WO2014011475A1

WO2014011475A1 - Apparatus and method for in-tray and bottom inspection of semiconductor devices

Info

Publication number: WO2014011475A1
Application number: PCT/US2013/049279
Authority: WO
Inventors: Carl Truyens
Original assignee: Kla-Tencor Corporation
Priority date: 2012-07-10
Filing date: 2013-07-03
Publication date: 2014-01-16
Also published as: TW201407707A

Abstract

An apparatus and a method for in-tray and bottom inspection of electronic devices are disclosed. A tray loading station (11) is used to transport trays (5) to and from an inspection station (10). The inspection station has a first tray carrier unit a second tray carrier unit which are movable in the inspection station in a X-coordinate direction and in a Y-coordinate direction. at least a first (8), second (9) and third (13) buffer unit arranged between the back side of the tray loading station (11) and the inspection station (10) wherein the first (8) and the second (9) buffer are adapted to deliver trays (5) to the inspection station (10); and the third buffer (13) is adapted to transport the trays (5) from the inspection station (10) to the tray loading station (11).

Description

APPARATUS AND METHOD FOR IN-TRAY AND BOTTOM INSPECTION OF

SEMICONDUCTOR DEVICES

5

CROSS REFERENCE TO RELATED APPLICATIONS

[001] This patent application claims priority of US provisional patent application No.

61/669,910 filed July 10, 2012, the application is incorporated herein by reference.

10 FIELD OF THE INVENTION

[002] The present invention relates to an apparatus for in-tray and bottom inspection of electronic devices.

[003] The present invention also relates to a method for in-tray and bottom inspection of electronic devices.

15 [004] Additionally, the present invention relates to a production line for electronic

devices.

BACKGROUND OF THE INVENTION

[005] The Japanese patent application JP H03-84944 A shows a system for enhancing a throughput of semiconductor devices to be inspected. A stage for measurement is moved 20 to a test position and a test is carried out in a held state. The stage for measurement is

returned to a loading and unloading position and a next object to be inspected is loaded.

[006] Figure 1 discloses a schematic top view of a state of the art tray 5 is tray, used for moving semiconductor devices through an inspection system. During a manufacturing process electronic components are usually transported in (JEDEC) trays (a molded

25 matrix carrier). Figure. 1 is a schematic top view of an embodiment of a tray 5 as a

carrier for the semiconductor components to be inspected. The tray 5 comprises a plurality of compartments 7. Each compartment 7 is formed in an upper side of the tray 5, so that a single compartment 7 of the tray 5 receives and stores at least a single electronic device 4 to be inspected. According to the view of Fig. 1, all compartments 7 contain electronic devices 3. [007] A coordinate system is assigned to the tray 5, whereby the main plane with the compartments 7 of the tray 5 is spanned by the X- and Y-directions, and the depth of tray 5 is orientated in the Z-direction. Also during inspection the trays 5 are used. Some inspections are done "in-tray" instead of being picked up by a pick and place robot. This is done to avoid mechanical stress/tensions on the components (due to pick and place). For in-tray inspection the tray 5 usually moved under the inspection system, in particular when the inspection system is sensitive to movements and when the field of view of the inspection system is smaller than the tray.

[008] Figure 2 shows a state of the art apparatus 1 where one in X-coordinate direction X and Y coordinate direction Y movable tray carrier unit 2 loads a tray 5 from a first buffer 8 under and inspection station 10. Once the tray 5 with the electronic devices 3 is inspected the tray 5 is unloaded a second buffer 10. Then the tray carrier unit 2 has to move to the first tray carrier unit to a tray loading station 11 and load the next tray 5 from the first buffer 8 into the inspection station 10. During all unloading and loading time the inspection system 10 is idle. The tray loading station 11 has a first tray transport lane 14, a second tray transport lane 15 and a third tray transport lane 16. The first tray transport lane 14, the second tray transport lane 15 and a third tray transport lane 16 are arranged in parallel and a direction of transport T is oriented in the X-coordinate direction. The first tray transport lane 14 is arranged such that it can communicate with the first buffer 8. The third tray transport lane 16 is arranged such that it can

communicate with the second buffer 9. A tray transfer unit 12 spans across the tray loading station 11 and the first tray transport lane 14, the second tray transport lane 15 and the third tray transport lane 16. The tray transfer unit 12 can transport trays 5 across the loading station 11.

[009] Also during inspection these trays 5 are used. Some inspections are done "in- tray" instead of being picked up by a pick and place robot (not shown). This is done to avoid mechanical stress/tensions on the components (due to pick and place). For in-tray inspection the tray 5 usually moved under the inspection system of the inspection station 10, in particular when the inspection system is sensitive to movements and when the field of view of the inspection system is smaller than the tray 5. This movement is mostly done by an x-y table 17 whereon the tray 5 is loaded/mounted/fixated/clamped. During the loading and unloading the inspection system is idle. Minimizing this idle time increases the overall throughput.

SUMMARY OF THE INVENTION

[0010] It is an object of the invention to provide an apparatus which minimizes the idle time and increases the overall throughput of trays. Additionally, the apparatus allows the backside inspection without the need to carry out an out-of-tray process.

[0011] The object is achieved by an apparatus for in-tray and bottom inspection of electronic devices which comprises:

• a tray loading station defining a front side and a back side;

• an inspection station with a first tray carrier unit a second tray carrier unit movable in the inspection station in a X-coordinate direction and in a Y- coordinate direction; and

• at least a first, second and third buffer unit arranged between the back side of the tray loading station and the inspection station wherein the first and the second buffer are adapted to deliver trays to the inspection station; and the third buffer is adapted to transport the trays from the inspection station to the tray loading station.

[0012] A further object of the invention is to provide a method with reduced idle time during unload-/loading of trays and which allows the backside inspection without the need to carry out an out-of-tray process.

[0013] The object is achieved by a method for in-tray and bottom inspection of electronic devices comprises the following steps: • loading a tray carrier unit with trays with electronic devices in from a first buffer and a second buffer to an inspection station;

• carrying out a Z-scan of the tray carrier units;

• moving both tray carrier units, one after another, into a same area of the inspection station;

• inspecting the electronic devices in the tray with an the inspection system of the inspection station;

• offloading the inspected tray from the inspection station; and

• moving out the inspected tray to a third buffer arranged between the first buffer and the second buffer.

[0014] An additional object of the present invention is to provide a production production line for electronic devices with an apparatus for in-tray and bottom inspection of electronic devices, which does not decrease the overall throughput of the production line.

[0015] The object is achieved by a production line for electronic devices which comprises: a plurality of production units and at least one apparatus for in-tray and bottom inspection of electronic devices with a tray loading station and an inspection station with a first tray carrier unit a second tray carrier unit and at least a first, a second and a third buffer unit being arranged between the tray loading station and the inspection station wherein the first and the second buffer are adapted to deliver trays to the inspection station; and the third buffer is adapted to transport the trays from the inspection station to the tray loading station and wherein the at least one apparatus is arranged such that it receives electronic devices from a downstream production unit and delivers electronic devices to a downstream production unit.

[0016] The inspection station of the inventive apparatus has the first tray carrier unit and the second tray carrier unit which are movable inside the inspection station such in the X-coordinate direction and in the Y-coordinate direction. This movement allows an alignment of the first tray carrier unit and the second tray carrier unit with third buffer unit respectively. The trays are movable from the inspection station to the third buffer unit. Additionally, the first tray carrier unit the second tray carrier unit are movable such in the Z-coordinate direction.

[0017] The third buffer is arranged between the first buffer and the second buffer and is adapted to carry out tray flipping motion of the trays in order to allow a bottom inspection of electronic of semiconductor devices. The third buffer places of a second, empty tray on top of the first tray. The flipping is carried out by rotating the two trays 180° around a horizontal axis such that the electronic devices are in the second tray. After the rotation is finalized the first tray is removed from the second tray and the second tray can be used for the bottom inspection of the electronic devices. [0018] The tray loading station has a first tray transport lane, a second tray transport lane and a third tray transport lane. The first tray transport lane is aligned with the first buffer, the second tray transport lane is aligned with the third buffer and the third tray transport lane is aligned with the second buffer. The at least one inspection unit is assigned via the first buffer, the second buffer and the third buffer respectively to least one of the first tray transport lane, the second tray transport lane and the third tray transport lane, respectively.

[0019] A tray transfer unit of the tray loading station is parallel to the front side and the back side of the tray loading station. The tray transfer unit spans across and the first tray transport lane, the second tray transport lane and the third tray transport lane of the tray loading station in order to moving the trays between the first, second or third tray transport lane. Additionally, a pick and place robot is assigned to the tray loading station for picking up single or multiple electronic devices from a tray and placing single or multiple devices in another tray or changing the order of the electronic devices within a tray. [0020] The inspection station is designed such that both tray carrier units are moveable inside the inspection station one after another to a same inspection area inside the inspection station, wherein the inspection area is larger or hat at least the same size in its X-dimension and its Y-dimension as the tray carrier units. Both, the first tray carrier unit and a second tray carrier unit can move one after another (not at the same time) in the same area. The first and second tray carrier units further feature clamp and/or vacuum means to fixate trays on the tray carrier units. An inspection system of the inspection system is mounted over the inspection area. The inspection system is an optical inspection system or a 3D topography measurement system. [0021] According to the inventive method for in-tray and bottom inspection of electronic devices a tray carrier unit with trays with electronic devices is loaded one at a time from a first buffer and a second buffer to an inspection station. Tray carrier units further feature movement in vertical Z coordinate direction. This allows the method to determine the Z-profile of the electronic devices in the trays. This information goes to a central control system, which uses the information in order to adjust quickly the focus or the operating position of the inspection system in the inspection station. As mentioned above both tray carrier units are moved one after another into a same area of the inspection station. The inspection of the electronic devices in the tray is done with the inspection system of the inspection station. One the inspection is finished the offloading of the inspected tray from the inspection station is started. Finally, the inspected tray is moved to a third buffer arranged between the first buffer and the second buffer.

[0022] The first, second and third buffer units are arranged at a back side of a tray loading station. A first tray transport lane of the tray loading station moves tray carrier units to the first buffer. A second tray transport lane of the tray loading station receives tray carrier units from the third buffer. A third tray transport lane of the tray loading station moves tray carrier units to the second buffer. A tray transfer unit of the tray loading station transports tray carrier units from the first tray transport lane to second tray transport lane or tray carrier units from the second tray transport lane to third tray transport lane. A tray input buffer and a tray output buffer are arranged at a front side of the tray loading station. The first tray transport lane receives tray carrier units from the input buffer and the second tray transport lane delivers tray carrier units to the output buffer.

[0023] The inventive apparatus can be incorporated into a production line for electronic devices. The production line has a plurality of production units and at least one inventive apparatus for in-tray and bottom inspection of electronic devices with a tray loading station and an inspection station with a first tray carrier unit a second tray carrier unit. At least a first, a second and a third buffer unit being arranged between the tray loading station and the inspection station. The first and the second buffer are adapted to deliver trays to the inspection station. The third buffer is adapted to receive trays from the inspection station and to deliver trays to the tray loading station. The at least one apparatus is arranged such in the production line that it receives electronic devices from a downstream production unit and delivers electronic devices to a downstream production unit.

[0024] The at least one apparatus for in-tray and bottom inspection of electronic devices can be arranged such in the production line that the trays enter the apparatus from one side and to continue their way in the production line to the downstream production unit on the opposite side of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which

[0026] Figure 1 is a schematic top view of a state of the art tray, used for moving semiconductor devices through an inspection system;

[0027] Figure 2 is a top view of a state of the art apparatus for allowing in-tray inspection of semiconductor devices or components;

[0028] Figure 3 is a schematic top view showing a of an apparatus according to the invention which allows a reduction of idle time;

[0029] Figure 4 is a more detailed top view of the apparatus according to the invention which allows a reduction of idle time; [0030] Figure 5 is a schematic representation of a manufacturing system which incorporates the apparatus according to the invention which allows in-tray inspection; [0031] Figure 6A and 6B is a sequence showing how idle time of the inventive apparatus can be minimized for top and bottom side inspection;

[0032] Figure 7A to 7M show the flow of trays through the inventive apparatus with the single sided 3D flow mode; and [0033] Figure 8A to 8R shows the flow of trays through the inventive apparatus with the dual sided 3D flow mode.

DETAILED DESCRIPTION OF THE INVENTION

[0034] Same reference numerals refer to same elements throughout the various figures. Furthermore, only reference numerals necessary for the description of the respective figure are shown in the figures. The shown embodiments represent only examples of how the invention can be carried out. This should not be regarded as limiting the invention.

[0035] Figure 3 is a more detailed top view of the apparatus 1 according to the invention which allows a reduction of idle time. The inspection station 10 has a first tray carrier unit 6i a second tray carrier unit 6₂. The first a second in tray carrier units 6i and 6₂ are moveable in the X-coordinate direction X, the Y-coordinate direction Y and the Z- coordinate direction Z. This allows for tray 5 change over of the first or the second tray carrier unit 6i or 6₂ while the first or the second tray carrier units 6i or 6₂ loads a tray 5 under the inspection station 10. A first buffer 8 is used to transport the first tray carrier unit 6i from the first buffer 8 under the inspection station 10. A third buffer 13 is used to receive form the first tray carrier unit 6i or second tray carrier unit 6₂ trays 5 which are removed from under the inspection station 10. The inspection station 10 has a stage 17 to move the first and the second tray carrier unit 6i or 6₂ to the inspection system 30 (see Figure 4) or to the various positions for loading and/or unloading trays 5. [0036] The apparatus comprises a tray loading station 1 1 which has a first tray transport lane 14, a second tray transport lane 15 and a third tray transport lane 16. The first tray transport lane 14, the second tray transport lane 15 and a third tray transport lane 16 are arranged in parallel and a direction of transport T is oriented in the X-coordinate direction X. The tray loading station 11 is a handling module for transporting trays 5 (e.g. Jedec trays, process carriers, etc.) from a front side 18 to a back side 19 of the tray loading station 11. The tray loading station 11 further comprising a tray transfer unit 12 that can pick a tray 5 and moves the tray 5 from one tray transport lane to any of the first, second or third tray transport lanes 14, 15 or 16. To the first tray transport lane 14 a first buffer 8 is assigned at the back side 19 of the tray loading station 11. To the second tray transport lane 15 a third buffer 13 is assigned at the back side 19 of the tray loading station 11. To the third tray transport lane 16 a second buffer 9 is assigned at the back side 19 of the tray loading station 11. [0037] The third buffer 13, which is arranged between the first buffer 8 and the second buffer 9, optionally featuring a tray flipping means 32 (see Figure 4). Tray flipping means to place a second and empty tray 5 on top of the first tray 5. The first tray 5 containing the electronic devices to be inspected and by rotating the two trays 180°deg around a horizontal axis (not shown) the electronic devices will be in the second tray 5. After the rotation the first tray 5 is removed. Each of the first, second or third tray transport lane 14, 15 or 16 has a conveyor belts 20 to move trays 5 along a direction of transport T which is oriented in the X-coordinate direction X.

[0038] Once the tray 5 with the electronic devices 3 is inspected by the inspection station 10 tray 5 is unloaded the third buffer 13. Then from the third buffer 13 the tray 5 is moved the tray loading station 11. The next tray 5 can be moved from the first buffer 8 or the second buffer 9 into the inspection station 10. During all unloading and loading time the inspection system 10 is idle. The first tray transport lane 14 is arranged such that it can communicate with the first buffer 8. The third tray transport lane 16 is arranged such that it can communicate with the second buffer 9. A tray transfer unit 12 spans across the tray loading station 11 so that the first tray transport lane 14, the second tray transport lane 15 and the third tray transport lane 16 can be reached. The tray transfer unit 12 can transport trays 5 across the loading station 11.

[0039] Figure 4 is a schematic view of a general floor plan of an apparatus 1 according to the invention which allows a reduction of idle time. The tray loading station 11 optionally comprising an inspection functionality 34 above one or several tray transport lanes 14, 15, 16 tray loading station 1 1. As also shown in figure 4, the tray loading station 1 1 has a tray input buffer 22 and a tray output buffer 24 connecting to the tray carrier units 2 at the front side 18 of the tray loading station 1 1.

[0040] As shown in Figure 3, the tray loading station 1 1 comprising pick and place robots 25 to pick up single or multiple electronic devices 3 from the tray 5. At least one bottom inspection system (not shown) is placed such that the pick and place robots 25 can move electronic devices over the bottom inspection system. It is not shown in Figure 3, but the tray loading station 11 can have additional tray transport lanes beside the tray transport lane 14, 15, 16 as already shown. The additional tray transport lanes and/or buffers are used for sorting trays 5 or placing electronic devices in individual trays. The additional tray transport lanes being parallel to the other tray transport lanes 14, 15, 16.

[0041] As shown in figure 3 and figure 4 the inspection station 10 is placed toward the first, second and third buffers 8, 9 and 13 of the tray loading station 1 1. The first, second and third buffers 8, 9 and 13 are arranged at the back side 19 of the tray loading station 1 1. The inspection station 10 comprising a first tray carrier unit 6i and a second tray carrier unit 6₂, the tray carrier units which can move the trays 5 inspection station 10 horizontally along the X-coordinate direction X and Y-coordinate direction Y. The first tray carrier unit 6i can move such that it can unload trays 5 to the third buffer 13 of the loading station 11. The second tray carrier unit 6₂ can move such that it can unload trays 5 to the third buffer 13 of the loading station 11. The second tray carrier unit 6₂ can load trays 5 from the second buffer 9 of the loading station 1 1 and the first tray carrier unit 6i can load trays 5 from the first buffer 9 of the loading station 1 1. Both, the first tray carrier unit 6i and a second tray carrier unit 6₂ can move one after another (not at the same time) in a same area A. The first tray carrier unit 6i and a second tray carrier unit 6₂ further feature movement in the Z-coordinate direction. An inspection system 30 is mounted in the inspection station 10 over the area A. The inspection system 30 being an optical inspection system. The inspection system 30 can be as well a 3D topography measurement system.

[0042] Figure 5 shows a schematic representation of a production line 100 which incorporates the apparatus 1 according to the invention for in-tray inspection. Provisions are provided to avoid/minimize vibration transfer from one module 101 of the production line 100 to the next. According to a further embodiment of the invention the apparatus 1 is modified such that the production line 100 features an in-line fioorplan. This means that trays would exit the apparatus 1 another side in order to continue their way in the production line 100. There would be no need to redirect the trays. According to yet another embodiment an extension to multiple inspections in either part of the apparatus 1 is possible (i.e. not restricted to a single inspection station in left/right part of the apparatus, not restricted to specific 2D or 3D).

[0043] Figure 6A and 6B show in a handling sequence of six trays how idle time of the inventive apparatus 1 can be minimized for top and bottom side inspection of the trays. Each tray requires a cycle of 21 seconds which can be split up into the following time slots (see table I). It is clear for a person skilled in the art that time intervals disclosed are considered as a example and the individual time intervals vary for different electronic devices to be inspected and for the different inspection processes to be carried out.

Table 1:

1 Move in 63 The tray 5 with the electronic devices 3 is moved further into the inspection station 10, so that the inspection system 30 carries out the inspection of the electronic devices 3 in the tray 5.

10 Inspection 64 The inspection system 30 carries out the inspection of the electronic devices 3 in the tray 5.

3 Offload 65 The first tray 5 is offloaded from the

inspection station 10.

1 Move out 66 The tray 5 with the electronic devices 3 is moved out from the inspection station 10

Total 21 The total tray cycle time.

[0044] The squares 60 in Figure 6 A and 6B represent one second. The cycle 60] for one tray 5 requires 21 seconds and encompasses the steps of: loading 61, Z-scanning 62, moving in 63, inspecting 64, offloading 65 and moving out 66. The cycle 60₂ for tow trays 5 requires 28 seconds and encompasses the steps of: loading 61 of tray #1, Z- scanning 62 of tray #1, moving in 63 of tray #1, inspecting 64 of tray #1, offloading 65 of tray #land moving out 66 of tray #1. Three seconds prior to the end of inspecting 64 of tray #1 the loading 61 of tray #2 starts. Then the Z-scanning 62 of tray #2, moving in 63 of tray #2 and inspecting 64 of tray #2 are carried out. Three seconds prior to the end of inspecting 64 of tray #2 the loading 61 of tray #3 starts. At the time tray #1 is running the offloading 65 a flipping and inspecting procedure 67 of tray #1 is carried out. As it is evident from Figure 6A and 6B the same procedure is carried out on tray #2 to tray #6.

[0045] The sequence of the Figures 7A to 7M shows the flow of trays through the inventive apparatus 1 with the single sided 3D flow model. The sequence is explained by six trays being fed through the apparatus. In Figure 7A and 7B, the first tray IB and the second tray 2B are fed by the first transport lane 14 of the tray loading station 11.

[0046] At the time third tray 3B (see Figure 7C) is fed by the first transport lane 14 of the tray loading station 11, the first tray IB is moved to the first buffer 8. [0047] Next in Figure 7D, the fourth tray 4B is fed by the first transport lane 14, the first tray IB is moved to the inspection station 10 and the second tray 2B is moved to the second buffer 9.

[0048] Then in Figure 7E the fifth tray 5B is fed by the first transport lane 14 the first tray IB is moved under the inspection system 30 of the inspection station 10. The second tray 2B is fed into the inspection station 10, whist the inspection of the first tray IB is still running.

[0049] In Figure 7F the sixth tray 6B is fed by the first transport lane 14 the second tray 2B is moved under the inspection system 30 of the inspection station 10. The inspection of the first tray IB is finished and the first tray IB is moved to the third buffer 13. The forth tray 4B is moved to the second buffer 9. The second tray 3B is fed from the first transport lane 14 into the inspection station 10 whist the inspection of the second tray 2B, under the inspection system 30, is still running.

[0050] In Figure 7G the sixth tray 6B is fed further by the first transport lane 14 and the fifth tray 5B is moved to the first buffer 8. The second tray 2B is moved from under the inspection system 30 of the inspection station 10 to the third buffer 13 and the first tray IB is moved from the third buffer 13 to the second transport lane 15. The third tray 3B is moved under the inspection system 30. The forth tray 4B is moved from the second buffer 9 into the inspection station 10.

[0051] In Figure 7H the sixth tray 6B is fed to the second buffer 9 and the fifth tray 5B is moved from the first buffer 8 into the inspection station 10. The forth tray 4B is fed under the inspection system 30 and the inspection is still running whilst the fifth tray 5B is moved into the inspection station lO.The third tray 3B is moved from under the inspection system 30 to the third buffer 13. The first tray IB and the second tray 2B are transported by the second transport lane 15 through the tray loading station 11.

[0052] In Figure 7H the sixth tray 6B is fed from the second buffer 9 into the inspection station 10. The fifth tray 5B is moved under the inspection system 30 and the inspection of the fifth tray 5B is still running whilst the sixth tray 6B is moved into the inspection station 10. The forth tray 4B is fed form under the inspection system 30 to the third buffer 13. The first tray IB has been transported out of the tray loading station 11. The second tray 2B and the third tray 3B are transported by the second transport lane 15 through the tray loading station 11. [0053] In Figure 7J the sixth tray 6B is moved under the inspection system 30 of the inspection station 10. The fifth tray 5B is fed form under the inspection system 30 to the third buffer 13. The second tray IB has been transported out of the tray loading station 11. The third tray 2B and the forth tray 3B are transported by the second transport lane 15 through the tray loading station 11. [0054] Figures 7K to 7M show the movement of the forth tray 4B, the fifth tray 5B and the sixth tray 6B through and out of the tray loading station 11.

[0055] The sequence of the Figures 8A to 8R shows the flow of trays through the inventive apparatus 1 with the dual sided 3D flow mode. The sequence is explained by six trays being fed through the apparatus 1 [0056] The flow of the trays in Figures 8 A to 8E is identical to the already described flow of the trays in Figures 7A to 7E.

[0057] In Figure 8F the first tray IT is flipped 180° and is transported to the second buffer 9. The second tray 2B in moved in the inspection station 10 under the inspection system 30. The third tray 3B is moved from the first buffer 9 into the inspection station whilst the inspection of the second tray 2B, under the inspection system 30, is still running. The forth tray 4B and the fifth tray 5B remain on their position on the first transport lane. [0058] In Figure 8G the flipped first tray IT is transported from the second buffer 9 into the inspection station 10. The third tray 3B in moved in the inspection station 10 under the inspection system 30. The second tray 2T is flipped 180° and is transported to the first buffer 8. The forth tray 4B and the fifth tray 5B remain on their position on the first transport lane.

[0059] In Figure 8H the flipped second tray 2T is transported from the first buffer 8 into the inspection station 10. The flipped first tray IT is moved in the inspection station 10 under the inspection system 30. The third tray 3T, removed from the inspection station 10, is flipped 180° and is transported to the second buffer 9. The forth tray 4B is moved first buffer 8. The fifth tray 5B is transported further by the first transport lane 14 and the sixth tray 6B is moved onto the tray loading station 11.

[0060] In Figure 81 the flipped third tray 3T is transported from the second buffer 9 into the inspection station 10. The flipped second tray 2T is moved in the inspection station 10 under the inspection system 30. The first flipped tray IT is moved from the inspection station 10 to the third buffer 13. The fifth tray 5B is moved to the second buffer 9. The forth tray 4B remains in first buffer 8 and sixth tray 6B is transported further by the first transport lane 14 of the tray loading station 11.

[0061] In Figure 8 J the forth tray 4B is transported from the first buffer 8 into the inspection station 10. The flipped third tray 3T is moved in the inspection station 10 under the inspection system 30. The second flipped tray 2T is moved from the inspection station 10 to the third buffer 13 and the first flipped tray IT is moved further away from the inspection station 10 by the second transport lane 15 of the tray loading station 11. The fifth tray 5B remains in second buffer 9 and the sixth tray 6B is transported by the first transport lane 14 to the first buffer 8. [0062] In Figure 8K the fifth tray 5B is transported from the second buffer 9 into the inspection station 10. The forth tray 4B is moved in the inspection station 10 under the inspection system 30. The third flipped tray 3T is moved from the inspection station 10 to the third buffer 13 whilst the first flipped tray IT and the second flipped tray 2T are moved further away from the inspection station 10 by the second fransport lane 15 of the fray loading station 11. The sixth tray 6B remains in first buffer 8.

[0063] In Figure 8L the sixth tray 6B is transported from the first buffer 9 into the inspection station 10. The fifth tray 5B is moved in the inspection station 10 under the inspection system 30. The forth flipped fray 4T is moved from the inspection station 10 to the third buffer 13 and the flipped third fray 3T and second fray 2T are moved further away from the inspection station 10 by the second transport lane 15. The flipped first fray IT has left the fray loading station 11.

[0064] In Figure 8M the sixth tray 6B is moved in the inspection station 10 under the inspection system 30 and the forth flipped fray 4T is moved from the second buffer 9 into the inspection station 10. The fifth tray 5T, removed from the inspection station 10, is flipped 180° and is transported to the first buffer 8. The flipped third tray 3T is moved further away from the inspection station 10 by the second fransport lane 15 and flipped second fray 2T has left the tray loading station 11. [0065] In Figure 8N the flipped forth tray 4T is moved in the inspection station 10 under the inspection system 30 and the flipped fifth tray 5T is moved from the first buffer 9 into the inspection station 10. The sixth tray 6T, removed from the inspection station 10, is flipped 180° and is transported to the second buffer 9. The flipped third tray 3T remains in the position on the second fransport lane 14. [0066] In Figure 80 the flipped sixth tray 6T is moved in the inspection station 10 under the inspection system 30 and the flipped fifth and inspected fray 5T is moved inspection system 30 to the third buffer 13. The flipped third tray 3T remains in the position on the second fransport lane and the flipped forth tray IT is transported further by the second fransport lane 14. [0067] The Figures 8P to 8R show the removal of the flipped sixth and inspected fray 6T from inspection system 30 to the third buffer 13 and the final fransport of the flipped forth tray 4T, the flipped fifth tray 5T and the flipped sixth tray 6T by the second fransport lane 14 out of the fray loading station 11. [0068] The invention has been described with reference to specific embodiments. It is obvious to a person skilled in the art, however, that alterations and modifications can be made without leaving the scope of the subsequent claims.

Claims

WHAT IS CLAIMED IS:

An apparatus for in-tray and bottom inspection of electronic devices which comprises:

• a tray loading station defining a front side and a back side;

The apparatus of claim 1, wherein the first tray carrier unit the second tray carrier unit are movable such in the X-coordinate direction and in the Y-coordinate direction so that the first tray carrier unit the second tray carrier unit is aligned with third buffer unit respectively and the trays are movable to the third buffer unit.

The apparatus of claim 1, wherein the first tray carrier unit the second tray carrier unit are movable such in the Z-coordinate direction.

The apparatus of claim 1, wherein the third buffer is adapted to carry out tray flipping motion of the trays in order to allow a bottom inspection of electronic devices.

The apparatus of claim 1, wherein the third buffer is arranged between the first buffer and the second buffer.

6. The apparatus of claim 1 , wherein the tray loading station has a first tray transport lane, a second tray transport lane and a third tray transport lane and the first tray transport lane is aligned with the first buffer, the second tray transport lane is aligned with the third buffer and the third tray transport lane is aligned with the second buffer.

7. The apparatus of claim 6, wherein the at least one inspection unit is assigned via the first buffer, the second buffer and the third buffer respectively to least one of the first tray transport lane, the second tray transport lane and the third tray transport lane, respectively. 8. The apparatus of claim 1 , wherein a tray input buffer is aligned at the front side of the tray loading station with the first tray transport lane and a tray output buffer is aligned at the front side of the tray loading station with the second tray transport lane.

9. The apparatus of claim 1 , wherein a tray transfer unit is parallel to the front side and the back side of the tray loading station and spans across and the first tray transport lane, the second tray transport lane and the third tray transport lane of the tray loading station for moving the trays between the first, second or third tray transport lane.

10. The apparatus of claim 1 , wherein a pick and place robot is assigned to the tray loading station for picking up single or multiple electronic devices from a tray and placing single or multiple devices in a tray.

11. The apparatus of claim 1 , wherein both tray carrier units are moveable inside the inspection station one after another to a same inspection area inside the inspection station, wherein the inspection area is larger the than the tray carrier units.

12. The apparatus of claim 11, wherein an inspection system is mounted over the inspection area. The apparatus of claim 12, wherein the inspection system is an optical inspection system or a 3D topography measurement system.

A method for in-tray and bottom inspection of electronic devices comprises the following steps:

loading a tray carrier unit with trays with electronic devices in from a first buffer and a second buffer to an inspection station;

carrying out a Z-scan of the tray carrier units;

moving both tray carrier units, one after another, into a same area of the inspection station;

inspecting the electronic devices in the tray with an the inspection system of the inspection station;

offloading the inspected tray from the inspection station; and

moving out the inspected tray to a third buffer arranged between the first buffer and the second buffer.

The method of claim 14, wherein the first, second and third buffer unit are arranged at a back side of a tray loading station and a first tray transport lane of the tray loading station moves tray carrier units to the first buffer, a second tray transport lane of the tray loading station receives tray carrier units from the third buffer and a third tray transport lane of the tray loading station moves tray carrier units to the second buffer.

The method of claim 15, wherein a tray transfer unit of the tray loading station transports tray carrier units from the first tray transport lane to second tray transport lane or tray carrier units from the second tray transport lane to third tray transport lane.

The method of claim 15, wherein a tray input buffer and a tray output buffer are arranged at a front side of the tray loading station and the first tray transport lane receives tray carrier units from the input buffer and the second tray transport lane delivers tray carrier units to the output buffer. The method of claim 14, wherein with the third buffer a placing of a second tray on top of the first tray is carried out, wherein the first tray contains the electronic devices to be inspected, then rotating the two trays 180° around a horizontal axis such that the electronic devices are in the second tray and removing the first tray from the second tray.

The method of claim 14, wherein with tray carrier units are adapted to clamp and/or vacuum to fixate the trays.

The method of claim 14, wherein each tray requires an identical cycle time from the loading of a tray carrier unit from a first buffer or a second buffer to the inspection station to the moving out of the inspected tray carrier unit to a third buffer arranged between the first buffer and the second buffer.

The method of claim 20, wherein the loading of a subsequent tray carrier unit into the inspection station starts prior to the end of the inspecting of the electronic devices of a previous tray carrier unit.

A production line for electronic devices, comprises: a plurality of production units and at least one apparatus for in-tray and bottom inspection of electronic devices with a tray loading station and an inspection station with a first tray carrier unit a second tray carrier unit and at least a first, a second and a third buffer unit being arranged between the tray loading station and the inspection station wherein the first and the second buffer are adapted to deliver trays to the inspection station; and the third buffer is adapted to transport the trays from the inspection station to the tray loading station and wherein the at least one apparatus is arranged such that it receives electronic devices from a downstream production unit and delivers electronic devices to a downstream production unit.

Production line as claimed in claim 22, wherein the at least one apparatus for in- tray and bottom inspection of electronic devices is arranged such that the trays enter the apparatus from one side and to continue their way in the production line to the downstream production unit on the opposite side of the apparatus.

24. An apparatus for in-tray and bottom inspection of electronic devices comprises:

• a tray loading station defining a front side and a back side;

• an inspection station with a first tray carrier unit a second tray carrier unit movable in the inspection station in a X-coordinate direction and in a Y- coordinate direction;

• at least a first, second and third buffer unit arranged between the back side of the tray loading station and the inspection station wherein the first and the second buffer are adapted to deliver trays to the inspection station; and the third buffer is adapted to transport the trays from the inspection station to the tray loading station; and

• a tray input buffer is aligned at the front side of the tray loading station with the first tray transport lane and a tray output buffer is arrange with the inspection station to obtain as unidirectional direction of transport trough the apparatus.

25. An apparatus for in-tray and bottom inspection of electronic devices comprises:

• a tray loading station, with a first tray transport lane, a second tray transport lane and a third tray transport lane;

• at least a first, second and third buffer unit arranged between the tray loading station and the inspection station wherein the first and the second buffer are adapted to deliver trays to the inspection station; and the third buffer is arranged between the first buffer and the second buffer and adapted to transport the trays from the inspection station to the tray loading station; and

• a tray transfer arranged above the tray loading station tray for moving the trays between the first, second or third tray transport lane.

26. The apparatus of claim 25, wherein the first tray transport lane is in aligned with the first buffer, the second tray transport lane is in aligned with the third buffer and the third tray transport lane is in aligned with the second buffer.

27. The apparatus of claim 25, wherein a tray input buffer and a tray output buffer are arranged to deliver trays to the apparatus or to receive trays from the apparatus.

28. The apparatus of claim 25, wherein the first and the second tray carrier unit are moveable inside the inspection station one after another to a same inspection area inside the inspection station, wherein the inspection area is larger the than the tray carrier units.

29. The apparatus of claim 28, wherein an inspection system is mounted over the inspection area.