JPH0443652A - Supersonic horn - Google Patents

Abstract

PURPOSE:To stabilize the vibration and amplitude of a supersonic horn by making the supersonic horn of amber, and choosing the axial length of the horn so as to meet the resonant mode of a particular wavelength and the axial length other than the straight horn part so as to meet the resonant mode of less than the particular wavelength. CONSTITUTION:In a supersonic horn structurally consisting of a conical (a) part 4 where a bonding device can be mounted at the tip thereof, a conical (b) part 2 that is formed into a large conical shape having a slope somewhat gentler than the conical (a) part 4, a straight horn part 10 that is formed into a cylindrical shape starting from the end face of the conical (b) part 2, the supersonic horn is made of amber, the whole axial length thereof is chozen so as to meet the resonant mode of a wavelength of 3/2, and a total axial length between the tip of conical (a) part 4 and the end face of conical (b) part 2 to meet the resonant mode of less than a wavelength of 2/6. With this, even when using amber the supersonic horn allows without generating any sub-resonance the vibrational direction of the bonding device in parallel to the axial direction of the horn axis that carries out axial vibration.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to semiconductor integrated circuits (IC) and large-scale integrated circuits (
The present invention relates to an ultrasonic horn used in a semiconductor assembly device for assembling semiconductor components of LSI.

[Background technology] In conventional semiconductor assembly equipment, multiple IC chips (semiconductors)
A lead frame for wire bonding, which is arranged in the longitudinal direction, is intermittently fed one pitch at a time by a transfer means that moves in the longitudinal direction, and this fed lead frame is transferred onto a bonding stage that is heated by a heater block. After that, the IC placed on the lead frame
The 1$f pole (pad) of the chip and the surrounding leads are bonded and connected by wires made of aluminum wire or gold wire. As a conventional ultrasonic horn used in this semiconductor assembly apparatus, one having the configuration shown in FIG. 3 is known.

That is, the ultrasonic horn shown in FIG. 3 includes a straight horn section 10, a cylindrical flange section 11 for mounting and fixing an ultrasonic transducer (electro-acoustic transducer), and a conical section 12.
and a bonding tool (capillary) 3.

The above ultrasonic horn is mainly made of stainless steel or titanium alloy, and as shown in Figure 3, the ultrasonic horn is made of hybrid IC.
To bond the pads on a large-area IC chip, such as a thermal head board, and the leads of a lead frame using wires, an In addition, it is necessary to configure the resonant mode with a length of approximately 3/2 wavelength (e) in consideration of the relationship with a recognition device such as a camera disposed above. Here, the 3/2 wavelength (e) resonant mode length is used because the frequency of the normally used ultrasound is 5.
For example, when the frequency is 60 kHz and the ultrasonic horn material is stainless steel, the axial length of 3/2 wavelength (λ) is about 125 m.
This is because it is appropriately configured to have a length of approximately m. Also,
The straight horn part 10 has a cylindrical shape, and has a nodal shape about 1/4 of the length of the end of the straight horn part 10.
A cylindrical flange portion 11 having a diameter larger than the outer circumference of the pawn is integrally formed at a point (nodal position of ultrasonic vibration). A cavity 11a is formed on the inner peripheral side of this cylindrical flange portion 11. Further, a threaded shaft 10a is provided at the end of the straight horn section 10, and an electro-acoustic transducer (ultrasonic transducer) consisting of a bolted Langevin type vibrator or the like that generates ultrasonic vibrations is connected to the screw of the shaft 10a. (sonic wave vibrator) are screwed together. The entire ultrasonic transducer to be coupled is securely fixed to the head portion of the main body via the cylindrical flange portion 11. In addition, the length of 2/2 from the end of the straight pawn part 10 (hereinafter simply 2/2
The conical part 1 is shaped like a cone toward the front (indicated by λ, etc.)
2 is formed. This conical portion 12 is for expanding the vibration amplitude of the ultrasonic vibration transmitted by the straight horn portion 10. The free end of the conical portion 12 is tapered to make it easier to attach the bonding tool 3. This bonding tool 3 is fixed using a fixing member such as a bolt through a hole 13 formed in a direction perpendicular to the axial direction of the ultrasonic horn.

In the bonding connection using the ultrasonic horn having the above configuration, the lead frame on the bonding stage with a heater block arranged on the bottom surface is overheated, and in this overheated state, the ultrasonic horn is moved vertically by a drive mechanism (not shown). The ball formed at the tip of the bonding tool 3 is crushed and pressed against the electrode (pad) of the IC chip by heating and crimping. At the same time as this crushing, ultrasonic vibrations are applied from an ultrasonic pawn.

However, when bonding an IC with a wide area such as a hybrid IC or a thermal head board, the area where overripe occurs is wide and the surrounding atmosphere temperature becomes higher than when the area is narrow. In addition, the ultrasonic horn is driven by an XY table in the X and Y directions, and is also configured to be able to swing in the vertical direction (Z-axis direction), so it can move between areas where the ambient temperature is high and low. That will happen.

Therefore, due to the influence of ambient temperature, conventional ultrasonic horns made of stainless steel or titanium alloy have the problem that the ultrasonic horn expands and contracts due to thermal expansion, causing the bonding position to shift. This requires sophisticated countermeasures against misalignment in a bonding ink device that performs positioning with micron precision.

Therefore, the material of this ultrasonic horn was changed to Invar material rather than stainless steel. This invar material is a type of nickel steel, and its semi-composition is C0120%, Mn015%, Ni36%, Fe
It is known for its small coefficient of linear expansion, and has a range of 0 to
It shows about 1xlO-'/deg at 40°C. This value is about 1/10 that of iron or nickel. In addition, the coefficient of thermal expansion of Zhao Amber to which cobalt and a small amount of manganese are added is lXl
0-'/deg.

The graph in Figure 4 shows the actual free admittance characteristics measured by constructing an ultrasonic horn as shown in Figure 3 using such amber material, where the horizontal axis represents the frequency (kHz).
z), the vertical axis is logarithmic and J: rearmittance characteristic (millimo) is shown.

[Problems to be Solved by the Invention] However, conventional ultrasonic horns use an amber material with a small coefficient of thermal expansion, but since this amber material is relatively soft compared to stainless steel etc., it is difficult to attach it to the tip of the horn. There is a drawback that stable fixing cannot be performed when holding the bonding tool 3 that has been attached. In addition, as shown in Figure 4, there is a sub-resonance (62, 12kHz) near the main resonance (62, 12kHz).
63°07kHz). This is because the vibration direction of the tip of the bonding tool 3 is not parallel to the straight horn portion 10 (including the conical portion 12) that generates longitudinal vibration, making the vibration amplitude of the ultrasonic wave unstable. In other words, ultrasonic vibrations generate longitudinal vibrations in the straight horn part 10 and conical part 12, and lateral vibrations in the bonding tool 3, but the straight horn part lO etc. receive the reaction force due to the lateral vibrations of the bonding tool 3. rotational moment is applied and lateral vibration is induced. As a result, the bonding tool 3 performs linear vibration or elliptical vibration with an inclination to the longitudinal vibrating horn shafts 10 and 12, resulting in poor bonding and poor fixation of the bonding tool.

Therefore, the present invention has been made in view of the above-mentioned drawbacks of the prior art, and it is possible to change the vibration direction of the bonding tool from the axial direction of the horn shaft that performs longitudinal vibration without causing sub-resonance even if an invar material is used for the ultrasonic horn. An object of the present invention is to provide an ultrasonic horn capable of performing parallel vibrations.

[Means for Solving the Problems] An ultrasonic horn according to the present invention has at least a conical portion formed in a substantially conical shape, and a straight horn portion formed in a cylindrical shape from an end face of the conical portion. A sonic horn, the ultrasonic horn being made of invar material and having a resonance mode length of 3/2 wavelength in the axial direction,
The axial length of the portion other than the straight horn portion is 276 wavelengths or less.

Further, the ultrasonic horn according to the present invention includes a conical 8 portion to which a bonding tool is attached to the tip, a conical 5 portion formed in a conical shape with a slightly larger slope than the conical 8 portion, and an end surface of the conical 5 portion. In an ultrasonic horn composed of a cylindrical shape, the ultrasonic horn is made of invar material and has a resonant mode length of 3/2 wavelength in the axial direction, The axial length of the conical 8 part and the conical 5 part is 2/6 wavelength or less.

[Example 1] Next, an example of the present invention will be described in detail with reference to the drawings. Note that components having the same configuration and functions as conventional ultrasonic pawns will be described using the same reference numerals.

FIG. 1 is a diagram showing the configuration of an ultrasonic horn according to the present invention.

In Figure 1, the ultrasonic horn is straight horn section 1.
, a cylindrical flange part 11 for attaching and fixing the ultrasonic bone, a conical 5 part 2, a conical 8 part 4 formed in front of the conical 5 part 2, and a bonding tool (
capillary) 3. In the configuration of this ultrasonic pone, the cylindrical flange part 11, the hollow 11a formed in the cylindrical flange part II, and the shaft 10a with a screw formed at the end of the straight horn part l are arranged as shown in FIG. Since it has the same configuration as , detailed explanation will be omitted.

The ultrasonic pawn is made of Invar material, and is configured such that its total length is a 3/2 wavelength resonance mode length (hereinafter simply referred to as 3/2 etc.).

The straight horn part 1 has a cylindrical shape, and has a diameter larger than the outer circumference of the horn at a nodal point (nodal position of ultrasonic vibration) about 1/4 from the end of the straight horn part 1. A cylindrical flange portion 11 is integrally formed. A cavity 11a is formed on the inner peripheral side of this cylindrical flange portion 11. Further, a threaded shaft 10a is provided at the end of the straight horn portion 11,
An electro-acoustic transducer C consisting of a screw on the shaft 10a and a bolted Langevin type vibrator that generates ultrasonic vibrations.
(ultrasonic transducer) are screwed together. The entire ultrasonic transducer to be coupled is securely fixed to the main body head portion using the cylindrical flange portion 11. In addition, the straight horn part l is formed to have a length of 2/2λ or more from the end in the axial direction, and includes a conical 8 part 4, a conical 5 part 2, and the remaining conical part 4 for fixing the bonding tool 3 attached to the tip of the horn. The structure is such that the straight horn part 1 is within 1/2L. The conical 5 part 2, which is formed in a conical shape toward the front of the straight horn part 1 and expands the vibration amplitude of ultrasonic vibration, is formed with approximately 1/6 diameter, and the conical 8 part 4 to which the bonding tool 3 is attached. It is also formed to be approximately 1/6 the size. This conical 8
The conical portion 4 is configured to have a gentler slope than the conical portion 2 in order to facilitate attachment of the bonding tool 3. The bonding tool 3 is fixed using a fixing member such as a bolt through a hole 13 formed in a direction perpendicular to the axial direction of the ultrasonic horn.

As mentioned above, the ultrasonic horn according to this embodiment has the conical 8 part 4 including the bonding tool 3, the conical 5 part 2, and a part of the straight horn part 1 so as to have a 1/2 wavelength (e). Since we have adopted a composite configuration, the main resonance (61, 22kHz) can be seen from the free admittance characteristics shown in Figure 2.
No sub-resonance occurs after 2). therefore,
The bonding tool 3 can be vibrated in a direction parallel to the bone axis of the straight horn part 1, etc., which performs longitudinal vibration.

The process of making a bonding connection using the ultrasonic horn is the same as the conventional process, so a description thereof will be omitted.

[Effects of the Invention] As explained above, according to the present invention, even when an invar material is used for the ultrasonic horn, the direction of vibration of the bonding tool can be made to vibrate in a direction parallel to the horn axis that performs longitudinal vibration. This has the effect of stabilizing the vibration amplitude of ultrasonic waves.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an ultrasonic horn according to the present invention, FIG. 2 is a diagram showing the admittance characteristics of the ultrasonic horn in FIG. 1, and FIG. 3 is a diagram showing the configuration of a conventional ultrasonic horn. FIG. 4 is a diagram showing admittance characteristics when amber material is used in a conventional ultrasonic horn. l...Straight horn part, 2...Conical 5 parts,
3... Bonding tool, 4... Conical a part, 1
0... Straight horn part, 11... Cylindrical flange part, 12... Conical part. Patent Applicant Kaiyo Denki Co., Ltd. Agent Patent Attorney Masaharu Hakiri No. 1 1...-S I-Rail I-1 Noto 4 ・Koni 1] Wa 0 Ji] 1 Yen V Fufuri I7 Ap No. 3 3 -... Ho' J de 4 nog '10a-! fl1 11a':

Claims (2)

[Claims] (1) An ultrasonic horn having at least a conical portion formed in a substantially conical shape and a straight horn portion formed in a cylindrical shape from an end face of the conical portion, the ultrasonic horn being made of an amber material and An ultrasonic horn having a resonant mode length of 3/2 wavelength in the axial direction, and an axial length other than the straight horn portion being 2/6 wavelength or less. (2) A conical part A to which a bonding tool is attached to the tip, a conical part B formed in a conical shape with a slightly larger slope than the conical part A, and a cylindrical shape formed from the end face of the conical part B. In the ultrasonic horn configured with a straight horn part, the ultrasonic horn is made of an invar material and has a resonance mode length of 3/2 wavelength in the axial direction, and the axial direction between the conical a part and the conical b part is An ultrasonic horn having a length of 2/6 wavelength or less.