Patent Application
20160141275
Some electronic modules are constructed using a direct bonded copper (“DBC”) substrate. DBC substrates may be formed from a ceramic insulator with copper directly bonded to one side of the ceramic insulator. Although DBC substrates provide for increased thermal resilience of the semiconductor die, they drastically increase the difficulty of testing components before assembly. Additionally, assembly costs for DBC substrate components are high relative to non-DBC components. Furthermore, it is difficult to scale both components formed on DBC substrates. More specifically, it is difficult to scale the number of components possible to include on one device when the components are mounted to a DBC substrate. Additionally the number of circuit topologies available can be limited. The present disclosure is directed towards these concerns.
The following is a simplified summary in order to provide a basic understanding of some embodiments described herein. This summary is not an extensive overview, and it is not intended to identify key/critical elements or to delineate the scope thereof. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.
Various embodiments are generally directed towards an electronic device formed from a number of discrete semiconductor components that provide increased thermal resilience over conventional techniques. The electronic device according to various embodiments of the present disclosure may be scaled to provide a variety of different components and/or circuit topologies while still maintaining thermal resilience over conventional techniques.
In one embodiment, discrete electronic devices are mounted on a baseplate, preferably with electrical leads oriented away from the baseplate. An electronic device is typically understood to refer to a physical entity used in an electronic system to affect electrons or electrical fields. The baseplate may comprise a thermally conductive material, such as copper, to allow for the transfer of heat away from the internally isolated discrete electronic devices.
In one embodiment, the devices are mounted on the baseplate using a mechanical fastener, such as screws, spring clips, and the like. In one embodiment, each device has electrical leads formed at 90 degree angles to the baseplate to provide a through hole printed circuit board (“PCB”) mount. The assembly may be soldered into a PCB which provides the specific topology required. One or more application-specific heat sinks may be mounted onto the baseplate. The entire assembly may be overmolded by injection molded or potted using an encapsulant.
The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings. It is to be appreciated however, that the foregoing claims may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the claimed subject matter to those of ordinary skill in the art. In the drawings, like numbers refer to like elements throughout.
Turning more specifically to
In some examples, the discrete electronic devices are internally isolated from each other. More specifically, each discrete electronic device 120-a is electrically isolated from the other devices 120-a. In some examples, the discrete electronic devices 120-a may have a casing that operates to internally isolate the device. The casing may be made from metal, plastic, glass, ceramic, or another insulating material.
Some advantages of internal isolation include protection against impact and corrosion, stable holds for contact pins or leads (which are used to connect the device to external circuits), and dissipation of heat produced in the device. Furthermore, an advantage to using internally isolated discrete electronic devices 120-a in the device 100 is that each discrete electronic device 120-a may be tested before the device 100 is assembled and/or completely formed.
The device 100 further includes a baseplate 140. Each discrete electronic device 120-a is affixed to the baseplate 140.
In general, the baseplate 140 may comprise any of a variety of thermally conductive materials. For examples, the baseplate 140 may be copper, silver, gold, aluminum, iron, steel, brass, bronze, mercury, graphite, or an alloy including one or more of these or other thermally conductive materials.
It is to be appreciated, that the discrete electronic devices 120-a may include any number of electrical leads 110-ab, with the number of leads being dependent upon the nature of each individual discrete electronic device 120-a. However, the discrete electronic devices 120-a are shows having three (3) electrical leads 110-ab for convenience and clarity. In particular, discrete electronic device 120-1 includes electrical leads 110-11, 110-12, and 110-13. Discrete electronic device 120-2 includes electrical leads 110-21, 110-22, and 110-23. Discrete electronic device 120-3 includes electrical leads 110-31, 110-32, and 110-33. Discrete electronic device 120-4 includes electrical leads 110-41, 110-42, and 110-43. Discrete electronic device 120-5 includes electrical leads 110-51, 110-52, and 110-53. Discrete electronic device 120-6 includes electrical leads 110-61, 110-62, and 110-63. Each discrete electronic device 120 may be an electronic device such as a thyristor, a diode, a transistor, or another type of electronic device. Each discrete electronic device 120 is internally isolated, meaning it has a casing that may be made from metal, plastic, glass, ceramics, or other materials. Each discrete electronic device 120 may include individual discrete components etched in silicon wafer.
Thermal interface material 150 is shown between the discrete electronic devices 120-a and baseplate 140. Thermal interface material 150 may be a viscous fluid substance with properties akin to grease, which increases the thermal conductivity of baseplate 140 and discrete electronic devices 120-a by filling air-gaps present due to imperfections in the surfaces of discrete electronic devices 120-a and baseplate 140, thereby allowing further heat dissipation. In one example, thermal interface material 150 may comprise metal oxide and nitride particles suspended in silicone thermal compounds. In other examples, thermal interface material 150 may comprise water, thermal grease, aluminum oxide, zinc oxide, steel, sodium fluoride aluminum, copper, silver, diamond, beryllium oxide, aluminum nitride, zinc oxide, silicon dioxide, gallium, or other materials.
It is to be appreciated, that the discrete electronic devices 120-a may include any number of electrical leads 110-ab, with the number of leads being dependent upon the nature of each individual discrete electronic device 120-a. However, the discrete electronic devices 120-a are shown having electrical leads 110-1 and 110-2 for convenience and clarity. In this example, electrical leads 110-1 and 110-2 are oriented away from baseplate 140.
During normal operations, discrete electronic devices 120-a may generate significant amounts of heat. If the heat generated during the operation of discrete electronic devices 120-a is not removed, then discrete electronic devices 120-a or other devices near them may overheat, resulting in damage to discrete electronic devices 120-a, damage to devices near them, or causing degradation of performance. In this example, application specific heat sink 310 has been mounted onto baseplate 140 to assist in heat dissipation. There may be a need to balance the heat-dissipating requirements of the heat sink 310 with other factors. Heat sink 310 may crack, damage or separate from the electronic components they are attached to if the heat sink has a coefficient of thermal expansion significantly different from the baseplate 140 or other attached components. Also, many materials used to make heat sinks are relatively heavy. If discrete electronic devices 120-a or other parts of the assembly are subjected to vibration or impact, the weight of heat sink 310 may crack, damage or cause heat sink 310 to separate from baseplate 140. Thus, it may be advantageous to optimize heat dissipation, weight, cost, machinability and other features of when selecting a heat sink. Accordingly, the heat sink 310 may be specific to the application of device 300.
With some examples, measures may be taken in order to protect against shock and vibration and to protect electronic components against moisture and corrosive agents. In particular, the assembly may be potted with encapsulant 320. Encapsulant 320 may be a solid or gelatinous compound that provides resistance to shock and vibration, and assists with exclusion of moisture and corrosive agents. Encapsulant 320 may comprise a compound such as polyurethane or silicone.
It is to be appreciated, that the discrete electronic devices 120-a may include any number of electrical leads 110-ab, with the number of leads being dependent upon the nature of each individual discrete electronic device 120-a. However, the discrete electronic devices 120-a are shown having electrical leads 110-1 and 110-2 for convenience and clarity. Application specific heat sink 310 has been mounted onto baseplate 140. Measures may be taken in order to protect against shock and vibration and to protect electronic components against moisture and corrosive agents. In this example, the assembly has been overmolded via injection molding. In this procedure, materials have been placed into a heated barrel, mixed, and forced into the cavity formed by heat sink 310 where the material cools and hardens to configuration 420. Example materials include metals, glasses, elastomers, and confections, as well as thermoplastic and thermosetting polymers.
It is to be appreciated, that the discrete electronic devices 120-a may include any number of electrical leads 110-ab, with the number of leads being dependent upon the nature of each individual discrete electronic devices 120-a. However, the discrete electronic devices 120-a are shown having electrical leads 110-1 and 110-2 for convenience and clarity. It may be desirable to mechanically support and electronically connect electronic devices 120-a. In this example, electrical leads 110-a have been soldered onto printed circuit board (PCB) 510 having electrical leads 520-a, such that printed circuit board 510 mechanically supports and electrically connects discrete electronic devices 120-a. PCB 510 may include conductive tracks, pads and other features etched from electrically conductive sheets laminated onto a non-conductive substrate. Using PCB 510 may be less expensive and faster than other methods of electronically connecting discrete electronic device 120 because the procedure for assembly may be automated. There may be additional benefits to using PCB 510, for example wiring errors may be reduced. Alternative ways of electronically connecting discrete electronic devices 120 are possible, including manual wire wrapping and point-to-point construction using terminal strips.
It is to be appreciated, that the discrete electronic devices 120-a may include any number of electrical leads 110-ab, with the number of leads being dependent upon the nature of each individual discrete electronic device 120-a. However, the discrete electronic devices 120-a are shown having electrical leads 110-1 and 110-2 for convenience and clarity. Electrical leads 110-1 and 110-2 have been soldered onto PCB 510 having electrical leads 520-1 and 520-2. Application specific heat sink 310 has been mounted onto baseplate 140. The assembly has then been potted with encapsulant 320.
It is to be appreciated, that the discrete electronic devices 120-a may include any number of electrical leads 110-ab, with the number of leads being dependent upon the nature of each individual discrete electronic device 120-a. However, the discrete electronic devices 120-a are shown having electrical leads 110-1 and 110-2 for convenience and clarity. In this example, electrical leads 110-1 and 110-2 are oriented away from baseplate 140. Electrical leads 110-1 and 110-2 have been soldered onto PCB 510 having electrical leads 520-1 and 520-2. Application specific heat sink 310 has been mounted onto baseplate 140. The assembly has been overmolded via injection molding. In this procedure, materials have been placed into a heated barrel, mixed, and forced into the cavity formed by heat sink 310 where the material cools and hardens to configuration 420. Example materials include metals, glasses, elastomers, and confections, as well as thermoplastic and thermosetting polymers.
It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be covered by the appended claims.
