Method and system for manufacturing printed circuit board with embedded cooling cavity and printed circuit board

Abstract

The present disclosure relates to a method for manufacturing a printed circuit board having an embedded cooling cavity. The method includes processing a portion of a soluble material to form a pattern; plating the pattern; filling the plating pattern with an electrically insulating material; and removing the remaining soluble material with a solvent to form a cooling cavity.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a method and system for manufacturing a printed circuit board with embedded cooling cavities and to a printed circuit board. BACKGROUND

[0002] Printed circuit boards (PCB) embedding windings inherently exhibit significant advantages such as low profile, ease of manufacturability, repeatability of electrical parameters and improved thermal performance.

[0003] They can be used for planar magnetic components, such as transformers and inductors. Nonetheless, planar magnetic components are systematically limited to a niche market in the low to medium power range. With the advent of wide bandgap devices (WBG) such as silicon carbide (SiC) or gallium nitride (GaN), current power converters are able to operate at much higher switching frequencies than traditional silicon-based devices. The limitation on magnetic elements is thus alleviated, opening the way for PCB-based planar magnetic technology to develop towards higher power classes.

[0004] Due to their systematic use in high-density systems, efficient thermal management is a challenging task. In high power applications, liquid cooling is mainly used. However, traditional cold plates can only cool from the outside of the device, i.e. the magnetic material. This leads to poor heat extraction from the core of the system, i.e. the copper winding, which becomes a limiting factor in the design. Indeed, further increase in power density would mean increasing the current density, leading to higher losses with a limited cooling area. For alleviation purposes, it is usually recommended to connect the winding to the cold plate through a copper block insulated with a thermal interface material.

[0005] The aim of the present disclosure is to cool the PCB winding from its vicinity to reduce hot spots as much as possible. On the other hand, the cooling system should be chosen to avoid increasing excessive losses that can arise due to the positioning of metallic pieces in the vicinity of AC magnetic fields (eddy currents). Finally, the electrical insulation of the cooling device is a key point for personnel safety. From a manufacturing point of view, the advantage of PCB-based windings is the cost-effectiveness and high repeatability of the dimensions.

[0006] LIST OF CITATIONS

[0007] PATENT LITERATURE

[0008] U.S. Patent No. 7289329 SUMMARY

[0009] The present disclosure aims at providing a method and system that provides an efficient cooling system for windings intended to be used in magnetic components.

[0010] To this end, the present disclosure relates to a method for manufacturing a printed circuit board with embedded cooling cavities, the method comprising:

[0011] - Process a portion of the soluble material to form a pattern;

[0012] - The pattern is plated;

[0013] - The pattern is filled with an electrically insulating material; and

[0014] - Use a solvent to remove the remaining soluble material to form a cooling chamber.

[0015] This disclosure also relates to a system for manufacturing printed circuit boards with embedded cooling cavities, the system being configured to:

[0016] - Command to process a portion of the soluble material to form a pattern;

[0017] - Command to coat the pattern;

[0018] - The pattern is to be filled with electrical insulating material; and

[0019] - The command uses a solvent to remove the remaining soluble material to form a cooling chamber.

[0020] Therefore, plated patterns can be used as thermal management systems, in which fluids or gases flow within to cool the printed circuit board. Since the cooling system is embedded in the PCB, thermal management is significantly improved compared to conventional techniques due to the reduced number of thermal interfaces. Plated patterns can also be used to carry current. In this case, since the potential of the pattern is applied to the coolant, the coolant must be carefully selected based on its dielectric properties. Because this device is capable of carrying current, it can be advantageously used in magnetic components such as inductors or transformers.

[0021] Depending on the specific characteristics, the method may also include, prior to removing the remaining soluble material with a solvent:

[0022] -Process another portion of the soluble material to form another pattern;

[0023] - Plating the other pattern; and

[0024] - Fill another plating pattern with conductive material.

[0025] Therefore, the electrically formed patterns filled with conductive material used to carry current and cool components are no longer in contact. Since the electrically insulating material between the patterns ensures insulation, there is no need to pay special attention to the dielectric properties of the coolant or the risk of ionization. In the case of using conductive fluids, the hydraulic circuit does not need to be electrically insulated. Current-carrying capacity remains possible.

[0026] Depending on specific characteristics, the method also includes:

[0027] - A substrate comprising at least the electrically insulating material; and

[0028] - Insert the laminated substrate into the magnetic component.

[0029] Therefore, the resulting circuit board can be used not only for cooling purposes, but also as a set of windings to carry current and thus magnetize magnetic components.

[0030] Depending on the specific features, the method further includes performing at least one of chemical etching and drilling on the laminate to form an electrical connection before inserting the laminate substrate into the magnetic component.

[0031] Based on specific characteristics, the obtained printed circuit board is inserted between the conductors of the primary winding and the conductors of the secondary winding of the transformer.

[0032] Therefore, the cooling system is located in the middle of the transformer and prevents hot spots that would normally be located in that area.

[0033] Based on specific characteristics, the two obtained printed circuit boards are located at the top of the conductor of the primary winding and the bottom of the conductor of the secondary winding of the transformer.

[0034] Therefore, the cooling system can cool the conductors of the primary winding with the core portion on the top side and the conductors of the secondary winding with the core portion on the bottom side. Furthermore, due to its location in the near-zero field region, this arrangement helps reduce eddy current losses in the resulting printed circuit board.

[0035] Based on specific characteristics, two obtained printed circuit boards are stacked, each of which is inserted into a magnetic component. One obtained printed circuit board acts as the primary winding of a transformer, and the other obtained printed circuit board acts as the secondary winding of a transformer.

[0036] Therefore, thermal extraction is performed directly inside the winding to obtain the best results.

[0037] This disclosure also relates to a printed circuit board, the printed circuit board comprising:

[0038] - An embedded cooling cavity, at least a portion of which is surrounded by a coating. Attached Figure Description

[0039] The features of this disclosure will become clearer from the following description of exemplary embodiments, which is made with reference to the accompanying drawings, in which:

[0040] Figure 1a This represents a first example of the algorithm for a printed circuit board with an embedded cooling cavity according to the present disclosure, which can be used in magnetic components;

[0041] Figure 1aThis is a second example of the process for a printed circuit board with an embedded cooling cavity according to the present disclosure, which can be used in magnetic components;

[0042] Figure 2 An example of the architecture of an apparatus for manufacturing a printed circuit board with an embedded cooling cavity according to the present disclosure, which can be used in magnetic components;

[0043] Figure 3 This illustrates an example of a printed circuit board with an embedded cooling cavity according to the present disclosure;

[0044] Figures 4a to 4h Examples of different steps for manufacturing a printed circuit board with an embedded cooling cavity according to this disclosure;

[0045] Figures 5a to 5h Examples of different steps for manufacturing a printed circuit board with an embedded cooling cavity according to this disclosure;

[0046] Figures 6a to 6f Examples of different steps for manufacturing a printed circuit board with an embedded cooling cavity according to this disclosure;

[0047] Figure 7 This illustrates an example of a magnetic component comprising a printed circuit board with an embedded cooling cavity according to the present disclosure;

[0048] Figure 8 This indicates an example of a magnetic component including a printed circuit board with an embedded cooling cavity according to the present disclosure; and

[0049] Figure 9 This illustrates an example of a magnetic component that includes a printed circuit board with an embedded cooling cavity according to the present disclosure. Detailed Implementation

[0050] Figure 1a This represents a first example of a process for a printed circuit board with an embedded cooling cavity according to this disclosure, which can be used in magnetic components. For example... Figure 1a As shown, this process includes steps S100 to S105.

[0051] This process will be referenced below. Figure 2 The disclosed apparatus 20 for manufacturing a printed circuit board with an embedded cooling cavity according to the present disclosure is used in magnetic components.

[0052] Device 20 can constitute a system for manufacturing printed circuit boards with embedded cooling cavities.

[0053] This disclosure utilizes subtractive manufacturing techniques applied to PCB technology. To achieve this, conventional prepreg materials are partially replaced by special soluble prepreg materials that have a liquid or solvent. Conventional prepreg materials are insoluble materials. In other words, conventional insoluble prepreg materials are insoluble in liquids or solvents that can dissolve soluble prepreg materials. Soluble prepreg materials are, for example, polyvinyl alcohol, butyryne glycol-vinyl alcohol copolymers, or inorganic salts in compressed form. The solvent can be water.

[0054] PCB PP (prepreg) or Pre-preg is short for Pre-Impregated, also known as Preg, and consists of a glass fiber fabric impregnated with resin. The resin is partially cured but not hardened during the prepreg coating process. When the PCB is heated during the pressing process, the resin in the prepreg flows, adheres, and bonds the PCB core to the copper foil or other materials.

[0055] Figure 4a An example of a component with an embedded cooling cavity is given in the document.

[0056] exist Figure 4a In this substrate, the substrate is composed of a soluble prepreg material 400 and two copper layers 401 and 402.

[0057] Specifically, the soluble prepreg material 400 has, for example, a plate shape, and two copper layers 401 and 402 are disposed on both sides of the soluble prepreg material 400. In other words, the copper layer 401, the soluble prepreg material 400, and the copper layer 402 are arranged in the thickness direction of the soluble prepreg material 400. The thickness direction is equal to... Figures 4a to 4h The up and down directions.

[0058] In step S100, the device 20 commands the realization of the electrical pattern of the magnetic component embedded in the cooling cavity.

[0059] In other words, device 20 commands a portion of the soluble prepreg material 400 to be processed to form a pattern, or device 20 may command processing equipment (e.g., a milling machine or a drilling machine) to process a portion of the soluble prepreg material 400 to form a pattern. Systems for manufacturing printed circuit boards with embedded cooling cavities may include processing equipment.

[0060] The substrate is essentially drilled or milled to form mechanical vias (i.e., holes or slits) or micro-holes or patterns, depending on the thickness of the substrate.

[0061] Figure 4b An example is given in the document.

[0062] exist Figure 4b In this process, openings 410a to 410g are realized in a substrate consisting of a soluble prepreg material 400 and two copper layers 401 and 402.

[0063] The openings 410a to 410g penetrate the substrate in the thickness direction.

[0064] The pattern is formed by openings 410a to 410g and the remaining soluble prepreg material 400.

[0065] In step S101, the device 20 commands, for example, copper plating to coat the openings 410a to 410g.

[0066] In other words, device 20 commands the plating pattern, or device 20 can command the plating equipment to plating the pattern. The plating equipment may include, for example, a plating tank. Systems for manufacturing printed circuit boards with embedded cooling cavities may include plating equipment.

[0067] Figure 4c An example is given, which shows a copper plating 420 with an opening.

[0068] The plating layer 420 is formed on the inner surface of the opening. In other words, the plating layer 420 is formed on the side surface of the remaining soluble prepreg material 400 facing the opening. At this time, plating layers can be formed on the top surface of the copper layer 401 and the lower surface of the copper layer 402.

[0069] In step S102, the device 20 commands the opening to be filled with an electrically insulating material (e.g., resin). The resin may be, for example, TAIYO THP-100 DX1 from TAIYOAMERICA™ or resin supplied by Micromax™ CB100.

[0070] In other words, device 20 commands the plating pattern to be filled with an electrically insulating material, or device 20 can command a filling device to fill the plating pattern with an electrically insulating material. The filling device can be, for example, a coating machine, a syringe, a dispenser, etc. Systems for manufacturing printed circuit boards with embedded cooling cavities may include filling devices.

[0071] Figure 4d An example is given, which shows fillers 430a to 430g with openings filled by resin.

[0072] The resin (i.e., the electrical insulating material) is insoluble in solvents that can dissolve the soluble prepreg 400.

[0073] In step S103, the substrate obtained in step S102 is laminated to obtain, as shown in step S102. Figure 4e The PCB shown.

[0074] The substrate obtained in step S102 includes at least filler 430a to 430g (i.e., electrical insulating material).

[0075] Figure 4eThe substrate obtained in step S102 is shown, on which a conventional prepreg layer 441 and a copper layer 440 are laminated on top, and on which a conventional prepreg layer 442 and a copper layer 443 are laminated on bottom.

[0076] In other words, the copper layer 440, the prepreg material 441, the substrate, the prepreg material 442, and the copper layer 443 are arranged in the thickness direction.

[0077] In step S104, the copper layer is respectively passed through Figure 4f The vias 450 and 451 shown are electrically connected to the plating layer created in step S101, and the copper layer is chemically etched or drilled to form a layer composed of... Figure 4g The inductor component is composed of conductive patterns 460a to 460l shown.

[0078] In other words, at least one of chemical etching and drilling is performed on the laminates (i.e., copper layers 440 and 443 and prepreg materials 441 and 442) to make electrical connections via vias 450 and 451.

[0079] In step S105, a solvent is used to remove the soluble prepreg.

[0080] In other words, device 20 can command the removal of remaining soluble prepreg material with a solvent to form a cooling cavity, or device 20 can command the removal equipment to remove remaining soluble prepreg material with a solvent to form a cooling cavity. The removal equipment may include, for example, an syringe capable of supplying solvent. Systems for manufacturing printed circuit boards with embedded cooling cavities may include the removal equipment.

[0081] result, Figure 4h The plated openings 470a to 470f and conductive patterns 460a to 460l shown form an inductor.

[0082] Openings 470a to 470f correspond to cooling chambers. A portion of each of the openings 470a to 470f is surrounded by a coating made in step S101.

[0083] In other words, the printed circuit board includes an embedded cooling cavity, and at least a portion of the cooling cavity is surrounded by a plating layer.

[0084] Figure 1b This is a second example illustrating the process of a printed circuit board with an embedded cooling cavity according to this disclosure, which can be used in magnetic components. For example... Figure 1b As shown, this process includes steps S120 to S126.

[0085] This process will be referenced below. Figure 2The disclosed apparatus 20 for manufacturing a printed circuit board with an embedded cooling cavity according to the present disclosure is used, the printed circuit board being used in a magnetic component.

[0086] The apparatus 20 of the second example of this process can perform functions similar to those of the first example described above.

[0087] This disclosure utilizes subtractive manufacturing techniques applied to PCB technology. To achieve this, conventional prepreg materials are partially replaced with special soluble prepreg materials containing liquids or solvents.

[0088] Preferably, the soluble material is soluble in a cooling liquid material that will be at least partially used during cooling. For example, the cooling liquid material is water. For example, the soluble material is polyvinyl alcohol (PVA), which can withstand lamination temperatures. For example, the soluble material is a butynediol-vinyl alcohol copolymer. For example, the soluble material is an inorganic salt, such as compressed NaCl.

[0089] PCB PP (prepreg) or Pre-preg is short for Pre-Impregated, also known as Preg, and consists of a glass fiber fabric impregnated with resin. The resin is partially cured but not hardened during the prepreg coating process. When the PCB is heated in the pressing process, the resin in the prepreg flows, adheres, and bonds the PCB core to the copper foil or other materials.

[0090] Figure 5a An example is given in the document.

[0091] exist Figure 5a In the substrate, the substrate consists of a soluble prepreg material 500 and two copper layers 501 and 502.

[0092] In step S120, the device 20 commands the realization of the electrical pattern of the magnetic component embedded in the cooling cavity.

[0093] Depending on the thickness of the substrate, the substrate is basically drilled or milled using mechanical vias (i.e., holes or slits) or micro-holes or patterns.

[0094] Figure 5b An example is given in the document.

[0095] exist Figure 5b In this process, openings 510a to 510d are implemented in a substrate consisting of a soluble prepreg material 500 and two copper layers 501 and 502.

[0096] Figure 6a Another example is given in the text.

[0097] exist Figure 6a In this process, conventional prepreg material 600 is partially replaced by a special soluble prepreg material 601.

[0098] The soluble prepreg material 601 is milled to form three cavities 602.

[0099] In other words, the soluble prepreg material 601 is milled to form the winding cavity 602.

[0100] The substrate is designed to be placed in the magnetic core 603.

[0101] In step S121, the device 20 commands, for example, copper plating of the openings 510a to 510d or milling of the pattern 602.

[0102] Figure 5c An example is given, which shows a copper plating 520 with an opening.

[0103] In step S122, device 20 commands the opening to be filled with a conductive material (e.g., copper). Figure 5d An example is given, which shows openings 530a to 530c filled with copper.

[0104] Figure 6b Another example is given, which shows filler 612 that is copper-plated and filled with copper.

[0105] Copper filler can be applied using plating equipment, coating machines, syringes, dispensers, etc.

[0106] In step S123, the device 20 commands at least one of drilling and milling the substrate.

[0107] Depending on the thickness of the substrate, the substrate is basically drilled or milled using mechanical vias (i.e., holes or slits) or micro-holes or patterns.

[0108] exist Figure 5e An example is given in the document.

[0109] exist Figure 5e In this process, openings 540a to 540c are realized in a substrate consisting of a soluble prepreg material 500 and two copper layers 501 and 502.

[0110] Figure 6c Another example is given in which a soluble prepreg material is milled to form a separated filled winding (i.e., filler 612, see [reference]). Figure 6b ) cavity 630.

[0111] In the same step, cavity 630 is chemically plated to form a shape such as Figure 6d The chemical plating cavity 640 is shown.

[0112] In step S125, the device 20 commands the opening created in step S123 to be filled with an electrically insulating material (e.g., resin).Figure 5f An example is given, which shows fillers 550a to 550c with openings filled by resin.

[0113] Figure 6e Another example is given, which shows a filler 651 through the openings in the resin.

[0114] In step S126, a solvent is used to remove the soluble prepreg.

[0115] Figure 6f An example is given in the document.

[0116] As a result, the plated openings, plated vias, and copper-filled vias form a conductive pattern that includes cooling channels formed by cavities exposed by the removed soluble prepreg, and these cooling channels also serve as conductive patterns.

[0117] Based on specific characteristics, perform the following steps:

[0118] - The substrate obtained by lamination achieves, for example, Figure 5g The PCB shown

[0119] - Electrically connect the copper layer to the vias 570 and 571 respectively. Figure 5h The plating layer formed at step 121 is shown, and the copper layer is chemically etched or drilled to form an inductor component consisting of a conductive pattern.

[0120] Figure 5g The PCB obtained in step S126 is shown, on which a conventional prepreg layer 561 and a copper layer 560 are laminated on top, and a conventional prepreg layer 562 and a copper layer 563 are laminated on the bottom.

[0121] Figure 2 An example of the architecture of an apparatus for manufacturing a printed circuit board with an embedded cooling cavity according to the present disclosure is shown, which can be used in magnetic components.

[0122] The apparatus 20 for manufacturing a printed circuit board with an embedded cooling cavity according to the present disclosure, which can be used in magnetic components, has, for example, components connected together via a bus 201 and... Figure 1a or Figure 1b The architecture of the program-controlled processor 200 is disclosed.

[0123] Bus 201 links processor 200 to read-only memory (ROM) 242, random access memory (RAM) 203 and input / output interface (I / OI / F) 205.

[0124] Memory 203 contains registers designed to receive variables and... Figure 1aOr instructions for procedures related to the processes disclosed in 1b.

[0125] Read-only memory or possibly flash memory 242 contains with Figure 1a The instructions of the program related to the process disclosed in 1b are loaded into the random access memory 203 when the device 20 is powered on. Alternatively, the program can also be executed directly from the ROM 242.

[0126] The control performed by device 20 can be implemented in software by executing an instruction set or program by a programmable computing machine (such as a PC (personal computer), DSP (digital signal processor), or microcontroller); or in hardware by a machine or special-purpose component (such as a FPGA (field programmable gate array) or ASIC (application-specific integrated circuit).

[0127] In other words, device 20 includes circuitry or means including circuitry, such that device 20 performs the same actions as... Figure 1a or Figure 1b The procedures related to the publicly disclosed process.

[0128] In other words, the device 20 may include at least a memory (e.g., RAM 203) in which a program is loaded and a processor 200 that can execute the program to perform the functions described above.

[0129] Figure 3 This illustrates an example of a printed circuit board with an embedded cooling cavity according to the present disclosure.

[0130] exist Figure 3 In this example, conventional prepreg material 31 is partially replaced by soluble prepreg material 32. Both the conventional and soluble prepreg materials are milled to provide channels 33, which are plated with a conductive material such as copper to provide a conductive pattern. After dissolving the soluble prepreg, liquid or gas is injected into the channels formed by the dissolved soluble prepreg to provide a cooling chamber.

[0131] Figure 7 This illustrates an example of a magnetic component that includes a printed circuit board with an embedded cooling cavity according to the present disclosure.

[0132] exist Figure 7 In the example, the printed circuit board embedded with the cooling cavity 701 serves only as a cooler, located at the closest point between the primary winding conductor 700 and the secondary winding conductor 702, and more precisely between the primary and secondary windings. The cooling cavity does not carry any magnetic device current. However, since the cooling cavity is made wholly or partially of a conductive material, eddy currents are generated within it due to the presence of a near-magnetic field generated by the magnetic device. The density of vias can also be adjusted to control the pressure drop of the pumping device and tailor effective cooling.

[0133] Since the printed circuit board with the embedded cooling cavity 701 serves as a cooler, it is not necessary to provide it therein. Figure 4e The copper layers 440 and 443 shown, and the prepreg materials 441 and 442, or Figure 5g The copper layers 560 and 563 and the prepreg materials 561 and 562 are shown.

[0134] Figure 8 This illustrates an example of a magnetic component that includes a printed circuit board with an embedded cooling cavity according to the present disclosure.

[0135] exist Figure 8 In the example, the printed circuit board embedded with cooling cavities 800 and 803 serves only as a cooler, located at the closest point to conductor 801 of the primary winding and conductor 802 of the secondary winding, and more precisely at the top of primary winding 801 and the bottom of secondary winding 803. The cooling cavities do not carry any magnetic current. However, since the cooling cavities are made wholly or partially of conductive material, eddy currents are generated within them due to the presence of a near-magnetic field generated by the magnetic device. The density of vias can also be adjusted to control the pressure drop of the pumping device and customize effective cooling.

[0136] Since the printed circuit board with embedded cooling chambers 800 and 803 serves as the cooler, it is not necessary to provide [something] within it. Figure 4e The copper layers 440 and 443 shown, and the prepreg materials 441 and 442, or Figure 5g The copper layers 560 and 563 and the prepreg materials 561 and 562 are shown.

[0137] Figure 9 This illustrates an example of a magnetic component that includes a printed circuit board with an embedded cooling cavity according to the present disclosure.

[0138] exist Figure 9 In the example, the printed circuit boards embedded with cooling cavities 900 and 901 are used as the primary winding and secondary winding, respectively.

[0139] Of course, many modifications can be made to the embodiments described above within the scope of this disclosure.

[0140] In the above embodiments, soluble prepreg materials 400, 500, and 601 are used, but this disclosure is not limited thereto. Soluble materials such as polyvinyl alcohol (PVA), butynediol-vinyl alcohol copolymer, or inorganic salts (e.g., compressed NaCl) can be used instead of soluble prepreg materials 400, 500, or 601. The soluble materials may not include glass fiber fabrics.

Claims

1. A method for manufacturing a printed circuit board having an embedded cooling cavity, the method comprising: - Process a portion of the soluble material to form a pattern; - The pattern is plated; - Fill the plated pattern with electrical insulating material; as well as - Use a solvent to remove the remaining soluble material to form a cooling chamber.

2. The method according to claim 1, wherein, The method further includes, before removing the remaining soluble material with the solvent: -Process another portion of the soluble material to form another pattern; - Plating the other pattern; and - Fill another plating pattern with conductive material.

3. The method according to claim 1 or 2, wherein, The method further includes: - A substrate comprising at least the electrically insulating material; and - Insert the laminated substrate into the magnetic component.

4. The method according to claim 3, wherein, The method further includes performing at least one of chemical etching and drilling on the laminate to form an electrical connection before inserting the laminate substrate into the magnetic component.

5. The method according to any one of claims 1 to 4, wherein, The obtained printed circuit board is inserted between the conductors of the primary winding and the conductors of the secondary winding of the transformer.

6. The method according to any one of claims 1 to 4, wherein, Position the two obtained printed circuit boards at the top of the conductors of the primary winding and the bottom of the conductors of the secondary winding of the transformer.

7. The method according to any one of claims 1 to 4, wherein, Two obtained printed circuit boards are stacked, and each printed circuit board is inserted into a magnetic component. One obtained printed circuit board acts as the primary winding of the transformer, and the other obtained printed circuit board acts as the secondary winding of the transformer.

8. A system for manufacturing a printed circuit board with an embedded cooling cavity, the system being configured to: - Command to process a portion of the soluble material to form a pattern; - Command to coat the pattern; - The pattern is to be filled with electrical insulating material; and - The command uses a solvent to remove the remaining soluble material to form a cooling chamber.

9. A printed circuit board, the printed circuit board comprising: - An embedded cooling cavity, at least a portion of which is surrounded by a coating.

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