Metal foil-coated substrate embedded with power chip

Abstract

The invention provides a metal foil-coated substrate embedded with a power chip, which belongs to the technical field of power electronics and comprises a metal foil, an insulating material, the power chip, a metal connecting column and a double-sided metal foil-coated insulating substrate, the manufacturing method of the substrate comprises the following steps: welding or sintering the power chip on the metal foil at the lower layer; the metal connecting column is welded or sintered on the power chip or the metal foil on the lower layer; a layer of metal foil is welded or sintered above the metal connecting column; and an insulating material is filled between the two layers of metal plates. According to the invention, the insulating substrate and the power chip are sintered on the metal foil plate at the bottom layer, and then the metal connecting column is connected between the metal foil plates through the columnar metal object instead of the drilling and electroplating connection mode of a printed circuit board (PCB). Therefore, the connection reliability of the metal columns is ensured, and drilling and electroplating processes are not needed in the subsequent production process of the printed circuit board. And the production efficiency and quality are greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to a metal foil-clad substrate with embedded power chips. Background Art

[0002] The growing demand for high-efficiency, high-power density modules in new energy vehicles, industrial automation and other fields has promoted the development of power modules. The current power modules all use traditional frame packaging. The noise of these packages is relatively large and has reached its upper limit. There is relatively little room for improvement. PCB embedded power modules have many advantages. The package noise can be made very low, which means that the loss is also greatly reduced. Embedding power chips in PCBs was initiated by Europe and is currently in the stage of technical verification and development. It has not yet been widely used in terminal products.

[0003] The metal foil clad board with embedded power chip is the core board for manufacturing PCB embedded power module.

[0004] Limitations of traditional packaging: Traditional power module packaging forms such as frame modules and injection-molded modules use copper-clad ceramic substrates with high thermal conductivity and electrical insulation as carriers of power chips. These packages can only complete circuit connections through single-layer wiring, supplemented by overhead bonding wires, which limits electrical performance and heat dissipation.

[0005] Technical advantages of PCB embedded power chip: PCB embedded power module utilizes the multi-layer wiring capability of PCB, reduces EMC impact by controlling line spacing and layer spacing, the insulation material meets high-voltage insulation requirements, and the electronic devices embedded in the PCB can achieve excellent heat dissipation performance through high heat dissipation materials and reasonable heat dissipation layer design.

[0006] Performance potential: Compared with traditional packaging forms, PCB embedded power modules have significant advantages in unit power cost, power density, product delivery and iteration speed, and are expected to far surpass traditional packaging technology.

[0007] Application of wide bandgap devices: The new generation of wide bandgap semiconductor devices represented by gallium nitride and silicon carbide have shown performance far superior to that of silicon devices, playing a very important role in significantly improving the power density of converters. PCB embedded power module technology can give full play to the high-frequency performance of wide bandgap devices and promote their high-frequency applications.

[0008] Technical challenges: The high-frequency application of wide-bandgap devices makes them more sensitive to parasitic parameters. Reducing the parasitic parameters of the package is an important guarantee for promoting the high-frequency application of wide-bandgap devices.

[0009] In the existing PCB production process for embedded power chips, laser drilling and electroplating holes are used to connect power chips. The volume of semiconductor (silicon carbide, gallium nitride) power chips is relatively small. A PCB of 150cmx75cm requires 20 to 30 power chips, and the total number of holes drilled reaches more than 10,800 holes of 100um, which places high demands on the positioning accuracy of drilling holes. These holes also reduce the mechanical strength of the PCB.

[0010] The information about the power chip disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be considered as an admission or any form of implication that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0011] The object of the present invention is to provide a metal foil-clad substrate with embedded power chip.

[0012] To achieve the above object, the present invention provides the following solutions:

[0013] A metal foil-clad substrate with embedded power chip, comprising:

[0014] Metal foil, insulating material, power chip and metal connecting column;

[0015] The method for making the substrate includes:

[0016] Soldering or sintering the metal connection column to the power chip or the underlying metal foil;

[0017] A layer of metal foil is welded or sintered on the metal connecting column;

[0018] Fill the insulation material between the two metal sheets.

[0019] Optionally, the manufacturing method specifically includes:

[0020] Printing sintered silver / copper paste on the bottom copper plate using a printing device;

[0021] Use the chip placement equipment to attach the bare power chip and some metal connection pillars to the sintered silver / copper paste;

[0022] Use sintering equipment to sinter the power chip and some metal connection columns to the bottom copper plate at 20Mpa pressure, 260℃, and 5 minutes;

[0023] Use a glue coating machine to apply sintered silver / copper paste on the upper end of the power chip;

[0024] Attach the remaining metal connection pillars to the silver / copper paste on the top of the power chip;

[0025] Use sintering equipment to sinter the metal connection column onto the power chip at 20Mpa pressure, 260°C, and 5 minutes;

[0026] Use a glue coating machine to apply sintered silver / copper paste on the top of all sintered metal connecting columns;

[0027] Use a placement machine to attach the top copper plate to the metal connection posts;

[0028] Use a sintering device to sinter the top copper plate onto the metal connecting column at 20 MPa pressure, 260 degrees Celsius, and 5 minutes;

[0029] The Epoxy Mold Compound epoxy resin molding material is injected between two metal plates at 150°C and 50 tons of mold pressure using an injection molding machine; all power chips and metal connecting columns between the top and bottom layers are completely contained in the EMC, and the embedded power chip clad metal foil substrate is completed.

[0030] Optionally, the substrate further comprises a double-sided metal foil-covered insulating substrate; the manufacturing method of the substrate comprises:

[0031] Solder or sinter the insulating substrate and the power chip to the underlying metal foil;

[0032] Soldering or sintering the connection metal pillars to the copper foil of the power chip and the insulating substrate;

[0033] Lay the top metal foil sheet on the connecting metal pillars and weld or sinter them together;

[0034] The insulating material is filled and solidified between two layers of metal foil plates by injection molding, surrounding the power chip and the insulating substrate.

[0035] Optionally, metal pillars or metal sheets in shapes not limited to circular, rectangular, elliptical, or square, and metal connecting pillars with thin lower ends and thick upper ends are welded or sintered above the power chip and the copper foil. The number of metal connecting pillars or metal sheets in any area on the power chip and the copper foil area may be multiple or single.

[0036] Optionally, a temperature sensor is further arranged between the two metal plates.

[0037] Optionally, a metal base is provided below the power chip, and the shape of the base includes but is not limited to L-shaped, U-shaped, circular, and square. Each base has a raised platform for welding or sintering to the upper metal foil, and a recessed portion for burying the power chip in the base. Finally, after the power chip is sintered or welded to the recessed portion of the base, the top of the power chip and the raised portion of the base remain flat as a whole.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention provides a metal foil-clad substrate embedded with a power chip. During the manufacturing process, a metal connection column or a metal connection sheet is first welded or sintered to the power chip or the lower metal foil; then a layer of metal foil is welded or sintered above the metal connection column or the metal connection sheet; and finally, the insulating material is filled between the two metal plates by injection molding. The present invention sinters the insulating substrate and the power chip to the bottom metal foil plate, and then replaces the printed circuit board (PCB) drilling and electroplating connection method by connecting the metal connection column or the metal connection sheet with a columnar or sheet-shaped metal object between the metal foil plates. The reliability of such a metal columnar connection is guaranteed, and the subsequent printed circuit board production process does not require drilling and electroplating processes. The production efficiency and quality are greatly improved.

[0040] The present invention adopts sintered metal connection columns or direct sintering to achieve the connection achieved by traditional laser drilling and electroplating. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0042] Figure 1 This is a schematic diagram of the substrate structure provided in Example 1 of the present invention.

[0043] Figure 2 This is an enlarged view of the internal structure of the substrate provided in Example 1 of the present invention.

[0044] Figure 3 This is a side schematic diagram of the substrate structure provided in Example 1 of the present invention.

[0045] Figure 4 This is a schematic structural diagram of a substrate provided with a temperature sensor provided in Example 1 of the present invention.

[0046] Figure 5 This is a schematic diagram of the substrate structure provided in Example 2 of the present invention.

[0047] Figure 6 This is a schematic diagram of the substrate structure provided in Example 3 of the present invention.

[0048] Figure 7 This is a schematic diagram of the substrate structure provided in Example 4 of the present invention.

[0049] Figure 8 This is a schematic diagram of the substrate structure provided in Example 5 of the present invention.

[0050] Fig. 9 This is a diagram of the shape of the metal base provided by the present invention. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] The traditional PCB manufacturers embed power chips into substrates and then make PCBs as follows:

[0053] Slot the prepreg and put the power chip into the slot;

[0054] Place copper foil on the upper and lower layers;

[0055] Press them together;

[0056] drilling;

[0057] plating;

[0058] Etching to make circuit patterns;

[0059] The object of the present invention is to provide a metal foil-clad substrate for embedded power chips capable of improving production efficiency and quality.

[0060] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0061] Embodiment 1:

[0062] This embodiment provides a metal foil substrate with embedded power chip, such as Figure 1-3 Shown are: metal foil, insulating material, power chip and metal connecting pillars.

[0063] The method for manufacturing the substrate includes:

[0064] Sintering the power chip onto a double-sided copper-clad insulating substrate

[0065] Soldering or sintering the metal connection column to the power chip or the underlying metal foil;

[0066] A layer of metal foil is welded or sintered on the metal connecting column;

[0067] The insulation material is filled between the two metal plates by injection molding. From then on, the entire embedded power chip substrate is produced. The standard PCB production process is used for the rest of the production.

[0068] Etching to create circuit patterns.

[0069] The specific production method is:

[0070] Printing sintered silver / copper paste on the bottom copper plate using a printing device;

[0071] Use the chip placement equipment to attach the bare power chip and some copper pillars to the sintered silver / copper paste;

[0072] Use sintering equipment to sinter the power chip and some metal connection columns to the bottom copper plate at 15Mpa pressure, 260°C, and 5 minutes;

[0073] Use a glue coating machine to apply sintered silver / copper paste on the upper end of the power chip;

[0074] Attach the remaining metal connection pillars to the silver / copper paste on the top of the power chip;

[0075] Use sintering equipment to sinter the metal connection column onto the power chip at 20Mpa pressure, 260°C, and 5 minutes;

[0076] Use a glue coating machine to apply sintered silver / copper paste on the top of all sintered copper connection pillars;

[0077] Use a placement machine to attach the top copper plate to the metal connection posts;

[0078] Use a sintering device to sinter the top copper plate onto the metal connecting column at 20 MPa pressure, 260 degrees Celsius, and 5 minutes;

[0079] An injection molding machine is used to inject EMC (Epoxy Mold Compound) epoxy resin molding material between two metal plates at 150°C and 50 tons of mold pressure; all power chips and metal connecting columns between the top and bottom layers are completely contained in the EMC, and the embedded power chip metal foil substrate is completed.

[0080] Among them, the power chip and the copper foil are welded or sintered with metal connecting columns or metal sheets that are not limited to circular, rectangular, elliptical, and square, as well as metal connecting columns that are thin at the bottom and thick at the top. The number of columns or metal sheets in any area on the power chip and the copper foil area can be multiple or single.

[0081] In one embodiment, Figure 4 As shown, a temperature sensor is also arranged between the two metal plates.

[0082] In one embodiment, a metal base is further provided under the power chip, and the shape of the base includes but is not limited to L-shaped, U-shaped, round, and square. Each base has a raised platform for welding or sintering to the upper metal foil, and a recessed part for burying the power chip in the base. Finally, after the power chip is sintered or welded to the recessed part of the base, the top of the power chip and the raised part of the base are kept flat as a whole.

[0083] Embodiment 2:

[0084] This embodiment provides another structure of an embedded power chip covered with a metal foil substrate, such as Figure 5 As shown, it includes: a metal foil, an insulating material, a power chip, a metal connecting column and an insulating substrate covered with metal foil on both sides;

[0085] The method for manufacturing the substrate of this structure includes:

[0086] Soldering or sintering the power chips to the insulating substrate and then soldering or sintering them to the underlying metal foil;

[0087] Soldering or sintering metal connection pillars to the copper foil of the power chip and the insulating substrate;

[0088] Laying the top metal foil sheet on the connecting metal connecting posts, welding or sintering them together;

[0089] The insulating material is filled and solidified between two layers of metal foil plates by injection molding, surrounding the power chip and the insulating substrate.

[0090] The present invention uses the method of sintering metal connecting columns to achieve traditional laser drilling and electroplating. It solves the following problems:

[0091] The hole diameter cannot be too large. Currently, the maximum PCB drilling size is 125um.

[0092] The number of holes cannot be too small. A single 25 square millimeter silicon carbide power chip has more than 300 holes.

[0093] The consistency of drilling depth. The power chip connection layer should be drilled about 5-9um.

[0094] Destroy the connection layer of the power chip.

[0095] The positioning accuracy of drilling holes. The entire PCB will reach 10,800 micro holes.

[0096] Mechanical strength decreases. Too many holes affect mechanical strength.

[0097] High consistency is required for drilling and electroplating. Otherwise, it is very easy to cause the electroplating layer to crack and fail.

[0098] Convenient production and high reliability

[0099] Metal connection pillars, except for the gate of the power chip, which is relatively small at about 0.7mm, there is no size limit for other metal connection pillars. You can flexibly choose the appropriate size to reduce the number according to the current size. At least one power chip has a total of two connection pillars: one gate connection pillar and one source connection pillar.

[0100] The metal connection pillars, power chips, and upper and lower metal copper layers adopt the power chip sintering process, and the connection is very reliable.

[0101] The power chip and the metal connecting column adopt a sintering process, which will not damage the power chip connecting layer.

[0102] No holes are drilled in the upper and lower copper layers, so the entire board is complete with high mechanical strength and reliability.

[0103] Low positioning accuracy requirement

[0104] The minimum metal connection column diameter is about 0.7mm, and the number is very small. The positioning requirements are relatively low.

[0105] Embodiment 3:

[0106] The present invention adopts metal pillars to replace the drilling and electroplating solutions of PCB manufacturers, so that the production efficiency and reliability of power chip connection are improved. Furthermore, the metal pillars or metal sheets can be eliminated to directly weld or sinter the power chip to the metal foil board. The reliability is higher than that of metal pillar connection.

[0107] Figure 6 A new substrate structure diagram provided for this implementation, the production process is as follows:

[0108] Apply solder paste or sintering material on the metal plate, and then place the power chip and metal connection pillars or metal sheets;

[0109] Sintering metal pillars / metal sheets and power chips to the underlying metal plate;

[0110] Laying out and sintering the top metal plate;

[0111] High-pressure injection molding is used to fill the insulating material between the two metal plates. From then on, the entire embedded power chip substrate is completed. The standard PCB production process is then used to produce the circuit pattern by etching.

[0112] Embodiment 4:

[0113] like Figure 7 As shown, this embodiment provides a new substrate structure, and the manufacturing process is as follows:

[0114] Place welding or sintering materials on a metal base with a protruding platform (the shape can be L-shaped, concave, circular with a small pit in the middle, or rectangular or square with a flat bottom pit in the shape of a power chip in the middle). Here we use an L-shaped metal base as an example.

[0115] The power chips are placed on the soldering material or the sintering material, and are soldered or sintered using a sintering machine or a soldering machine.

[0116] Place sintering material or welding material on the bottom metal layer, then place the combined power chip and metal base on the sintering material or welding material and weld or sinter them together using a sintering machine or welding machine.

[0117] Place sintering material or welding material on the signal pins on the top layer of the power chip and on the platform of the metal base.

[0118] A metal layer is placed on the sintering material and the welding material, and a sintering machine or a welding machine is used to sinter or weld the metal layer and the power chip and the metal base underneath together.

[0119] Insulating and sealing materials are filled between the top and bottom metal layers.

[0120] Since then, the entire embedded power chip substrate has been produced. After that, the standard PCB production process is used to produce and etch the circuit pattern.

[0121] Embodiment 5:

[0122] This embodiment provides a new substrate structure, such as Figure 8 As shown, the production process is as follows:

[0123] Apply solder paste or sintering material on the double-sided copper-clad insulating board;

[0124] Place power chips and metal sheets or metal pillars on solder paste or sintering materials, and use a sintering machine to sinter them onto the double-sided copper-clad insulating board below;

[0125] Apply solder paste or sintering material on the double-sided copper clad board;

[0126] Place the previously sintered power chips and insulating plates on the double-sided copper clad laminate, and sinter them with the double-sided copper clad laminate.

[0127] Place sintering materials or welding materials on the power chip and metal connecting sheet.

[0128] Place the metal layer on the sintering material or welding material, and then use a sintering machine to sinter the metal layer and the power chip and metal connecting piece / metal connecting column below together.

[0129] Place the metal layer on the sintering material or welding material, and then use a sintering machine to sinter the metal layer and the power chip and metal connecting piece / metal connecting column below together.

[0130] Fill the insulating sealing filling material between the metal layer and the double-sided copper clad laminate below.

[0131] Drilling from the bottom does not need to penetrate the double-layer copper clad laminate to reach the inner copper-clad insulating material on both sides, but only needs to reach the second layer of the double-layer copper clad laminate.

[0132] The bottom hole is filled with electroplating to form a thermal via.

[0133] Since then, the entire embedded power chip substrate has been produced. After that, the standard PCB production process is used to produce and etch the circuit pattern.

[0134] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0135] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A metal foil substrate with embedded power chip, characterized in that: It includes metal foil, insulating material, power chip and metal connecting column; The method for manufacturing the substrate comprises: Solder or sinter the power chip to the underlying metal foil; Soldering or sintering the metal connection column to the power chip or the underlying metal foil; A layer of metal foil is welded or sintered on top of the column; Fill the insulation material between the two metal sheets.

2. The metal foil-clad substrate with embedded power chip according to claim 1, characterized in that: The production method specifically comprises: Printing sintered silver / copper paste on the bottom copper plate using a printing device; Use the chip placement equipment to attach the bare power chip and some metal connection pillars to the sintered silver / copper paste; Use sintering equipment to sinter the power chip and some metal connection columns to the bottom copper plate at 20Mpa pressure, 260℃, and 5 minutes; Use a glue coating machine to apply sintered silver / copper paste on the upper end of the power chip; Attach the remaining metal connection pillars to the silver / copper paste on the top of the power chip; Use sintering equipment to sinter the metal connection column onto the power chip at 20Mpa pressure, 260°C, and 5 minutes; Use a glue coating machine to apply sintered silver / copper paste on the top of all sintered metal connecting columns; Use a placement machine to attach the top copper plate to the metal connection posts; Use a sintering device to sinter the top copper plate onto the metal connecting column at 20 MPa pressure, 260 degrees Celsius, and 5 minutes; The epoxy resin molding material is injected between two metal plates at 150°C and 50 tons of mold pressure using a plastic packaging machine; all power chips and metal connecting columns between the top and bottom layers are completely contained in the epoxy resin, and the embedded power chip covered metal foil substrate is completed.

3. The metal foil-clad substrate with embedded power chip according to claim 1, characterized in that: The invention also includes: a double-sided metal foil insulating substrate (a substrate with metal on both sides and insulating material in the middle, such as DBC with alumina ceramic in the middle is a common double-sided metal foil insulating substrate); the manufacturing method of the substrate includes: Solder or sinter the power chips to the double-sided copper-clad insulating substrate, and then solder or sinter them to the underlying metal foil; Soldering or sintering metal connection pillars to the copper foil of the power chip and the insulating substrate; Lay the top metal foil sheet on the metal connecting pillars and weld or sinter them together; The insulating material is filled and solidified between the two layers of metal foil plates by a plastic packaging machine, surrounding the power chip and the insulating substrate.

4. The metal foil-clad substrate with embedded power chip according to any one of claims 1 to 3, characterized in that: The metal connection columns or metal sheets welded or sintered on the power chip and the metal foil may be not limited to circular, rectangular, oval, or square. The number of metal connection columns or metal sheets in any area on the power chip and the copper foil area may be multiple or single.

5. The metal foil-clad substrate with embedded power chip according to any one of claims 1 to 3, characterized in that: A temperature sensor is also arranged between the two metal plates.

6. The metal foil-clad substrate with embedded power chip according to any one of claims 1 to 3, characterized in that: A metal base is also provided under the power chip, and the shape of the base includes but is not limited to L-shape, U-shape, circle, and square. Each base has a raised platform for welding or sintering to the upper metal foil, and a recessed part for burying the power chip in the base. Finally, after the power chip is sintered or welded to the groove part of the base, the top of the power chip and the raised part of the base remain flat as a whole.

7. The metal foil-clad substrate with embedded power chip according to any one of claims 1 to 3, characterized in that: The power chip and the upper metal plate are directly welded or sintered to replace metal pillars or metal sheets.

8. The metal foil-clad substrate with embedded power chip according to any one of claims 1 to 3, characterized in that: The power chip and the double-sided copper-clad insulating substrate and the upper and lower metal plates or double-sided copper-clad substrates are directly welded or sintered to replace metal pillars or metal sheets; if the lower layer uses a double-sided copper-clad laminate, the drilling depth of the thermal via does not need to penetrate the copper foil of the inner layer of the double-sided copper-clad laminate. Figure 8 is an implementation case.

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