Wireless power module cooled on both surfaces and manufacturing method therefor

Abstract

The present invention provides a wireless power module cooled on both surfaces, which uses a copper structure for wiring instead of a bonding wire, and a manufacturing method therefor. The wireless power module cooled on both surfaces, according to an embodiment of the present invention, comprises: a first ceramic substrate which comprises a first ceramic layer and a first base copper layer disposed on a first surface of the first ceramic layer; a second ceramic substrate which is disposed to face the first ceramic substrate and comprises a second ceramic layer and a second base copper layer disposed on a third surface of the second ceramic layer; a semiconductor device which is mounted on the first ceramic substrate and comprises a first electrode, a second electrode, and a third electrode; and a copper plug structure which is disposed between the second ceramic substrate and the semiconductor device, electrically connected to the semiconductor device, and formed by printing, compressing and sintering a copper-containing paste.

Description

Wireless double-sided cooling power module and its manufacturing method

[0001] The technical idea of ​​the present invention relates to a power module, and more specifically, to a wireless double-sided cooling power module and a method for manufacturing the same.

[0002] Power semiconductor devices, widely used in mobile devices, home appliances, and automobiles, play a role in converting, processing, and controlling power. Power semiconductor devices, which require high current and voltage for power supply, generate a significant amount of heat, and therefore use ceramic circuit boards made of ceramic materials such as Al2O3, AlN, Zirconia Toughened Alumina (ZTA), and Si3N4. Ceramics have high insulation, mechanical strength, and relatively high heat dissipation performance, making them suitable as substrates for high-power power semiconductor devices. In addition, ceramic circuit boards may include conductive patterns made of aluminum (Al) or copper (Cu), which have high thermal conductivity, on the ceramic material.

[0003] In order to easily dissipate heat generated from power semiconductor devices, a double-sided cooling type power module is being used, which can cool both sides by placing ceramic circuit boards on both sides of the power semiconductor devices. In addition, to dissipate heat from the power module, cooling fins are placed on the outside of the ceramic circuit board, and heat can be transferred to a water cooler installed externally through the cooling fins.

[0004] Conventional techniques for manufacturing such ceramic circuit boards use an etching process to form a conductive layer pattern, which limits the shape of the pattern. In particular, conventional techniques using an etching process have difficulty forming patterns with step thicknesses or multilayer patterns to accommodate various types of power semiconductor devices. Therefore, conventionally, conductive spacers made of a Mo-Cu alloy have been used to secure the step thicknesses of the patterns. However, the Mo-Cu alloy conductive spacers have low thermal conductivity and require an additional process of individually mounting small spacers on the ceramic circuit board, which is a limitation. In addition, attaching cooling fins to the outer surface of the ceramic circuit board has the limitation that sufficient heat transfer between the ceramic circuit board and the cooling fins is not achieved. A method of applying thermal grease to the contact surface to ensure smooth heat transfer between them is also available, but this has limitations in improving heat dissipation performance.

[0005] Furthermore, conventional double-sided cooling power modules use bonding wires to electrically connect power semiconductor elements to the outside world. Therefore, a separate process is required to wire-bond these bonding wires, and there is a risk of the bonding wires being damaged or causing poor connection during manufacturing.

[0006] <Prior Art Document> Korean Patent Publication No. 2014-0127228

[0007] The technical problem to be achieved by the technical idea of ​​the present invention is to provide a wireless double-sided cooling power module that uses a copper structure as a wiring instead of a bonding wire, and a method for manufacturing the same.

[0008] However, these tasks are exemplary and the technical idea of ​​the present invention is not limited thereto.

[0009] According to one aspect of the present invention, a wireless double-sided cooling power module using a copper structure as wiring and a method for manufacturing the same are provided.

[0010] According to one embodiment of the present invention, the wireless double-sided cooling power module may include a first ceramic substrate including a first ceramic layer and a first base copper layer disposed on a first surface of the first ceramic layer; a second ceramic substrate disposed facing the first ceramic substrate and including a second ceramic layer and a second base copper layer disposed on a third surface of the second ceramic layer; a semiconductor element mounted on the first ceramic substrate and including a first electrode, a second electrode, and a third electrode; and a copper structure plug disposed between the second ceramic substrate and the semiconductor element, electrically connected to the semiconductor element, and formed by printing, pressing, and sintering a copper-containing paste.

[0011] According to one embodiment of the present invention, the copper structure plug may include a first copper structure plug electrically connecting the first electrode of the semiconductor element to the second base copper layer of the second ceramic substrate; and a second copper structure plug electrically connecting the second electrode of the semiconductor element to the second base copper layer of the second ceramic substrate.

[0012] According to one embodiment of the present invention, the copper structure plug may further include a third copper structure plug that is disposed between the first base copper layer of the first ceramic substrate and the second base copper layer of the second ceramic substrate, and electrically connects the first base copper layer and the second base copper layer.

[0013] According to one embodiment of the present invention, the third electrode of the semiconductor element can be electrically connected to the first base copper layer of the first ceramic substrate.

[0014] According to one embodiment of the present invention, the copper structure plug may include a region on the upper side having a differential porosity and having a lower porosity than the lower side that is relatively adjacent to the second base copper layer.

[0015] According to one embodiment of the present invention, the copper structure plug may have a porosity that decreases from the lower side relatively adjacent to the second base copper layer toward the upper side.

[0016] According to one embodiment of the present invention, the copper structure plug may have a pyramidal shape whose planar area decreases from the lower side relatively adjacent to the second base copper layer toward the upper side.

[0017] According to one embodiment of the present invention, the copper structure plug may include a base portion; and a surface portion disposed on the base portion and having a lower porosity than the base portion.

[0018] According to one embodiment of the present invention, the base portion may have a porosity in a range of more than 5% by volume and less than or equal to 20% by volume, and the surface portion may have a porosity in a range of more than 0% by volume and less than or equal to 5% by volume.

[0019] According to one embodiment of the present invention, the first ceramic substrate may further include a lead frame electrically connected to the first base copper layer.

[0020] According to one embodiment of the present invention, a mold layer filling a space between the first ceramic substrate and the second ceramic substrate may be further included.

[0021] According to one embodiment of the present invention, the first ceramic substrate may further include a first outer copper layer disposed on a second surface opposite to the first surface, and the second ceramic substrate may further include a second outer copper layer disposed on a fourth surface opposite to the third surface.

[0022] According to one embodiment of the present invention, at least one of the first base copper layer and the second base copper layer may be formed of a TPC copper layer formed by printing, pressing, and sintering a copper-containing paste on the ceramic layer, a DBC copper layer formed by bonding a copper foil on the ceramic layer through a high-temperature oxidation process, a DPC copper layer formed by forming a seed layer on the ceramic layer and then plating the seed layer with copper, or an AMB copper layer formed by bonding a copper foil using an active metal foil to the ceramic layer.

[0023] According to one embodiment of the present invention, at least one of the first base copper layer and the second base copper layer may include at least one of a bonding copper layer, a laminated copper layer, and a surface copper layer.

[0024] According to one embodiment of the present invention, the bonding copper layer may be formed using a copper-containing bonding paste including glass frit, inorganic particles, copper oxide particles, copper particles, a solvent, and a binder, the laminated copper layer may be formed using a copper-containing laminated paste including inorganic particles, copper particles, a solvent, and a binder, and the surface copper layer may be formed using a copper-containing surface paste including copper oxide particles, copper particles, a solvent, and a binder.

[0025] According to one embodiment of the present invention, a method for manufacturing the wireless double-sided cooling power module may include the steps of: providing a first ceramic substrate including a first ceramic layer and a first base copper layer disposed on a first surface of the first ceramic layer; providing a second ceramic substrate disposed facing the first ceramic substrate and including a second ceramic layer and a second base copper layer disposed on a third surface of the second ceramic layer; mounting a semiconductor element on the first ceramic substrate; forming a copper structure plug by printing, pressing, and sintering a copper-containing paste at a temperature ranging from 500° C. to 700° C. on the second base copper layer of the second ceramic substrate; and arranging the first ceramic substrate and the second ceramic substrate to face each other and bonding the semiconductor element and the copper structure plug.

[0026] According to one embodiment of the present invention, the step of forming the copper structure plug may be performed such that the copper structure plug has a differential porosity and includes a region on the upper side having a lower porosity than a lower side that is relatively adjacent to the second base copper layer.

[0027] According to one embodiment of the present invention, in the step of forming the copper structure plug, the printing step and the pressing step are performed in one cycle to form one paste layer, and then the printing step and the pressing step are performed again to form a subsequent paste layer on the previously formed paste layer, thereby repeating the process to form a plurality of paste layers, and the plurality of paste layers are sintered together.

[0028] According to one embodiment of the present invention, in the step of forming the copper structure plug, when performing the printing step, the application area of ​​the copper paste is reduced from the lower side adjacent to the second base copper layer toward the upper side, thereby allowing the copper structure plug to have a pyramidal shape.

[0029] According to one embodiment of the present invention, the first ceramic substrate may include a first active metal brazing layer interposed between the first ceramic layer and the first base copper layer, and the second ceramic substrate may include a second active metal brazing layer interposed between the second ceramic layer and the second base copper layer.

[0030] The ceramic substrate according to the present invention has the advantage of being able to form a three-dimensional pattern on the ceramic substrate using a copper structure plug formed by printing, pressing, and sintering so as to be able to respond to various types of semiconductor devices mounted on the substrate.

[0031] Furthermore, since the copper structure plug is used in place of the bonding wire, the wire bonding process is not required, and electrical and thermal conductivity are improved, along with durability against thermal cycles. Furthermore, since bonding wires are not used, disadvantages such as heat loss, power loss, and reduced durability caused by bonding wires can be eliminated, reducing process costs and the defect rate.

[0032] In addition, since the above copper structure plug is a sintered material rather than a rolled material, there are differences in the microstructure, such as not having the directionality that appears in a rolled material, and there are differences in the degree of inclusion and distribution of pores.

[0033] In addition, the copper structure plug does not require a molybdenum / copper spacer to be formed and attached in a separate process, and is printed, pressed, and fired at once using a 3D TPC method using a copper-containing paste, thereby providing excellent positional accuracy, minimizing spacer thickness deviation, and further preventing damage to semiconductor devices.

[0034] While the Mo-Cu spacer according to the prior art has a porosity of about 0% and thus has high thermal stress and low thermal fatigue characteristics, the copper structure plug according to the present invention includes a lower layer having a high porosity, thereby providing low thermal stress and improved resistance to thermal fatigue destruction, and further includes an upper layer having a low porosity, thereby preventing bonding defects in power semiconductor devices.

[0035] The method for manufacturing a wireless double-sided cooling power module according to the present invention can prevent the formation of defects due to heat by performing sintering of a copper structure plug at a temperature ranging from 500°C to 800°C. In addition, by performing surface blasting treatment, copper oxide formed on the surface of the copper structure plug during sintering can be removed to provide a smooth surface, thereby ensuring stable electrical connection between the copper structure plug and the power semiconductor element.

[0036] The effects of the present invention described above are illustrative, and the scope of the present invention is not limited by these effects.

[0037] FIGS. 1 and 2 are cross-sectional views illustrating a wireless double-sided cooling power module according to one embodiment of the present invention.

[0038] FIG. 3 is a schematic diagram illustrating a power semiconductor element included in a wireless double-sided cooling power module according to one embodiment of the present invention.

[0039] FIGS. 4 and 5 are cross-sectional views illustrating a wireless double-sided cooling power module according to one embodiment of the present invention.

[0040] FIG. 6 is a cross-sectional view illustrating a first base copper layer included in a wireless double-sided cooling power module according to one embodiment of the present invention.

[0041] FIG. 7 is a cross-sectional view illustrating a copper structure plug included in a wireless double-sided cooling power module according to one embodiment of the present invention.

[0042] FIG. 8 is a photograph showing the microstructure of a copper structure plug included in a wireless double-sided cooling power module according to one embodiment of the present invention.

[0043] FIGS. 9A and 9B are cross-sectional views and photographs showing a pyramid-shaped copper structure of a ceramic circuit board according to one embodiment of the present invention.

[0044] FIG. 10 is a flowchart illustrating a method for manufacturing a wireless double-sided cooling power module according to an embodiment of the present invention.

[0045] Fig. 11 is an ultrasonic inspection result showing whether a defect occurs according to the sintering temperature of a ceramic substrate included in a wireless double-sided cooling power module according to an embodiment of the present invention.

[0046] FIG. 12 is a photograph showing the surface condition of a ceramic substrate included in a wireless double-sided cooling power module according to one embodiment of the present invention before and after blasting treatment.

[0047] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Embodiments of the present invention are provided to more completely explain the technical idea of ​​the present invention to those skilled in the art. The following embodiments may be modified in various different forms, and the scope of the technical idea of ​​the present invention is not limited to the following embodiments. Rather, these embodiments are provided to more faithfully and completely convey the technical idea of ​​the present invention to those skilled in the art. Like reference numerals throughout this specification denote like elements. Furthermore, various elements and areas in the drawings are schematically drawn. Therefore, the technical idea of ​​the present invention is not limited by the relative sizes or intervals drawn in the attached drawings.

[0048] In this specification, a layer formed "on" another layer may refer to a layer formed directly above the other layer, or may refer to an intermediate layer or layers formed on another layer. It should be noted that the meanings of "upper" and "lower" in this specification are relative, and the direction upward from the ceramic substrate is described as "upper", and the direction downward is described as "lower."

[0049] In this specification, power semiconductor devices are exemplary, and cases composed of other semiconductor devices are also included in the technical concept of the present invention.

[0050] FIGS. 1 and 2 are cross-sectional views illustrating a wireless double-sided cooling power module according to one embodiment of the present invention.

[0051] Referring to FIG. 1, a wireless double-sided cooling power module (100) includes a first ceramic substrate (110), a second ceramic substrate (120), a power semiconductor element (130), a first copper structure plug (140), a second copper structure plug (150), a third copper structure plug (160), and a mold layer (170). In addition, the wireless double-sided cooling power module (100) may further include a lead frame (180).

[0052] Referring to FIG. 2, a wireless double-sided cooling power module (100a) includes a first ceramic substrate (110a), a second ceramic substrate (120a), a power semiconductor element (130), a first copper structure plug (140), a second copper structure plug (150), a third copper structure plug (160), and a mold layer (170). In addition, the wireless double-sided cooling power module (100a) may further include a lead frame (180).

[0053] Hereinafter, components of a wireless double-sided cooling power module will be described in detail with reference to FIGS. 1 and 2.

[0054] The first ceramic substrate (110) may include a first ceramic layer (112), a first base copper layer (114), and a first outer copper layer (116). The second ceramic substrate (120) may include a second ceramic layer (122), a second base copper layer (124), and a second outer copper layer (126). The first ceramic substrate (110) and the second ceramic substrate (120) may be disposed facing each other.

[0055] The first ceramic substrate (110a) may include a first ceramic layer (112), a first base copper layer (114), a first outer copper layer (116), and a first active metal brazing layer (118). The second ceramic substrate (120a) may include a second ceramic layer (122), a second base copper layer (124), a second outer copper layer (126), and a second active metal brazing layer (128). The first ceramic substrate (110a) and the second ceramic substrate (120a) may be disposed facing each other.

[0056] Compared with FIG. 1, the first ceramic substrate (100a) of FIG. 2 has a difference in that it further includes a first active metal brazing layer (118), and the second ceramic substrate (200a) has a difference in that it further includes a second active metal brazing layer (128). The first active metal brazing layer (118) may be interposed between the first ceramic layer (112) and the first base copper layer (114) and between the first ceramic layer (112) and the first outer copper layer (116). The second active metal brazing layer (128) may be interposed between the second ceramic layer (122) and the second base copper layer (124) and between the second ceramic layer (122) and the second outer copper layer (126).

[0057] The first ceramic layer (112) may have a first surface (1121) and a second surface (1122) that face each other. In FIGS. 1 and 2, the first surface (1121) is depicted as the upper surface and the second surface (1122) is depicted as the lower surface with respect to the first ceramic layer (112).

[0058] The second ceramic layer (122) may have a third surface (121) and a fourth surface (1222) that face each other. In FIGS. 1 and 2, the third surface (1121) is depicted as the lower surface and the fourth surface (1122) is depicted as the lower surface with respect to the second ceramic layer (122).

[0059] The first ceramic layer (112) and the second ceramic layer (122) may have excellent thermal conductivity and electrical insulation. The first ceramic layer (112) and the second ceramic layer (122) may be made of a ceramic material, and may include, for example, at least one of Al2O3, AlN, Zirconia Toughened Alumina (ZTA), and Si3N4.

[0060] The first base copper layer (114) may be disposed on the first surface (1121) of the first ceramic layer (112). The second base copper layer (124) may be disposed on the third surface (1121) of the second ceramic layer (122). The first base copper layer (114) of the first ceramic substrate (110) and the second base copper layer (124) of the second ceramic substrate (120) may be disposed so as to face each other adjacent to each other.

[0061] The first base copper layer (114) and the second base copper layer (124) can be formed using TPC technology, DBC technology, DPC technology, or AMB technology. The first base copper layer (114) and the second base copper layer (124) can have a total thickness ranging from, for example, 100 μm to 1000 μm, and can have a total thickness of, for example, about 300 μm.

[0062] The first base copper layer (114) and the second base copper layer (124) may be formed as TPC (thick printed copper) copper layers using TPC technology. The TPC technology may refer to a technology for forming a copper layer having a predetermined thickness by printing, pressing, and sintering using a copper-containing paste. The TPC copper layer may be formed by printing a copper-containing paste on one or both sides of a ceramic layer to form a paste layer, and pressing and sintering the paste layer. Since the TPC technology forms the TPC copper layer using a screen printing method, it does not require an additional etching process and can freely implement various patterning shapes. In addition, the TPC technology may allow a layer formed in one process cycle of printing, pressing, and sintering to have a very small thickness, and the layer may have a thickness in the range of, for example, 10 μm to 100 μm. In addition, since the thickness of the TPC copper layer can be increased by repeatedly performing the above process cycle to form multiple layers, thickness control can be facilitated. In addition, the TPC copper layer can secure overall uniformity in thickness, surface quality, etc. In addition, nickel (Ni), silver (Ag), gold (Au), etc. can be plated on the TPC copper layer.

[0063] In addition, the first base copper layer (114) and the second base copper layer (124) may be formed as DBC copper layers formed using DBC (direct bonded copper) technology. The DBC technology may refer to a technology of forming a copper layer by directly attaching a copper foil to a ceramic layer. The DBC copper layer may be formed by placing a copper foil on one or both sides of a ceramic layer, performing a high-temperature oxidation process at a temperature in the range of 1000°C to 1080°C, and bonding the copper foil to the ceramic layer using a copper-oxygen eutectic liquid. The bonding may be performed in a nitrogen atmosphere containing about 30 ppm of oxygen at a temperature lower than 1083°C, which is the melting point of copper, and forming a copper oxide layer on the surface of the copper foil to implement bonding with the ceramic layer. Subsequently, if necessary, the DBC copper layer may be patterned using an etching process. Additionally, nickel (Ni), silver (Ag), gold (Au), etc. can be plated on the DBC copper layer.

[0064] In addition, the first base copper layer (114) and the second base copper layer (124) may be formed as DPC copper layers formed using DPC (direct plating copper) technology. The DPC technology may refer to a technology for forming a copper layer by using a thin film process, an etching process, and a plating process. The DPC copper layer may be formed by forming a seed layer of titanium (Ti), titanium-tungsten (TiW), or the like on one or both sides of a ceramic layer, and then plating copper (Cu) on the seed layer. In addition, a photoresist pattern may be formed on the seed layer, and then copper (Cu) may be plated on the photoresist pattern, and the photoresist pattern may be removed to form the DPC copper layer having a desired pattern. Subsequently, if necessary, the DPC copper layer may be patterned using an etching process.

[0065] In addition, the first base copper layer (114) and the second base copper layer (124) may be formed of an AMB (active metal brazing) copper layer formed using an AMB technology. The AMB technology may refer to a technology of bonding a ceramic layer and a copper layer using an active metal foil. An active metal foil and a copper foil are sequentially placed on one or both sides of a ceramic layer, and heated to melt the active metal foil. As illustrated in FIG. 2, the ceramic layer and the copper foil are bonded to each other by forming an active metal brazing layer. Accordingly, the active metal brazing layer may perform a role of bonding the ceramic layer and the first base copper layer and a role of bonding the ceramic layer and the second base copper layer. Subsequently, if necessary, the AMB copper layer may be patterned using an etching process.

[0066] The active metal brazing layer may include a metal or metal alloy having a lower melting point than the copper constituting the copper foil, and may include, for example, an active metal alloy in which copper, aluminum, nickel, or silver is added to titanium, hafnium, nickel, molybdenum, or zirconium, which are active toward oxygen, to lower the melting point. The active metal brazing layer may include, for example, an alloy including at least one of silver (Ag), copper (Cu), and titanium (Ti). However, this is exemplary, and the active metal brazing layer may include at least one of aluminum (Al), titanium (Ti), nickel (Ni), niobium (Nb), and molybdenum (Mo).

[0067] The first outer copper layer (116) may be disposed on a second surface (1122) opposite to the first surface (1121) of the first ceramic layer (112). The second outer copper layer (126) may be disposed on a fourth surface (1222) opposite to the third surface (1121) of the second ceramic layer (122).

[0068] The first outer copper layer (116) and the second outer copper layer (126) can function as a warpage prevention layer that prevents the ceramic layer (122) from warping during the sintering process for forming the first base copper layer (114) and the second base copper layer (124) and the sintering process for forming the first copper structure plug (140), the second copper structure plug (150), and the third copper structure plug (160). In addition, the first outer copper layer (116) and the second outer copper layer (126) can provide a path for dissipating heat generated from the power semiconductor device to the outside. For this purpose, a heat dissipation structure (not shown) can be attached to the first outer copper layer (116) and the second outer copper layer (126). The first outer copper layer (116) and the second outer copper layer (126) can be formed as a single layer or as a plurality of layers.

[0069] The first outer copper layer (116) and the second outer copper layer (126) can be formed in the same manner as the first base copper layer (114) and the second base copper layer (124). The first outer copper layer (116) and the second outer copper layer (126) can be formed using the above-described TPC technology, DBC technology, DPC technology, or AMB technology. The first outer copper layer (116) and the second outer copper layer (126) can each include the same material as the first base copper layer (114) and the second base copper layer (124), and can be formed simultaneously.

[0070] As illustrated in FIG. 2, the first active metal brazing layer (118) may be disposed on the first side (1121) and the second side (1122) of the first ceramic layer (112). The first base copper layer (114) may be disposed on the first active metal brazing layer (118) of the first side (1121). The first active metal brazing layer (118) may be interposed between the first ceramic layer (112) and the first base copper layer (114), thereby bonding the first ceramic layer (112) and the first base copper layer (114) to each other. In addition, the first outer copper layer (116) may be disposed on the first active metal brazing layer (118) of the second side (1122). A first active metal brazing layer (118) is interposed between the first ceramic layer (112) and the first outer copper layer (116), so that the first ceramic layer (112) and the first outer copper layer (116) can be bonded to each other.

[0071] Additionally, the second active metal brazing layer (128) may be disposed on the third side (1221) and the fourth side (1222) of the second ceramic layer (122). The second base copper layer (124) may be disposed on the second active metal brazing layer (128) of the third side (1221). The second active metal brazing layer (128) may be interposed between the second ceramic layer (122) and the second base copper layer (124), thereby bonding the second ceramic layer (122) and the second base copper layer (124) to each other. Additionally, the second outer copper layer (126) may be disposed on the second active metal brazing layer (128) of the fourth side (1222). A second active metal brazing layer (128) is interposed between the second ceramic layer (122) and the second outer copper layer (126), so that the first ceramic layer (122) and the second outer copper layer (126) can be bonded to each other.

[0072] In order to form a pattern on the first base copper layer (114) and the second base copper layer (124), an additional etching process may be required when applying the DBC technology, the DPC technology, or the AMB technology. Therefore, when using such an etching process, there is a limitation in that there is a limitation in the pattern shape, and it may be difficult to make a difference in thickness between patterns or to form a second pattern and a third pattern on the pattern in order to respond to various types of semiconductor devices. On the other hand, when applying the TPC technology to form the first base copper layer (114) or the second base copper layer (124), the pattern can be easily formed during printing, and an additional etching process may not be required.

[0073] In order to form a pattern on the first base copper layer (114) and the second base copper layer (124), an additional etching process may be required when applying the DBC technology, the DPC technology, or the AMB technology. Therefore, when using such an etching process, there is a limitation in that there is a limitation in the pattern shape, and it may be difficult to make a difference in thickness between patterns or to form a second pattern and a third pattern on the pattern in order to respond to various types of semiconductor devices. On the other hand, when applying the TPC technology to form the first base copper layer (114) and the second base copper layer (124), the pattern can be easily formed during printing, and an additional etching process may not be required.

[0074] At least one power semiconductor element (130) may be placed between a first ceramic substrate (110) and a second ceramic substrate (120). The first ceramic substrate (110) and the second ceramic substrate (120) may perform a function of dissipating heat generated in the power semiconductor element (130) to the outside. For this heat dissipation, a heat dissipation structure (not shown) may be placed on the outer surface of at least one of the first ceramic substrate (110) and the second ceramic substrate (120). The power semiconductor element (130) may be attached to the first base copper layer (114) of the first ceramic substrate (110) using various attachment layers and attachment methods, such as a conductive adhesive layer and a conductive solder layer, which are exemplary and the technical idea of ​​the present invention is not limited thereto.

[0075] The power semiconductor element (130) may be, for example, a GTO (gate turn-off thyristor) semiconductor element or an IGBT (insulated gate bipolar mode transistor) semiconductor element, and may perform an operation of converting power supplied from a power supply unit such as a battery into power for driving a motor through a switching operation and supplying the converted power. The case where the power semiconductor element (130) is another semiconductor element is also included in the technical concept of the present invention.

[0076] Additionally, the power semiconductor element (130) may include electrode members formed on the upper and lower portions. This will be described with reference to FIG. 3.

[0077] FIG. 3 is a schematic diagram illustrating a power semiconductor element included in a wireless double-sided cooling power module according to one embodiment of the present invention.

[0078] Referring to FIG. 3, the power semiconductor device (130) may include a first electrode (131) and a second electrode (132) on a first side (138), and a third electrode (133) on a second side (139) opposite to the first side (138). For example, the first electrode (131) may be referred to as an emitter electrode, the second electrode (132) as a gate electrode or a collector electrode, and the third electrode (133) as a base electrode. The first electrode (131) and the second electrode (132) may be separated from each other and disposed on the first side (138) for insulation. The second electrode (132) may have a smaller area than the first electrode (131). However, the arrangement of these electrodes is exemplary and the technical idea of ​​the present invention is not limited thereto.

[0079] Referring again to FIGS. 1 and 2, the first copper structure plug (140), the second copper structure plug (150), and the third copper structure plug (160) can be formed using the above-described TPC technique of forming a copper layer by printing, pressing, and sintering.

[0080] The first copper structure plug (140) is placed between the second ceramic substrate (120) and the power semiconductor element (130), and can electrically connect the first electrode (131) of the power semiconductor element (130) to the second base copper layer (124) of the second ceramic substrate (120).

[0081] The second copper structure plug (150) is disposed between the second ceramic substrate (120) and the power semiconductor element (130), and can electrically connect the second electrode (132) of the power semiconductor element (130) to the second base copper layer (124) of the second ceramic substrate (120).

[0082] The third copper structure plug (160) is disposed between the first ceramic substrate (110) and the second ceramic substrate (120), and can electrically connect the first base copper layer (114) of the first ceramic substrate (110) and the second base copper layer (124) of the second ceramic substrate (120).

[0083] The third electrode (133) of the power semiconductor element (130) can be electrically connected to the first base copper layer (114) of the first ceramic substrate (110).

[0084] At least one of the first copper structure plug (140), the second copper structure plug (150), and the third copper structure plug (160) can allow a high current to flow from the power semiconductor element (130).

[0085] The first copper structure plug (140), the second copper structure plug (150), and the third copper structure plug (160) can perform the function of a spacer in addition to the electrical connection described above.

[0086] The mold layer (170) can fill the space between the first ceramic substrate (110) and the second ceramic substrate (120). The mold layer (170) can surround the power semiconductor element (130), the first copper structure plug (140), the second copper structure plug (150), and the third copper structure plug (160) and insulate them from each other. The mold layer (170) can be made of, for example, an epoxy molding compound (EMC).

[0087] The lead frame (180) can be electrically connected to the first base copper layer (114) of the first ceramic substrate (110) and can provide an electrical connection to the outside. In addition, the case where the lead frame (180) can be electrically connected to the second base copper layer (124) of the second ceramic substrate (120) and provides an electrical connection to the outside is also included in the technical concept of the present invention. In addition, a part of the lead frame (180) can be covered by the mold layer (170). The lead frame (180) can include a conductive material, for example, can include a metal.

[0088] Below, the electrical path of the wireless double-sided cooling power module (100) will be described. However, this is exemplary and the technical idea of ​​the present invention is not limited thereto.

[0089] The first electrode (131) of the power semiconductor element (130) can be electrically connected to the outside through an electrical path composed of a first copper structure plug (140), a second base copper layer (124), a third copper structure plug (160), a first base copper layer (114), and a lead frame (180).

[0090] The second electrode (132) of the power semiconductor element (130) can be electrically connected to the outside through an electrical path composed of a second copper structure plug (150), a second base copper layer (124), a third copper structure plug (160), a first base copper layer (114), and a lead frame (180).

[0091] The third electrode (133) of the power semiconductor element (130) can be electrically connected to the outside through an electrical path composed of the first base copper layer (114) and the lead frame (180).

[0092] The first electrode (131), the second electrode (132), and the third electrode (133) of the power semiconductor element (130) can be electrically insulated from each other within the wireless double-sided cooling power module (100).

[0093] The first base copper layer (114), the second base copper layer (124), and the lead frame (180) may have an appropriate pattern shape to provide the electrical path described above.

[0094] FIGS. 4 and 5 are cross-sectional views illustrating a wireless double-sided cooling power module according to one embodiment of the present invention.

[0095] Referring to FIG. 4, a wireless double-sided cooling power module (100b) includes a first ceramic substrate (110a) including a first active metal brazing layer (118) and a second ceramic substrate (120) not including an active metal brazing layer. Descriptions of components identical or similar to those in the above-described embodiment will be omitted.

[0096] Referring to FIG. 5, a wireless double-sided cooling power module (100c) includes a first ceramic substrate (110) that does not include an active metal brazing layer and a second ceramic substrate (120a) that includes a second active metal brazing layer (128). Descriptions of components identical or similar to those in the above-described embodiment will be omitted.

[0097] The first base copper layer (114) and the second base copper layer (124) may be copper foil formed by DBC technology or AMB technology, or may be a copper plating layer formed by DPC technology. Alternatively, the first base copper layer (114) and the second base copper layer (124) may be a sintered body of a copper-containing paste formed by TPC technology.

[0098] Below, the first base copper layer (114) and the second base copper layer (124) formed using TPC (thick printed copper) technology will be described in detail.

[0099] FIG. 6 is a cross-sectional view illustrating a first base copper layer included in a wireless double-sided cooling power module according to one embodiment of the present invention.

[0100] Referring to FIG. 6, the first base copper layer (114) can be formed by printing a copper-containing paste to form a paste layer and pressing and sintering the paste layer.

[0101] The first base copper layer (114) may be disposed on a portion of the first ceramic layer (112). The first base copper layer (114) may be formed using the TPC technology described above.

[0102] The first base copper layer (114) may be composed of a plurality of layers. The first base copper layer (114) may include, for example, at least one of a bonding copper layer (1141), a laminated copper layer (1142), and a surface copper layer (1143).

[0103] The thickness of the first base copper layer (114) can be varied by controlling the thickness of the relatively thick laminated copper layer (1142). The laminated copper layer (1142) can have a greater thickness than the bonded copper layer (1141) and the surface copper layer (1143). The bonded copper layer (1141) and the surface copper layer (1143) can have the same thickness or different thicknesses. The bonded copper layer (1141) can have a thickness in the range of, for example, 1 μm to 100 μm, for example, about 20 μm. The laminated copper layer (1142) can have a thickness in the range of, for example, 100 μm to 1000 μm. The surface copper layer (1143) can have a thickness in the range of, for example, 1 μm to 100 μm, for example, about 30 μm.

[0104] The bonding copper layer (1141) may be disposed on at least a portion of the first ceramic layer (112). The laminated copper layer (1142) may be disposed on the bonding copper layer (1141). The surface copper layer (1143) may be disposed on the laminated copper layer (1142). However, this is exemplary and the technical idea of ​​the present invention is not limited thereto. For example, when the thickness of the first base copper layer (114) is not thick, the first base copper layer (114) may be configured to include the bonding copper layer (1141) and the surface copper layer (1143), excluding the laminated copper layer (1142). Alternatively, when a power semiconductor element is not bonded on the first base copper layer (114), the first base copper layer (114) may be configured to include a bonding copper layer (1141) and a laminated copper layer (1142), excluding the surface copper layer (1143).

[0105] The bonding copper layer (1141) can be formed by forming a bonding paste layer by printing a copper-containing bonding paste on the first ceramic layer (112) using a screen printing method or the like, drying to remove the solvent, pressing the dried bonding paste layer, and then heating to sinter it.

[0106] The laminated copper layer (1142) can be formed by printing a copper-containing laminated paste on the bonding copper layer (1141) using a screen printing method or the like to form a laminated paste layer, then drying to remove the solvent, pressing the dried laminated paste layer, and then heating to sinter it.

[0107] The surface copper layer (1143) can be formed by printing a copper-containing surface paste on the laminated copper layer (1142) using a screen printing method or the like to form a surface paste layer, then drying to remove the solvent, pressing the dried surface paste layer, and then heating to sinter it.

[0108] By the above pressing, the internal pores of the bonding paste layer, the laminated paste layer, and the surface paste layer can be reduced and the uniformity of height can be secured.

[0109] The above-described printing, pressing, and sintering steps may be performed repeatedly. For example, after forming one paste layer in one cycle of the printing and pressing, the printing and pressing may be performed again to form a subsequent paste layer on the previously formed paste layer, and this may be repeated to form a plurality of paste layers. The plurality of paste layers may be sintered together. In addition, by repeatedly performing the sintering, the copper layer may be formed. That is, sintering may be performed one or more times for one copper layer constituting the first base copper layer (114). The number of times of the printing, pressing, and sintering may vary.

[0110] Below, the materials constituting the above-described paste forming the first base copper layer (114) will be described.

[0111] The copper-containing bonding paste may include, for example, copper particles, glass frit, inorganic particles, copper oxide particles, a solvent, and a binder.

[0112] The copper-containing laminate paste may include, for example, copper particles, inorganic particles, a solvent, and a binder. Compared to the copper-containing bonding paste, the copper-containing laminate paste may not include glass frit and copper oxide particles.

[0113] The copper-containing surface paste may include copper particles, copper oxide particles, a solvent, and a binder. Compared to the copper-containing bonding paste, the copper-containing surface paste may not include glass frit and inorganic particles.

[0114] The above glass frit is a sintering aid that helps sintering of copper (Cu) particles and can provide better bonding between the first ceramic layer (112) and the bonding copper layer (1141).

[0115] The above inorganic particles may include powder of at least one of Al2O3, CaO, and ZrO2. The above inorganic particles may function to reduce the shrinkage rate of the paste. For reference, the shrinkage rate can be measured by printing the paste into a disk shape, drying and sintering it, and comparing the diameter of the disk after drying and after sintering.

[0116] The above copper oxide particles may include at least one of CuO and Cu2O, and may perform a function of improving bonding properties with the components to be bonded. The copper oxide particles may form a process liquid phase during the sintering process. For example, when the first ceramic layer (112) includes alumina (Al2O3), the copper oxide may react with alumina to form CuAlO2, CuAl2O4, etc., thereby improving bonding properties.

[0117] The copper particles may be composed of copper and may be a main component constituting the first base copper layer (114). The copper particles may include fine copper particles having an average particle diameter ranging from 1 μm to 10 μm and may be included in an amount of 60 wt% to 95 wt% of the paste.

[0118] The shrinkage rate of the copper-containing laminate paste may be higher than the shrinkage rate of the copper-containing bonding paste. The shrinkage rate of the copper-containing surface paste may be higher than the shrinkage rate of the copper-containing bonding paste and the shrinkage rate of the copper-containing bonding paste. The shrinkage rate of the copper-containing bonding paste may be, for example, 0% to 3%. The shrinkage rate of the copper-containing laminate paste may be, for example, 3% to 9%. The shrinkage rate of the copper-containing surface paste may be, for example, 10% to 15%.

[0119] The copper-containing bonding paste, the copper-containing laminate paste, and the copper-containing surface paste can change the types and contents of glass frit, inorganic particles, copper oxide particles, copper particles, solvent, and binder in order to achieve a desired thermal expansion coefficient and shrinkage rate.

[0120] The description of the composition and paste for the first base copper layer (114) described above can be equally applied to the second base copper layer (124). For example, the second base copper layer (124) can include a bonding copper layer, a laminated copper layer, and a surface copper layer, similarly to the first base copper layer (114) described above.

[0121] Hereinafter, a first copper structure plug (140), a second copper structure plug (150), and a third copper structure plug (160) formed using TPC (thick printed copper) technology will be described in detail. The first copper structure plug (140), the second copper structure plug (150), and the third copper structure plug (160) may be sintered bodies of copper-containing paste formed using TPC technology.

[0122] FIG. 7 is a cross-sectional view illustrating a copper structure plug included in a wireless double-sided cooling power module according to one embodiment of the present invention.

[0123] Referring to FIG. 7, the first copper structure plug (140), the second copper structure plug (150), and the third copper structure plug (160) can be formed by commonly printing and drying a copper-containing paste to form a paste layer, and then pressing and sintering the paste layer. The first copper structure plug (140), the second copper structure plug (150), and the third copper structure plug (160) can be formed using the TPC technology described above.

[0124] The first copper structure plug (140) is designed to reduce the difference in thermal expansion coefficient with the power semiconductor element, for example, 5 x 10 -6 / ℃ to 20 x 10 -6 / ℃ can have a coefficient of thermal expansion in the range.

[0125] The first copper structure plug (140) may be a porous porous structure having pores therein. The first copper structure plug (140) may have a differential porosity. This means that the first copper structure plug (140) includes a region on the upper side having a lower porosity than the lower side that is relatively adjacent to the second base copper layer (124).

[0126] For example, the first copper structure plug (140) may have a porosity that decreases from the lower side relatively adjacent to the first base copper layer (114) toward the upper side.

[0127] For example, the first copper structure plug (140) may be composed of a plurality of layers and may include a first base portion (141) and a first surface portion (142) disposed on the first base portion (141) and having a lower porosity than the first base portion (141). The first base portion (141) may have a porosity in a range of, for example, more than 5% by volume and less than or equal to 20% by volume. The first surface portion (142) may have a porosity in a range of, for example, more than 0% by volume and less than or equal to 5% by volume.

[0128] Since the first base (141) has a relatively high porosity, the pores perform a buffer function against thermal shock, thereby reducing thermal stress and increasing resistance to thermal fatigue destruction due to thermal stress under repeated thermal history.

[0129] On the other hand, since the first surface portion (142) has a relatively low porosity, it can have a smooth surface, and thus the bonding of the power semiconductor elements in contact can be improved. If the first surface portion (142) has a high porosity, void defects may remain on the bonding surface due to the pores, which may result in poor bonding of the power semiconductor elements. Therefore, it is preferable to control the first surface portion (142) so that there are no pores or the porosity is low.

[0130] To control this porosity, the particle size and fraction of copper particles included in the paste can be controlled. If the particle size of the copper particles is large or the fraction is low, the porosity can increase, and if the particle size of the copper particles is small or the fraction is large, the porosity can decrease.

[0131] The first paste forming the first base portion (141) may include copper particles having an average particle diameter in a range of more than 3 μm and less than or equal to 10 μm. The second paste forming the first surface portion (142) may include copper particles having an average particle diameter in a range of 100 nm to 3 μm. That is, the average particle diameter of the copper particles included in the second paste may be smaller than the average particle diameter of the copper particles included in the first paste. Due to this difference in the average particle diameter of the copper particles, the first surface portion (142) may have a denser microstructure and a lower porosity than the first base portion (141).

[0132] The first copper structure plug (140) may vary in thickness for electrical connection. The first base portion (141) may have a greater thickness than the first surface portion (142). The first surface portion (142) may have a thickness ranging from 1 μm to 100 μm, for example, about 20 μm.

[0133] The first copper structure plug (140) can be formed using the TPC technology described above. The first copper structure plug (140) can be formed using a copper-containing paste including copper particles, inorganic particles, a solvent, and a binder. The copper-containing paste may further include copper oxide particles. The first copper structure plug (140) can be formed by printing the copper-containing paste using a screen printing method or the like to form a paste layer, drying to remove the solvent, pressing the dried paste layer, and then heating to sinter it.

[0134] The above-described printing, pressing, and sintering steps may be performed repeatedly. For example, after forming one paste layer in one cycle of the printing and pressing, the printing and pressing may be performed again to form a subsequent paste layer on the previously formed paste layer, and this may be repeated a plurality of times to form a plurality of paste layers. The plurality of paste layers may be sintered together. In addition, by repeatedly performing the sintering, the copper layer may be formed. That is, sintering may be performed one or more times for one copper layer constituting the first copper structure plug (140). The number of times of the printing, pressing, and sintering may vary.

[0135] The first copper structure plug (140) may have a surface from which oxides have been removed by blasting treatment.

[0136] The description of the configuration and paste for the first copper structure plug (140) described above can be equally applied to the second copper structure plug (150) and the third copper structure plug (160). For example, the second copper structure plug (150) can include a second base portion (151) and a second surface portion (152), which correspond to the first base portion (141) and the first surface portion (142), respectively. The third copper structure plug (160) can include a third base portion (161) and a third surface portion (162), which correspond to the first base portion (141) and the first surface portion (142), respectively.

[0137] The second copper structure plug (150) and the third copper structure plug (160) may be porous structures having pores therein. The second copper structure plug (150) and the third copper structure plug (160) may have differential porosities. This means that the second copper structure plug (150) and the third copper structure plug (160) include a region on the upper side having a lower porosity than the lower side relatively adjacent to the second base copper layer (124). The second copper structure plug (150) and the third copper structure plug (160) may have a porosity that decreases from the lower side relatively adjacent to the second base copper layer (124) toward the upper side.

[0138] FIG. 8 is a photograph showing the microstructure of a copper structure plug included in a wireless double-sided cooling power module according to one embodiment of the present invention.

[0139] Referring to Fig. 8, the internal pores of the first base portion (141) and the first surface portion (142) of the first copper structure plug (140) are shown. Compared to the first base portion (141), the first surface portion (142) has a low porosity, and the size of each pore is also small. That is, the first surface portion (142) has a dense microstructure.

[0140] When the porosity was 0%, it exhibited a high thermal stress of 220 MPa, whereas when the porosity was 7.7%, it exhibited a thermal stress of 136 MPa, and when the porosity was 17.2%, it exhibited a thermal stress of 114 MPa. In other words, it can be seen that as the porosity increases, the thermal stress decreases. In addition, when the porosity was 7.7%, it exhibited thermal fatigue failure characteristics of 1000 cycles, and when the porosity was 17.2%, it exhibited improved thermal fatigue failure characteristics of 2000 cycles. In other words, it can be seen that as the porosity increases, the resistance to thermal fatigue failure improves.

[0141] The Mo-Cu spacer according to the prior art is a metalworking material that substantially does not contain pores inside and has a porosity of approximately 0%, thereby exhibiting high thermal stress and low thermal fatigue fracture characteristics. In contrast, the copper structural plug according to the present invention comprises a lower layer having a high porosity, thereby providing low thermal stress and improved resistance to thermal fatigue fracture, and further comprises an upper layer having a low porosity, thereby preventing bonding defects in power semiconductor devices.

[0142] Additionally, the microstructural description for the first copper structure plug (140) can be equally applied to the second copper structure plug (150) and the third copper structure plug (160).

[0143] FIGS. 9A and 9B are cross-sectional views illustrating a pyramid-shaped copper structure plug of a ceramic circuit board according to one embodiment of the present invention.

[0144] Referring to FIG. 9a, the first copper structure plug (140) may have a truncated pyramid shape in which the planar area of ​​the upper side is smaller than that of the lower side as the planar area decreases from the lower side relatively adjacent to the second base copper layer (124) toward the upper side. That is, the first copper structure plug (140) may have a trapezoidal vertical cross-sectional shape. In addition, the first copper structure plug (140) may have a horizontal cross-sectional shape that is a polygon such as a triangle, a square, a pentagon, a hexagon, or a circle such as a square, an ellipse, a semicircle, or the like.

[0145] Since the first copper structure plug (140) has a pyramidal shape, it can be stably connected to a power semiconductor element. In addition, it can prevent an undercut phenomenon formed by etching.

[0146] These pyramidal shapes can be formed as follows.

[0147] After printing and pressing the first layer (151_1) of the first base portion (141) and then sintering, it can naturally shrink due to volume reduction caused by evaporation of the solvent and sintering of the copper particles. At this time, the lower side of the first layer (151_1) is attached to the second base copper layer (124), so the shrinkage is small, whereas the upper side shrinks greatly. Then, when the second layer (151_2) is printed, the area of ​​the lower side of the second layer (150_2) is reduced corresponding to the area of ​​the shrunken upper side. When the second layer (151_2) is sintered, the upper side shrinks more than the lower side, similar to the first layer (150_1). In this manner, a plurality of layers having an upper side having a smaller area than the lower side are formed. Next, a first surface portion (142) having an upper side having a smaller area than a lower side is formed on the n-th layer (150_n). Accordingly, a first copper structure plug (140) having a pyramidal shape can be formed.

[0148] In addition, in the step of forming the first copper structure plug (140), the application area of ​​the paste applied during printing can be reduced from the bottom to the top using TPC technology to implement the pyramidal shape. When forming a subsequent layer based on the first layer formed first, for example, a second layer (151_2) based on the first layer (151_1), the application area can be reduced to 1 area% to 10 area%, for example, 3 area% to 5 area%.

[0149] Additionally, similar to the first copper structure plug (140), the second copper structure plug (150) and the third copper structure plug (160) may have a pyramidal shape whose planar area decreases from the lower side relatively adjacent to the second base copper layer (124) toward the upper side.

[0150] Referring to Fig. 9b, photographs of a copper structure in the shape of a pyramid are shown.

[0151] Hereinafter, a method for manufacturing a wireless double-sided cooling power module according to one embodiment of the present invention will be described.

[0152] FIG. 10 is a flowchart illustrating a method for manufacturing a wireless double-sided cooling power module according to one embodiment of the present invention.

[0153] Referring to FIG. 10, the method for manufacturing the wireless double-sided cooling power module (S100) includes the steps of providing a first ceramic substrate (S110); providing a second ceramic substrate (S120); mounting a power semiconductor element on the first ceramic substrate (S130); forming a copper structure plug on the second ceramic substrate (S140); connecting a lead frame to the first ceramic substrate (S150); bonding the power semiconductor element and the copper structure plug (S160); and forming a mold layer filling a space between the first ceramic substrate and the second ceramic substrate (S170).

[0154] The step (S110) of providing the first ceramic substrate may be performed by providing a first ceramic substrate including a first ceramic layer, a first base copper layer disposed on a first surface of the first ceramic layer, and a first outer copper layer disposed on a second surface of the first ceramic layer opposite to the first surface.

[0155] In the step (S110) of providing the first ceramic substrate, the first base copper layer may be a TPC copper layer, a DBC copper layer, a DPC copper layer, or an AMB copper layer. The first outer copper layer may be formed using the same method as the method for forming the first base copper layer described above, and may be formed simultaneously with the first base copper layer.

[0156] The step (S120) of providing the second ceramic substrate may be performed by providing a second ceramic substrate that is disposed facing the first ceramic substrate and includes a second ceramic layer, a second base copper layer disposed on a third surface of the second ceramic layer, and a second outer copper layer disposed on a fourth surface of the second ceramic layer opposite to the third surface.

[0157] In the step (S120) of providing the second ceramic substrate, the second base copper layer may be a TPC copper layer, a DBC copper layer, a DPC copper layer, or an AMB copper layer. The second outer copper layer may be formed using the same method as the method for forming the second base copper layer described above, and may be formed simultaneously with the second base copper layer.

[0158] The step (S130) of mounting the power semiconductor element may be performed by mounting a power semiconductor element including a first electrode, a second electrode, and a third electrode on the first base copper layer of the first ceramic substrate. The power semiconductor element may be mounted by attaching it to the first ceramic substrate using a conductive adhesive, a conductive solder layer, or the like.

[0159] The step (S140) of forming the copper structure plug may be performed by forming the copper structure plug by printing, pressing, and sintering a copper-containing paste on the second base copper layer of the second ceramic substrate, so as to be disposed between the second ceramic substrate and the power semiconductor element and electrically connected to the power semiconductor element.

[0160] The step (S140) of forming the copper structure plug may include a printing step of forming a paste layer by printing a copper-containing paste on a portion of the second base copper layer; a pressing step of pressing the paste layer; and a sintering step of forming the copper structure plug by sintering the paste layer.

[0161] In the above printing step, a copper-containing paste may be screen-printed onto the second base copper layer to form a paste layer. The printing step may include a drying step that is intentionally performed to remove all or part of the solvent contained in the paste layer by maintaining the temperature in the air at a range of 10°C to 100°C. Alternatively, the drying may be performed unintentionally through natural drying.

[0162] In the above pressing step, the paste layer can be pressed to form a uniform thickness. The boundary of the paste layer may have a higher viscosity than the center due to a reduced flow rate of the copper-containing paste, and may be formed to a thicker thickness. By pressing the paste layer, this thickness variation can be reduced. In addition, internal pores in the paste layer can be eliminated or reduced.

[0163] In the above sintering step, the copper particles contained in the paste layer can be sintered. The sintering step can be performed in an inert atmosphere, such as a nitrogen atmosphere or an argon atmosphere, or can be performed in an air atmosphere. The sintering step can be performed in a continuous heat treatment furnace, such as a muffle-type heat treatment furnace, or in a batch-type heat treatment furnace, such as a box oven.

[0164] The sintering step may be performed at a temperature of, for example, less than 900°C, and may be performed at a temperature in the range of, for example, 500°C to 800°C for 10 to 120 minutes.

[0165] For example, when the second ceramic substrate includes an active metal brazing layer, it is important to prevent the active metal brazing layer from melting during the sintering step of forming the copper structure plug, and therefore, the sintering temperature is preferably lower than the melting temperature of the active metal brazing layer, and is preferably lower, for example, in the range of 50°C to 100°C.

[0166] In addition, the sintering may be performed by including a bake out step at a temperature ranging from 300°C to 500°C by supplying a small amount of water vapor or oxygen in a nitrogen atmosphere to remove the binder contained in the paste layer, and a liquid phase sintering step of the copper particles contained in the paste layer. However, this is exemplary and the technical idea of ​​the present invention is not limited thereto, and the bake out step may be omitted.

[0167] The step (S140) of forming the copper structure plug may be performed so that the copper structure plug has a differential porosity. The copper structure plug may include a region on the upper side having a lower porosity than a region on the lower side that is relatively adjacent to the second base copper layer.

[0168] The step (S140) of forming the copper structure plug may include: forming a base portion; and forming a surface portion on the base portion, the surface portion having a lower porosity than the base portion. The step of forming the base portion may be performed using a paste including copper particles having an average particle diameter in a range of more than 3 μm and less than or equal to 10 μm. The step of forming the surface portion may be performed using a paste including copper particles having an average particle diameter in a range of 100 nm to 3 μm on the base portion. The base portion may have a porosity in a range of more than 5 vol% and less than or equal to 20 vol%. The surface portion may have a porosity in a range of more than 0 vol% and less than or equal to 5 vol%.

[0169] The printing step, the pressing step, and the sintering step for forming the copper structure plug may be performed repeatedly. For example, after the printing step and the pressing step are performed in one cycle to form one paste layer, the printing step and the pressing step are performed again to further form a subsequent paste layer on the previously formed paste layer, thereby forming a plurality of paste layers. The plurality of paste layers may be sintered together. In addition, by repeatedly performing the sintering step, the copper structure plug may be formed. That is, the sintering step may be performed one or more times for one copper layer constituting the copper structure plug. The number of times of the printing step, the pressing step, and the sintering step may be varied.

[0170] In addition, if a paste layer is formed on only one side of the ceramic layer and sintered, the ceramic layer may warp during sintering. To prevent this, paste layers may be formed on both sides of the ceramic layer and sintered together to form the first base copper layer and the first outer copper layer simultaneously. In addition, the second base copper layer and the second outer copper layer may be formed simultaneously in the same manner. The copper structure plug may be additionally formed simultaneously with the second base copper layer and the second outer copper layer. It is preferable that the paste layers formed on both sides of the ceramic layer and sintered simultaneously have the same volume, or the volume ratio may be, for example, 90% to 100%. The volume ratio may be a percentage obtained by dividing the volume of the paste layer having a small volume by the volume of the paste layer having a large volume. In addition, the volume may be calculated from the weight of the paste layer.

[0171] In the step (S140) of forming the above copper structure plug, when performing the printing step, the application area of ​​the copper-containing paste is reduced from the lower side relatively adjacent to the second base copper layer toward the upper side, thereby allowing the copper structure plug to have a pyramidal shape.

[0172] The above copper structure plug may include a first copper structure plug, a second copper structure plug, and a third copper structure plug. The first copper structure plug, the second copper structure plug, and the third copper structure plug may be formed simultaneously in the same process.

[0173] The third copper structure plug may have a longer length than the first copper structure plug and the second copper structure plug, and for this purpose, printing, drying, and pressing steps for forming the third copper structure plug may be further performed. The sintering steps of the first copper structure plug, the second copper structure plug, and the third copper structure plug may be performed simultaneously.

[0174] The first copper structure plug may be formed to electrically connect the second base copper layer of the second ceramic substrate and the first electrode of the power semiconductor element.

[0175] The second copper structure plug may be formed to electrically connect the second base copper layer of the second ceramic substrate and the second electrode of the power semiconductor element.

[0176] The third copper structure plug may be formed to electrically connect the first base copper layer of the first ceramic substrate and the second base copper layer of the second ceramic substrate.

[0177] A blasting treatment may further be performed on the surface of at least one of the base copper layer, the outer copper layer, and the copper structure plug by blasting with ceramic particles such as sand.

[0178] Solder is applied on the base copper layer and a power semiconductor device is mounted. The copper structure plug is electrically connected to the power semiconductor device. The process of sintering the base copper layer and the copper structure plug is heat-treated at a high temperature in the air, so a copper oxide layer may be formed on the surface. In addition, oxidation by oxygen may occur even when the sintering is performed in an inert atmosphere. The copper oxide layer may reduce the adhesion of the power semiconductor device to the base copper layer and may deteriorate the electrical connection of the power semiconductor device to the copper structure plug. After forming the base copper layer, the outer copper layer, and the copper structure plug, the copper oxide layer may be removed by blasting fine-diameter ceramic particles onto the surfaces of each of the base copper layer, the outer copper layer, and the copper structure plug. The blasting may be referred to as sandblasting.

[0179] The step (S150) of connecting a lead frame to the first ceramic substrate may be performed by connecting the first base copper layer of the first ceramic substrate and the lead frame. The connection may be performed using a conductive adhesive, a conductive solder layer, or the like. The step (S150) of connecting the lead frame is optional and may be omitted.

[0180] The step (S160) of bonding the power semiconductor element and the copper structure plug is performed by placing the first ceramic substrate and the second ceramic substrate so as to face each other, and bonding the power semiconductor element and the copper structure plug. Specifically, the first copper structure plug and the first electrode of the power semiconductor element can be bonded. The second copper structure plug and the second electrode of the power semiconductor element can be bonded. The third copper structure plug and the first base copper layer of the first ceramic substrate can be bonded. The bonding can be performed using a conductive adhesive, a conductive solder layer, or the like.

[0181] The step of forming the mold layer (S170) may be performed by injecting a mold material into the space between the first ceramic substrate and the second ceramic substrate and solidifying the mold material, thereby forming a mold layer that fills the space. The power semiconductor element may be covered by the mold layer.

[0182] Accordingly, a wireless double-sided cooling power module according to one embodiment of the present invention can be completed.

[0183] Fig. 11 is an ultrasonic inspection result showing whether a defect occurs according to the sintering temperature of a ceramic substrate included in a wireless double-sided cooling power module according to an embodiment of the present invention.

[0184] Referring to Fig. 11, when the sintering of the base copper layer and the copper structure plug was performed at 900°C to form a ceramic circuit board, an adhesion defect occurred between the ceramic layer and the base copper layer, as indicated by an arrow. It is analyzed that the adhesion defect occurred due to exposure to a high temperature of 900°C during the sintering process of the base copper layer and the copper structure plug, and the occurrence became more pronounced as this high-temperature exposure was repeated. In particular, when the ceramic circuit board includes an active metal brazing layer, since the sintering temperature of 900°C approaches or exceeds the melting point of the active metal brazing layer, the adhesion defect occurs more as the active metal brazing layer melts.

[0185] On the other hand, when the sintering of the base copper layer and the copper structure plug was performed at 600°C, the adhesion defect did not occur. Therefore, the sintering temperature of the base copper layer and the copper structure plug is preferably lower than 900°C, and for example, a temperature in the range of 500°C to 800°C is preferable.

[0186] FIG. 12 is a photograph showing the surface condition of a ceramic substrate included in a wireless double-sided cooling power module according to one embodiment of the present invention before and after blasting treatment.

[0187] Referring to Fig. 12, the surface condition of the base copper layer before and after blasting treatment is shown. When blasting treatment is not performed, it can be seen that copper oxide exists on the surface of the base copper layer and the surface is rough. On the other hand, it can be seen that the copper oxide is removed by blasting treatment, resulting in a smooth surface, and that the surface becomes smoother as the number of blasting cycles increases. Therefore, after blasting treatment, the power semiconductor device mounted on the base copper layer can be more stably bonded.

[0188] It will be apparent to a person skilled in the art to which the technical idea of ​​the present invention pertains that the technical idea of ​​the present invention described above is not limited to the above-described embodiments and the attached drawings, and that various substitutions, modifications, and changes are possible within a scope that does not depart from the technical idea of ​​the present invention.

Claims

1. A first ceramic substrate comprising a first ceramic layer and a first base copper layer disposed on a first surface of the first ceramic layer; A second ceramic substrate disposed facing the first ceramic substrate, the second ceramic substrate including a second ceramic layer and a second base copper layer disposed on a third surface of the second ceramic layer; A semiconductor element mounted on the first ceramic substrate and including a first electrode, a second electrode, and a third electrode; and A copper structure plug disposed between the second ceramic substrate and the semiconductor element, electrically connected to the semiconductor element, and formed by printing, pressing, and sintering a copper-containing paste, Wireless double-sided cooled power module.

2. In paragraph 1, The above copper structure plug, A first copper structure plug electrically connecting the first electrode of the semiconductor element to the second base copper layer of the second ceramic substrate; and A second copper structure plug electrically connecting the second electrode of the semiconductor element to the second base copper layer of the second ceramic substrate. Wireless double-sided cooled power module.

3. In paragraph 2, The above copper structure plug, Further comprising a third copper structure plug disposed between the first base copper layer of the first ceramic substrate and the second base copper layer of the second ceramic substrate, electrically connecting the first base copper layer and the second base copper layer. Wireless double-sided cooled power module.

4. In paragraph 1, The third electrode of the above semiconductor device is, Electrically connected to the first base copper layer of the first ceramic substrate, Wireless double-sided cooled power module.

5. In paragraph 1, The above copper structure plug, having a differential porosity, and including a region on the upper side having a lower porosity than the lower side relatively adjacent to the second base copper layer, Ceramic circuit board.

6. In paragraph 1, The above copper structure plug, The porosity decreases from the lower side relatively adjacent to the second base copper layer toward the upper side, Ceramic circuit board.

7. In paragraph 1, The above copper structure plug, Having a pyramidal shape whose plane area decreases from the lower side to the upper side relatively adjacent to the second base copper layer, Wireless double-sided cooled power module.

8. In paragraph 1, The above copper structure plug, Base; and A surface portion disposed on the base portion and having a lower porosity than the base portion, Ceramic circuit board.

9. In paragraph 8, The above base has a porosity in the range of more than 5% by volume and less than 20% by volume, The above surface portion has a porosity in the range of more than 0 volume% and less than 5 volume%, Ceramic circuit board.

10. In paragraph 1, Further comprising a lead frame electrically connected to the first base copper layer of the first ceramic substrate, Wireless double-sided cooled power module.

11. In paragraph 1, Further comprising a mold layer filling the space between the first ceramic substrate and the second ceramic substrate, Wireless double-sided cooled power module.

12. In paragraph 1, The first ceramic substrate further includes a first outer copper layer disposed on a second surface opposite to the first surface, The second ceramic substrate further includes a second outer copper layer disposed on a fourth surface opposite to the third surface. Wireless double-sided cooled power module.

13. In paragraph 1, At least one of the first base copper layer and the second base copper layer, A TPC copper layer formed by printing, pressing and sintering a copper-containing paste on the above ceramic layer, A DBC copper layer formed by bonding copper foil on the above ceramic layer through a high-temperature oxidation process, After forming a seed layer on the above ceramic layer, a DPC copper layer formed by plating copper on the seed layer, Or, it is made of an AMB copper layer formed by a copper foil bonded using an active metal foil to the above ceramic layer. Wireless double-sided cooled power module.

14. In paragraph 1, At least one of the first base copper layer and the second base copper layer, Comprising at least one of a bonding copper layer, a laminated copper layer, and a surface copper layer, Wireless double-sided cooled power module.

15. In paragraph 14, The above bonding copper layer is formed using a copper-containing bonding paste including glass frit, inorganic particles, copper oxide particles, copper particles, a solvent, and a binder, The above laminated copper layer is formed using a copper-containing laminate paste including inorganic particles, copper particles, a solvent, and a binder, The above surface copper layer is formed using a copper-containing surface paste containing copper oxide particles, copper particles, a solvent, and a binder. Wireless double-sided cooled power module.

16. A step of providing a first ceramic substrate including a first ceramic layer and a first base copper layer disposed on a first surface of the first ceramic layer; A step of providing a second ceramic substrate, which is disposed facing the first ceramic substrate and includes a second ceramic layer and a second base copper layer disposed on a third surface of the second ceramic layer; A step of mounting a semiconductor element on the first ceramic substrate; A step of forming a copper structure plug by printing, pressing, and sintering a copper-containing paste at a temperature ranging from 500°C to 700°C on the second base copper layer of the second ceramic substrate; and A step of arranging the first ceramic substrate and the second ceramic substrate so as to face each other, and bonding the semiconductor element and the copper structure plug, A method for manufacturing a wireless double-sided cooling power module.

17. In paragraph 16, The step of forming the above copper structure plug is: The copper structure plug is performed so that it has a differential porosity and includes a region on the upper side having a lower porosity than the lower side relatively adjacent to the second base copper layer. A method for manufacturing a wireless double-sided cooling power module.

18. In paragraph 16, In the step of forming the above copper structure plug, After forming one paste layer in one cycle by performing the above printing step and the above pressing step, the printing step and the above pressing step are performed again to form a subsequent paste layer on the previously formed paste layer, thereby forming a plurality of paste layers, and sintering the plurality of paste layers together. A method for manufacturing a wireless double-sided cooling power module.

19. In paragraph 16, In the step of forming the above copper structure plug, When performing the above printing step, the copper structure plug has a pyramidal shape by reducing the application area of ​​the copper paste from the lower side to the upper side adjacent to the second base copper layer. A method for manufacturing a wireless double-sided cooling power module.

20. In paragraph 16, The first ceramic substrate includes a first active metal brazing layer interposed between the first ceramic layer and the first base copper layer, The second ceramic substrate includes a second active metal brazing layer interposed between the second ceramic layer and the second base copper layer. A method for manufacturing a wireless double-sided cooling power module.

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