Circuit board assembly and method

Abstract

The invention relates to a circuit board assembly (10) comprising: an insert (12); a printed circuit board (PCB) (32) to which the interposer (12) is connected; at least one semiconductor device (38); a main connection between the interposer (12) and the semiconductor device (38); and a secondary connection between the interposer (12) and the semiconductor device (38). The secondary connection provides electrical and thermal communication between the semiconductor device (38) and the interposer (12) when the primary connection fails. The main connection between the interposer (12) and the semiconductor device (38) is a sintered connection. The interposer (12) and the semiconductor device (38) are in electrical and thermal communication with each other by a sintered connection. The sintered connection includes a sintered compound connecting the interposer (12) and the semiconductor device (38). And if the primary connection fails, the secondary connection comprises a limp home function.

Description

Technical Field

[0001] The present invention relates to a circuit board assembly and a method for providing a circuit board assembly. The present invention relates to a circuit board assembly having at least one semiconductor device and an interposer, wherein the semiconductor device is connected to the interposer using a primary connection and a secondary connection such that if the primary connection fails, the secondary connection still provides electrical and thermal communication between the semiconductor device and the interposer. Background Art

[0002] Vehicles typically include the use of some type of power module to perform various functions. A power module typically includes an integrated circuit (IC) in a packaged module. Power modules with lower power requirements may have discrete components mounted on a printed circuit board (PCB). The arranged IC must be connected to these discrete components and also include some type of housing to protect the IC. The housing may be in the form of gel, overmolding, etc. Manufacturing a power module with this type of housing results in a high level of complexity.

[0003] If discrete components are used on a PCB, the current carrying capacity of the component is often limited by the way the discrete components are connected to the PCB (such as by using pins.) In this case, it is also not possible to achieve optimal heat dissipation when using discrete components on a PCB, as pin connections are known to have poor thermal conductivity (i.e., approximately 0.3-0.5 W / mK).

[0004] Therefore, a need exists for a connection between at least one discrete component and a PCB that provides adequate heat dissipation and current carrying capabilities. Summary of the invention

[0005] It is therefore an object of the present invention to provide a circuit board assembly having a connection between at least one discrete component, such as a semiconductor device, and a PCB that eliminates the above-mentioned drawbacks of complexity, current carrying capacity, and heat dissipation.

[0006] This object is achieved by a circuit board assembly according to independent claim 1 and a method according to independent claim 9. Preferred embodiments are given in the dependent claims.

[0007] In one embodiment, the present invention is a circuit board assembly that reduces the complexity in manufacturing, thereby allowing the use of ICs with various discrete components, such as semiconductor devices, which are packaged and have defined connections. Since the semiconductor has been removed from the wafer and has been packaged, the handling of the discrete components is also simplified. Therefore, only a small amount of electrostatic discharge (ESD) measures are required to protect the semiconductor devices during handling and assembly. In order to achieve high current carrying capacity, the circuit board assembly of the present invention includes integrating one or more discrete components into the circuit via a drain pin, and also includes using a large rear protrusion (i.e., a tab) for this purpose. In order to promote the desired heat dissipation, the PCB includes one or more holes. An insert made of a material with a high thermal conductivity coefficient and a high current carrying capacity (e.g., copper) is at least partially inserted into at least one of the holes. The connection between the PCB and the insert can be achieved in any suitable manner. Due to the connection between the PCB and the semiconductor, the insert can be held in place relative to the PCB, or the insert can be connected to the PCB by a press-in operation or a press-fit connection, using fasteners such as screws, or utilizing any other interconnection technology. The semiconductor is connected to the PCB, for example, by sintering or welding. This ensures good heat dissipation and promotes electrical connectivity. A discrete component including a semiconductor device is at least partially positioned on an insert, wherein a portion of the insert is inserted into a hole in a PCB, and the insert is connected to the PCB. The connection is typically achieved by soldering or sintering to transfer current from the PCB to the discrete component, such as the insert and the semiconductor device. In one embodiment, a layer of sintering compound is attached to the insert, which is used to achieve a flat current-carrying connection with the PCB. In one embodiment, the PCB has a complementary copper geometry, possibly with an Au or Ag coating. In addition, an embodiment of a circuit board assembly includes an insert having a defined area or protrusion that can be inserted into the PCB. These protrusions also extend at least partially through the PCB, and the drain pin can be soldered to the mounting surface of one or more corresponding protrusions of the insert. This further increases the current-carrying capacity, or, if the flat current-carrying connection fails, acts as a limp home functionality. When using lower currents, emergency operation is ensured.

[0008] In one embodiment, the present invention is a circuit board assembly comprising an interposer; a printed circuit board (PCB) to which the interposer is connected; at least one semiconductor device; a primary connection between the interposer and the semiconductor device; and a secondary connection between the interposer and the semiconductor device. In one embodiment, the secondary connection provides electrical communication between the semiconductor device and the interposer when the primary connection fails.

[0009] In one embodiment, the main connection between the interposer and the semiconductor device is a sintered or soldered connection. The interposer and the semiconductor device are in electrical and thermal communication with each other via this connection.

[0010] In an embodiment, the sintered connection includes a sintering or soldering compound connecting the interposer and the semiconductor device.

[0011] In one embodiment, the secondary connection includes a limp home function if the primary connection fails.

[0012] In an embodiment, the secondary connection between the interposer and the semiconductor device comprises a solder connection.

[0013] In one embodiment, at least one protrusion is integrally formed as part of the insert, wherein the protrusion is part of the primary connection. At least one hole is integrally formed as part of the PCB, and when the insert is assembled to the PCB, the protrusion at least partially extends into the hole.

[0014] In one embodiment, at least one rod is integrally formed as part of the insert, at least one extension is integrally formed as part of the rod, the extension is part of the secondary connection, and the second hole is integrally formed as part of the PCB. When the insert is assembled to the PCB, the extension integrally formed as part of the rod extends at least partially into the second hole.

[0015] In an embodiment, the outer mounting surface of the protrusion, the mounting surface of the extension, and the outer surface of the PCB are in the same plane relative to each other.

[0016] In one embodiment, the present invention is a method for providing multiple connections between an interposer and at least one semiconductor device of a circuit board assembly. The method includes the steps of providing an interposer, providing a printed circuit board (PCB), and providing at least one semiconductor device. The method also includes the steps of connecting the interposer to the PCB; connecting the interposer to the semiconductor device such that a primary connection exists between the interposer and the semiconductor device, and a secondary connection exists between the interposer and the semiconductor device. The method also includes the steps of operating the circuit board assembly using a limp home function using the secondary connection if the primary connection fails. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter.It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for illustration purposes only and are not intended to limit the scope of the invention.

[0018] The present invention will become more fully understood from the detailed description and the accompanying drawings, in which:

[0019] Figure 1 is a top view of a portion of a circuit board assembly according to an embodiment of the present invention;

[0020] Figure 2 is a bottom view of a semiconductor device as a part of a circuit board assembly according to an embodiment of the present invention;

[0021] Figure 3 It is along Figure 1 a cross-sectional view taken along line 3-3 of ;

[0022] Figure 4A is a side view of an interposer as part of a circuit board assembly according to an embodiment of the present invention;

[0023] Figure 4B is a top view of an interposer as part of a circuit board assembly according to an embodiment of the present invention; and

[0024] Figure 5 is a perspective view of an interposer as part of a circuit board assembly according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] Figure 1 1 and 2, and a circuit board assembly 10 having various connection features according to the present invention is shown in general at 10. Referring generally to the drawings, the circuit board assembly 10 includes an insert, generally at 12. As shown in FIGS. 4b and 5, the insert 12 includes a plurality of rods 14a, 14b, 14c, 14d that are connected to various components of the circuit board assembly 10. More specifically, in the illustrated embodiment, the circuit board assembly 10 includes a plurality of semiconductor devices connected in parallel to each other, and the rods 14a, 14b, 14c, 14d are part of a common drain connection for each semiconductor device. The number of rods 14a, 14b, 14c, 14d may vary, depending on how many semiconductor devices are used. The insert 12 also includes a body 16, and each rod 14a, 14b, 14c, 14d extends from the body 16. There are several extensions 18a, 18b, 18c, 18d, integrally formed as part of and projecting from a corresponding rod 14a, 14b, 14c, 14d, which are used to provide the various connections described.

[0026] refer to Figure 4A-5 , a fastening rod 20 having a threaded hole 22 is also integrally formed as part of the body 16. Rods 14b, 14c, 14d also have corresponding threaded holes. The first rod 14a is generally L-shaped and also includes a threaded hole 24, and a cylindrical extension 56, wherein the cylindrical extension 56 includes an aperture for solder pin connection. There are additional threaded holes 26 formed as part of the body 16, wherein the threaded holes 22, 24, 26 are used to connect the body 16 to various components of the circuit board assembly 10.

[0027] refer to Figure 3-5, the insert 16 further includes a first protrusion 28 and a second protrusion 30. The first protrusion 28 extends away from the body 16 in a first direction, and the second protrusion 30 extends away from the body 16 in a second direction.

[0028] Reference now Figure 3 , the interposer 12 is mounted to a printed circuit board (PCB) 32 using a connecting material 34, which in this embodiment is a sintering paste or sintering compound 34. The sintering compound 34 is also used to connect at least one electrical component to the outer mounting surface 36 of the first protrusion 28. In the embodiment shown, the electrical component is a semiconductor device 38. The connection between the semiconductor device 38 and the interposer 12 provides a first electrical and thermal connection, so that the semiconductor device 38 and the interposer 12 are in electrical and thermal communication with each other.

[0029] The PCB 32 includes several holes, and each extension 18 a , 18 b , 18 c , 18 d extends into a corresponding hole of the PCB 32 . Figure 3 Two of the holes 40 a , 40 b are shown in FIG. 4 , wherein the extension 18 a of the first rod 14 a extends into the hole 40 a , and the first protrusion 28 extends into the hole 40 b of the PCB 32 .

[0030] Each extension 18a, 18b, 18c, 18d includes a corresponding mounting surface 42a, 42b, 42c, 42d. Figure 3 , the mounting surfaces 42a, 42b, 42c, 42d of the extensions 18a, 18b, 18c, 18d and the outer mounting surface 36 of the first protrusion 28 are substantially in the same plane 54 relative to each other. The outer surface 44 of the PCB 32 may also be in the same plane 54 or have a small offset.

[0031] The semiconductor device 38 includes a connection pin 46 connected to the mounting surface 42a of the extension 18a, thereby providing a second electrical and thermal connection or a secondary connection, wherein the connection pin 46 provides electrical and thermal communication between the semiconductor device 38 and the interposer 12. The secondary connection can be a solder connection and is achieved by soldering the end of the connection pin 46 to the mounting surface 42a.

[0032] The semiconductor device 38 also includes several connection pins 58a, 58b, 58c. Connection pin 58a is connected to the PCB 32 and acts as a source drain, connection pin 58b is connected to a driver used as a Kelvin source, and connection pin 58c is connected to a driver used as a gate connection.

[0033] As mentioned above, the posts 14a, 14b, 14c, 14d of the circuit board assembly 10 are part of a common drain connection for each semiconductor device mounted to the PCB 32, and each post 14a, 14b, 14c, 14d has an extension 18a, 18b, 18c, 18d. In the embodiment shown, the mounting surfaces 42b, 42c, 42d of the extensions 18b, 18c, 18d are used for connection with more than one semiconductor device to increase the current carrying capacity, and can vary in number.

[0034] refer to Figure 1-2 , semiconductor device 38 also includes a housing 48, which in this embodiment is an overmold material. Housing 48 does not surround the entire semiconductor device 38. There are exposed metal areas that serve as mounting surfaces 50. Mounting surfaces 50 are exposed metal areas to which sintering compound 34 is attached, thereby attaching semiconductor device 38 to interposer 12 so that semiconductor device 38 is in electrical and thermal communication with interposer 12. There are also several areas 52, which are Figure 1 4 is a portion of housing 48 that protects various components of semiconductor device 38 .

[0035] Referring again generally to the drawings, during operation, the first electrical connection between the semiconductor device 38 and the insert 12 is the primary connection between the semiconductor device 38 and the insert 12. The insert 12 also acts as a heat sink and dissipates heat from the semiconductor device 38 and the PCB 32. There may be a situation where, during operation of the circuit board assembly 10, the primary connection fails, such as by an inadequate connection between the semiconductor device 38 and the insert 12. This may be the result of degradation of the sintering compound 34. If the primary connection fails, the secondary connection between the connecting pin 46 and the mounting surface 42a of the extension 18a still provides electrical communication between the semiconductor device 38 and the insert 12. This secondary connection allows the circuit board assembly 10 to operate in a "limp home" mode, in which the circuit board assembly 10 maintains minimal functionality. In one embodiment, the circuit board assembly 10 is used as part of an electric vehicle. When operating in the "limp home" mode, the vehicle's electric motor can continue to operate with a minimal amount of current consumption. Since less heat is transferred through the connection pins 46 during normal operation (ie, when the primary connection is functioning properly), heat dissipation from the semiconductor device 38 is reduced.

[0036] The present invention is a circuit board assembly 10 having a PCB 32 and an insert 12 connected to the PCB 32. The insert 12 is connected to the PCB 32 using a primary connection and a secondary connection. The primary connection between the semiconductor device 38 and the insert 12 serves as a first electrical and thermal connection. In one embodiment, a sintering compound 34 is used to connect the semiconductor device 38 and the insert 12 to achieve the first connection. The sintering compound 34 can also be used to connect the semiconductor device 38 to the PCB 32. The secondary connection includes a connection pin 46 of the semiconductor device 38, which is connected to the mounting surface 42a of the extension 18a, wherein the extension 18a is integrally formed as a part of the rod 14a of the insert 12. Several additional extensions 18b, 18c, 18d are formed as a part of the corresponding rod 14b, 14c, 14d of the insert 12, and each extension 18b, 18c, 18d has a corresponding mounting surface 42b, 42c, 42d. The connecting pins 46 realize electrical and micro-thermal connections and provide electrical communication between the semiconductor device 38 and the insert 12. The PCB 32 also includes a plurality of holes 40a, 40b. Each extension 18a, 18b, 18c, 18d extends at least partially into a corresponding one of the holes 40a, and another protrusion 28 of the insert 12 extends at least partially into another hole 40b, so that the mounting surfaces 42a, 42b, 42c, 42d of the extensions 18a, 18b, 18c, 18d, the outer mounting surface 36 of the first protrusion 28, and the outer surface 44 of the PCB 32 are substantially in the same plane 54 relative to each other. In an alternative embodiment, the PCB 32 can be offset relative to the plane 54. During operation, if the primary connection fails, the secondary connection between the connecting pins 46 and the mounting surface 42a of the extension 18a still provides electrical and thermal communication between the semiconductor device 38 and the insert 12.

Claims

1. A circuit board assembly (10), comprising: - an insert (12); - a printed circuit board (PCB) (32), to which the insert (12) is connected; - at least one semiconductor device (38); - a main connection between the insert (12) and the at least one semiconductor device (38); as well as - a secondary connection between the interposer (12) and the at least one semiconductor device (38); - wherein the secondary connection provides electrical and thermal communication between the at least one semiconductor device (38) and the interposer (12) when the primary connection fails.

2. The circuit board assembly of claim 1, wherein the main connection between the insert (12) and the at least one semiconductor device (38) further comprises a sintered connection, wherein the insert (12) and the at least one semiconductor device (38) are electrically and thermally connected to each other via the sintered connection.

3. The circuit board assembly of claim 1 or 2, the sintered connection further comprising a sintering compound connecting the insert (12) and the at least one semiconductor device (38).

4. Circuit board assembly according to one of the preceding claims, the secondary connection further comprising a limp home function if the primary connection fails.

5. The circuit board assembly of claim 4, the secondary connection between the interposer (12) and the at least one semiconductor device (38) further comprising a solder connection.

6. The circuit board assembly according to one of the preceding claims, further comprising: - at least one protrusion (28) formed integrally as part of the insert (12), said at least one protrusion (28) being part of the main connection; as well as - at least one hole (40a, 40b) formed integrally as part of the PCB (32); - wherein when the insert (12) is assembled to the PCB (32), the at least one protrusion (28) at least partially extends into the at least one hole (40a, 40b).

7. The circuit board assembly of claim 6, further comprising: - at least one rod (14a, 14b, 14c, 14d) formed integrally as part of the insert (12); - at least one extension (18a) formed integrally as part of said at least one rod (14a, 14b, 14c, 14d), the extension (18a) being part of the secondary connection; as well as - a second hole (40a, 40b) formed integrally as part of the PCB (32); - wherein when the insert (12) is assembled to the PCB (32), the extension (18a) integrally formed as part of the at least one rod (14a, 14b, 14c, 14d) extends at least partially into the second hole (40a, 40b).

8. A circuit board assembly according to claim 7, wherein the outer mounting surface (36) of the at least one protrusion (28), the mounting surface (42a) of the extension (18a), and the outer surface (44) of the PCB (32) are in the same plane (54) relative to each other or with a small offset.

9. A method for providing a plurality of connections between an interposer (12) and at least one semiconductor device (38) of a circuit board assembly (10), comprising the steps of: - providing an insert (12); - providing a printed circuit board (PCB) (32); as well as - providing at least one semiconductor device (38); - connecting the insert (12) to the PCB (32); - connecting the interposer (12) to the at least one semiconductor device (38) such that there is a primary connection between the interposer (12) and the at least one semiconductor device (38) and there is a secondary connection between the interposer (12) and the at least one semiconductor device (38); - If the primary connection fails, the circuit board assembly (10) is operated using a limp home function using the secondary connection.

10. The method according to claim 9, further comprising the following steps - providing at least one rod (14a, 14b, 14c, 14d) integrally formed as part of the insert (12); - providing at least one protrusion (28) integrally formed as part of the insert (12), said at least one protrusion (28) being part of the primary connection; and - providing at least one hole (40a, 40b) integrally formed as part of the PCB (32); - providing at least one extension (18a) integrally formed as part of said at least one rod (14a, 14b, 14c, 14d), said at least one extension (18a) being part of a secondary connection; - providing a second hole (40a, 40b) formed integrally as part of the PCB (32); - connecting the insert (12) to the at least one semiconductor device (38) so that the at least one protrusion (28) extends at least partially into the at least one hole (40a, 40b), the extension (18a) formed as an integral part of the insert (12) extends at least partially into the second hole (40a, 40b), and the outer mounting surface (36) of the at least one protrusion (28), the mounting surface (42a) of the extension (18a), and the outer surface (44) of the PCB (32) are in the same plane (54) relative to each other or with a small offset.

11. The method according to claim 10, further comprising the steps of: The interposer (12) is connected to the at least one semiconductor device (38) using a sintering compound, thereby forming a primary connection.

12. The method according to claim 10, further comprising the steps of: The interposer (12) is connected to the at least one semiconductor device (38) using connecting pins (46) to form a secondary connection.

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