TECHNICAL FIELD

The present disclosure relates to an electrical device, and particularly to a power module having features for clamping and a power module assembly and an electrical device comprising the power module.

BACKGROUND

The electrical and mechanical requirements of the customers for industrial and automotive application are increasing. Power modules are used in different kinds of electrical devices. The space for molded power modules in an electrical device, such as an inverter, is getting smaller and smaller.

Conventionally, power modules are fixed mounted on a substrate through fixing members, such as screws or bolts. Usually, fixing members need to pass through corresponding fixing parts of a power module to fix it onto the substrate. The fixing parts occupy spaces, such that more spaces are needed in the electrical device. Moreover, in case of a plurality of power modules are needed, these power modules cannot be arranged compactly due to the fixing parts.

One solution is shown in Figs. 1 and 2. A power module 100 comprises a base plate

110 and a molded body 120 provided on the base plate 100, sealing or encapsulating electronic components such as chips (not shown) arranged on the base plate 110. In order to fix the power module a substrate (not shown), fixing parts 130, which may be integrated with the base plate 110, are provided. Each of the fixing parts 130 may be provided with a hole, through which a fixing member 140 may pass. The fixing member 140 then may be fixed to the substrate so that the power module 100 may be fixed to the substrate.

To mount a plurality of power modules 100 compactly on the substrate, the fixing parts 130 are formed in a staggered arrangement along two sides of the base plate 110. In such a manner, when the plurality of power modules 100 are fixed on the substrate, fixing parts of one power module 100 may be arranged alternately with fixing parts of an adjacent power module 100, as shown in Fig. 2.

However, providing the fixing parts is a significant increase of cost of manufacturing the base plate and the power module. Further, each power module needs to be provided with several fixing parts to be securely mounted to the substrate, and therefore, mounting the power module is time consuming.

There is needed a solution, by which the power modules may be mounted

conveniently and compactly. SUMMARY

The present disclosure has been made to overcome or alleviate at least one aspect of the above mentioned disadvantages.

In one aspect of the disclosure, there is provided a power module.

In an exemplary embodiment, the power module may comprise: a base plate; an electronic component mounted on a top surface of the base plate; and a body

encapsulating the electronic component and the base plate. A part of the top surface of the base plate is externally accessible. By "externally accessible" is meant that the exposed part of the top surface of the base plate may be accessed from outside of the

aforementioned power module by another component or tool that is not part of the power module itself.

In another embodiment, the body may be molded on the base plate and provided with at least one opening in the body, such that the part of the top surface of the base plate is accessible from the opening.

In a further embodiment of the base plate may comprise a metal. Such metals such as copper, aluminium or stainless steel may be used, or mixtures or alloys of such metals. The advantages of a metal base plate include the ability to conduct heat rapidly from any electronic component mounted thereon to a cooler or heatsink. Additionally a metal base plate will form a stable, robust and stiff mounting place for electronic components that form part of the power module.

In a still further embodiment the body may completely encapsulates the electronic component and partially encapsulates the base plate. Such a form of the encapsulation is able to protect the electronic component from the negative consequences of the external environment such as humidity, corrosion and dust. The partial encapsulation of the base plate yields a stable and stiff encapsulation leading to increased stability and lifetime of the power module. The body may to advantage comprise a hard mold material. Such a hard mold material may comprise a plastic, epoxy, or polymer material which can be applied in liquid or two-part form and which will harden to form a solid mass.

In yet another embodiment, there may be no apertures extending from the exposed top surface of the base plate to the bottom surface of the base plate. Such apertures, in the form of a bolt hole for example, may be used in prior art modules for the insertion of a fixing device, such as a bolt, through the aperture and which fixing device is then used to apply pressure between the base plate and any substrate onto which the base plate is being fixed. In the current invention such apertures are not necessary, since it is possible to apply a clamp which exerts pressure on the top surface of the base plate within the opening in the body. Such a clamping method of fixing the base plate is a distinct advantage in the production of power module assemblies, since the assembly can be made faster since no bolts are needed to be fitted through bolt holes, and the use of clamps allows much closer assembly of separate power modules to form a power module assembly. This space-saving aspect can be critical in applications where volume is limited.

In a still further embodiment, the opening may comprise an indentation formed in an edge of body or a hole formed in the body.

In a still further embodiment, a plurality of the openings may be distributed symmetrically in the body.

In another aspect of the disclosure, there is provided a power module assembly.

In an exemplary embodiment, the power module assembly may comprise: at least one power module according to any one of the above embodiment; a substrate on which the power module is disposed; and at least one clamping device configured for clamping on the part of the top surface of the base plate and fixing the power module to the substrate.

In another embodiment, the body may be molded on the base plate and provided with at least one opening in the body, such that the part of the top surface of the base plate is accessible from the opening; and the clamping device may comprise a clamping member having a protrusion extending into the opening and clamped on the accessible part of the upper surface of the base plate.

In a further embodiment, the clamping device further comprises a fixing member configured for fixing the clamping member to the substrate.

In a still further embodiment, a plurality of the power modules are arranged side by side, and the clamping device is located between two adjacent power modules and clamped on the accessible parts of the two adjacent power modules.

In a still further embodiment, a plurality of the power modules are arranged into an array, the clamping device is located between two adjacent columns of the power modules, and wherein the clamping device extends along the two adjacent columns and is clamped on the accessible parts of the power modules in the two adjacent columns.

In a still further embodiment the fixing of the power modules to the substrate may be accomplished without the use of a clamping device which passes through an aperture in the baseplate. Such apertures, in the form of a bolt hole for example, may be used in prior art modules for the insertion of a fixing device, such as a bolt, through the aperture and which fixing device is then used to apply pressure between the base plate and any substrate onto which the base plate is being fixed. In the current invention such apertures are not necessary, as discussed above, since it is possible to apply a clamp which exerts pressure on the top surface of the base plate within the opening in the body. The advantages of such a system of also been discussed above.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present disclosure will become more apparent by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which:

Fig. 1 is an illustrative perspective view of an existing power module;

Fig. 2 is an illustrative perspective view, showing an arrangement of a plurality of power modules of Fig. 1;

Fig. 3 is an illustrative top view of a power module according to an embodiment of the present disclosure;

Fig. 4 is an illustrative enlarged cross-sectional view taken along the line A-A of Fig. 3; Fig. 5 is an illustrative top view, showing two power modules of Fig. 3 mounted side by side;

Fig. 6 is an illustrative cross-sectional view taken along the line B-B of Fig. 5;

Fig. 7 is an illustrative top view, showing four power modules arranged into an array according to an embodiment of the present disclosure;

Fig. 8 is an illustrative top view of a power module according to another embodiment of the present disclosure;

Fig. 9 is an illustrative top view of a power module according to still another embodiment of the present disclosure;

Fig. 10 is an illustrative cross-sectional view taken along the line C-C of Fig. 9;

Fig. 11 is an illustrative perspective view of the power module of Figs. 9 and 10, where a clamping member assembled with the power module is shown; and

Fig. 12 is an illustrative cross-sectional view taken along the line D-D of Fig. 11.

DETAILED DESCRIPTION OF EMBODIMENTS

Exemplary embodiments of the present disclosure will be described hereinafter in detail with reference to the attached drawings, wherein the like reference numerals refer to the like elements. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein; rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the concept of the disclosure to those skilled in the art.

Figs. 3 and 4 show a power module in an embodiment of the present disclosure. The power module 200 comprises abase plate 210, an electronic component 230 mounted on a top surface of the base plate 210 and a body 220 encapsulating the electronic component 230 and the base plate 210. As shown in Figs. 3 and 4, a part of the top surface of the base plate is exposed from the body 220 and thereby externally accessible. By the term

"externally accessible" is meant that the exposed part of the top surface of the base plate may be accessed from outside of the power module 200 by another component or tool that is not part of the power module itself. Using this feature, a clamping device, which will be described in detail hereinafter, can be utilized to clamp on the exposed or accessible part of the top surface of the base plate 200, and the power module 200 can thereby be fixedly mounted to a substrate 400 (Fig. 6), a cooler, a circuit board or other mounting surface.

To expose the part of the top surface of the base plate 200, the body, which is usually molded on the base plate and encapsulates the top surface and side surface of the base plate, can be provided with at least one opening 221, such that the part of the top surface of the base plate is accessible from the opening 221.

The opening 221 may be in form of an indentation 2211 formed in an edge of body 220. In another embodiment, the opening 221 may be in form of a hole 2212 formed in the body 220, which will be described in detail hereinafter. It can be anticipated by an ordinary skilled person that the indentation or hole may be formed while the body is being molded on the base plate. Therefore, an appropriate mold could be used to form the molded body having the indentation or hole. It can be understood that there may be one or more indentations 2211 formed in the body, depending on practical situations or requirements. In the embodiment shown in Figs. 3 and 4, four indentations 2211 are provided, two of the indentations 2211 are formed in one side or edge of the body 220, and the other two of the indentations 2211 are formed in an opposite side or edge of the body 220. The four indentations 2211 are formed symmetrically in the two opposite sides of the body 220. In another embodiment shown in Fig. 8, two indentations 2211 are provided in two opposite edges of the body 220, respectively. It should be noted that, usually, a power module is provided, at one or two opposite sides thereof, with connections or terminals 240 to be connected to a circuit, other modules, other components or the like, as shown in Fig. 3. In such condition, the indentations may be formed in a side or two opposite side of the body other than the sides where the connections or terminals are provided.

The indentations 2211 may be formed in different shapes. For example, each indentation 2211 may be in the shape of a rounded rectangle, as shown in Figs. 3-4 and 8. In other examples, each indentation may be in the shape of a semi-circle, semi-ellipse, rectangle or the like. The shape of the indentation 2211 may be determined according to the shape of the electronic component 230 encapsulated in the body or the region occupied by the electronic component 230.

It should be noted that there may be one or more electronic components 230 encapsulated in the body 220, depending on practical requirement. The electronic component may be in form of a semiconducting power switch such as an isolated gate bipolar transistor (IBGT), a metal-oxide-semiconductor field-effect transistor (MOSFET) or other active or passive components that are well known in the art. Such components 230 may be mounted on some form of circuit board 250, such as a direct-copper-bonded (DCB) substrate or a direct-aluminium-bonded (DAB) substrate, a printed circuit board or other forms of mounting well known in the art. As shown in Fig. 4, the circuit board 250 is also disposed on the top surface of the base plate 210 and encapsulated by the body 220. Alternatives to this form of mounting may also include the fixing of the electronic components directly onto the base plate, or onto a lead frame which is in turn connected directly or indirectly to the base plate.

With the power module disclosed in the embodiment, there is no need to provide the base plate with mounting parts having mounting holes, thus, lateral dimension of the power module is reduced. The reduction in lateral dimension is a great advantage if the application needs more than one power module to be mounted side by side. Further, it is easier to seal small base plates than bigger ones because a small base plate is not likely to be warped. Still further, without mounting holes in the base plate, the base plate is easier to be manufactured.

Figs. 5 and 6 show that two power modules are mounted side by side by clamping devices 300. As shown, each clamping device 300 comprises a clamping member 310 and a fixing member 320. The clamping member 310 may have a plate shaped body provided with at least one protrusion 311, the protrusion 311 extends into a corresponding indentations 2211 and is pressed on a corresponding exposed part of the top surface of the base plate 210. The clamping member 310 is provided with a hole, through which the fixing member 320 may pass and fix the clamping member 310 to the substrate 400. The fixing member 320 may be, for example, a screw or a bolt, which can be passed through the hole of the clamping member 310 and fixed to a hole formed in the substrate 400.

It can be understood that the protrusion 311 may have different shapes, but preferably, the shape of the protrusion 311 is consistent or complementary with the shape of the indentation 2211.

Still referring to Figs. 5 and 6, it can be seen that the central clamping device 300 is used to clamp the two power modules 200 arranged adjacent to each other. The clamping member 310 of the central clamping device 300 is provided with four protrusions 311 extending into four indentations 2211, two of which are formed in the upper power module 200 and the other two are formed in the lower power module 200. The upper and lower clamping devices 300 may have a different configuration from that of the central clamping device 300. As shown in Fig. 5, each of the upper and lower clamping devices 300 only has two protrusions 311 at one side thereof.

It can be appreciated by a person of ordinary skill that the concept shown in Figs. 5 and 6 can also be applied if a plurality of power modules 200 are arranged in a row or in an array. For the sake of simplification, the power modules 200 are represented as rectangular blocks. Fig. 7 shows four power modules 200 arranged into a 2x2 array. As shown in Fig. 7, one clamping device 300 is located between two adjacent columns of the power modules 200 and the clamping device 300 has a clamping member 310 extending along the columns. Each power module 200 is provided with two indentations at one side thereof adjacent to the clamping device 300, and the clamping member 310 is provided with eight protrusions 311 extending into eight indentations and clamped on corresponding exposed parts of base plates of the power modules 200 adjacent to the clamping member 310, respectively. The clamp member 310 is fixed to a substrate (not shown) by two fixing members 320, each of which being located between two adjacent power modules 200.

It can also be appreciated by the person of ordinary skill that there may be an upper clamping device located at an upper side of the upper column of the power modules and a lower clamping device located at a lower side of the lower column of the power modules, and each of the upper and lower clamping devices may be configured to be similar to those shown in Fig. 5, or similar to the clamping device shown in Fig. 7, but has protrusions provided at only one side thereof.

With the arrangement shown in Fig. 7, the number of clamping devices for the power modules can be significantly decreased, thus cost for the clamping devices can be reduced. Moreover, the power modules can be arranged more close to each other and fixed together by the clamping device such that the system can be more compact. Usually, where clamping devices are not used as in the prior art power modules, fixing members need to pass through corresponding fixing parts of a power module to fix it onto the substrate. The fixing parts occupy spaces, such that more spaces are needed in the electrical device.

Figs. 9 and 10 show a power module according to another embodiment of the present disclosure, and Figs. 11 and 12 shows that the power module is assembled with a clamping member.

Referring to Figs. 9 and 10, a power module 200 is of a different type from that shown in Fig. 3. However, general configuration of the power module 200 is similar to that shown in Fig. 3. A difference between the two power modules 200 lies in that the openings 221 of the power module 200 of Figs. 9 and 10 are in a different form. As shown in Figs. 9 and 10, six holes 2212 are provided in the body 220, and parts of the top surface of the base plate 210 are accessible from the holes 2212. Although the holes 2212 shows in Fig. 9 are circular holes, it can be appreciated by a person of ordinary skill that the holes may have different shapes. Moreover, there may be more or less holes, depending on practical conditions, such as size of the power module.

Six holes 2212 are located adjacent to two opposite sides of the body 220 of the power module 200 symmetrically. However, the positions of the holes may vary. For example, if four electronic components encapsulated in the body 220 are located at four quadrants of the body and there is sufficient distances therebetween, then one or more holes may be located at the center of the body 220. The positions of the holes may be determined based on practical situations.

The clamping device 300 is then constructed to adapt to the configuration of the power module 200. As shown in Figs. 11 and 12, the clamping member 310 is configured to extend above the edge portion the body 220 and cover the holes 2212. The clamping member 310 is provided with protrusions 311 extending downwards from a bottom surface of the clamping member 310 at positions aligned with the positions of the holes 2212 and passing through the holes 2212 and pressing against the upper surface of the base plate 210 of the power module 200. It should be understood that, another clamping member may be provided at an opposite side of the power module 200.

It can be appreciated by a person of ordinary skill that the concepts shown in Figs. 5-7 can also be applied to the embodiment shown in Figs. 9 to 12. To be specific, the clamping member 310 shown in Fig. 10 may be configured to extend above edges portions of two adjacent power modules arranged side by side and cover the holes of the two power modules, and the clamping member 310 may be provided with at the bottom surface thereof with downward protrusions extending into the holes of the two power modules respectively. Further, the clamping member may be configured to extend along two columns of a power module array and used to clamp power modules arranged in the columns.

Although several exemplary embodiments have been shown and described, it would be appreciated by those skilled in the art that various changes or modifications may be made in these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the claims and their equivalents.

List of reference numerals

100 Power Module

110 Base Plate

120 Molded Body

130 Fixing Part

140 Fixing Member

200 Power Module

210 Base Plate

220 Molded Body

221 Opening

2211: Indentation

2212: Hole

230 Electronic Component

240 Terminal/Connection

250 Circuit Board

300 Clamping Device

310 Clamping Member

311 Protrusion

320 Fixing Member

400 Substrate