Flip-chip soldered packaging structure and its formation method

Abstract

This application provides a flip-chip bonding package structure and its forming method. The flip-chip bonding package structure includes: a copper frame, which includes a main side frame and a secondary side frame disposed opposite to each other; a U-shaped copper conductor, which is integrally formed with the main side frame of the copper frame through its bent portion, and the U-shaped copper conductor has a contact surface away from the copper frame; a chip, which is mounted on the side of the copper frame away from the U-shaped copper conductor; and a molding compound, which encapsulates the copper frame, the chip, and the side of the U-shaped copper conductor that contacts the copper frame, and exposes the remaining portion of the U-shaped copper conductor. Thus, the flip-chip bonding package structure is bonded to external components through the contact surface and dissipates heat through the portion of the U-shaped copper conductor exposed outside the molding compound. The above technical solution improves the reliability and stability of the product and enables continuous operation.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing, and more particularly to a flip-chip bonding package structure and a method for forming the same. Background Technology

[0002] Due to its advantages such as high system integration, low production cost, short market launch cycle, excellent performance, high reliability, small size, light weight, and high packaging density, the conventional Small Outline Package (SOP) is a very common component packaging form. In existing SOP packages, all external leads extend from within the black encapsulated material, with no exposed metal sheets on the front or back of the encapsulated material. The chip's functional pads are connected to the external leads using conventional ultrasonic wire bonding.

[0003] However, existing SOP packaging has the following problems: 1) The design of the SOP package current sensor structure, with current wire impedance ≥0.6mΩ, will cause the copper sheet to heat up rapidly after the product is loaded with current, and the product body temperature will rise quickly, making it unable to work continuously, thus limiting the load current to ≤60A; 2) Due to the use of ultrasonic bonding process, the product reliability can only meet the Moisture Sensitivity Level (MSL) 3 level; 3) The built-in copper wire has not been structurally optimized, and stress deformation is prone to occur in the final molding process of the product. The molded body is prone to breakage under external impact, resulting in low product yield.

[0004] Therefore, providing a flip-chip soldering packaging structure with high reliability and stability that enables products to operate continuously is an urgent problem to be solved. Summary of the Invention

[0005] The technical problem to be solved by this application is to provide a flip-chip soldering packaging structure and its formation method, which has higher reliability and stability and enables the product to work continuously.

[0006] To address the aforementioned issues, this application provides a flip-chip bonding package structure, comprising: a copper frame including a primary side frame and a secondary side frame disposed opposite to each other; a U-shaped copper conductor integrally formed with the primary side frame through its bend, the U-shaped copper conductor having a contact surface away from the copper frame; a chip mounted on the side of the copper frame away from the U-shaped copper conductor; and a molding compound encapsulating the copper frame, the chip, and the side of the U-shaped copper conductor that contacts the copper frame, while exposing the remaining portion of the U-shaped copper conductor. Thus, the flip-chip bonding package structure is bonded to external components through the contact surface and dissipates heat through the portion of the U-shaped copper conductor exposed outside the molding compound.

[0007] In some embodiments, the copper frame is made of non-magnetic copper material, and the thickness of the copper frame ranges from 0.38 to 0.5 mm.

[0008] In some embodiments, the main side frame has a groove formed outside the contact area with the U-shaped copper wire, the depth of the groove being half the thickness of the copper frame; the groove is filled with an insulating resin layer to isolate moisture and electrical components.

[0009] In some embodiments, the main side frame has at least one locking hole penetrating the copper frame at the bend near the U-shaped copper conductor, the locking hole being used to enhance the bonding ability between the copper frame and the molding compound.

[0010] In some embodiments, the flip-chip bonding package structure further includes at least one first copper pillar, which is disposed on the main side frame near the U-shaped copper conductor to support the chip.

[0011] In some embodiments, the secondary side frame has at least one pin, the pin being disposed opposite to the U-shaped copper wire, and the first end of the pin being close to the bend of the U-shaped copper wire and embedded in the encapsulation.

[0012] In some embodiments, the flip-chip soldering package structure further includes at least one second copper pillar disposed at the first end of the pin for electrical connection within the flip-chip soldering package structure.

[0013] This application also provides a method for forming a flip-chip bonded package structure, the method comprising: providing a copper material layer; patterning the copper material layer to form a copper frame and a U-shaped copper conductor, wherein the copper frame includes a main side frame and a secondary side frame disposed opposite to each other, the U-shaped copper conductor is integrally formed with the main side frame through its bent portion, and the U-shaped copper conductor has a contact surface away from the copper frame; mounting a chip on the side of the copper frame away from the U-shaped copper conductor; and molding to form a molded package, wherein the molded package encapsulates the copper frame, the chip, and the side of the U-shaped copper conductor that contacts the copper frame, and exposes the remaining portion of the U-shaped copper conductor, thereby the flip-chip bonded package structure is bonded to an external component through the contact surface and dissipates heat through the portion of the U-shaped copper conductor exposed outside the molded package.

[0014] In some embodiments, the step of patterning the copper material layer further includes: using a semi-etching process to etch the area outside the contact area between the main side frame and the U-shaped copper wire to form a groove with a depth of half the thickness of the copper frame; the method further includes: filling the groove with resin material to form an insulating resin layer that isolates moisture and electricity.

[0015] In some embodiments, the copper frame is made of non-magnetic copper, and the thickness of the copper frame ranges from 0.38 to 0.5 mm.

[0016] In some embodiments, the step of patterning the copper material layer further includes: forming at least one locking hole through the copper frame at the bend of the main side frame near the U-shaped copper conductor, the locking hole being used to enhance the bonding ability between the copper frame and the molding compound.

[0017] In some embodiments, the step of patterning the copper material layer further includes: forming at least one pin on the secondary side frame, the pin being disposed opposite to the U-shaped copper wire.

[0018] In some embodiments, prior to the step of mounting the chip on the side of the copper frame away from the U-shaped copper conductor, the method further includes: forming at least one first copper pillar on the main side frame near the U-shaped copper conductor, and forming at least one second copper pillar at the first end of the pin near the bend of the U-shaped copper conductor, wherein the first copper pillar is used to support the chip, and the second copper pillar is used for electrical connection within the flip-chip bonding package structure.

[0019] The above technical solution designs the U-shaped copper conductor and the pin as a planar structure, exposed within the molding compound. This not only allows for complete contact with the pads on the PCB board, but also ensures that when the copper frame carries a large current (meeting a continuous load current of 100A), the heat generated by the product's structural temperature rise is promptly dissipated through the U-shaped copper conductor and the pin. This maximizes the removal of heat from the copper loss, thereby controlling the product's temperature rise and preventing damage. This solution solves the problems of rapid heat generation on the copper sheet after current loading, preventing sustained operation, and low product yield due to the lack of structural optimization of the internal copper conductor.

[0020] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this application. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the specific implementation of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a flip-chip soldered packaging structure in one embodiment of this application;

[0023] Figure 2 This is a schematic diagram of the copper frame in one embodiment of this application;

[0024] Figure 3 This is a schematic diagram of a method for forming a flip-chip soldered packaging structure in one embodiment of this application. Detailed Implementation

[0025] The technical solutions of the specific embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described specific embodiments are only a part of the specific embodiments of this application, and not all of the specific embodiments. Based on the specific embodiments of this application, all other specific embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] To address the problems in existing technologies, such as the rapid heat generation of the copper sheet after current loading leading to insufficient continuous operation, the use of ultrasonic bonding technology resulting in product reliability only meeting MSL3 level, and the lack of structural optimization of the built-in copper wires causing low product yield, this application provides a flip-chip soldered package structure and its formation method.

[0027] The following is a description of a flip-chip soldering packaging structure provided by a specific embodiment of this application. Figure 1 This is a schematic diagram of a flip-chip soldered packaging structure in one embodiment of this application. Please refer to the following: Figure 1 The flip-chip soldering package structure includes: a copper frame 1, a U-shaped copper wire 2, and a chip 3 (illustrated in...). Figure 2The copper frame 1 includes a main side frame 11 and a secondary side frame 12 disposed opposite to each other. The U-shaped copper conductor 2 is integrally formed with the main side frame 11 of the copper frame 1 through its bend 21, and the U-shaped copper conductor 2 has a contact surface 22 away from the copper frame 1. The chip 3 is mounted on the side of the copper frame 1 away from the U-shaped copper conductor 2. The molded package 4 encapsulates the copper frame 1, the chip, and the side of the U-shaped copper conductor 2 that contacts the copper frame 1, and exposes the remaining part of the U-shaped copper conductor 2, so that the flip-chip soldered package structure is fully attached to external components (e.g., pads on a PCB board) through the contact surface 22 and dissipates heat through the portion of the U-shaped copper conductor 2 exposed outside the molded package 4.

[0028] Please continue reading below. Figure 1 In this embodiment, the main side frame 11 of the copper frame 1 has at least one locking hole 5 penetrating the copper frame 1 near the bend 21 of the U-shaped copper conductor 2. The locking hole 5 is used to enhance the bonding ability between the copper frame 1 and the molding compound 4. By providing the locking hole 5, the risk of delamination between the copper frame 1 and the molding compound 4 is reduced, and the stress generated by the shear force on the product molding compound during external molding is also reduced, further preventing product cracking.

[0029] Please continue reading below. Figure 1 The secondary side frame 12 of the copper frame 1 has at least one pin 8, the pin 8 is disposed opposite to the U-shaped copper wire 2, and the first end 81 of the pin 8 is close to the bend of the U-shaped copper wire 2 and embedded in the encapsulation body 4.

[0030] Figure 2 This is a schematic diagram of a copper frame in one embodiment of this application. Please refer to the following. Figure 2 The copper frame shown is along Figure 1 A schematic diagram of the cross-section AA'. In this embodiment, the main side frame 11 of the copper frame 1 has a groove 6 formed outside the contact area with the U-shaped copper wire 2. The depth of the groove 6 is half the thickness of the copper frame 1. The groove 6 is filled with an insulating resin layer to isolate moisture and electrical components. In this embodiment, the secondary side frame 12 of the copper frame 1 also has a groove 6 formed on the side of the first end 81 of each pin 8 away from the chip 3. The depth of the groove 6 is half the thickness of the copper frame 1. The groove 6 is filled with an insulating resin layer to isolate moisture and electrical components. The grooves 6 at the main side frame 11 and the secondary side frame 12 can be formed using the same process.

[0031] In this embodiment, the copper frame is made of non-magnetic copper material, such as non-magnetic copper material that does not contain iron or nickel, or other non-magnetic materials that can conduct electricity. Since the non-magnetic copper material does not contain iron or nickel, it will not affect the magnetic field. The detected change in magnetic flux around the chip 3 is generated by the change in primary-side current and has no impact on the detection results. In this embodiment, the thickness of the copper frame 1 ranges from 0.38 to 0.5 mm.

[0032] Please continue reading below. Figure 1 In this embodiment, the flip-chip bonding package structure further includes at least one first copper pillar 71, which is disposed on the main side frame 11 of the copper frame 1 near the U-shaped copper wire 2, and is used to support the chip 3.

[0033] Please continue reading below. Figure 1 In this embodiment, the flip-chip soldering package structure further includes at least one second copper pillar 72, which is disposed at the first end 81 of the pin 8 for electrical connection inside the flip-chip soldering package structure.

[0034] In some embodiments, a flip-chip soldering process is used to package the product in order to meet the high reliability MSL1 level requirements.

[0035] The above technical solution designs the U-shaped copper wire 2 and the pin 8 as a planar structure, exposing most of the structure outside the molding compound 4. This not only allows for complete contact with the pads on the PCB board, but also ensures that when the copper frame 1 carries a large current, the heat generated by the temperature rise of the product body structure is promptly dissipated through the U-shaped copper wire 2 and the pin 8. This structural design maximizes the removal of heat from the copper loss, thereby controlling the temperature rise of the product body and preventing damage. This application solves the problems of rapid heat generation of the copper sheet after current loading in SOP packaged current sensor structures, resulting in the product's reliability only meeting the MSL3 level due to the use of ultrasonic bonding technology, and low product yield due to the lack of structural optimization of the built-in copper wires.

[0036] Based on the same inventive concept, this application also provides a method for forming a flip-chip soldered packaging structure.

[0037] Figure 3 This is a schematic diagram of a method for forming a flip-chip soldered package structure according to an embodiment of this application. Please refer to the following: Figure 3The method for forming the flip-chip bonding package structure includes: step S301, providing a copper material layer; step S302, patterning the copper material layer to form a copper frame and a U-shaped copper conductor, wherein the copper frame includes a main side frame and a secondary side frame arranged opposite to each other, the U-shaped copper conductor is integrally formed with the main side frame through its bent portion, and the U-shaped copper conductor has a bonding surface away from the copper frame; step S303, mounting a chip on the side of the copper frame away from the U-shaped copper conductor; step S304, molding to form a molding compound, wherein the molding compound encapsulates the copper frame, the chip, and the side of the U-shaped copper conductor that contacts the copper frame, and exposes the remaining part of the U-shaped copper conductor, so that the flip-chip bonding package structure is bonded to external components through the bonding surface and dissipates heat through the part of the U-shaped copper conductor exposed outside the molding compound.

[0038] In this embodiment, the copper frame is made of non-magnetic copper, such as non-magnetic copper without iron or nickel, or other non-magnetic materials that can conduct electricity. Since non-magnetic copper does not contain iron or nickel, it will not affect the magnetic field. The detected change in magnetic flux around chip 3 is generated by the change in current of the main edge frame and has no impact on the detection results. In this embodiment, the thickness of the copper frame 1 ranges from 0.38 to 0.5 mm.

[0039] In this embodiment, step S302, which involves patterning the copper material layer, further includes: using a semi-etching process to etch the area outside the contact area between the main side frame 11 of the copper frame 1 and the U-shaped copper conductor 2 to form a groove 6 with a depth half the thickness of the copper frame 1; in this embodiment, the method further includes: filling the groove 6 with resin material to form an insulating resin layer that isolates moisture and electricity. The formed copper frame can be found in [reference needed]. Figure 2 As shown.

[0040] In this embodiment, step S302, which involves patterning the copper material layer, further includes: forming at least one adhesive-locking hole 5 through the copper frame at the bend of the main side frame 11 near the U-shaped copper conductor 2. The adhesive-locking hole 5 enhances the bonding between the copper frame 1 and the molding compound 4. The formed copper frame can be found in [reference needed]. Figure 1 As shown. In this embodiment, since the copper frame 1 and the U-shaped copper wire 2 are designed to be integrally connected, the copper frame 1 is embedded in the entire encapsulation body as an extension of the U-shaped copper wire 2. At the same time, the structure has been optimized by adding two locking holes 5, which enhances the bonding ability between the entire copper frame 1 and the encapsulation body 4, reduces the risk of delamination between the copper frame 1 and the encapsulation body 4, and also reduces the stress generated by the shear force on the encapsulation body of the product during external molding, further preventing product cracking.

[0041] In this embodiment, the step of patterning the copper material layer in step S302 further includes: forming at least one pin 8 on the secondary side frame 12 of the copper frame 1, wherein the pin 8 is disposed opposite to the U-shaped copper wire. The formed copper frame can be referred to... Figure 1 As shown. In this embodiment, the secondary side frame 12 of the copper frame 1 also has a groove 6 formed on the side of the first end 81 of each pin 8 away from the chip 3. The depth of the groove 6 is half the thickness of the copper frame 1. The groove 6 is filled with an insulating resin layer to isolate moisture and electrical components. The formed copper frame can be seen in [reference needed]. Figure 2 As shown, the grooves 6 at the main side frame 11 and the secondary side frame 12 can be formed using the same process.

[0042] In some embodiments, the copper wire of the high-current isolated Hall current sensor prepared by the above method has a copper frame thickness of 0.38–0.5 mm and a minimum width of 0.7–1.0 mm. Through the design of the grooves 6 at the main side frame 11 and the secondary side frame 12, the entire frame design can adopt a planar shape (specifically, the U-shaped copper wire 2, pins 8, and the contact surfaces of the molding compound 4 with external components are on the same plane). The etching process etches the required pattern onto the copper strip. After pattern optimization of the copper frame 1, the copper frame 1 can meet the requirements of high-current applications while satisfying low impedance (impedance value ≤ 0.2 mΩ) and low power loss, and allows a continuous load current ≤ 100 A.

[0043] In this embodiment, before step S302, which describes loading the chip 3 on the side of the copper frame away from the U-shaped copper wire, the method further includes: forming at least one first copper pillar 71 on the main side frame of the copper frame 1 near the U-shaped copper wire 2, and forming at least one second copper pillar 72 on the first end 81 of the pin 8 near the bend 21 of the U-shaped copper wire 2, wherein the first copper pillar 71 is used to support the chip 3, and the second copper pillar 72 is used for electrical connection inside the flip-chip bonding package structure.

[0044] In some embodiments, a flip-chip soldering process is used to package the product in order to meet the high reliability MSL1 level requirements.

[0045] The above technical solution designs the U-shaped copper wire 2 and the pin 8 as a planar structure, exposing most of the structure to the plastic package 4. This not only allows for complete contact with the pads on the PCB board, but also ensures that when the copper frame 1 carries a large current, the heat generated by the temperature rise of the product body structure is promptly dissipated through the U-shaped copper wire 2 and the pin 8. This structural design maximizes the removal of heat from the copper loss, thereby controlling the temperature rise of the product body and preventing damage. This solves the problems of rapid heat generation on the copper sheet after current loading in SOP package current sensor designs, which prevents continuous operation; the use of ultrasonic bonding technology limiting product reliability to MSL3 level; and the low product yield due to the lack of structural optimization of the built-in copper wires.

[0046] It should be noted that, in this document, relational terms such as "second" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "also includes a..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0047] The various specific embodiments in this specification are described in a related manner. Similar or identical parts between the different embodiments can be referred to interchangeably. Each specific embodiment focuses on its differences from other embodiments. In particular, the specific embodiments of the method are basically similar to the specific embodiments of the structure, so the description is relatively simple; relevant parts can be referred to the descriptions of the specific embodiments of the structure.

[0048] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A flip-chip soldered packaging structure, characterized in that, include: A copper frame, comprising a main side frame and a secondary side frame disposed opposite to each other; a U-shaped copper conductor, the U-shaped copper conductor being integrally formed with the main side frame through its bent portion, the U-shaped copper conductor having a contact surface away from the copper frame; a chip, mounted on the side of the copper frame away from the U-shaped copper conductor; and a molding compound, the molding compound encapsulating the copper frame, the chip, and the side of the U-shaped copper conductor that contacts the copper frame, and exposing the remaining portion of the U-shaped copper conductor, thereby allowing the flip-chip package structure to be bonded to external components through the contact surface and to dissipate heat through the portion of the U-shaped copper conductor exposed outside the molding compound. The copper frame has a groove outside the contact area with the U-shaped copper wire, and the depth of the groove is half the thickness of the copper frame; the groove is filled with an insulating resin layer to isolate moisture and electrical components. The secondary side frame has at least one pin, which is disposed opposite to the U-shaped copper wire, and the first end of the pin is close to the bend of the U-shaped copper wire and embedded in the encapsulation.

2. The flip-chip soldering packaging structure according to claim 1, characterized in that, The copper frame is made of non-magnetic copper material, and the thickness of the copper frame ranges from 0.38 to 0.5 mm.

3. The flip-chip soldering packaging structure according to claim 1, characterized in that, The main side frame has at least one locking hole penetrating the copper frame at the bend near the U-shaped copper conductor. The locking hole is used to enhance the bonding ability between the copper frame and the molding compound.

4. The flip-chip soldering packaging structure according to claim 1, characterized in that, The flip-chip bonding package structure further includes at least one first copper pillar, which is disposed on the main side frame near the U-shaped copper conductor to support the chip.

5. The flip-chip soldering packaging structure according to claim 1, characterized in that, The flip-chip soldering package structure further includes at least one second copper pillar, which is disposed at the first end of the pin for electrical connection within the flip-chip soldering package structure.

6. A method for forming a flip-chip soldered package structure as described in claim 1, characterized in that, The method includes: providing a copper material layer; patterning the copper material layer to form a copper frame and a U-shaped copper conductor, wherein the copper frame includes a main side frame and a secondary side frame disposed opposite to each other, the U-shaped copper conductor is integrally formed with the main side frame through its bend, and the U-shaped copper conductor has a bonding surface away from the copper frame; mounting a chip on the side of the copper frame away from the U-shaped copper conductor; and molding to form a molded package, wherein the molded package encapsulates the copper frame, the chip, and the side of the U-shaped copper conductor that contacts the copper frame, and exposes the remaining portion of the U-shaped copper conductor, thereby the flip-chip soldered package structure is bonded to an external component through the bonding surface and dissipates heat through the portion of the U-shaped copper conductor exposed outside the molded package.

7. The method according to claim 6, characterized in that, The step of patterning the copper material layer further includes: using a semi-etching process to etch the area outside the contact area between the main side frame and the U-shaped copper wire to form a groove with a depth of half the thickness of the copper frame; the method further includes: filling the groove with resin material to form an insulating resin layer that isolates moisture and electricity.

8. The method according to claim 6, characterized in that, The copper frame is made of non-magnetic copper, and the thickness of the copper frame ranges from 0.38 to 0.5 mm.

9. The method according to claim 6, characterized in that, The step of patterning the copper material layer further includes: forming at least one locking hole through the copper frame at the bend of the main side frame near the U-shaped copper conductor, the locking hole being used to enhance the bonding ability between the copper frame and the molding compound.

10. The method according to claim 6, characterized in that, The step of patterning the copper material layer further includes: forming at least one pin on the secondary side frame, wherein the pin is disposed opposite to the U-shaped copper wire.

11. The method according to claim 10, characterized in that, Before the step of mounting the chip on the side of the copper frame away from the U-shaped copper conductor, the method further includes: forming at least one first copper pillar on the main side frame near the U-shaped copper conductor, and forming at least one second copper pillar at the first end of the pin near the bend of the U-shaped copper conductor, wherein the first copper pillar is used to support the chip, and the second copper pillar is used for electrical connection inside the flip-chip bonding package structure.

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