HK1225689B - Apparatus for the isolated application of solder material deposits - Google Patents

Description

Equipment for individually applying solder bumps

Technical Field

The present invention relates to a device for individually applying solder piles, in particular solder balls, comprising a conveying device for individually conveying the solder piles from a solder container to an application device, wherein the conveying device comprises a transport receiving portion configured as a through-hole, which can be moved from a receiving position P1 to a transfer position P2, in which the solder piles are received from the solder container, and in which the solder piles are acted upon by compressed gas and are transferred from the transfer position to an application position P3, to an application opening of an application nozzle of the application device.

Background Art

A device of the type mentioned above is known from DE 195 41 996 A1. This device has a detector device for triggering the application of a solder deposit in the application position, the detector device being designed as a pressure sensor. The pressure sensor detects the excess pressure that builds up in the application channel, which occurs when the application opening is closed by the solder deposit in application position P3. When the solder deposit is in application position P3 and blocks the application opening, laser application is triggered in a controlled manner via the pressure sensor when a defined switching pressure is reached.

When using the known device, a clear application position of the solder is determined by the fact that the solder bead is already in contact with the connection surface of the substrate to be provided with the solder bead before the application of laser radiation, so that the application opening is blocked and the pressure sensor provides a corresponding sensor output signal for triggering the laser application. In other words, the detector device of the known device, which is designed as a pressure sensor, is used not only to trigger the laser application but also to detect the position of the solder bead. In other words, the detector device of the known device only provides information about whether the solder bead is in the application position and, therefore, whether laser application of the solder bead can take place.

Summary of the Invention

The invention is based on the object of proposing a device of the type mentioned at the outset, which enables a more precise control of the laser loading.

According to the invention, the device is provided with a first detector device for triggering the application of laser radiation to the solder bead in the application position P3, wherein the laser light is emitted by the laser device, and a second detector device for detecting the position of the solder bead.

The provision of a second detector device enables precise control of the laser loading, which, in addition to the first detector device for triggering the laser loading, provides information about the position of the solder accumulation that is independent of the first detector device, since the method by which the laser loading is performed can thus be based on the position of the solder accumulation.

In a preferred embodiment of the device according to the invention, in contrast to known devices that use a pressure sensor for triggering the laser application, a reflection sensor is used in the first detector device, which is designed as an optical sensor device, and detects reflected radiation reflected by the solder accumulation. This allows the laser device, which is used as an energy source for applying melting energy to the solder accumulation, to simultaneously provide the medium, namely the laser radiation, so that the solder can be detected by means of the optical sensor. A pressure sensor is used as the second detector device, but it is not used to trigger the laser application, but rather to detect the position of the solder accumulation. A high pressure output signal of the pressure sensor indicates that the solder accumulation closes the application opening, i.e., is still located within the application device, while a low pressure output signal of the pressure sensor indicates that the application opening is free, i.e., the solder accumulation is already located on the connection surface of the substrate.

During operation of the device according to the invention, the laser device is operated in at least two power levels. In the first power level, a so-called "pilot beam" with a relatively low energy density is emitted. This pilot beam, when impinging on the solder bead in the application opening, generates reflected radiation that is detected by a reflection sensor. If, based on the detection of the reflected radiation by the reflection sensor, it is determined that the solder bead is in application position P3, then in the second power level of the laser device, the solder bead is impinged with laser radiation having a significantly increased energy density. This laser radiation at least partially melts the solder bead, thereby enabling it to be discharged from the application device using compressed gas. Due to the release opening, a pressure drop occurs that can be determined by a pressure sensor. This pressure drop defines the precise time at which the application opening is released, thereby enabling, for example, the relationship between the laser power and the time at which application occurs at the connection surface to be determined.

It is also particularly advantageous if the first detector device, in addition to a reflection sensor that detects reflected radiation from the solder accumulation in the application opening of the application nozzle, also includes an optical temperature sensor that detects infrared radiation emitted by the solder accumulation. By integrating the optical temperature sensor into the detector device, the detector device can be used not only to trigger laser application of the solder accumulation by the laser device but also to determine the temperature of the solder accumulation. The temperature of the solder accumulation can, in particular, be used to optimize the parameter settings of the laser device based on an empirically determined relationship between the temperature of the solder accumulation and its melting state. If the corresponding temperature output signal is then superimposed on the pressure output signal of the pressure sensor of the second detector device, for example, compressed gas application can be performed to discharge the solder accumulation from the application opening depending on the temperature of the solder accumulation, i.e., its melting state.

In particular, if the temperature sensor is connected to the laser device's control unit so that the control unit controls the laser device's operation based on the temperature sensor's output signal, the laser device can be optimized on-site, i.e., during system operation. Thus, for example, if the temperature of the solder deposit is too high, the laser device's power can be reduced.

In a preferred embodiment, the first detector device is designed independently of the application device and is optically connected to the application opening of the application nozzle by means of a coupling device. This allows the first detector device to be arranged independently of the device, so that the first detector device does not necessarily need to be mounted on the device housing. Consequently, the housing, and in particular the application device, can be designed relatively simply.

It has proven particularly advantageous if the coupling device is used not only for the optical connection between the application opening and the first detector arrangement but also for the optical connection between the application opening and the laser arrangement, so that the design of the device can be further simplified due to the multiple functions of the coupling device.

When the coupling device is arranged on the upper side of the upper housing part of the device at the upper end of the application channel opposite the application opening and has not only a transparent coupling surface for establishing an optical connection between the application opening and the laser device but also a beam deflection device for deflecting the reflected radiation reflected by the solder pile to the first detector device, on the one hand, a compact construction of the coupling device is obtained, and on the other hand, the coupling device is arranged exposed on the upper side of the housing, so that the first detector device can be arranged arbitrarily around the device.

If the coupling surface is formed by the beam deflection device, a particularly simple design of the coupling device results. In particular, the dual function of the beam deflection device allows for a miniaturized design of the coupling device, which facilitates the device in particular with regard to a desirable weight reduction.

A particularly compact and simple design of the beam deflection device explained above, which can perform a dual function, can be achieved by forming the beam deflection device as a semi-transparent mirror which is arranged at an angle of 45° to the optical axis between the laser device and the application opening.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings show:

FIG1 shows an isometric view of an apparatus for individually applying solder deposits;

FIG2 shows a cross-sectional view of the apparatus shown in FIG1 ;

FIG3 shows a top view of the conveying device of the apparatus shown in FIG2 ;

FIG. 4 shows a plan view of the device housing of the device shown in FIGS. 1 and 2 .

DETAILED DESCRIPTION

1 and 2 show an apparatus 10 for individually applying solder beads 11, wherein the solder beads 11 are in the present case designed as solder balls, which are stored in a solder container 12, which is arranged on the top 13 of an upper housing part 14 of an apparatus housing 15. A solder channel 17 is formed in the upper housing part 14 below a connection opening 16 (FIG. 4). This channel allows, as shown in FIG1 , the solder beads 11 to pass from the solder container 12 to a transport receptacle 18 (FIG. 3) designed as a through-hole of a conveyor device 19 designed as a circular conveyor disc, which is accommodated in a circular conveying space 21 between the upper housing part 14 and the lower housing part 20. To form the circular conveying space 21, a housing ring 22 is arranged concentrically with the conveyor device 19 between the upper housing part 14 and the lower housing part 20.

A conveyor shaft 24 is located in the housing upper part 14 and can be coupled at its drive end 23 to a motor drive (not shown in detail here). The conveyor shaft can drive the conveyor device 19 in rotation about an axis of rotation 28 via a drive pin 26 arranged at its output end 25, which engages in a coupling opening 27 of the conveyor device 19 shown in FIG. 3 .

As shown in FIG3 , in addition to the transport receiving parts 18 arranged equidistantly on the transport circle 29 of the transport device 19 , the transport device 19 also has a control circle 30 , which is concentrically and in the present case arranged within the transport circle 29 and has a control hole 31 on a common radial axis 50 with the transport receiving part 18 . The control hole 31 interacts with a light barrier device (not shown in detail) arranged in the device housing 15 and enables control of the clocked circular conveying movement of the conveying device 19 about the rotation axis 28, so that in the conveying direction 32 of the conveying device 19, the transport receiving part 18 moves forward in the conveying direction 32 from the receiving position P1 below the solder channel 17 connected to the solder container 12 by the division t of the conveying circle 29 and reaches the transfer position P2, in which the transport receiving part 18 is arranged coaxially or aligned with the transport channel 41 formed in the housing lower part 20, which extends from the transfer position P2 to the application device 33 and opens into the application channel 35 of the application device 33 via the output end 34.

2 , the application device 33 has, at its lower end, an application nozzle 36 that is replaceably arranged on the housing lower part 20 and has an application opening 37. In the present case, the application opening is configured to have a smaller diameter than the diameter of the solder accumulation 11, so that the solder accumulation 11 transferred from the transfer position P2 to the application nozzle 36 abuts against the opening edge of the application opening 37 in the application position P3. In the present case, the application nozzle 36 is screwed to the housing lower part 20 by means of a lock nut 62, wherein the connection of the application nozzle 36 to the housing lower part 20 has a seal 58 for sealing relative to the housing lower part 20.

A coupling device 38 is provided at the upper end of the application channel 35 on the upper side 13 of the device housing 15, said coupling device being provided with a transparent coupling surface 39. Via the coupling surface 39, the solder deposit 11 in the application position P3 can be impinged with laser radiation 40 emitted by a laser device (not shown in detail here).

The coupling surface 39 is formed in this case by the upper side of a semi-transparent mirror 63 , which is arranged at an angle α=45° on an optical axis 64 running between the application opening 37 and a laser device (not shown in detail here) that emits the laser radiation 40 .

2 , the solder bead 11 is located in the application position P3 at the application opening 37 . The solder 11 rests against the inner opening edge of the application opening 37 .

As shown in FIG2 , the coupling device 38, which is arranged on the upper side 13 of the housing upper part 14 at the upper end of the application channel 35 opposite the application opening 37, has a radiation channel 65 arranged coaxially with respect to the optical axis 64 and a reflection channel 66 arranged perpendicular to the optical axis 64. A semi-transparent mirror 63, with a reflection surface 67 formed by the underside of the mirror 63, is arranged at the intersection S of the reflection channel 66 and the radiation channel 65. A detector device 69 is arranged on the reflection axis 68, which is arranged at a reflection angle β=90° relative to the optical axis. The detector device has a reflection sensor 70 and a temperature sensor 71 and is designed in the present case independently of the device housing 15.

When the solder pile 11 in the application position P3 is loaded with laser radiation 40 emitted by a laser device, at least partial reflection of the laser radiation 40 is achieved on the surface of the solder pile 11, so that the reflected radiation 72 reflected by the solder 11 is reflected onto the reflection surface 67 of the semi-transparent mirror 63 and from the reflection surface along the reflection axis 68 to the detector device 69, in which the reflected beam 72 is split into a reflection sensor beam 73 that is radiated onto the reflection sensor 70 and a temperature sensor beam 74 that is radiated onto the temperature sensor 71 with the aid of a beam splitter which is also configured as a semi-transparent mirror 75 in this case.

During operation of the device, the laser device is operated in two power levels, so that the laser radiation 40 is emitted in a first power level as a pilot beam with a relatively low energy density, which is reflected as reflected radiation 72 by the solder pile 11 in the application position P3 and impinges on the reflection sensor 70 as a reflected sensor beam 73.

When it is determined that solder accumulation 11 is located at application position P3 based on the detection of reflected radiation 72 by reflection sensor 70, the laser device is switched to a second power level, in which laser radiation 40 is emitted as power radiation with an increased power density, in a manner triggered by reflection sensor output signal 76. The power radiation causes at least partial melting of solder accumulation 11, wherein the infrared radiation portion contained in reflected radiation 72 is detected by temperature sensor 71 and a corresponding temperature sensor output signal 77 is generated. Temperature sensor output signal 77 enables the temperature of solder accumulation 11 to be determined, so that temperature sensor output signal 77 can be used, for example, to set the power and/or pulse duration of laser radiation 40 as required to achieve a desired temperature and a desired melting state of solder accumulation 11.

The solder deposit 11 , which is at least partially melted by the laser exposure, is ejected by means of compressed gas via the transport channel 41 opening into the application channel 35 through the application opening 37 and applied to the contact surface 51 of the substrate 52 .

The compressed gas application can be carried out, for example, as follows: after the solder accumulation in the application position P3 is detected by the reflection sensor 70 and after a predetermined time interval for applying the power radiation to the solder accumulation 11 has elapsed, the compressed gas application is triggered.

Of course, it is also possible to operate the device in such a way that the pressurized gas application is dependent on the determination of a defined melting state of the solder deposit 11 via the temperature sensor 71 .

For pressurizing with compressed gas, the housing upper part 14 has a compressed gas connection 42 shown in Figures 1 and 4, which is connected via a compressed gas channel 43 to a solder pile receiving space 53 formed in the housing upper part 14 above the transfer position P2 and opposite the upper end of the transport channel 41 formed in the housing lower part 20. By applying compressed gas to the solder pile 11 arranged in the solder pile receiving space 53, the solder pile 11 is also transported to the application position P3 at the application opening 37 of the application nozzle.

As further shown in FIG2 , in addition to first detector device 69, a second detector device 80 is provided, which has a pressure sensor 44, which is connected via a pressure opening 45 to a pressure chamber 61 defined in application channel 35 of application device 33 between application opening 37 and a transparent, gas-tight partition 60, which is arranged at the lower axial end of housing 46 of coupling device 38. Pressure sensor 44 detects the pressure drop that occurs in pressure chamber 61, which occurs when application opening 37 is freed again after discharge of solder deposit 11, which has been at least partially melted by laser application, i.e., solder deposit 11 is no longer in application position P3, but is in its contact position on contact surface 51 of substrate 52.

Based on the information thus obtained about the position of the solder bead 11, the solder bead 11 can now be laser-applied again, wherein the application of the pilot beam and the evaluation of the reflection sensor output signal 76 generated by the first detector device 69 allow conclusions to be drawn about the surface shape of the solder bead 11 connected to the contact surface 51, since the reflection properties of a concave surface differ from those of a convex surface. In principle, the portion of the reflected radiation 72 that reaches the detector device 69 from the concave surface of the solder bead 11 through the application opening 37 is smaller than the portion of the reflected radiation 72 that reaches the detector device 69 from the convex surface of the solder bead 11 through the application opening 37.

The information obtained from the surface shape of the solder pile 11 applied to the contact surface 51 can be used to change the laser power in the second power level, i.e., when emitting a power beam to melt the solder pile 11 in the application opening 37 in the application position P3, so that the desired surface shape of the solder pile 11 applied to the contact surface in the contact position is achieved after the solder pile 11 is discharged from the application opening 37.

Claims (9)

1. An apparatus for individually applying solder deposits to contact positions on contact surfaces (51) of a substrate (52), the apparatus comprising: A conveying device for individually conveying the solder pile from the solder container to the application device, wherein the conveying device has a transport receiving section configured as a through hole, the transport receiving section being movable from a receiving position P1 to a conveying position P2, in which the solder pile is received from the solder container, in which the solder pile is loaded with compressed gas in the conveying position P2, and the solder pile is conveyed from the conveying position P2 to the application position P3, and conveyed to the application opening of the application nozzle of the application device; A first detector device is configured to trigger the loading of a solder pile at the application position P3 with laser radiation, wherein the laser radiation is emitted by a laser device; and A second detector device is used to detect the position of the solder pile. The first detector device is configured as an optical sensor device including a reflection sensor, which detects reflected radiation reflected by the solder pile at the application position P3 and at a contact position different from the application position P3. Furthermore, the second detector device includes a pressure sensor that measures the gas pressure in the pressure chamber formed between the transport receiving section located at the transport position P2 and the application opening of the application nozzle in the application device. In the event of a pressure drop in the pressure chamber (61) via the pressure sensor, the transfer of the solder pile from the application position P3 to the contact position is signaled to the control device of the laser device. 2. The device according to claim 1, Its features are, The first detector device (69) has an optical temperature sensor (71) in addition to the reflection sensor (70), the reflection sensor detects reflected radiation (72) reflected by the solder pile (11) in the application opening (37) of the application nozzle (36), and the temperature sensor detects infrared radiation emitted by the solder pile. 3. The device according to claim 2, Its features are, The temperature sensor (71) is connected to the control device of the laser device, so that the control device controls the operation of the laser device according to the output signal (77) of the temperature sensor. 4. The device according to any one of claims 1 to 3, Its features are, The first detector device (69) is constructed independently of the application device (33) and is optically connected to the application opening (37) of the application nozzle (36) by means of a coupling device (38). 5. The device according to claim 4, Its features are, The coupling device (38) is used not only for optical connection between the application opening (37) and the first detector device (69), but also for optical connection between the application opening and the laser device. 6. The device according to claim 5, Its features are, The coupling device (38) is disposed on the upper side (13) of the housing component (14) of the device, opposite the upper end of the application channel (35) and the application opening (37). The coupling device has not only a transparent coupling surface (39) for establishing an optical connection between the application opening and the laser device, but also a beam deflection device for deflecting the reflected radiation (72) to the first detector device (69). 7. The device according to claim 6, Its features are, The coupling surface (39) is formed by the beam deflection device. 8. The device according to claim 7, Its features are, The beam deflection device is configured as a semi-transparent mirror (63), which is positioned at a 45° angle relative to the optical axis (64) between the laser device and the application opening (37). 9. The device according to any one of claims 1 to 3, Its features are, The solder pile is solder balls.