TW201923940A - Bonding head for mounting components and die bonder with such a bonding head - Google Patents

Abstract

The invention relates to an engaging head for mounting a component and an engaging machine having such an engaging head, the engaging head (1) comprising a shaft (2) and a housing part (3) in which the shaft (2) is supported. The bearing of the shaft (2) rotates the shaft (2) about the axis (6) and displaces the shaft (2) by a predetermined stroke (H) in the longitudinal direction of the axis (6). The joint head further includes: an electric motor having a stator attached to the housing portion (3) and a rotor attached to the shaft (2); an encoder for measuring a rotational position of the shaft (2); and A force generator for applying a force to the shaft (2). The stator includes a coil (7) to which an electric current can be applied, and the rotor includes a plurality of permanent magnets (8). The length of the permanent magnet (8) measured in the longitudinal direction of the axis (6) is shorter than the effective length of the coil (7) measured in the longitudinal direction of the axis (6) by at least the stroke (H) or by at least the stroke (H) .

Description

   Bonding head for mounting components and die bonding machine with such bonding head   

The present invention relates to a bonding head for mounting a component (generally an electronic component or an optical component, particularly a semiconductor wafer and a flip chip) on a substrate. The installation process is also referred to as a joining process or an assembly process. The present invention also relates to a semiconductor mounting apparatus having such a bonding head and which is industrially known as a die bonding machine.

Automatic assembly machines with bonding heads of this type are used in particular in the semiconductor industry. Examples of such automated assembly machines are die bonders or pick and place machines that are used to place and bond components in the form of semiconductor wafers, micromechanics, and micro optical components to substrates such as lead frames, printed circuit boards , Ceramics, etc.). The pick-up position, in particular the suctioned component, is picked up by the bonding head, moved to the position of the substrate and placed on the substrate at a precisely defined position. The joint head is part of a pick and place system that allows movement of the joint head in at least three spatial directions.

The joint head includes: a shaft that can rotate about an axis and can move in a longitudinal direction of the axis; a driver that rotates the shaft; an encoder that measures a rotational position of the shaft, and a force A generator for applying a force to the shaft in a longitudinal direction of the axis. This shaft picks up the assembly directly or is configured for picking up a wafer holder, such as a "wafer chuck", configured for picking up the assembly.

The joint head used by the applicant includes a driver including an electric motor and a gear set formed by two gears, one of the two gears is attached to a shaft of the electric motor, and the other gear is attached To the shaft of the joint head.

The object of the present invention is to develop a joint head with which the rotational position of the shaft can be positioned with higher angular accuracy, and with the joint head, the shaft can be oriented in the longitudinal direction of the axis with as little force as possible. Move up.

1‧‧‧ joint head

2‧‧‧ axis

3‧‧‧shell

4‧‧‧ hole

5‧‧‧ end of shaft

6‧‧‧ axis

7‧‧‧coil

8‧‧‧ permanent magnet

9‧‧‧ disc

10‧‧‧Read head

11‧‧‧ cover

12‧‧‧ cavity

13‧‧‧ perforation

14‧‧‧ first drilling

15‧‧‧second drilling

16‧‧‧ tube

H‧‧‧ Itinerary

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the detailed description, serve to explain the principles and embodiments of the invention. The drawing is not drawn to scale.

In the drawings: Fig. 1 shows schematically and in section a first embodiment of a joint head, Fig. 2 shows a magnet arrangement for a rotor of an electric motor in the joint head, Figs. 3 and 4 The length ratio is exemplified, FIG. 5 shows the joint head with aerodynamic generator schematically and in section, and FIG. 6 shows the joint head with aerodynamic generator and air bearing schematically and in section. Fig. 7 shows schematically and in section a joint head with an integrated temperature control device, and Fig. 8 schematically shows a driver for the joint head.

    [Example]    

FIG. 1 schematically shows a cross section of the joint head 1. The joint head 1 includes a shaft 2 and a housing portion 3, and the shaft 2 is supported in the housing portion 3. The shaft 2 contains a hole 4 which leads to the end 5 of the shaft 2 and can be supplied with a vacuum. The end 5 of the shaft 2 is configured to receive a component or a wafer holder for the component. The bearing of the shaft 2 allows the shaft 2 to rotate about the axis 6 and allows the shaft 2 to be displaced by a predetermined stroke H in the longitudinal direction of the axis 6 (FIG. 3). The diameter of this shaft 2 can have different grades in its length, as shown in FIGS. 1, 5 and 6. The joint head 1 further includes: a driver configured to rotate the shaft 2 about the axis 6; an encoder configured to measure a rotational position of the shaft 2; and a force generator, the force generator It is configured to apply a force to the shaft 2 in the longitudinal direction of the axis 6. The force is, for example, a predetermined pickup force when a component is picked up or a predetermined bonding force when a component is mounted on a substrate.

The driver is an electric motor including a stator and a rotor, the stator is attached to the housing portion 3, and the rotor is attached to the shaft 2. The stator includes a coil 7 capable of being supplied with current, and the rotor includes a plurality of permanent magnets 8.

In principle, the electric motor is a commercially available electric motor, which is improved for the purpose of the present invention, so that the length of the permanent magnets 8 is shortened by at least the stroke H. This improvement reduces torque, but is technically simple and has the advantage that at the same time the mass of the rotor becomes smaller, or can be reduced or even minimized at the expense of torque. Alternatives to extend the length of the coils 7 by at least the stroke H are also possible, but not preferred. As shown in FIG. 2, the permanent magnets 8 are flat parallelepiped magnets, in which two opposite largest surfaces of the permanent magnets 8 are magnetized into a north pole N and a south pole S. The permanent magnets 8 are arranged on a circle. The largest areas facing the center of the permanent magnets 8 are the north pole N and the south pole S alternately. The largest regions of the permanent magnets 8 facing away from the center of the circle are alternately the south pole S and the north pole N.

The electric motor is used to rotate the shaft 2 about the axis 6. Since the shaft 2 must be able to be displaced in the longitudinal direction of the axis 6, the length L1 (FIG. 3) of the permanent magnets 8 is shorter than the effective length L2 of the coils 7 by at least the stroke H or longer than the effective length of the coils 7. L2 has a long stroke H such that the force exerted by the coils 7 on the permanent magnets 8 is independent of the position occupied by the shaft 2 along the longitudinal direction of the axis 6. The coil 7 has a predetermined mechanical length L3 in the longitudinal direction of the axis 6. The effective length L2 indicates that the length in the magnetic field generated by the current flowing through the whole of the coil 7 and rotating the permanent magnets 8 around the axis 6 provides a major part of the force acting on the permanent magnets 8. Therefore, the effective length L2 is shorter than the mechanical length L3. FIG. 3 illustrates a case where the length L1 of the permanent magnets 8 is shorter than the effective length L2 of the coil 7 by a stroke H, and FIG. 4 illustrates that the length L1 of the permanent magnets 8 is longer than the effective length L2 of the coil 7. In the case of stroke H. So L ₁ L ₂ -H or L ₁ L ₂ + H

In the first case, the permanent magnets 8 (and therefore the rotor) remain in the magnetic field of the coils 7 even during the axial displacement of the shaft 2 along the axis 6; in the second case The permanent magnets 8 extend beyond the coils 7 during the entire axial displacement. During the axial displacement of this shaft 2, in both cases a very small force or a change in force acting along the axis 6 occurs at most.

The encoder is configured to measure the rotational position of the shaft 2. The encoder is preferably formed by a disc 9 and an encoder reading head 10 which is attached to the shaft 2 and has an encoder scale attached to the edge of the disc 9, the encoder The read head 10 is attached to the joint head 1, preferably, to the housing portion 3 of the joint head 1. The encoder scale has a short line extending in the longitudinal direction of the axis 6. The length of the short line measured in the longitudinal direction of the axis 6 matches the measurement range of the encoder reading head 10 extending in the longitudinal direction of the axis 6 so that the short line is located over the entire stroke H of the shaft 2 Within the measuring range of the encoder reading head 10.

The angle sensor can also be used as an encoder, such as a magnetic angle sensor, which determines the rotation position based on the magnetic field generated by the permanent magnet 8 or the optical angle sensor or any other angle sensor .

A force generator is used to generate picking and engaging forces. For example, a mechanical force generator can be used as a force generator, particularly a force generator in which a spring is used, which acts on the shaft 2 to generate a force acting in the longitudinal direction of the axis 6. Aerodynamic generators can also be used as force generators, as is the case with the joint head 1 schematically in FIGS. 5 and 6 and shown in section. Here, the housing part 3 and the cover 11 placed on the housing part 3 together with the shaft 2 form a closed cavity 12 whose volume changes during the longitudinal movement of the shaft 2. The cover 11 includes a perforation 13 through which the cavity 12 can be pressurized with compressed air. The cavity 12 thus forms a pressure chamber, and the pressure prevailing in the pressure chamber generates a force acting on the shaft 2. The movement of the shaft 2 in the longitudinal direction of the axis 6 (that is, the stroke H) is limited by, for example, a stop. On the one hand, in the no-load state, the force generated by the force generator presses the shaft 2 against the stop. On the other hand, since the shaft 2 is pushed away from the stop during picking and engaging, the force acts on the component as a picking force when the component is picked up, and as the engaging force when the component is lowered. The movement of the shaft 2 during these processing steps is a passive movement due to the fact that the shaft 2 becomes stationary when the shaft 2 falls on the component and when the component falls on the substrate, and is driven by the drive 17 (FIG. 8 The engagement head 1 driven by) is further lowered until a touchdown is detected, and the driver 17 stops.

The bearing of the shaft 2 in the housing portion 3 may be, for example, a plain bearing, a ball bearing, an air bearing, or another suitable bearing. In the exemplary embodiment shown in FIG. 5, the shaft 2 is supported in the housing portion 3 by a sliding bearing, and in the exemplary embodiment shown in FIG. 6, the shaft 2 is supported by an air bearing. In the case of the air bearing, the housing portion 3 has an air inlet for supplying compressed air. In a preferred design of the air bearing, the housing portion 3 also has an air outlet for removing air from the air bearing. For example, the air inlets are first holes 14 and, for example, the air outlets are second holes 15. If there are air inlets and air outlets, they are located between some of the outlets in the longitudinal direction of the axis 6. The air outlets can be connected to the environment such that the ambient pressure is applied to the air outlets, or a vacuum can be applied to the air outlets to suck out air forced into the air bearings through the air inlets. The flow direction of the air in the air inlets and the air outlets is shown by (laterally offset) arrows in FIG. 6. With this configuration in which the air inlet is surrounded by the air outlet, a part of the air that has been pressed into the gap between the shaft 2 and the housing portion 3 through the air inlets is prevented from reaching the cavity 12 and thus changed on the axis The force acting on the shaft 2 in the longitudinal direction of 6.

Fig. 7 shows schematically and in section a joint head with a temperature control device. This temperature control device is used to maintain the temperature of a predetermined part of the bonding head 1 at a predetermined value. The temperature control device comprises, for example, a tube 16 which is advantageously integrated into the housing part 3 as shown, and which is part of a closed thermal circuit through which the fluid flows, the temperature of the fluid Controlled to a predetermined value in an external heating or cooling or heating and cooling device. The fluid can be gaseous or liquid. In a specific case, the temperature control device is an electric heating resistor integrated in the case portion 3. This temperature control device can be used with all joint heads 1. For example, on the joint head 1 having a pneumatic generator, the temperature control device can be used to control the temperature in the pressure chamber to a predetermined value so that the force generated by the force generator is independent of changes in the ambient temperature.

The bonding head according to the present invention is generally used in a semiconductor mounting apparatus which is industrially known as a die bonding machine. This semiconductor mounting apparatus includes a driver 17 configured to move the joint head 1 in the longitudinal direction of the axis 6. When the assembly is picked up and when the assembly is engaged, the engagement head 1 is lowered by the driver 17, whereby the shaft 2 is passively carried.

The joint head offers several advantages, namely:

-The drive for rotating the shaft according to the present invention is a direct drive, and therefore a backlash-free drive, in which the rotor is directly attached to the shaft, which enables backlash-free and therefore high accuracy Move to the rotation position of the shaft. This is in contrast to known joints where the gear is interposed between the drive and the shaft.

-The measurement of the rotational position of the shaft is direct and free of play because the encoder scale is mounted on and attached to the disc of the shaft.

-In the absence of gears and toothed belts, the direct drive of the shaft is wear-free and does not cause any wear. This is particularly advantageous in a clean room environment where abrasion may damage the integrated circuit (IC) and cause semiconductor wafers to be contaminated with particles.

-The axial displacement of the shaft, i.e. the displacement of the shaft along its longitudinal axis is essentially forceless. This means that during the establishment of the picking or engaging force, the displacement of the shaft along the longitudinal axis does not produce any additional force that increases or decreases the force generated by the force generator. This is in contrast to known joints that insert a gear or toothed belt between the drive and the shaft.

-The design is space-saving, compact, and allows relatively large bonding forces required for the mounting of semiconductor components in a small space and with a small weight.

-The mass of the shaft including the rotor is very small. When the shaft hits a component, the temporary force exerted on the component is proportional to the momentum, that is, the product of the shaft's mass and speed, and must not exceed a predetermined value, otherwise the component may be damaged. The smaller mass allows higher speeds and therefore results in shorter cycle times.

-The design of the joint head with air bearing allows almost frictionless rotation and displacement of the shaft.

-The design of the bonding head with a temperature control device makes it possible to minimize or eliminate the influence of ambient temperature fluctuations on the bonding head and therefore the bonding process.

Although embodiments and applications of this invention have been shown and described, it will be apparent to those skilled in the art having the benefit of this disclosure that more can be done than described above without departing from the inventive concepts herein. Modifications. Therefore, the present invention is not limited except by the scope of the appended patent applications and their equivalents.

Claims (10)

    A joint head (1) for mounting a component on a substrate includes a shaft (2), a housing portion (3), the housing portion (3) including a bearing for the shaft (2), and the bearing The shaft (2) is allowed to rotate about the axis (6) and the shaft (2) is moved about a predetermined stroke (H) in the longitudinal direction of the axis (6), a drive configured to make the shaft (2) Rotating around the axis (6), the encoder is configured to measure the rotational position of the shaft (2), and the force generator is configured to move in the longitudinal direction of the axis (6). The shaft (2) exerts a force, wherein the driver is an electric motor including a stator and a rotor, wherein the stator is attached to the housing portion (3), and the rotor is attached to the shaft (2), the The rotor includes a plurality of permanent magnets (8), and the stator includes a coil (7) to which an electric current can be applied, wherein the permanent magnet is caused by a magnetic field generated by an entire current flowing through the coil (7) ( 8) Rotation about the axis (6), and the length (L1) of the permanent magnet (8) measured in the longitudinal direction of the axis (6) is longer than the line measured in the longitudinal direction of the axis (6) The effective length (L2) of the turn (7) is at least the stroke (H) shorter or at least the stroke (H) longer.         The joint head as claimed in claim 1, wherein the encoder comprises a disc (9) and an encoder reading head (10), the disc (9) is fixed to the shaft (2) and has an attachment to the circle An encoder scale at the edge of the disc (9), wherein the encoder scale has a short line extending in the longitudinal direction of the axis (6), and the length of the short line measured in the longitudinal direction of the axis (6) and The measurement areas of the encoder read head (10) extending in the longitudinal direction of the axis (6) match each other, so that the short line is located on the encoder read head (2) over the entire travel (H) of the shaft (2). 10) in the measurement area.         As in the joint head of claim 1, wherein the force generator is a pneumatic generator, the aerodynamic generator has a pressure chamber, and compressed air can be supplied to the pressure chamber, in which the predominant pressure acts On the end of the shaft (2).         As in the joint head of claim 2, wherein the force generator is a pneumatic generator, the aerodynamic generator has a pressure chamber, and compressed air can be supplied to the pressure chamber, and the pressure effect in the pressure chamber is dominant. On the end of the shaft (2).         The joint head of claim 1, wherein the bearing is an air bearing, wherein the housing portion (3) has an air inlet for supplying compressed air and an air outlet for removing air from the air bearing, wherein the air The inlet is arranged in the longitudinal direction of this axis (6) between some of the air outlets.         The joint head of claim 2, wherein the bearing is an air bearing, wherein the housing portion (3) has an air inlet for supplying compressed air and an air outlet for removing air from the air bearing, wherein the air The inlet is arranged in the longitudinal direction of this axis (6) between some of the air outlets.         The joint head of claim 3, wherein the bearing is an air bearing, wherein the housing portion (3) has an air inlet for supplying compressed air and an air outlet for removing air from the air bearing, and waits for the air The inlet is arranged in the longitudinal direction of this axis (6) between some of the air outlets.         The joint head of claim 4, wherein the bearing is an air bearing, wherein the housing portion (3) has an air inlet for supplying compressed air and an air outlet for removing air from the air bearing, wherein the air The inlet is arranged in the longitudinal direction of this axis (6) between some of the air outlets.         The joint head according to claim 2, further comprising a temperature control device for maintaining a temperature of a predetermined part of the joint head (1) at a predetermined value.         A die bonding machine having a bonding head as claimed in any one of claims 1 to 9, the die bonding machine having a driver (17) configured such that the bonding head (1) is on the axis (6) Move in the longitudinal direction.