Patent Application
20210335689
The present invention generally relates to semiconductor packaging, and particularly to packaging for semiconductor devices for attachment to a printed circuit board (PCB).
There are known power semiconductor devices which are disposed in packages that conform to various packaging standards utilizing through-hole and surface-mount technologies. Packages which are utilized by power semiconductor devices include, for example, TO-247 (
In a number of instances, power semiconductor devices using conventional packages undesirably result in a more complex assembly process for attaching a heat sink and for assembly of an electronics device incorporating the power semiconductor device. Some conventional packages also limit the use of semiconductor devices that are rated for surface mount technology (SMT) temperature processing. Further, conventional power semiconductor packages utilizing through-hole technology (THT) occupy a larger space on a PCB due to device manufacturer recommendations for providing mechanical support for the lead base.
Example embodiments overcome the deficiencies of known packages for power semiconductor devices and satisfy a need for an improved semiconductor device package. According to an example embodiment, there is disclosed a power semiconductor device, including: a housing; a semiconductor die forming at least one semiconductor component, the semiconductor die being disposed within the housing; and one or more first pins extending from the housing. One or more bond wires electrically connect the one or more first pins with the semiconductor die. A heat slug is thermally coupled to the semiconductor die and at least partly disposed within the housing. One or more second pins coupled to the housing which are not connected to a bond wire or to the at least one semiconductor component.
Each of the one or more first pins and the one or more second pins includes a compliant pin configured for providing a press-fit connection with a printed circuit board when partly inserted therein.
The semiconductor die is attached to the heat slug with a thermally conductive adhesive.
The one or more second pins is thermally connected to the heat slug. In one aspect, each second pin extends from the heat slug at a location external to the housing. In another aspect, each second pin extends from or is thermally connected to the heat slug at a location internal to the housing.
The housing includes an encapsulant formed or molded over the semiconductor die.
The heat slug is disposed along a top portion of the housing. A surface of the heat slug is exposed for attachment of an external heat sink thereto.
According to another example embodiment, an electronics device includes a printed circuit board and a plurality of electrical or electronic components connected to the printed circuit board. A first electrical or electronic component of the plurality of electrical or electronic components includes a housing, a semiconductor die forming at least one semiconductor component, the semiconductor die being disposed within the housing, one or more first pins extending from the housing, and one or more bond wires electrically connecting the one or more first pins with the semiconductor die. A heat slug is thermally coupled to the semiconductor die and at least partly disposed within the housing. One or more second pins is connected to the heat slug.
Aspects of the invention will be explained in detail below with reference to exemplary embodiments in conjunction with the drawings, in which:
The following description of the example embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. In the figures and throughout the detailed description, the same reference numbers are used to identify identical or similar elements. For the sake of clarity, the elements are not shown to scale unless otherwise specified.
The example embodiments are generally directed to a semiconductor device, such as a power semiconductor device, having compliant pins and a heat slug that is also connected to a compliant pin. With the heat slug disposed in the upper portion of the semiconductor device, heat dissipation from the semiconductor device is improved and heat dissipation strategies are simplified. The semiconductor device provides a more robust and more cost effective assembly of an electronics device which utilizes the semiconductor device.
Semiconductor device 100 further includes pins 104 which extend from housing 102 and are configured to connect to a PCB. Pins 104 provide electrical connections to a semiconductor die 106 within housing 102. Instead of being through-hole or surface mounted pins, pins 104 are compliant pins which provide a press-fit engagement with the PCB. A lengthwise portion of each pin 104 is resiliently compressible in the lateral direction such that during insertion of the pin portion in an aperture defined in the PCB, the portion compresses laterally inwardly and after insertion presents a laterally outwardly force against the PCB aperture to create the press-fit engagement with the PCB. In the example embodiments illustrated, the pins 104 are located on, and extend from, opposed sides of housing 102, but it is understood that pins 104 may extend from more or less sides of housing 102.
As shown in
Semiconductor device 100 further includes electrically conductive bond wires 110, each of which connects a bond pad of semiconductor die 106 to a pin 104 so as to provide an external electrical connection to semiconductor die 106. At least one bond wire 110′ connects a bond pad of semiconductor die 106 to heat slug 108. The bond pad of semiconductor die 106 to which bond wire 110′ is connected may be configured to be connected to ground. As shown in
In the example embodiment shown in
Though semiconductor device 100 of
Semiconductor device 500 further includes one or more pins 104′ which are connected to heat slug 108. In particular, pins 104′ are connected to heat slug 108 within housing 102. This connection provides for an electrical and thermal coupling between heat slug 108 and pins 104′. By inserting pins 104′ within an aperture of a PCB which is connected to one or more ground planes within the PCB, the PCB provides heat sinking capability from semiconductor die 106 which is attached to heat slug 108, and suitably grounds the desired bond pad of semiconductor die 106. Though semiconductor device 100 of
In contrast to semiconductor device 100 of
Semiconductor devices 100 and 500 include pins 104′ connected to heat slug 108 internally and externally to housing 102, respectively. In another embodiment shown in
The use of compliant pins 104, and particularly pins 104′ which are electrically and thermally connected to heat slug 108, provide a number of advantages. For example, through-hole pins provide for a longer distance from PCB 810 to semiconductor die 106 than the distance provided by pins 104 due to the required mechanical support on the through-hole leads, according to recommendations by component manufacturers. Compliant pins 104 provide a shorter distance. For applications with higher operating frequencies such as power transformation devices (e.g., DC-to-DC converters), a shorter distance from semiconductor die 106 to PCB 810 is desired, with longer distances resulting in lower electrical efficiency of electronics device 800. The use of semiconductor devices 100 and 500 thus results in less space occupied on PCB 810.
Applications with higher power levels benefit from the use of larger package sizes for the same electronics device. Through-hole component packages such as TO-220 and TO-247 are a common choice. However, the use of these devices/packages complicates the manufacturing process because a clamping component (e.g., a screw or clip) is usually required to achieve a proper contact with a heat sink external to the electronics device. A press-fit mounting solution for semiconductor devices 100 and 500 as discussed above yields a lower bill of materials cost because the devices 100, 500 are already constrained to PCB 810 such that heat sinks can be more easily connected to housing 102 and/or heat slug 108 of devices 100, 500.
Especially with respect to conventional surface-mount semiconductor devices, semiconductor devices 100, 500 provide a much more efficient heat sink solution with heat slugs 108 exposed along the top of the semiconductor device. Some known packages with heat slugs disposed on the top of the package housing are available but they require a support method to limit lead deformation and/or solder stress during final assembly. This disadvantageously results in an imbalanced mechanical support compared to traditional surface-mount technology devices in which the heat slug 108 is also soldered to the PCB.
The use of press-fit compliant pins 104 (including pins 104′) as described above reduces the number of solder operations during manufacturing of electronics device 800. This reduces or otherwise eliminates the exposure time at elevated temperatures for electronics device 800 and its components, assemblies, etc. during manufacturing.
Further, when attaching an external heat sink to electronics device 100 or 500, vertical variation of the heat sink position may be better controlled due to the ability to use automatic press equipment.
The semiconductor devices 100 and 500 are described above as being based upon particular conventional packages. It is understood that semiconductor devices according to other embodiments may be based upon other conventional package types. In addition, it is understood that the die attach to which semiconductor die 106 is attached may be a separate element from heat slug 108 though thermally coupled thereto, and in some embodiments the die attach may be spaced apart from heat slug 108. It is further understood that each semiconductor device may include more than one semiconductor die which form the semiconductor component(s) of the semiconductor device. Such semiconductor die may, for example, be placed adjacent each other on the die attach.
The example embodiments have been described herein in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Obviously, many modifications and variations of the invention are possible in light of the above teachings. The description above is merely exemplary in nature and, thus, variations may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.
