Patent Application
20230207420
The present disclosure relates to an electronic device and more specifically, to an integrated circuit that includes a multi-layered substrate having an improved thermal performance.
Thermal performance in integrated circuit (IC) packages with high power ratings (e.g., approximately 3.6-7.0 kW) are dependent on a heat slug or heat spreader in the IC package. The heat slug is a single piece structure in the IC package. Thus, reducing a thermal resistance of the IC package below a desired value is difficult due to the single piece structural configuration of the heat slug. In addition, circuit topologies, power output, and package layout are limited due to the single piece heat slug structure. Finally, the single piece heat slug structure cannot provide external isolation that is required with additional isolation materials such as an isolated thermal interface material or other structures to assemble with external systems or heat sinks.
In described examples, an electronic device includes a multi-layered substrate comprised of a first metal layer, a second metal layer, and an intermediate layer disposed between the first metal layer, and the second metal layer. The first metal layer is partitioned into sections where each of the sections has a first surface and electrical circuits patterned into the first surface. A lead frame is attached to the first metal layer and a die is attached to the first surface of each of the sections of the first metal layer.
In another described example, a power converter includes a multi-layered substrate comprised of a first metal layer, a second metal layer, and an intermediate layer disposed between the first metal layer, and the second metal layer. The first metal layer is partitioned into a first section having a first surface, a second section having a first surface, and a third section having a first surface. Electrical circuits are patterned into the first surface of the first section, the first surface of the second section, and the first surface of the third section. A lead frame is attached to outer portions of the first metal layer. A die is attached to the first surface of the first section, the first surface of the second section, and the first section of the third section.
In another described example, a method includes providing a multi-layered substrate, the multi-layered substrate having a first metal layer, a second metal layer, and an intermediate layer disposed between the first metal layer and the second metal layer, the first metal layer partitioned into sections. A lead frame is attached to outer portions of the first metal layer. A die is attached to a first surface of each of the partitioned sections of the first metal layer and wire bonds are attached from the die of each of the partitioned sections to the lead frame. A mold compound is formed over portions of the lead frame, the multi-layered substrate, each die, and the wire bonds.
Disclosed herein is a system and method of fabricating an electronic device and more specifically and integrated circuit (IC) package. The IC package can be comprised of a power small outline package (PSOP) that can include one or more gallium nitride field-effect transistors (GaN FET's) for use in power electronics (e.g., power converters, power switching, etc.). Conventional PSOP's include a heat slug or heat spreader that limit the thermal performance of the IC package when used in higher power applications in the range of 3.6-7.0 kW. In addition, as mentioned above, circuit topologies, power output, and package layout are limited due to the single piece heat slug structure.
To improve thermal and electrical performance, the IC package replaces the heat slug with a direct bonded copper (DBC) substrate that includes a ceramic layer and a metal (e.g., copper) layer disposed on each side of the ceramic layer. DBC substrate technology using ceramic and metal materials have excellent thermal and electrical conductivity and good mechanical properties. Conversely, commonly used substrate materials (e.g., glass-epoxy) are insufficient in power electronic modules due to the poor thermal dissipation properties. Still further, with the trend of miniaturizing power electronic modules, DBC substrate technology facilitates the fabrication of the copper layers having a thickness of hundreds of micrometers in one processing step.
A lead frame is attached to a first metal layer of the substrate. In addition, the first metal layer is partitioned into multiple sections where one or more of the multiple sections can be patterned to include complex electrical circuits, such as half-bridge circuits, full-bridge circuits, etc. that include FET's, gate drive IC's, controllers and passive components (e.g., capacitors, resistors, inductors, etc.) to improve the electrical performance of the IC package. Electrical components (e.g., a die including a GaN FET, passive components (e.g., capacitors, inductors, etc.), etc.) can be attached to one or more multiple sections of the first metal layer. The ceramic layer can be made from aluminum oxide (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4) or another type of ceramic material having similar thermal and electrical properties. The ceramic layer provides electrical isolation from external components and improves the thermal performance of the IC package. Specifically, the ceramic layer improves the thermal performance of the IC package by approximately 40% over the conventional PSOP IC package operating in the 3.6-7.0 kW range.
The multi-layered substrate 102 is comprised of a first metal layer 112 and a second metal layer 114. The first and second metal layers 112, 114 are formed from an electrically conductive material (e.g., copper). An intermediate layer 116 made from a ceramic material (e.g., aluminum oxide (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4) or another type of ceramic material having similar thermal and electrical properties) is disposed between the first and second metal layers 112, 114.
The first metal layer 112 is partitioned into multiple sections (e.g., two or more sections). For the purpose of illustrative simplicity, in the example illustrated in
In another example, the first metal layer 112 can be partitioned into more than two sections, where a first section includes a die having a first GaN FET configured to operate as a high-side switch, a second section that includes a die having a second GaN FET configured to operate as a low-side switch, and a third section can include a die having a control module to drive the electronic device 100. In this scenario, the entire operational unit of the electronic device (e.g., power converter) 100 can be packaged in a single IC package.
As mentioned above, complex circuit topologies, power output, and package layout are limited due to the single piece heat slug structure. Thus, in the example illustrated in
Specifically,
Referring to
At 404, solder is deposited via a soldering process (e.g., paste printing, screen printing, etc.) on outer portions of an exposed (first) surface (e.g., first surface 122, 124) of the first metal layer. At 406, a lead frame (e.g., lead frame 104) is attached to the first surface of the first metal layer at locations (i.e., outer portions) where the solder is printed or deposited. At 408, the electronic device undergoes a reflow process via a reflow oven to melt the solder at a specific temperature to form a tight, conductive bond between the first metal layer and the lead frame. At 410, electrical circuits are patterned on the first surface of each section of the first metal layer. At 412, a die (e.g., die 106) and other electronic components are attached to the first surface each section of the first metal layer. At 414, wire bonds (e.g., wire bonds 108) are attached from the die and other electronic components to the lead frame. At 416, a mold compound (e.g., mold compound 110) is formed over the multi-layered substrate die, the wire bonds, and portions of the lead frame and cured during a curing process thereby forming the electronic device. The mold compound is formed such that the mold compound encapsulates the substrate the die, the other electronic components, and the wire bonds. The mold compound can be made from an epoxy or epoxy blends, silicone, polyimide, etc.
Described above are examples of the subject disclosure. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the subject disclosure, but one of ordinary skill in the art may recognize that many further combinations and permutations of the subject disclosure are possible. Accordingly, the subject disclosure is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. In addition, where the disclosure or claims recite “a,” “an,” “a first,” or “another” element, or the equivalent thereof, it should be interpreted to include one or more than one such element, neither requiring nor excluding two or more such elements. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim. Finally, the term “based on” is interpreted to mean based at least in part.
