A bonding fixing structure suitable for TOLL products

Abstract

The application discloses a bonding fixing structure suitable for TOLL products, which comprises a mounting seat, a pressing plate and a cushion block, a plurality of pressing fingers are detachably arranged on the pressing plate; the cushion block is fixedly arranged in a mounting groove of the mounting seat through a cushion block fixing piece and is used for supporting a lead frame in the TOLL product; for a middle bonding area of the lead frame, the cushion block forms a higher supporting surface corresponding to the middle bonding area compared with other cushion block areas; the pressing plate is detachably arranged on a top surface of the mounting seat, the pressing plate is provided with a hollow part, the lead frame is completely exposed below the hollow part, and the pressure bearing end of the pressing finger presses the lead frame through the hollow part. The application significantly improves the stability and reliability of the bonding process of the TOLL product and reduces the probability of false welding.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor packaging technology, and in particular to a bonding and fixing structure suitable for TOLL products. Background Technology

[0002] TOLL (Transistor Outline Leadless) packaging is an advanced power device packaging technology. TOLL-packaged products (referred to as TOLL products) are widely used in power devices and modules due to their compact structure, good thermal conductivity, and superior electrical performance. Wedge bonding, as one of the core processes in TOLL packaging, directly affects the performance and lifespan of the device due to its process stability and reliability. To ensure reliable interconnection between the chip and the lead frame, specialized bonding auxiliary tools are typically designed to accommodate different wire diameters and prevent uneven stress on the chip, which could lead to collapse or cracking.

[0003] In related technologies, most TOLL products use conventional pressing and support structures for bonding aids, which have certain defects when bonding large chips and thick wires. For example, uneven pressing stress in the bonding aids can cause base island collapse, and in the bonding process of multiple thick aluminum wires (referred to as thick wires), the two middle thick wires are prone to poor soldering. Utility Model Content

[0004] The main purpose of this application is to provide a bonding and fixing structure suitable for TOLL products, aiming to solve the technical problem of poor bonding quality in TOLL products.

[0005] To achieve the above objectives, this application adopts the following technical solution: A bonding and fixing structure suitable for TOLL products includes a mounting base, a pressing plate, and a pad, wherein a plurality of pressing fingers are detachably provided on the pressing plate; The pad is fixedly installed in the mounting slot of the mounting base by the pad fastener to support the lead frame in the TOLL product; for the middle bonding area of ​​the lead frame, the pad forms a higher support surface than other pad areas. The pressing plate is detachably mounted on the top surface of the mounting base. The pressing plate has a hollow section, and the lead frame is completely exposed below the hollow section. The pressure-bearing end of the pressing finger passes through the hollow section and presses down on the lead frame.

[0006] In one embodiment, other pad areas form a certain angle relative to the supporting surface.

[0007] In one embodiment, quick-installation holes are respectively provided on both sides of the short side of the pressing plate. The quick-installation holes are composed of interconnected circular holes and narrow slots, and the width of the narrow slots is smaller than the width of the circular holes. Mounting posts are provided on the top of the mounting base and on both sides parallel to the short side of the pressing plate. Each mounting post consists of a limiting head and a connecting post set at the top and bottom. The width of the limiting head is smaller than the width of the circular hole but larger than the width of the narrow groove, and the width of the connecting post is smaller than the width of the narrow groove.

[0008] In one embodiment, guide grooves are provided on both sides of the short side of the pressing plate, and the guiding direction of the guide grooves is parallel to the long side of the pressing plate; a first threaded hole is provided on the side of the guide groove away from the hollow part, so that one end of the limiting screw enters the guide groove through the first threaded hole. Guide pins are provided on the top of the mounting base and on both sides parallel to the short side of the pressing plate. The diameter of the guide pins is smaller than the width of the guide groove.

[0009] In one embodiment, a plurality of second threaded holes are provided on both sides of the long side of the top surface of the mounting base. The mounting end of the pressure finger is fixed to the corresponding second threaded hole by screws, and the pressure-bearing end of the pressure finger is pressed onto the top surface of the lead frame through the hollow part.

[0010] In one embodiment, a screw washer is provided between the pressure finger and the screw.

[0011] In one embodiment, the types of pressure fingers on the pressing plate include Y-head pressure fingers, flat-head pressure fingers, and pointed-head pressure fingers.

[0012] In one embodiment, the lead frame consists of two frame units, each frame unit having three pairs of pressure fingers on its top surface. The three pairs of pressure fingers are, in order, a pair of Y-shaped pressure fingers, a pair of flat pressure fingers, and a pair of pointed pressure fingers.

[0013] In one embodiment, an air blowing mechanism is provided on one side of the mounting base, and there is a gap between the pressing plate and the mounting base, so that the airflow blown by the air blowing mechanism sweeps the pad in the mounting base along the gap.

[0014] In one embodiment, the air blowing mechanism includes a guide seat with an air groove and a plurality of air outlet components disposed above the air groove. The air outlets of the air outlet components face the gap so that the airflow blown by the air blowing mechanism sweeps the pad in the mounting base along the gap.

[0015] One or more technical solutions proposed in this application have at least the following technical effects: This application improves the morphology of the pads and the finger structure, and introduces the principle of reverse deformation to achieve reliable bonding of large chips to thick wires, reducing chip stress and the risk of hidden cracks. Furthermore, the addition of an air-blowing function reduces the impact of foreign matter on the pad morphology, significantly improving the overall stability and reliability of the TOLL product bonding process. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the aluminum wire bonding positions of the TOLL product in this application.

[0018] Figure 2 This is an isometric view of the bonding and fixing structure of this application.

[0019] Figure 3 This is a top view of the bonding and fixing structure press plate of this application.

[0020] Figure 4 This is a schematic diagram of the pad block structure.

[0021] Figure 5 This is a front view of the bonding and fixing structure of this application.

[0022] Figure 6 This is a schematic diagram of the base island structure.

[0023] Figure 7 This is a schematic diagram of the air guide seat structure of the air blowing mechanism.

[0024] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0025] Reference numerals: 100 Mounting base, 101 Gap, 102 Mounting post, 103 Guide pin, 104 Limiting screw, 200 Pressing plate, 201 Quick-release hole, 202 Guide groove, 203 Pressing finger, 203_a Pointed pressing finger, 203_ Flat pressing finger, 203_c Y-head pressing, 204 Screw washer, 205 Screw, 206 Second threaded hole, 207 Hollow part, 208 First threaded hole, 300 Pad, 301 Pad fixing piece, 400 Lead frame, 401 Base island, 402 Base island step, 403 Pressing groove, 404 Naturally formed area, 501 Air vent component, 502 Air vent, 503 Base, 504 First mounting screw, 505 Second mounting screw, 506 Air inlet groove. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] It should be noted that in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an apparatus or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an apparatus or system. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the apparatus or system including that element. In this application, unless otherwise expressly specified and limited, the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two elements or the interaction between two elements. In this application, if descriptions refer to "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may expressly or implicitly include at least one of those features. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only on the basis that those skilled in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0028] In related technologies, most TOLL products use conventional pressing and support structures for bonding aids, which have certain defects when bonding large chips and thick wires. For example, uneven pressing stress in the bonding aids can cause base island collapse, and in the bonding process of multiple thick aluminum wires, the two middle thick wires are prone to poor soldering.

[0029] In particular, such as Figure 1 As shown, Figure 1 This is a schematic diagram of the wire bonding of TOLL products. Figure 1 During the bonding process of multiple thick aluminum wires, the two middle thick wires are prone to poor soldering, which in turn affects the bonding strength and electrical performance.

[0030] To address the aforementioned problems, this application provides a bonding and fixing structure suitable for TOLL products to improve the bonding quality of TOLL products. Specific embodiments and implementation methods are as follows: Reference Figure 2 , Figure 3 , Figure 4 and Figure 5 This embodiment proposes a bonding and fixing structure suitable for TOLL products, including a mounting base 100, a pressing plate 200, and a pad 300. Several pressure fingers 203 are detachably provided on both sides of the long side of the pressing plate 200. The pad 300 is fixedly mounted in the mounting groove of the mounting base by a pad fixing member 301, and is used to support the lead frame 400. Regarding the intermediate key and area of ​​the lead frame 400 (this area can be referred to...),... Figure 1 The pad 300 corresponds to the intermediate key and region, forming a higher support surface compared to other pad regions (see...). Figure 4 Furthermore, other pad areas form a certain angle relative to the supporting surface. The pressing plate 200 is detachably mounted on the top surface of the mounting base 100. The pressing plate 200 has a hollow portion 207. After the pressing plate 200 is mounted on the mounting base 100, the lead frame 400 is completely exposed below the hollow portion. The pressure-bearing end of the pressure finger 203 passes through the hollow portion and presses against the lead frame 400.

[0031] A base island 401 is provided on the lead frame 400. A base island step area 402 is provided on the lower surface of the base island 401. A pressing groove 403 is provided on both sides of the upper surface (chip mounting surface) of the base island 401 that are parallel to the long side of the pressing plate 200.

[0032] The short side of the pressing plate 200 is provided with quick-installation holes 201. Each quick-installation hole 201 consists of a through-hole and a narrow groove, the width of which is smaller than the width of the hole. On the top of the mounting base 100, on both sides parallel to the short side of the pressing plate 200, mounting posts 201 are provided. Each mounting post 201 consists of a limiting head and a connecting post, the width of which is smaller than the width of the hole but larger than the width of the groove, and the width of the connecting post is smaller than the width of the groove.

[0033] Guide grooves 202 are provided on both sides of the short side of the pressing plate 200, and the guiding direction of the guide grooves 202 is parallel to the long side of the pressing plate 200. A first threaded hole 208 is provided on the side of the guide groove 202 away from the hollow part, so that one end of the limiting screw 104 enters the guide groove through the first threaded hole 208. Guide pins 103 are provided on the top of the mounting base 100 on both sides parallel to the short side of the pressing plate, and the diameter of the guide pins 103 is smaller than the width of the guide groove.

[0034] The mounting base 100 has several second threaded holes 206 on both sides of its long side. The mounting end of the pressure finger 203 is fixed to the corresponding second threaded hole 206 by a screw 205. The pressure-bearing end of the pressure finger 203 is pressed onto the top surface of the lead frame 400 through the hollow part 207. A screw washer 204 is provided between the pressure finger 203 and the screw 205.

[0035] The lead frame 400 consists of two frame units. Each frame unit has three pairs of different types of pressure fingers on its top surface. The types of pressure fingers are Y-head pressure fingers 203_a, flat-head pressure fingers 203_b, and pointed-head pressure fingers 203_c, respectively.

[0036] In this embodiment, when TOLL products bond aluminum wires, there is a problem that the two thick aluminum wires in the middle are prone to poor soldering. In order to solve this problem, this embodiment has made certain improvements to the traditional pad.

[0037] For example, refer to Figure 4 The design of the pad was continuously optimized using PDCA (Plan-Do-Check-Act) and the optimal morphology of the pad was found through DOE (Design of Experiments) verification. Specifically, considering the size variation of the chip, two scale variation factors, A and B, were set. A represents the area corresponding to the bonding between the upper surface of the pad and the two thick aluminum wires in the middle of the TOLL product, and B represents the tilt angle of other areas on the upper surface of the pad relative to area A.

[0038] Using ultrasonic energy transfer efficiency during bonding, the consistency of pressing the thick aluminum wire, stress distribution of the chip at different sizes, and the rates of solder joint defects and cracks as evaluation indicators, this study tests these indicators by varying factors A and B. The goal is to find the combination that yields the highest solder joint pass rate and minimizes stress, thus obtaining the optimal morphology of the spacer. Essentially, this involves a slight pre-deformation of the spacer based on the principle of reverse deformation, ensuring more uniform pressing force on the thicker wire. Understandably, by determining the optimal combination of A and B, the study finds the best spacer morphology that ensures uniform pressing force distribution and effective ultrasonic energy transfer. This avoids solder joint defects on the thicker wire and reduces internal chip stress and crack risk, thereby improving reliability.

[0039] To further address the issue of frequent cold solder joints, refer to Figure 2 In this embodiment, the lead frame 400 of the TOLL product includes two frame units. Based on the specific lead frame structure of the TOLL product, this embodiment performs a targeted crimping finger structure design. Specifically, for each frame unit, three pairs of different types of crimping fingers are set, namely pointed crimping fingers 203_a, flat crimping fingers 203_b, and Y-shaped crimping fingers 203_c, in order to achieve effective crimping of the lead frame 400 and reduce the probability of poor soldering.

[0040] Furthermore, in this embodiment, each frame unit is provided with a corresponding base island 401. Considering the potential for overflow during the packaging process of TOLL products, this embodiment makes certain improvements to the base island structure, referring to... Figure 6 First, when arranging the base island, the upper surface of the base island carries the chip, and a base island step 402 is provided on the lower surface of the base island to prevent overflow. Second, a pressing groove 403 is also provided on the upper surface of the base island to achieve effective pressing of the pressing finger 203 onto the base island. The part of the base island that contacts the pressing finger 203 is a solid structure to avoid crushing the step part. In this embodiment, the depth of the pressing groove 403 is 0.03mm.

[0041] Understandably, this combined structure reduces the occurrence of overflow while ensuring effective bonding of the base island to the bonding structure, thus preventing the base island from collapsing.

[0042] Furthermore, considering the ease of use of the bonding and fixing structure, the pressing plate in this embodiment adopts a quick-installation and quick-release structure. Specifically, in use, the pressing plate 200 is simply installed on the top of the mounting base 100 through the quick-installation hole 201 to achieve vertical positioning of the pressing plate 100. Then, by rotating the limiting screws 104 on both sides of the pressing plate 100, the limiting screws 104 on both sides abut against the positioning pins on both sides to achieve horizontal positioning of the pressing plate 100, thereby fixing the pressing plate 202 on the mounting base 100. In addition, by adjusting the limiting screws 104, the pressing plate 100 can also be finely adjusted along its longitudinal long side to better align the pressing lead frame 400 with the pressing finger 203 and the solid pressing structure 402. Understandably, the pressure finger 203 is mainly used to effectively press the bonding points around the lead frame and / or chip. In this embodiment, the pressure finger 203, in conjunction with the cleverly designed pressing groove 403 on the base island 401, can achieve stable pressing of the base island, thereby further reducing the probability of poor soldering. In this embodiment, the pressure finger 203 is installed at the second threaded hole 206 of the pressing plate 100 by screws 205 and screw washers 204, facilitating disassembly.

[0043] Furthermore, refer to Figure 1 and Figure 7 In this embodiment, an air blowing mechanism is also provided on one side of the bonding and fixing structure. The air blowing mechanism consists of an air outlet component 501 and a guide seat with an air groove, the air groove structure being as follows: Figure 7 As shown, Figure 7The image shows a bottom view of the air guide seat. Specifically, the air guide seat is fixed to the base 503 by the first mounting screw 504. An air inlet 506 is formed between the base 503 and the air guide seat. The airflow enters the air outlet component 501 through the transverse groove of the T-shaped air guide groove and is blown out through the air outlet hole 502 of the air outlet component 501 located at the top of the air guide seat. Then, it is blown towards the fixed bonding structure through the gap 101. The air outlet component 501 is fixed to the transverse air groove position of the air guide seat by the second mounting screw 505.

[0044] The venting mechanism is mainly used to clean the surface of the pad, reduce the impact of foreign objects on the shape of the pad, and prevent abnormalities such as chip cracks.

[0045] In summary, this embodiment introduces an optimized design based on the principle of reverse deformation into the pad structure, enabling the thick aluminum wire in the middle to obtain more uniform pressing force and ultrasonic energy transfer, significantly reducing the risk of poor soldering and chip cracking. At the same time, the combination of multiple types of pressing finger structures such as pointed, flat, and Y-shaped tips further improves the pressing stability of the lead frame. The improved base island step and pressing groove design effectively avoids overflow and base island collapse problems. The quick-install and quick-release pressing plate structure improves the convenience of assembly and adjustment, and can achieve fine-tuning to ensure precise alignment. In addition, the matching air blowing mechanism can clean the surface of the pad before bonding, reducing foreign object interference.

[0046] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A bonding and fixing structure suitable for TOLL products, characterized in that, It includes a mounting base, a pressing plate, and a pad, wherein the pressing plate is detachably provided with a plurality of pressing fingers; The pad is fixedly installed in the mounting slot of the mounting base by the pad fastener, and is used to support the lead frame in the TOLL product; for the middle bonding area of ​​the lead frame, the pad forms a higher support surface than other pad areas. The pressing plate is detachably disposed on the top surface of the mounting base. The pressing plate has a hollow portion, and the lead frame is completely exposed below the hollow portion. The pressure-bearing end of the pressing finger passes through the hollow portion and presses against the lead frame.

2. The bonding and fixing structure for TOLL products according to claim 1, characterized in that, The other pad areas form a certain angle relative to the supporting surface.

3. The bonding and fixing structure for TOLL products according to claim 1, characterized in that, The short side of the pressing plate is provided with quick-installation holes, which are composed of interconnected circular holes and narrow slots. The width of the narrow slots is smaller than the width of the circular holes. Mounting posts are provided on the top of the mounting base and on both sides parallel to the short side of the pressing plate. Each mounting post consists of a limiting head and a connecting post arranged vertically. The width of the limiting head is smaller than the width of the circular hole but larger than the width of the narrow groove, and the width of the connecting post is smaller than the width of the narrow groove.

4. The bonding and fixing structure for TOLL products according to claim 3, characterized in that, The short sides of the pressing plate are respectively provided with guide grooves, and the guiding direction of the guide grooves is parallel to the long side of the pressing plate; a first threaded hole is provided on the side of the guide groove away from the hollow part, so that one end of the limiting screw enters the guide groove through the first threaded hole. Guide pins are provided on the top of the mounting base and on both sides parallel to the short side of the pressing plate, and the diameter of the guide pins is smaller than the width of the guide groove.

5. The bonding and fixing structure for TOLL products according to claim 1, characterized in that, The mounting base has several second threaded holes on both sides of its long side. The mounting end of the pressure finger is fixed to the corresponding second threaded hole by screws. The pressure-bearing end of the pressure finger is pressed against the top surface of the lead frame through the hollow part.

6. The bonding and fixing structure for TOLL products according to claim 5, characterized in that, A screw washer is provided between the pressure finger and the screw.

7. The bonding and fixing structure suitable for TOLL products according to claim 1, characterized in that, The types of pressing fingers on the pressing plate include Y-head pressing fingers, flat-head pressing fingers, and pointed-head pressing fingers.

8. The bonding and fixing structure for TOLL products according to claim 7, characterized in that, The lead frame consists of two frame units, and each frame unit has three pairs of pressure fingers on its top surface. The three pairs of pressure fingers are, in order, a pair of Y-head pressure fingers, a pair of flat-head pressure fingers, and a pair of pointed-head pressure fingers.

9. The bonding and fixing structure for TOLL products according to claim 1, characterized in that, An air blowing mechanism is provided on one side of the mounting base, and there is a gap between the pressing plate and the mounting base so that the airflow blown by the air blowing mechanism sweeps the pad in the mounting base along the gap.

10. The bonding and fixing structure for TOLL products according to claim 9, characterized in that, The air blowing mechanism includes a guide seat with an air groove and a plurality of air outlet components disposed above the air groove. The air outlet holes of the air outlet components face the gap so that the airflow blown by the air blowing mechanism sweeps the pad in the mounting base along the gap.

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