Air-cooled cold plate and manufacturing method thereof

Abstract

An air-cooled cold plate is I-shaped, the side face of one end of the cold plate is a fan mounting face, the bottom face of the other end of the cold plate is a base mounting face, the side face of the middle section of the cold plate is a printed board mounting face, the cross section of the middle section of the cold plate is a crystal oscillator mounting face, fins are arranged in the middle section, air channels are formed among the fins, and a plurality of ventilation openings are formed in the fan mounting face and the base mounting face. The ventilation openings are communicated through fin air ducts; the manufacturing method comprises the steps that selective laser melting is adopted for a blank, 3D printing is adopted for a cold plate blank, a plugging tool is manufactured according to the appearance of an air duct opening, 3D printing is adopted for cold plate rough machining, stress relief annealing is conducted, heat treatment is adopted for releasing machining stress, an ultrasonic thickness gauge is adopted for measuring the thickness of a printed plate mounting face, the thickness allowance is set, and the finish machining allowance is determined. And the machining benchmark is offset, feature finish machining is conducted on the fan installation face, the printed board installation face, the base installation face and the crystal oscillator installation face, and deionized water is adopted to repeatedly wash the air channel.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mechanical processing, and particularly relates to a 3D printing hollow structure technology. BACKGROUND

[0002] The air-cooled cold plate is an important carrier of electronic components such as radio frequency modules, high-voltage power supplies and TR components of complex electronic equipment such as radars. The air-cooled cold plate is usually made of aluminum alloy sheet, and is completed through processes such as machining, welding, machining and surface treatment. The platforms of aviation and aerospace equipment are further developed in the direction of high power, high integration and light weight, and the height, thickness and spacing of the fins of the air-cooled cold plate are further extreme, and the traditional vacuum brazing, diffusion welding and friction stir welding processes cannot meet the current needs. As a new technology, 3D printing, in combination with subsequent precision machining, provides more possibilities for the design of air-cooled cold plates.

[0003] How to control the forming precision of the air-cooled cold plate in additive and subtractive manufacturing is a great challenge, and breaking through the related technical difficulties can greatly expand the application of additive and subtractive combined manufacturing technology in complex electronic equipment. Patent CN100491058C discloses a sealing process for an aluminum alloy air-cooled cold plate, which uses machining to prepare the cold plate shell, fins and cover plate. The heat dissipation fins are welded to the cold plate shell and cover plate by nitrogen protection welding, and the vertical weld between the cover plate and the shell is welded by friction stir welding, and the shape is finished. The fins processed by this method are thicker and shorter, which cannot meet the current heat dissipation needs of electronic equipment. SUMMARY

[0004] In order to solve the technical problems of the high, thick, large spacing, easy to irregularly dump, increase wind resistance and affect heat dissipation of the fins in the traditional process, the structure of the air-cooled cold plate in the form of I-shaped is adopted.

[0005] The side surface of one end is a fan mounting surface, the bottom surface of the other end is a base mounting surface, the side surface of the middle section is a printed board mounting surface, the cross section of the middle section is a crystal vibration mounting surface, the fins are arranged in the middle section, the air duct is formed between the fins, and a plurality of ventilation openings are formed in the fan mounting surface and the base mounting surface, and the ventilation openings are communicated through the fin air duct.

[0006] The processing process is as follows: Step one: using laser selective melting blank, using 3D printing cold plate blank, using heat treatment to adjust the strength of the cold plate, using wire cutting to remove the support, and polishing the surface of the blank.

[0007] Step two: according to the shape of the air duct opening, making a plugging tool, and using 3D printing cold plate rough machining.

[0008] Step three: stress relief annealing, using heat treatment to release the processing stress.

[0009] Step four: measure the thickness of the printed board mounting surface 1.2 by using ultrasonic thickness gauge, set the thickness allowance, and determine the finishing allowance.

[0010] Step five: offset processing reference, feature finishing of fan mounting surface, printed board mounting surface, base mounting surface, and crystal mounting surface.

[0011] Step six: clean the air duct by repeatedly flushing it with deionized water, and clean the surface with hydrofluoric acid. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a cold plate structure diagram.

[0013] Figure 2 is a cold plate manufacturing flowchart.

[0014] Figure 3 is a rough 3D printing diagram. DETAILED DESCRIPTION

[0015] The technical solutions of the present application are described in detail below in combination with the drawings.

[0016] The structure of the air-cooled cold plate is shown in Figure 1 , which is an I-shaped structure, the side surface at one end is the fan mounting surface 1.1, the bottom surface at the other end is the base mounting surface 1.3, the side surface of the middle section is the printed board mounting surface 1.2, the cross section of the middle section is the crystal mounting surface 1.4, the middle section is provided with fins 1.5 inside, and the air duct is formed between the fins. The fan mounting surface 1.1 and the base mounting surface 1.3 are both provided with several ventilation openings, and the ventilation openings are connected by the fin air duct.

[0017] According to the heat dissipation requirement, the height and thickness of the fins, the distance between the fins in the same cluster, and the position of the fins in different clusters are designed by thermal simulation, and the connection between the fins and the fan mounting surface 1.1 is increased with a round corner, so that no collapse occurs during 3D printing.

[0018] The specific processing process is shown in Step one: use laser selective melting to process the rough, use 3D printing cold plate rough, as shown in Figure 3 , use heat treatment to adjust the strength of the cold plate, use wire cutting to remove the support, and polish the surface of the rough.

[0019] The thickness of the printed board mounting surface 1.2 is 1mm, the tolerance is ±0.1mm, and the flatness is 0.1mm. According to the height of the surface-mounted components, set the boss.

[0020] The thickness of the crystal mounting surface 1.4 is 0.8mm, and the cross beam and mounting hole are set according to the size of the surface-mounted crystal, without processing features.

[0021] According to the cold plate model, the crossbeam of the crystal oscillator mounting surface 1.4, the fan mounting surface 1.1, the printed board mounting surface 1.2, and the base mounting surface 1.3 are all increased by 2mm excess, and the other positions of the crystal oscillator mounting surface, the fins, and the spoiler column are not increased.

[0022] With the base mounting surface 1.3 as the reference, the cold plate is printed at an angle of 45°, and supports are added to the crystal oscillator mounting surface 1.4 to control the machining precision of the printed board mounting surface 1.2.

[0023] Using simulation calculation, it is determined that the cold plate deformation is concentrated in the middle section of the fan mounting surface 1.1 and the crystal oscillator mounting surface 1.4, and the support thickness is set to 4.5mm, and the support thickness of other positions is 3mm.

[0024] AlSi10Mg powder is used as the blank material, with a particle size of 15-35um and a powder layer thickness of 0.03mm.

[0025] The fins are formed by laser printing with a power of 200W, a scanning interval of 0.15mm, a scanning speed of 1000mm / s, and a heat treatment temperature not higher than 220℃ to ensure the forming precision.

[0026] Step two: According to the shape of the air duct opening, make a plugging tool, and use 3D printing cold plate rough machining.

[0027] The lower surface of the crystal oscillator mounting surface 1.4 is used as the reference surface to calculate the excess, the crystal oscillator mounting surface 1.4 is not machined, and the other machined surfaces are reserved with 1mm finishing allowance.

[0028] The feed speed of cold plate rough machining is 700mm / min, and the spindle speed is 5000r / min.

[0029] Step three: stress relief annealing, using heat treatment to release processing stress.

[0030] The temperature does not exceed the heat treatment temperature after 3D printing, which is 180-200℃, and the time is 12 hours.

[0031] Step four: Use ultrasonic thickness gauge to measure the thickness of the printed board mounting surface 1.2, set the thickness allowance, and determine the finishing allowance.

[0032] Step five: offset machining reference, feature finishing of fan mounting surface 1.1, printed board mounting surface 1.2, base mounting surface 1.3, and crystal oscillator mounting surface 1.4.

[0033] The feed speed of cold plate finishing is 800mm / min, and the spindle speed is 5500r / min.

[0034] Step six: Use deionized water to repeatedly flush the air duct to make it clean, and use hydrofluoric acid to clean the surface.

[0035] The above embodiments of the present application are not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application are included in the scope of the present application.

Claims

1. An air-cooled cold plate, characterized by, The cold plate is an I-shaped plate, one side of which is a fan mounting surface, the bottom of the other end is a base mounting surface, the side of the middle section is a printed board mounting surface, the cross section of the middle section is a crystal oscillator mounting surface, and fins are arranged inside the middle section, and air ducts are formed between the fins. The fan mounting surface and the base mounting surface are each provided with a plurality of ventilation openings, and the ventilation openings are connected by the fin air ducts. The thickness of the printed board mounting surface is 1 mm, the tolerance is ±0.1 mm, and the flatness is 0.1 mm. The boss is arranged according to the height of the surface-mounted component.

2. The air-cooled cold plate of claim 1, wherein, The thickness of the crystal oscillator mounting surface is 0.8 mm, and the crossbeam and mounting hole are arranged according to the size of the surface-mounted crystal oscillator, and no features are processed.

3. The air-cooled cold plate of claim 1, wherein, The cold plate is an I-shaped plate, one side of which is a fan mounting surface, the bottom of the other end is a base mounting surface, the side of the middle section is a printed board mounting surface, the cross section of the middle section is a crystal oscillator mounting surface, and fins are arranged inside the middle section, and air ducts are formed between the fins. The fan mounting surface and the base mounting surface are each provided with a plurality of ventilation openings, and the ventilation openings are connected by the fin air ducts.

4. A method of manufacturing an air-cooled cold plate according to claim 1, characterized by, The step one comprises: according to the cold plate model, 2mm excess is added to the crossbeam of the crystal oscillator mounting surface, the fan mounting surface, the printed board mounting surface and the base mounting surface, and no excess is added to other positions of the crystal oscillator mounting surface, the fins and the spoiler column. The cold plate is printed at an inclination of 45° based on the base mounting surface, and supports are added to the crystal oscillator mounting surface to control the machining precision of the printed board mounting surface. The simulation calculation is used to determine that the deformation of the cold plate is concentrated in the middle section of the fan mounting surface and the crystal oscillator mounting surface, the support thickness is set to be 4.5mm, and the support thickness of other positions is set to be 3mm. The step one comprises: AlSi10Mg powder is used as the blank material, the particle size is 15-35um, the powder layer thickness is 0.03mm, the fins are formed by laser printing with a power of 200W, the scanning interval is 0.15mm, the scanning speed is 1000mm / s, and the heat treatment temperature is not higher than 220℃. The step two comprises: the excess is calculated based on the lower surface of the crystal oscillator mounting surface, the crystal oscillator mounting surface is not machined, and 1mm machining excess is reserved for other machined surfaces; the feeding speed of the cold plate rough machining is 700mm / min, and the spindle speed is 5000r / min. The step three comprises: the heat treatment temperature is not higher than the heat treatment temperature after 3D printing, which is 180-200℃, and the time is 12 hours. The step five comprises: the feeding speed of the cold plate machining is 800mm / min, and the spindle speed is 5500r / min. ​ 5. The method of manufacturing an air-cooled cold plate of claim 4, wherein, ​ ​ ​ 6. The method of manufacturing an air-cooled cold plate of claim 4, wherein, ​ 7. The method of manufacturing an air-cooled cold plate of claim 4, wherein, ​ 8. The method of manufacturing an air-cooled cold plate of claim 4, wherein, ​ 9. The air-cooled cold plate of claim 4, wherein, ​

Images