JPS63242479A - Ultrasonic welding method using coupling oscillation and its equipment - Google Patents

Abstract

PURPOSE:To perform the joining with a high degree of safety by allowing a welding chip part to carry out the coupling oscillation and controlling the oscillation amplitude and oscillation phase of each oscillation component to control a shape of an oscillation locus of a welding chip. CONSTITUTION:A bending oscillating rod 21 with the different oscillation degree according to the oscillating direction is used and driven by plural vertical oscillating system and bending oscillating system or torsional oscillating system 22 and 23 arranged at right angles or at prescribed angles. The driving position of the composite bending oscillating rod 21 in the case of being driven by the vertical oscillating system and the bending oscillating system is a node part of the bending oscillation in the different oscillating direction and the oscillating rod 21 is driven at the positions 21b and 21c close to a loop part of the oscillation in the driving direction and moreover, driven at the node part in the different oscillating and driving oscillating direction with the bending oscillating system, by which the stable coupling oscillation is obtained. As to the welding method, samples 24 and 25 to be welded are overlapped each other and impressed with the static pressure 20 by the welding chip 21a part and the oscillation amplitude and oscillation phase of the plural oscillating systems are controlled to control the oscillation locus of the welding chip and the joining is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ultrasonic welding method and apparatus for joining similar and dissimilar materials using a welding tip that generates complex vibrations. Ultrasonic welding can locally join similar or dissimilar metal materials, ceramics, polymer materials, etc. in a solid state, and can be used to join parts of various shapes, electronic parts, and various minute parts. In particular, it is used in so-called ultrasonic wire bonding, which uses fine conductive wires such as aluminum or copper to connect the fine electrical terminals of semiconductor chips such as integrated circuits and transistors to the external terminals. Widely used in electronic components,
As the miniaturization of optical circuit components progresses, more stable bonding of minute parts is required, and as the degree of integration increases and the number of terminals extracted from one semiconductor chip increases, extremely high welding stability and reliability are required. be done.

(Prior art) Conventional ultrasonic welding equipment uses a single imaging system, and the welding method involves overlapping welding samples and applying static pressure to the welding part with the welding tip. Depending on the type of specimen, joining is performed by vibrating parallel or perpendicular to the welding surface, and in some cases local heating is also used. Furthermore, the vibration direction of the welding tip is, of course, single, making welding difficult depending on the orientation of the welding sample, and also having the disadvantage that the welding condition is not uniform. For example, in ultrasonic wire bonding, bond strength is obtained only when the vibration direction of the welding tip and the length direction of the thin wire of the bonded sample are the same, and the stability and reliability of the bond are not always sufficient. .

(Problems to be Solved by the Invention) The present invention uses a single ultrasonic vibration system to eliminate dust, welding tip vibration, and ultrasonic vibration, which does not necessarily provide sufficient bonding stability. The stability of various welding methods such as micro bonding, ultrasonic wire bonding, etc. can be improved by configuring a welding tip that generates two-dimensional or three-dimensional complex vibrations with different vibration directions and performing various types of control. The purpose is to improve this by realizing a uniform bonding state over the entire area, and to eliminate or reduce changes in bonding strength due to the direction of vibration of the welding tip.

(Means for Solving the Problems) The present invention uses a conventional single ultrasonic vibration system and uses a single vibration of the welding tip. In order to improve the stability of wire bonding joints by using compound vibrations and to eliminate or reduce changes in bond strength due to vibration directions of the welding tips, welding tip Ia is configured to make compound perturbations in different vibration directions. Then, by controlling the magnitude (imaging amplitude) and vibration phase of the components of vibrations 1d and 1c with different vibration directions, the vibration locus of the welding tip la can be adjusted in two or three dimensions.
By controlling dimensionally and controlling and driving by temporally changing the vibration locus and driving period, a more uniform joining condition is achieved, resulting in highly stable welding and welding without directionality. This is what I am trying to do.

Furthermore, by controlling the vibration component by applying vibration perpendicular to the welding surface to the static pressure of the weld, which was conventionally held constant during the welding period, it is possible to equivalently optimally control the static pressure of the weld. The aim is to achieve even more stable bonding.

(Function) When compound vibrations with different vibration frequencies are used, the vibration locus of the welding tip becomes random in each direction, and the directionality of minute parts of the joint becomes different from the case of vibration in only one direction. This eliminates the problem of welding, making it possible to more uniformly join the entire welded part to obtain a complete joint, and also increasing the joint strength.

When compound vibrations with the same vibration frequency are used, by controlling the vibration amplitude and vibration phase of each vibration 1d and le, it is possible to control the vibration direction of the welding tip portion 1a, and also to control the vibration trajectory. It is also possible to control the

Further, by applying vibration components of different vibration frequencies to the complex vibration of the same frequency, it is also possible to add random vibration locus components to the vibration vector whose main vibration direction is controlled.

In addition, if compound vibration causes slippage between the welding tip or the welding sample at the beginning of welding, making it difficult to drive, or if it is difficult to achieve a stable joint, some vibrations may be applied first to reduce the After welding, stable welding can be achieved by applying the other vibration after a period of time and increasing the joint area by compound vibration. It is also clear that stable welding can be achieved by continuously controlling the envelope waveform of each vibration component.

In addition, the static pressure applied to the weld has a large effect on the welding condition, and there is an optimal static pressure depending on the progress stage of the weld, but when joining by ultrasonic welding, the welding time is extremely short and cannot be controlled. Although it is extremely difficult, it is possible to effectively achieve equivalent control of static pressure by applying vibrations perpendicular to the welding surface.

(Example of implementation) In order to realize a compound vibration welding tip, for example, as shown in Fig. 1, a bending vibration rod 1 whose vibration order differs depending on the vibration direction is used, and multiple longitudinal vibration systems, bending vibration systems, or torsional vibration systems are used. When driving by system 2.3, positions 1b and lc are vibration nodes of bending vibration in other vibration directions in the longitudinal vibration system and bending vibration system, and are near the abdomen of vibration in the driving direction.
Stable compound vibration can be obtained by driving at a bending vibration system, or by driving at a node in the direction of other vibrations and driving vibrations in a bending vibration system. The vibration order of the bending vibration system is 1d,
1e can be easily changed by changing the dimension in the vibration direction, for example, the thickness in the case of a rectangular cross section.

For example, in the case of a metal conducting wire 4 and a plate-shaped welding sample δ, the welding method is such that zero static pressure is applied to the stacked samples using the welding tip 1a, and the welding tip is subjected to compound vibration to control the vibration locus to perform the welding. conduct.

Further, the arrangement 2-3 of each vibration system for driving can be arbitrarily selected by appropriately combining longitudinal vibration, bending vibration, and torsional vibration systems with different vibration directions. For example, when orthogonal bending vibration rods are used, the vibration system will be arranged at a 90 degree angle if two vertical imaging systems are used, and the vibration system will be arranged at a 90 degree angle if a longitudinal vibration system and a bending vibration system or a bending vibration system are used. Can be placed parallel at an angle. Further, by driving a bending vibration system that vibrates in the length direction of the bending vibration rod, it is possible to apply vibration in the direction of static pressure perpendicular to the welding surface.

When each vibration system has the same frequency, it is possible to control the main direction of the vibration vector of the welding tip 1a by changing the vibration amplitude and vibration phase, and it is also possible to control the pattern of the vibration locus. be. When using vibration systems with different frequencies, random vibration trajectories can be obtained in each direction. Furthermore, by superimposing vibrations with different vibration frequencies on two or more longitudinal vibration systems with the same vibration frequency, a compound vibration welding tip can be obtained in which the main vibration direction of the welding tip can be changed and has random vibration components. is possible.

In order to facilitate the arrangement of a plurality of driving vibration systems 7.8, FIG. This is an example in which the vibration can be driven at the same position 6b or at different positions regardless of each other's vibrations. In addition, Figs. 3 and 4 show a compound bending vibration rod 9. - When using a free vibration rod, it is possible to shorten the length of the bending vibration rod, and for example, by driving from the top of the bending vibration rod with a longitudinal vibration system or a bending vibration system, vibration parallel to the static pressure can be applied. You can also do that.

FIG. 5 shows an example 16 in which a bending vibration and longitudinal vibration transducer or a torsional vibration and longitudinal vibration transducer is configured on a single axis, and it is possible to drive the composite bending vibration rod 15 at various vibration orders.
It is. Furthermore, by incorporating two bending perturbation transducers and changing the direction of vibration, it is possible to apply vibration parallel to the static pressure.

FIG. 6 shows an example in which the welding tip portion 18 at the tip of the vibration system 19 is a low-order vibration mode rod or a small tip. These various vibration transducers can be obtained by appropriately dividing an electrostrictive transducer such as PZT and polarizing it in a direction depending on the vibration mode.

(Effects of the Invention) As is clear from the above description, according to the present invention, the vibration locus of the welding tip is controlled by subjecting the welding tip to compound vibration and controlling the vibration amplitude and vibration phase of each vibration component. In addition, since it is possible to control the static pressure at the welding area as necessary, it is possible to realize uniform and highly stable joining and ultrasonic welding of the same or dissimilar materials regardless of the vibration direction. Become. Furthermore, if it is difficult to drive the welding sample when complex vibrations are simultaneously applied from the initial stage of joining, stable and non-directional joining can be achieved by controlling the application timing or drive waveform of each vibration.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a composite vibration welding tip using a composite bending vibrating rod with free-to-free ends at different drive positions using two vibration systems. Figure 2 is a drive using multiple vibration systems. Figure 3 is a schematic diagram of a composite vibration welding tip using a composite bending vibrating rod with both ends free and free at the same position. Figure 3 is a schematic diagram of a composite vibration welding tip using a composite bending vibration rod with fixed and free ends at different drive positions. , Fig. 4 is a schematic diagram of a compound vibration welding tip using fixed-free compound bending vibration rods with equal driving positions; A schematic diagram of a compound vibration welding tip using a vibration system with a uniaxial configuration of a longitudinal vibration transducer. Figure 6 is a schematic diagram of a compound vibration welding tip using a vibration system with a -axis configuration and with the tip as the welding tip. It is. 0... Static pressure applied to welding part 1... Composite bending vibration rod 1a... Welding tip part lb, lc... Drive part 1d, 1e... Bending vibration distribution 2.3... Ultrasonic vibration Converter 2a, 2d
... Vibration system node support flange 4.5 ... Welding sample 6 ... Composite bending vibration rod 6a ... Welding tip part 6b ... Drive parts 6c, 6d ... Quarter wavelength Bending vibration rod 7.8
... Ultrasonic vibration transducer 7-8 ... Ultrasonic vibration transducer installation angle 9 ・
... Composite bending vibration rod 9a ... Welding tip sections 9b, 9c ... Drive section 9d ... Additional mass 10.11 ... Ultrasonic vibration transducer 12 ...
Composite bending vibration rod 12a... Welding tip section 12b... Drive section 12c... Additional mass 13.14... Ultrasonic vibration transducer 15...
Composite bending vibration rod 15a... Welding tip section 15b... Drive section 16... - Shaft configuration compound ultrasonic vibration transducer 16a
, 16b, 16c---vibration converter 16ae, 16
be, 16ce - Drive electrode 17... Static pressure control vibration 18... Welding tip 18a... Welding tip portion 19... - Shaft configuration composite ultrasonic vibration transducer 2
0.21 ... Welding sample

Claims (4)

[Claims] (1) Control of the vibration trajectory of the welding tip by controlling the vibration amplitude and vibration phase of each complex vibration component using complex vibrations of the same frequency or different vibration frequencies with different vibration directions;
An ultrasonic welding method and device characterized by temporally controlling a driving period and a vibration locus pattern. (2) The ultrasonic welding device according to claim 1, wherein the compound vibration welding tip is constructed using a compound bending vibration rod. (3) The ultrasonic welding device according to claim 1, which is configured using a combination of longitudinal vibration, bending vibration, and torsional vibration systems. (4) The ultrasonic welding apparatus according to claim 1, characterized in that the static pressure is controlled equivalently by superimposing ultrasonic vibrations on the static pressure of the welding part.