Wire bonding equipment and wire bonding method

Abstract

The present invention provides a wire bonding device and a wire bonding method. The wire bonding device includes a capillary, a wire clamp, a first driving device, and a wire bonding pad; the capillary has a hollow structure and has a wire inlet and a wire outlet, the wire enters the capillary through the wire inlet and extends through the wire outlet to be connected to the device to be encapsulated; the wire clamp is adjacent to the wire inlet and is used for clamping one end of the wire adjacent to the wire inlet; the first driving device is connected to the capillary and is used for driving the capillary to move; the wire bonding pad is located on one side of the capillary and is used for carrying the wire when the capillary moves to a preset position. The wire bonding device of the present invention can, through an optimized structural design, set the second solder joint in the wire bonding process in an area outside the chip, thereby effectively avoiding surface contamination of the chip and mutual contact between the solder joints, and reducing the curvature of the wire bonding, which is beneficial to the subsequent straightening of the wire bonding. The wire bonding method of the present invention is beneficial to forming a vertical wire bond.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor chip packaging, and particularly relates to a wire bonding device and a wire bonding method. Background Art

[0002] Wire bonding is one of the key processes in the semiconductor chip packaging process. It enables the chip to complete electrical connections with the packaging substrate or lead frame, etc., so that the chip can achieve the function of transmitting electronic signals. The existing wire bonding process is as Figure 1 and Figure 2 shown. The wire 11 is threaded through the capillary 12, led from one end of the capillary 12 to the surface of the chip 13, and a first solder joint 14 (1 st bond, that is, a bond ball) is formed on the surface of the chip 13. Then, the capillary 12 is lifted to stretch the wire 11 to a predetermined arc and then led to the surface of the chip 13 again to form a second solder joint 15 (2 nd bond, that is, a wedge). After that, the wire 11 is cut, and the wire 11 is pulled up from the end of the second solder joint 15 to be pulled into the required shape and connected to an external electrical connection structure. This traditional wire bonding process has many problems. For example, due to the limitation of the structure of the existing wire bonding device, the second solder joint 15 needs to be formed on the surface of the chip 13 or the lead frame. Therefore, a position for the second solder joint 15 needs to be reserved on the chip 13 or the lead frame, which affects the further miniaturization of the device; an imprint (usually crescent-shaped due to the force applied during the wire ball cutting process) is inevitably left at the second solder joint 15 after the wire 11 is pulled up from the second solder joint 15, resulting in surface contamination of the device; in addition, as the size of the chip 13 continues to be miniaturized, the distance between the first solder joint 14 and the second solder joint 15 is continuously compressed, which not only easily leads to contact between the solder joints, but also makes it difficult to completely straighten the wire later due to the increased bending degree of the wire. With the continuous reduction of the critical dimensions of the chip and the continuous increase of the device packaging density, especially the increasing demand for vertical wire bonding in stacked packaging, the problems caused by the deficiencies of the existing wire bonding device and wire bonding method are becoming more and more prominent, and it is urgent to propose solutions. Summary of the Invention

[0003] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a wire bonding device to solve the problems in the prior art that due to the limitation of the wire bonding device, the second solder joint needs to be formed on the chip surface, which easily leads to surface contamination of the chip and contact between the solder joints, and it is difficult to completely straighten the wire later due to the increased bending degree of the wire.

[0004] To achieve the above purpose and other related purposes, the present invention provides a wire bonding device, which includes:

[0005] A bonding tool, the bonding tool having a hollow structure and having an inlet and an outlet; a bonding wire enters the bonding tool through the inlet and extends through the outlet to be connected to a device to be encapsulated;

[0006] A bonding wire clamp, adjacent to the inlet, for clamping one end of the bonding wire adjacent to the inlet;

[0007] A first driving device, connected to the bonding tool, for driving the bonding tool to move;

[0008] A bonding wire pad, located on one side of the bonding tool, for carrying the bonding wire when the bonding tool moves to a preset position.

[0009] Optionally, the wire bonding equipment further includes a sparking rod, located on one side of the bonding tool, the sparking rod being used to sinter the bonding wire into a ball.

[0010] Optionally, the wire bonding equipment further includes a first gas supply device, the first gas supply device including a first gas supply pipeline and a first gas nozzle, one end of the first gas supply pipeline being connected to a gas source and the other end being connected to the first gas nozzle; the gas ejected from the first gas nozzle faces the outlet of the bonding tool.

[0011] Optionally, there are a plurality of the first gas supply devices, and the gases supplied by the plurality of first gas supply devices face the outlet of the bonding tool from different directions.

[0012] Optionally, the wire bonding equipment further includes a second driving device, connected to the bonding wire pad, for driving the bonding wire pad to move.

[0013] Optionally, the surface of the bonding wire pad has a groove, and the groove is used to carry the bonding wire.

[0014] Optionally, the wire bonding equipment further includes a second gas supply device, the second gas supply device including a second gas supply pipeline and a second gas nozzle, one end of the second gas supply pipeline being connected to a gas source and the other end being connected to the second gas nozzle, and the gas ejected from the second gas nozzle faces the groove, so as to protect the bonding wire located in the groove from being contaminated.

[0015] The present invention also provides a wire bonding method, including the steps of:

[0016] Providing the wire bonding equipment as described in any of the foregoing solutions, and placing the device to be encapsulated below the bonding tool;

[0017] Putting the bonding wire into the inlet of the bonding tool, and then pulling the bonding wire from the outlet of the bonding tool to the surface of the device to be encapsulated and stretching it to the required arc;

[0018] Place the bonding wire adjacent to the outgoing wire port and away from the device to be encapsulated onto the bonding wire pad;

[0019] Cut the bonding wire.

[0020] Optionally, the process of cutting the bonding wire includes:

[0021] After placing the bonding wire adjacent to the outgoing wire port and away from the device to be encapsulated onto the bonding wire pad, apply pressure to form a cut at the joint of the bonding wire and the bonding wire pad;

[0022] Lift the bonding tool upward to completely cut the bonding wire.

[0023] Optionally, the bonding wire method further includes the step of straightening the bonding wire connected to the device to be encapsulated after cutting the bonding wire.

[0024] As described above, the bonding wire device of the present invention can, through an optimized structural design, set the second solder joint in the bonding wire process in an area outside the chip, thereby effectively avoiding surface contamination of the chip and mutual contact between solder joints, as well as reducing the bending degree of the bonding wire, which is beneficial to the subsequent straightening of the bonding wire. The bonding wire device of the present invention has a simple structure and is easy to use, and is particularly suitable for encapsulating devices with a high vertical degree of bonding wire, such as especially suitable for stacked packaging. Adopting the bonding wire method of the present invention is beneficial to forming vertical bonding wires, helps reduce contact short circuits between bonding wires, and thus helps improve the production yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 and Figure 2 shows a schematic diagram of a bonding wire process in the prior art.

[0026] Figure 3 shows a schematic structural diagram of the bonding wire device of the present invention.

[0027] Figure 4 shows a top view structural diagram of the bonding wire pad in the bonding wire device of the present invention.

[0028] Figure 5 shows a flowchart of the bonding wire method of the present invention.

[0029] Figure 6 and Figure 7 shows a schematic diagram of the implementation process of the bonding wire method of the present invention.

[0030] DESCRIPTION OF COMPONENT NUMERALS

[0031] 11 Bonding wire

[0032] 12 Bonding tool

[0033] 13 Chip

[0034] 14 First solder joint

[0035] 15 Second solder joint

[0036] 21 Bonding tool

[0037] 22 Bonding wire

[0038] 221 Bonding wire source

[0039] 23 Device to be encapsulated

[0040] 24 Bonding wire clamp

[0041] 25 First driving device

[0042] 26 Bonding pad

[0043] 261 Bonding pad body

[0044] 262 Groove

[0045] 263 Channel

[0046] 27 Ignition rod

[0047] 28 First gas supply device

[0048] 281 First gas supply pipeline

[0049] 282 First gas nozzle

[0050] 29 Second driving device

[0051] 30 Carrier stage

[0052] 31 Control device

[0053] 32 Gas source Detailed implementation manners

[0054] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0055] Please refer to Figures 3 to 7It should be noted that the illustrations provided in this embodiment only schematically illustrate the basic concept of the present invention. Although only the components related to the present invention are shown in the illustrations, rather than being drawn according to the number, shape, and size of the components in actual implementation, the form, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the layout form of its components may also be more complex. And to make the illustrations as concise as possible, the same structures in the same illustration are not marked repeatedly in this specification.

[0056] Embodiment 1

[0057] As Figure 3 and Figure 4 shown, the present invention provides a wire bonding device. The wire bonding device includes a capillary 21, a wire clamp 24, a first driving device 25, and a wire bonding pad 26; the capillary 21 has a hollow structure and has an inlet and an outlet. The wire 22 enters the capillary 21 through the inlet and extends through the outlet to be connected to the device to be encapsulated 23; the wire clamp 24 is adjacent to the inlet and is used to clamp one end of the wire 22 adjacent to the inlet; the first driving device 25 is connected to the capillary 21 and is used to drive the capillary 21 to move; the wire bonding pad 26 is located on one side of the capillary 21 and is used to carry the wire 22 when the capillary 21 moves to a preset position. Through the optimized structural design, the wire bonding device of the present invention can set the second solder joint in the wire bonding process in an area outside the device to be encapsulated, thereby effectively avoiding surface contamination of the device to be encapsulated and mutual contact between solder joints, and reducing the bending degree of the wire, which is beneficial to the subsequent straightening of the wire.

[0058] As an example, the wire bonding device further includes a spark rod 27, which is located on one side of the capillary 21. The wire 22 is sintered into a ball by electric spark discharge through the spark rod 27. The spark rod 27 can be connected to a driving device (not labeled) to move the spark rod 27 to a predetermined position to perform high-temperature ball burning on the wire 22 when needed.

[0059] The capillary 21 is preferably a ceramic capillary, which has an annular side wall that is connected end to end and the annular side wall has a certain height to protect the wire 22 from external contamination and keep the wire 22 as straight as possible inside the capillary 21. The outlet of the capillary 21 is usually conical, which can not only reduce the contamination caused by external air entering the capillary 21, but also facilitate applying pressure to the wire during the subsequent wire bonding operation to facilitate cutting.

[0060] As an example, the first driving device 25 includes a horizontal driving module (such as a rodless cylinder and a horizontal motor, etc.) and a vertical driving module (such as a liftable cylinder and a vertical motor, etc.) or a device that can move horizontally and vertically simultaneously, to drive the capillary 21 to move in the horizontal direction and / or the vertical direction, whereby the bonding wire 22 can be stretched into a desired shape and position (including the required length, height, curvature, etc.).

[0061] The bonding wire 22 is usually stretched from the bonding wire source 221 into the capillary 21, and the bonding wire source 221 usually includes a bobbin and the bonding wire 22 wound around the bobbin. The bonding wire 22 is stretched to the required length by continuously unwinding the bobbin. The bonding wire 22 can be a gold wire, a copper wire, an aluminum wire or other metal wires.

[0062] As an example, the bonding wire device further includes a first gas supply device 28. The first gas supply device 28 includes a first gas supply pipeline 281 and a first gas nozzle 282. One end of the first gas supply pipeline 281 is connected to the gas source 32, and the other end is connected to the first gas nozzle 282; the gas ejected from the first gas nozzle 282 faces the wire outlet of the capillary 21.

[0063] In a further example, there are multiple first gas supply devices 28, and the gases supplied by the multiple first gas supply devices 28 face the wire outlet of the capillary 21 from different directions. The gas source 32 includes but is not limited to nitrogen, helium or other inert gases; the multiple first gas supply devices 28 can be connected to the same or different gas sources 32. The first gas supply device 28 can also be provided with a driving device to move or change the spraying direction as needed to provide all-round protection for the bonding wire 22 to prevent the bonding wire 22 from being oxidized and contaminated. For example, a steering device connected to the first gas nozzle 282 can be provided, so that the gas ejected from the first gas nozzle 282 initially faces the wire outlet of the capillary 21. As the bonding wire 22 is stretched to the surface of the device to be encapsulated 23, the gas ejected from the first gas nozzle 282 synchronously turns to face the joint of the bonding wire 22 and the device to be encapsulated 23. Of course, in other examples, an independent gas supply device can also be provided to spray a protective gas onto the surface of the device to be encapsulated 23, which is not strictly limited in this embodiment.

[0064] The position of the wire bonding pad 26 may be specified, such as fixed at a preset position, usually higher than the horizontal plane where the device 23 to be encapsulated is located. However, the wire bonding pad 26 is more preferably movable to adjust the distance between the wire bonding pad 26 and the device 23 to be encapsulated according to different encapsulation requirements. Thus, as a further example, the wire bonding device further includes a second driving device 29 connected to the wire bonding pad 26 for driving the wire bonding pad 26 to move. The structure of the second driving device 29 may be the same as that of the first driving device 25.

[0065] The wire bonding pad 26 may be any structure having a bearing surface, such as a rectangular pad, a circular pad or any other shape. Its material is preferably a hard material with a smooth surface, impact resistance and not easily oxidized or contaminated, such as stainless steel, tempered glass, tempered ceramic, etc.

[0066] As Figure 4 As shown, the wire bonding pad 26 includes a rectangular wire bonding pad body 261 with grooves 262 on its surface. The grooves 262 are used to carry the wire 22 to prevent the wire 22 from moving within the wire bonding pad 26 or even falling off the wire bonding pad 26. The grooves 262 are preferably hemispherical. The upper opening size is preferably slightly larger than the wire outlet size of the bonding tool 21, such as 1.2 - 3 times the wire outlet size of the bonding tool 21, preferably 1.5 - 2 times, and the depth is preferably between 0.1 - 1 cm. Because the inventors have repeatedly verified that within this range, the bonding tool 21 can be easily placed into the grooves 262 without worrying about alignment problems, and it is not easy to slide out of the grooves 262. The grooves 262 may be one or more. Multiple grooves 262 are evenly spaced on the wire bonding pad body 261 to carry multiple wires 22 simultaneously, and the bonding tool 21 may also be multiple. Thus, synchronous encapsulation of multiple wires 22 can be achieved, which is not only beneficial to improving production efficiency, but also better control the pitch and height of the wires during the synchronous process (for example, in stacked encapsulation, it is usually required that the pitch and height of multiple wires between two packages are uniform), which is beneficial to improving the encapsulation yield.

[0067] As an example, the wire bonding device further includes a second gas supply device (not shown). The second gas supply device includes a second gas supply pipeline and a second gas nozzle. One end of the second gas supply pipeline is connected to the gas source 32, and the other end is connected to the second gas nozzle. The gas ejected from the second gas nozzle is directed towards the grooves 262 to protect the wire 22 located in the grooves 262 from being contaminated.

[0068] In a further example, a channel 263 connected to the groove 262 may also be provided on the bonding wire pad body 261, and the gas supplied by the second gas supply device can be stably supplied into the groove 262 along the channel 263 to prevent the gas from blowing up the bonding wire 22; alternatively, the second gas supply pipeline and the second gas nozzle may be disposed in the channel 263 to facilitate the fixation of the second gas supply pipeline and the second gas nozzle and reduce the possibility of collision between the second gas supply pipeline and the second gas nozzle and other devices.

[0069] As an example, the wire bonding device further includes a stage 30, located below the capillary 21, for carrying the device to be encapsulated 23. The stage 30 can be connected to a driving device to adjust its position as needed, thereby adjusting the distance between the device to be encapsulated 23 and the capillary 21.

[0070] The wire bonding device further includes a bonding device (not shown), such as an ultrasonic bonding device (ultrasonic generating device) or a thermal bonding device (heating device), etc., and the bonding device is connected to the capillary 21 to bond the bonding wire 22 and the device to be encapsulated 23.

[0071] As an example, the wire bonding device further includes a control device 31, such as a computer, and the control device 31 is at least connected to the first driving device 25 and the second driving device 29 to move the capillary 21 and the bonding wire pad 26 according to a preset process flow to complete the required wire bonding and encapsulation process.

[0072] The main difference between performing wire bonding operations using the wire bonding device of the present invention and using a conventional wire bonding device is that during the wire bonding operation using a conventional wire bonding device, the second solder joint needs to be formed on the surface of the chip or the lead frame; while when performing wire bonding operations using the wire bonding device of the present invention, the second solder joint is formed on the bonding wire pad 26. Next, in combination with Figures 5 to 7 further explanation will be given.

[0073] As Figure 5 shown, the present invention also provides a wire bonding method, including the steps of:

[0074] S01: Provide the wire bonding device as described in any of the foregoing solutions, and place the device to be encapsulated 23 below the capillary 21;

[0075] S02: Place the bonding wire 22 into the inlet of the capillary 21, and then draw the bonding wire 22 from the outlet of the capillary 21 to the surface of the device to be encapsulated 23 and stretch it to the required arc;

[0076] S03: Place the bonding wire 22 adjacent to the outlet and away from the device 23 to be encapsulated onto the bonding pad 26;

[0077] S04: Cut the bonding wire 22.

[0078] For the specific operations of the bonding wire method, please refer to Figure 6 and Figure 7 , place the device 23 to be encapsulated on the stage 30 (if the stage 30 is not provided, it can be placed on other horizontal platforms). To ensure sufficient contact between the bonding wire 22 and the surface of the device 23 to be encapsulated, before joining one end of the bonding wire 22 to the surface of the device 23 to be encapsulated, it further includes the step of sintering the bonding wire 22 into a bonding ball at high temperature using a spark rod 27. After forming the ball, the capillary 21 moves to the surface of the device 23 to be encapsulated to make the bonding ball contact the device 23 to be encapsulated, and then the capillary 21 applies a certain pressure for bonding (thermal compression bonding, ultrasonic bonding, or thermosonic bonding can be used, depending on the different bonding devices). During this process, to avoid oxidation and contamination of the bonding ball, an inert gas can be sprayed onto the bonding wire 22 before forming the ball so that the ball forming process is carried out in an inert gas atmosphere; after the bonding ball contacts the device 23 to be encapsulated, continue to spray inert gas towards the bonding position of the bonding ball and the device 23 to be encapsulated.

[0079] As an example, the process of cutting the bonding wire 22, that is, the step S04 includes:

[0080] After placing the bonding wire 22 adjacent to the outlet and away from the device 23 to be encapsulated onto the bonding pad 26, apply pressure to form a cut at the joint of the bonding wire 22 and the bonding pad 26;

[0081] Lift the capillary 21 upward to completely cut the bonding wire 22.

[0082] During this process, since the joint is on the bonding pad 26, there is no need to worry that the remaining mark will contaminate the device 23 to be encapsulated. Of course, to improve the cleanliness of the next bonding wire process, the bonding pad 26 can be cleaned after the current bonding wire process, for example, by blowing with gas, such as spraying gas using the aforementioned first gas supply device 28 for blowing.

[0083] As an example, the wire bonding method further includes a step of cutting the wire bond 22 and then straightening the wire bond 22 connected to the device to be packaged 23. Since the wire bonding device of the present invention is adopted, the second solder joint does not need to be formed on the surface of the device to be packaged 23 or the lead frame, and the bending degree of the wire bond can be greatly reduced, making the process of straightening the wire bond extremely easy. Therefore, the wire bonding method using the wire bonding device of the present invention is particularly suitable for device packaging with high requirements for the perpendicularity of the wire bond, such as stacked packaging. At the same time, in the context of the continuous reduction of the critical dimensions of the chip and the continuous increase in the packaging density of devices, the advantages of the wire bonding device and the wire bonding method of the present invention will become more and more prominent.

[0084] In summary, the present invention provides a wire bonding device and a wire bonding method. The wire bonding device includes a capillary, a wire bond clamp, a first driving device, and a wire bonding pad; the capillary is a hollow structure and has an inlet and an outlet, and the wire bond enters the capillary through the inlet and extends through the outlet to be connected to the device to be packaged; the wire bond clamp is adjacent to the inlet and is used to clamp one end of the wire bond adjacent to the inlet; the first driving device is connected to the capillary and is used to drive the capillary to move; the wire bonding pad is located on one side of the capillary and is used to carry the wire bond when the capillary moves to a preset position. Through the optimized structural design, the wire bonding device of the present invention can set the second solder joint in the area outside the chip during the wire bonding process, thereby effectively avoiding the surface contamination of the chip and the mutual contact between the solder joints, and reducing the bending degree of the wire bond, which is beneficial to the subsequent straightening of the wire bond. The wire bonding device of the present invention has a simple structure and is easy to use, and is particularly suitable for device packaging with high requirements for the perpendicularity of the wire bond, such as especially suitable for stacked packaging. Adopting the wire bonding method of the present invention is beneficial to forming perpendicular wire bonds, helps to reduce the contact short circuit between wire bonds, and thus helps to improve the production yield. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0085] The above embodiments are only illustrative of the principles and effects of the present invention, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A wire bonding device, characterized in that, Comprising: A capillary, the capillary being of a hollow structure and having an inlet and an outlet. The bonding wire enters the capillary through the inlet and extends through the outlet to be connected to the device to be encapsulated. A bonding wire clamp, adjacent to the inlet, for clamping one end of the bonding wire adjacent to the inlet. A first driving device, connected to the capillary, for driving the capillary to move. A bonding wire pad, located on one side of the capillary, for carrying the bonding wire when the capillary moves to a preset position. The surface of the bonding wire pad has a groove for carrying the bonding wire. The position of the bonding wire pad is higher than the horizontal plane where the device to be encapsulated is located.

2. The wire bonding device according to claim 1, characterized in that: The wire bonding device further includes a sparking rod, located on one side of the capillary, and the sparking rod is used to sinter the bonding wire into a ball.

3. The wire bonding device according to claim 1, characterized in that: The wire bonding device further includes a first gas supply device, the first gas supply device including a first gas supply pipeline and a first gas nozzle. One end of the first gas supply pipeline is connected to a gas source, and the other end is connected to the first gas nozzle. The gas ejected from the first gas nozzle is directed towards the outlet of the capillary.

4. The wire bonding device according to claim 3, characterized in that: There are a plurality of the first gas supply devices, and the gases supplied by the plurality of first gas supply devices are directed towards the outlet of the capillary from different directions.

5. The wire bonding device according to claim 1, characterized in that: The wire bonding device further includes a second driving device, connected to the bonding wire pad, for driving the bonding wire pad to move.

6. The wire bonding device according to claim 1, characterized in that: The wire bonding device further includes a second gas supply device, the second gas supply device including a second gas supply pipeline and a second gas nozzle. One end of the second gas supply pipeline is connected to a gas source, and the other end is connected to the second gas nozzle. The gas ejected from the second gas nozzle is directed towards the groove to protect the bonding wire located in the groove from being contaminated.

7. A wire bonding method, characterized in that, Including the steps: Providing the wire bonding device according to any one of claims 1-6, placing the device to be encapsulated below the capillary; putting the bonding wire into the inlet of the capillary, and then pulling the bonding wire from the outlet of the capillary to the surface of the device to be encapsulated and stretching it to the required curvature. Placing the bonding wire adjacent to the outlet and away from the device to be encapsulated on the bonding wire pad. Cutting the bonding wire.

8. The wire bonding method according to claim 7, characterized in that, The process of cutting the bonding wire includes: After placing the bonding wire adjacent to the outlet and away from the device to be encapsulated on the bonding wire pad, applying pressure to form a cut at the joint of the bonding wire and the bonding wire pad. Lifting the capillary upward to completely cut the bonding wire.

9. The wire bonding method according to claim 7 or 8, characterized in that: The wire bonding method further includes the step of straightening the bonding wire connected to the device to be encapsulated after cutting the bonding wire.

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