Suspended wire bonding process and tooling

Abstract

The present invention provides a suspended wire bonding process, which includes fixing a MEMS chip in a package through a suspended wire bonding tooling, performing wire bonding on the MEMS chip so that the MEMS chip is connected to the package through metal wires; after the wire bonding is completed, removing the suspended wire bonding tooling, the MEMS chip is connected to the package through metal wires and there is a gap between the bottom of the MEMS chip and the package, presenting a suspended state; using glue with a viscosity value of 14,500 cp to coat the surface where the MEMS chip is connected to the metal wire to form a protective layer, curing the protective layer under curing conditions, and the coating thickness covers the solder joints at the connection between the MEMS chip and the metal wire. The present invention realizes a suspended wire bonding process with a Young's modulus of zero, avoids the negative impact of external stress changes on the internal structure of the MEMS chip, and ensures the parameter stability of the MEMS chip in the full-temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of MEMS packaging, and particularly to a wire bonding process in suspension and the tooling therefor. Background Art

[0002] The connection between a micromachined silicon chip and a substrate is one of the most critical steps in the packaging of high-precision MEMS (Micro-Electro-Mechanical System) accelerometers. The stress and strain caused during the chip mounting process due to the mismatch of TCE (Thermal Coefficient of Expansion) between different materials will have an adverse impact on the output characteristics of the accelerometer sensor. Among them, the Young's modulus and the thickness of the adhesive are the most important factors affecting the stress and deformation of the silicon wafer. Soft glue materials have better stress absorption ability. As the thickness of the glue layer increases, the stress and deformation of the silicon wafer decrease. Therefore, a soft and thick adhesive needs to be used in the chip mounting and packaging of MEMS accelerometers, and the lower the Young's modulus, the better. Ideally, the Young's modulus is zero. Summary of the Invention

[0003] In view of this, the problem to be solved by the present invention is to provide a wire bonding process in suspension and the tooling therefor.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is: a wire bonding process in suspension, including the following steps:

[0005] The first step is to fix the MEMS chip in the package through the wire bonding tooling in suspension, and wire bond the MEMS chip so that the MEMS chip is connected to the package through a metal wire.

[0006] The second step is to remove the wire bonding tooling in suspension after wire bonding is completed. The MEMS chip is connected to the package through a metal wire and there is a gap between the bottom of the MEMS chip and the package, presenting a suspended state.

[0007] The third step is to coat a protective layer on the surface where the MEMS chip is connected to the metal wire with glue having a viscosity value of 14500 cp, and then cure the protective layer under curing conditions. The coating thickness covers the solder joints at the connection between the MEMS chip and the metal wire.

[0008] In the present invention, preferably, the curing conditions in the third step are a temperature environment of 150 °C and curing for 1 hour.

[0009] In the present invention, preferably, after the third step, the package is transferred to a vacuum furnace for capping treatment, and the chamber of the package is evacuated while capping.

[0010] The suspended wire bonding tooling, adopting the above-mentioned suspended wire bonding process, includes a tooling substrate. The tooling substrate has an annular notch, and a slotted hole is symmetrically opened in the annular notch. A pressing block is accommodated in the slotted hole. The pressing block penetrates through the annular notch. Buffer mechanisms are arranged on both sides of the slotted hole. The buffer mechanisms drive the pressing block to move in the vertical direction relative to the tooling substrate, so that the pressing block abuts against the MEMS chip. The annular notch is arranged in the middle of the tooling substrate.

[0011] In the present invention, preferably, each of the buffer mechanisms includes two hollow positioning columns, an elastic member, and a connecting block. The positioning columns penetrate through the tooling substrate. One end of the elastic member is fixedly connected to the pressing block, and the other end of the elastic member is fixedly connected to the connecting block. The connecting block is fixedly connected to one end of the positioning column, and a fastening screw is threadedly installed at the other end of the positioning column.

[0012] In the present invention, preferably, the MEMS chip is built in a package. The package is provided with a square groove, and the tooling substrate abuts against the edge of the package.

[0013] In the present invention, preferably, a convex portion is fixedly provided on the side of the pressing block facing the MEMS chip. The convex portion contacts the first surface of the MEMS chip until the second surface of the MEMS chip abuts against the inner wall of the package.

[0014] In the present invention, preferably, the cross-sectional shape of the annular notch is wedge-shaped.

[0015] In the present invention, preferably, the elastic member is set as a spring or a spring piece with elastic deformation.

[0016] In the present invention, preferably, the fastening screw is provided with an external thread, and the inner edge of the positioning column is provided with an internal thread that matches the external thread.

[0017] In the present invention, preferably, round holes are opened on both sides of the slotted hole, and a shaft pin is inserted through the round holes. A positioning groove is opened on the side of the pressing block facing the MEMS chip, and the positioning groove cooperates with the shaft pin.

[0018] In the present invention, preferably, an annular connecting member is sleeved between the positioning column and the fastening screw.

[0019] The advantages and positive effects of the present invention are:

[0020] (1)First, fix the MEMS chip in the package through the suspended wire bonding tooling, and perform wire bonding on the MEMS chip so that the MEMS chip is connected to the package through metal wires. After the wire bonding is completed, remove the suspended wire bonding tooling. The MEMS chip is connected to the package through metal wires and there is a gap between the bottom of the MEMS chip and the package, showing a suspended state. The MEMS chip is lifted upward due to the surface tension of the metal wires. Apply glue with a viscosity value of 14,500 cp on the surface where the MEMS chip is connected to the metal wires to form a protective layer, and then cure the protective layer under curing conditions. The coating thickness covers the solder joints at the connection between the MEMS chip and the metal wires, thus realizing the suspended wire bonding process with zero Young's modulus, overcoming the adverse effects of external stress on the MEMS chip, and ensuring the parameter stability of the MEMS in the full-temperature environment.

[0021] (2)The suspended wire bonding tooling is provided with a buffer mechanism including an elastic member, a pressing block, and a positioning post. The mutual cooperation among the three can realize the pressing and fixing of the MEMS chip. Since the MEMS chip is small and precise in size, it also avoids the problem that the rigid pressing and fixing of the tooling may easily damage the chip due to excessive pressing on the surface of the MEMS chip. The tooling structure is simple and easy to operate, realizing the suspended wire bonding process with zero Young's modulus, and ensuring the parameter stability of the MEMS in the full-temperature environment.

[0022] (3)The suspended wire bonding tooling effectively limits the moving space of the pressing block back and forth by setting a slotted hole. Since round holes are opened on both sides of the slotted hole and a shaft pin is inserted through the round holes, a positioning groove is opened on the side of the pressing block facing the MEMS chip. The cooperation between the positioning groove and the shaft pin can limit the horizontal shaking of the pressing block, thus avoiding the problem that the pressing block is prone to shaking left and right when it returns to the initial position, and further improving the stability performance of the pressing block when pressing and fixing the MEMS chip. Description of the Drawings

[0023] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0024] Figure 1 is a schematic diagram of the steps of the suspended wire bonding process of the present invention;

[0025] Figure 2 is a perspective view of the front view of the suspended wire bonding tooling of the present invention;

[0026] Figure 3 is Figure 2 a partial enlarged schematic diagram of A in

[0027] Figure 4 is a perspective view of the back view of the suspended wire bonding tooling of the present invention;

[0028] Figure 5 is Figure 4 a partially enlarged schematic view of B in

[0029] Figure 6 is a structural cross-sectional view of the working process of the suspended wire bonding tooling of the present invention;

[0030] Figure 7 is a schematic cross-sectional view of the working process of the suspended wire bonding tooling of the present invention;

[0031] Figure 8 is a structural cross-sectional view of the suspended wire bonding tooling of the present invention coated with a protective layer.

[0032] In the figures: 1, tooling substrate; 2, annular notch; 3, straight slot; 4, pressing block; 5, buffer mechanism; 6, MEMS chip; 7, positioning post; 8, elastic member; 9, connecting block; 10, fastening screw; 11, package; 12, square slot; 13, protruding portion; 14, round hole; 15, positioning groove; 16, annular connecting member. Specific embodiments

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] It should be noted that when a component is referred to as being "fixed to" another component, it can be directly on the other component or there may also be an intermediate component. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component at the same time. When a component is considered to be "disposed on" another component, it can be directly disposed on the other component or there may be an intermediate component at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0036] As Figure 1 shown, the present invention provides a suspended wire bonding process, including the following steps:

[0037] The first step is to fix the MEMS chip 6 in the tube shell 11 by using a suspended wire bonding tool, and perform wire bonding on the MEMS chip 6 so that the MEMS chip 6 is connected to the tube shell 11 through metal wires;

[0038] In the second step, after the wire bonding is completed, the suspended wire bonding tool is removed, and the MEMS chip 6 is connected to the tube shell 11 through the metal wire, and a gap is left between the bottom of the MEMS chip 6 and the tube shell 11 to be suspended;

[0039] In the third step, glue with a viscosity of 14500cp is used to coat the surface where the MEMS chip 6 is connected to the metal wire to form a protective layer, and then the protective layer is cured when the curing conditions are met. The coating thickness covers the solder joints where the MEMS chip 6 is connected to the metal wire.

[0040] The process step of the suspended wire bonding first uses a lifting mechanism external to the suspended wire bonding tool to drive the suspended wire bonding tool to descend until the raised portion 13 of the suspended wire bonding tool contacts the upper surface of the MEMS chip 6. Since the MEMS chip 6 is small in nanometer size and has high precision requirements, the lifting mechanism moves up and down and inputs the specific value of the required lifting through the external PLC controller system, which can be suitable for high precision floating. The size of the annular notch 2 matches the edge size of the MEMS chip 6. After the MEMS chip 6 is fixed in place, it is wired so that the MEMS chip 6 passes through the metal The metal wire is connected to the tube shell 11. The metal wire can be a gold wire or a copper wire. When the gold wire is used, its radial size is 25μm, and when the copper wire is used, its radial size is 50μm, and the elongation is 0.1μm. After the wire bonding is completed, the suspended wire bonding tool is controlled by an external PLC controller to move upward and separate from the MEMS chip 6. At this time, the MEMS chip 6 is separated from the bottom of the inner wall of the tube shell 11 by the tension of the metal wire itself and is slightly lifted upward. Next, the plane where the MEMS chip 6 is connected to the metal wire is coated with glue with a viscosity of 14500cp to form a protective layer. Specifically, Figure 8 As shown, the coating thickness just covers the solder joints where the MEMS chip 6 is connected to the metal wires. The protective layer is cured under curing conditions. Specifically, the curing conditions are a temperature environment of 150°C and cured for 1 hour. After the protective layer is cured, the tube shell 11 is transferred to a vacuum furnace for capping. While performing the capping process, the chamber of the tube shell 11 is evacuated to fix the relative position relationship between the MEMS chip 6 and the tube shell 11, ensuring that the MEMS chip 6 floats within a limited range, avoiding damage to the product caused by a slight floating range of too large during the product transfer process or fractures at the metal wire solder joints. This suspended wire bonding process step can avoid the influence of external stress changes on the internal structure of the MEMS chip 6.

[0041] In this embodiment, further, the curing condition in the third step is a temperature environment of 150°C for 1 hour. The protective layer obtained under this curing condition can effectively improve the connection strength between the metal wire and the MEMS chip 6. After applying the protective glue, the average acceleration G value of the MEMS chip can reach 600 through the impact test.

[0042] In this embodiment, further, after the third step, the package 11 is transferred to a vacuum furnace for capping treatment, and the chamber of the package 11 is evacuated during capping. The purpose of the capping treatment is to ensure that the MEMS chip 6 product has good sealing performance, avoid the corrosion of certain gas components in the air on the micro-structure of the MEMS chip 6, and ensure the high reliability of the MEMS device.

[0043] According to the published patent CN113955710A, the description states that "According to the published patent CN105668507A: This patent uses bonding wires to suspend the chip in the air to avoid contact between the chip and the package housing, so as to reduce the stress change of the chip caused by the changes in the housing and the external environment. However, by analyzing its disadvantages, it is found that this solution is not feasible in reality: using bonding wires to bear the suspension of the chip, the bonding wire process is very important in terms of reliability. The welding point of each bonding wire must ensure the connection quality (high-quality requirements such as no cracking, deformation, and consistent alloy at the welding point are not allowed). External forces are not expected to touch the bonding wires and solder joints because the bonding wires are responsible for the transmission of electrical signals during the long-term use of the product. Once damaged, the resistance will increase, the electrical signal will be distorted, and the functionality of the product will be damaged. If the bonding wires also need to bear the task of chip suspension for a long time, it will inevitably affect the reliability of the solder joints and reduce the product life; the chip must be fixed on the carrier board during the bonding wire process to ensure the quality of the bonding wire solder joints. Chip suspension cannot be used for bonding wire; in order to be able to bond wire, relevant materials are placed under the chip bottom. After the bonding wire is completed, it is very difficult to remove the padding materials." It can be seen that the prior art cannot perform wire bonding during the process of keeping the chip in a suspended state, and the prior art all performs potting treatment in the inner cavity of the package 11 after wire bonding. However, after potting, the gap between the MEMS chip 6 and the package 11 is filled with a glue layer. Since the glue itself has a Young's modulus that will generate stress relative to the MEMS chip 6, this stress affects the detection of the internal structural performance indicators of the MEMS chip 6. However, the suspended wire bonding process disclosed in the present invention can reduce the stress of the MEMS chip 6. Through the impact test of the MEMS chip 6 under this process step, it can be obtained that the average acceleration G value of the MEMS chip 6 can reach 600, which has been greatly improved compared with the G value of only 12 of the MEMS chip 6 obtained by using the prior art wire bonding process steps.

[0044] The suspended wire bonding tooling adopts the above-mentioned suspended wire bonding process, asFigure 2 and Figure 3 As shown in Figure 3 , it includes a tooling substrate 1. The tooling substrate 1 has an annular notch 2. A slotted groove 3 is symmetrically provided in the annular notch 2. A pressing block 4 is accommodated in the slotted groove 3. The pressing block 4 penetrates through the annular notch 2. Buffer mechanisms 5 are provided on the sides of the slotted groove 3. The buffer mechanisms 5 drive the pressing block 4 to move in the vertical direction relative to the tooling substrate 1, so that the pressing block 4 abuts against the MEMS chip 6. By providing the slotted groove 3, the space for the pressing block 4 to move back and forth is effectively limited.

[0045] In this embodiment, further, the annular notch 2 is arranged in the middle of the tooling substrate 1. When in use, both ends of the tooling substrate 1 are synchronously pressed and gently moved downward. The annular notch 2 located in the middle of the tooling substrate 1 is more evenly stressed, improving the stability of fixing the MEMS chip 6.

[0046] As Figure 4 and Figure 5 As shown in Figure 5 , in this embodiment, further, each buffer mechanism 5 includes two hollow positioning columns 7, an elastic member 8 and a connecting block 9. The positioning columns 7 penetrate through the tooling substrate 1. One end of the elastic member 8 is fixedly connected to the pressing block 4, and the other end of the elastic member 8 is fixedly connected to the connecting block 9. The connecting block 9 is fixedly connected to one end of the positioning column 7. A fastening screw 10 is threadedly installed at the other end of the positioning column 7. The pressing block 4 moves slightly upward in the vertical direction relative to the tooling substrate 1 under the drive of the buffer mechanism 5. Specifically, when the end face of the convex portion 13 contacts the surface of the MEMS chip 6, as the tooling substrate 1 is further pressed down, since the positioning column 7 is fixedly penetrated through the tooling substrate 1, and one end of the elastic member 8 is connected to the connecting block 9 and the other end of the elastic member 8 is fixedly connected to the pressing block 4, at this time, both ends of the pressing block 4 are stressed and move upward to compress the elastic member 8. The elastic member 8 is compressed, that is, the position of the tooling substrate 1 drops relative to the pressing block 4 until it moves to the point where the annular notch 2 abuts against the edge of the package 11, realizing the fixing of the MEMS chip 6 on the package 11.

[0047] In this embodiment, further, a convex portion 13 is fixedly provided on the side of the pressing block 4 facing the MEMS chip 6. The convex portion 13 contacts the first surface of the MEMS chip 6 until the second surface of the MEMS chip 6 abuts against the inner wall of the package 11. The convex portion 13 matches the size of the MEMS chip 6 and can play a role in fixing it, solving the problem that the MEMS chip 6 is prone to shaking during the wire bonding process.

[0048] In this embodiment, further, the cross-sectional shape of the annular notch 2 is wedge-shaped. By setting the cross-sectional shape of the annular notch 2 to be wedge-shaped, it is convenient for the tooling substrate 1 to quickly align with the position of the square groove 12.

[0049] In this embodiment, further, the elastic member 8 is configured as a spring or spring sheet with elastic deformation. By arranging the mutual cooperation between the elastic member 8 and the clamping block 4 and the positioning column 7, the MEMS chip 6 can be clamped and fixed. Since the MEMS chip 6 is small and precise in size, it also avoids the problem that the rigid clamping and fixing of the tooling may over-press the surface of the MEMS chip 6 and easily damage the chip.

[0050] In this embodiment, further, the fastening screw 10 is provided with an external thread, and the inner edge of the positioning column 7 is provided with an internal thread matching the external thread. The external thread and the internal thread cooperate with each other to achieve rapid disassembly and assembly between the fastening screw and the positioning column, which is convenient for replacement of parts.

[0051] In this embodiment, further, round holes 14 are provided on both sides of the slot 3, and a shaft pin is inserted into the round hole 14. A positioning groove 15 is provided on the side of the clamping block 4 facing the MEMS chip 6, and the positioning groove 15 cooperates with the shaft pin. The positioning groove 15 cooperates with the shaft pin to limit the horizontal shaking of the clamping block 4, thereby avoiding the problem that the clamping block 4 is easy to shake left and right when returning to the initial position, and further improving the stability of the clamping block 4 when clamping and fixing the MEMS chip 6.

[0052] In this embodiment, an annular connector 16 is further provided between the positioning column 7 and the fastening screw 10. The provision of the annular connector 16 can stabilize the ends of the two positioning columns 7 in the same buffer mechanism 5, thus solving the problem of low stability due to easy shaking.

[0053] During operation, first place the package 11 in place. The package 11 is provided with a square groove 12, and an MEMS chip 6 is placed in the middle of the square groove 12. The lifting mechanism connected to the outside of the suspended wire bonding tool drives the suspended wire bonding tool to move gently downward, and places the suspended wire bonding tool directly above the package 11, so that the annular notch 2 faces the edge of the package 11. Since the annular notch 2 of the tooling substrate 1 is symmetrically provided with a slotted hole 3, the slotted hole 3 accommodates a pressing block 4. The pressing block 4 moves slightly upward in the vertical direction relative to the tooling substrate 1 driven by the buffer mechanism 5. Specifically, the buffer mechanism 5 includes two hollow positioning columns 7, an elastic member 8 and a connecting block 9. The positioning column 7 penetrates the tooling substrate 1, the connecting block 9 is fixedly connected to one end of the positioning column 7, and a fastening screw 10 is threadedly installed at the other end of the positioning column 7. After the end face of the protrusion 13 abuts against the surface of the MEMS chip 6, as the tooling substrate 1 continues to press down, since the positioning column 7 is fixedly penetrated through the tooling substrate 1, and one end of the elastic member 8 is connected to the connecting block 9, and the other end of the elastic member 8 is fixedly connected to the pressing block 4. At this time, both ends of the pressing block 4 are forced to move upward to compress the elastic member 8, and the elastic member 8 is compressed, that is, the tooling substrate 1 descends relative to the position of the pressing block 4 until it moves to the annular notch 2 abuts against the edge of the package 11, realizing the fixing of the MEMS chip 6 on the package 11. Next, the wire bonding process is performed on the MEMS chip 6. After the wire bonding is completed, the suspended wire bonding tool is lifted and removed. As the tooling substrate 1 moves upward, the elastic member 8 slowly elongates and returns to the initial state of natural elongation. The elastic member 8 drives the pressing block 4 to move downward. By providing the slotted hole 3, the space for the pressing block 4 to move back and forth is effectively limited. Since round holes 14 are provided on both sides of the slotted hole 3, a shaft pin is inserted through the round holes 14. A positioning groove 15 is provided on the side of the pressing block 4 facing the MEMS chip 6. The cooperation between the positioning groove 15 and the shaft pin can limit the horizontal shaking of the pressing block 4, thus avoiding the problem that the pressing block 4 is prone to left and right shaking when returning to the initial position, and further improving the stability performance of the pressing block 4 when pressing and fixing the MEMS chip 6, such as Figure 6 and Figure 7As shown, at this time, the MEMS chip 6 is connected to the package 11 through metal wires. Due to the surface tension of the metal wires, the MEMS chip 6 is lifted upward. At this time, a gap is generated between the MEMS chip 6 and the inner wall of the bottom of the package 11, presenting a suspended state. Next, the surface where the MEMS chip 6 is connected to the metal wires is filled with glue for potting, realizing a wire bonding process with zero Young's modulus in the suspended state, overcoming the adverse effects of external stress on the MEMS chip 6, and ensuring the parameter stability of the MEMS in the full-temperature environment. The wire bonding tooling for the suspended state is externally connected to a lifting mechanism, and the lifting mechanism is externally connected to a PLC controller or other controllers with similar functions. The controller sets fixed parameters for lifting to meet the requirements of the small size and high processing accuracy of the MEMS chip. The lifting mechanism is connected to the wire bonding tooling for the suspended state through the mounting holes on both sides of the wire bonding tooling for the suspended state. The synchronous lifting of both ends of the wire bonding tooling for the suspended state can effectively ensure the stability of the wire bonding tooling for the suspended state during rising or falling, avoiding the situation of left and right swaying.

[0054] Since the other end of the positioning post 7 is threadedly connected to the fastening screw 10, and an annular connecting piece 16 is sleeved between the positioning post 7 and the fastening screw 10, this structural design makes the ends of the two positioning posts 7 in the same set of buffer mechanisms 5 stable, solving the problem of easy shaking and low stability. In addition, when the fastening screw 10 needs to be replaced, it can be easily removed from the positioning post 7 only by reversely screwing the fastening screw 10, facilitating the timely replacement and maintenance of the fastening screw 10 and the annular connecting piece 16. The package is set as a ceramic package. Ceramic has high insulation performance and excellent high-frequency characteristics. Its linear expansion coefficient is very close to that of electronic components, with stable chemical properties and high thermal conductivity.

[0055] Due to the thermal mismatch between the materials used in the MEMS device, the temperature change required during the chip mounting and curing process will cause unwanted stress and deformation in the micro-mechanical structure. Stress and deformation have an adverse impact on the performance of the packaged components. The properties of the glue are comprehensively affected by curing conditions, glue dispensing amount, and hardness factors. In this embodiment, the glue is coated on the surface of the MEMS chip, and the coating thickness just covers the solder joints where the MEMS chip is connected to the metal wires. The metal wires can be gold wires or copper wires. For a traditional MEMS chip without protective glue coating, its average acceleration G value is 12. After coating with the protective glue, the average acceleration G value of the MEMS chip can reach 600. The protective glue is selected as an insulating silicone rubber with a hardness value of 14500 PA·s, and the curing conditions are 150 °C and a curing time of 1 hour. The protective layer obtained under these curing conditions can effectively improve the connection strength between the metal wires and the MEMS chip 6.

[0056] After the protective glue coating step of the MEMS chip is completed, the MEMS is processed in a capping step. The capping step is carried out in a vacuum furnace. During the capping process, the inner cavity of the package is evacuated, and there is a gap in the structure where the cap contacts the package.

[0057] The above has described the embodiments of the present invention in detail, but the content described is only the preferred embodiments of the present invention and cannot be considered as used to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope covered by this patent.

Claims

1. Suspended wire bonding process, characterized in that, It includes the following steps: In the first step, the MEMS chip (6) is fixed in the package (11) by a wire bonding tooling in suspension, and wire bonding is performed on the MEMS chip (6) so that the MEMS chip (6) is connected to the package (11) through metal wires; In the second step, after wire bonding is completed, the wire bonding tooling in suspension is removed. The MEMS chip (6) is connected to the package (11) through metal wires and there is a gap between the bottom of the MEMS chip (6) and the package (11) in a suspended state; In the third step, glue with a viscosity value of 14500 cp is used to coat the surface where the MEMS chip (6) is connected to the metal wires to form a protective layer, and then the protective layer is cured under curing conditions. The coating thickness covers the solder joints at the connection of the MEMS chip (6) and the metal wires; The curing conditions in the third step are a temperature environment of 150 °C and curing for 1 hour; The wire bonding tooling in suspension includes a tooling substrate (1). The tooling substrate (1) has an annular notch (2). The annular notch (2) is symmetrically provided with a slotted hole (3). The slotted hole (3) accommodates a pressing block (4). The pressing block (4) passes through the annular notch (2). Buffer mechanisms (5) are provided on both sides of the slotted hole (3). The buffer mechanisms (5) drive the pressing block (4) to move in the vertical direction relative to the tooling substrate (1) so that the pressing block (4) abuts against the MEMS chip (6). The annular notch (2) is arranged in the middle of the tooling substrate (1).

2. The wire bonding process in the air as claimed in claim 1, wherein After the third step, the package (11) is transferred to a vacuum furnace for capping treatment, and the chamber of the package (11) is evacuated while capping.

3. The wire bonding process in suspension according to claim 1, characterized in that, Each of the buffer mechanisms (5) includes two hollow positioning columns (7), an elastic member (8) and a connecting block (9). The positioning columns (7) penetrate the tooling substrate (1). One end of the elastic member (8) is fixedly connected to the pressing block (4). The other end of the elastic member (8) is fixedly connected to the connecting block (9). The connecting block (9) is fixedly connected to one end of the positioning column (7). A fastening screw (10) is threadedly installed at the other end of the positioning column (7).

4. The wire bonding process in suspension according to claim 1, characterized in that, The MEMS chip (6) is placed inside the package (11). The package (11) is provided with a square groove (12). The tooling substrate (1) abuts against the edge of the package (11).

5. The wire bonding process in suspension according to claim 4, characterized in that, A convex portion (13) is fixedly provided on the side of the pressing block (4) facing the MEMS chip (6). The convex portion (13) contacts the first surface of the MEMS chip (6) until the second surface of the MEMS chip (6) abuts against the inner wall of the package (11).

6. The wire bonding process in suspension according to claim 3, wherein, The fastening screw (10) is provided with an external thread, and the inner edge of the positioning column (7) is provided with an internal thread that matches the external thread.

7. The wire bonding process in suspension according to claim 1, wherein, Round holes (14) are provided on both sides of the slotted hole (3). A shaft pin is inserted through the round holes (14). A positioning groove (15) is provided on the side of the pressing block (4) facing the MEMS chip (6). The positioning groove (15) cooperates with the shaft pin.

8. The wire bonding process in suspension according to claim 3 or 6, characterized in that, An annular connecting member (16) is sleeved between the positioning post (7) and the fastening screw (10).

Images