Method for preparing water-cooled copper-based PCB

Abstract

The invention belongs to the technical field of electronic manufacturing, and relates to a method for preparing a water-cooled copper-based PCB (printed circuit board), which comprises the following steps of: respectively processing micro-channel grooves on two copper substrates, and welding the two copper substrates together to enable the micro-channel grooves of the two copper substrates to be in central mirror symmetry; processing a through hole in the copper substrate, and filling the through hole with resin; placing PCB core boards on the front surface and the back surface of the copper substrate respectively to obtain a PCB; and secondary drilling is carried out on the PCB, and electroplating is carried out on a through hole of the secondary drilling to obtain the water-cooling copper-based PCB. The water-cooling copper-based PCB prepared by the method can rapidly export heat, is suitable for a high-power and high-integration TR module, and has the advantages of being light, thin and rapid in heat conduction.

Description

Technical Field

[0001] The invention relates to the technical field of electronic manufacturing, and in particular to a method for preparing a water-cooled copper-based PCB board. Background Art

[0002] In order to achieve good heat dissipation of PCB, metallized through holes are usually drilled on the PCB board, and the heat generated by the components on the board is conducted to the heat dissipation structure through the metallized through holes. This method has high thermal resistance and poor thermal conductivity, which can easily cause heat accumulation of components on the board, resulting in the components not being able to work properly. On the other hand, in the field of TR applications, which are becoming more and more integrated, the heat density of TR modules is high. To achieve high integration, TR chips can only be soldered on the board. Soldering on the PCB has poor heat dissipation effect due to the large thermal resistance of the metallized holes. If the chip is soldered on a structural part, the longitudinal thickness of the TR module will increase, and the volume size will increase.

[0003] In view of this, this application is hereby filed. Summary of the invention

[0004] The technical problem to be solved by the present invention is that the existing TR module cannot achieve high integration and high heat dissipation performance at the same time.

[0005] In order to solve the above technical problems, the present invention is implemented by the following technical solutions:

[0006] A method for preparing a water-cooled copper-based PCB board is proposed, comprising the following steps: machining a first microchannel groove on a first copper substrate, and machining a second microchannel groove on a second copper substrate; setting a first interface at the end of the first microchannel groove, and setting a second interface at the end of the second microchannel groove; the first interface and the second interface are both connected to an external liquid cooling system; pressing and welding the first copper substrate having the first microchannel groove and the first interface with the second copper substrate having the second microchannel groove and the second interface together to obtain a third copper substrate; in the third copper substrate, the first microchannel groove and the second microchannel groove are centrally mirror-symmetrical; machining a first through hole on the third copper substrate, filling the first through hole with resin, and obtaining a fourth copper substrate with a resin hole; placing a first PCB core board on the front side of the fourth copper substrate, and placing a second PCB core board on the back side of the fourth copper substrate, to obtain a PCB board; machining a second through hole at a position corresponding to the resin hole on the PCB board, electroplating the second through hole, and obtaining the water-cooled copper-based PCB board; the second through hole runs through the first PCB core board, the resin hole, and the second PCB core board.

[0007] Furthermore, the method for preparing a water-cooled copper-based PCB board also includes the following steps: processing a blind groove on the first PCB core board; the depth of the blind groove is equal to the depth of the first PCB core board.

[0008] Furthermore, the processing technology of the blind groove is: controlled depth milling technology.

[0009] Furthermore, the thickness of the first copper substrate and the thickness of the second copper substrate are both 0.5 mm; the depth of the first microfluidic groove and the depth of the second microfluidic groove are both 0.2 mm, and the width of the first microfluidic groove and the width of the second microfluidic groove are both 0.1 mm to 0.5 mm.

[0010] Furthermore, the processing technology of the first microfluidic groove and the processing technology of the second microfluidic groove are both controlled depth milling processes.

[0011] Furthermore, the method of filling the first through hole with resin is: continuously filling the first through hole with epoxy resin or polyimide resin until the epoxy resin or the polyimide resin overflows the first through hole; the height of the overflowed epoxy resin or the height of the overflowed polyimide resin is 0.1 mm.

[0012] Furthermore, after the first through hole is filled with resin, the method further includes the following steps: using a depth-controlled grinding wheel to grind the overflowed epoxy resin or overflowed polyimide resin to make it smooth.

[0013] Furthermore, after obtaining the fourth copper substrate having resin holes, the method further includes the following steps: preheating the fourth copper substrate to 100°C.

[0014] Furthermore, the method for placing the first PCB core board on the front side of the fourth copper substrate is: pressing the first PCB core board on the front side of the fourth copper substrate at a temperature of 500°C; the method for placing the second PCB core board on the back side of the fourth copper substrate is: pressing the second PCB core board on the back side of the fourth copper substrate at a temperature of 500°C.

[0015] Furthermore, the electroplating includes: chemical copper plating or electrolytic copper plating.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: a microchannel groove is processed on a copper substrate by a controlled depth milling process, and two copper substrates are pressed and welded together in a mirror-symmetrical manner by welding technology to form a copper substrate with a microchannel groove. Subsequently, a copper-based PCB with a water-cooled microchannel is prepared by controlled depth milling, resin filling, PCB pressing, drilling, electroplating and other steps. The water-cooled copper-based PCB can quickly conduct heat, is suitable for high-power and highly integrated TR modules, and has the advantages of being light, thin and fast in heat conduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A flow chart of a method for preparing a water-cooled copper-based PCB board provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0020] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to one of ordinary skill in the art that these specific details are not necessarily employed to practice the present invention. In other embodiments, in order to avoid obscuring the present invention, well-known structures, circuits, materials, or methods are not specifically described.

[0021] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. In addition, it will be appreciated by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] In the description of the present invention, the directions or positional relationships indicated by terms such as “front”, “rear”, “left”, “right”, “up”, “down”, “vertical”, “horizontal”, “high”, “low”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the scope of protection of the present invention.

[0023] Embodiment: A method for preparing a water-cooled copper-based PCB board is proposed, comprising: Figure 1 The following steps are shown:

[0024] Step 1: Select two copper substrates of the same size and mark them as the first copper substrate and the second copper substrate respectively.

[0025] The thickness of the first copper substrate and the second copper substrate are both 0.5 mm.

[0026] Step 2: Processing a first microchannel groove on the first copper substrate and processing a second microchannel groove on the second copper substrate.

[0027] The processing technology of the first microchannel groove and the processing technology of the second microchannel groove are both controlled depth milling processes, the depth of the first microchannel groove and the depth of the second microchannel groove are both 0.2mm, and the width of the first microchannel groove and the width of the second microchannel groove are both 0.1mm to 0.5mm. In addition, the first microchannel groove and the second microchannel groove are located inside the copper substrate and are mirror-symmetrical in the center, forming a closed liquid cooling channel.

[0028] Step 3: A first interface is provided at the end of the first microfluidic channel, and a second interface is provided at the end of the second microfluidic channel.

[0029] The first interface and the second interface are both connected to an external liquid cooling system. Liquid cooling liquid enters the water cooling microchannel inside the copper substrate through the interface to quickly remove heat from the copper substrate.

[0030] Step 4: Press and weld the first copper substrate and the second copper substrate obtained in step 3 together to obtain a third copper substrate.

[0031] The first copper substrate and the second copper substrate are welded together by welding technology in a mirror-symmetrical manner to form a 1mm thick copper substrate with a microchannel groove. The welding layer is located between the two copper substrates to ensure the sealing of the microchannel groove. The welding technology used is vacuum welding or hot pressing welding.

[0032] Step 5: Process a first through hole on the third copper substrate, and fill the first through hole with resin to obtain a fourth copper substrate with resin holes.

[0033] A first through hole with a depth of 1 mm is machined on the third copper substrate formed in step 4 using a depth-controlled milling cutter, and the diameter of the first hole is determined according to the PCB design aperture size. The first through hole is continuously filled with epoxy resin or polyimide resin until the epoxy resin or the polyimide resin overflows the first through hole, and the height of the overflowed epoxy resin or the overflowed polyimide resin is 0.1 mm.

[0034] Step 6: Sand any spilled resin smooth.

[0035] Use a controlled depth grinding wheel to grind the overflowed epoxy resin or overflowed polyimide resin flat to prepare for subsequent PCB drilling.

[0036] Step 7: preheat the fourth copper substrate, then place the first PCB core board on the front side of the fourth copper substrate, and place the second PCB core board on the back side of the fourth copper substrate to obtain a PCB board.

[0037] Specifically, the fourth copper substrate is preheated to 100° C., and the first PCB core is placed on the front of the fourth copper substrate, and the second PCB core is placed on the back of the fourth copper substrate, and the first PCB core and the second PCB core are tightly pressed on the front and back of the fourth copper substrate at a temperature of 500° C. Circuits are prefabricated on the first PCB core and the second PCB core.

[0038] Step 8: Process a second through hole at a position corresponding to the resin hole on the PCB board, and electroplate the second through hole.

[0039] The thick PCB board pressed in step 7 is drilled a second time, starting from the front side of the PCB, through the copper-based resin hole, and then to the back side of the PCB to form a second through hole. The second through hole is electroplated (chemical copper plating or electroplating copper) to metalize the front side PCB, the resin hole and the back side PCB, thereby electrically connecting the front and back sides of the PCB.

[0040] Step 9: Process a blind groove on the first PCB core board to obtain a water-cooled copper-based PCB board.

[0041] Use controlled depth milling to perform blind groove controlled depth milling on the PCB board obtained in step 8, and control the milling depth to the upper surface of the front copper base to complete the blind groove production, which is used to further optimize the heat dissipation performance of the PCB.

[0042] In summary, the method for preparing a water-cooled copper-based PCB board proposed in this embodiment is suitable for preparing a high-power, highly integrated TR module, can achieve rapid heat exchange, ensure module performance, and reduce the thickness of the TR module to achieve lightness and thinness.

[0043] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a water-cooled copper-based PCB board, characterized in that: The following steps are involved: A first microchannel groove is processed on the first copper substrate, and a second microchannel groove is processed on the second copper substrate; A first interface is provided at the end of the first microchannel groove, and a second interface is provided at the end of the second microchannel groove; the first interface and the second interface are both connected to an external liquid cooling system; The first copper substrate having the first microfluidic groove and the first interface and the second copper substrate having the second microfluidic groove and the second interface are pressed and welded together to obtain a third copper substrate; in the third copper substrate, the first microfluidic groove and the second microfluidic groove are centrally mirror-symmetrical; Processing a first through hole on the third copper substrate, and filling the first through hole with resin to obtain a fourth copper substrate having a resin hole; Placing a first PCB core board on the front side of the fourth copper substrate, and placing a second PCB core board on the back side of the fourth copper substrate, to obtain a PCB board; A second through hole is processed at a position corresponding to the resin hole on the PCB board, and the second through hole is electroplated to obtain the water-cooled copper-based PCB board; the second through hole passes through the first PCB core board, the resin hole and the second PCB core board.

2. A method for preparing a water-cooled copper-based PCB board according to claim 1, characterized in that: The following steps are also included: A blind groove is processed on the first PCB core board; the depth of the blind groove is equal to the depth of the first PCB core board.

3. A method for preparing a water-cooled copper-based PCB board according to claim 2, characterized in that: The processing technology of the blind groove is: controlled depth milling technology.

4. A method for preparing a water-cooled copper-based PCB board according to any one of claims 1 to 3, characterized in that: The thickness of the first copper substrate and the thickness of the second copper substrate are both 0.5 mm; The depth of the first microfluidic channel groove and the depth of the second microfluidic channel groove are both 0.2 mm, and the width of the first microfluidic channel groove and the width of the second microfluidic channel groove are both 0.1 mm to 0.5 mm.

5. A method for preparing a water-cooled copper-based PCB board according to any one of claims 1 to 3, characterized in that: The processing technology of the first microfluidic channel groove and the processing technology of the second microfluidic channel groove are both controlled depth milling processes.

6. A method for preparing a water-cooled copper-based PCB board according to any one of claims 1 to 3, characterized in that: The method of filling the first through hole with resin is: continuously filling the first through hole with epoxy resin or polyimide resin until the epoxy resin or the polyimide resin overflows the first through hole; the height of the overflowed epoxy resin or the overflowed polyimide resin is 0.1 mm.

7. A method for preparing a water-cooled copper-based PCB board according to claim 6, characterized in that: After the first through hole is filled with resin, the method further includes the following steps: grinding the overflowed epoxy resin or overflowed polyimide resin flat with a depth-controlled grinding wheel.

8. A method for preparing a water-cooled copper-based PCB board according to any one of claims 1 to 3, characterized in that: After obtaining the fourth copper substrate with resin holes, the method further includes the following steps: preheating the fourth copper substrate to 100°C.

9. A method for preparing a water-cooled copper-based PCB board according to any one of claims 1 to 3, characterized in that: The method of placing the first PCB core board on the front surface of the fourth copper substrate is: pressing the first PCB core board on the front surface of the fourth copper substrate at a temperature of 500° C.; The method for placing the second PCB core board on the back side of the fourth copper substrate is: pressing the second PCB core board on the back side of the fourth copper substrate at a temperature of 500°C.

10. A method for preparing a water-cooled copper-based PCB board according to any one of claims 1 to 3, characterized in that: The electroplating includes: chemical copper plating or electro copper plating.

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