QFN packaging device and forming method thereof

Abstract

The invention relates to a QFN packaging device and a forming method thereof. The forming method of the QFN packaging device comprises the following steps that a packaging structure is formed, the packaging structure comprises an initial frame and a plurality of initial packaging bodies located on the front face of the initial frame, the initial frame comprises a plurality of frame units, the initial packaging bodies comprise a plurality of packaging units in one-to-one correspondence with the plurality of frame units, and the initial packaging bodies are arranged on the front face of the initial frame; the back surface of the initial frame is provided with a recess which is at least partially positioned between two adjacent frame units; forming a groove extending towards the front surface of the initial frame at the bottom and the side wall of the recess; and the packaging structure is cut to form a plurality of mutually independent QFN packaging devices, and each QFN packaging device comprises a frame unit and a packaging unit above the frame unit. According to the method, the phenomena of metal burrs and metal scraping in the process of cutting the packaging structure are avoided, so that the cutting quality of the monomerization process is improved, and the manufacturing yield and the yield of the QFN packaging device are improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a QFN packaged device and a method for forming the same. Background Technology

[0002] As electronic devices develop towards miniaturization, high integration, and high reliability, QFN (Quad Flat No-lead) packages have been widely used in consumer electronics, industrial control, and automotive electronics due to their size advantage, excellent heat dissipation performance, and high soldering reliability brought about by the leadless design.

[0003] To further improve the solder joint strength and solder wetting performance of QFN package structures, recesses (dimples) are currently incorporated into the lead frame of the QFN package. However, in the mass production process of QFN packages, the package is typically cut into multiple independent QFN packages through a singulation process. This singulation process often uses a cutting blade to cut the recesses of the package. However, because the recesses contain conductive materials such as copper, copper traces remain at the edges of the cut recesses. The high-speed rotation of the cutting blade causes compression and friction on these copper traces, forming copper burrs, accompanied by metal scraping. The residual copper burrs can easily lead to short circuits between adjacent leads, while metal scraping can damage the insulation layer on the lead surface, increasing the risk of electrochemical migration. Currently, there is no effective method to remove the copper burrs in the recesses or reduce the metal scraping problem, thus reducing the reliability of the QFN packaged devices, a problem particularly prominent in automotive-grade packaging.

[0004] Therefore, how to reduce metal burrs and metal scratches in the recesses of QFN packaged devices, thereby improving the cutting quality of the monomerization process and improving the reliability of QFN packaged devices, is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] This invention provides a QFN packaged device and its forming method, which reduces metal burrs and metal scratches in the recesses of the QFN packaged device, thereby improving the cutting quality of the monomerization process and improving the reliability of the QFN packaged device.

[0006] According to some embodiments, the present invention provides a method for forming a QFN packaged device, comprising the following steps: A packaging structure is formed, the packaging structure including an initial frame and a plurality of initial packaging bodies located on the front side of the initial frame, the initial frame including a plurality of frame units, the initial packaging bodies including a plurality of packaging units corresponding one-to-one with the plurality of frame units, and the back side of the initial frame having at least a partial recess located between two adjacent frame units. Grooves extending toward the front of the initial frame are formed at the bottom and sidewalls of the recess; The packaging structure is cut to form multiple independent QFN packaged devices, each QFN packaged device including the frame unit and the packaging unit above it.

[0007] In some embodiments, the specific steps for forming the packaging structure include: The initial frame is formed, the initial frame including a front and a back side that are distributed opposite to each other, the back side of the initial frame having a recess that is at least partially located between two adjacent frame units; Multiple chips are respectively mounted onto multiple frame units, and the frame units and the chips located on top of them are electrically connected; An initial molding layer is formed by molding the initial framework and the plurality of chips using a molding process.

[0008] In some embodiments, the initial frame includes a copper alloy frame body and a metal plating layer covering the surface of the copper alloy frame body.

[0009] In some embodiments, before mounting the plurality of chips onto the plurality of frame units respectively, the following steps are further included: The initial frame is attached to an adhesive tape. The initial frame includes a plurality of frame units, each frame unit including a base island and pins located around the base island. The pins of adjacent frame units are connected to each other, and the recess is located between the pins of two adjacent frame units that are connected.

[0010] In some embodiments, the specific steps of mounting multiple chips onto multiple frame units and electrically connecting the frame units and the chips located above them include: Multiple chips are respectively mounted on the base islands of the multiple frame units; Leads that electrically connect the chip and the pins are formed on the frame unit.

[0011] In some embodiments, before forming a groove extending toward the front of the initial frame at the bottom and sidewalls of the recess, the following steps are further included: Remove the tape to expose the depression.

[0012] In some embodiments, the specific steps of forming a groove extending toward the front of the initial frame at the bottom and sidewalls of the recess include: The grooves are formed on the bottom and sidewalls of the recess from the back of the initial frame using a laser grooving process.

[0013] In some embodiments, the initial frame has cutting grooves; the specific steps of forming the grooves on the bottom and sidewalls of the recess using a laser grooving process from the back of the initial frame include: A positioning mark is formed on the back side of the initial frame; The laser used in the laser grooving process is aligned with the cutting path by the positioning mark.

[0014] In some embodiments, the specific steps of forming the groove in the bottom and sidewalls of the recess using a laser grooving process from the back of the initial frame include: While using a laser to remove the plastic sealant overflow generated during the molding process, the laser is also used to form the grooves on the bottom and sidewalls of the recess.

[0015] In some embodiments, the specific steps of forming the groove on the bottom and sidewalls of the recess using a laser grooving process from the back of the initial frame include: After removing the plastic sealant overflow generated by the plastic sealing process using a laser, the groove is formed on the bottom and sidewalls of the depression using the laser.

[0016] In some embodiments, the specific steps of forming the groove on the bottom and sidewalls of the recess using a laser grooving process from the back of the initial frame include: The laser grooving process is used to form two grooves that are symmetrically distributed about the center of the depression on the bottom and sidewalls of the depression.

[0017] In some embodiments, the specific steps of forming the groove on the bottom and sidewalls of the recess using a laser grooving process from the back of the initial frame include: The parameters of the laser grooving process are adjusted so that the depth of the groove is less than the thickness of the remaining initial frame at the bottom and sidewalls of the recess.

[0018] In some embodiments, metallic traces remain in the recess; the specific steps of forming the groove at the bottom and sidewalls of the recess using a laser grooving process from the back of the initial frame include: Adjust the parameters of the laser grooving process so that the depth of the groove is equal to the thickness of the metal trace.

[0019] In some embodiments, the metal trace is a copper trace; the specific steps for adjusting the parameters of the laser grooving process include: The wavelength of the laser used in the laser grooving process is adjusted to 1064nm or 532nm.

[0020] In some embodiments, the specific steps for adjusting the parameters of the laser grooving process further include: The power of the laser used in the laser grooving process is adjusted to 5W~20W.

[0021] In some embodiments, the specific steps of forming the groove on the bottom and sidewalls of the recess using a laser grooving process from the back of the initial frame include: The parameters of the laser grooving process are adjusted so that the sum of the distance between the two grooves and the width of the two grooves is greater than the thickness of the cutting blade, which is used to cut the packaging structure to form multiple independent QFN packaged devices.

[0022] In some embodiments, the specific steps of adjusting the parameters of the laser grooving process so that the sum of the distance between the two grooves and the width of the two grooves is greater than the thickness of the cutting blade include: Adjust the position of the two grooves and the width of each groove in the laser grooving process so that the thickness of the cutting blade is greater than the distance between the two grooves and less than the sum of the distance between the two grooves and the width of the two grooves.

[0023] In some embodiments, the specific steps of cutting the packaging structure to form multiple independent QFN packaged devices include: The package structure is cut along the cutting path using a cutting blade, with the cutting blade at least partially located within the trench, to form a plurality of independent QFN package devices.

[0024] In some embodiments, the specific steps of cutting the packaging structure along the cutting path with a cutting blade, wherein the cutting blade is at least partially located within the trench, include: The cutting blade is aligned with the cutting channel by the positioning mark, such that the cutting blade is at least partially located within the groove.

[0025] According to other embodiments, the present invention also provides a QFN packaged device, comprising: A frame unit includes a front and a back side that are relatively distributed. The back side edge of the frame unit has a notch. The notch includes a first notch and a second notch that are interconnected. The second notch is located on the side of the first notch near the back side edge of the frame unit. The encapsulation unit is located on the front side of the frame unit and is electrically connected to the frame unit.

[0026] In some embodiments, a metal trace remains within the notch, and the metal trace has a flat cut edge.

[0027] In some embodiments, the frame unit includes a base island and pins located around the base island, and the packaging unit includes a chip mounted on the base island, leads electrically connecting the chip and the pins, and a molding compound encapsulating the chip and the leads. The notch is located along the first direction on the side of the pin opposite to the base island.

[0028] In some embodiments, the frame unit includes a copper alloy frame body and a metal plating layer covering the surface of the copper alloy frame body.

[0029] In some embodiments, the maximum depth of the notch is less than the thickness of the frame unit.

[0030] In some embodiments, the maximum depth of the notch is 1 / 3 to 5 / 6 of the pin thickness.

[0031] In some embodiments, the sidewall of the second notch has laser cutting marks.

[0032] In some embodiments, the width of the second notch along the second direction is greater than the width of the first notch along the second direction, and the second direction intersects the first direction perpendicularly.

[0033] In some embodiments, the width of the first notch along the second direction is 1 / 4 to 2 / 3 of the pin width, and the width of the second notch along the second direction is greater than 2 / 3 of the pin width.

[0034] In some embodiments, the width of the second notch along the second direction is equal to the width of the pin.

[0035] In some embodiments, the two opposite sidewalls of the second notch in the second direction are molding layers.

[0036] The QFN packaged device and its forming method provided by this invention, before cutting the packaged structure, first forms grooves extending towards the front of the initial frame on the recessed bottom and sidewalls of the back side of the initial frame, and then cuts the packaged structure to form multiple independent QFN packaged devices. This pre-removal of metal burr sources on the cutting path before cutting the packaged structure avoids metal burrs and metal scratching during the cutting process, thereby improving the cutting quality of the unitization process and enhancing the reliability of the QFN packaged device. Furthermore, this invention actively removes the sources of metal burrs and metal scratching, rather than removing them through post-cutting processes, thus simplifying the manufacturing process of the QFN packaged device and improving its manufacturing efficiency.

[0037] Some embodiments of the present invention integrate the grooving process in the recess with the excess adhesive removal process after the molding process, thereby eliminating the need for new process equipment and new process steps. It is compatible with the existing manufacturing processes and procedures of QFN packaged devices, with no additional production capacity loss, thereby helping to reduce the manufacturing cost of the QFN packaged devices while improving the manufacturing yield and productivity of the QFN packaged devices. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a flowchart of a method for forming a QFN packaged device in a specific embodiment of the present invention; Figure 2 This is a top view of the initial frame in a specific embodiment of the present invention; Figure 3 yes Figure 2 A schematic diagram of the cross-section at position AB. Figure 4 This is a schematic diagram of the structure after the initial frame is attached to the tape in a specific embodiment of the present invention; Figure 5 This is a schematic diagram of the structure after multiple chips are mounted onto the initial frame in a specific embodiment of the present invention; Figure 6 This is a schematic diagram of the structure after the leads are formed on the initial frame in a specific embodiment of the present invention; Figure 7 This is a schematic diagram of the structure after the initial molding layer is formed in a specific embodiment of the present invention; Figure 8 This is a schematic diagram of the structure after removing the tape in a specific embodiment of the present invention; Figure 9 This is a schematic diagram of the structure during laser grooving in a specific embodiment of the present invention; Figure 10 This is a schematic diagram of the structure after the trench is formed in a specific embodiment of the present invention; Figure 11 This is a physical image of the object after the grooves have been formed in a specific embodiment of the present invention; Figure 12 This is a schematic diagram of the cutting and packaging structure in a specific embodiment of the present invention; Figure 13 This is a physical image of the cutting and packaging structure in a specific embodiment of the present invention; Figure 14 This is a cross-sectional schematic diagram of the QFN packaged device formed in a specific embodiment of the present invention; Figure 15 This is a three-dimensional structural diagram of the QFN device formed in a specific embodiment of the present invention; Figure 16 yes Figure 15 Enlarged view of the area within the dashed box.

[0040] Explanation of reference numerals in the attached figures 20 Initial Framework 21 islands 22 pins 30 tape 31 Depression 50 chips 60 leads 70 Initial molding layer 100 trench 120 cutting blade 130 cutting path 140 sealing layer 141 First Gap 142 Second Gap 150 gap Detailed Implementation The specific embodiments of the QFN packaged device and its formation method provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0041] This specific embodiment provides a method for forming a QFN packaged device. Figure 1 This is a flowchart illustrating the method for forming a QFN packaged device according to a specific embodiment of the present invention. Figure 1 As shown, the method for forming the QFN packaged device includes the following steps: Step S11, forming an encapsulation structure, the encapsulation structure including an initial frame and a plurality of initial encapsulation bodies located on the front side of the initial frame, the initial frame including a plurality of frame units, the initial encapsulation bodies including a plurality of encapsulation units corresponding one-to-one with the plurality of frame units, the back side of the initial frame having at least a partial recess located between two adjacent frame units; Step S12: A groove extending toward the front of the initial frame is formed at the bottom and sidewalls of the recess; Step S13: Cut the packaging structure to form multiple independent QFN packaged devices, wherein the QFN packaged device includes the frame unit and the packaging unit above it.

[0042] Figure 2 This is a top view of the initial frame in a specific embodiment of the present invention. Figure 3 yes Figure 2 A cross-sectional diagram at position AB. Figure 4 This is a schematic diagram of the structure after the initial frame is attached to the tape in a specific embodiment of the present invention. Figure 5 This is a schematic diagram of the structure after multiple chips are mounted onto the initial frame in a specific embodiment of the present invention. Figure 6 This is a schematic diagram of the structure after the leads are formed on the initial frame in a specific embodiment of the present invention. Figure 7 This is a schematic diagram of the structure after the initial molding layer is formed in a specific embodiment of the present invention. In some embodiments, the specific steps for forming the encapsulation structure include: The initial frame 20 is formed, the initial frame 20 including a front and a back side that are relatively distributed, the back side of the initial frame 20 having a recess 31 at least partially located between two adjacent frame units, such as... Figure 2 and Figure 3 As shown; Multiple chips 50 are respectively mounted onto multiple frame units, and the frame units and the chips 50 located on top of them are electrically connected, such as... Figure 5 As shown; An initial molding layer 70 is formed using a molding process to encapsulate the initial frame 20 and the plurality of chips 50, such as... Figure 7 As shown.

[0043] In some embodiments, the initial frame 20 includes a copper alloy frame body and a metal plating layer covering the surface of the copper alloy frame body.

[0044] In some embodiments, before mounting the plurality of chips 50 onto the plurality of frame units respectively, the following steps are further included: The initial frame 20 is attached to an adhesive tape 30. The initial frame 20 includes multiple frame units, each frame unit including a base island 21 and pins 22 located around the base island 21. The pins 22 of adjacent frame units are interconnected. The recess 31 is located between the pins 22 of two adjacent frame units that are connected. Figure 4 As shown.

[0045] For example, the initial frame 20 is a PPF (Pre-Plated Frame), which includes a copper alloy frame body and a metal plating layer covering the surface of the copper alloy frame body. The metal plating layer is any one or a combination of two or more of nickel, palladium, gold, and tin plating. By providing the metal plating layer on the surface of the copper alloy frame body, the solderability of the initial frame 20 is improved. The initial frame 20 includes a front and a back side that are relatively distributed, and in a direction parallel to the front side of the initial frame 20 (e.g., ...). Figure 2 The initial frame 20 comprises a plurality of frame units arranged in a two-dimensional array, wherein both the first direction D1 and the second direction D2 are parallel to the front surface of the initial frame 20, and the first direction D1 intersects the second direction D2 perpendicularly. Each frame unit includes a base island 21 and a pad area distributed around the outer periphery of the base island 21, the pad area having a plurality of pins 22. In the initial frame 20, the pins 22 of adjacent frame units are connected, and adjacent frame units are subsequently separated by a cutting process. In one example, the initial frame 20 is a 6x6BD 40-pin PPF frame.

[0046] The back surface of the initial frame 20 has a plurality of recesses 31 formed by a chemical etching process or a physical stamping process. The recesses 31 are located at least between the pad areas of two adjacent frame units 20, for example, between the pins 22 connecting two adjacent frame units. Figure 4As shown. The recess 31 serves two purposes: firstly, it increases the contact area between the solder and the initial frame 20, thereby improving the soldering strength; secondly, the recess 31 guides solder flow and improves solder wetting performance. The recess 31 extends from the back side of the initial frame 20 along a third direction into the interior of the initial frame 20, and the depth of the recess 31 (e.g., the depth of the recess 31 along the third direction D3) is less than the thickness of the initial frame 20 (e.g., the thickness of the initial frame 20 along the third direction D3), meaning that the recess 31 does not penetrate the initial frame 20 along the third direction D3. The third direction D3 intersects the front side of the initial frame 20 perpendicularly. The specific depth and width of the recess 31 can be set according to packaging requirements. When the recess 31 is formed, metal traces, such as copper traces, remain within the recess 31. The presence of these metal traces can lead to the generation of metal burrs, such as copper burrs, during subsequent cutting processes, thus affecting the performance of the semiconductor device. However, due to the small size of the recess 31, the amount of metal traces remaining in the recess 31 is small and difficult to remove by cleaning process.

[0047] In some embodiments, the material of the tape 30 can be one or more of high-temperature resistant polymers such as polyimide, polyetherketone, and polyetheretherketone. Before attaching the initial frame 20 to the tape 30, the appearance of the initial frame 20 can be inspected in advance to ensure that the initial frame 20 is free from deformation, scratches, stains, and other defects, thereby ensuring the smooth progress of subsequent processes. By attaching the initial frame 20 to the tape 30 with the back side of the initial frame 20 facing the tape 30, i.e., the back side of the initial frame 20 is in contact with the tape 30, it is possible to prevent the molding compound from overflowing into the back side of the initial frame 20 and the interior of the recess 31 during the subsequent molding process, thereby ensuring the smooth progress of subsequent processes.

[0048] In some embodiments, the specific steps of mounting a plurality of chips 50 onto a plurality of frame units and electrically connecting the frame units and the chips 50 located above them include: Multiple chips 50 are respectively mounted onto the base islands 21 of the multiple frame units, as shown in the example. Figure 5 As shown; A lead 60 is formed on the frame unit to electrically connect the chip 50 and the pin 22, such as... Figure 6 As shown.

[0049] For example, each of the chips 50 includes a functional surface and a back surface opposite the functional surface. The initial frame is mounted on the tape 30 (e.g., Figure 4(As shown) After that, multiple chips 50 are respectively mounted onto the base islands 21 of the multiple frame units, as shown. Figure 5 As shown, the functional surface of each chip 50 faces away from the base island 21. In one example, the chip 50 can be mounted onto the frame unit (e.g., at the center of the base island 21 in the frame unit) using an adhesive material such as epoxy resin adhesive. During the mounting process of the chip 50, the amount of adhesive material such as epoxy resin adhesive should be controlled to avoid overflow caused by excessive adhesive material. After the chip 50 is mounted onto the frame unit using an adhesive material such as epoxy resin adhesive, the adhesive material can be cured by heat treatment steps such as baking to ensure a firm connection between the chip 50 and the base island 21. Next, a wire 60 electrically connecting the chip 50 and the pin 22 is formed on each frame unit by a wire bonding process, such as... Figure 6 As shown. For example, a wire 60 is formed to electrically connect the pads on the functional surface of the chip 50 to the pin 22 using a copper wire bonding device. In one example, multiple chips 50 have the same structure and function. In another example, at least two chips 50 have different structures. In this specific embodiment, "multiple" refers to two or more.

[0050] After the lead wire 60 is formed, the initial frame 20, which is attached to the adhesive tape 30, is placed in a molding die, and molding compound is injected to form the initial molding layer 70 that continuously molds the initial frame 20 and the plurality of chips 50 through a molding process, such as... Figure 7 As shown. In one example, the material of the initial molding layer 70 is epoxy resin molding compound. Because the tape 30 is attached to the back of the initial frame 20 during the formation of the initial molding layer 70, the molding compound is prevented from overflowing onto the back of the initial frame 20 and into the recess 31.

[0051] Figure 8 This is a schematic diagram of the structure after removing the tape in a specific embodiment of the present invention. In some embodiments, before forming a groove extending toward the front of the initial frame 20 at the bottom and sidewalls of the recess 31, the following steps are further included: Remove the tape 30 to expose the recess 31, as follows Figure 8 As shown.

[0052] Specifically, after the initial molding layer 70 is formed, the tape 30 is removed by a film-peeling process to expose the recess 31.

[0053] Figure 9 This is a schematic diagram of the structure during laser grooving in a specific embodiment of the present invention. Figure 10This is a schematic diagram of the structure after the trench is formed in a specific embodiment of the present invention. Figure 11 This is a physical image of the object after the grooves have been formed according to a specific embodiment of the present invention. Figure 9 The solid arrows in the diagram indicate the direction of laser transmission in the laser grooving process. In some embodiments, the specific steps of forming a groove 100 extending toward the front of the initial frame 20 at the bottom and sidewalls of the recess 31 include: The groove 100 is formed on the bottom and sidewall of the recess 31 from the back of the initial frame 20 using a laser grooving process.

[0054] Specifically, after removing the adhesive tape 30, a laser processing device is used to perform laser grooving according to the cutting path (i.e., the path along which the encapsulation structure is subsequently cut by a cutting blade to form an independent encapsulation device). For example, the position of the laser emitted by the laser processing device directed onto the initial frame 20 is adjusted according to the cutting path. Starting from the back of the initial frame 20, laser grooving is performed to form the groove 100 on the bottom of the recess 31 along the third direction D3 and on the sidewall along the second direction D2. See [link to documentation]. Figure 9 , Figure 10 and Figure 11 .

[0055] In this specific embodiment, after removing the adhesive tape 30, the groove 100 is formed on the bottom and sidewalls of the recess 31 using the laser grooving process. Because the laser grooving process is highly precise, it can accurately form the groove 100 on the relatively small bottom and sidewalls of the recess 31, thereby reducing the process difficulty of grooving the bottom and sidewalls of the recess 31 and accurately controlling the dimensions of the groove 100 (e.g., the depth and width of the groove 100). This further improves the cutting quality of subsequent monomerization processes and enhances the reliability of the QFN packaged device. Furthermore, since the laser grooving process is a non-contact grooving process, burrs are avoided during the formation of the groove 100, further ensuring the performance of the subsequently formed QFN packaged device. The bottom of the recess 31 refers to the end of the recess 31 facing the front of the initial frame 20.

[0056] In some embodiments, the initial frame 20 has a cutting groove; the specific steps of forming the groove 100 on the bottom and sidewall of the recess 31 from the back of the initial frame 20 using a laser grooving process include: A positioning mark is formed on the back side of the initial frame 20; The laser used in the laser grooving process is aligned with the cutting path by the positioning mark.

[0057] Specifically, since the packaging structure is subsequently monolithized (i.e., dicing) along the dicing path to form multiple independent QFN packaged devices, the trench 100 is located on the dicing path of the subsequent dicing blade cutting the packaging structure. Therefore, by forming the positioning mark on the back of the initial frame 20, it is easier to align the laser used in the laser grooving process with the dicing path through the positioning mark, which further simplifies the difficulty of the laser grooving process and improves the accuracy of the position of the trench 100 formed by the laser grooving process.

[0058] In other embodiments, instead of forming a positioning mark on the back of the initial frame 20, the position of the recess 31 can be determined by a positioning device such as a vision sensor, and then the laser grooving process can be performed at the determined position. This eliminates the need to form a positioning mark on the back of the initial frame 20 and avoids occupying the area of ​​the back of the initial frame 20.

[0059] In some embodiments, the specific steps of forming the groove 100 on the bottom and sidewall of the recess 31 using a laser grooving process from the back of the initial frame 20 include: While using a laser to remove the plastic sealant overflow generated by the plastic sealing process, the laser is used to form the groove 100 on the bottom and sidewall of the recess 31.

[0060] Specifically, during the molding process of forming the initial molding layer 70 that continuously encapsulates multiple chips 50 and leads 60, even when the initial frame 20 is attached to the adhesive tape 30, some molding compound may still overflow onto the back of the initial frame 20 and into the recess 31, forming molding overflow. The presence of this molding overflow can affect subsequent processes. Therefore, after the molding process is completed, a laser is needed to remove the molding overflow to avoid impacting subsequent processes (such as the subsequent individualization process of cutting the package structure to form the QFN packaged device). In one example, the specific steps for removing the molding overflow using a laser include: scanning the back of the initial frame 20 with the laser along a preset path; the laser energy acts on the molding overflow to completely vaporize or melt it away, ensuring the flatness of the back of the initial frame 20. In this specific embodiment, while using the laser to remove the molding overflow, the scanning path of the laser can be adjusted so that the process of removing the molding overflow is performed simultaneously with the process of forming the groove 100 on the bottom and sidewall of the recess 31. That is, the laser grooving process in the recess 31 is integrated with the molding overflow removal process after the molding process. Therefore, no new process equipment or new process steps are required, and there is no additional production capacity loss. This helps to reduce the manufacturing cost of the QFN packaged device while improving the manufacturing yield and production rate of the QFN packaged device.

[0061] In other embodiments, the specific steps of forming the groove 100 on the bottom and sidewalls of the recess 31 using a laser grooving process from the back of the initial frame 20 include: After removing the plastic sealant overflow generated by the plastic sealing process using a laser, the groove 100 is formed on the bottom and sidewalls of the recess 31 using the laser.

[0062] Specifically, since the laser parameters required for the laser grooving process are different from those required for the plastic sealant removal process, and the location of the laser grooving process is different from the location of the plastic sealant on the back of the initial frame 20, in order to ensure the accuracy of the size and position of the groove 100 formed by the laser grooving process while ensuring the removal of the plastic sealant, after removing the plastic sealant generated by the plastic sealant process with a laser, the groove 100 can be formed on the bottom and sidewall of the recess 31 using the laser with adjusted parameters.

[0063] In some other embodiments, the specific steps of forming the groove 100 on the bottom and sidewalls of the recess 31 using a laser grooving process from the back of the initial frame 20 include: After forming the groove 100 on the bottom and sidewalls of the recess 31 using a laser, the laser is used to remove the plastic sealant overflow generated by the molding process.

[0064] Specifically, since the laser parameters required for the laser grooving process are different from those required for the plastic sealant removal process, and the location of the laser grooving process is different from the location of the plastic sealant on the back of the initial frame 20, in order to ensure the accuracy of the size and position of the groove 100 formed by the laser grooving process while ensuring the removal of the plastic sealant, the plastic sealant generated by the plastic sealant process can be removed by the laser with adjusted parameters after the groove 100 is formed on the bottom and sidewall of the recess 31 using a laser.

[0065] In some embodiments, the specific steps of forming the groove 100 on the bottom and sidewall of the recess 31 using a laser grooving process from the back of the initial frame 20 include: The laser grooving process is used to form two grooves 100 symmetrically distributed about the center of the recess 31 on the bottom and sidewall of the recess 31, as shown in the example. Figure 10 and Figure 11 As shown.

[0066] Specifically, the laser grooving process forms two grooves 100 symmetrically distributed about the center of each recess 31. Each groove 100 is distributed on part of the bottom and part of the sidewall of the recess 31. In the subsequent process of cutting the packaging structure with the cutting blade, the two opposite edges of the cutting blade are respectively located in the two grooves 100 in the same recess 31. This ensures that the two opposite edges of the cutting blade will not come into contact with the metal traces in the recess 31 during the cutting process, fundamentally avoiding the generation of metal burrs and further ensuring the cutting quality. Furthermore, since only two grooves 100 symmetrically distributed about the center of the recess 31 need to be formed on the bottom and sidewall of the recess 31, so that the opposite edges of the cutting blade are respectively located in the two grooves 100 within the same recess 31, it is not necessary to form large-sized laser grooves on the entire bottom and sidewall of the recess 31. This allows for a corresponding reduction in the width of the grooves 100, eliminating the need to form large, wide grooves. This not only improves the manufacturing efficiency of the QFN packaged device but also avoids the problem of particulate contamination caused by excessively large groove sizes. Figure 11 The red dashed box in the figure represents the relative positional relationship between the cutting blade, the recess 31, and the groove 100 during the cutting process of the package structure.

[0067] In other embodiments, depending on actual needs, such as the positional distribution of the metal traces within the recess 31 and the cutting path of the subsequent cutting blade, the laser grooving process can be used to form a groove 100 that is only distributed on the bottom and one side wall of the recess 31, so as to improve the efficiency of laser grooving while reducing metal burrs.

[0068] In some other embodiments, the specific steps of forming the groove 100 on the bottom and sidewalls of the recess 31 using a laser grooving process from the back of the initial frame 20 include: The laser grooving process is used to form multiple grooves 100 in the recess 31. At least two of the grooves 100 distributed on the bottom and sidewall of the recess 31 are symmetrical about the center of the recess 31. This not only avoids the generation of metal burrs when the cutting process is carried out by the cutting blade, but also helps to improve the cutting efficiency of the subsequent cutting blade.

[0069] In some embodiments, the specific steps of forming the groove 100 on the bottom and sidewall of the recess 31 using a laser grooving process from the back of the initial frame 20 include: The parameters of the laser grooving process are adjusted so that the depth of the groove 100 is less than the thickness of the remaining initial frame 20 at the bottom and sidewall of the recess 31.

[0070] In some embodiments, metallic traces remain in the recess 31; the specific steps of forming the groove 100 on the bottom and sidewalls of the recess 31 using a laser grooving process from the back of the initial frame 20 include: Adjust the parameters of the laser grooving process so that the depth of the groove 100 is equal to the thickness of the metal trace.

[0071] Specifically, the depth of the groove 100 formed by the laser grooving process should not be too shallow; otherwise, the remaining metal traces will still contact the cutting blade, leading to the generation of metal burrs and metal scratches, and the improvement effect of metal burrs will not be significant. The depth of the groove 100 should also not be too deep; otherwise, it may damage the overall structural stability and strength of the initial frame. This specific embodiment adjusts the parameters of the laser grooving process, such as the power of the laser used and the number of laser scans, so that the depth of the groove 100 is equal to the thickness of the metal traces. This effectively avoids the generation of metal burrs and metal scratches in the recess 31 during subsequent cutting processes, and also avoids affecting the overall structural stability and strength of the initial frame 20. The thickness of the metal traces can be obtained through sampling analysis, statistical analysis of historical data, or measurement after taking images of the recess 31 using a scanning electron microscope.

[0072] In one example, during the process of forming the groove 100 on the bottom and sidewall of the recess 31 using a laser grooving process, the energy of the laser used in the laser grooving process can be adjusted by calculating the thickness of the metal trace, so that the groove 100 with a depth equal to the thickness of the metal trace can be formed in one laser scan, thereby improving the efficiency of laser grooving.

[0073] In another example, during the process of forming the groove 100 on the bottom and sidewalls of the recess 31 using a laser grooving process, the laser energy of a single scan in the laser grooving process can be adjusted by calculating the thickness of the metal trace. This allows for the formation of the groove 100 with a depth equal to the thickness of the metal trace through multiple laser scans, thereby improving the accuracy of the groove 100's depth. In this specific embodiment, "multiple times" refers to two or more scans.

[0074] In some embodiments, the metal trace is a copper trace; the specific steps for adjusting the parameters of the laser grooving process include: The wavelength of the laser used in the laser grooving process is adjusted to 1064nm or 532nm.

[0075] In some embodiments, the specific steps for adjusting the parameters of the laser grooving process further include: The power of the laser used in the laser grooving process is adjusted to 5W~20W.

[0076] Specifically, the laser processing equipment can be a pulsed fiber laser. Since the metal traces are mainly copper traces, and copper traces have a high absorption rate for lasers with wavelengths of 1064nm or 532nm, this improves both the accuracy of the grooving position and the efficiency of the grooving process, while also reducing the impact of thermal effects on other areas of the initial frame 20. Setting the power of the laser used in the laser grooving process to 5W~20W avoids both insufficient power to remove the metal traces within the groove 100 and excessive power that could affect the overall strength and structural stability of the initial frame 20. Furthermore, in the process of removing the plastic sealant overflow using laser, the laser power is 8W~25W. Setting the power of the laser used in the laser grooving process to 5W~20W also facilitates the integration of the laser grooving process and the plastic sealant overflow removal process.

[0077] Figure 12 This is a schematic diagram illustrating the cutting and packaging structure in a specific embodiment of the present invention. Figure 13 This is a photograph of the actual object being cut and packaged according to a specific embodiment of the present invention. Figure 14This is a cross-sectional schematic diagram of the QFN packaged device formed in a specific embodiment of the present invention. Figure 15 This is a three-dimensional structural diagram of the QFN device formed in a specific embodiment of the present invention. Figure 16 yes Figure 15 An enlarged schematic diagram of the area within the dashed box. In some embodiments, the specific steps of forming the groove 100 in the bottom and sidewalls of the recess 31 using a laser grooving process from the back of the initial frame 20 include: The parameters of the laser grooving process are adjusted so that the sum of the distance D between the two grooves 100 and the width W of the two grooves 100 is greater than the thickness of the cutting blade 120. The cutting blade 120 is used to cut the packaging structure to form multiple independent QFN packaged devices, such as... Figure 11 , Figure 12 and Figure 13 As shown.

[0078] For example, each of the recesses 31 has two grooves 100 symmetrically distributed about the center of the recess 31 at its bottom and sidewalls, and the width of each groove 100 along the first direction D1 is W. The distance between the two grooves 100 in the recess 31 along the first direction D1 is D (e.g., the distance between the edges of the two grooves 100 that are close to each other along the first direction D1 is D). The sum of the distance D between the two grooves 100 and the width W of the two grooves 100 is 2W+D. The thickness of the cutting blade 120 is T (e.g., the thickness of the cutting blade 120 along the first direction D1 is T). By making the sum of the distance D between the two grooves 100 and the width W of the two grooves 100 greater than the thickness of the cutting blade 120, i.e., (2W+D) > T, during the process of the cutting blade 120 cutting the packaging structure along the cutting path, the two edges of the cutting blade 120 that are relatively distributed along the first direction D1 are respectively located in the two grooves 100. Figure 13 The diagram shows the cutting path 130 of the cutting blade 120 cutting the package structure along the cutting channel, thereby preventing the opposite edges of the cutting blade 120 from contacting the edges of the groove 100, further avoiding the generation of metal burrs and metal scratches. Furthermore, by providing two grooves 100 symmetrically distributed about the center of the recess 31, the opposite edges of the cutting blade 120 along the first direction D1 are respectively located within the two grooves 100, which also facilitates the alignment of the cutting blade 120 with the grooves 100, thereby further reducing the difficulty of the QFN package device manufacturing process.

[0079] In some embodiments, the specific steps of adjusting the parameters of the laser grooving process so that the sum of the distance between the two grooves 100 and the width of the two grooves 100 is greater than the thickness of the cutting blade include: Adjust the positions of the two grooves 100 and the width of each groove 100 in the laser grooving process so that the thickness of the cutting blade 120 is greater than the distance D between the two grooves 100 and less than the sum of the distance between the two grooves 100 and the width W of the two grooves 100.

[0080] For example, by adjusting the positions of the two grooves 100 and the width of each groove 100 in the laser grooving process, the thickness of the cutting blade 120 is made greater than the distance D between the two grooves 100 and less than the sum of the distance between the two grooves 100 and the width W of the two grooves 100, i.e., D < T < (2W + D). This ensures that during the process of the cutting blade 120 cutting the packaging structure along the cutting path, the two relatively distributed edges of the cutting blade 120 along the first direction D1 fall inside the two grooves 100 respectively (without contacting the edge of each groove 100), that is, the two relatively distributed edges of the cutting blade 120 are confined within the grooves 100, avoiding contact between the cutting blade 120 and the bottom and sidewalls of the grooves 100. It also avoids the grooves 100 being too large, which would affect the overall structural stability of the initial frame 20.

[0081] In some embodiments, the specific steps of cutting the packaging structure to form multiple independent QFN packaged devices include: The package structure is cut along the cutting path using a cutting blade 120, with the cutting blade 120 at least partially located within the trench 100, to form a plurality of independent QFN package devices.

[0082] In some embodiments, the specific steps of cutting the packaging structure along the cutting path using a cutting blade 120, wherein the cutting blade 120 is at least partially located within the trench 100, include: The cutting blade 120 is aligned with the cutting path by means of the positioning mark, such that the cutting blade 120 is at least partially located within the groove 100.

[0083] Specifically, since the laser beam of the laser processing equipment is aligned with the groove position in the recess 31 by the positioning mark during the formation of the groove 100 through the laser grooving process, the alignment of the cutting blade 120 with the groove 100 can be achieved by aligning the positioning mark on the back of the initial frame 20 with the cutting path, thereby simplifying the alignment operation of the cutting blade 120 with the groove 100 and helping to further improve the cutting quality of the individualization process.

[0084] In one example, the cutting blade 120 can be a diamond cutting blade. Because the edge of the cutting blade 120 is confined within the groove 100 and does not contact the edge of the groove 100 facing the pin 22 during the cutting of the package structure, the cutting blade 120 avoids squeezing the metal trace, thus preventing metal burrs and scratches from occurring after cutting.

[0085] After cutting the packaging structure, multiple independent QFN packaged devices are formed, such as... Figure 14 , Figure 15 and Figure 16 As shown. Each of the QFN packaged devices includes the frame unit and the package unit above it. The frame unit includes the base island 21 and a plurality of pins 22 distributed around the outer periphery of the base island 21. The package unit includes the chip 50 mounted on the front side of the base island 21, the leads 60 electrically connecting the chip 50 and the leads 22, and the molding compound 140 encapsulating the chip 50 and the leads 60 (i.e., the initial molding compound 70 is divided into a plurality of independent molding compounds 140 by the cutting process of the dicing blade 120). The back edge of the frame unit of each QFN packaged device has a notch 150, the notch 150 including a first notch 141 and a second notch 142 that are interconnected, the second notch 142 being located on the side of the first notch 141 near the back edge of the frame unit. The first notch 141 is formed by the recess 31 remaining after the cutting blade 12 cuts the packaging structure along the cutting channel, and the second notch 142 is formed by the groove 100 remaining after the cutting blade 120 cuts the packaging structure along the cutting channel.

[0086] This specific embodiment also provides a QFN packaged device. The QFN packaged device can be adopted as follows: Figures 1-16 The QFN packaged device shown is formed using a method for forming the QFN packaged device. The structure of the QFN packaged device can be found in [reference needed]. Figure 14 , Figure 15 and Figure 16 .like Figures 1-16 As shown, the QFN packaged device includes: A frame unit includes a front and a back side that are distributed opposite to each other. The back side edge of the frame unit has a notch 150. The notch 150 includes a first notch 141 and a second notch 142 that are interconnected. The second notch 142 is located on the side of the first notch 141 that is close to the back side edge of the frame unit. The encapsulation unit is located on the front side of the frame unit and is electrically connected to the frame unit.

[0087] Specifically, the QFN packaged device includes the frame unit and the package unit located on the frame unit. The frame unit includes the base island 21 and a pad area distributed around the outer periphery of the base island 21, the pad area having a plurality of pins 22. The package unit includes a chip 50 mounted on the front side of the base island 21, leads 60 electrically connecting the chip 50 and the pins 22, and a molding compound 140 encapsulating the chip 50 and the leads 60. Each chip 50 includes a functional side and a back side opposite to the functional side, the functional side of which has pads. The functional side of each chip 50 faces away from the base island 21. One end of the lead 60 is electrically connected to the pad on the functional side of the chip 50, and the other end is electrically connected to the pin 22. In one example, the chip 50 can be mounted on the frame unit (e.g., at the center of the base island 21 in the frame unit) using an adhesive material such as epoxy resin adhesive. In one example, the material of the molding compound 140 is epoxy resin molding compound. In this specific embodiment, "multiple" refers to two or more.

[0088] The back side of the frame unit has the notch 150, which includes a first notch 141 recessed from the back side of the frame unit along a third direction D3 toward the front side of the frame unit, and a second notch 142 located on the side of the first notch 141, with the first notch 141 and the second notch 142 communicating. The third direction D3 intersects perpendicularly with the front side of the frame unit. The first notch 141 is cut along the cutting path of the packaging structure by a chemical etching process or a physical stamping process combined with a subsequent dicing blade 120 (see...). Figure 12The first notch 141 is formed as part of the recess 31, and the recess 31 is formed by chemical etching or physical stamping. The recess 31 serves two purposes: firstly, it increases the contact area between the solder and the initial frame 20 (which is cut to form the frame unit), thereby improving solder strength; secondly, it guides solder flow and improves solder wetting performance. In one example, the second notch 142 is formed before the cutting blade 120 cuts the package structure by creating a groove 100 on the bottom and sidewalls of the recess 31 using a grooving process (e.g., laser grooving), and then the initial frame 20 is cut by the cutting blade 120; that is, the second notch 142 is part of the groove 100. The edges of the second notch 142 in the frame unit (e.g., the sidewall of the second notch 142 along the first direction D1) are smooth, without metal burrs or scratches, thus significantly improving the performance of the QFN package device.

[0089] In some embodiments, a metal trace remains within the notch 150, and the metal trace has a flat cut edge.

[0090] Specifically, when the recess 31 is formed, metal traces, such as copper traces, remain within it. The presence of these metal traces can cause metal burrs, such as copper burrs, during subsequent cutting processes, thus affecting the performance of the semiconductor device. However, due to the small size of the recess 31, the amount of metal traces remaining within it is small and difficult to remove through cleaning processes. In this specific embodiment, before cutting the package structure along the cutting path with the cutting blade 120 to form the independent QFN package device, a grooving process (e.g., laser grooving) is used to form the groove 100 located at the bottom and sidewalls of the recess 31. This pre-removes the source of metal burrs on the cutting path before cutting the package structure, avoiding metal burrs and metal scraping during the cutting process. This results in smooth cutting edges on the metal traces, improving the cutting quality of the unitization process and enhancing the reliability of the QFN package device. Moreover, this specific embodiment actively removes the source of metal burrs and metal scratches, rather than removing metal burrs through post-cutting processes of the package structure. This helps to simplify the manufacturing process of the QFN packaged device and improve the manufacturing efficiency of the QFN packaged device.

[0091] In some embodiments, the frame unit includes a base island 21 and pins 22 located around the base island 21, and the packaging unit includes a chip 50 mounted on the base island 21, leads 60 electrically connecting the chip 50 and the leads 22, and a molding layer 140 molding the chip 50 and the leads 60. The notch 150 is located along the first direction D1 on the side of the pin 22 opposite to the base island 21.

[0092] In some embodiments, the frame unit includes a copper alloy frame body and a metal plating layer covering the surface of the copper alloy frame body.

[0093] Specifically, the frame unit is a PPF (Pre-Plated Frame), which includes a copper alloy frame body and a metal plating layer covering the surface of the copper alloy frame body. The metal plating layer is any one or a combination of two or more of nickel, palladium, gold, and tin plating. By applying the metal plating layer to the surface of the copper alloy frame body, the weldability of the frame unit is improved.

[0094] In some embodiments, the maximum depth of the notch 150 is less than the thickness of the pin 22.

[0095] Specifically, since the notch 150 includes a first notch 141 and a second notch 142 that are interconnected, and the second notch 142 is located on the side of the first notch 141 near the back edge of the frame unit, the maximum depth of the notch 150 refers to the depth of the second notch 142 (e.g., the depth of the second notch 142 along the third direction D3). The first notch 141 is formed after the dicing blade 120 cuts the packaging structure along the cutting path. The second notch 142 is formed before the dicing blade 120 cuts the packaging structure by forming the groove 100 at the bottom and sidewall of the recess 31 through a grooving process (e.g., laser grooving), and then by cutting the initial frame 20 along the cutting path with the dicing blade 120. The maximum depth of the notch 150 is less than the thickness of the frame unit, that is, the depth of the groove 100 is less than the thickness of the initial frame 20. This specific embodiment ensures that the depth of the groove 100 is less than the thickness of the initial frame 20, thereby ensuring that the metal traces in the groove 100 are completely removed while avoiding any impact on the overall strength and structural stability of the initial frame 20.

[0096] In some embodiments, the maximum depth of the notch 150 is 1 / 3 to 5 / 6 of the thickness of the pin 22.

[0097] In some embodiments, the sidewall of the second notch 142 has laser cutting marks.

[0098] Specifically, by employing a laser grooving process to form the groove 100 on the bottom and sidewalls of the recess 31, after the packaging structure is cut with the cutting blade 120 to form the independent QFN packaged device, the sidewalls of the second notch 142 formed by cutting the groove 100 will have laser cutting marks. Forming the groove 100 on the bottom and sidewalls of the recess 31 using the laser grooving process is precise, allowing for accurate formation of the groove 100 on the relatively small bottom and sidewalls of the recess 31. This helps reduce the difficulty of grooving the bottom and sidewalls of the recess 31 and allows for precise control of the dimensions of the groove 100 (e.g., the depth and width of the groove 100), thereby further improving the cutting quality of subsequent unitization processes and further enhancing the reliability of the QFN packaged device. Moreover, since the laser grooving process is a non-contact grooving process, burrs can be avoided during the formation of the groove 100, thereby further ensuring the performance of the QFN packaged device formed subsequently.

[0099] The laser grooving process can be performed simultaneously with the process of removing the plastic overflow generated during the molding process; or, the laser grooving process can be performed after the process of removing the plastic overflow generated during the molding process; or, the laser grooving process can be performed before the process of removing the plastic overflow generated during the molding process. The plastic overflow refers to the plastic material that partially overflows onto the back of the initial frame and into the recess 31 during the process of forming the initial molding layer 70 that continuously encapsulates multiple chips 50 and leads 60 using the molding process. Using the same laser processing equipment to perform the plastic overflow removal process and the laser grooving process eliminates the need for additional process equipment and steps, resulting in no additional production capacity loss. This helps to reduce the manufacturing cost of the QFN packaged device while improving its manufacturing yield and productivity.

[0100] In some embodiments, the width of the second notch 142 along the second direction D2 is greater than the width of the first notch 141 along the second direction D2, and the second direction D2 intersects the first direction D1 perpendicularly.

[0101] Specifically, the first notch 141 is formed by the recess 31 remaining after the cutting blade 12 cuts the package structure, and the second notch 142 is formed by the groove 100 remaining after the cutting blade 120 cuts the package structure. By setting the width of the second notch 142 along the second direction D2 to be larger than the width of the first notch 141 along the second direction D2, the source of metal burrs on the cutting path is removed in advance before cutting the package structure, avoiding the generation of metal burrs and metal scratches during the cutting of the package structure, thereby improving the cutting quality of the unitization process and improving the reliability of the QFN packaged device.

[0102] In some embodiments, the width of the first notch 141 along the second direction is 1 / 4 to 2 / 3 of the width of the pin 22, and the width of the second notch 142 along the second direction is greater than 2 / 3 of the width of the pin 22.

[0103] In some embodiments, the width of the second notch 142 along the second direction is equal to the width of the pin 22.

[0104] In some embodiments, the two opposite sidewalls of the second notch 142 in the second direction are the molding layer.

[0105] Specifically, when the width of the second notch 142 along the second direction is equal to the width of the pin 22, the metal of the two opposite sidewalls of the second notch 142 in the second direction is completely removed by laser cutting to expose the encapsulation layer.

[0106] The QFN packaged device and its formation method provided in this specific embodiment first form grooves extending towards the front of the initial frame on the recessed bottom and sidewalls of the back of the initial frame before cutting the package structure. Then, the package structure is cut to form multiple independent QFN packaged devices. This removes the source of metal burrs on the cutting path before cutting the package structure, avoiding the generation of metal burrs and metal scratches during the cutting process. This improves the cutting quality of the unitization process and enhances the reliability of the QFN packaged device. Moreover, this specific embodiment actively removes the source of metal burrs and metal scratches, rather than removing metal burrs through post-cutting processes, which helps simplify the manufacturing process of the QFN packaged device and improve its manufacturing efficiency.

[0107] Some embodiments of this specific implementation integrate the grooving process within the recess with the adhesive removal process after molding. The laser equipment used in the adhesive removal process can be used to groove the bottom and sidewalls of the recess, thus eliminating the need for additional process equipment and steps. This is compatible with existing QFN package device manufacturing processes and flows, with no additional production capacity loss. Consequently, it helps to reduce the manufacturing cost of the QFN package device while improving its manufacturing yield and productivity.

[0108] It should be noted that the terms "comprising" and "having," and their variations, used in this invention document are intended to cover non-exclusive inclusion. The terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence, unless explicitly indicated by the context; it should be understood that such use of data can be interchanged where appropriate. The term "one or more" depends at least in part on the context and can be used to describe features, structures, or characteristics in a singular sense, or in a plural sense to describe combinations of features, structures, or characteristics. The term "based on" can be understood as not necessarily intended to express an exclusive set of factors, but can instead, also at least in part on the context, allow for the presence of other factors that are not necessarily explicitly described. Furthermore, embodiments and features in embodiments of this invention can be combined with each other without conflict. In addition, descriptions of well-known components and technologies have been omitted in the above description to avoid unnecessarily obscuring the concepts of this invention. In the various embodiments described above, each embodiment focuses on its differences from other embodiments; similar / identical parts between embodiments can be referred to mutually.

[0109] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for forming a QFN packaged device, characterized in that, Includes the following steps: A packaging structure is formed, the packaging structure including an initial frame and a plurality of initial packaging bodies located on the front side of the initial frame, the initial frame including a plurality of frame units, the initial packaging bodies including a plurality of packaging units corresponding one-to-one with the plurality of frame units, and the back side of the initial frame having at least a partial recess located between two adjacent frame units. Grooves extending toward the front of the initial frame are formed at the bottom and sidewalls of the recess; The packaging structure is cut to form multiple independent QFN packaged devices, each QFN packaged device including the frame unit and the packaging unit above it.

2. The method for forming a QFN packaged device according to claim 1, characterized in that, The specific steps involved in forming the packaging structure include: The initial frame is formed, the initial frame including a front and a back side that are distributed opposite to each other, the back side of the initial frame having a recess that is at least partially located between two adjacent frame units; Multiple chips are respectively mounted onto multiple frame units, and the frame units and the chips located on top of them are electrically connected; An initial molding layer is formed by molding the initial framework and the plurality of chips using a molding process.

3. The method of forming a QFN packaged device of claim 2, wherein, The initial frame includes a copper alloy frame body and a metal plating layer covering the surface of the copper alloy frame body.

4. The method of forming a QFN packaged device of claim 2, wherein, Before mounting multiple chips onto the multiple frame units, the following steps are also included: The initial frame is attached to an adhesive tape. The initial frame includes a plurality of frame units, each frame unit including a base island and pins located around the base island. The pins of adjacent frame units are connected to each other, and the recess is located between the pins of two adjacent frame units that are connected.

5. The method of forming a QFN packaged device of claim 4, wherein, The specific steps of mounting multiple chips onto multiple frame units and electrically connecting the frame units and the chips located on top of them include: Multiple chips are respectively mounted on the base islands of the multiple frame units; Leads that electrically connect the chip and the pins are formed on the frame unit.

6. The method of forming a QFN packaged device of claim 4, wherein, Before forming grooves extending toward the front of the initial frame at the bottom and sidewalls of the recess, the following steps are also included: Remove the tape to expose the depression.

7. The method of forming a QFN packaged device of claim 2, wherein, The specific steps of forming a groove extending toward the front of the initial frame at the bottom and sidewalls of the recess include: The grooves are formed on the bottom and sidewalls of the recess from the back of the initial frame using a laser grooving process.

8. The method of forming a QFN packaged device of claim 7, wherein, The initial frame has cutting grooves; the specific steps of forming the grooves on the bottom and sidewalls of the recess using a laser grooving process from the back of the initial frame include: A positioning mark is formed on the back side of the initial frame; The laser used in the laser grooving process is aligned with the cutting path by the positioning mark.

9. The method of forming a QFN packaged device of claim 7, wherein, The specific steps for forming the groove on the bottom and sidewalls of the recess using a laser grooving process from the back of the initial frame include: While using a laser to remove the plastic sealant overflow generated during the molding process, the laser is also used to form the grooves on the bottom and sidewalls of the recess.

10. The method of forming a QFN packaged device of claim 7, wherein, The specific steps for forming the groove on the bottom and sidewalls of the recess using a laser grooving process from the back of the initial frame include: After removing the plastic sealant overflow generated by the plastic sealing process using a laser, the groove is formed on the bottom and sidewalls of the depression using the laser.

11. The method of forming a QFN packaged device of claim 7, wherein, The specific steps for forming the groove on the bottom and sidewalls of the recess using a laser grooving process from the back of the initial frame include: The laser grooving process is used to form two grooves that are symmetrically distributed about the center of the depression on the bottom and sidewalls of the depression.

12. The method for forming a QFN packaged device according to claim 7, characterized in that, The specific steps for forming the groove in the recess from the back of the initial frame using a laser grooving process include: The parameters of the laser grooving process are adjusted so that the depth of the groove is less than the thickness of the remaining initial frame at the bottom and sidewalls of the recess.

13. The method of forming a QFN packaged device of claim 7, wherein, Metal traces remain in the recess; the specific steps for forming the groove in the recess using a laser grooving process from the back of the initial frame include: Adjust the parameters of the laser grooving process so that the depth of the groove is equal to the thickness of the metal trace.

14. The method of claim 13, wherein The metal trace is a copper trace; the specific steps for adjusting the parameters of the laser grooving process include: The wavelength of the laser used in the laser grooving process is adjusted to 1064nm or 532nm.

15. The method for forming a QFN packaged device according to claim 13, characterized in that, The specific steps for adjusting the parameters of the laser grooving process also include: The power of the laser used in the laser grooving process is adjusted to 5W~20W.

16. The method of claim 11, wherein The specific steps for forming the groove on the bottom and sidewalls of the recess using a laser grooving process from the back of the initial frame include: The parameters of the laser grooving process are adjusted so that the sum of the distance between the two grooves and the width of the two grooves is greater than the thickness of the cutting blade, which is used to cut the packaging structure to form multiple independent QFN packaged devices.

17. The method of claim 16, wherein The specific steps for adjusting the parameters of the laser grooving process so that the sum of the distance between the two grooves and the width of the two grooves is greater than the thickness of the cutting blade include: Adjust the position of the two grooves and the width of each groove in the laser grooving process so that the thickness of the cutting blade is greater than the distance between the two grooves and less than the sum of the distance between the two grooves and the width of the two grooves.

18. The method of forming a QFN packaged device of claim 8, wherein, The specific steps for cutting the packaging structure to form multiple independent QFN packaged devices include: The package structure is cut along the cutting path using a cutting blade, with the cutting blade at least partially located within the trench, to form a plurality of independent QFN package devices.

19. The method of claim 18, wherein The specific steps of cutting the packaging structure along the cutting path using a cutting blade, wherein the cutting blade is at least partially located within the trench, include: The cutting blade is aligned with the cutting channel by the positioning mark, such that the cutting blade is at least partially located within the groove.

20. A QFN packaged device, characterized by, include: A frame unit includes a front and a back side that are distributed opposite to each other. The back side edge of the frame unit has a notch. The notch includes a first notch and a second notch that are interconnected. The second notch is located on the side of the first notch near the back side edge of the frame unit. The encapsulation unit is located on the front side of the frame unit and is electrically connected to the frame unit.

21. The QFN packaged device of claim 20, wherein, Metal traces remain within the notch, and the metal traces have smooth cut edges.

22. The QFN packaged device of claim 20, wherein, The frame unit includes a base island and pins located around the base island. The packaging unit includes a chip mounted on the base island, leads electrically connecting the chip and the pins, and a molding layer that encapsulates the chip and the leads. The notch is located along the first direction on the side of the pin opposite to the base island.

23. The QFN packaged device of claim 20, wherein, The frame unit includes a copper alloy frame body and a metal plating layer covering the surface of the copper alloy frame body.

24. The QFN packaged device of claim 22, wherein, The maximum depth of the notch is less than the thickness of the pin.

25. The QFN packaged device of claim 24, wherein, The maximum depth of the notch is 1 / 3 to 5 / 6 of the pin thickness.

26. The QFN packaged device of claim 20, wherein, The sidewall of the second notch has laser cutting marks.

27. The QFN packaged device of claim 22, wherein, The width of the second gap along the second direction is greater than the width of the first gap along the second direction, and the second direction intersects the first direction perpendicularly.

28. The QFN packaged device according to claim 27, characterized in that, The width of the first notch along the second direction is 1 / 4 to 2 / 3 of the pin width, and the width of the second notch along the second direction is greater than 2 / 3 of the pin width.

29. The QFN packaged device of claim 27, wherein, The width of the second notch along the second direction is equal to the width of the pin.

30. The QFN packaged device of claim 27, wherein, The second notch has two opposite sidewalls in the second direction that form the encapsulation layer.

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