TWI778499B - Power module with chamfered metal spacer unit - Google Patents

Abstract

A power module with a metal spacer unit with a lead angle, between a power element and an upper substrate, a space with the same height as the metal spacer unit is formed through a metal spacer unit with a fixed height and a lead angle, and a space with the same height as the metal spacer unit is exposed. The control substrate for the wire bonding process and the gap for the glue filling process. This space can accommodate the working tools of the wire bonding and glue filling process, improve the operating angle of the tools, so that the wire bonding and glue filling process can be performed more efficiently, and the yield of the production line can be increased.

Description

Power module with chamfered metal spacer unit

A power supply module, especially a high thermal conductivity power supply module with lead-angled metal spacer units.

In today's increasingly serious global warming, with the rising awareness of environmental protection, governments around the world have also introduced many green energy subsidy policies in transportation in recent years, making more and more consumers choose electric vehicles to replace the traditional fossil fuels. Powered vehicles, such as replacing conventional cars with electric vehicles and replacing two-stroke locomotives with electric scooters. These electric vehicles all rely on high-power electric motors to provide power. Therefore, the market demand for high-power power modules has grown, and major suppliers have also rushed to invest in capital and research and development to improve production line yield and output. In addition, light source devices such as high-brightness LEDs or LDs are constantly being introduced, resulting in a continuous increase in the energy consumption of the power supply devices. Power modules with high power and high heat dissipation are also required for effective support.

Due to the high energy consumption of high-power power modules, a part of the energy will inevitably be converted into heat energy; at the same time as the miniaturization of electronic devices, high-power components will be accompanied by higher heat in a smaller space, so How to remove excess heat energy and maintain the stability of the operating environment becomes critical. In order to solve the problem of heat dissipation, the commonly adopted solution is to use ceramic material as the insulating material layer of the circuit substrate. As a kind of circuit board, the ceramic substrate has a thermal expansion coefficient close to that of a semiconductor and high heat resistance. Most common ceramic materials There is a Direct Bonded Copper (DBC) substrate made of aluminum oxide (Aluminum Oxide, Al2O3). Among them, the thermal conductivity of aluminum oxide can reach 35W/mK under the single crystal structure, and 20 to 27W under the polycrystalline structure. /mK. Other common ceramic substrates include aluminum nitride (AlN), beryllium oxide (BeO), and silicon carbide (SiC). Therefore, ceramic substrates have become the first choice for high-power power module substrates.

In the selection of high-power electronic components for power modules, in addition to silicon, the most commonly used material for electronic components, high-power components of silicon carbide (SiC) and gallium nitride (GaN) are gradually gaining a place in the market. . Such components have higher efficiency and operating temperature, which are extremely important performance indicators especially in power modules that conduct large currents. Compared with silicon, SiC has 10 times the insulation breakdown electric field strength, 3 times the energy band gap width and 3 times the thermal conductivity, which enables the above electronic components to be fabricated with a very thin drift layer with a very high breakdown voltage (above 600V). ) components, and the resistance per unit area can be reduced to 1/300 of that of silicon under the same breakdown voltage. SiC power components can operate at higher temperatures, and the thermal conductivity is three times that of silicon, which helps reduce heat dissipation requirements, so SiC high-power electronic components are the development trend for power modules.

As shown in FIG. 1 , a high-power electronic component exemplified as a power module chip 90 needs to be switched between two states of conducting high current and disconnecting. In order to avoid direct short circuit of high current, a pair of input and output electrodes 92 and 94 are usually distributed in, for example, On both sides of the top and bottom of the SiC, and the inlet and outlet electrodes 92 and 94 at the top and the bottom are respectively electrically and thermally connected to the two corresponding ceramic substrates 82 and 84, so that the power module wafer 90 and the ceramic substrates 82 and 84 form a similar The structure of the sandwich. Therefore, the high-power electronic components are sandwiched between the ceramic substrates, especially the distance between the two ceramic substrates 82 and 84 in the height direction is only hundreds of microns, which is very narrow; and in order to control the conduction or disconnection of the electronic components, a For a control electrode 96, as shown in Figures 2 and 3, because the surface space of high-power electronic components is limited, only an insulating gap 98 of several tens of microns is usually reserved between the control electrode and the input and output electrodes.

The control electrode 96 of the power module chip needs to receive control signals and effectively control the flow and disconnection of large currents. Therefore, the control electrode 96 and the input and output electrodes 92 that flow through when the current is turned on must not be connected, and there are only the above-mentioned tens of microns between them. Gap 98, but it is necessary to ensure that when a large current flows between the two incoming and outgoing electrodes, it will not mistakenly flow through the control electrode 96 to cause a short circuit, so as to protect the control electrode 96 from overheating and melting. The gap between the aforesaid control electrode 96 and the pads of the input and output electrodes 92 and 94 must be well insulated, so that no flashover will occur due to instantaneous current changes at the moment of connection or disconnection. The glue process isolates the electrodes, pours non-conductive viscous polymer materials, and maintains insulation after curing; the control electrodes 96 are connected to an external control circuit (not shown) through wire bonding.

In order to accommodate the rising space of the wire bonding wire after the first welding, and to enable the glue filling process to perform the glue filling operation more accurately to prevent overflow, if the gap between the ceramic substrates is too small, it will hinder the filling process. The glue and wire bonding process is carried out, or the glue filling or wire bonding process must be carried out at an inclination angle, resulting in prolonged operation time or reduced yield. How to ensure that the high-power electronic components can conduct heat dissipation between the two ceramic substrates as expected, and at the same time improve the operation angle and yield of the glue filling and wire bonding processes in the narrow gap, which is the purpose of this case.

Further, when the present invention additionally sets a metal spacer unit on the top surface of the power module chip, thereby pulling the height between the upper ceramic substrate and the power supply chip module apart, so that the insulating gap is exposed, because the metal spacer unit There is a considerable difference in the thermal expansion coefficient between the power module chip and the power module chip. Whether it is in the process of installation or operation, it will face a high temperature of more than 200 degrees Celsius. During the operation of repeated temperature fluctuations, the metal spacer unit and the power module chip are connected. The interface will start to peel off from the corner due to stress concentration. In order to avoid this problem, the present invention further forms chamfers at the corners of the metal spacer unit, so as to avoid concentrated peeling of the reflection force with a sharply protruding right angle.

An object of the present invention is to provide a power module with a metal spacer with a chamfered angle, which can improve the operation angle and yield of the narrow gap between the pads in the gluing process while maintaining a good heat dissipation effect.

Another object of the present invention is to provide a power supply module with metal spacer units, which can maintain good heat dissipation, ensure the required operating height of the first solder joint in the wire bonding process, and improve the operating angle and yield of the wire bonding process.

Another object of the present invention is to provide a power supply module with metal spacer units with chamfered angles, so that there is no right-angled protrusion at the interface between the metal spacer unit and the ceramic substrate, thereby greatly reducing the problem of stress concentration and avoiding the interface at the corners. peel off.

In order to achieve the above object, the present invention discloses a power module with chamfered metal spacer units, comprising: a first substrate including at least one mounting ceramic substrate portion with a predetermined length and width, and the first substrate has a setting surface, and a mounting circuit layer formed on the setting surface; at least one power component, the power component has a pair of input and output electrodes located on a top surface and a bottom surface respectively, and a control electrode located on the top surface, the power component The input and output electrodes on the bottom surface are electrically connected to the mounting circuit layer of the mounting ceramic substrate, and an insulating gap is formed between the input and output electrodes on the top surface and the control electrode; the number corresponds to the metal spacer unit of the power element. , each of the above-mentioned metal spacer units is respectively thermally and electrically conductively disposed on the above-mentioned top surface in-out electrodes of the above-mentioned corresponding power components, and the above-mentioned metal spacer units have a predetermined height, and each of the above-mentioned metal spacer units respectively forms a lead angle at each corner , thereby forming a projection not exceeding the top surface in-out electrodes in the direction of the aforementioned height; and a second base parallel to the first substrate and comprising at least one spaced ceramic substrate portion with a predetermined length and width board, and the second substrate has a corresponding surface, and a spacer circuit layer formed on the corresponding surface, the second substrate is electrically and thermally bonded to the metal spacer unit by the spacer circuit layer of the spacer ceramic substrate portion. On the side surface of the power element, a space corresponding to the predetermined height is formed between the control electrode of the power element and the second substrate, and the insulating gap is exposed.

According to the present invention, between the second substrate and the top surface of the power element, a metal spacer unit is installed corresponding to each element, and the metal spacer unit has a predetermined height and forms chamfers at each corner respectively, so that the direction of the height is in the direction of the height. Form a projection that does not exceed the above-mentioned top surface entry and exit electrodes, so that the control electrode of the circuit element and the second substrate form an interval that can accommodate the rising space of the first soldering wire and expose the above-mentioned insulating gap, so that the glue filling process can be carried out more smoothly. Avoid overflow or Insufficient situation, improve yield, and due to the formation of the above-mentioned space, the operation angle of glue filling or wire bonding is less likely to be restricted; especially, the metal spacer units are formed with chamfers at the corners, which effectively reduces repeated thermal expansion. and shrinkage stress concentration during operation to avoid interface peeling.

1, 1': the first substrate

11, 11': set face

12, 12': Install the circuit layer

13': first dielectric material layer

14, 14': Install the ceramic substrate part

2, 2': power components

21, 21': bottom surface

211, 211', 221, 92, 94: In and out electrodes

22: Top surface

222, 222', 96: control electrode

223, 98: Insulation gap

224': wire

3, 3': metal spacer unit

4, 4': the second substrate

41, 41': Corresponding surface

42, 42': spacer circuit layer

43': second dielectric material layer

44, 44': Spacer ceramic substrate part

82, 84: Ceramic substrate

90: Power module chip

FIG. 1 is a schematic perspective view of a high-power module of the prior art.

FIG. 2 is a schematic side view of a high-power module of the prior art.

FIG. 3 is a schematic front view of a high-power module of the prior art.

4 is a three-dimensional schematic view of the first preferred embodiment of the power module of the present invention after the second substrate is removed, illustrating the relative structural relationship of the metal spacer unit to expose the insulating gap.

FIG. 5 is a perspective view of a first preferred embodiment of the power module of the present invention.

FIG. 6 is a schematic front view of the first preferred embodiment of the power module of the present invention.

FIG. 7 is a schematic side view of the first preferred embodiment of the power module of the present invention.

FIG. 8 is a perspective view of a second preferred embodiment of the power module of the present invention.

9 is a schematic side view of a second preferred embodiment of the power module of the present invention.

The foregoing and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of the preferred embodiments with reference to the drawings; in addition, in each embodiment, the same elements will be represented by similar label representation.

A first preferred embodiment of a power supply module having a metal spacer with a lead angle of the present invention is shown in FIGS. 4 to 7 . The first substrate 1 includes a high thermal conductivity ceramic substrate made of, for example, aluminum nitride. This is defined as the mounting ceramic substrate portion 14 and the mounting circuit layer 12 above the mounting ceramic substrate portion 14 . For convenience of description, the top surface of the mounting ceramic substrate portion 14 with the mounting circuit layer 12 is defined as the mounting surface 11 . The mounting circuit layer 12 is for mounting the power element 2 with an operating current of more than tens of amperes, and the direction of the thickness of the first substrate 1 is defined as the height direction.

In this example, copper metal layers are formed on the entire surface of the installation surface 11 and the bottom surface opposite to the installation surface 11 by, for example, sputtering, and then photolithography is used to remove parts of the installation surface 11 that do not require conduction. The circuit layer 12 is installed, both of which may be thickened by electroplating or the like as necessary. Of course, those skilled in the art can also use similar methods other than sputtering to form the circuit layer.

Next, the bottom surface 21 of at least one power element 2 is firmly welded on the mounting circuit layer 12 , and the power element 2 is exemplified as a 1200V SiC power chip of STMicroelectronics in this example; the above-mentioned power element 2 includes one a bottom surface 21, an input and output electrode 211 on the bottom surface 21 soldered on the mounting circuit layer 12, a top surface 22, an input and output electrode 221 on the top surface 22, a control electrode 222 on the top surface 22 and separated from the input and output electrodes 221, An insulating gap 223 is formed between the access electrode 221 and the control electrode 222 . Since the current of such power components can even reach hundreds of amps, once there is a little resistance in the transmission path, it will cause great heat. Therefore, the welding in this example is achieved by pressure and heat fusion.

Next, a metal spacer unit 3 exemplified by copper is welded to the input and output electrodes 221 of the top surface 22 of the power element 2 after the surface is subjected to a nano-silver sintering process. The projection of the metal spacer unit 3 in the height direction does not exceed the inlet and outlet electrodes 221 of the top surface 22 of the power element 2, thereby forming a predetermined height between 400 and 1000 μm above the control electrode 222 and the insulating gap 223 on the top surface 22 of the power element 2 The space between them ensures that the control electrodes 222 and the insulating gaps 223 which are also located on the top surface 22 are respectively exposed, thereby allowing the control electrodes 222 to be connected to external control circuits by wire bonding. Especially in this example, the corners of the metal spacer unit 3 are formed with, for example, arc-shaped chamfers, so that whether it is the heating during welding or the temperature rise caused by the passage of a large current during operation, and the repeated temperature difference when the temperature decreases. , the inter-interface stress caused by thermal expansion and cooling contraction can be effectively dispersed by the arc-shaped chamfer, thereby avoiding interface peeling caused by thermal stress.

The second substrate 4 also includes a ceramic substrate corresponding to the mounting ceramic substrate portion 14 , which is defined as a spacer ceramic substrate portion 44 , and a spacer circuit layer 42 of copper metal is formed on the corresponding surface 41 of the corresponding metal spacer unit 3 . , the spacer circuit layer 42 is soldered to the metal spacer unit 3 . Therefore, in the height direction, between the spacer circuit layer 42 and the control electrode 222 of the top surface 22 of the power element 2 and the insulating gap 223, a space equal to the height of the metal spacer unit 3, eg, 400 to 1000 μm, is formed. Since the height of the interval is at least 400 μm, it is larger than 200~300 of the above-mentioned wire diameter. μm, so as to ensure that the wires connected by wire bonding before will not be damaged by pressing; on the other hand, a non-conductive viscous polymer material should be poured into the insulating gap 223 and kept insulated after curing, thereby isolating Two electrodes can also greatly improve the problem in the prior art, because the gap of the glue filling is only a closed narrow channel, and it is difficult to ensure that the insulating resin material can fill the gap, so that the insulating ability of the manufactured product cannot be guaranteed.

Even if the control electrodes 222 are connected by wires after the second substrate 4 is installed, the metal spacer unit 3 pulls the power element 2 and the second substrate 4 apart in the height direction, so that the wire bonding operation can still be successfully completed. Therefore, by the disclosure of the present invention, the wire bonding and gluing processes can be performed more efficiently, which not only improves the manufacturing yield, but also simultaneously increases the output efficiency, greatly reduces the assembly cost of the power device, and improves the market competitiveness.

Please refer to FIGS. 8 and 9 , the second preferred embodiment of the power module of the present invention, in which the same parts as those of the previous preferred embodiment will not be repeated here, and similar components are also given similar names and labels, only the differences Provide an explanation. In this example, a power supply module that uses multiple power elements 2' in parallel is set at the same time, such as a power supply for an electric vehicle. The total current may be as high as several hundred amperes, so multiple power elements 2' need to be set. Among them, the first substrate 1' is mainly made of a circuit board of dielectric material, thereby separating thermoelectricity. At the circuit board of dielectric material, the circuit can be more complicated by the design of multi-layer boards, but in the corresponding power At the component 2', a plurality of corresponding through holes are formed in the first dielectric material layer 13', for the mounting ceramic substrate portion 14' to be embedded therein. The surface is flush, which is referred to as the setting surface 11 ′ here, and a mounting circuit layer 12 ′ is formed on the setting surface 11 ′, thereby forming a thermoelectrically separated integrated circuit board.

Next, as described above, the bottom surfaces 21' of the three power elements 2' in the figure are respectively welded to the input and output electrodes 211' on the mounting circuit layer 12', and the projection range of the power element 2' in the height direction is within the range where the ceramic substrate portion 14' is mounted.

Similarly, in this example, the second substrate 4' is also correspondingly embedded with a spacer ceramic substrate portion 44' in the second dielectric material layer 43', and also on the flush corresponding surface 41', a corresponding metal is formed. The spacer unit 3' corresponds to the spacer circuit layer 42', whereby the spacer ceramic substrate portion 44' is welded to the metal spacer unit 3' through the spacer circuit layer 42'.

In order to avoid cracks caused by thermal expansion and contraction caused by the difference in thermal conductivity between the metal spacer unit 3 ′, the spacer ceramic substrate portion 44 ′ and the power element 2 ′, the side surface of the metal spacer unit 3 ′ in this example is stronger than the power element 2 ′. The corresponding side surfaces of the element 2' are inwardly shrunk, so that there is a stretch of space between the two, especially at the corners of the metal spacer unit 3', which respectively form arc-shaped chamfers, which serve as stress deformation during heating and cooling. buffer.

Since the first substrate and the second substrate in the power module of this example are both embedded with ceramic substrates using thermoelectrically separated dielectric materials, the better thermal conductivity of ceramics can be properly utilized in the high heat-generating part corresponding to the power element. The heat energy generated when the power element works is exported to, for example, a heat dissipation fin that is thermally connected to the ceramic substrate. The whole module can also use a multi-layer board in the dielectric material layer, and additionally set a more complicated control circuit, which is connected to the first dielectric material layer 13' through the bonding wire 224' electrically connected to the control electrode 222', allowing the control and operation is more versatile and can meet the needs of various situations.

To sum up, in the present invention, a space with the same height as the metal spacer is formed between the power element and the second substrate through a metal spacer unit with a fixed height and a chamfered angle, and a space for the wire bonding process is exposed. Controls the gap between the substrate and the potting process. This space can accommodate the working tools of the wire-bonding and glue-filling processes, improve the operating angle of the tools, so that the wire-bonding and glue-filling processes can be executed more efficiently, and effectively improve the production line yield and output efficiency; The above object of the present invention is achieved.

However, the above are only the preferred embodiments of the present invention, which cannot limit the scope of the present invention. Any simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the description of the invention should be It still falls within the scope of the patent of the present invention.

1: The first substrate

11: Set face

12: Install the circuit layer

14: Install the ceramic substrate part

2: Power components

21: Underside

211, 221: In and out electrodes

22: Top surface

222: Control Electrode

223: Insulation gap

3: Metal spacer unit

4: Second substrate

41: Corresponding surface

42: Spacer circuit layer

44: Spacer ceramic substrate part

Claims (7)

A power module with chamfered metal spacer units, comprising: a first substrate, comprising at least one mounting ceramic substrate portion with a predetermined length and width, and the first substrate has a setting surface and a mounting circuit layer formed on the setting surface; At least one power element, the power element has a pair of input and output electrodes respectively located on a top surface and a bottom surface, and a control electrode located on the top surface, the power element is conductively coupled to the mounting ceramic substrate portion with the input and output electrodes on the bottom surface The above-mentioned mounting circuit layer, and an insulating gap is formed between the above-mentioned input and output electrodes on the above-mentioned top surface and the control electrode; The number corresponds to the metal spacer units of the power element, each of the metal spacer units is thermally and electrically conductively disposed on the top surface in-out electrodes of the corresponding power element, and the metal spacer units have a predetermined height, and each of the metal spacers has a predetermined height. The spacer units respectively form lead angles at each corner, thereby forming a projection in the direction of the aforementioned height that does not exceed the above-mentioned top surface entry and exit electrodes; and a second substrate parallel to the first substrate and comprising at least one spaced ceramic substrate portion having a predetermined length and width, the second substrate has a corresponding surface, and a spaced circuit layer formed on the corresponding surface, The second substrate is electrically and thermally bonded to the other side of the metal spacer unit opposite to the power element by the spacer circuit layer of the spacer ceramic substrate portion, so that a correspondence is formed between the control electrode of the power element and the second substrate The above-mentioned predetermined height of the space and exposing the above-mentioned insulating gap. The power module with chamfered metal spacer units as described in claim 1, further comprising at least one heat dissipation device mounted on the mounting ceramic substrate portion and/or the spacer ceramic substrate portion in a direction away from the power element and thermally conductive fins. The power module with chamfered metal spacer units as described in claim 1, wherein the material of the metal spacer units is selected from the group consisting of copper, silver and aluminum. The power module with chamfered metal spacer units as described in claim 3, wherein the surfaces of the metal spacer units are plated with silver. The power module with chamfered metal spacer units as described in claim 1, wherein the power element is a power management integrated circuit. The power module with chamfered metal spacer units as described in claim 1, wherein the first substrate is a circuit substrate with an embedded ceramic substrate. The power module with chamfered metal spacer units as described in claim 1, wherein the second substrate is a circuit substrate with an embedded ceramic substrate.

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