A method for packaging a hall sensor chip lead frame based on adhesive insulation

Abstract

The application relates to the technical field of integrated circuits, in particular to a Hall sensor chip lead frame packaging method based on adhesive insulation. A layer of polyimide (PI) adhesive film with high insulation strength is pre-applied on a chip mounting area of a lead frame to form an electrical isolation pad layer; then a Hall sensor chip is mounted on the adhesive film and fixed, and a metal bonding wire is used to connect the electrical lead-out end of the chip with a corresponding pin on the lead frame; the adhesive insulation structure is introduced on the lead frame to isolate the Hall chip from a high-voltage current conductor; the Hall chip is attached to the adhesive film through a film isolation gasket, so that the layout of "magnetic proximity and electrical distance" is realized; the chip and the current conductor have a very small magnetic spacing but sufficient electrical insulation. The packaging method fully utilizes existing lead frame stamping, film mounting, wire welding and plastic sealing processes, guarantees compact structure and controllable process, and is suitable for batch manufacturing of Hall current sensors.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, specifically to a method for packaging Hall sensor chip lead frame based on adhesive insulation. Background Technology

[0002] Hall effect sensors are widely used in current detection and position sensing because they can sense the magnetic field generated by current. However, traditional Hall effect chip leadframe packaging methods are insufficient in meeting the requirements for high insulation withstand voltage and high magnetic sensitivity. To prevent high-voltage breakdown, chip design experts in this field add insulation measures between the chip and the current conductor of the leadframe by impregnating and curing insulating adhesive onto the leadframe to improve insulation.

[0003] However, ordinary insulating adhesives have poor thermal and electrical conductivity (e.g., low silver content), which can affect chip heat dissipation and potentially reduce device lifespan. Furthermore, while increasing the insulation layer improves voltage withstand, it also moves the Hall element away from current conductors, weakening magnetic field coupling and reducing sensitivity.

[0004] In addition, chip experts in the field, when considering the sensitivity of leadframe packaging solutions, will try to minimize the distance between the chip and the conductor or adopt special structures: for example, some products stack multiple layers of adhesive between the chip and the built-in conductor to improve the internal withstand voltage, but the resulting distance will inevitably reduce the magnetic induction intensity, making it difficult to simultaneously achieve the high insulation and high sensitivity of the aforementioned products.

[0005] Therefore, there is an urgent need to design a lead frame packaging method for Hall sensor chips based on adhesive insulation to solve the aforementioned compatibility problem. Summary of the Invention

[0006] The purpose of this invention is to provide a method for packaging Hall sensor chip lead frame based on adhesive insulation to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] The method for packaging Hall sensor chip lead frame based on adhesive insulation includes the following steps:

[0009] Step S1: Design the lead frame according to the current and insulation requirements of the Hall sensor chip;

[0010] Step S2: Place the cut polyimide film onto the chip mounting area of ​​the lead frame;

[0011] Step S3: Mount the Hall sensor chip onto the chip mounting area covered by the polyimide film;

[0012] Step S4: Perform gold wire bonding and molding encapsulation on the lead frame prepared in step S3.

[0013] The above technical solution has the following technical effects:

[0014] The overall solution of this application is to pre-apply a layer of high-insulation-strength polyimide (PI) film to the chip mounting area of ​​the lead frame to form an electrical isolation pad; then, the Hall sensor chip is mounted on the film and fixed, and the electrical leads of the chip are connected to the corresponding pins on the lead frame using metal bonding wires.

[0015] In its implementation, this invention introduces an adhesive insulating structure onto the lead frame to isolate the Hall chip from the high-voltage current conductor. The Hall chip is attached to it using a thin-film insulating pad, achieving a "magnetically close but electrically distant" arrangement: the chip and the current conductor maintain a very small magnetic distance while having sufficient electrical insulation. This achieves both high insulation and high sensitivity.

[0016] As a further improvement to the Hall sensor chip lead frame packaging method based on adhesive insulation of this application, the lead frame designed in step S1 includes a chip mounting area and current path leads. A partially flattened area is reserved in the chip mounting area to receive the polyimide film and the Hall sensor chip.

[0017] As a further improvement to the Hall sensor chip lead frame packaging method based on adhesive insulation of this application, in step S1, deburring and chamfering are performed on the corners or steps of the primary conductor in the chip mounting area, and the length of the vertical burrs is controlled within a specified value.

[0018] The method for measuring vertical burrs is microscopic inspection.

[0019] As a further improvement to the Hall sensor chip lead frame packaging method based on adhesive insulation of this application, in step S3, the sensing surface of the Hall sensor chip faces the current lead side of the lead frame, a layer of non-conductive thermosetting adhesive is applied to the back of the Hall sensor chip, and the Hall sensor chip is fixedly attached to the polyimide film by non-conductive thermosetting adhesive.

[0020] As a further improvement to the Hall sensor chip lead frame packaging method based on adhesive insulation of this application, the back of the Hall sensor chip is attached to the surface of a polyimide film, the attachment pressure is 0.5MPa, and the heating curing temperature is controlled at 80°C for 30 minutes.

[0021] As a further improvement to the Hall sensor chip lead frame packaging method based on adhesive insulation of this application, the lead frame is made of copper material with a thickness of 0.3mm, the chip mounting area size is 15mm×15mm, and the current lead width is 2mm.

[0022] As a further improvement to the Hall sensor chip lead frame packaging method based on adhesive insulation in this application, the polyimide film has a thickness of 50μm, a withstand voltage of ≥200V / mm, and a temperature resistance of ≥260℃.

[0023] As a further improvement to the Hall sensor chip lead frame packaging method based on adhesive insulation of this application, in step S2, a polyimide film is positioned and covered on the chip mounting area surface of the lead frame by vacuum adsorption, with an adsorption pressure of 0.3 MPa and an adsorption temperature of 60°C.

[0024] As a further improvement to the Hall sensor chip lead frame packaging method based on adhesive insulation of this application, in the gold wire bonding process in step S4, the gold wire is heated and melted by a welding machine, and the temperature is controlled within the range of 350-370°C. The molten gold wire is pressed onto the welding point of the lead frame and the Hall sensor chip with a pressure of 0.5N and a time of 0.5s.

[0025] As a further improvement to the Hall sensor chip lead frame packaging method based on adhesive insulation of this application, in step S4, during the molding packaging process, the bonded lead frame is installed into the molding package, wherein the mold temperature is 80°C.

[0026] The lead frame is encapsulated using epoxy molding material at an injection pressure of 80 MPa and a temperature of 150°C. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the lead frame structure of the Hall sensor based on adhesive insulating encapsulation according to the present invention;

[0028] Figure 2 for Figure 1 A magnified view of a portion at point A;

[0029] Figure 3 This is a schematic diagram of the structure of the lead frame of the present invention after being covered with polyimide insulating film;

[0030] In the diagram: 1-lead frame; 2-polyimide film; 3-chip mounting area. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] This application understands that with the increasing intelligence of electronic devices, the safety of these devices is receiving more and more attention. Driven by this practical need, power supply technologies with sensing detection, sensing sampling, and sensing protection are becoming increasingly popular in order to automatically detect and display current and provide automatic protection and more advanced intelligent control in the event of dangerous situations such as overcurrent and overvoltage. Against this backdrop, Hall effect sensors, due to their ability to sense the magnetic field generated by current, are widely used in fields such as current detection and position sensing.

[0033] This application reveals a contradiction in the packaging methods of traditional Hall effect chips regarding the balance between high insulation withstand voltage and high magnetic sensitivity. To prevent high-voltage breakdown, insulation measures are typically required between the chip and the current conductor, such as using insulating adhesive to attach the chip to the lead frame 1. However, ordinary insulating adhesives have poor thermal and electrical conductivity, which can affect chip heat dissipation and potentially reduce device lifespan.

[0034] In existing packaging solutions, while adding a thicker insulating layer improves the withstand voltage, it also moves the Hall element away from the current conductor, weakening magnetic field coupling and reducing sensitivity. Some products use multiple adhesive layers between the chip and the built-in conductor to improve internal withstand voltage, but this approach inevitably reduces the magnetic induction intensity due to the increased distance, making it difficult to simultaneously achieve high insulation and high sensitivity. Specifically, existing packaging structures have air bubbles or gaps between the chip and the current conductor, affecting the performance and stability of the Hall sensor. Furthermore, in traditional leadframe 1 packaging, if the Hall chip is directly mounted on the metal conductor, precise control of the adhesive layer thickness and chip positioning is required; otherwise, the sensing distance between batches will be inconsistent, affecting the sensor's performance stability.

[0035] To address the technical shortcomings of the aforementioned solutions, this application improves upon existing packaging methods. Specifically, this application provides a packaging method for a Hall sensor chip lead frame 1 with adhesive insulation, comprising the following steps:

[0036] Step S1: Design lead frame 1 according to the current and insulation requirements of the Hall sensor chip;

[0037] Step S2: The cut polyimide film 2 is attached to the chip mounting area 3 of the lead frame 1;

[0038] Step S3: Mount the Hall sensor chip onto the chip mounting area 3 covered by the polyimide film 2;

[0039] Step S4: Perform gold wire bonding and molding encapsulation on the lead frame 1 prepared in step S3.

[0040] Specifically, this application designs a lead frame 1 based on the current and insulation requirements of the Hall sensor. The designed lead frame 1 includes a chip mounting area 3 and current path leads, etc. At the same time, this application reserves a coin area (partially flattened area) in the area containing the chip mounting area 3 on the lead frame 1 as a substrate for carrying the adhesive film and the chip.

[0041] Furthermore, electroplating areas are planned on the surface of the lead frame 1 pins that require bonding and soldering, and silver / gold is selectively plated on the bonding area to improve bonding performance, while other areas can be tin-plated to facilitate external soldering; furthermore, the lead frame 1 is manufactured using stamping or etching processes to ensure that the dimensional accuracy and tolerance of each lead meet the design requirements, and to control the surface finish of the lead frame 1 to avoid the presence of vertical burrs.

[0042] Through the above design, this application achieves electrical isolation between the Hall chip and the current conductor by pre-applying a layer of high-insulation-strength polyimide film to the chip mounting area 3 of the lead frame 1. This effectively solves the problems of poor heat dissipation and short device life caused by the poor thermal conductivity and electrical conductivity of the insulating adhesive in traditional packaging methods. Simultaneously, using polyimide film as an electrical isolation pad ensures sufficient electrical insulation performance without significantly affecting magnetic field induction performance, overcoming the disadvantage of weakened magnetic field coupling caused by adding a thick insulating layer in existing technologies. Furthermore, this application, through the rational design of the current path leads and magnetic flux guiding structure of the lead frame 1, enables the Hall chip to maintain a small magnetic spacing while ensuring electrical insulation, thereby achieving high-sensitivity magnetic field induction and effectively solving the problem of reduced magnetic induction intensity caused by increased distance in existing technologies. It should be noted that the current path leads and magnetic flux guiding structure of the lead frame 1 designed in this application serve the improvement of the chip mounting area 3, with the coin area (partially flattened area) assembled with the polyimide film serving as the basis for this improvement.

[0043] Furthermore, in step S2, the application of the polyimide film specifically includes the following steps:

[0044] Step S21: Select a high-voltage resistant and heat-resistant polyimide film 2 as the insulating medium;

[0045] Step S22: Cut the polyimide film 2 to the required size;

[0046] Step S23: Accurately position the cut polyimide film 2 to cover the coin area (partially flattened area) of the entire chip mounting area 3, and use appropriate pressure and temperature to firmly adhere the film to the metal surface;

[0047] Step S24: The polyimide film 2 is tightly attached to the lead frame 1 by thermosetting, so as to achieve reliable insulation of the bottom metal.

[0048] Specifically, this application reserves a coin area on the lead frame 1, which includes the chip mounting area. The coin area measures 13mm × 13mm and has a thickness of 0.2mm. The lead frame 1 is made of copper and has a thickness of 0.3mm. The chip mounting area 3 measures 15mm × 15mm, and the current lead width is 2mm. As the substrate for the polyimide film, the selected polyimide film 2 has a thickness of 50μm, a withstand voltage of ≥200V / mm, and a temperature resistance of ≥260℃. In practice, the polyimide film 2 is cut into a circle with a diameter of 15mm, with a cutting accuracy controlled within ±0.1mm. Further, the cut polyimide film 2 is positioned and covered on the surface of the coin area of ​​the lead frame 1 using vacuum adsorption, with a positioning accuracy of ±0.05mm, an adsorption pressure of 0.3MPa, and an adsorption temperature of 60℃. Specifically, the polyimide film 2 is heat-cured at 60°C for 2 hours to ensure that the film adheres tightly to the lead frame 1, and the curing temperature is controlled within the range of 50-70°C.

[0049] In this process, the adhesive layer of the polyimide film 2 is thermally cured and tightly adheres to the lead frame 1, achieving reliable insulation against the bottom metal. It is worth noting that the film lamination process in this application must ensure that the adhesive film is flat and free of bubbles, with uniform thickness, and that the edges of the film are checked for any lifting to prevent resin seepage during encapsulation. After this step, the chip mounting area of ​​the lead frame 1 is covered with an insulating medium, providing electrically isolated and controlled clearance for subsequent chip installation.

[0050] Furthermore, this application also finds that traditional Hall effect sensors consist of multiple components, resulting in a complex assembly process, numerous uncontrollable factors due to human intervention, and an inability to guarantee product consistency and stability. Simultaneously, the traditional packaging method is surface mount packaging, which features a lead frame 1 base island connected to the intermediate pin. For Hall effect current sensor chips, since the heatsink serves as the conducting loop for the current input, while the die output is soldered to the pin via wire bonding, the internal lead frame 1 base island cannot be connected to the pin. This leads to high on-resistance, a small current detection range, and a thinner encapsulation, resulting in poor reliability when large currents are applied.

[0051] Traditional Hall sensor packaging also suffers from shortcomings in terms of structural compactness and manufacturing controllability. Many early magnetic sensors used a magnetic ring (magnetic core, or magnetic collector sheet) added around the chip to amplify the magnetic field and improve sensitivity, but this increased the sensor's size and weight. This type of additional magnetic circuit structure not only makes the package bulky and the assembly process complex, but may also introduce consistency issues. For example, CN114530551A discloses a Hall sensor packaging method and a Hall sensor. This method uses a mounting process to place the magnetic collector sheet at a predetermined position on the active surface of the Hall chip, and then cures and encapsulates the mounted magnetic collector sheet. This method uses a soft magnetic material magnetic collector sheet, and the mounting process places the magnetic collector sheet at a predetermined position on the active surface of the Hall chip, replacing the current electroplating or sputtering methods. However, in actual implementation, this method may result in air bubbles or gaps between the magnetic collector sheet and the Hall chip, affecting the performance and stability of the Hall sensor.

[0052] Even without a magnetic ring, in traditional lead frame 1 packaging, if the Hall chip is directly mounted on the metal conductor, the adhesive layer thickness and chip positioning need to be precisely controlled; otherwise, the sensing distance between batches will be inconsistent, affecting the stability of sensor performance. Furthermore, if the burrs generated during the stamping process of lead frame 1 are not cleaned, they may scratch the insulation layer, leading to insulation failure.

[0053] In summary, existing technologies have significant shortcomings in terms of electrical insulation, magnetic induction sensitivity, structural compactness, and manufacturing process controllability. There is an urgent need for a new packaging method to improve these aspects and achieve Hall effect chip packaging that is both highly insulating and highly sensitive, and easy to mass-produce.

[0054] Furthermore, in step S3, the sensing surface of the Hall sensor chip faces the current lead side of the lead frame 1, and a layer of non-conductive thermosetting adhesive is applied to the back of the Hall sensor chip. The Hall sensor chip is then fixedly attached to the polyimide film 2 using this non-conductive thermosetting adhesive. The Hall sensor chip is manufactured through the following steps:

[0055] Step S31: Precisely place the Hall sensor chip (size: 12mm×12mm) on the chip area of ​​the lead frame 1, ensuring that the front of the chip faces the current lead side.

[0056] Step S32: Coat the back of the chip with a layer of non-conductive thermosetting adhesive with a thickness of 0.2 mm.

[0057] Step S33: Press the chip onto the specified position on the surface of the polyimide film 2 at a pressure of 0.5 MPa and a temperature of 80°C.

[0058] Step S34: Heat the adhesive at 80°C for 30 minutes to cure it, so that the chip is firmly attached to the adhesive film.

[0059] Step S35: Using gold wire bonding technology, connect the electrode pads on the chip to the corresponding pins on the lead frame 1. The diameter of the gold wire is 0.5mm.

[0060] Specifically, in the above-described fabrication process, the Hall sensor chip is placed on the chip area of ​​the pre-coated lead frame 1. The sensing surface of the chip faces the current lead side of the lead frame 1 (usually the front of the chip faces down, close to the current path). A layer of non-conductive thermosetting adhesive (insulating adhesive) is applied to the back of the chip, and then the chip is pressed onto the designated position on the adhesive film surface. The adhesive is cured by heating, making the chip firmly adhere to the adhesive film. Since the adhesive film itself is non-conductive, the back of the chip is completely insulated from the metal of the lead frame 1, avoiding the risk of leakage between the chip substrate and the current conductor under high voltage. During chip positioning, it is necessary to ensure that its sensitive area is exactly above the current path conductor, and the positional deviation is controlled within the design tolerance range. After curing, the Hall chip is stably fixed on the lead frame 1, with a cured adhesive film / layer between the chip and the bottom metal. The thickness of the adhesive film is determined by the thickness of the chip, thereby achieving a precise and controllable sensing distance.

[0061] Furthermore, in step S4, during the gold wire bonding process, this application uses a welding machine to heat and melt the gold wire, controlling the temperature within the range of 350-370°C. The molten gold wire is then pressed onto the bonding point between the lead frame 1 and the Hall sensor chip, with a pressure of 0.5N and a time of 0.5s. The gold wire bonding process includes the following steps:

[0062] Step S41: Heat and melt the gold wire using a welding machine, controlling the temperature within the range of 350-370℃.

[0063] Step S42: Press the molten gold wire onto the welding point with a pressure of 0.5N for 0.5s.

[0064] Step S43: After the gold wire cools down, check the reliability of the solder joint to ensure that the solder resistance is <50mΩ.

[0065] Furthermore, the gold wire bonding process and current path routing strategy of this application employs gold wire bonding (or aluminum wire bonding) technology to connect the electrode pads on the Hall sensor chip to the corresponding pins on the lead frame 1. Specifically, the Hall sensor chip includes power, ground, and signal output pads, which are connected to the pins of the lead frame 1 via gold wires to achieve electrical connection. In actual manufacturing, attention must be paid to the routing and curvature of the leads to avoid the gold wires getting too close to high-voltage, high-current leads, thus ensuring a safe insulation distance.

[0066] Specifically, regarding the current path routing strategy, the leads (i.e., the primary current path) on the lead frame 1 of this application used to carry the measured current are designed to be as close as possible to the chip's sensing area and form a wraparound / U-shaped structure. For example, the current can be introduced from one side pin, a thick copper conductor of the lead frame 1 passes under the chip, and then leads out from the other side pin, forming an approximately U-shaped current path around the Hall sensor chip. The current flowing through this way will generate a magnetic field around the chip, and most of it will pass through the sensing surface of the Hall sensor chip, achieving maximum magnetic flux coupling. This current conductor portion of the lead frame 1 is typically thicker and wider to reduce resistance and heat generation, and the magnetic field distribution can be balanced by optimizing the trace shape. After bonding is completed and the current path design is determined, the entire frame contains both the secondary circuit (Hall chip signal leads) and the primary current loop, which are electrically isolated but magnetically tightly coupled.

[0067] In step S4, during the molding and encapsulation process, the bonded leadframe 1 is placed into the molding package, where the mold temperature is 80°C; epoxy molding material is used to injection mold the leadframe 1, with an injection pressure of 80 MPa and a temperature of 150°C. The molding and encapsulation process includes the following steps:

[0068] Step S51: The bonded lead frame 1 is installed into a molded package at a mold temperature of 80°C.

[0069] Step S52: Design a plastic package above the chip sensing area to retain a window structure with a diameter of 12mm and a thickness of 0.1mm.

[0070] Step S53: Use epoxy molding compound (model: EPO-TEK 301-2) for injection molding encapsulation. The injection pressure is 80MPa and the temperature is 150℃.

[0071] Step S54: After packaging is completed, perform electrical tests on each lead pin to ensure that the insulation resistance is >100MΩ.

[0072] In this application, the lead frame 1, after chip bonding, is installed into a mold for molding and encapsulation (such as epoxy molding). During encapsulation, the coverage of the molding compound on the leads and chip under high-voltage isolation requirements must also be considered. By designing the mold cavity, while ensuring sufficient coverage and protection for the chip and leads, a "window" treatment is applied to specific areas. For example, directly above the sensing area of ​​the Hall sensor chip, a thin layer or window structure can be designed in the molding compound: that is, the molding compound is not completely filled in this area, forming a thinner package thickness than other areas, or even leaving a small air cavity. The purpose of this window design is to balance sensing performance and package integrity: the thin-film window reduces the thickness of non-magnetic material above the chip, helping to maintain effective magnetic field conduction; at the same time, the area around the window is still supported by the molding compound, ensuring the mechanical strength of the package. Furthermore, retaining the window area can also avoid stress concentration on the chip during subsequent processing (such as wire cutting and calibration testing).

[0073] In addition to the above, the lead frame 1 prepared in this application also needs to undergo electrical performance testing and cutting and shipping. Specifically, it includes the following steps:

[0074] Step 61: Curing the encapsulated lead frame 1 board at 25℃ for 2 hours.

[0075] Step 62: Measure the static bias voltage, sensitivity, and linearity using the four-probe method, with a test accuracy of ±1%. The withstand voltage insulation test voltage is 500V, and the test time is 1000 hours; no breakdown occurs.

[0076] Step 63: Use a laser cutting device to cut and separate the lead frame 1 from the carrier plate.

[0077] Step 64: Perform SMD molding on the pins at a molding temperature of 150℃.

[0078] Step 65: Inspect the appearance of the device using an automated optical inspection device. After confirming that there are no defects, proceed with packaging. To fully demonstrate the technical effects of this application, this application demonstrates some of the semi-finished products prepared in the lead frame 1.

[0079] Specifically, such as Figure 1The diagram shows a schematic of the lead frame 1 of a Hall sensor based on adhesive insulating encapsulation. It illustrates the basic structure of the lead frame 1 and the layout of the chip mounting area 3, where point A represents the chip mounting area 3 for mounting the Hall chip and the current path leads running through it. The lead frame 1 has a frame support strip connecting the pins (used for positioning before encapsulation and will be removed after encapsulation). As can be seen in the figure, the chip area of ​​the lead frame 1 is slightly larger than the Hall chip itself to provide sufficient adhesion area and insulation margin. Current leads pass through the side of this area and extend to form input / output pins for external current access. This figure demonstrates the structural feature of the lead frame 1, which serves as both a current conductor and a chip support.

[0080] Furthermore, such as Figure 2 As shown (specifically) Figure 1 (Corresponding to the area highlighted at point A), a thin polyimide film 2 covers the chip mounting area of ​​leadframe 1, its outline perfectly conforming to the metal substrate island area. The film thickness is uniform, approximately 50 μm, and as can be seen from the side in the figure, the film separates the metal leads from the chip position. The edges of the film are aligned with leadframe 1, without obstructing the surrounding pin areas used for bonding. This figure demonstrates that the polyimide film 2 effectively provides an electrical isolation layer for the subsequent chip, ensuring a safe insulating plane is formed on top even if there is a high voltage on the current conductor of leadframe 1. Simultaneously, the thickness of the film determines the distance (magnetic gap) between the Hall chip and the current leads, a dimension that is precisely controllable during manufacturing.

[0081] Furthermore, Figure 3 The schematic diagram shows the structure after the lead frame 1 is coated with polyimide insulating film. In this diagram, the lead frame 1 after pressure processing often has vertical burrs at the connection edge of the chip mounting area 3 (the area selected by the box in area B in the figure). The height of these burrs may reach 10–50 μm. If they are not removed, they can easily form local stress points, breakdown points or scratches during film bonding. In this application, chemical polishing, plasma etching, micro-polishing with a brush are used to locally deburr the area B before film bonding, which makes the contact between the polyimide film and the metal interface more uniform and the insulation more reliable.

[0082] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0083] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for packaging Hall sensor chip lead frame based on adhesive insulation, characterized in that, The steps include the following: Step S1: Design the lead frame according to the current and insulation requirements of the Hall sensor chip; Step S2: The cut polyimide film is attached to the chip mounting area of ​​the lead frame; Step S3: Mount the Hall sensor chip onto the chip mounting area covered by the polyimide film; Step S4: Perform gold wire bonding and molding encapsulation on the lead frame prepared in step S3.

2. The method for packaging Hall sensor chip lead frame based on adhesive insulation according to claim 1, characterized in that, The lead frame designed in step S1 includes a chip mounting area and current path leads. A partially flattened area is reserved in the chip mounting area to support the polyimide film and the Hall sensor chip.

3. The method for packaging Hall sensor chip lead frame based on adhesive insulation according to claim 2, characterized in that, In step S1, the chip mounting area is controlled to deburr and chamfer at the corners or steps of the primary conductor, and the length of the vertical burrs is controlled within a specified value. The method for measuring vertical burrs is microscopic inspection.

4. The method for packaging Hall sensor chip lead frame based on adhesive insulation according to claim 1, characterized in that, In step S3, the sensing surface of the Hall sensor chip faces the current lead side of the lead frame, and a layer of non-conductive thermosetting adhesive is applied to the back of the Hall sensor chip. The Hall sensor chip is then fixedly attached to the polyimide film using the non-conductive thermosetting adhesive.

5. The method for packaging Hall sensor chip lead frame based on adhesive insulation according to claim 4, characterized in that, The back of the Hall sensor chip is attached to the surface of the polyimide film at a pressure of 0.5 MPa and the curing temperature is controlled at 80°C for 30 minutes.

6. The method for packaging Hall sensor chip lead frame based on adhesive insulation according to claim 4, characterized in that, The lead frame is made of copper with a thickness of 0.3mm, the chip mounting area is 15mm×15mm in size, and the current lead is 2mm wide.

7. The method for packaging Hall sensor chip lead frame based on adhesive insulation according to claim 1, characterized in that, The polyimide film has a thickness of 50 μm, a compressive strength ≥200 V / mm, and a temperature resistance ≥260℃.

8. The method for packaging Hall sensor chip lead frame based on adhesive insulation according to claim 1, characterized in that, In step S2, the polyimide film is positioned and covered on the surface of the chip mounting area of ​​the lead frame by vacuum adsorption, with an adsorption pressure of 0.3 MPa and an adsorption temperature of 60°C.

9. The method for packaging Hall sensor chip lead frame based on adhesive insulation according to claim 1, characterized in that, In step S4, during the gold wire bonding process, the gold wire is heated and melted using a welding machine, with the temperature controlled within the range of 350-370°C. The molten gold wire is then pressed onto the welding point between the lead frame and the Hall sensor chip, with a pressure of 0.5N and a time of 0.5s.

10. The method for packaging Hall sensor chip lead frame based on adhesive insulation according to claim 1, characterized in that, In step S4, during the molding and encapsulation process, the bonded lead frame is installed into the molding package, wherein the mold temperature is 80°C. The lead frame is encapsulated using epoxy molding material at an injection pressure of 80 MPa and a temperature of 150°C.

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