A short transducer

Abstract

The present application relates to a kind of short transducers, including amplitude transformer (1), porcelain nozzle screw (2), bonding tool (3), piezoelectric ceramic sheet (4), copper sheet (5), back cover plate (6) and flange (7), the amplitude transformer (1) includes amplitude transformer head and amplitude transformer body, the amplitude transformer head is from the top end of amplitude transformer to the front vibration node (8) of transducer first main frequency, and the amplitude transformer body is from the front vibration node (8) of transducer first main frequency to the mounting surface of piezoelectric ceramic sheet.Compared with the prior art, the present application has the advantages of good mode, anti-interference, light weight and high rigidity.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging equipment technology, and in particular to a short transducer that has good vibration modes at both the first and second main frequencies, while also being anti-interference, lightweight, and highly rigid. Background Technology

[0002] Wire bonding, the interconnection between integrated circuit chips and the bonding pad, is a core process in semiconductor chip packaging. In modern wire bonding machines, the ultrasonic transducer plays a crucial role in bonding quality. During wire bonding, the wire, under the combined influence of heat, pressure, and ultrasonic energy, undergoes interatomic diffusion with the pad metal to achieve bonding. The ultrasonic system, the core component of the bonding equipment, consists of a generator, a transducer, and a bonding tool. The generator generates the ultrasonic frequency electrical signal, the transducer converts electrical energy into mechanical energy, and the bonding tool fixes the wire, transmits pressure and ultrasonic energy, and performs wire arcing. The transducer is the most important component in the entire ultrasonic system; adjusting the transducer alters the vibration trajectory, amplitude, and system resonant frequency of the bonding tool. In reality, the vibration of the bonding tool is not a one-dimensional vibration in one direction, but a three-dimensional vibration with amplitude in all three directions. The vibration modes of the bonding tool directly determine the quality of the wire bond, especially for sensitive chips, where the vibration modes play a decisive role. Since the bonding tool is only connected to the transducer, the transducer's vibration modes directly determine the bonding tool's vibration modes. The transducer includes an amplitude transformer head, amplitude transformer body, flange structure, motor, etc., with the motor mainly composed of a front cover plate, bolts, piezoelectric ceramic plates, copper plates, and a rear cover plate. For short transducers, the motor's front cover plate is usually designed as a single unit with the amplitude transformer, making the amplitude transformer particularly important. The vibration modes of the amplitude transformer determine the transducer's vibration modes, thus determining the quality of the wire bonding.

[0003] Wire bonding is evolving towards ultra-fine bonding and large bonding areas with advancements in front-end processes, placing increasingly higher demands on transducers. The advantages of short transducers are becoming increasingly apparent, improving system stiffness, stability, bonding accuracy, and reducing the adverse effects of thermal expansion and weight. Traditional transducers are typically designed for three times the wavelength, while short transducers can reduce this to one wavelength. Short transducers have one or two operating frequencies: a primary frequency between 130kHz and 150kHz, and a secondary frequency between 70kHz and 90kHz. The primary frequency is designed for one wavelength, while the secondary frequency is designed for half a wavelength. The amplitude transformer structure of the short transducer must simultaneously accommodate the vibration modes of both the primary and secondary frequencies; therefore, the structural design of the amplitude transformer becomes both a challenge and a key focus for short transducers.

[0004] Patent ZL201420175990.8 discloses a short transducer with a flange structure. This short transducer has one or more operating frequencies, with the first dominant frequency located between 120kHz and 140kHz. This flange structure allows the short transducer to be mounted on a machine for use, but it also causes significant changes in the transducer's frequency and impedance. A major reason for this is that the machine's flange itself vibrates considerably during operation, which is transmitted to the transducer and affects its normal and stable operation.

[0005] Patent 202122609250.3 discloses a short transducer with an improved flange structure. It uses a flange structure with a downward sloping surface and two slots to achieve bidirectional transmission of ultrasonic vibration of the transducer and machine head vibration, which avoids energy loss and ensures that the frequency, impedance and working mode of the transducer are not affected by being locked to the machine, so that the transducer can work more stably.

[0006] While this structure can achieve some basic functions of a short transducer, in practical applications, it is relatively simple and lacks the structure required to optimize the vibration modes of the first and second dominant frequencies of the short transducer. Therefore, it is difficult to ensure that the first and second dominant frequencies of the short transducer have good vibration modes without structural optimization, while ensuring that there are no interfering modes nearby, maintaining the amplification factor of these two dominant frequencies, and achieving a small weight and high rigidity for the short transducer. Existing technologies cannot achieve all of these. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a short transducer that has good vibration modes at both the first and second main frequencies, and also features anti-interference, light weight and high rigidity.

[0008] The objective of this invention can be achieved through the following technical solution: A short transducer, comprising an amplitude transformer, a ceramic nozzle screw, a bonding tool, a piezoelectric ceramic plate, a copper plate, a rear cover plate, and a flange, characterized in that the amplitude transformer comprises an amplitude transformer head and an amplitude transformer body, wherein the amplitude transformer head is the front vibration node from the top of the amplitude transformer to the first main frequency of the transducer, and the amplitude transformer body is the front vibration node from the first main frequency of the transducer to the mounting surface of the piezoelectric ceramic plate.

[0009] Furthermore, the amplitude rod head structure is wider at the top and narrower at the bottom, and the width D1 at the top and the width d1 at the front vibration node satisfy the following ratio: D1:d1=(1.1~1.4):1.

[0010] Furthermore, the cross-sectional structure of the amplitude transformer head is a stepped shape that gradually shrinks from the top to the front vibration node, or a stepped shape that decreases steplessly.

[0011] Furthermore, the head of the amplitude transformer is provided with a ceramic nozzle hole, a square boss is provided above the ceramic nozzle hole, and a stress relief groove and a limiting step are provided inside the ceramic nozzle hole.

[0012] Furthermore, a circular boss may be provided below the ceramic nozzle hole.

[0013] Furthermore, the amplitude transformer body includes a front part connected to the head of the amplitude transformer, a tail part extending from the flange to the mounting surface of the piezoelectric ceramic sheet, and a middle part connecting the front part and the tail part. The front part is trapezoidal, with its upper and lower surfaces and sides all being inclined. A transition step is provided between the front part and the middle part, with a height of 0.5~2mm. The upper and lower surfaces of the middle part are planar, and the sides form an integral inclined surface with the front part.

[0014] Furthermore, the width d2 at the connection between the amplitude rod body and the amplitude rod head and the width D2 at the tail of the amplitude rod body satisfy the following proportional relationship: D2:d2=(1.5~1.9):1.

[0015] Furthermore, the connection between the amplitude rod head and the amplitude rod body is a transitional step with a height of 0.05~0.5mm.

[0016] Furthermore, the connection between the amplitude rod head and the amplitude rod body is provided with left and right side grooves.

[0017] Furthermore, the length L1 of the amplitude transformer head and the length L2 of the amplitude transformer body satisfy L1:L2=1:(1.2~1.5).

[0018] The transducer's first primary frequency is 130kHz~150kHz. The rear vibration node of the first primary frequency is located within the piezoelectric ceramic, while the positions of the front and rear vibration nodes are controlled by changing the material and dimensions of the amplitude transformer. The second primary frequency of the transducer is also achieved by optimizing the material and dimensions of the amplitude transformer. The amplitude transformer can be made of metal materials such as aluminum alloy, stainless steel, Invar alloy, and titanium alloy.

[0019] The transducer described above consists of an amplitude transformer, ceramic nozzle screws, bonding tools, a back cover plate, a piezoelectric ceramic plate, a copper plate, and bolts, which together form the desired resonant frequency. The transducer can have one or two operating frequencies.

[0020] The head of the aforementioned amplitude transformer has threaded holes and through holes on its side for ceramic nozzle screws, and threaded holes for bolts at its tail.

[0021] The above-mentioned amplitude rod has a symmetrical structure on the left and right, and can be a symmetrical or asymmetrical structure on the top and bottom.

[0022] The aforementioned amplitude transformer may have side grooves on its left and right sides at the front vibration node of the first main frequency of the transducer to further isolate interference modes.

[0023] This invention employs an improved amplitude transformer structure suitable for short transducers. The short transducer used in wire bonding machines mainly consists of an amplitude transformer, a flange structure, and a motor. The motor primarily comprises a front cover plate, bolts, a piezoelectric ceramic plate, a copper plate, and a rear cover plate. Additionally, it includes a ceramic nozzle screw and bonding tools. The piezoelectric ceramic plate generates ultrasonic vibrations, converting electrical energy into mechanical energy. A hole at the front end of the amplitude transformer is used to mount the bonding tools, and the ceramic nozzle screw secures them together. The rear cover plate fixes the piezoelectric plate, ensuring stable ultrasonic output. The amplitude transformer amplifies the ultrasonic vibration amplitude generated by the piezoelectric ceramic and transmits it to the bonding tools according to the transducer's vibration modes.

[0024] The first segment of the amplitude transformer is the head, extending from the top of the transformer to the pre-vibration node of the transducer's first principal frequency. This transition from the node position increases the amplifier's magnification. The left and right sides are wider at the top and narrower at the bottom, while the top and bottom are flat with a square boss above the ceramic nozzle hole. This structure ensures the rigidity and usability of the head without making it too heavy. The second segment is the body, extending from the pre-vibration node of the transducer's first principal frequency to the mounting surface of the piezoelectric ceramic plate. The top and bottom structures are sloped along the head direction before transitioning to a flat surface via a step, while the left and right structures are entirely sloped until they become flat at the mounting flange. A step is present at the junction of the second and first segments. Because of the abrupt change in the cross-sectional area near the vibration node, the amplifier's magnification is increased. This structure further enhances the amplifier's magnification, optimizes its vibration modes, and isolates other interfering modes.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] I. The improved amplitude transformer structure of this invention can have a relatively ideal vibration amplitude amplification factor, so that the short transducer can achieve the required bonding strength without adding a lot of power.

[0027] Second, the improved amplitude transformer structure of this invention has relatively ideal vibration modes. In addition to ensuring that the first and second main frequencies have relatively ideal transverse modes, it also ensures that there is no interference from bending and torsional modes near these two main frequencies, thereby enhancing the stability of the short transducer operation.

[0028] Third, the improved amplitude rod structure of this invention also ensures the rigidity of the short transducer itself, while minimizing the weight of the short transducer. Attached Figure Description

[0029] Figure 1This is a three-dimensional structural diagram of the short transducer with improved amplitude rod structure according to the present invention;

[0030] Figure 2 This is a schematic diagram of the planar structure and vibration amplitude variation curve of the short transducer with the improved structure of the amplitude transformer of the present invention;

[0031] Figure 3 This is the internal structure of the ceramic nozzle hole at the head of the amplitude transformer of the present invention;

[0032] Figure 4 This is a three-dimensional structural diagram of another short transducer with an improved amplitude rod structure according to the present invention;

[0033] Figure 5 This is a schematic diagram of the impedance-frequency of the short transducer with the improved structure of the amplitude transformer of the present invention at the first main frequency;

[0034] Figure 6 This is a schematic diagram of the impedance-frequency of the short transducer with the improved structure of the amplitude transformer of the present invention at the second main frequency.

[0035] The numbers in the diagram are as follows:

[0036] 1. Amplitude bar, 1a. Ceramic nozzle hole, 1b. Boss, 1c. Left and right side grooves, 1d. Circular boss, 1e. Stress relief groove, 1f. Limiting step, 2. Ceramic nozzle screw, 3. Bonding tool, 4. Piezoelectric ceramic sheet, 5. Copper sheet, 6. Rear cover plate, 7. Flange, 8. Front vibration node, 9. Rear vibration node. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0038] Example 1

[0039] like Figure 1-2 As shown, the short transducer used in the wire bonding machine of this invention mainly consists of an amplitude transformer 1, a flange 7, and a motor, as well as ceramic nozzle screws 2 and bonding tools 3. The motor mainly consists of a front cover plate, bolts, a piezoelectric ceramic plate 4, a copper sheet 5, and a rear cover plate 6. The front cover plate of the motor and the amplitude transformer 1 are integral. The piezoelectric ceramic plate 4 is responsible for generating ultrasonic vibration, realizing the conversion of electrical energy into mechanical energy.

[0040] At the front end of the amplitude transformer 1, there is a ceramic nozzle hole 1a for mounting the bonding tool 3. The ceramic nozzle screw 2 is responsible for locking the amplitude transformer 1 and the bonding tool 3 together. The rear cover plate 6 and bolts are responsible for fixing the piezoelectric ceramic plate 4 and the copper plate 5, and providing a certain preload to the piezoelectric ceramic plate 4 to achieve stable ultrasonic output. The amplitude transformer 1 is responsible for amplifying the ultrasonic vibration amplitude generated by the piezoelectric ceramic 4 and transmitting it to the bonding tool 3 according to the vibration mode of the transducer. The rigidity of the transducer is also mainly achieved by the amplitude transformer 1. The flange 7 is integrated with the amplitude transformer 1. The flange 7 has mounting holes, and the transducer is installed and fixed to the machine by screws through the flange 7.

[0041] The short transducer consists of an amplitude transformer 1, a ceramic nozzle screw 2, a bonding tool 3, a back cover plate 6, a piezoelectric ceramic plate 4, a copper plate 5, and bolts, which together form the desired resonant frequency. It can have one or two operating frequencies. This invention employs an improved amplitude transformer structure. The first segment of the amplitude transformer 1 is the amplitude transformer head: from the top of the amplitude transformer 1 to the front vibration node 8 of the first main frequency of the transducer. This turning point from the node position can increase the amplification factor of the amplitude transformer. The amplitude transformer head structure: the left and right structure is wide at the top and narrows at the bottom (the width D1 at the top and the width d1 at the front vibration node 8 satisfy the following ratio: D1:d1=1.1~1.4:1, which can be a stepped shape with gradual shrinkage or a stepless decreasing shape. In this embodiment, it is a stepped shape with gradual shrinkage, D1:d1=1.3:1). The upper and lower structure is planar and the amplitude transformer head is provided with a ceramic nozzle hole 1a. Above the ceramic nozzle hole 1a is a square boss 1b. This structure ensures the rigidity and usability of the amplitude transformer head without making the amplitude transformer head too heavy. The ceramic nozzle hole 1a is provided with a stress relief groove 1e to reduce the locking stress of the ceramic nozzle and a limiting step 1f to limit the installation height of the ceramic nozzle. See [reference needed] Figure 3 .

[0042] The second section of the amplitude transformer 1 is the amplitude transformer body: from the front vibration node 8 of the transducer's first main frequency to the mounting surface of the piezoelectric ceramic plate 4, the upper and lower structures of the amplitude transformer body are inclined surfaces along the head direction, then transition to a flat surface via steps; the left and right structures are fully inclined surfaces until they become flat surfaces at the mounting flange 7. Specifically, the amplitude transformer body includes a front part, a middle part, and a tail part. The front part connects to the head of the amplitude transformer, the middle part connects the front part and the tail part, and the tail part extends from the flange 7 to the mounting surface of the piezoelectric ceramic plate. The front part is trapezoidal, with both its upper and lower surfaces inclined. A transition step is provided between the front and middle parts, with a height of 0.5~2mm (0.8mm in this embodiment). The upper and lower surfaces of the middle part are flat, and the sides form an integral inclined surface with the front part. The width d2 at the connection between the luffing rod body and the luffing rod head and the width D2 at the tail of the luffing rod body satisfy the following ratio: D2:d2=1.5~1.9:1 (in this embodiment, D2:d2=1.7:1). The connection between the luffing rod head and the luffing rod body is a transition step, and the height of the transition step is 0.05~0.5mm (0.1mm in this embodiment).

[0043] Side grooves 1c can be provided on the left and right sides of the amplitude transformer 1 near the pre-vibration node 8 of the first main frequency of the transducer. The amplitude transformer 1 has a symmetrical structure on both sides and on both sides. This structure further increases the amplification factor of the amplitude transformer 1, while optimizing the vibration mode of the amplitude transformer 1 and isolating other interfering modes.

[0044] Figure 5 and Figure 6 The impedance-frequency diagrams of the short transducer with the improved amplitude transformer structure in this embodiment are shown for the first primary frequency (130kHz~150kHz) and the second primary frequency (70kHz~90kHz). The diagrams show that, apart from the excellent operating modes at the first and second primary frequencies, there are no interfering modes nearby. This improved structure ensures the bonding effect of the short transducer and enhances its operational stability.

[0045] Example 2

[0046] In this embodiment, the short transducer is as follows: Figure 3 As shown, this is an asymmetric structure.

[0047] The ceramic nozzle hole 1a has a square protrusion 1b above it and a circular protrusion 1d below it. The width D1 at the top of the amplitude rod head and the width d1 at the front vibration node 8 satisfy the following ratio: D1:d1=1.2:1;

[0048] The width d2 at the connection between the luffing boom body and the head of the luffing boom and the width D2 at the tail of the luffing boom body satisfy the following ratio: D2:d2=1.6:1. The rest is the same as in Example 1.

[0049] Example 3

[0050] The width D1 at the top of the amplitude transformer head and the width d1 at the front vibration node 8 satisfy the following proportional relationship: D1:d1=1.4:1;

[0051] The width d2 at the connection between the luffing boom body and the head of the luffing boom and the width D2 at the tail of the luffing boom body satisfy the following ratio: D2:d2=1.9:1. The rest is the same as in Example 1.

Claims

1. A short transducer, comprising an amplitude transformer (1), a ceramic nozzle screw (2), a bonding tool (3), a piezoelectric ceramic plate (4), a copper plate (5), a rear cover plate (6), and a flange (7), characterized in that, The amplitude rod (1) includes an amplitude rod head and an amplitude rod body. The amplitude rod head is the front vibration node (8) from the top of the amplitude rod to the first main frequency of the transducer, and the amplitude rod body is the mounting surface of the piezoelectric ceramic sheet from the front vibration node (8) of the first main frequency of the transducer. The amplitude rod head structure is wide at the top and narrows at the bottom. The width D1 at the top and the width d1 at the front vibration node (8) satisfy the following ratio: D1:d1=(1.1~1.4):1; The cross-sectional structure of the amplitude rod head is a stepped structure that gradually narrows from the top to the front vibration node (8), or a trapezoidal shape. The amplitude transformer body includes a front part connected to the head of the amplitude transformer, a tail part extending from the flange (7) to the mounting surface of the piezoelectric ceramic sheet (4), and a middle part connecting the front part and the tail part. The front part is trapezoidal, with its upper and lower surfaces and sides all being inclined. A transition step is provided between the front part and the middle part, with a height of 0.5~2.0mm. The upper and lower surfaces of the middle part are planar, and the sides form an integral inclined surface with the front part.

2. A short transducer according to claim 1, characterized in that, The head of the amplitude transformer is provided with a ceramic nozzle hole (1a), and a square boss (1b) is provided above the ceramic nozzle hole (1a). The ceramic nozzle hole (1a) is provided with a stress relief groove and a limiting step.

3. A short transducer according to claim 2, characterized in that, A circular protrusion is provided below the porcelain nozzle hole (1a).

4. A short transducer according to claim 1, characterized in that, The width d2 at the connection between the luffing rod body and the head of the luffing rod and the width D2 at the tail of the luffing rod body satisfy the following proportional relationship: D2:d2=(1.5~1.9):

1.

5. A short transducer according to claim 1, characterized in that, The connection between the amplitude rod head and the amplitude rod body is a transition step with a height of 0.05~0.5mm.

6. A short transducer according to claim 1, characterized in that, The connection between the head of the luffing rod and the body of the luffing rod is provided with left and right side grooves (1c).

7. A short transducer according to claim 1, characterized in that, The length L1 of the amplitude transformer head and the length L2 of the amplitude transformer body satisfy L1:L2=1:(1.2~1.5). The first main frequency of the transducer is 130kHz~150kHz. The rear vibration node (9) of the first main frequency of the transducer is located inside the piezoelectric ceramic. The positions of the front vibration node (8) and the rear vibration node (9) are controlled by the material and size of the amplitude transformer.

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