TWI445491B - Sandwich structures and methods of cooling, shielding emi noises and carrying currents for mini-modules - Google Patents

Description

Sandwich structure for micro-components and method for cooling, shielding electromagnetic interference and current carrying of micro-components

Embodiments of the present invention relate to a micro-component, and more particularly to a sandwich structure for thermal cooling and EMI shielding in a micro-element.

Today, micro-components are rapidly developing due to their small size and low power consumption. At present, the package form of micro components mainly uses wire bonding technology. However, in the wire bonding technique, since the bonding wires are long and the lead resistance is large, the power loss of the micro components is increased and the efficiency is lowered. This limits the ability to carry large currents. Moreover, since the bonding leads are thin, parasitic inductance will be generated, so that the switches in the micro components will generate an oscillating circuit when switching, and the generation of the oscillating circuit will cause additional loss in the circuit and generate electromagnetic interference (EMI) noise. . In addition, the wire bonding technique can only dissipate the heat generated by the micro components from the bottom surface, and therefore, the heat dissipation capability is poor. With today's increasing load currents, the requirements for component heat dissipation are becoming higher and higher, and wire bonding technology is no longer the best package for micro components.

Therefore, there is a need for a novel package structure to reduce power loss and electromagnetic interference in micro-components and to improve their heat dissipation capability.

In view of one or more problems in the prior art, it is an object of the present invention to provide a sandwich structure and method for a microcomponent.

In one aspect of the invention, embodiments of the present invention provide a sandwich structure for a microcomponent, the sandwich structure comprising: a top layer structure for thermal cooling, electromagnetic interference shielding, and current carrying, wherein The top layer structure has a top surface and a bottom surface; an underlayer structure for thermal cooling, current carrying, and circuit control, wherein the underlying structure has a top surface and a bottom surface; internal components, wherein the internal components Including a first set of elements, the first set of elements including one or more elements, and wherein a first side of each of the elements is mounted on a top surface of the underlying structure; a first set of connected structures, wherein The set of connection structures includes one or more connection structures, each of the first set of connection structures for connecting each of the first set of elements to the bottom surface of the top layer structure; the second set of connections a structure, wherein the second set of connection structures comprises one or more connection structures, the second set of connection structures being attached to a bottom surface of the top structure and a top of the bottom structure Between, provided with one or more current path for said internal element.

In another aspect of the present invention, an embodiment of the present invention provides a method for cooling a micro-component, shielding electromagnetic interference of a micro-element, and carrying current, comprising: mounting a first set of components on a top surface of the underlying structure, Wherein the first set of components includes one or more components for thermal cooling, current carrying, and circuit control; connecting the first side of each of the first set of connection structures to the top layer structure, wherein A set of connection structures includes one or more connection structures for thermal cooling, electromagnetic interference shielding, and current carrying; connecting a first side of each of the second set of connection structures to a bottom surface of the top layer structure The second set of connection structures includes one or more connection structures for providing one or more current channels for the micro-components; and the second side of each of the first set of connection structures Connected to each of the first set of elements; and connect a second side of each of the second set of connected structures to a top surface of the underlying structure.

With the embodiment of the invention, double-sided cooling of the micro component can be realized, the heat dissipation capability of the micro component can be improved, power dissipation of the micro component can be reduced, and the electromagnetic interference resistance of the micro component can be improved.

The sandwich structure for a micro component of the embodiment of the present invention will be described in detail below. In the following description, some specific details are provided to provide a better understanding of the embodiments of the invention. Those skilled in the art will appreciate that embodiments of the present invention can be implemented even in the absence of some detail or a combination of other methods, elements, materials, and the like.

FIG. 1 shows a typical DC/DC (DC/DC) buck converter circuit 10. As shown in FIG. 1, the circuit 10 includes a controller coupled to the gates of the upper tube FET1 and the lower tube FET2. The drain of the upper FET 1 is coupled to the input terminal VIN, and the source thereof is coupled to the drain of the lower FET 2 . The source of the lower FET 2 is coupled to ground. One end of the inductor L is coupled to the common terminal of the upper tube FET1 and the lower tube FET2, and the other end is coupled to the output terminal VOUT. In the present embodiment, the controller and the upper tube FET1 are integrated in the same wafer 101.

2A and 2B illustrate a novel sandwich structure that implements the DC/DC buck converter circuit 10 of FIG. 1 in accordance with one embodiment of the present invention. As shown in FIGS. 2A and 2B, the wafer 101 is mounted on a substrate on the bottom surface by flip chip bonding so that the front surface of the wafer 101 is ground, and the reverse surface thereof is adhered to the substrate by a conductive paste such as solder paste. The lower tube FET2 and the inductor L are also mounted on the substrate through the conductive paste. The mounting process can be implemented by conventional conventional reflow processes.

Metal vias A and C are respectively used to connect the wafer 101 and the lower tube FET 2 to a metal lead frame located on the top surface, and the metal lead frame is connected to each device of the micro component through a silver epoxy resin or a solder paste. The metal lead frame covers all of the components of the microcomponent. Due to the presence of the metal vias A and C, the heat generated by the wafer 101 and the lower FET 2 can be dissipated from the substrate by conventional methods, and can also be emitted from the metal lead frame through the metal vias A and C, that is, using metal vias. The holes enable double-sided cooling of the micro-components. The metal lead frame is used as a power ground shield to block EMI noise. The substrate in FIGS. 2A and 2B may be a printed circuit board (PCB) having a different type of core material, or a metal film. Both the metal leadframe and the substrate can be used for current carrying or as a control signal trace. The metal via B is directly connected between the metal lead frame and the substrate to connect the power ground of the metal lead frame to the substrate ground. The metal via B replaces the conventional wire bond connection to provide a current path from the lower FET 2 to the substrate for current carrying.

In another embodiment, the metal vias B can be used to transfer signals or carry current between the metal leadframe and the substrate.

In one embodiment, the metal leadframe can be a flat or sealed enclosure and completely cover the microelements.

In one embodiment, there may be multiple openings in the metal leadframe.

In one embodiment, when the metal lead frame is a flat plate, the insulating material is filled in the voids of the micro-component. Specifically, the mold composite can be injected into the micro-component through the opening in the metal lead frame, and the package thus formed is relatively strong. Injection of the mold composite into the micro-components also produces electrical insulation. The mold composite can be a silicone. In addition, the opening can also reduce eddy currents, thereby more effectively improving the electromagnetic shielding effect.

The inductor L is connected to the metal lead frame through the silver epoxy resin, which can help the heat dissipation of the micro component and improve the efficiency.

Although three metal through holes A, B, and C are shown as examples of the connection structure, the number of connection structures in the present invention is not limited to this specific example, and any suitable number of connection structures may be employed in practice depending on the application requirements.

Figure 3 illustrates an improved sandwich structure in accordance with another embodiment of the present invention. As shown in FIG. 3, the internal components D1 and D2 of the micro-component are connected to the metal lead frame through the first set of metal vias D and the second set of metal vias E, respectively, compared to the structures shown in FIGS. 2A and 2B. . The use of a plurality of small through holes can reduce the thermal stress of the internal components, and the thermal stresses of the plurality of small through holes together are less than the thermal stress of a metal through hole, and the internal components D1 and D2 can be avoided. Being crushed.

Although two internal elements D1 and D2 are shown as examples of internal elements, the number of internal elements in the present invention is not limited to this specific example, and any suitable number of internal elements may be employed in practice depending on the application requirements.

Figure 4 illustrates an improved sandwich structure in accordance with another embodiment of the present invention. As shown in FIG. 4, the metal lead frame is fabricated to have a sealed cover structure having an open bottom surface as compared with the structure shown in FIGS. 2A and 2B. The sealing cover is attached to the substrate through a silver epoxy or solder paste and completely covers the entire micro-component. The structure eliminates the need for mold composites, thus saving costs. In addition, the sealing cover prevents magnetic leakage at the side of the micro-component, thereby improving the EMI shielding effect. Moreover, the structure shown in FIG. 4 provides an additional thermal path for heat dissipation of the micro-components by directly connecting the metal lead frame to the substrate, thereby improving the thermal performance of the micro-elements.

The above description and embodiments of the present invention are merely illustrative of the sandwich structure for the micro-components of the embodiments of the present invention and the method thereof, and are not intended to limit the scope of the present invention. Variations and modifications of the disclosed embodiments are possible, and other possible alternative embodiments and equivalent variations to the elements of the embodiments will be apparent to those of ordinary skill in the art. Other variations and modifications of the disclosed embodiments of the invention do not depart from the spirit and scope of the invention.

10. . . DC/DC (DC/DC) Buck Converter Circuit

101. . . Wafer

A, B, C. . . Metal through hole

D1, D2. . . Internal component

D. . . First set of metal through holes

E. . . Second set of metal through holes

FIG. 1 shows a typical DC/DC (DC/DC) buck converter circuit 10.

2A shows a side view of a micro-element structure implementing the DC/DC buck converter circuit 10 of FIG. 1 in accordance with one embodiment of the present invention.

2B shows a top view of a micro-element structure implementing the DC/DC buck converter structure 10 of FIG. 1 in accordance with one embodiment of the present invention.

Figure 3 shows a side view of a micro-element structure in accordance with another embodiment of the present invention.

4 shows a side view of a micro-element structure in accordance with another embodiment of the present invention.

101. . . Wafer

A, B, C. . . Metal through hole

Claims (15)

A sandwich structure for a micro component, the sandwich structure comprising: a top metal lead frame for thermal cooling, electromagnetic interference shielding, and current carrying, wherein the top metal lead frame has a top surface And a bottom substrate; the underlying substrate for thermal cooling, current carrying, and circuit control, wherein the underlying substrate has a top surface and a bottom surface; internal components, wherein the internal component includes a first set of components, the first set of components Including one or more components, and wherein a first side of each of the components is mounted on a top surface of the substrate; a first set of connection structures, wherein the first set of connection structures includes one or more connection structures Each of the first set of connection structures is configured to connect each of the first set of components to a bottom surface of the top metal lead frame; a second set of connection structures, wherein the second set of connections The structure includes one or more connection structures connected between the bottom surface of the top metal lead frame and the top surface of the bottom substrate. Providing one or more internal components for the current channel. The sandwich structure of claim 1, wherein each of the first set and the second set of connection structures comprises one or more metal vias. The sandwich structure of claim 1, wherein the top metal lead frame and the underlying substrate are substrates or metal lead frames. The sandwich structure of claim 1, wherein the first side of the first set and the second set of connection structures are connected to the bottom surface of the top metal lead frame through a conductive paste, the first set of connections The second side of the structure is connected to the first set of elements through a conductive paste, and the second set of connection structures are connected to the top surface of the underlying substrate through the conductive paste. The sandwich structure of claim 1, wherein the top metal lead frame is a flat plate or a sealed cover, the top metal lead frame completely covering the micro-component. The sandwich structure of claim 1, wherein the top metal lead frame has an opening. The sandwich structure according to claim 6, wherein when the top metal lead frame is a flat plate, the void of the micro element is filled with an insulating material. The sandwich structure of claim 1, wherein the internal component further comprises a second set of components, the second set of components being connected to the bottom surface of the top metal lead frame or the top of the bottom substrate through the conductive paste surface. The sandwich structure of claim 8, wherein a first face of each of the second set of components is mounted on a top surface of the base substrate, each of the second set of components The second side is connected to the top metal lead frame through the conductive paste. The sandwich structure of claim 1, wherein the sandwich structure further comprises a third set of components mounted on a top surface of the top metal leadframe, the third set of components comprising one or more components. Electromagnetic interference for cooling micro components and shielding micro components And a method of carrying current, comprising: mounting a first set of components on a top surface of the underlying substrate, wherein the first set of components includes one or more components, the underlying substrate being used for thermal cooling, current carrying, and circuit control; a first side of each of the first set of connection structures is coupled to a bottom surface of the top metal lead frame, wherein the first set of connection structures includes one or more connection structures for thermal cooling, electromagnetic Interference shielding and current carrying; connecting a first side of each of the second set of connection structures to a bottom surface of the top metal lead frame, wherein the second set of connection structures includes one or more connection structures, the second a set of connection structures for providing one or more current channels for the microcomponent; a second side of each of the first set of connection structures is coupled to each of the first set of components; and the second set A second side of each of the connection structures in the connection structure is coupled to a top surface of the substrate. The method of claim 11, wherein the method further comprises: connecting a first side of each of the second set of elements to a top surface of the bottom substrate, or each of the second set of elements A second side of the component is coupled to the bottom surface of the top metal leadframe. The method of claim 11, wherein the method further comprises: mounting a third set of elements on the top surface of the top metal lead frame, the third set of elements comprising one or more elements. The method of claim 11, wherein the party The method further includes: opening a hole in the top metal lead frame. The method of claim 11, wherein the top metal lead frame is a flat plate or a sealing cover, and the flat plate or the sealing cover completely covers the micro component, wherein the method further comprises: when the top metal lead frame When it is a flat plate, an insulating material is filled in the gap of the micro component.