Packaging substrate with microstructured cavities and method of manufacturing thereof

Abstract

The application relates to the technical field of packaging substrate manufacturing, in particular to a packaging substrate with a micro-structure cavity and a preparation method thereof. The preparation method of the packaging substrate with the micro-structure cavity comprises the following steps: providing a base material plate with a first metal layer; electroplating a second metal layer on the first metal layer, wherein the second metal layer comprises a plurality of column structures distributed at intervals and a frame structure surrounding the outer periphery of the column structures; a phase change medium injection port is formed on the frame structure; a metal cover plate is formed on the second metal layer, so that the metal cover plate, the frame structure and the first metal layer jointly form a cavity; phase change medium is injected into the cavity through the phase change medium injection port, and the cavity is closed. The preparation method of the packaging substrate with the micro-structure cavity can effectively reduce the thermal resistance of heat conduction from a power device to a heat dissipation device, so that a higher power density power device can be packaged in a unit volume.

Description

Technical Field

[0001] This application relates to the field of packaging substrate manufacturing technology, and more specifically, to a packaging substrate with microstructured chambers and a method for preparing the same. Background Technology

[0002] Packaging substrates provide electrical connections, protection, support, heat dissipation, and assembly for power devices such as chips, enabling multi-pin configurations, reduced package size, improved electrical performance and heat dissipation, ultra-high density, or modularization of multiple devices. To effectively dissipate heat from power devices, heat dissipation devices are often mounted on the packaging substrate, typically connected to the substrate via thermal interface material (TIM). With advancements in third-generation semiconductors, the power density of power device packages is increasing, placing higher demands on the composite thermal conductivity of the packaging substrate and lower expectations for thermal resistance.

[0003] To effectively reduce thermal resistance, a common approach is to create a packaging substrate by coating one or both sides with copper on a high thermal conductivity substrate. Increasing the copper area and thickness improves thermal conductivity and reduces thermal resistance. However, copper has limited thermal conductivity, resulting in poor thermal resistance reduction. Furthermore, cost and current technology limit the replacement of copper with other high thermal conductivity materials such as graphene, diamond, and carbon nanotubes. In addition, the connection between the heat dissipation device and the packaging substrate via a thermally conductive integrated membrane (TIM) often results in significant thermal resistance between the packaging substrate and the heat dissipation device, hindering effective heat dissipation for the power devices. Summary of the Invention

[0004] The purpose of this application is to provide a packaging substrate with a microstructured cavity and a method for fabricating the same, which aims to improve the technical problem of high thermal resistance in existing packaging substrates for conducting heat from power devices to heat dissipation devices.

[0005] In a first aspect, this application provides a method for fabricating a packaging substrate with a microstructured cavity, comprising:

[0006] Provide a substrate board having a first metal layer.

[0007] A second metal layer is formed by electroplating on the first metal layer; wherein the second metal layer includes a plurality of spaced columnar structures and a frame structure surrounding the plurality of columnar structures; a phase change medium injection port is provided on the frame structure.

[0008] A metal cover is formed on the second metal layer so that the metal cover, the frame structure, and the first metal layer together constitute the chamber.

[0009] The phase change medium is injected into the chamber through the phase change medium injection port, and the chamber is closed.

[0010] The application forms a chamber with a plurality of spaced column structures inside on a substrate plate in an electroplating additive manner, realizes integrally formed preparation of a packaging substrate with a micro-structured chamber (i.e. a heat dissipation device), and avoids the case that the thermal resistance between the substrate plate and the vacuum chamber heat spreader (VC) is large due to the setting of the TIM.

[0011] The plurality of column structures inside the chamber form a capillary structure, and the chamber contains a phase change medium, so that the integrally formed packaging substrate with a micro-structured chamber forms a structure with a heat pipe (HP) and a vacuum chamber heat spreader (VC) at the same time, so that heat can be quickly spread in the three directions of space xyz to realize fast heat conduction, thereby effectively reducing the thermal resistance of the packaging substrate to conduct the heat of the power device to the heat dissipation device, so that a higher power density power device can be packaged in a unit volume.

[0012] In addition, the electroplating additive manner can effectively form column structures with high specific surface area, can effectively control the thickness of the chamber to any thickness, and can effectively control the shape of the chamber and the shape of the column inside the chamber, so that the application range of the prepared packaging substrate is wider.

[0013] In some embodiments of the first aspect of the application, the substrate plate includes a ceramic material as a base, and the first metal layer is covered on the base.

[0014] The ceramic material has high thermal conductivity, good insulation performance, and stable physical and chemical properties; the ceramic material has a small thermal expansion coefficient, which is close to the thermal expansion coefficient of the chip power device; and the ceramic material has a certain rigidity, which is beneficial to avoid the phenomenon that the deformation of the substrate plate caused by the change of cold and hot temperature during electroplating affects the shape of the microstructure in the chamber, and thus is beneficial to the rapid diffusion of heat source to the entire substrate, thereby greatly reducing the thermal resistance.

[0015] In some embodiments of the first aspect of the application, the method of covering the first metal layer on the base includes: forming the first metal layer on the surface of the base in a sputtering or vapor deposition manner.

[0016] Since the base is made of insulating ceramic material, the sputtering or vapor deposition manner can form the first metal layer on the insulating base, and the connection between the base and the first metal layer is strong, thereby being beneficial to improving the structural stability of the integrally formed packaging substrate with a micro-structured chamber.

[0017] In some embodiments of the first aspect of the present application, the step of forming the second metal layer comprises: locally shielding the first metal layer with the insulating material to form a first patterned region of the first metal layer, and then electroplating the substrate to thicken the first metal layer in the first patterned region; wherein the first patterned region comprises a patterned region corresponding to the column structure and the frame structure.

[0018] The step of forming the metal cover plate is further followed by a step of removing the insulating material.

[0019] In this way, the second metal layer with the plurality of spaced column structures and the frame structure surrounding the plurality of column structures can be effectively formed by electroplating.

[0020] In some embodiments of the first aspect of the present application, the step of forming the second metal layer comprises: covering the first metal layer with a first exposure and development film, exposing and developing to form a first patterned region of the first metal layer; and then electroplating the substrate to thicken the first metal layer in the first patterned region.

[0021] The step of forming the metal cover plate is further followed by a step of removing the first exposure and development film inside and outside the cavity.

[0022] By using the exposure and development principle, the pattern to be plated can be effectively formed, and the second metal layer with the plurality of spaced column structures and the frame structure surrounding the plurality of column structures can be formed by electroplating.

[0023] In some embodiments of the first aspect of the present application, the step of forming the metal cover plate comprises: forming a third metal layer on the second metal layer by physical vapor deposition, covering the third metal layer with a second exposure and development film, exposing and developing to form a second patterned region of the third metal layer; etching the uncovered region of the third metal layer, and then removing the second exposure and development film.

[0024] In some embodiments of the first aspect of the present application, the step of forming the metal cover plate comprises: covering the third metal layer with a third exposure and development film, exposing and developing to form a third patterned region of the third metal layer; electroplating the third metal layer to thicken the third metal layer in the third patterned region, and then removing the third exposure and development film to obtain the metal cover plate; wherein the second patterned region and the third patterned region are both patterned regions corresponding to the edges of the frame structure.

[0025] In some embodiments of the first aspect of the present application, the step of forming the metal cover plate is further followed by a step of etching the first metal layer outside the frame structure region.

[0026] In some embodiments of the first aspect of the present application, the step of forming the metal cover plate comprises: welding the metal cover plate on the second metal layer.

[0027] In some embodiments of the first aspect of the present application, the method further comprises: etching the first metal layer outside the frame structure region between the step of forming the second metal layer and the step of forming the metal cover plate.

[0028] In some embodiments of the first aspect of the present application, the method of sealing the cavity comprises: pressure welding the surface of the metal cover plate away from the second metal layer so that the phase change medium injection port is not in communication with the cavity.

[0029] By pressure welding the surface of the metal cover plate away from the second metal layer so that the phase change medium injection port is not in communication with the cavity, a protruding filling structure is not formed, and the application range of the prepared packaging substrate is wider.

[0030] In some embodiments of the first aspect of the present application, the number of phase change medium injection ports opened on the frame structure is two, and the method of sealing the cavity comprises: using an external pump to communicate the two phase change medium injection ports so that the phase change medium in the cavity can flow circularly.

[0031] The above arrangement can make the phase change medium flow circularly in the cavity, which is beneficial to further improve the heat dissipation effect.

[0032] In some embodiments of the first aspect of the present application, the two surfaces in the thickness direction of the substrate are defined as the first surface and the second surface, and when the first metal layer is covered on the first surface and the second surface, the cavity on the second surface forms a circuit structure; wherein the shape of the first metal layer on the second surface corresponds to the shape of the circuit structure.

[0033] The above arrangement can make the side of the substrate plate for mounting power devices such as chips have a micro-structure cavity inside the circuit structure for heat dissipation. After the circuit is connected with the power devices such as chips, the power devices can be cooled more directly, effectively reducing the thermal resistance, so that higher power density power devices can be packaged in unit volume.

[0034] In a second aspect, the present application provides a packaging substrate with a micro-structure cavity, comprising:

[0035] A substrate plate, the substrate plate has a first metal layer.

[0036] A second metal layer, the second metal layer is formed on the first metal layer in the form of electroplating; wherein the second metal layer comprises a plurality of spaced column structures and a frame structure surrounding the outer periphery of the plurality of column structures.

[0037] A metal cover plate is disposed on the second metal layer, and the metal cover plate, the frame structure and the first metal layer jointly form the cavity.

[0038] A phase change medium is filled in the cavity.

[0039] The packaging substrate with the micro-structure cavity provided by the present application can effectively reduce the thermal resistance of the packaging substrate to conduct the heat of the power device to the heat dissipation device, so that a higher power density power device can be packaged in a unit volume.

[0040] In some embodiments of the second aspect of the present application, the substrate board has cavities on both surfaces in the thickness direction, and the cavities are filled with phase change media; the cavity on one surface in the thickness direction of the substrate board forms the circuit structure.

[0041] The above arrangement can make the circuit structure on the side of the substrate board for mounting the chip and other power devices have micro-structure cavities for heat dissipation, and the circuit can more directly dissipate the heat of the power device after being connected with the chip and other power devices, effectively reducing the thermal resistance, so that a higher power density power device can be packaged in a unit volume. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below, and it should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0043] Figure 1 A flow chart of the preparation method of the packaging substrate with the micro-structure cavity provided by the present application is shown.

[0044] Figure 2 A schematic diagram of forming the second metal layer on the first metal layer in the first example provided by the present application is shown.

[0045] Figure 3 A schematic diagram of forming the second metal layer on the first metal layer in the second example provided by the present application is shown.

[0046] Figure 4 A schematic diagram of forming the metal cover plate on the second metal layer in the first example provided by the present application is shown.

[0047] Figure 5 A schematic diagram of closing the cavity in the first example provided by the present application is shown.

[0048] Figure 6A schematic view of the closed chamber in the third example provided in the present application is shown.

[0049] Icon: 100 - substrate; 200 - first metal layer; 300 - second metal layer; 310 - column structure; 320 - frame structure; 321 - phase change medium injection port; 330 - perfusion channel; 331 - pressure welding site; 400 - metal cover plate; 410 - pressure welding seal; 500 - third metal layer; 600 - VC; 700 - HP. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below. If specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturers are used. If the reagents or instruments used are not specified by the manufacturers, they are all conventional products that can be purchased on the market.

[0051] Figure 1 A flow chart of the preparation method of the packaging substrate with a micro-structured chamber provided in the present application is shown. Please refer to Figure 1 The preparation method of the packaging substrate with a micro-structured chamber includes:

[0052] S10, providing a substrate plate with a first metal layer 200.

[0053] The two sides of the substrate plate in the packaging substrate in the thickness direction are respectively used for setting the heat dissipation device and the power device, and the side provided with the power device also needs to be provided with a circuit structure.

[0054] In the present application, the first metal layer 200 is the basis for forming the micro-structured chamber (i.e. the heat dissipation device). The substrate plate includes a substrate 100 and a first metal layer 200 covering the surface of the substrate 100.

[0055] In the present application, the substrate 100 has the first metal layer 200 on at least one surface in the thickness direction. "The substrate 100 has the first metal layer 200 on at least one surface in the thickness direction" means that the surface of the substrate 100 for setting the heat dissipation device has the first metal layer 200; or, the surface of the substrate 100 for setting the heat dissipation device and the surface for setting the power device both have the first metal layer 200.

[0056] In the present application, the material of the substrate 100 is a ceramic material. The ceramic material has high thermal conductivity, good insulation performance and stable physical and chemical properties; the thermal expansion coefficient of the ceramic material is small and close to the thermal expansion coefficient of the power device such as a chip; and the ceramic material has a certain rigidity, which is conducive to avoiding the phenomenon that the deformation of the substrate plate caused by the change of cold and hot temperature during electroplating affects the shape of the microstructure in the chamber, and thus is conducive to making the heat source quickly spread to the entire substrate, thereby greatly reducing the thermal resistance.

[0057] For example, the ceramic material includes at least one of a metal oxide, a metal nitride, and a non-metal nitride. The metal oxide can be selected from Al2O3, the metal nitride can be selected from AlN, and the non-metal nitride can be selected from Si3N4. The ceramic material is not limited to the above-mentioned substances, and the present application is not limited thereto.

[0058] In the present application, the thickness of the first metal layer 200 is 0.2-2 μm, which is beneficial to the stability of the structure of the subsequently formed second metal layer 300.

[0059] For example, the thickness of the first metal layer 200 can be 0.2 μm, 0.5 μm, 0.7 μm, 1 μm, 1.5 μm, or 2 μm, etc.

[0060] Further, in the present application, since the material of the substrate 100 is a ceramic material, the method for forming the first metal layer 200 on the substrate 100 includes forming the first metal layer 200 on the surface of the substrate 100 by sputtering or vapor deposition. The sputtering or vapor deposition can realize the formation of the first metal layer 200 on the insulating substrate 100, and make the connection between the substrate 100 and the first metal layer 200 stronger, thereby being beneficial to improving the structural stability of the packaging substrate with micro-structured cavities prepared by one-piece molding.

[0061] For example, when the first metal layer 200 is formed on the surface of the substrate 100 by vapor deposition, it can be chemical vapor deposition (CVD) or physical vapor deposition (PVD), and the present application is not limited thereto.

[0062] In the embodiments of the present application, the method for forming the first metal layer 200 on the substrate 100 includes sputtering or vapor depositing 200-500 nm of titanium layer and 200-1500 nm of copper layer on the substrate 100 in sequence to form a first metal layer 200 of 1-2 μm.

[0063] Further, in some feasible embodiments, before forming the first metal layer 200 on the surface of the substrate 100, the substrate 100 is also subjected to cleaning pretreatment. The cleaning pretreatment includes alkaline washing, water washing, acid washing, water washing, and drying treatment of the substrate 100 to remove oil, oxidation, and impurities.

[0064] When the substrate 100 has the first metal layer 200 on both surfaces in the thickness direction, the micro-structured cavities of one surface of the substrate 100 in the thickness direction are used to form the circuit structure; in this case, the shape of the first metal layer 200 corresponds to the shape of the circuit structure, and the material of the substrate 100 is a ceramic material or the like.

[0065] S20, electroplating a second metal layer 300 on the first metal layer 200 to form a plurality of column structures 310 and a frame structure 320 surrounding the plurality of column structures 310.

[0066] As described above, the first metal layer 200 is formed on at least one surface of the substrate 100 in the thickness direction, which means that the surface of the substrate 100 for arranging the heat dissipation device has the first metal layer 200, or the surface of the substrate 100 for arranging the heat dissipation device and the surface of the substrate 100 for arranging the power device both have the first metal layer 200.

[0067] In this application, the first example is defined as "forming the first metal layer 200 on the surface of the substrate 100 for arranging the heat dissipation device", and the second example is defined as "forming the first metal layer 200 on the surface of the substrate 100 for arranging the power device".

[0068] Figure 2 The schematic diagram of forming the second metal layer 300 on the first metal layer 200 in the first example provided by the present application is shown, Figure 3 The schematic diagram of forming the second metal layer 300 on the first metal layer 200 in the second example provided by the present application is shown, please refer to Figure 2 and Figure 3 The second metal layer 300 includes a plurality of column structures 310 and a frame structure 320 surrounding the plurality of column structures 310; the plurality of column structures 310 are used to form capillary structures in the micro-structure cavity to achieve heat conduction and heat dissipation. The frame structure 320 is provided with a phase change medium injection port 321 for subsequent injection of phase change medium into the cavity, so as to facilitate the heat conduction and heat dissipation of the phase change medium in the micro-structure cavity.

[0069] In the second example, the edge of the frame structure 320 in the second metal layer 300 is the edge of the circuit structure, so that the micro-structure cavity itself constitutes the circuit structure, and the side of the substrate plate for mounting the power device such as a chip has a micro-structure cavity inside the circuit structure. After the circuit is connected with the power device such as a chip, the power device can be directly cooled, the thermal resistance is effectively reduced, and a higher power density power device can be packaged in a unit volume.

[0070] Further, in this application, the second metal layer 300 further includes a filling channel 330 arranged inside the area surrounded by the frame structure 320 and communicating with the phase change medium injection port 321, which facilitates the filling of the phase change medium and the subsequent sealing of the cavity.

[0071] The second metal layer 300 is formed on the first metal layer 200, and the second metal layer 300 including a plurality of spaced pillar structures 310 and a frame structure 320 surrounding the plurality of pillar structures 310 is formed on the substrate plate by electroplating addition, which can effectively form the pillar structures 310 with high specific surface area, effectively control the height of the pillar structures 310 and the frame structure 320 on the first metal layer 200, and particularly form fine structures with the height of the pillar structures 310 and the frame structure 320 on the first metal layer 200 less than 100 μm; and effectively control the shape of the pillar structures 310 and the frame structure 320, so that the application range of the prepared packaging substrate is wider.

[0072] It should be noted that the number of the pillar structures 310 in the second metal layer 300, the distribution gap between the plurality of pillar structures 310, the height of the pillar structures 310, the shape of the pillar structures 310 and the shape of the frame structure 320 are not limited, and the above settings can be adjusted according to actual conditions.

[0073] The step of forming the second metal layer 300 includes: partially shielding the first metal layer 200 by an insulating material to form a first pattern area exposing the first metal layer 200, and then electroplating the substrate plate to thicken the first metal layer 200 of the first pattern area to obtain the second metal layer 300; wherein the first pattern area includes a pattern area corresponding to the pillar structures 310 and the frame structure 320. Between the subsequent step of forming a metal cover plate and the step of pouring the phase change medium into the cavity, the insulating material is removed.

[0074] In the above manner, the second metal layer 300 including a plurality of spaced pillar structures 310 and a frame structure 320 surrounding the plurality of pillar structures 310 can be effectively formed by electroplating.

[0075] In the present application, the step of forming the second metal layer 300 on the first metal layer 200 includes: covering the first metal layer 200 with a first exposure and development film, exposing the first metal layer 200 by exposure and development to obtain a first pattern area; and then electroplating the substrate plate to thicken the first metal layer 200 of the first pattern area to obtain the second metal layer 300; wherein the first pattern area includes a pattern area corresponding to the pillar structures 310 and the frame structure 320.

[0076] By using the principle of exposure and development, the to-be-plated pattern can be effectively formed, and the second metal layer 300 including a plurality of spaced pillar structures 310 and a frame structure 320 surrounding the plurality of pillar structures 310 can be formed by electroplating.

[0077] Further, covering the first exposure and development film on the first metal layer 200 also includes roughening the surface of the first metal layer 200, so that the first exposure and development film can be stably attached to the surface of the first metal layer 200.

[0078] It should be noted that in the present application, the steps of covering the first exposure and development film on the first metal layer 200 and electroplating the substrate plate to thicken the first metal layer 200 of the first pattern area can be repeated multiple times until the height of the column structure 310 and the frame structure 320 reaches the preset height; in addition, due to the use of the first exposure and development film, subsequent steps of forming the metal cover plate 400 and filling the phase change medium into the cavity also include removing the first exposure and development film inside and outside the cavity.

[0079] When the first metal layer 200 is formed only on the surface of the substrate plate for setting the heat dissipation device, the surface of the substrate plate for setting the power device can be pre-provided with a circuit structure, or the circuit can also be formed on the surface of the substrate plate for setting the power device by exposure and development and electroplating additive, which is not limited in the present application.

[0080] The third example defines the scheme of "forming the heat pipe and the vacuum cavity heat spreader on the surface of the substrate 100 for setting the heat dissipation device at the same time", in the third example, the surface of the first metal layer 200 is divided into a first area (not shown in the figure) and a second area (not shown in the figure), the second metal layer 300 includes a frame structure 320 surrounding the edge of the first metal layer 200, the column structure 310 is arranged in the first area, the column structure 310 is not arranged in the second area, and the phase change medium injection port 321 is arranged on the frame structure 320 in the second area. The second metal layer 300 on the first area is used to form a vacuum cavity heat spreader (VC), and the second metal layer 300 on the second area is used to form a heat pipe (HP), that is, the phase change medium injection port 321 is arranged on the heat pipe.

[0081] S30, forming a metal cover plate 400 on the second metal layer 300, so that the metal cover plate 400, the frame structure 320 and the first metal layer 200 together constitute a cavity.

[0082] Figure 4 The schematic diagram of forming the metal cover plate 400 on the second metal layer 300 in the first example provided by the present application is shown, please refer to Figures 2 to 4 , the metal cover plate 400 is covered on the second metal layer 300, so that the metal cover plate 400, the frame structure 320 and the first metal layer 200 together constitute a cavity with microstructure.

[0083] In the present application, the step of forming the metal cover plate 400 comprises: forming a third metal layer 500 on the second metal layer 300 by physical vapor deposition (PVD), covering the second exposure and development film on the third metal layer 500, exposing and developing to obtain a second pattern area covering the third metal layer; etching the uncovered area of the third metal layer 500, and removing the second exposure and development film. Then cover the third exposure and development film on the third metal layer 500, expose and develop to expose the third pattern area of the third metal layer 500, then electroplate the third metal layer 500 to thicken the third metal layer 500 of the third pattern area, remove the third exposure and development film to obtain the metal cover plate 400; wherein, the second pattern area and the third pattern area are both pattern areas corresponding to the edges of the frame structure 320.

[0084] As an example, the step of removing the second exposure and development film comprises physical polishing treatment.

[0085] The step of forming the metal cover plate 400 can also comprise: forming a third metal layer 500 on the second metal layer 300 by physical vapor deposition (PVD); using an insulating material to partially shield the third metal layer 500 and form a second pattern area covering the third metal layer 500, etching the uncovered area of the third metal layer 500; then using an insulating material to partially shield the third metal layer 500 and form a third pattern area exposing the third metal layer 500, then electroplating the third metal layer 500 to thicken the third metal layer 500 of the third pattern area to obtain the metal cover plate 400; wherein, the second pattern area and the third pattern area are both pattern areas corresponding to the edges of the frame structure 320.

[0086] In other possible embodiments, the step of forming the metal cover plate 400 can also comprise: directly welding the metal cover plate 400 on the second metal layer 300. As an example, the welding method can be straight welding, laser welding, resistance welding, ultrasonic welding, etc.

[0087] Further, the shape of the metal cover plate 400 directly welded on the second metal layer 300 is consistent with the edge shape of the frame structure 320 of the second metal layer 300.

[0088] Using the preparation method provided in the present application, an integrated preparation of a packaging substrate with a micro-structure cavity (i.e. a heat dissipation device) is realized, without the need for connecting the substrate plate and the VC through TIM, effectively avoiding the case that the thermal resistance between the substrate plate and the VC is large due to the setting of the TIM.

[0089] As shown in the foregoing, when the first metal layer 200 is formed on the surface of the substrate plate for arranging the power device, the edge of the frame structure 320 in the second metal layer 300 is the edge of the circuit structure; at this time, the cavity on the surface of the substrate plate for arranging the power device forms the circuit structure.

[0090] It should be noted that in some possible embodiments, before the metal cover plate 400 is formed on the second metal layer 300, the surface of the second metal layer 300 is further subjected to a flattening treatment and a cleaning treatment.

[0091] S40, etching the first metal layer 200 outside the frame structure 320.

[0092] It should be noted that when the metal cover plate 400 is directly welded on the second metal layer 300, the step of etching the first metal layer 200 outside the frame structure 320 (i.e., S40) is performed before S30.

[0093] S50, filling the phase change medium into the cavity through the phase change medium injection port 321, and sealing the cavity.

[0094] The step of filling the phase change medium into the cavity through the phase change medium injection port 321 and sealing the cavity needs to be performed under vacuum conditions.

[0095] In the present application, the phase change medium is pure water. In other possible embodiments, the phase change medium can also be the phase change medium commonly used in the heat plate in the prior art, which is not limited in the present application.

[0096] The method for sealing the cavity includes: pressure welding the surface of the metal cover plate 400 away from the second metal layer 300, so that the phase change medium injection port 321 is not in communication with the cavity. By pressure welding the surface of the metal cover plate 400 away from the second metal layer 300, so that the phase change medium injection port 321 is not in communication with the cavity, no protruding filling structure is formed, and the application range of the prepared packaging substrate is wider.

[0097] The plurality of column structures 310 inside the cavity form a capillary structure, and the cavity contains the phase change medium, so that the prepared packaging substrate with the micro-structured cavity forms a structure with both a heat pipe (HP) and a vacuum cavity heat plate (VC), so that heat can be quickly spread in the three directions of the space xyz to achieve rapid heat conduction, thereby effectively reducing the thermal resistance of the packaging substrate to conduct the heat of the power device to the heat dissipation device, so that a higher power density power device can be packaged in a unit volume.

[0098] Figure 5 A schematic diagram of sealing the cavity in the first example provided by the present application is shown, wherein, Figure 5The dashed line box part of the middle A is a section view, please refer to Figure 4 and Figure 5 Since the filling channel 330 is also arranged in the second metal layer 300, in the present application, the area (i.e. the pressure welding position 331 in the middle A) corresponding to the filling channel 330 at the surface of the metal cover plate 400 away from the second metal layer 300 is pressure welded to form a pressure welding seal 410, so that the filling channel 330 is blocked, and then the phase change medium injection port 321 is not in communication with the cavity. Figure 5

[0099] In other possible embodiments, the area of the metal cover plate 400 away from the surface of the second metal layer 300 corresponding to the phase change medium injection port 321 can be pressure welded, so that the phase change medium injection port 321 is blocked.

[0100] Figure 6 A schematic diagram of a closed cavity in a third example provided by the present application is shown, in Figure 6 the third example, the cavity has a VC 600 and two HPs 700 in communication with the VC 600, and each of the two HPs 700 is provided with a phase change medium injection port 321, at this time, the method for closing the cavity includes: using an external pump (not shown in the figure) to communicate the two phase change medium injection ports 321, so that the cavity is in a closed state with the outside world and the phase change medium in the cavity can circulate. The above setting can make the phase change medium circulate in the cavity, which is beneficial to further improve the heat dissipation effect.

[0101] Further, at this time, the phase change medium can be water or oil, etc.

[0102] It should be noted that in other possible embodiments, it can not be the example as Figure 6 shown, as long as the number of phase change medium injection ports 321 opened on the frame structure 320 is two, the method for closing the cavity can be used: using an external pump to communicate the two phase change medium injection ports 321, so that the cavity is in a closed state with the outside world and the phase change medium in the cavity can circulate.

[0103] Before filling the phase change medium into the cavity, it also includes heat treating the overall structure of the covering metal cover plate 400 to remove stress.

[0104] After the cavity is closed, it also includes passivation treatment (such as forming an organic solder resist film, etc.) or plating other metals on the surface of the packaging substrate forming the micro-structured cavity.

[0105] The present application also provides a packaging substrate with a micro-structured cavity, which is prepared by using the above-mentioned preparation method of the packaging substrate.

[0106] ​The application also provides a packaging substrate with a micro-structured cavity, comprising:

[0107] a substrate plate having a first metal layer.

[0108] a second metal layer formed on the first metal layer in a plated form; wherein the second metal layer comprises a plurality of column structures distributed at intervals and a frame structure surrounding the outer periphery of the plurality of column structures.

[0109] a metal cover plate located on the second metal layer, and the metal cover plate, the frame structure and the first metal layer together constitute a cavity; and

[0110] a phase change medium filled in the cavity. The packaging substrate with a micro-structured cavity provided by the application can effectively reduce the thermal resistance of the packaging substrate to conduct the heat of the power device to the heat dissipation device, so that a higher power density power device can be packaged in a unit volume.

[0111] Further, both surfaces in the thickness direction of the substrate plate have cavities, and the cavities are filled with phase change media; the cavity on one surface in the thickness direction of the substrate plate constitutes a circuit structure.

[0112] The features and performances of the packaging substrate with a micro-structured cavity and the preparation method thereof provided by the application are further described in detail below in combination with embodiments.

[0113] Embodiment 1

[0114] The embodiment provides a packaging substrate with a micro-structured cavity, which is prepared by the following method:

[0115] (1) clean the surface of the substrate, and define the two surfaces in the thickness direction of the substrate as a first surface and a second surface.

[0116] sputter a titanium layer with a thickness of 300 nm and a copper layer with a thickness of 800 nm on the first surface of the substrate in sequence to obtain a first metal layer located on the first surface.

[0117] sputter a titanium layer with a thickness of 200 nm and a copper layer with a thickness of 1000 nm on the second surface of the substrate in sequence to obtain a first metal layer located on the second surface.

[0118] The thickness of the substrate is 0.3 mm, and the material of the substrate is silicon nitride (Si3N4).

[0119] (2) cover the first metal layer on the first surface with a layer of exposure and development film, and expose the first pattern area of the first metal layer after exposure and development; cover the first metal layer on the second surface with a layer of exposure and development film, and expose the circuit shape area of the first metal layer after exposure and development.

[0120] Then the first surface and the second surface of the substrate are electroplated with copper simultaneously to thicken the first metal layer of the first pattern region to obtain a second metal layer with a thickness of 200 μm, and to thicken the first metal layer of the circuit pattern region to obtain a circuit structure with a thickness of 0.1 mm.

[0121] The second metal layer comprises a plurality of column structures, a frame structure surrounding the outer periphery of the plurality of column structures, and a filling channel arranged in the area surrounded by the frame structure; the frame structure is provided with a phase change medium injection port, and the phase change medium injection port is in communication with the filling channel.

[0122] (3) The second metal layer is flattened and cleaned, and then a copper plate (i.e., a metal cover plate) with a shape consistent with the edge shape of the frame structure of the second metal layer is welded on the second metal layer, so that the copper plate, the frame structure, and the first metal layer together form a cavity.

[0123] (4) The exposure and development film inside and outside the cavity is removed. The first metal layer outside the frame structure region of the first surface is etched, and the first metal layer outside the circuit structure region of the second surface is etched. Pure water is filled into the cavity through the phase change medium injection port under vacuum conditions, and the area corresponding to the filling channel on the surface of the metal cover plate away from the second metal layer is pressure welded, so that the filling channel is blocked.

[0124] Example 2

[0125] The present embodiment provides a packaging substrate with a micro-structured cavity, which is prepared by the following method:

[0126] (1) Clean the surface of the substrate, and define the two surfaces in the thickness direction of the substrate as the first surface and the second surface.

[0127] A titanium layer with a thickness of 300 nm and a copper layer with a thickness of 800 nm are sequentially formed on the first surface of the substrate to obtain a first metal layer located on the first surface.

[0128] A titanium layer with a thickness of 200 nm and a copper layer with a thickness of 1000 nm are sequentially sputtered on the second surface of the substrate to obtain a first metal layer located on the second surface.

[0129] The thickness of the substrate is 0.5 mm, and the material of the substrate is aluminum nitride (AlN).

[0130] (2) A first exposure and development film is covered on the first metal layer of the first surface, and after exposure and development, a first pattern region of the first metal layer is exposed; a layer of exposure and development film is covered on the first metal layer of the second surface, and after exposure and development, a circuit pattern region of the first metal layer is exposed.

[0131] Then the first surface and the second surface of the substrate are electroplated with copper simultaneously to thicken the first metal layer of the first pattern region to obtain a second metal layer with a thickness of 200 μm, and to thicken the first metal layer of the circuit pattern region to obtain a circuit structure with a thickness of 0.1 mm.

[0132] The second metal layer comprises a plurality of column structures, a frame structure surrounding the plurality of column structures, and a filling channel arranged in a region surrounded by the frame structure; the frame structure is provided with a phase change medium injection port, and the phase change medium injection port is in communication with the filling channel.

[0133] (3) A third metal layer (material: copper) with a thickness of 1 μm is formed on the second metal layer by PVD; a second exposure and development film is covered on the third metal layer, and a second pattern region covering the third metal layer is obtained by exposure and development; the third metal layer in the uncovered region is etched, and the second exposure and development film is removed. Then a third exposure and development film is covered on the third metal layer, and a third pattern region of the third metal layer is exposed after exposure and development, and then the third metal layer is electroplated with copper to thicken the third metal layer of the third pattern region, the third exposure and development film is removed, and a metal cover plate with a thickness of 100 μm is obtained.

[0134] The second pattern region and the third pattern region are both pattern regions corresponding to the edges of the frame structure.

[0135] (4) The first exposure and development film inside and outside the chamber is removed. The first metal layer outside the frame structure region of the first surface is etched, and the first metal layer outside the circuit structure region of the second surface is etched. Pure water is filled into the chamber through the phase change medium injection port under vacuum condition, and the region corresponding to the filling channel at the surface of the metal cover plate away from the second metal layer is pressure welded, so that the filling channel is blocked.

[0136] Example 3

[0137] The present embodiment provides a packaging substrate with a micro-structured chamber, which is prepared by the following method:

[0138] (1) The surface of the substrate is cleaned, and the two surfaces in the thickness direction of the substrate are defined as the first surface and the second surface. The first surface is used for mounting a heat dissipation device, and the second surface is used for mounting a power device.

[0139] A titanium layer with a thickness of 300 nm and a copper layer with a thickness of 800 nm are sequentially deposited on the first surface of the substrate to obtain a first metal layer located on the first surface.

[0140] A titanium layer with a thickness of 200 nm and a copper layer with a thickness of 1000 nm are sequentially deposited on the second surface of the substrate to obtain a first metal layer located on the second surface.

[0141] The thickness of the substrate is 0.254 mm, and the material of the substrate is silicon nitride (Si3N4).

[0142] (2) Cover the first exposure and development film on the first metal layer of the first surface and the second surface, and expose the first pattern area of the first metal layer after exposure and development; then electroplate copper on the substrate to thicken the first metal layer of the first pattern area, and obtain the second metal layer.

[0143] The second metal layer includes a plurality of column structures, a frame structure surrounding the outer periphery of the plurality of column structures, and a filling channel arranged in the area surrounded by the frame structure; the frame structure is provided with a phase change medium injection port, and the phase change medium injection port is in communication with the filling channel.

[0144] The thickness of the second metal layer on one side for mounting the heat dissipation device is 150 μm. The thickness of the second metal layer on one side for mounting the power device is 150 μm, and the edge of the frame structure on one side for mounting the power device is the edge of the circuit structure.

[0145] (3) Form a third metal layer (material: copper) on the second metal layer by PVD; cover the second exposure and development film on the third metal layer, and expose the second pattern area of the third metal layer after exposure and development; etch the uncovered area of the third metal layer, and remove the second exposure and development film. Then cover the third exposure and development film on the third metal layer, expose the third pattern area of the third metal layer after exposure and development, and then electroplate copper on the third metal layer to thicken the third metal layer of the third pattern area, remove the third exposure and development film, and obtain the metal cover plate.

[0146] The second pattern area and the third pattern area are both pattern areas corresponding to the edge of the frame structure. The thickness of the third metal layer on one side for mounting the heat dissipation device is 1 μm, and the thickness of the metal cover plate on one side for mounting the heat dissipation device is 150 μm. The thickness of the third metal layer on one side for mounting the power device is 1 μm, and the thickness of the metal cover plate on one side for mounting the power device is 150 μm.

[0147] (4) Remove the first exposure and development film inside and outside the chamber. Etch the first metal layer outside the frame structure area of the first surface and the second surface. Fill pure water into the chamber through the phase change medium injection port under vacuum condition, and pressure weld the area corresponding to the filling channel at the surface of the metal cover plate away from the second metal layer, so that the filling channel is blocked.

[0148] In summary, the preparation method of the packaging substrate with a micro-structure chamber provided by the present application can effectively reduce the thermal resistance of the packaging substrate for conducting the heat of the power device to the heat dissipation device, so that a higher power density of the power device can be packaged in a unit volume.

[0149] The above descriptions are only the preferred embodiments of the present application, and are not intended to limit the present application. The present application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for fabricating a packaging substrate with microstructured chambers, characterized in that, The application relates to a method for manufacturing a phase change medium chamber. The method comprises the following steps: providing a substrate plate with a first metal layer; electroplating a second metal layer on the first metal layer; wherein the second metal layer comprises a plurality of column structures and a frame structure surrounding the column structures; the frame structure is provided with a phase change medium injection port; forming a metal cover plate on the second metal layer, so that the metal cover plate, the frame structure and the first metal layer jointly form a cavity; injecting a phase change medium into the cavity through the phase change medium injection port, and sealing the cavity; the substrate plate comprises a ceramic material as a base, and the first metal layer is covered on the base; two surfaces in the thickness direction of the base are defined as a first surface and a second surface; when the first surface and the second surface are both covered with the first metal layer, the cavity on the second surface forms a circuit structure; 2. The method of manufacturing a package substrate according to claim 1, wherein the shape of the first metal layer on the second surface corresponds to the shape of the circuit structure.

3. The method of manufacturing a package substrate according to claim 1, wherein the method for covering the first metal layer on the base comprises the following steps: forming the first metal layer on the surface of the base by sputtering or vapor deposition. the step of forming the second metal layer comprises the following steps: partially shielding the first metal layer with an insulating material to form a first pattern area exposing the first metal layer, and then electroplating the substrate plate to thicken the first metal layer in the first pattern area; the first pattern area comprises a pattern area corresponding to the column structure and the frame structure.

4. The method of manufacturing a package substrate according to claim 3, wherein the step of forming the metal cover plate and the step of injecting the phase change medium into the cavity further comprise the following step: removing the insulating material. the step of forming the second metal layer comprises the following steps: covering a first exposure and development film on the first metal layer, exposing and developing to obtain the first pattern area exposing the first metal layer, and then electroplating the substrate plate to thicken the first metal layer in the first pattern area.

5. The method of manufacturing a package substrate according to claim 4, wherein the step of forming the metal cover plate and the step of injecting the phase change medium into the cavity further comprise the following step: removing the first exposure and development film inside and outside the cavity. the step of forming the metal cover plate comprises the following steps: forming a third metal layer on the second metal layer by physical vapor deposition, covering a second exposure and development film on the third metal layer, exposing and developing to obtain a second pattern area covering the third metal layer, etching the uncovered area of the third metal layer, and then removing the second exposure and development film; 6. The method of manufacturing a package substrate according to claim 5, wherein covering a third exposure and development film on the third metal layer, exposing and developing to obtain a third pattern area exposing the third metal layer, then electroplating the third metal layer to thicken the third metal layer in the third pattern area, removing the third exposure and development film to obtain the metal cover plate; wherein the second pattern area and the third pattern area are both pattern areas corresponding to the edges of the frame structure. the step of removing the first exposure and development film and the step of injecting the phase change medium into the cavity further comprise the following step: etching the first metal layer outside the frame structure area.

7. The method of manufacturing a package substrate according to claim 1 or 3, wherein The step of forming the metal cover plate includes welding the metal cover plate on the second metal layer.

8. The method of manufacturing a package substrate according to claim 7, wherein The method further includes etching the first metal layer outside the frame structure region between the step of forming the second metal layer and the step of forming the metal cover plate.

9. The method of manufacturing a package substrate according to claim 1, wherein The method of sealing the chamber includes pressure welding a surface of the metal cover plate away from the second metal layer so that the phase change medium injection port is not in communication with the chamber.

10. The method of producing a package substrate according to claim 1, wherein The frame structure has two phase change medium injection ports, and the method of sealing the chamber includes using an external pump to communicate the two phase change medium injection ports so that the phase change medium in the chamber can flow in a circulation manner.

11. A package substrate having microcavities, produced by the production method according to any one of claims 1 to 10, characterized in that The method includes: a substrate plate having a first metal layer; a second metal layer formed on the first metal layer in a plating manner; wherein the second metal layer includes a plurality of spaced column structures and a frame structure surrounding the column structures; a metal cover plate on the second metal layer, and the metal cover plate, the frame structure and the first metal layer together form a chamber; and a phase change medium filled in the chamber.

12. The package substrate with microcavities of claim 11, wherein, Both surfaces of the substrate plate in the thickness direction have the chamber, and the chamber is filled with the phase change medium; the chamber on one surface of the substrate plate in the thickness direction constitutes a circuit structure.

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