Workpiece transfer apparatus

A workpiece transfer apparatus includes a nozzle unit and an imaging unit. The nozzle unit includes a tubular body, a suction hole opening at one end of the tubular body and an end face member of a transparent body sealing the other end of the tubular body. The imaging unit captures images of first patterns for positioning that are located on an upper surface of a workpiece. The size and shape of the suction hole fits within an outline of the upper surface of the workpiece. The end face member of the transparent body maintains a negative pressure inside the cylindrical body and permits optical penetration for the imaging unit. The imaging unit captures the image of the first pattern for positioning of the workpiece while the imaging unit views a suctioned surface of the workpiece through the transparent body and the suction hole.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a workpiece transfer apparatus, a workpiece mounting apparatus and a workpiece mounting method. In the transfer apparatus the workpiece, for example an electronic device such as a bare chip IC is transferred, and in the mounting apparatus the workpiece is mounted on a substrate.

2. Description of the Related Art

PCT international Application Laid-Open No. WO2003/041478 discloses a mounter in which a pattern for positioning of a workpiece and a pattern for positioning of a substrate are in the same direction and imaged at the same time through a transmissive outside part of an suction hole of a transparent nozzle when the mounter mounts the workpiece on the substrate using the transparent nozzle to pick up by negative pressure. Japanese Patent Application Laid-Open No. 2004-069612 is discloses a configuration in which an opening of a directional lighting device having both directional and diffusional characteristics is positioned on the same axis of an optical axis of a camera. Japanese Patent Application Laid-Open No. 10-308431 discloses a configuration which enables both to pick up a workpiece and to recognize the workpiece visually from upside by means of using a transparent nozzle.

Generally, a plurality of electronic devices especially bare chip ICs etc. is made of a wafer200formed and arranged a matrix of laminated patterns thereon as shown inFIG. 5, and each semiconductor component with the patterns is made by cutting the wafer200along cutting lines201. Usually a predetermined width from the cutting line201is remained as a cutting margin on which any pattern or the like is not formed for stabilization of yield in the cutting process as shown inFIG. 6.

Generally, a positioning mark for detecting a position of the electronic device is formed with a high degree of accuracy because the positioning mark is formed in the same process (photolithography etc.) of the pattern of the electronic device. Further, instead of the positioning mark, the pattern on a surface of the electronic device is often used as a fiducial mark, too.

Many electronic devices (hereinafter “workpieces”) became to be reduced size, and recently the size of some workpiece became to be less than 0.2 mm square. By necessity, a hole diameter of a workpiece pickup nozzle of a mounting apparatus is necessary to be less than one side of the workpiece.

Further, the hole diameter of the suction hole of the transparent nozzle is necessary to be more reduced diameter so as not to interfere with the pattern for positioning (as the fiducial mark) of the workpiece, if the method which disclosed in WO2003/041478 (detecting the pattern for positioning optically through the transparent nozzle) is applied. For instance, further more reducing of the diameter is demanded so that the pattern for positioning of the workpiece is not positioned inside of the suction hole of the transparent nozzle.

However it seems to be unrealistic to make the size of the suction hole smaller enabling to detect the pattern for positioning optically through the outside part of the suction hole of the transparent nozzle because forming the hole to the transparent body almost reaches to a process limitation. Specific explanation of an example of workpiece100is shown inFIG. 7. The workpiece100has bonding electrodes (bumps)102on a bonding face (under surface) facing to a substrate110, and a pattern for positioning101for alignment (inFIG. 7, a predetermined pattern is used) is provided on an upper surface of the workpiece. Alternatively, a plurality of patterns for positioning101may be provided on the upper surface. Further, a pattern for positioning111for alignment is provided on the substrate110, or preferably a plurality of marks111may be provided on the substrate110. Hereinafter the pattern for positioning of the workpiece100shall be referred to as “the first pattern for positioning” that is used as a first fiducial mark, and the pattern for positioning of the substrate110shall be referred to as “the second pattern for positioning” that is used as a second fiducial mark. As shown inFIG. 8A, in case of a comparatively large workpiece (conventional workpiece), it is possible to detect the first pattern for positioning of the workpiece optically through the outside part of the suction hole of the transparent nozzle215. But, as shown inFIG. 8B, in case of a smaller workpiece (recent workpiece), it is not possible to detect the first pattern for positioning of the workpiece optically through the outside part of the suction hole of the transparent nozzle. Because all or almost all of the patterns are positioned inside of the hole diameter of the suction hole even if the hole diameter of the transparent nozzle was reduced to the process limitation.

On the other hand, when a suction pathway211to the suction hole210of a transparent nozzle215is bent as L-shape as shown inFIG. 9A, it is not possible to detect the pattern for positioning of the workpiece100through the suction hole210, because inner surface (usually cylindrical) of the bent part212of the suction pathway211interferes with a field of view of an imaging unit250. In case of the suction pathway211is not bent as shown inFIG. 9B, it is also not possible to detect the pattern for positioning of the workpiece100through the suction hole210, because a joint220for suctioning interferes with the field of view of the imaging unit250. As mentioned above, it becomes to be difficult to detect the pattern for positioning on the upper surface of the workpiece along with downsizing of the workpiece.

SUMMARY OF THE INVENTION

The present invention has been made in view of the foregoing circumstances and problems, and an object thereof is to provide a workpiece transfer apparatus, a workpiece mounting apparatus and a workpiece mounting method those can detect a pattern for positioning of a workpiece without reducing hole diameter of a suction hole.

First embodiment of the present invention relates a workpiece transfer apparatus. The workpiece transfer apparatus comprises: a nozzle unit and an imaging unit wherein the nozzle unit comprises a tuber body, a suction hole opening at one end of the tuber body, an end face member sealing the other end of the tuber body and a suction pathway connected to a suction device, and at least part of the end face member is transparent, so that the imaging unit is able to take an image of a suctioned surface of a workpiece through the end face member and the suction hole when the workpiece is held by the suction hole.

In the workpiece transfer apparatus according to the first embodiment, the suction pathway may open at an inner side surface of the tuber body.

In the workpiece transfer apparatus according to the first embodiment, the imaging unit may be provided with a coaxial lighting.

In the workpiece transfer apparatus according to the first embodiment, the workpiece transfer apparatus further may comprise an image processor capable of identifying a reference position of the workpiece based on a first pattern for positioning included in an image taken by the imaging unit. The first pattern for positioning may be arranged on the suctioned surface of the workpiece.

Second embodiment of the present invention relates a workpiece mounting apparatus. The workpiece mounting apparatus comprises: the workpiece transfer apparatus having an image processor capable of identifying a reference position of the workpiece based on the first pattern for positioning included in the image taken by the imaging unit, a substrate support unit supporting a substrate which has a second pattern for positioning arranged at least on one side thereof, another imaging unit capable of taking an image including the second pattern for positioning of the substrate supported by the substrate support unit, and a relative positioning unit for the nozzle unit controlling the relative position of the nozzle unit. In the workpiece mounting apparatus, the image processor is able to identify a mount target position on the substrate based on the second pattern for positioning included in the image taken by the another imaging unit, and the relative positioning unit controls the nozzle unit so as to mount the workpiece on the substrate, while the reference position of the workpiece identified by the first pattern for positioning coincides with the mount target position on the substrate.

In the workpiece mounting apparatus according to the second embodiment, one imaging unit may take the images of both the first pattern for positioning and the second pattern for positioning.

Third embodiment of the present invention relates a workpiece mounting method for mounting a workpiece on a substrate wherein the workpiece is provided with a first pattern for positioning and the substrate is provided with a second pattern for positioning. The workpiece mounting method comprises: a first taking image step wherein an imaging unit takes an image of the substrate including the second pattern for positioning; identifying a mount target position of the workpiece on the substrate based on the second pattern for positioning included in the image taken by the first taking image step; a relative positioning step wherein a relative positioning unit relatively moves a nozzle unit picking up the workpiece to a position where the imaging unit capable of taking an image of the workpiece; a second taking image step wherein the imaging unit takes an image of the workpiece including the first pattern for positioning; identifying a reference position of the workpiece based on the first pattern for positioning included in the image taken by the second taking image step; a correcting step wherein the relative positioning unit corrects the relative position of the nozzle unit so that the reference position of the workpiece identified by the first pattern for positioning coincides with the mount target position; mounting the workpiece on the substrate while maintaining of coincidence between the reference position and the mount target position of the workpiece. In the workpiece mounting method, the nozzle unit comprises a tuber body, a suction hole opening at one end of the tuber body, an end face member sealing the other end of the tuber body and a suction pathway connected to a suction device, and in the second taking image step, the imaging unit is able to take an image of a suctioned surface of the workpiece through the end face member and the suction hole when the workpiece is suctioned by the suction hole.

In the workpiece mounting method according to the third embodiment, the nozzle unit may be moved from a withdraw position withdrawing from a position between the imaging unit and the substrate to the position between the imaging unit and the substrate in the relative positioning step, and the correcting step is executed when the nozzle unit is positioned directly above the mount target position on the substrate.

It is to be noted that any arbitrary combination of the above-described structural components as well as the expressions according to the present invention changed among a system and so forth are all effective as and encompassed by the present embodiments.

According to the embodiments, it is able to downsize the nozzle unit, by means of making the end member to be the transparent body which seals one opening opposite to the suction hole of the tuber body of the nozzle unit and taking images of the suctioned surface of the workpiece through the transparent body and the suction hole when the workpiece is suctioned by the suction hole. Therefore, it is able to detect the pattern for positioning of the workpiece which is difficult to recognize the pattern for positioning thereof by using prier arts.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described based on the following embodiments which do not intend to limit the scope of the present invention but exemplify the invention. All of the features and the combinations thereof described in the embodiments are not necessarily essential to the invention.

An embodiment mentioned bellow executes positioning of an electronic device such as a bare chip IC etc. (hereinafter “workpiece”) by way of taking an image of a pattern for positioning on an upper surface of the workpiece through a suction hole which suctions the workpiece.

FIG. 1is a rough side view of a workpiece mounting apparatus1according to the embodiment of the present invention. InFIG. 1, each direction of XYZ-axes that are orthogonal three axes are defined.FIG. 2is an enlarged main part cross-sectional view ofFIG. 1.FIG. 3Ais a plan view of an example indicated by arrow A in case of a suction hole52of a nozzle unit50is circular.FIG. 3Bis a plan view of another example indicated by arrow A in case of the suction hole52of the nozzle unit50is rectangular.

For example, the workpiece100as a mounting object is shown inFIG. 7, and a first patterns) for positioning101for position adjustment is(are) provided on a suctioned surface (a surface of Z+ direction) also shown inFIG. 3. There is a relation that a position of the workpiece100is identified if a position of the first pattern for positioning101is recognized. In the case ofFIGS. 3 and 7, parts of a pattern103of the workpiece100are used as the first patterns for positioning101. The workpiece100has electrodes102located on an undersurface thereof as shown inFIG. 7. But, electrodes102shown inFIG. 7are an arbitrarily matter, and not limited shown configuration. A second pattern for positioning111is provided with a substrate110on which the workpiece100is mounted as shown inFIG. 7, or a plurality of marks111may be provided with the substrate100. There is a relation that a position of the substrate110is identified if a position of the second pattern for positioning111is recognized. In ordinary case, a plurality of the second patterns for positioning111is provided with the substrate110for correcting in θ-axis direction.

The workpiece mounting apparatus1includes a nozzle unit50, an imaging unit70, a controller80and a substrate support unit90. In workpiece mounting apparatus1, a workpiece transfer apparatus consist of above mentioned members except the substrate support unit90which can support and hold the substrate. The workpiece mounting apparatus1is a configuration that executes positioning of the workpiece and mounting the workpiece on the substrate by using the transfer apparatus. The substrate support unit90includes a substrate loader and unloader and so on, and the substrate support unit90has functions of positioning and holding of the substrate110. A configuration of the substrate support unit90is well known, of which explanations are omitted. A workpiece mount surface (upper surface) is parallel to the XY-planes.

As shown inFIG. 2, the nozzle unit50includes a cylindrical body51as a tuber nozzle body, a suction hole52, a transparent body53and a suction pathway (vacuum vent)54. The cylindrical body51has a tapered shape of a bottom part thereof and of which center axis is parallel to Z-axis. The cylindrical body51can be made of an arbitrarily selected material, but not limited. The cylindrical body51may be a metal for example aluminum etc. which can be microfabricated. The suction hole52is opened at one end of the cylindrical body51(bottom end that is an end of the taper shape). The suction hole52makes the imaging unit70capable of taking an image of the first pattern for positioning101on an upper surface (suctioned surface) of the workpiece100, and the size and shape of the suction hole52fits within an outline of the upper surface of the workpiece100. A cross-section shape of the suction hole52may be a circular shape, and may be a polygonal shape for example a rectangular and so on if a hole processing is possible (referring toFIG. 3). The center axis of the cylindrical body51passes through the suction hole52. The transparent body53as an end face member sealing the other end (upper end) of the cylindrical body51is a flat plate made of a glass or quart etc. for example. The transparent body53achieves both maintaining negative-pressure of inside of the cylindrical body51and optical penetration toward to the imaging unit70. The suction pathway54opens at an inner side surface of the cylindrical body51, and the suction pathway54is connected to a suction device (negative-pressure source not shown). The suction hole52can pick up the workpiece100by means of the maintaining negative-pressure of inside of the cylindrical body51depending on the suction device.

The nozzle unit50is supported to be movable in XYZ-axes direction and rotatable about θ-axis (that accords to the center axis of the cylindrical body51). Functions of each derive axis are as follows:

X drive axis: for workpiece transfer, and for adjustment so as to match between the fiducial of the substrate and the fiducial of the workpiece in X-axis direction.

Y drive axis: for workpiece transfer, and for adjustment so as to match between the fiducial of the substrate and the fiducial of the workpiece in Y-axis direction.

Z drive axis: for pickup and mounting of the workpiece.

θ drive axis: for adjustment so as to match between the fiducial of the substrate and the fiducial of the workpiece in θ-axis direction. Further, each drive axis is connected to a drive transmission mechanism, some of the drive transmission mechanisms are not shown inFIG. 1. The X and Y drive axes may be connected to a drive transmission mechanism of coarse motion for transfer and a drive transmission mechanism of micromotion for adjustment (not shown) respectively. Above mentioned support mechanisms are common knowledge, however, they will described briefly bellow.

A relative positioning unit for nozzle unit50(nozzle unit support mechanism) includes a first support member10, X-axis rails11, a X slider13, a second support member15, Y-axis rails17, Y-axis slide guides19, a Y slider20, Z-axis rails21, Z-axis slide guides23, a Z slider25, a θ-axis drive motor31, a θ rotating shaft33and a θ-axis drive transmission member35.

The X-axis rails11extending in X-axis direction are fixed on a wall surface (parallel to the XZ-plane) of the first support member10which is fixed on a base2. The X slider13is slid along the X-axis rails11by the X drive shaft and the X drive axis driving motor (not shown). The second support member15is fixed on the X slider13. The Y-axis rails17are fixed on a wall surface (parallel to the YZ-plane) of the second support member15. The Y slider20is fixed to the Y-axis slide guides19which are slidable on the Y-axis rails17, so that the Y slider20is slid along the Y-axis rails17by the Y drive shaft and the Y drive axis driving motor (not shown). The Z-axis rails21are fixed on the Y slider20. The Z slider25is fixed to the Z-axis slide guides23which are slidable on the Z-axis rails21, so that the Z slider25is slid along the Z-axis rails21by the Z drive shaft and the Z drive axis driving motor (not shown). The θ-axis driving motor31is supported by the Z slider25. The θ rotating shaft33driven by the θ-axis driving motor31and the cylindrical body51of the nozzle unit50is rotatably supported by the Z slider25with bearings26and so on. One end of the θ-axis drive transmission member35is fixed to the θ rotating shaft33and the other end holds a side surface of the cylindrical body51of the nozzle unit50. Center axes of the θ rotating shaft33and cylindrical body51are coaxially-arranged. In above mentioned relative positioning unit (nozzle unit support mechanism), the nozzle unit50is movable in XYZ-axes direction and rotatable about θ-axis by means of controlling the driving motors. A nozzle position control section81of a controller80controls each driving motor. For example, the controller80is built into the first support member10, and the controller80is made as a cooperative system of hardware and software.

The imaging unit70is a two-dimensional camera for example, and that is supported and fixed by an imaging unit support member75which is fixed and stood on the base2. The imaging unit70includes a lens71, an imaging element72, a light73and a splitter74(half mirror). As shown inFIG. 2, the light73radiates light beam731which is reflected by the splitter74and reaches to the suctioned surface of the workpiece100. The lens71may be selected from a proper one of public knowledge that has an intended focal length and magnification ratio. A light axis of the lens71is parallel to the Z-axis, so that the light axis coincides with the center axis of the cylindrical body51of the nozzle unit50and passes through the center of the suction hole52. For instance, the imaging unit70can take an image of the workpiece100suctioned and held by the suction hole52optically through the transparent body53and the suction hole52. The imaging element72is arbitrarily selected from a CCD, CMOS or the like. The light73and the splitter74make up a coaxial lighting. For instance, a light beam731from the light73is bent in a parallel direction to the optical axis by the splitter72, so that the light beam731is radiated to the suction hole52. A reflected light beam732reflected by the suctioned surface of the workpiece passes the splitter74and reaches to the imaging element72. Further, the coaxial lighting is preferable for the lighting of the imaging unit70, but not limited to the coaxial lighting.

An image processor82in the controller80is electrically connected to the imaging unit70(a connection is not shown), and the image processor82carries out image processing of the output image of the imaging unit70. In particular, the image processor82identifies (calculates) the position of the second pattern for positioning111of the substrate110based on the taken image of the substrate110, so that the image processor82defines (calculates) a mount target position of the workpiece100(in other words, a target position of the pattern for positioning101on the workpiece100) on the substrate110based on the position of the second pattern for positioning111. The information of the mounting position (target position) contains a XY coordinate and an angle around the θ-axis. Further, the image processor82identifies (calculates) the position of the first pattern for positioning101of the workpiece100(reference position of the workpiece100) based on the taken image of the workpiece100, and derives (calculates) a position gap (that is a correction amount) between the position of the first pattern for positioning101and the mount target position. The correction amount includes a displacement in the XY directions and a rotation angle around the θ-axis.

Hereinafter, the operation of the embodiment, that is the workpiece mounting method, will be described.

FIGS. 4A-4Care explanatory views of a mounting operation of the apparatus shownFIG. 1etc. In default condition, the substrate support unit90is positioning and holding the substrate110under the imaging unit70(on the light axis of the imaging unit70) as shown inFIG. 4A, and the nozzle unit50is a withdrawing position from a range of view of the imaging unit70.

A first taking image step: the imaging unit70takes image(s) of the second pattern for positioning111on the substrate110at least two places.

A mount target position identifying step: the image processor82identifies (calculates) the position of the second pattern for positioning111based on the taken image (the first image data) of the first taking image step, so that the image processor82defines (calculates) the target position of the first pattern for positioning101on the workpiece100(in other words, the mount target position of the workpiece100on the substrate110) based on the identified position of the second pattern for positioning111.

A relative positioning step for the nozzle unit50: the nozzle unit50picks up the workpiece, and the nozzle position control section81controls each driving motor of the nozzle unit support mechanism so as to move the nozzle unit50to the position where the imaging unit70capable of taking the image of the workpiece100as shown inFIG. 4B. In other words, the position is between the substrate110and imaging unit70, and is preferably the position directly above the mount target position on the substrate110. After the relative positioning, the light axis of the imaging unit70approximately coincides with the center axis of the cylindrical body51of the nozzle unit50.

A second taking image step: the imaging unit70takes image of the first pattern for positioning110on the workpiece100at least two places. Where, the imaging unit70takes image of a suctioned surface of the workpiece100through the transparent body53and the suction hole52. Further, a difference of focal lengths between the first taking image step and the second taking image step can be adjusted by known means of automatic focus or the like.

A current workpiece position identifying step: the image processor82identifies (calculates) the current positions of the first pattern for positioning101(the reference position of the workpiece100) based on the taking image (the second image data) of the first pattern for positioning of the second taking image step, and derives (calculates) a deference between the target position of the first pattern for positioning101and the current position of the same, that is a necessary correction amount to coincide the position of the first pattern for positioning101to the target position.

A workpiece position correcting step: the nozzle position control section81controls each driving motor of the nozzle unit support mechanism, and corrects the relative position between the nozzle unit50and the substrate110(in XYθ-directions) so that the position of the first pattern for positioning101(that is the reference position of the workpiece) coincides with the target position (that is the mount target position of the workpiece100).

A workpiece mounting step: the nozzle position control section81makes nozzle unit50move downwardly in Z direction as shown inFIG. 4C, and the nozzle unit50mounts the workpiece100on the substrate110while maintaining of matching the position of the first pattern for positioning101to the target position. A mounting method of the workpiece100can be selected form known methods using an ultrasonic wave, silver paste, thermocompression bonding or the like. The workpiece mounting step is achieved with the nozzle unit50only moving downwardly in Z direction, in other wards without moving in XY direction and rotation around the θ-axis, mounting positional accuracy of the workpiece100is improved because of exclusion of moving accuracy in XYθ-axes. If the correction of θ-axis is not necessary, it may be at one place of the first pattern for positioning101to be taken in the second taking image step, and also may be at one place of the second pattern for positioning111to be taken in the first taking image step.

As a result of the embodiment of the present invention, it is able to downsize the nozzle unit50, by means of making the end member to be transparent body53which seals one opening opposite to the suction hole52of the cylindrical body51of the nozzle unit50and taking images of the suctioned surface of the workpiece100through the transparent body53and the suction hole52when the workpiece100is suctioned by the suction hole52. Therefore, it is able to detect the pattern for positioning of the workpiece which is difficult to recognize the pattern for positioning thereof by using prier arts.

It is preferable to make the configuration simple because images of the first pattern for positioning101and second pattern for positioning111are taken by the same imaging unit70.

Described above are explanations based on the embodiment. The description of the embodiment is illustrative in nature and various variations in constituting elements and processes involved are possible. Those skilled in the art would readily appreciate that such variations are also within the scope of the present invention. Examples of the variations are explained hereafter.

The second pattern for positioning111may be positioned at the under surface (a surface of Z− direction side) of the substrate110. In this case, the second imaging unit and light (not shown) are additionally provided separately with the imaging unit70(the first imaging unit) taking images of the first pattern for positioning101of the workpiece100. The second imaging unit must be used after position calibration between the imaging unit70and the second imaging unit by a known method. It is preferable to correct the position of the workpiece100when the workpiece100is positioned directly above the mount position on the substrate110, so that mounting positional accuracy of the workpiece100is improved because of exclusion of moving accuracy in XYθ-axes after the position correction. Further, an imaging unit for taking images of the second pattern for positioning111may provided separately with the imaging unit70for taking images of the first pattern for positioning101of the workpiece100even if the second pattern for positioning111is positioned the upper surface of the substrate110as same as the above mention embodiment.

A coordinate position of the second pattern for positioning111of the substrate110may be defined by a coordinate of whole surface of the substrate110or by a coordinate of each workpiece mounting part.

The nozzle unit50may move relatively for the imaging unit70and the substrate110, thus, the imaging unit70and the substrate110may move for the nozzle unit50.

The imaging unit70may be a fixed focus one, in the case the imaging unit70may be moved in Z direction for focusing by an imaging unit drive means between the first and second taking image step.

The upper side member of the nozzle unit50(transparent body53in the embodiment) is not needed to be transparent in all surface, if the imaging unit70can take images of the workpiece100optically through the upper side member and suction hole52. All of the nozzle unit50may be an integral transparent body as the same material.