components are subjected to thermal design, the temperature of the selected electronic components is controlled within a specified allowable working temperature range, and the method is a technical means for effectively ensuring and improving the reliability of the electronic equipment and the components.
The main heat dissipation path of the electronic equipment is to dissipate heat to the outside by means of an equipment case, a common thermal design method is that the heat dissipation of components is conducted to a case shell (a PCB is mechanically connected with the case shell) through a PCB (printed circuit board) mounted on the electronic equipment, the PCB mainly comprises glass fiber reinforced plastics or ceramics, the heat conductivity is low, the heat transfer effect is limited, for high-heat-consumption and high-heat-flow devices, heat dissipation is strengthened by adopting a heat-conducting metal strip, a micro heat pipe and the like to lap-joint the components and the case shell except for heat dissipation of the PCB, and the heat dissipation design brings strong limiting conditions such as layout, enough mounting space and the like, and is not suitable for precise temperature range control. In summary, modern electronic equipment has higher and higher integration level, larger and larger heat flow of components, and very limited layout and installation space, and the existing thermal design technology of electronic equipment has large use constraint conditions and high design cost, cannot meet the thermal design task requirements of heat dissipation and temperature precision control of high heat flow devices with randomly distributed layout in space and limited installation space, and needs to develop a new efficient thermal design method urgently.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method overcomes the defects of the prior art, provides a heat dissipation method of space high-heat-consumption photoelectric equipment, and aims to overcome the defects and defects that the existing method is not suitable for random layout heat dissipation and precise temperature control of high-heat-flow components.
The technical scheme adopted by the invention is as follows:
a heat dissipation method of space high heat consumption photoelectric equipment comprises the following steps:
(1) the case is used as a main path for heat dissipation of the equipment function module, the PCB and the components, and optimized heat dissipation design of the case is carried out;
(2) dividing the functional modules packaged into an integrated structure into a common functional module and a functional module with a precise temperature control requirement, and performing optimized heat dissipation design on the functional modules packaged into an integrated structure in the case;
(3) calculating the equivalent thermal conductivity of the PCB, performing the optimized heat dissipation design of the PCB installed in the computer case, strengthening the conduction heat dissipation path between the PCB and the case shell, and optimizing the layout of high-heat-generation components;
(4) and the heat dissipation of the high-heating element on the PCB is enhanced, so that the heat dissipation effect of the high-heating element is improved.
Further, carry out the optimization heat dissipation design of quick-witted case, specifically do: the casing structure of the case comprises a bottom plate, side plates and a cover plate which are all made of aluminum alloy materials, the bottom plate and the side plates are connected together and milled into an integral structure, the thermal resistance of a heat transfer path is reduced, and the cover plate is fixed on the upper sides of the side plates and used for sealing the case; the mounting surfaces of the inner side and the outer side of the chassis bottom plate are full contact surfaces without weight reduction grooves, and the surface of the chassis is subjected to high-emissivity surface treatment to strengthen space radiation heat dissipation.
Further, the surface treatment of the surface of the chassis with high emissivity refers to spraying black paint or black anodizing; the wall thickness of the case is not less than 2.5mm, and the flatness error of the installation surface is required to be less than 0.1mm within the range of any 100mm multiplied by 100 mm.
Further, carry out the interior optimization heat dissipation design who encapsulates the functional module as an organic whole structure of quick-witted case, specifically do:
and for the common functional module, the common functional module is directly arranged and installed on the installation surface at the inner side of the chassis bottom plate, heat conducting filler is filled between the common functional module and the installation surface at the inner side of the chassis to strengthen contact heat transfer, and the common functional module directly radiates heat through the chassis.
Furthermore, for the functional module with the requirement of precise temperature control, a thermoelectric refrigerator is firstly installed on the installation surface on the inner side of the bottom plate of the machine box, then the functional module with the requirement of precise temperature control is fixed on the thermoelectric refrigerator, and the thermoelectric refrigerator is used for carrying out bidirectional heat flow control of heating or refrigerating on the functional module with the requirement of precise temperature control, so that precise control of a temperature interval is realized; the functional module with the requirement of precise temperature control is fixedly arranged on the thermoelectric refrigerator through screws or metal hoops, the thermoelectric refrigerator is arranged on the mounting surface on the inner side of the bottom plate of the machine box through the screws, all contact surfaces are ensured to be in close contact, and heat conducting fillers are filled among all the mounting surfaces to strengthen contact heat transfer.
Further, the common functional module is a functional module with the lowest working temperature lower than 0 ℃ and the highest working temperature higher than 50 ℃, the functional module with the requirement of precise temperature control is a laser module, and the working temperature range of the functional module is 35 +/-1 ℃.
Further, the optimized heat dissipation design of the PCB installed in the engine box specifically comprises the following steps:
the number of copper-clad layers of the PCB and the thickness of the copper-clad layer are increased, the equivalent thermal conductivity of the PCB is improved, the copper-clad layer extends to the edge of the circuit board mounting frame, and copper is clad on the outer surface of the circuit board mounting frame; increasing the local copper-clad area and the thickness of a copper-clad layer in a high-heating component mounting area; the high-heating element is an element with heat consumption more than or equal to 0.3W;
the heat transfer is carried out between the components and the PCB through the contact of the pins of the components, when the requirement of electric fitting is met, the length of the pins of the components is as short as possible, the conduction thermal resistance is reduced, heat-conducting fillers are filled in the contact surfaces between the components and the PCB, the width of the contact surfaces between the installation frame of the PCB and the casing of the case is not less than 5mm, the heat-conducting fillers are filled in the contact surfaces, and the heat-conducting fillers are installed and fixed by screws, so that the conduction heat dissipation path between the PCB and the casing of the;
when the components are arranged, the high-heat-generating components are arranged at the edge of the PCB, so that a heat transfer path between the high-heat-generating components and the case shell is shortened; meanwhile, the high-heating components are distributed, so that the heat source concentration is avoided.
Further, the equivalent thermal conductivity of the PCB board is calculated as follows:
in the formula, λEquivalent weightIs the equivalent thermal conductivity, lambda, of the PCBCuIs the thermal conductivity, lambda, of copper in the copper-clad layerPCBFor thermal conductivity of PCB plate material, HCu,iThe thickness of the ith copper-clad layer of the PCB is HPCB,iThe thickness of an ith plate interlayer of the PCB is set; pCu,iThe copper-clad area percentage of the ith copper-clad layer of the PCB is shown; n is the total number of copper layers coated on the PCB; and m is the total number of layers of the PCB plate interlayer.
Further, carry out the heat dissipation of high heating element spare on the PCB board and strengthen the design, specifically do:
the high-heating components on the PCB are reinforced and radiated by the radiating panel, the radiating panel is mechanically connected with the case shell by screws, and heat-conducting fillers are filled between contact surfaces; according to the spatial geometric distribution position of the high-heating element on the PCB, a structural boss is arranged on the heat dissipation panel corresponding to the projection position, namely, the structural boss with the adaptive height corresponding to the geometric position of the high-heating element is arranged on the heat dissipation panel, so that the structural boss is in surface contact with the heating surface of the element; a heat-conducting elastic pad is arranged between the structural boss and the contact surface of the device, and the heat-conducting elastic pad is elastically compressed to ensure that the structural boss, the device and the device are in close contact, so that the thermal contact resistance is reduced; the PCB board around the high heating device and the heat dissipation panel are uniformly provided with a proper number of screw installation interfaces, and the heat dissipation panel structure boss, the heat conduction elastic pad and the device heating surface are pressed tightly again through screws.
Furthermore, the heat dissipation panel is made of an aluminum alloy 6063 material, the width of a connecting contact surface between the heat dissipation panel and the case shell is not less than 5mm, and the thickness of the compressed heat conduction elastic pad is less than 0.3 mm.
The invention also provides a heat dissipation structure of the space high-heat-consumption photoelectric equipment, which comprises the following components: the device comprises a case shell, a common function module, a thermoelectric refrigerator, a precise temperature control module, a PCB (printed circuit board), common components, high-heating components, a heat conduction elastic pad and a heat dissipation panel;
the casing of the case comprises a bottom plate, side plates and a cover plate which are all made of aluminum alloy materials, the bottom plate and the side plates are connected together and milled into an integral structure, the thermal resistance of a heat transfer path is reduced, and the cover plate is fixed on the upper sides of the side plates and used for sealing the case; mounting surfaces on the inner side and the outer side of the chassis bottom plate are full contact surfaces without weight reduction grooves, and the surface of the chassis is subjected to high-emissivity surface treatment to strengthen space radiation heat dissipation;
the common functional module is directly arranged on the mounting surface on the inner side of the chassis base plate, heat dissipation is directly carried out through the chassis, and heat conducting fillers are filled between the common functional module and the mounting surface on the inner side of the chassis to strengthen contact heat transfer;
the thermoelectric refrigerator is fixedly arranged on the mounting surface on the inner side of the bottom plate of the machine box, the precise temperature control module is arranged on the thermoelectric refrigerator, and the thermoelectric refrigerator is used for performing bidirectional heat flow control on heating or refrigerating of the precise temperature control module to realize precise control of a temperature interval; the precise temperature control module is fixedly arranged on the thermoelectric refrigerator through screws or metal hoops, the thermoelectric refrigerator is arranged on the mounting surface on the inner side of the bottom plate of the refrigerator through screws, all contact surfaces are ensured to be in close contact, and heat-conducting fillers are filled between the mounting surfaces to strengthen contact heat transfer;
the PCB is arranged in the case shell, a copper-clad layer of the PCB extends to the edge of a circuit board mounting frame, copper is coated on the outer surface of the circuit board mounting frame, and the region of the PCB where the high-heating element is arranged is subjected to treatment of locally increasing the copper-clad area and increasing the thickness of the copper-clad layer;
the common components and the high-heating components are arranged on the PCB and are in contact heat transfer with the PCB through component pins, heat-conducting fillers are filled in contact surfaces between the components and the PCB, the width of the contact surfaces between a PCB mounting frame and a case shell is not less than 5mm, the heat-conducting fillers are filled between the contact surfaces, and the components and the PCB are mounted and fixed by screws;
the high-heat-generating components are arranged at the edge of the PCB, so that a heat transfer path between the high-heat-generating components and the case shell is shortened; meanwhile, the high-heating components are distributed, so that the heat source concentration is avoided;
the high-heating components on the PCB are reinforced and radiated through the radiating panel, the radiating panel is mechanically connected with the case shell through screws, and heat-conducting fillers are filled between contact surfaces; according to the spatial geometric distribution position of the high-heating element on the PCB, a structural boss is arranged on the heat dissipation panel corresponding to the projection position, so that the structural boss is in surface contact with the heating surface of the high-heating element; a heat-conducting elastic pad is arranged between the structural boss and the contact surface of the high-heating component, and the heat-conducting elastic pad is elastically compressed to ensure that the structural boss, the high-heating component and the high-heating component are in close contact, so that the thermal contact resistance is reduced; the PCB board around the high-heating device and the heat dissipation panel are uniformly provided with screw mounting interfaces, and the heat dissipation panel structure boss, the heat conduction elastic pad and the high-heating device are compressed again through screws to contact the heat dissipation panel structure boss, the heat conduction elastic pad and the high-heating device heating surface.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention provides a thermal design method of a high-heat-flow device of equipment in a space environment, which is good in universality and widely applicable to thermal design of space equipment.
(2) The invention provides a heat dissipation structure design, can effectively solve the difficult problems of heat collection, transmission and dissipation of high heat flow devices which are randomly distributed in space at multiple points, and has the advantages of strong heat transfer capacity, simple structure assembly, high reliability, small design constraint, low cost and the like.
(3) The thermoelectric cooler (TEC) technology provided by the invention solves the problem of precise temperature control of modules and components with high temperature precision requirements, can realize precise control of a temperature range of 35 +/-1 ℃, and has the advantages of high temperature control precision, low power consumption, small volume, light weight, good use and easy use. Meanwhile, the design interface is simplified, and the thermal design resource is obviously saved.
(4) The module classification heat dissipation design method provided by the invention adopts corresponding heat control measures according to the module temperature interval, and can obviously save the design cost.
(5) The heat dissipation design method provided by the invention is based on passive heat control technologies such as material selection, heat control coating, structural design and the like, has high heat dissipation efficiency and high reliability, and is suitable for heat dissipation design of long-life space equipment.
Drawings
FIG. 1 is a schematic diagram of a heat dissipation design of a space high heat dissipation optoelectronic device according to the present invention;
fig. 2 is a flow chart of a heat dissipation method of the space high heat consumption photoelectric device of the present invention.
Detailed Description
Aiming at the problems of heat dissipation and precise temperature control of high heat flow devices randomly distributed in space equipment, a thermal design method is provided, and an electromechanical and thermal integrated design principle is considered, as shown in fig. 2, the specific method is as follows:
(1) the case is used as a main path for heat dissipation of the equipment function module, the PCB and the components, and optimized heat dissipation design of the case is carried out;
the casing of the case is made of a material with low specific gravity and high thermal conductivity, and the case is made of an aluminum alloy material. The casing structure of the case comprises a bottom plate, side plates and a cover plate, wherein the bottom plate and the side plates are connected together and milled into an integral structure, so that the thermal resistance of a heat transfer path is reduced, and the cover plate is fixed on the upper sides of the side plates and used for sealing the case; the mounting surfaces of the inner side and the outer side of the chassis bottom plate are full contact surfaces without weight reduction grooves, and the surface of the chassis is subjected to high-emissivity surface treatment to strengthen space radiation heat dissipation. The wall thickness of the case is generally not less than 2.5mm, and the flatness error of the mounting surfaces on the inner side and the outer side is required to be less than 0.1mm within the range of any 100mm multiplied by 100 mm. The surface of the case is subjected to high-emissivity surface treatment (black paint spraying or black anodizing) to strengthen spatial radiation heat dissipation.
(2) The functional modules packaged into an integrated structure are divided into a common functional module and a functional module with a precise temperature control requirement, and the optimized heat dissipation design of the functional modules packaged into an integrated structure in the case is carried out.
And for the common functional module, the common functional module is directly arranged and installed on the installation surface at the inner side of the chassis bottom plate, heat conducting filler is filled between the common functional module and the installation surface at the inner side of the chassis to strengthen contact heat transfer, and the common functional module directly radiates heat through the chassis.
For the functional module with the requirement of precise temperature control, a thermoelectric cooler (TEC) is firstly installed on the installation surface on the inner side of the bottom plate of the machine box, then the functional module with the requirement of precise temperature control is fixed on the TEC, and the thermoelectric cooler is used for carrying out bidirectional heat flow control of heating or refrigerating on the functional module with the requirement of precise temperature control, so that precise control of a temperature interval is realized; the functional module with the requirement of precise temperature control is fixedly arranged on the thermoelectric refrigerator through screws or metal hoops, the thermoelectric refrigerator is arranged on the mounting surface on the inner side of the bottom plate of the machine box through the screws, all contact surfaces are ensured to be in close contact, and heat conducting fillers are filled among all the mounting surfaces to strengthen contact heat transfer.
The temperature of the whole working environment of the photoelectric equipment is 0-50 ℃, the common function module in the case generally refers to a working temperature range which is 0-50 ℃ larger than the temperature range of the whole working environment of the photoelectric equipment, namely the common function module refers to a function module with a wider working range, such as the lowest working temperature is lower than 0 ℃ and the highest working temperature is higher than 50 ℃, the function module with the requirement of precise temperature control refers to a Laser (LD) module, and the working temperature range is very strict and is generally 35 +/-1 ℃.
(3) Calculating the equivalent thermal conductivity of the PCB, performing the optimized heat dissipation design of the PCB installed in the computer case, strengthening the conduction heat dissipation path between the PCB and the case shell, and optimizing the layout of high-heat-generation components;
the components and parts transmit heat to the case shell by means of the PCB installed on the components and parts, the number of copper-clad layers and the thickness of the copper-clad layer of the PCB are increased on the premise of meeting the electrical performance design, the equivalent heat conductivity of the PCB is improved, the copper-clad layer extends to the edge of the circuit board installation frame, and copper is clad on the outer surface of the circuit board installation frame. Particularly, the local copper-clad area or the thickness of a copper-clad layer in a mounting area of the high-heating component (more than or equal to 0.3W) is enhanced, and the copper-clad layer extends to a circuit board mounting frame. The heat conduction and dissipation path between the PCB and the case shell is strengthened by adopting screw installation and fixation and filling heat conduction fillers (coating heat conduction grease) between the contact surfaces. The components are reasonably distributed, and when the components are distributed, the components with high power and high heat productivity are distributed at the edge of the PCB, so that the heat transfer path between the high-heat-production components and the case shell is shortened. The high-power components are distributed as dispersedly as possible, so that the heat source concentration is avoided, and the layout of the high-heating components is optimized.
The equivalent thermal conductivity of the PCB board is calculated as follows:
in the formula, λEquivalent weightPCB equivalent thermal conductivity, unit: w/(m.k);
λCuthermal conductivity of copper-clad layer, unit: w/(m.k);
λPCBthermal conductivity of PCB board, unit: w/(m.k);
HCu,ithickness of ith copper-clad layer of PCB board, unit: m;
HPCB,ithickness of the interlayer of the ith board of the PCB, unit: m;
PCu,ithe percentage of the copper-clad area of the ith copper-clad layer of the PCB is as follows: percent;
n-total number of copper-clad layers of PCB board, unit: a layer;
m-total number of layers of the interlayer of the PCB board, unit: and (3) a layer.
(4) And the heat dissipation of the high-heating element on the PCB is enhanced, so that the heat dissipation effect of the high-heating element is improved.
Aiming at the components with high heat consumption and high heat flow which are randomly distributed on the PCB, a special radiating panel is designed to be used as a heat collecting and transmitting device, so that the remote high-efficiency heat dissipation of the components with high heat consumption and high heat flow which are randomly distributed in space is realized.
The specific thermal design is as follows: a heat dissipation panel is designed on the heating surface of a component of a PCB and is formed by processing low-specific-gravity and high-heat-conductivity aluminum alloy (6063) materials, the heat dissipation panel is mechanically connected with a case shell structure through screws, the width of a connecting contact surface is not less than 5mm, and heat conduction fillers are filled between the contact surfaces. According to the spatial geometric distribution position of the high-heating element on the PCB, the structural boss shaping design is carried out on the radiating panel corresponding to the projection position, namely, the structural boss with the adaptive height corresponding to the geometric position of the high-heating element is designed on the radiating panel and is in surface contact with the heating surface of the element, and the detailed structure is shown in figure 1. Considering the design of processing assembly clearance, a heat-conducting elastic Pad (Sil-Pad 2000 series is recommended to be selected) with the thickness of less than 0.3mm (after compression) is filled between the structural boss and the contact surface of the device, and the heat-conducting elastic Pad is elastically compressed to ensure the close contact of the three, so that the thermal contact resistance is reduced.
The PCB board around the high heating device and the heat radiation panel are uniformly provided with a proper number of screw installation interfaces, and the heat radiation structure boss, the heat conduction elastic pad and the device heating surface are tightly contacted with each other again through screws. Lightening holes or grooves can be formed in the non-main heat transfer path of the heat dissipation panel according to lightening requirements.
According to the heat dissipation method designed above, a heat dissipation structure of a space high heat consumption photovoltaic device is implemented, as shown in fig. 1, including: the device comprises a case shell 1, a common function module 2, a thermoelectric refrigerator 3, a precise temperature control module 4, a PCB 5, a common component 6, a high-heating component 7, a heat-conducting elastic pad 8 and a heat-radiating panel 9;
the chassis shell 1 comprises a bottom plate, side plates and a cover plate which are all made of aluminum alloy materials, the bottom plate and the side plates are connected together and milled into an integral structure, the thermal resistance of a heat transfer path is reduced, and the cover plate is fixed on the upper sides of the side plates and used for sealing the chassis; mounting surfaces on the inner side and the outer side of the chassis bottom plate are full contact surfaces without weight reduction grooves, and the surface of the chassis is subjected to high-emissivity surface treatment to strengthen space radiation heat dissipation;
the common functional module 2 is directly arranged on the mounting surface on the inner side of the chassis bottom plate, heat dissipation is directly carried out through the chassis, and heat conducting fillers are filled between the common functional module and the mounting surface on the inner side of the chassis to strengthen contact heat transfer;
the thermoelectric refrigerator 3 is fixedly arranged on the mounting surface on the inner side of the bottom plate of the machine box, the precise temperature control module 4 is arranged on the thermoelectric refrigerator 3, and the thermoelectric refrigerator 3 is used for carrying out bidirectional heat flow control on heating or refrigerating of the precise temperature control module 4 so as to realize precise control of a temperature interval; the precise temperature control module 4 is fixedly arranged on the thermoelectric refrigerator 3 through screws or metal hoops, the thermoelectric refrigerator 3 is arranged on the mounting surface on the inner side of the bottom plate of the machine box through screws, all contact surfaces are ensured to be in close contact, and heat conducting fillers are filled between the mounting surfaces to strengthen contact heat transfer;
the PCB 5 is arranged in the case shell 1, a copper-clad layer of the PCB 5 extends to the edge of a circuit board mounting frame, copper is coated on the outer surface of the circuit board mounting frame, and the region of the PCB 5 where high-heating components are arranged is subjected to treatment of locally increasing the copper-clad area and increasing the thickness of the copper-clad layer;
the common component 6 and the high-heating component 7 are arranged on the PCB 5 and are in contact heat transfer with the PCB 5 through component pins, heat-conducting fillers are filled in contact surfaces between the components and the PCB, the width of the contact surfaces between a mounting frame of the PCB 5 and a housing of the chassis is not less than 5mm, the heat-conducting fillers are filled in the contact surfaces, and the contact surfaces are mounted and fixed by screws;
the high-heat-generation component 7 is arranged at the edge of the PCB 5, so that a heat transfer path between the high-heat-generation component 7 and the chassis shell 1 is shortened; meanwhile, the high-heating components 7 are distributed, so that the heat source concentration is avoided;
the high-heating component 7 on the PCB is reinforced and radiated through the radiating panel 9, the radiating panel 9 and the case shell 1 are mechanically connected through screws, and heat conducting fillers are filled between contact surfaces; according to the space geometric distribution position of the high heating element 7 on the PCB, a structure boss is arranged on the heat dissipation panel 9 corresponding to the projection position, so that the structure boss is in surface contact with the heating surface of the high heating element 7; a heat conduction elastic pad 8 is arranged between the contact surface of the structural boss and the high-heating component 7, and the heat conduction elastic pad 8 is elastically compressed to ensure that the three are in close contact, so that the thermal contact resistance is reduced; screw installation interfaces are uniformly distributed on the PCB 5 and the heat dissipation panel 9 around the high-heat-generation device 7, and the contact among the boss of the structure of the heat dissipation panel 9, the heat conduction elastic pad 8 and the heat generation surface of the high-heat-generation device 7 is compressed again through screws.
Example (b):
the method is applied to carry out thermal design on certain satellite photoelectronic equipment, and the equipment mainly comprises a power supply module, an EDFA (erbium-doped fiber amplifier) module, an LD (laser diode) module, a data processing board, an optical signal transceiving control board, a high-power FPGA (field programmable gate array) device and the like. The thermal design is embodied as follows:
(1) thermal design of chassis
The case shell structure material is aluminum alloy material (6063 aluminum alloy plate), adopts six box structural design, and quick-witted case mounting plate thickness is 3.5mm, and other 5 panel thickness are 2.5 mm. Except the top cover plate, 4 other side panels and the bottom plate are milled into an integral structure, so that the heat transfer resistance between the side panels and the bottom plate is reduced, the mounting surfaces on the inner side and the outer side of the bottom plate are all full-contact surfaces, weight reduction grooves are avoided, and the flatness error of the mounting surface is required to be less than 0.1mm within the range of any 100mm multiplied by 100 mm. The lapping width of the top cover plate and each side panel connected with the top cover plate is 10mm, and the top cover plate and each side panel are connected and installed through screws. And heat conducting grease is coated between all the mutually connected panel contact surfaces of the casing structure of the machine case so as to reduce the contact heat resistance.
The outer surface of the case is anodized in black or sprayed with black paint (the surface emissivity is more than or equal to 0.85), so that the radiation heat dissipation is enhanced.
(2) Modular thermal design
The power module, the EDFA module and other modules are directly installed on the inner surface of the bottom panel of the chassis through screws, and heat conducting grease is coated between installation contact surfaces of all the modules so as to reduce contact thermal resistance. Black anodization or black paint spraying (the surface emissivity is more than or equal to 0.85) is carried out on the outer surface (except the installation surface) of the module, so that the radiation heat dissipation is enhanced.
The LD (laser) module has the requirement of precise control (35 +/-1 ℃) on the temperature, the TEC (thermoelectric refrigerator) is adopted to control the temperature, the hot surface of the LD module is arranged on the upper surface (cold surface) of the TEC, the lower surface (heat dissipation surface) of the TEC is directly arranged on the inner surface of the bottom panel of the case through screws, the LD module is compressed and fixed on the upper surface of the TEC through a red copper clamp, the two ends of the red copper clamp are fixed on the bottom panel of the case through screws, and heat conduction grease is coated between all installation contact surfaces to reduce the contact thermal resistance.
(3) PCB thermal design
The thickness of the PCB (data processing board, optical signal receiving and transmitting control board) is about 2mm, and the board is epoxy glass cloth. In order to improve the heat conduction path between the PCB and the casing of the chassis and provide a good heat dissipation channel for components, the following measures are taken when the circuit board is designed:
1) on the premise of meeting the electrical performance design, 8 copper layers with different thicknesses are coated in the PCB board, and the details are shown in Table 1.
TABLE 1 copper-clad layer in PCB
| Number of layers | Copper layer thickness (mum) | Copper-clad area percentage (%) | Remarks for note |
| 1 | 70 | 79.56 | |
| 2 | 35 | 94.28 | |
| 3 | 35 | 83.16 | |
| 4 | 35 | 90 | |
| 5 | 35 | 90 | |
| 6 | 35 | 90 | |
| 7 | 35 | 90 | |
| 8 | 70 | 91.48 |
2) The inner copper-clad layer extends to the edge of the circuit board mounting frame, and copper is clad on the outer surface of the circuit board mounting frame.
3) The local copper-clad area or the thickness of a copper-clad layer in a high-heating component (not less than 0.3W) mounting area is increased, the copper-clad layer extends to a circuit board mounting frame, and the high-heating component is an FPGA chip in the embodiment.
4) The width of the contact surface of the PCB mounting frame and the chassis structure mounting boss is 10mm, the PCB mounting frame and the chassis structure mounting boss are fixedly mounted through screws, and the mounting contact surface is coated with heat conduction grease.
The equivalent thermal conductivity of the PCB was calculated to be about 52.5W/(m · k) according to equation (1).
(4) Component thermal design
When the components are arranged and designed on the PCB, the high-power and high-heat-productivity components (FPGA chips) are arranged on the edge of the frame of the PCB on the premise of circuit design permission, and a heat transfer path between the FPGA chips and the case shell is shortened. The components should be distributed uniformly as much as possible, and especially the components with high power and large heat productivity avoid the concentration of heat sources. When the components are installed on the PCB, the length of the installation pins is as short as possible, and heat-conducting silicon rubber is coated between the installation surface of the heating components and the PCB to reduce heat transfer resistance.
Aiming at high-heating components randomly distributed on a PCB, a radiating panel is designed to serve as a heat collecting and transmitting reinforcing device, and the remote heat dissipation of point heat sources randomly distributed in space is realized. Adopt the components and parts heating surface design a cooling panel structure on the PCB board, cooling panel adopts low proportion, high thermal conductivity aluminum alloy (6063 aluminum alloy plate) material processing to form, and cooling panel structure and chassis shell structure carry out mechanical connection through the screw, and it is 10mm to connect the contact surface width, fills heat conduction fat between the contact surface.
According to the spatial geometric distribution position of the high-heating components on the PCB, structural boss shaping design is carried out on the corresponding projection position on the radiating panel, the geometric center of the structural boss coincides with the geometric center of the high-heating components connected with the structural boss, the outline of the boss is expanded by 5mm beyond the outline of the heating surface of the components, and the height of the boss is matched with the height of the high-heating components connected with the boss.
Considering the processing and assembly, a gap of 0.2 mm-0.3 mm is left, when in assembly, a Sil-Pad 2000 series heat-conducting elastic Pad with the thickness less than 0.3mm (after compression) is arranged between the structural lug boss and the contact surface of the component, and the elastic compression of the heat-conducting elastic Pad ensures the close contact of the three, thereby reducing the thermal contact resistance. In order to ensure that the structure boss, the heat conduction elastic pad and the component are in tight and stable contact, 2 screw installation interfaces are uniformly distributed on the PCB around the component and the corresponding heat dissipation panel, and the close contact among the structure boss, the heat conduction elastic pad and the heating surface of the component is compressed again through screws, so that the heat transfer resistance is reduced.
After the thermal design and implementation are completed, a device space flight working environment (cold black, vacuum and thermal environment) and a working mode are simulated in the space environment simulator, a thermal test verification is carried out on the heat dissipation method, and the verification result shows that: all modules meet the working temperature range, and the temperature of an LD (laser diode) module is controlled within 35 +/-1 ℃; all components meet the requirement of first-level derating of temperature, and the allowance is more than 20%, wherein the temperature of the high-heating FPGA (heat dissipation 10W) is about 15 ℃ of allowance away from the first-level derating temperature, and the heat dissipation effect of the heat dissipation panel structure is good.
Those skilled in the art will appreciate that the details of the invention not described in detail in the specification are within the skill of those skilled in the art.
Claims (12)
1. A heat dissipation method of space high heat consumption photoelectric equipment is characterized by comprising the following steps:
(1) the case is used as a main path for heat dissipation of the equipment function module, the PCB and the components, and optimized heat dissipation design of the case is carried out;
(2) dividing the functional modules packaged into an integrated structure into a common functional module and a functional module with a precise temperature control requirement, and performing optimized heat dissipation design on the functional modules packaged into an integrated structure in the case;
(3) calculating the equivalent thermal conductivity of the PCB, performing the optimized heat dissipation design of the PCB installed in the computer case, strengthening the conduction heat dissipation path between the PCB and the case shell, and optimizing the layout of high-heat-generation components;
(4) and the heat dissipation of the high-heating element on the PCB is enhanced, so that the heat dissipation effect of the high-heating element is improved.
2. The heat dissipation method for the space high heat consumption photoelectric device according to claim 1, wherein: carry out the optimization heat dissipation design of quick-witted case, specifically do: the casing structure of the case comprises a bottom plate, side plates and a cover plate which are all made of aluminum alloy materials, the bottom plate and the side plates are connected together and milled into an integral structure, the thermal resistance of a heat transfer path is reduced, and the cover plate is fixed on the upper sides of the side plates and used for sealing the case; the mounting surfaces of the inner side and the outer side of the chassis bottom plate are full contact surfaces without weight reduction grooves, and the surface of the chassis is subjected to high-emissivity surface treatment to strengthen space radiation heat dissipation.
3. The heat dissipation method for the space high heat consumption photoelectric device according to claim 2, wherein: the surface treatment with high emissivity on the surface of the case refers to spraying black paint or black anodizing; the wall thickness of the case is not less than 2.5mm, and the flatness error of the installation surface is required to be less than 0.1mm within the range of any 100mm multiplied by 100 mm.
4. The heat dissipation method for the space high heat consumption photoelectric device according to claim 1, wherein: carry out the interior optimization heat dissipation design who encapsulates functional module as an organic whole structure of quick-witted case, specifically do:
and for the common functional module, the common functional module is directly arranged and installed on the installation surface at the inner side of the chassis base plate, heat conducting filler is filled between the common functional module and the installation surface at the inner side of the chassis base plate to strengthen contact heat transfer, and the common functional module directly radiates heat through the chassis.
5. The heat dissipation method for the space high heat consumption photoelectric device according to claim 4, wherein: for the functional module with the requirement of precise temperature control, a thermoelectric refrigerator is firstly installed on the installation surface on the inner side of the chassis base plate, then the functional module with the requirement of precise temperature control is fixed on the thermoelectric refrigerator, and the thermoelectric refrigerator is used for carrying out bidirectional heat flow control of heating or refrigerating on the functional module with the requirement of precise temperature control, so that precise control of a temperature interval is realized; the functional module with the requirement of precise temperature control is fixedly arranged on the thermoelectric refrigerator through screws or metal hoops, the thermoelectric refrigerator is arranged on the mounting surface on the inner side of the bottom plate of the machine box through the screws, all contact surfaces are ensured to be in close contact, and heat conducting fillers are filled among all the mounting surfaces to strengthen contact heat transfer.
6. The heat dissipation method for the space high heat consumption photoelectric device according to claim 5, wherein: the common functional module is a functional module with the lowest working temperature lower than 0 ℃ and the highest working temperature higher than 50 ℃, the functional module with the requirement of precise temperature control is a laser module, and the working temperature range is 35 +/-1 ℃.
7. The heat dissipation method for the space high heat consumption photoelectric device according to claim 1, wherein: the optimized heat dissipation design of the PCB installed in the engine box specifically comprises the following steps:
the number of copper-clad layers of the PCB and the thickness of the copper-clad layer are increased, the equivalent thermal conductivity of the PCB is improved, the copper-clad layer extends to the edge of the circuit board mounting frame, and copper is clad on the outer surface of the circuit board mounting frame; increasing the local copper-clad area and the thickness of a copper-clad layer in a high-heating component mounting area; the high-heating element is an element with heat consumption more than or equal to 0.3W;
the heat conduction between the components and the PCB is realized through the contact of pins of the components, the contact surface between the components and the PCB is filled with heat conduction fillers, the width of the contact surface between the installation frame of the PCB and the casing of the case is not less than 5mm, the heat conduction fillers are filled between the contact surfaces, and the heat conduction fillers are installed and fixed by screws, so that the heat conduction and dissipation path between the PCB and the casing of the case is strengthened;
when the components are arranged, the high-heat-generating components are arranged at the edge of the PCB, so that a heat transfer path between the high-heat-generating components and the case shell is shortened; meanwhile, the high-heating components are distributed, so that the heat source concentration is avoided.
8. The method for dissipating heat from a photovoltaic device with high heat dissipation efficiency as claimed in claim 7, wherein: the equivalent thermal conductivity of the PCB board is calculated as follows:
in the formula, λEquivalent weightIs the equivalent thermal conductivity, lambda, of the PCBCuIs the thermal conductivity, lambda, of copper in the copper-clad layerPCBFor thermal conductivity of PCB plate material, HCu,iThe thickness of the ith copper-clad layer of the PCB is HPCB,iThe thickness of an ith plate interlayer of the PCB is set; pCu,iThe copper-clad area percentage of the ith copper-clad layer of the PCB is shown; n is the total number of copper layers coated on the PCB; and m is the total number of layers of the PCB plate interlayer.
9. The heat dissipation method for the space high heat consumption photoelectric device according to claim 1, wherein: carry out the heat dissipation of high heating element spare on the PCB board and strengthen the design, specifically do:
the high-heating components on the PCB are reinforced and radiated by the radiating panel, the radiating panel is mechanically connected with the case shell by screws, and heat-conducting fillers are filled between contact surfaces; according to the spatial geometric distribution position of the high-heating element on the PCB, a structural boss is arranged on the heat dissipation panel corresponding to the projection position, namely, the structural boss with the adaptive height corresponding to the geometric position of the high-heating element is arranged on the heat dissipation panel, so that the structural boss is in surface contact with the heating surface of the element; a heat-conducting elastic pad is arranged between the structural boss and the contact surface of the device, and the heat-conducting elastic pad is elastically compressed to ensure that the structural boss, the device and the device are in close contact, so that the thermal contact resistance is reduced; the PCB board around the high heating device and the heat dissipation panel are uniformly provided with a proper number of screw installation interfaces, and the heat dissipation panel structure boss, the heat conduction elastic pad and the device heating surface are pressed tightly again through screws.
10. The method for dissipating heat from a photovoltaic device with high heat dissipation efficiency as claimed in claim 9, wherein: the heat dissipation panel is formed by processing an aluminum alloy 6063 material, the width of a connecting contact surface between the heat dissipation panel and the case shell is not less than 5mm, and the thickness of the compressed heat conduction elastic pad is less than 0.3 mm.
11. A heat dissipation structure of a space high heat consumption photovoltaic device, which is realized by the heat dissipation method of the space high heat consumption photovoltaic device according to claim 1, characterized by comprising: the thermoelectric refrigerator comprises a case shell (1), a common function module (2), a thermoelectric refrigerator (3), a precise temperature control module (4), a PCB (printed circuit board) board (5), common components (6), high-heat-generation components (7), a heat-conducting elastic pad (8) and a heat-radiating panel (9);
the case shell (1) comprises a bottom plate, a side plate and a cover plate which are all made of aluminum alloy materials, the bottom plate and the side plate are connected together and milled into an integral structure, the thermal resistance of a heat transfer path is reduced, and the cover plate is fixed on the upper side of the side plate and used for sealing the case; mounting surfaces on the inner side and the outer side of the chassis bottom plate are full contact surfaces without weight reduction grooves, and the surface of the chassis is subjected to high-emissivity surface treatment to strengthen space radiation heat dissipation;
the common functional module (2) is directly arranged on the mounting surface on the inner side of the chassis base plate, heat dissipation is directly carried out through the chassis, and heat conducting fillers are filled between the common functional module and the mounting surface on the inner side of the chassis to strengthen contact heat transfer;
the thermoelectric refrigerator (3) is fixedly arranged on the mounting surface on the inner side of the bottom plate of the machine box, the precise temperature control module (4) is arranged on the thermoelectric refrigerator (3), and the thermoelectric refrigerator (3) is used for carrying out bidirectional heat flow control on heating or refrigerating of the precise temperature control module (4) so as to realize precise control of a temperature interval; the precise temperature control module (4) is fixedly arranged on the thermoelectric refrigerator (3) through screws or metal hoops, the thermoelectric refrigerator (3) is arranged on the mounting surface on the inner side of the bottom plate of the machine box through screws, all contact surfaces are ensured to be in close contact, and heat conducting fillers are filled between the mounting surfaces to strengthen contact heat transfer;
the PCB (5) is arranged in the case shell (1), a copper-clad layer of the PCB (5) extends to the edge of a circuit board mounting frame, copper is coated on the outer surface of the circuit board mounting frame, and a region where a high-heating component is arranged on the PCB (5) is subjected to treatment of locally increasing the copper-clad area and increasing the thickness of the copper-clad layer;
the common component (6) and the high-heating component (7) are both arranged on the PCB (5) and are in contact heat transfer with the PCB (5) through component pins, heat-conducting filler is filled in the contact surface between the components and the PCB, the width of the contact surface between the installation frame of the PCB (5) and the installation shell of the case is not less than 5mm, the heat-conducting filler is filled between the contact surfaces, and the components and the high-heating component are installed and fixed by screws;
the high-heat-generation component (7) is arranged at the edge of the PCB (5), and a heat transfer path between the high-heat-generation component (7) and the case shell (1) is shortened; meanwhile, the high-heating components (7) are distributed, so that the heat source concentration is avoided;
the high-heating component (7) on the PCB is reinforced and radiated through the radiating panel (9), the radiating panel (9) and the case shell (1) are mechanically connected through screws, and heat-conducting fillers are filled between contact surfaces; according to the space geometric distribution position of the high-heating element (7) on the PCB, a structure boss is arranged on the heat dissipation panel (9) corresponding to the projection position, so that the structure boss is in surface contact with the heating surface of the high-heating element (7); a heat-conducting elastic pad (8) is arranged between the contact surface of the structural boss and the high-heating component (7), and the heat-conducting elastic pad (8) is elastically compressed to ensure that the three are in close contact with each other, so that the thermal contact resistance is reduced; screw installation interfaces are uniformly distributed on the PCB (5) and the heat dissipation panel (9) around the high-heat-generation device (7), and the structural boss of the heat dissipation panel (9), the heat conduction elastic pad (8) and the heat generation surface of the high-heat-generation device (7) are pressed again through screws to contact with each other.
12. The heat dissipation structure of a space high heat consumption optoelectronic device according to claim 11, wherein: the surface treatment with high emissivity on the surface of the case refers to spraying black paint or black anodizing; the wall thickness of the case is not less than 2.5mm, and the flatness error of the installation surface is required to be less than 0.1mm within the range of any 100mm multiplied by 100 mm; the high-heating element is an element with heat consumption more than or equal to 0.3W;
the common functional module (2) is a functional module with the lowest working temperature lower than 0 ℃ and the highest working temperature higher than 50 ℃, the precise temperature control module (4) is a laser module, and the working temperature range of the precise temperature control module is 35 +/-1 ℃;
the heat dissipation panel is formed by processing an aluminum alloy 6063 material, the width of a connecting contact surface between the heat dissipation panel and the case shell is not less than 5mm, and the thickness of the compressed heat conduction elastic pad is less than 0.3 mm.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112882510A (en) * | 2021-01-19 | 2021-06-01 | 西安应用光学研究所 | Onboard photoelectric turret global thermal control device |
| CN113423246A (en) * | 2021-06-29 | 2021-09-21 | 长光卫星技术有限公司 | Light device for efficient heat dissipation of cubic satellite electronic equipment |
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2020
- 2020-07-31 CN CN202010760659.2A patent/CN111902024A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112882510A (en) * | 2021-01-19 | 2021-06-01 | 西安应用光学研究所 | Onboard photoelectric turret global thermal control device |
| CN112882510B (en) * | 2021-01-19 | 2022-02-15 | 西安应用光学研究所 | Onboard photoelectric turret global thermal control device |
| CN113423246A (en) * | 2021-06-29 | 2021-09-21 | 长光卫星技术有限公司 | Light device for efficient heat dissipation of cubic satellite electronic equipment |
| CN113423246B (en) * | 2021-06-29 | 2023-01-10 | 长光卫星技术股份有限公司 | Light device for efficient heat dissipation of cubic satellite electronic equipment |
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