A composite multilayer wiring board and a method for manufacturing the same

Abstract

This application provides a composite multilayer circuit board and its fabrication method, belonging to the field of circuit board technology. The composite multilayer circuit board includes at least three stacked single-layer circuit boards, which are either ceramic circuit boards or organic circuit boards, and simultaneously include at least one ceramic circuit board and at least one organic circuit board. When a ceramic circuit board is present in the middle or top layer, it is electrically connected to the adjacent lower layer circuit board through a first electrical connection structure including a metal interconnect and a solder connection layer. The remaining adjacent layers are electrically connected through a second electrical connection structure including a through-layer conductor. This application, through the composite stacking of ceramic and organic circuit boards, improves the heat dissipation performance and operational reliability of the multilayer circuit board while maintaining high-density wiring and processing flexibility. Furthermore, by using differentiated interlayer electrical connection structures, it adapts to the differences in the characteristics of different material interfaces, thereby improving the reliability of interlayer electrical connections.

Description

Technical Field

[0001] This invention relates to the field of multilayer circuit board technology, and in particular to a composite multilayer circuit board and its preparation method. Background Technology

[0002] With the rapid development of automotive electronics, communication equipment and aerospace, increasingly higher requirements are being placed on electronic packaging technology, including high heat dissipation performance, high wiring density, miniaturization and high reliability.

[0003] In the field of multilayer circuit boards, traditional printed circuit boards (PCBs) are widely used in various electronic devices due to their mature processing technology and low cost. Through multilayer stacking and microvia interconnection technology, PCBs can achieve high wiring density and small size, meeting the basic requirements of electronic packaging for high density and miniaturization.

[0004] However, the insulating substrate of traditional multilayer PCBs is an organic polymer material, which typically has low thermal conductivity. When supporting devices that generate a lot of heat, such as high-power chips and RF amplifier modules, the heat is difficult to conduct and dissipate in time, easily leading to localized overheating. This causes the PCB operating temperature to rise, which in turn affects the performance of the devices and reduces the long-term reliability of the PCB.

[0005] Therefore, how to improve the heat dissipation performance of multilayer circuit boards to enhance their operational reliability has become a technical problem that needs to be solved in this field. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a composite multilayer circuit board and its preparation method, so as to solve the problem that the heat dissipation performance of the existing multilayer circuit board is insufficient, which leads to reduced reliability when carrying devices with large heat generation.

[0007] To achieve the above and other related objectives, this application provides a composite multilayer circuit board, comprising: At least three layers of stacked circuit boards, each of which is a single-layer structure; The circuit board is a ceramic circuit board or an organic circuit board, and the composite multilayer circuit board includes at least one layer of the ceramic circuit board and at least one layer of the organic circuit board. When a ceramic circuit board is located in the middle or top layer of the composite multilayer circuit board, the ceramic circuit board and its directly adjacent lower circuit board are electrically connected through a first electrical connection structure. The first electrical connection structure includes a metal connector and a solder connection layer. The metal connector is disposed on the ceramic circuit board, and the solder connection layer fixes the metal connector to the circuit pattern of the lower circuit board. The remaining directly adjacent circuit boards are electrically connected through a second electrical connection structure, which includes a conductor that penetrates the layers.

[0008] Optionally, the metal connector is a metal boss.

[0009] Optionally, the metal boss is electroplated onto the circuit pattern of the ceramic circuit board.

[0010] Optionally, the height of the metal boss is between 30μm and 80μm.

[0011] Optionally, the metal boss is a cylinder, and the bottom diameter of the metal boss is between 100μm and 600μm.

[0012] Optionally, the metal boss is disposed on the circuit pattern on the surface of the ceramic circuit board facing the lower circuit board, and the solder connection layer is disposed on the circuit pattern on the surface of the lower circuit board facing the ceramic circuit board, with the metal boss and the solder connection layer corresponding one-to-one.

[0013] Optionally, the metal boss is welded to the solder bonding layer.

[0014] Optionally, the metal boss is polished to an error of less than ±10μm.

[0015] Optionally, the metal boss is made of copper; the solder bonding layer is made of at least one of gold, tin, copper, nickel and silver.

[0016] Optionally, the thickness of the solder bonding layer is between 50 μm and 150 μm.

[0017] Optionally, an adhesive layer is provided between adjacent circuit boards; the adhesive layer has a first through hole at the position corresponding to the first electrical connection structure, and the metal connector and the solder connection layer are disposed in the first through hole; the adhesive layer has a second through hole at the position corresponding to the second electrical connection structure, and the conductor is disposed in the second through hole.

[0018] Optionally, the conductor is made of metal or a metal-resin mixture.

[0019] Optionally, the adhesive layer is made of resin.

[0020] Preferably, the resin is PP.

[0021] Optionally, the ceramic circuit board is selected from silicon nitride ceramic circuit boards, alumina ceramic circuit boards, aluminum nitride ceramic circuit boards, or zirconium oxide ceramic circuit boards.

[0022] Optionally, the ceramic circuit board is a ceramic circuit board that has undergone DPC metal processing.

[0023] Optionally, the organic circuit board is a PCB circuit board.

[0024] On the other hand, this application also provides a method for preparing a composite multilayer circuit board, characterized by comprising the following steps: A circuit board with at least three single-layer structures is provided, wherein the circuit board is a ceramic circuit board or an organic circuit board, and the at least three-layer circuit board simultaneously includes at least one layer of the ceramic circuit board and at least one layer of the organic circuit board; The circuit boards are stacked one by one in a preset order, and the circuit boards are connected between every two adjacent layers. Wherein, when the stacking connection involves a ceramic circuit board located in the middle or top layer and its lower circuit board, a first connection method is used to connect them to form a first electrical connection structure. The first electrical connection structure includes a metal connector and a solder connection layer. The metal connector is disposed on the ceramic circuit board, and the solder connection layer fixes the metal connector to the circuit pattern of the lower circuit board. When the stacked connection involves other adjacent circuit boards, a second connection method is used to form a second electrical connection structure, which includes a conductor that penetrates between layers.

[0025] Optionally, the metal connector is a metal boss.

[0026] Optionally, the first connection method includes: Take a ceramic circuit board, and form the metal boss on the circuit pattern on one side of the ceramic circuit board through an electroplating process. The metal boss is electroplated and formed on the circuit pattern of the ceramic circuit board. Take a lower circuit board adjacent to the ceramic circuit board, provide an adhesive layer on the surface of the lower circuit board facing the ceramic circuit board, and process the adhesive layer to form a first through hole. The first through hole exposes the circuit pattern of the lower circuit board. Then, solder is pre-placed on the exposed circuit pattern to form a solder connection layer. The metal bosses are aligned one by one with the solder connection layer, and the electrical structural connection between the ceramic circuit board and the lower circuit board is completed through the welding step.

[0027] Optionally, the solder pre-placement process is a ball-planting process, a printing process, or a spraying process; the processing process of the first through hole is laser cutting or machining.

[0028] Optionally, the welding step adopts a vacuum hot-press welding process or a reflow welding process, with a welding vacuum degree ≤10 Pascals. During the welding process, the temperature is raised from room temperature to 150℃~350℃ at a heating rate of 0.5℃ / s~4℃ / s, followed by holding at that temperature for 3min~10min.

[0029] Optionally, the metal boss is made of copper; the solder bonding layer is made of at least one of gold, tin, copper, nickel and silver.

[0030] Optionally, the height of the metal boss is between 30μm and 80μm; the metal boss is a cylinder, and the bottom diameter of the metal boss is between 100μm and 600μm.

[0031] Optionally, the thickness of the solder bonding layer is between 50 μm and 150 μm.

[0032] Optionally, the second connection method includes: An adhesive layer is placed between two adjacent circuit boards. After hot pressing, a second through hole is formed on the adhesive layer by laser drilling or mechanical drilling. The second through hole is filled with metal or a metal-resin mixture to form the conductor.

[0033] Optionally, the conditions for the hot pressing step are: hot pressing temperature between 150℃ and 250℃, and holding time between 60min and 180min.

[0034] Optionally, before stacking layer by layer, the method further includes: drilling positioning holes or making alignment marks on the bottom circuit board as alignment references for subsequent stacking calibration and positioning steps.

[0035] As described above, the composite multilayer circuit board and its fabrication method provided in this application have the following beneficial effects: The composite multilayer circuit board provided in this application stacks ceramic circuit boards and organic circuit boards, utilizing the high thermal conductivity of ceramic materials to effectively conduct and dissipate heat generated by high-power devices, thereby reducing the operating temperature of the circuit board and improving its heat dissipation performance, thus enhancing its reliability when carrying devices with high heat generation. Simultaneously, this composite structure achieves the heat dissipation advantages of ceramic circuit boards while retaining the advantages of organic circuit boards in high-density wiring, multilayer interconnection, and processing flexibility, avoiding the problems of high cost and limited wiring density associated with using all-ceramic multilayer boards. Furthermore, this application employs different first and second electrical connection structures for electrical connections between the ceramic circuit board and its underlying circuit board, as well as other interlayer interfaces. This differentiated electrical connection design can adapt to the differences in thermal expansion coefficients, stress distribution, and other characteristics of different material interfaces, contributing to improved reliability of interlayer electrical connections and long-term stability of the overall structure.

[0036] The method for preparing composite multilayer circuit boards provided in this application employs a first connection method and a second connection method for differentiated connections between the ceramic circuit board and its lower circuit board, as well as between other adjacent circuit boards. This allows the electrical connection structure at the interface of different materials to adapt to their respective thermal expansion characteristics and stress distribution characteristics, simplifying the manufacturing process while ensuring the reliability of interlayer electrical connections and improving the product yield. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall structure of the composite multilayer circuit board according to Embodiment 1 of this application.

[0038] Figure 2 This is an exploded view of the composite multilayer circuit board according to Embodiment 1 of this application.

[0039] Figure 3 This is a schematic diagram of the overall structure of the composite multilayer circuit board according to Embodiment 2 of this application.

[0040] Figure 4 This is an exploded view of the composite multilayer circuit board of Embodiment 2 of this application.

[0041] Figure 5 This is a schematic diagram of the overall structure of the composite multilayer circuit board according to Embodiment 3 of this application.

[0042] Figure 6 This is an exploded view of the composite multilayer circuit board of Embodiment 3 of this application.

[0043] Figure 7 This is a schematic diagram of the overall structure of the composite multilayer circuit board according to Embodiment 4 of this application.

[0044] Figure 8 This is an exploded view of the composite multilayer circuit board of Embodiment 4 of this application.

[0045] Figure 9 This is a schematic diagram of the overall structure of the composite multilayer circuit board according to Embodiment 5 of this application.

[0046] Figure 10 This is an exploded view of the composite multilayer circuit board of Embodiment 5 of this application.

[0047] Component designation explanation 100, Ceramic circuit board; 110, Ceramic circuit board circuit pattern; 120, First metal pillar; 200, Organic circuit board; 210, Organic circuit board circuit pattern; 220, Second metal pillar; 300, First electrical connection structure; 310, Metal connector; 320, Solder connection layer; 410, Conductor; 500, Adhesive layer. Detailed Implementation

[0048] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present application.

[0049] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. Example 1

[0050] This embodiment provides a composite multilayer circuit board, such as Figure 1 and Figure 2 As shown, the composite multilayer circuit board includes eight layers of circuit boards stacked sequentially. The first and eighth layers are ceramic circuit boards 100; the second to seventh layers are organic circuit boards 200. Since the second to seventh layers are all of the same type of circuit board, therefore... Figure 1 and Figure 2 In the diagram, only the structure of the 3-layer organic circuit board 200 is shown for the 2nd to 7th layers of the circuit board; an adhesive layer 500 is provided between adjacent circuit boards.

[0051] The ceramic circuit board 100 is a silicon nitride ceramic circuit board that has undergone DPC metallization treatment. The Ti / Cu seed layer thickness of the DPC metallization layer is 100nm / 1000nm, and the electroplated copper layer thickness is 50μm. Ceramic circuit board circuit patterns 110 are provided on both the upper and lower surfaces of the ceramic circuit board 100. A first through-hole is provided between the upper and lower surfaces, and a first metal pillar 120 is provided in the first through-hole to realize the electrical connection between the ceramic circuit board circuit patterns 110 on the upper and lower surfaces of the ceramic circuit board 100.

[0052] Organic circuit board 200 is a PCB circuit board. Organic circuit board circuit patterns 210 are provided on both the upper and lower surfaces of organic circuit board 200. A second through hole is provided between the upper and lower surfaces, and a second metal pillar 220 is provided in the second through hole to realize the electrical connection between the organic circuit board circuit patterns 210 on the upper and lower surfaces of this organic circuit board 200.

[0053] Second through-holes are provided within the adhesive layer 500 between the first to seventh circuit board layers. These second through-holes can be formed by mechanical drilling. A conductor 410 is disposed within each second through-hole. The conductor 410 can be filled into the second through-hole by electroplating. The conductor 410 is made of a metal with high thermal and electrical conductivity, such as copper, or a metal-resin mixture. The conductor 410 enables electrical connection between the circuit patterns of adjacent circuit boards.

[0054] A first through-hole is provided on the adhesive layer 500 between the 7th and 8th layer circuit boards. The first through-hole can be formed by laser processing. A solder bonding layer 320 is provided in the first through-hole. The solder bonding layer 320 is pre-formed on the circuit pattern on the surface of the 7th layer organic circuit board 200 near the 8th layer ceramic circuit board 100 by ball bonding. The solder bonding layer 320 has a thickness of 150μm and is made of tin-silver-copper alloy.

[0055] Metal connectors 310, specifically metal bosses, are provided on the circuit pattern of the 8th layer ceramic circuit board 100 near the 7th layer organic circuit board 200. The metal bosses are made of copper and are formed using photolithography and electroplating processes. They have a height of 30μm to 80μm, are cylindrical in shape with a base diameter of 100μm, and are polished to an error of less than ±10μm. The metal bosses are then welded to the solder connection layer 320 using vacuum reflow soldering to achieve electrical connection between the circuit patterns of the 7th layer organic circuit board 200 and the 8th layer ceramic circuit board 100.

[0056] The adhesive layer 500 has a thickness of 200μm and is made of PP.

[0057] This embodiment also provides a method for preparing a composite multilayer circuit board, including the following steps: S1. Take the silicon nitride ceramic circuit board after DPC metallization treatment, where the Ti / Cu seed layer thickness of the DPC metallization layer is 100nm / 1000nm, the electroplated copper layer thickness is 50μm, and positioning holes are reserved outside the stacking area. After alignment with the positioning holes, PP layer and PCB circuit board are stacked sequentially on the upper surface of DPC silicon nitride ceramic circuit board. The PP layer thickness is 200μm. Hot pressing is performed under the following conditions: 230℃, 60min. Using mechanical drilling, holes are drilled into the upper surface of the covered PCB circuit board and PP layer to form the second through hole. Then, the hole is filled by electroplating (the hole can be filled with metal or metal resin) to complete the electrical connection.

[0058] S2. After aligning with the positioning holes, stack the PP layer and another PCB on the upper surface of the PCB in sequence, and perform hot pressing. The hot pressing conditions are: 230℃, 60min. Use mechanical drilling to drill holes in the other PCB and PP layer to the upper surface of the PCB (i.e., form the second through hole). Then fill the hole with electroplating (the hole can be filled with metal or metal resin) to complete the electrical connection.

[0059] S3. Repeat this process multiple times until the number of PCB circuit board layers is 6. Use a lamination bonding method to attach PP insulating adhesive to the upper surface of the top PCB circuit board with a thickness of 200μm. Use laser processing to remove excess insulating adhesive from the circuit pattern on the upper surface of the PCB circuit board (i.e., form the first through hole). Then, use a ball-planting method to complete the solder pre-fabrication on the circuit pattern on the upper surface of the top PCB circuit board to form a solder connection layer with a thickness of 150μm.

[0060] S4. Take the silicon nitride ceramic circuit board after DPC metallization treatment. The thickness of the Ti / Cu seed layer of the DPC metallization layer is 100nm / 1000nm, and the thickness of the electroplated copper layer is 50μm. The metal bosses on the circuit pattern on the lower surface of the DPC silicon nitride ceramic circuit board are electroplated using photolithography and electroplating. The height of the metal bosses is 30μm to 80μm, and the shape of the metal bosses is cylindrical with a bottom diameter of 100μm. The metal bosses are polished to ensure that the error is less than ±10μm. Optical calibration is performed using the positioning holes on the DPC metallization layer. A pressure of 25MPa is applied, and the metal bosses are soldered to the solder connection layer using vacuum reflow soldering. The soldering vacuum is less than 10Pa. The temperature is gradually increased from room temperature to 320℃ at a heating rate of 3℃ / s and held at 320℃ for 10min. Then, it is naturally cooled to room temperature at a cooling rate of less than 1℃ / s. The product manufacturing process is complete, resulting in a composite multilayer circuit board consisting of 8 layers, formed by PCB circuit board and DPC silicon nitride ceramic circuit board.

[0061] Tests showed that the heat dissipation performance of the composite multilayer circuit board in this embodiment is 10% better than that of a PCB multilayer circuit board with the same number of layers. Example 2

[0062] This embodiment also provides a composite multilayer circuit board, such as Figure 3 and Figure 4 As shown, the composite multilayer circuit board includes eight layers of circuit boards stacked sequentially. The first, third, and eighth layers are ceramic circuit boards 100; the second, fourth, and seventh layers are all organic circuit boards 200. Since the fourth to seventh layers are all of the same type of circuit board, therefore... Figure 3 and Figure 4In the diagram, only the structure of a single organic circuit board 200 is shown for the 4th to 7th layers of the circuit board; an adhesive layer 500 is provided between adjacent circuit boards.

[0063] The ceramic circuit board 100 is a silicon nitride ceramic circuit board that has undergone DPC metallization treatment. The Ti / Cu seed layer thickness of the DPC metallization layer is 100nm / 1000nm, and the electroplated copper layer thickness is 50μm. Ceramic circuit board circuit patterns 110 are provided on both the upper and lower surfaces of the ceramic circuit board 100. A first through-hole is provided between the upper and lower surfaces, and a first metal pillar 120 is provided in the first through-hole to realize the electrical connection between the ceramic circuit board circuit patterns 110 on the upper and lower surfaces of the ceramic circuit board 100.

[0064] Organic circuit board 200 is a PCB circuit board. Organic circuit board circuit patterns 210 are provided on both the upper and lower surfaces of organic circuit board 200. A second through hole is provided between the upper and lower surfaces, and a second metal pillar 220 is provided in the second through hole to realize the electrical connection between the organic circuit board circuit patterns 210 on the upper and lower surfaces of this organic circuit board 200.

[0065] Second through-holes are provided in the adhesive layer 500 between the first and second circuit boards, and in the adhesive layer 500 between the third and seventh circuit boards. These second through-holes can be formed by mechanical drilling. A conductor 410 is disposed within each second through-hole. The conductor 410 can be filled into the second through-hole by electroplating. The conductor 410 is made of a metal with high thermal and electrical conductivity, such as copper, or a metal-resin mixture. The conductor 410 enables electrical connection between the circuit patterns of adjacent circuit boards.

[0066] A first through-hole is provided in the adhesive layer 500 between the second and third layers of the circuit board, and in the adhesive layer 500 between the seventh and eighth layers of the circuit board. The first through-hole can be formed by laser processing. A solder connection layer 320 is provided in the first through-hole. The solder connection layer 320 is pre-formed on the circuit pattern on the upper surface of the second layer organic circuit board 200 and the upper surface of the seventh layer organic circuit board 200 by ball bonding. The solder connection layer 320 is spherical in shape with a diameter of 100μm and is made of tin-silver-copper alloy.

[0067] Metal connectors 310, specifically metal bosses, are provided on the circuit patterns on the lower surfaces of the third-layer ceramic circuit board 100 and the eighth-layer ceramic circuit board 100. The metal bosses are made of copper and are formed using photolithography and electroplating processes. Their height ranges from 30μm to 80μm, and after polishing, the error is less than ±10μm. The diameter of the metal bosses on the lower surface of the third-layer ceramic circuit board 100 is 100μm, and the diameter of the metal bosses on the lower surface of the eighth-layer ceramic circuit board 100 is 350μm. The metal bosses are soldered to the solder connection layer 320 using vacuum reflow soldering to achieve electrical connections between the circuit patterns of the second-layer organic circuit board 200 and the third-layer ceramic circuit board 100, and between the seventh-layer organic circuit board 200 and the eighth-layer ceramic circuit board 100.

[0068] The adhesive layer 500 has a thickness of 200μm and is made of PP.

[0069] This embodiment also provides a method for preparing a composite multilayer circuit board, including the following steps: S1. Take the silicon nitride ceramic circuit board after DPC metallization treatment, where the Ti / Cu seed layer thickness of the DPC metallization layer is 100nm / 1000nm, the electroplated copper layer thickness is 50μm, and positioning holes are reserved outside the stacking area. After alignment with the positioning holes, PP layer and PCB circuit board are stacked sequentially on the upper surface of DPC silicon nitride ceramic circuit board. The PP layer thickness is 200μm. Hot pressing is performed under the following conditions: 230℃, 60min. Using mechanical drilling, holes are drilled into the upper surface of the covered PCB circuit board and PP layer to form the second through hole. Then, the hole is filled by electroplating (the hole can be filled with metal or metal resin) to complete the electrical connection.

[0070] S2. Stack a PP layer with a thickness of 200μm on the upper surface of the PCB circuit board and perform hot pressing. The hot pressing conditions are: 230℃, 60min. Use mechanical drilling to drill holes in the covered PP layer to the metal circuit layer on the upper surface of the PCB circuit board (i.e., form the first through hole). Then, use a printed ball placement method to pre-fabricate SnAgCu solder at the hole position to form a solder connection layer with a diameter of 100μm.

[0071] S3. Take the silicon nitride ceramic circuit board after DPC metallization treatment. The thickness of the Ti / Cu seed layer of the DPC metallization layer is 100nm / 1000nm, and the thickness of the electroplated copper layer is 50μm. The metal bosses on the circuit pattern on the lower surface of the DPC silicon nitride ceramic circuit board are electroplated using photolithography and electroplating. The height of the metal bosses is 30μm to 80μm, and the shape of the metal bosses is cylindrical with a bottom diameter of 100μm. The metal bosses are polished to ensure that the error is less than ±10μm. Optical calibration is performed using the positioning holes on the DPC metallization layer. A pressure of 25MPa is applied, and the metal bosses are welded to the solder connection layer using vacuum reflow soldering. The welding vacuum is less than 10Pa. The temperature is gradually increased from room temperature to 300℃ at a heating rate of 1.5℃ / s and held at 300℃ for 10min. Then, it is naturally cooled to room temperature at a cooling rate of less than 1℃ / s to complete the soldering.

[0072] S4. After positioning and alignment, stack the PP layer and another PCB circuit board sequentially on the upper surface of the DPC silicon nitride ceramic circuit board, and perform hot pressing. The hot pressing conditions are: 230℃, 60min. Use mechanical drilling to drill holes in the other PCB circuit board and PP layer to the upper surface of the PCB circuit board (i.e., form the second through hole). Then, fill the hole with electroplating (the hole can be filled with metal or metal resin) to complete the electrical connection.

[0073] S5. Repeat this process multiple times until the number of intermediate circuit board layers is 6. Use a lamination method to attach PP insulating adhesive to the upper surface of the top PCB circuit board with a thickness of 200μm. Use laser processing to remove excess insulating adhesive from the circuit pattern on the upper surface of the PCB circuit board (i.e., form the first through hole). Then, use a ball-planting method to complete the solder pre-fabrication on the circuit pattern on the upper surface of the top PCB circuit board to form a solder connection layer with a thickness of 100μm.

[0074] S6. Take the silicon nitride ceramic circuit board after DPC metallization treatment. The thickness of the Ti / Cu seed layer of the DPC metallization layer is 100nm / 1000nm, and the thickness of the electroplated copper layer is 50μm. The metal bosses on the circuit pattern on the lower surface of the DPC silicon nitride ceramic circuit board are electroplated using photolithography and electroplating. The height of the metal bosses is 30μm to 80μm, and the shape of the metal bosses is cylindrical with a bottom diameter of 350μm. The metal bosses are polished to ensure that the error is less than ±10μm. Optical calibration is performed using the positioning holes on the DPC metallization layer. A pressure of 50MPa is applied, and the metal bosses are welded to the solder connection layer using vacuum reflow soldering. The soldering vacuum is less than 10Pa. The temperature is gradually increased from room temperature to 300℃ at a heating rate of 1.5℃ / s and held at 300℃ for 10min. Then, it is naturally cooled to room temperature at a cooling rate of less than 1℃ / s. The product manufacturing process is complete, resulting in a composite multilayer circuit board consisting of 8 layers, formed by PCB circuit board and DPC silicon nitride ceramic circuit board.

[0075] Tests showed that the heat dissipation performance of the composite multilayer circuit board in this embodiment is 15% better than that of a PCB multilayer circuit board with the same number of layers. Example 3

[0076] This embodiment also provides a composite multilayer circuit board, such as Figure 5 and Figure 6 As shown, the composite multilayer circuit board includes eight layers of circuit boards stacked sequentially. The first layer is a ceramic circuit board 100; the second to eighth layers are all organic circuit boards 200. Since the second to eighth layers are all of the same type of circuit board, therefore... Figure 5 and Figure 6 In the diagram, only the structure of the 3-layer organic circuit board 200 is shown for the 2nd to 8th layers of the circuit board; an adhesive layer 500 is provided between adjacent circuit boards.

[0077] The ceramic circuit board 100 is a silicon nitride ceramic circuit board that has undergone DPC metallization treatment. The Ti / Cu seed layer thickness of the DPC metallization layer is 100nm / 1000nm, and the electroplated copper layer thickness is 50μm. Ceramic circuit board circuit patterns 110 are provided on both the upper and lower surfaces of the ceramic circuit board 100. A first through-hole is provided between the upper and lower surfaces, and a first metal pillar 120 is provided in the first through-hole to realize the electrical connection between the ceramic circuit board circuit patterns 110 on the upper and lower surfaces of the ceramic circuit board 100.

[0078] Organic circuit board 200 is a PCB circuit board. Organic circuit board circuit patterns 210 are provided on both the upper and lower surfaces of organic circuit board 200. A second through hole is provided between the upper and lower surfaces, and a second metal pillar 220 is provided in the second through hole to realize the electrical connection between the organic circuit board circuit patterns 210 on the upper and lower surfaces of this organic circuit board 200.

[0079] All adhesive layers 500 have a second through-hole, which can be formed by mechanical drilling. A conductor 410 is disposed within each second through-hole. The conductor 410 can be filled into the second through-hole by electroplating. The conductor 410 is made of a metal with high thermal and electrical conductivity, such as copper, or a metal-resin mixture. The conductor 410 enables electrical connection of the circuit patterns of adjacent circuit boards.

[0080] The adhesive layer 500 has a thickness of 200μm and is made of PP.

[0081] This embodiment also provides a method for preparing a composite multilayer circuit board, including the following steps: S1. Take the silicon nitride ceramic circuit board after DPC metallization treatment, where the Ti / Cu seed layer thickness of the DPC metallization layer is 100nm / 1000nm, the electroplated copper layer thickness is 50μm, and positioning holes are reserved outside the stacking area. After alignment with the positioning holes, PP layer and PCB circuit board are stacked sequentially on the upper surface of DPC silicon nitride ceramic circuit board. The PP layer thickness is 200μm. Hot pressing is performed under the following conditions: 230℃, 60min. Using mechanical drilling, holes are drilled into the upper surface of the covered PCB circuit board and PP layer to form the second through hole. Then, the hole is filled by electroplating (the hole can be filled with metal or metal resin) to complete the electrical connection.

[0082] S2. After aligning with the positioning holes, stack the PP layer and another PCB on the upper surface of the PCB in sequence, and perform hot pressing. The hot pressing conditions are: 230℃, 60min. Use mechanical drilling to drill holes in the other PCB and PP layer to the upper surface of the PCB (i.e., form the second through hole). Then fill the hole with electroplating (the hole can be filled with metal or metal resin) to complete the electrical connection.

[0083] S3. Repeat step S2 until the PCB circuit board has 7 layers. Product fabrication is complete; the composite multilayer circuit board formed by the PCB circuit board and the DPC silicon nitride ceramic circuit board has a total of 8 layers.

[0084] Tests showed that the heat dissipation performance of the composite multilayer circuit board in this embodiment is 5% better than that of a PCB multilayer circuit board with the same number of layers. Example 4

[0085] This embodiment also provides a composite multilayer circuit board, such as Figure 7 and Figure 8 As shown, the composite multilayer circuit board includes eight layers of circuit boards stacked sequentially. The first and third layers are ceramic circuit boards 100; the second, fourth, to eighth layers are all organic circuit boards 200. Since the fourth to eighth layers are all of the same type of circuit board, therefore... Figure 7 and Figure 8 In the diagram, only the structure of a single organic circuit board 200 is shown for the 4th to 8th layers of the circuit board; an adhesive layer 500 is provided between adjacent circuit boards.

[0086] The ceramic circuit board 100 is a silicon nitride ceramic circuit board that has undergone DPC metallization treatment. The Ti / Cu seed layer thickness of the DPC metallization layer is 100nm / 1000nm, and the electroplated copper layer thickness is 50μm. Ceramic circuit board circuit patterns 110 are provided on both the upper and lower surfaces of the ceramic circuit board 100. A first through-hole is provided between the upper and lower surfaces, and a first metal pillar 120 is provided in the first through-hole to realize the electrical connection between the ceramic circuit board circuit patterns 110 on the upper and lower surfaces of the ceramic circuit board 100.

[0087] Organic circuit board 200 is a PCB circuit board. Organic circuit board circuit patterns 210 are provided on both the upper and lower surfaces of organic circuit board 200. A second through hole is provided between the upper and lower surfaces, and a second metal pillar 220 is provided in the second through hole to realize the electrical connection between the organic circuit board circuit patterns 210 on the upper and lower surfaces of this organic circuit board 200.

[0088] Second through-holes are provided in the adhesive layer 500 between the first and second circuit boards, and in the adhesive layer 500 between the third and eighth circuit boards. These second through-holes can be formed by mechanical drilling. A conductor 410 is disposed within each second through-hole. The conductor 410 can be filled into the second through-hole by electroplating. The conductor 410 is made of a metal with high thermal and electrical conductivity, such as copper, or a metal-resin mixture. The conductor 410 enables electrical connection between the circuit patterns of adjacent circuit boards.

[0089] A first through-hole is provided in the adhesive layer 500 between the second and third circuit boards. The first through-hole can be formed by laser processing. A solder connection layer 320 is provided in the first through-hole. The solder connection layer 320 is pre-formed on the circuit pattern on the upper surface of the second organic circuit board 200 by ball bonding. The solder connection layer 320 is spherical in shape with a diameter of 100μm and is made of tin-silver-copper alloy.

[0090] Metal connectors 310, specifically metal bosses, are provided on the circuit pattern on the lower surface of the third-layer ceramic circuit board 100. The metal bosses are made of copper and are formed using photolithography and electroplating processes. They have a height of 30μm to 80μm and are cylindrical in shape with a base diameter of 350μm. After polishing, the tolerance is less than ±10μm. The metal bosses are then welded to the solder connection layer 320 using vacuum reflow soldering to achieve electrical connection between the circuit patterns of the second-layer organic circuit board 200 and the third-layer ceramic circuit board 100.

[0091] The adhesive layer 500 has a thickness of 200μm and is made of PP.

[0092] This embodiment also provides a method for preparing a composite multilayer circuit board, including the following steps: S1. Take the silicon nitride ceramic circuit board after DPC metallization treatment, where the Ti / Cu seed layer thickness of the DPC metallization layer is 100nm / 1000nm, the electroplated copper layer thickness is 50μm, and positioning holes are reserved outside the stacking area. After alignment with the positioning holes, PP layer and PCB circuit board are stacked sequentially on the upper surface of DPC silicon nitride ceramic circuit board. The PP layer thickness is 200μm. Hot pressing is performed under the following conditions: 230℃, 60min. Using mechanical drilling, holes are drilled into the upper surface of the covered PCB circuit board and PP layer to form the second through hole. Then, the hole is filled by electroplating (the hole can be filled with metal or metal resin) to complete the electrical connection.

[0093] S2. Stack a PP layer with a thickness of 200μm on the upper surface of the PCB circuit board and perform hot pressing. The hot pressing conditions are: 230℃, 60min. Use mechanical drilling to drill holes in the covered PP layer to the metal circuit layer on the upper surface of the PCB circuit board (i.e., form the first through hole). Then, use a printed ball placement method to pre-fabricate tin-silver-copper solder at the hole position to form a solder connection layer with a diameter of 100μm.

[0094] S3. Take the silicon nitride ceramic circuit board after DPC metallization treatment. The thickness of the Ti / Cu seed layer of the DPC metallization layer is 100nm / 1000nm, and the thickness of the electroplated copper layer is 50μm. The metal bosses on the circuit pattern on the lower surface of the DPC silicon nitride ceramic circuit board are electroplated using photolithography and electroplating. The height of the metal bosses is 30μm to 80μm, and the shape of the metal bosses is cylindrical with a bottom diameter of 350μm. The metal bosses are polished to ensure that the error is less than ±10μm. The positioning marks on the DPC metallization layer are used for calibration. A pressure of 200MPa is applied, and the metal bosses are welded to the solder connection layer using vacuum reflow soldering. The welding vacuum is less than 10Pa. The temperature is gradually increased from room temperature to 300℃ at a heating rate of 1.0℃ / s and held at 300℃ for 10min. Then, it is naturally cooled to room temperature at a cooling rate of less than 1℃ / s to complete the soldering.

[0095] S4. After positioning and alignment, stack the PP layer and another PCB circuit board sequentially on the upper surface of the DPC silicon nitride ceramic circuit board, and perform hot pressing. The hot pressing conditions are: 230℃, 60min. Use mechanical drilling to drill holes in the other PCB circuit board and PP layer to the upper surface of the PCB circuit board (i.e., form the second through hole). Then, fill the hole with electroplating (the hole can be filled with metal or metal resin) to complete the electrical connection.

[0096] S5. After aligning with the positioning holes, stack the PP layer and the next PCB layer sequentially on the upper surface of the PCB circuit board, and perform hot pressing. The hot pressing conditions are: 230℃, 60min. Use mechanical drilling to drill holes in the covered PCB circuit board and PP layer to the upper surface of the PCB circuit board (i.e., form the second through hole). Then, fill the hole with electroplating (the hole can be filled with metal or metal resin) to complete the electrical connection.

[0097] S6. Repeat step S5 to complete the stacking of 3 more PCB circuit boards. The product fabrication is now complete, resulting in a composite multilayer circuit board with a total of 8 layers, formed by the PCB circuit board and the DPC silicon nitride ceramic circuit board.

[0098] Tests showed that the heat dissipation performance of the composite multilayer circuit board in this embodiment is 8% better than that of a PCB multilayer circuit board with the same number of layers. Example 5

[0099] This embodiment also provides a composite multilayer circuit board, such as Figure 9 and Figure 10As shown, the composite multilayer circuit board includes 16 layers of circuit boards stacked sequentially. The second layer is a ceramic circuit board 100; the first, third, and sixteenth layers are all organic circuit boards 200. Since the third to sixteenth layers are all of the same type of circuit board, therefore... Figure 9 and Figure 10 In the diagram, only the structure of a single organic circuit board 200 is shown for the 3rd to 16th layers of the circuit board; an adhesive layer 500 is provided between adjacent circuit boards.

[0100] The ceramic circuit board 100 is a silicon nitride ceramic circuit board that has undergone DPC metallization treatment. The Ti / Cu seed layer thickness of the DPC metallization layer is 100nm / 1000nm, and the electroplated copper layer thickness is 50μm. Ceramic circuit board circuit patterns 110 are provided on both the upper and lower surfaces of the ceramic circuit board 100. A first through-hole is provided between the upper and lower surfaces, and a first metal pillar 120 is provided in the first through-hole to realize the electrical connection between the ceramic circuit board circuit patterns 110 on the upper and lower surfaces of the ceramic circuit board 100.

[0101] Organic circuit board 200 is a PCB circuit board. Organic circuit board circuit patterns 210 are provided on both the upper and lower surfaces of organic circuit board 200. A second through hole is provided between the upper and lower surfaces, and a second metal pillar 220 is provided in the second through hole to realize the electrical connection between the organic circuit board circuit patterns 210 on the upper and lower surfaces of this organic circuit board 200.

[0102] Second through-holes are provided within the adhesive layer 500 between the second and sixteenth circuit boards. These second through-holes can be formed by mechanical drilling. Conductors 410 are installed within these second through-holes. The conductors 410 can be filled into the second through-holes by electroplating. The conductors 410 are made of a metal with high thermal and electrical conductivity, such as copper, or a metal-resin mixture. The conductors 410 enable electrical connections between the circuit patterns of adjacent circuit boards.

[0103] A first through-hole is provided in the adhesive layer 500 between the first and second circuit boards. The first through-hole can be formed by laser processing. A solder bonding layer 320 is provided in the first through-hole. The solder bonding layer 320 is pre-formed on the circuit pattern on the upper surface of the first organic circuit board 200 by ball bonding. The thickness of the solder bonding layer 320 is 50μm, and the material of the solder bonding layer 320 is tin-silver-copper alloy.

[0104] Metal connectors 310, specifically metal bosses, are provided on the circuit pattern on the lower surface of the second-layer ceramic circuit board 100. The metal bosses are made of copper and are formed using photolithography and electroplating processes. They have a height of 30μm to 80μm and are cylindrical in shape with a base diameter of 600μm. After polishing, the tolerance is less than ±10μm. The metal bosses are then welded to the solder connection layer 320 using vacuum reflow soldering to achieve electrical connection between the circuit patterns of the first-layer organic circuit board 200 and the second-layer ceramic circuit board 100.

[0105] The adhesive layer 500 has a thickness of 200μm and is made of PP.

[0106] This embodiment also provides a method for preparing a composite multilayer circuit board, including the following steps: S1. Take a PCB circuit board with a copper plating layer thickness of 35μm. After image exposure etching, complete the circuit pattern. Reserve positioning holes outside the stacking area. Align with the positioning holes and stack a PP layer on the upper surface of the PCB circuit board with a thickness of 200μm. Perform hot pressing at 230℃ for 60min. Use mechanical drilling to drill holes in the covered PP layer to the metal surface of the circuit pattern on the upper surface of the PCB circuit board (i.e., form the first through hole). Then, use ball bonding to complete the solder pre-fabrication to form a solder connection layer with a thickness of 50μm.

[0107] S2. Take the silicon nitride ceramic circuit board after DPC metallization treatment. The thickness of the Ti / Cu seed layer of the DPC metallization layer is 100nm / 1000nm, and the thickness of the electroplated copper layer is 50μm. The metal bosses on the circuit pattern on the lower surface of the DPC silicon nitride ceramic circuit board are electroplated using photolithography and electroplating. The height of the metal bosses is 30μm to 80μm, and the shape of the metal bosses is cylindrical with a bottom diameter of 600μm. The metal bosses are polished to ensure that the error is less than ±10μm. Using the positioning holes on the DPC metallization layer, the metal bosses are aligned with the positions on the PCB circuit board where the solder is pre-made. Apply a pressure of 500MPa and use vacuum reflow soldering. The soldering vacuum is less than 10Pa. The temperature is gradually increased from room temperature to 270℃ at a heating rate of 1.0℃ / s and held at 270℃ for 5min. Then, it is naturally cooled to room temperature at a cooling rate of less than 1℃ / s.

[0108] S3. On the upper surface of the DPC silicon nitride ceramic circuit board, after aligning with the positioning holes, stack the PP layer and another PCB circuit board in sequence, and perform hot pressing. The hot pressing conditions are: 230℃, 60min. Use mechanical drilling to drill holes in the other PCB circuit board and PP layer to the upper surface of the DPC silicon nitride ceramic circuit board (i.e., form the second through hole). Then fill the hole with electroplating (the hole can be filled with metal or metal resin) to complete the electrical connection.

[0109] S4. After aligning with the positioning holes, stack the PP layer and the next PCB layer sequentially on the upper surface of the PCB circuit board, and perform hot pressing. The hot pressing conditions are: 230℃, 60min. Use mechanical drilling to drill holes in the covered PCB circuit board and PP layer to the upper surface of the PCB circuit board (i.e., form the second through hole). Then, fill the hole with electroplating (the hole can be filled with metal or metal resin) to complete the electrical connection.

[0110] S5. Repeat step S4. Complete product preparation; the composite multilayer circuit board formed by PCB circuit board + DPC silicon nitride ceramic circuit board has a total of 16 layers.

[0111] Tests showed that the heat dissipation performance of the composite multilayer circuit board in this embodiment is 4% better than that of a PCB multilayer circuit board with the same number of layers.

[0112] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A composite multilayer circuit board, characterized in that, include: At least three layers of circuit boards are stacked together, and each layer of the circuit board is a single-layer structure; The circuit board is a ceramic circuit board or an organic circuit board, and the composite multilayer circuit board includes at least one layer of the ceramic circuit board and at least one layer of the organic circuit board. When a ceramic circuit board is located in the middle or top layer of the composite multilayer circuit board, the ceramic circuit board and its directly adjacent lower circuit board are electrically connected through a first electrical connection structure. The first electrical connection structure includes a metal connector and a solder connection layer. The metal connector is disposed on the ceramic circuit board, and the solder connection layer fixes the metal connector to the circuit pattern of the lower circuit board. The remaining directly adjacent circuit boards are electrically connected through a second electrical connection structure, which includes a conductor that penetrates the layers.

2. The composite multilayer circuit board according to claim 1, characterized in that, The metal connector is a metal boss.

3. The composite multilayer circuit board according to claim 2, characterized in that, The metal bosses are electroplated onto the circuit pattern of the ceramic circuit board.

4. The composite multilayer circuit board according to claim 2 or 3, characterized in that, The height of the metal boss is between 30μm and 80μm.

5. The composite multilayer circuit board according to claim 2 or 3, characterized in that, The metal boss is a cylinder, and the diameter of the bottom surface of the metal boss is between 100μm and 600μm.

6. The composite multilayer circuit board according to claim 2 or 3, characterized in that, The metal boss is disposed on the circuit pattern on the surface of the ceramic circuit board facing the lower circuit board, and the solder connection layer is disposed on the circuit pattern on the surface of the lower circuit board facing the ceramic circuit board, and the metal boss and the solder connection layer are disposed in a one-to-one correspondence.

7. The composite multilayer circuit board according to claim 6, characterized in that, The metal boss is made of copper; the solder bonding layer is made of at least one of gold, tin, copper, nickel and silver.

8. The composite multilayer circuit board according to claim 1, characterized in that, The thickness of the solder bonding layer is between 50 μm and 150 μm.

9. The composite multilayer circuit board according to claim 1, characterized in that, An adhesive layer is provided between adjacent circuit boards; the adhesive layer has a first through hole at the position corresponding to the first electrical connection structure, and the metal connector and the solder connection layer are disposed in the first through hole; the adhesive layer has a second through hole at the position corresponding to the second electrical connection structure, and the conductor is disposed in the second through hole.

10. The composite multilayer circuit board according to claim 1, characterized in that, The conductor is made of metal or a mixture of metal and resin.

11. A method for fabricating a composite multilayer circuit board, characterized in that, Includes the following steps: A circuit board with at least three single-layer structures is provided, wherein the circuit board is a ceramic circuit board or an organic circuit board, and the at least three-layer circuit board simultaneously includes at least one layer of the ceramic circuit board and at least one layer of the organic circuit board; The circuit boards are stacked one by one in a preset order, and the circuit boards are connected between every two adjacent layers. Wherein, when the stacking connection involves a ceramic circuit board located in the middle or top layer and its lower circuit board, a first connection method is used to connect them to form a first electrical connection structure. The first electrical connection structure includes a metal connector and a solder connection layer. The metal connector is disposed on the ceramic circuit board, and the solder connection layer fixes the metal connector to the circuit pattern of the lower circuit board. When the stacked connection involves other adjacent circuit boards, a second connection method is used to form a second electrical connection structure, which includes a conductor that penetrates between layers.

12. The preparation method according to claim 11, characterized in that, The metal connector is a metal boss.

13. The preparation method according to claim 12, characterized in that, The first connection method includes: Take a ceramic circuit board, and form the metal boss on the circuit pattern on one side of the ceramic circuit board through an electroplating process. The metal boss is electroplated and formed on the circuit pattern of the ceramic circuit board. Take a lower circuit board adjacent to the ceramic circuit board, provide an adhesive layer on the surface of the lower circuit board facing the ceramic circuit board, and process the adhesive layer to form a first through hole. The first through hole exposes the circuit pattern of the lower circuit board. Then, solder is pre-placed on the exposed circuit pattern to form a solder connection layer. The metal bosses are aligned one by one with the solder connection layer, and the electrical structural connection between the ceramic circuit board and the lower circuit board is completed through the welding step.

14. The preparation method according to claim 13, characterized in that, The solder pre-placement process is a ball-planting process, a printing process, or a spraying process; the processing process of the first through hole is laser cutting or machining.

15. The preparation method according to claim 13, characterized in that, The welding process employs vacuum hot-press welding or reflow welding, with a welding vacuum degree ≤10 Pascals. During the welding process, the temperature is raised from room temperature to 150℃~350℃ at a rate of 0.5℃ / s~4℃ / s, followed by holding at that temperature for 3min~10min.

16. The preparation method according to claim 13, characterized in that, The metal boss is made of copper; the solder bonding layer is made of at least one of gold, tin, copper, nickel and silver.

17. The preparation method according to claim 13, characterized in that, The height of the metal boss is between 30μm and 80μm; the metal boss is a cylinder, and the diameter of the bottom surface of the metal boss is between 100μm and 600μm.

18. The preparation method according to claim 13, characterized in that, The thickness of the solder bonding layer is between 50 μm and 150 μm.

19. The preparation method according to claim 11, characterized in that, The second connection method includes: An adhesive layer is placed between two adjacent circuit boards. After hot pressing, a second through hole is formed on the adhesive layer by laser drilling or mechanical drilling. The second through hole is filled with metal or a metal-resin mixture to form the conductor.

20. The preparation method according to claim 19, characterized in that, The conditions for the hot pressing step are: hot pressing temperature between 150℃ and 250℃, and holding time between 60min and 180min.

21. The preparation method according to claim 11, characterized in that, Before stacking layer by layer, the process also includes: drilling positioning holes or making alignment marks on the bottom circuit board as alignment references for subsequent stacking calibration and positioning steps.

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