NET BLOCK ASSEMBLY

Field of the Invention

The present invention relates to a net block assembly of a sawing and sorting system. The system interacts with, or includes a dicing machine which saws ("dices") a substrate with many integrated circuits formed onto it to singulate integrated circuits into individual units. In particular, the invention relates to a net block assembly for positioning the singulated individual integrated circuits.

Background of Invention

A plurality of integrated circuits is formed simultaneously on a semiconductor substrate, and the substrate is then diced to form individual integrated circuits.

The prior art provides a system for positioning integrated circuits singulated from a substrate as illustrated in a front view in Figure 1. The system includes a net block assembly 10 having a surface 10a for receiving the integrated circuits which is illustrated in a top view in Figure 2. The surface 10a is a two dimensional array of alternating first elements 12 and second elements 14. Each first element 12 is adapted to receive a singulated integrated circuit and each second element 14 is projected from the surface 10a. The first elements 12 and second elements are arranged in a chequer pattern. Figure 3a shows a top view of the net block assembly integrated in a machine for transferring the integrated circuits positioned on the net block assemblies 10, having surface 10a. Figure 3b shows a double net block assembly. In the double net block assembly, the net blocks operate independently from each other and can be driven by either a lead screw or a ball screw via a servomotor or linear motor with a linear encoder. The driving mechanism for the double net block is enclosed in a protective cover to keep out dirt and debris, and to prevent the IC devices from being damaged should they drop from the net block. The protective cover also acts as a hopper to collect IC devices that are accidentally dropped, to allow ease of retrieval of the dropped IC devices. The protective cover also includes cooling units for the purpose of ventilation.

After the integrated circuits are singulated by dicing and thereafter cleaned, a lifter assembly lifts the singulated integrated circuits for positioning on the net block assembly at a first location to be transferred to a second location for displacement. The net block surface 10a has a chequer pattern of the first elements 12 and second elements 14 to provide a larger tolerance for the alignment of adjacent integrated circuits as shown in Figures 4a, 4b and 4c. For example, if all the singulated integrated circuits from a diced substrate are placed on a net block, the alignment of adjacent integrated circuits is 0.3 to 0.5mm, being equal to the margin of adjacent integrated circuits, hence requiring an extremely small tolerance. However, by using a chequer pattern, with an interstitial raised portion, the tolerance is equivalent to the full width of the integrated circuits. Consequently, the ease of manufacture of the net block surface improves considerably.

When using the net block assembly, the integrated circuits are transferred from the first location to the second location in two quantities as shown in Figure 4. After transferring the first quantity, the net block surface is rotated 180 degrees before returning to the first location to transfer the second quantity as shown in Figure 5. This is to ensure that the integrated circuits are placed adjacent to each other and not on top of each other at the second location.

In a prior art, the integrated circuits on a net block assembly are transferred from a first position to a second position by securing the net block assembly on a rotary turntable as shown in Figure 6. The turntable is actuated by a motor to move along a guide rail from a first location to a second location.

In another prior art, the integrated circuits are transferred onto two net block assemblies, each secured on separate rotary turntables as shown in Figure 7. Both turntables are actuated by one driving motor to move between a first and a second location on an independent set of guide rails. Each set of guide rails is of a different height, such that the position of one turntable is higher than the other so that both net block assemblies will not crash into each other. At each position before the loading or unloading of the lower net block assembly, the upper turntable is not in a level position. The lower

turntable will then be elevated to the height of the upper turntable. After the loading or unloading, the lower turntable will be lowered to the original height for transfer before the upper turntable can be moved to the position. This minimises the footprint of the assembly. However the efficiency of the transfer system is compromised since only one net block assembly can be unloaded or loaded at any one time.

With the continuous need for cost reduction, manufacturers design to maximize the number of integrated circuits formed on each substrate. In a maximized design, there is a likelihood of cases where odd numbers of integrated circuits are formed. For odd numbers of integrated circuits formed, the net block surface will be incapable of transferring all the integrated circuits due to its design limitation.

An example of the problem of transferring odd number of integrated circuits is illustrated in Figures 8a and 8b. Figure 8a shows the positioning for a first odd quantity of integrated circuits, and Figure 8b shows the positioning when the net block surface is rotated to 180 degrees. The center panel remains the same. In using the net block assembly of the prior art as shown in Figure 5, the positioning for the center panel at the second location will be in error.

Summary of the invention

The present invention aims to provide an improved net block assembly for positioning singulated integrated circuits wherein the total number of integrated circuits singulated from a substrate is an odd number.

In a first embodiment, the invention provides a net block assembly in a system for positioning singulated integrated circuits, having a net block surface partially covered by a two dimensional array of first and second elements, each first element having an aperture provided with vacuum adapted to receive an integrated circuit and each second element projecting from the surface including a plurality of rows of first and second element arranged in a chequer pattern, wherein the number of elements in each row is

an odd number; and a buffer row in the array having two first elements arranged adjacent to each other wherein the number of elements in the buffer row is an odd number.

In a second embodiment, the invention provides a net block assembly in a system for positioning singulated integrated circuits with a net block surface having apertures provided with vacuum adapted to receive the integrated circuits for transferring from a first location to a second location including a first plate having a first pattern of guiding means, and a second plate having a second pattern of guiding means wherein the first and second patterns of guiding means in combination allow that the singulated integrated circuits to be positioned singly at the second location.

In a third embodiment, the invention provides a net block assembly in the second embodiment further including an actuating means for actuating the first and second plates.

In a fourth embodiment, the invention provides a net block assembly in the second embodiment further including a first actuating means for actuating the first plate, and a second actuating means for actuating the second plate.

In a fifth embodiment, the invention provides a method of transferring a plurality of singulated integrated circuits from a first location to a second location for positioning, using a net block assembly having a net block surface with apertures provided with vacuum for receiving the integrated circuits at the first location. The method includes the steps of actuating a first plate having a first pattern of guiding means to extend through the guiding means from the apertures in the net block surface for receiving the integrated circuits within the guiding means in the first plate, actuating the first plate to retract the guiding means, actuating a second plate having a second pattern of guiding means to extend through the guiding means from the apertures in the net block surface for receiving the integrated circuits within the guiding means in the second plate, wherein guiding the singulated integrated circuits for positioning at the second location by the combination of the first and second patterns of guiding means.

In a sixth embodiment, the invention provides a method of transferring a plurality of singulated integrated circuits from a first location to a second location by using a net block assembly having a net block surface for receiving the integrated circuits, partially covered by a two dimensional array of an even number of first and second elements arranged in a chequer pattern, each first element having an aperture provided with vacuum adapted to receive an integrated circuit at the first location and each second element projecting from the surface. The method includes the steps of positioning a lifter assembly for depositing a first quantity of the singulated integrated circuits in an odd number of adjacent rows for a first transfer from the first location to the second location; moving the net block assembly to the second location; displacing the first quantity of the singulated integrated circuits at the second location; moving the net block assembly back to the first location; shifting the position of the lifter assembly by a row pitch for depositing a second quantity of the singulated integrated circuits for a second transfer from the first location to the second location; moving the net block assembly to the second location; and displacing the second quantity of the singulated integrated circuits at the second.

Brief Description of the figures

Figure 1 shows a net block assembly;

Figure 2 shows a top view of a net block surface in the net block assembly;

Figure 3a shows a machine having a double net block assembly;

Figure 3b shows a double net block assembly;

Figure 4a shows the integrated circuits on a substrate;

Figure 4b shows the singulated integrated circuits placed adjacent to one another;

Figure 4c shows the singulated integrated circuits placed in a chequer pattern;

Figure 5 shows the transfer of all the singulated integrated circuits in two quantities;

Figure 6 shows a prior art having a net block assembly on a rotary turntable;

Figure 7 shows a prior art having two net block assemblies each on a separate rotary turntable which are positioned at different heights on the same footprint;

Figures 8a and 8b show the transfer of odd number of singulated integrated circuits;

Figures 9a and 9b show a first embodiment of the invention;

Figures 10a and 10b show an example of the first embodiment of the invention;

Figures 11a and 11b show a second embodiment of the invention;

Figures 12a and 12b show a second position of the second embodiment of the invention;

Figure 13 shows a net block surface of the sixth embodiment of the invention.

Detailed Description of the embodiments

Figures 9a and 9b shows a first embodiment of the invention, which is a net block assembly adapted for use in a system for positioning singulated integrated circuits. The net block assembly has a net block surface partially covered by a two dimensional array of first elements 12 and second elements 14, each first element 12 having an aperture provided with vacuum, adapted to receive an integrated circuit and each second element 14 projecting from the surface having a plurality of rows of first elements 12 and second elements 14 arranged in a chequer pattern, wherein the number of first and second elements 12, 14 in each row is an odd number; and a buffer row in the array having two

first elements 12 arranged adjacent to each other, wherein the total number of first and second elements 12,14 in the buffer row is an odd number.

Figure 9a shows an example of a positioning a first quantity of the integrated circuits for transferring from a first location to a second location. In this example, there are three elements in each row. In a buffer row 16, two of the elements are first elements and a third one is a second element. The two first elements 12a, 12b are positioned adjacent to each other, such that the center first element 12b is in between a side first element 12a and a side second element 14. After displacing the integrated circuits at the second location, the net block surface is rotated 180 degrees as shown in Figure 9b. In this rotated position, the vacuum control for the aperture in the center first element 12b is deactivated when the second quantity of the integrated circuits are positioned on the net block surface. Since the vacuum control for the aperture for the center first element 12b is deactivated, there will not be a double positioning of integrated circuits due to the buffer row at the second location. Hence, the positioning of all the integrated circuits at the second location will be complete regardless of the quantity of the integrated circuits in the substrate. There is no need to change the configuration of the net block surface for a manufacturing plant having either an odd or even number of integrated circuits formed on a substrate.

Preferably, the number of buffer rows and / or the number of rows having adjacent first elements are minimised to minimise the difficulty of manufacturing the net block surface.

Another example is shown in Figures 10a and 10b. Figure 10a shows an example of a positioning of a first quantity of the integrated circuits for transferring from a first location to a second location. In this example, there is a buffer row 16 having only first elements

12a, 12b and 12c. After displacing the integrated circuits at the second location, the net block surface is rotated 180 degrees as shown in Figure 10b. Next, the control vacuum supply to the apertures of the first elements 12a, 12b and 12c are deactivated when the second quantity of the integrated circuits are positioned on the net block surface. Similar to the example shown in Figures 9a and 9b, the positioning of all the integrated circuits

at the second location will be complete regardless of the quantity of the integrated circuits on the substrate.

In a second embodiment as shown in Figures 11a and 11b, the invention provides a net block assembly in a system for positioning singulated integrated circuits 7a, having a net block surface with apertures provided with vacuum adapted to receive the integrated circuits for transferring from a first location to a second location including a first plate 20 having a first pattern of guiding means 22, and a second plate 24 having a second pattern of guiding means 26 wherein the first and second patterns of guiding means 22, 26 in combination allows the singulated integrated circuits to be positioned singly at the second location.

Figure 11a shows a top view of the net block surface in the second embodiment and Figure 11b shows a cross-sectional view of the net block surface along the line A-A in Figure 11a. The net block surface only has first elements of apertures provided with vacuum. The first plate 20 extends the guiding means 22 through the net block surface. When the guiding means 22 are extended, the pattern of the guiding means 22 guides a first quantity of the integrated circuits to be positioned on the net block surface in an alternating pattern as illustrated in Figure 11a and held in place by the respective apertures provided with vacuum.

After the first quantity of integrated circuits is displaced at the second location, the first plate 20 is actuated to retract the guiding means 22. The second plate 24 is actuated to extend through the guiding means 26 from the net block surface. When the guiding means 26 are extended, the pattern of the guiding means 26 guides a second quantity of the integrated circuits to be positioned on the net block surface in an alternating pattern as illustrated in Figures 12a and 12b. Figure 12a is a top view of the net block surface and Figure 12b is the cross-sectional view of Figure 12a along A-A. Comparing Figures 11a and 12a, the alternating pattern is not repeated in any aperture.

The pattern of the guiding means 22, 26 can be of any configuration so long as the integrated circuits are placed singly, that is, there is no double positioning of the

singulated integrated circuits at the second position. In addition, the first guiding means 22 can overlap partially into the area for the second quantity of integrated circuits and vice versa for the second guiding means 26. Therefore, this embodiment is advantageous by allowing the guiding means 22, 26 to have larger dimensions and hence having a sturdier construction. This eases the fabrication of the guiding means 22, 26.

Further, this embodiment does not require the net block to be rotated, after transferring the first quantity of integrated circuits at the second location, prior to transferring the second quantity of integrated circuits.

In a third embodiment, the invention provides a net block assembly of the second embodiment further including an actuating means for actuating the first and second plates.

In a fourth embodiment, the invention provides a net block assembly of the second embodiment further including a first actuating means for actuating the first plate, and a second actuating means for actuating the second plate. Providing an actuating means for each plate improves the efficiency of the system so both operations of retracting the guiding means and extending the other guiding means can be done simultaneously.

The actuating means in the third or fourth embodiment can be electrically, pneumatically or hydraulically driven.

Preferably, in a system which transfers singulated integrated circuits from a first position to a second position using net block assemblies, two net block assemblies of any of the above embodiments described above are used. This increases the throughput of the system. Each net block assembly is set up and programmed to operate independently of each other without crashing into each other. Such a set up and programming helps to improve the cycle time of the operation. Further, the setup and programming allows the operation of only one net block assembly at a time. This is beneficial if one net block

assembly needs to be serviced and/ or maintained. Another advantage is that it allows for an opportunity to save on costs.

Still preferably, each net block assembly has two sets of net blocks with the same or different configuration. The assembly can be programmed to use the desired configuration. This reduces conversion time of the system and saves the manpower required for conversion if the machine is used for processing varying quantities or sizes of singulated integrated circuits.

In a fifth embodiment, the invention provides a method, using a net block assembly having a net block surface illustrated in Figures 11a, 11b, 12a and 12b, for transferring a plurality of singulated integrated circuits 7a from a first location to a second location for positioning, using a net block surface with apertures provided with vacuum for receiving the integrated circuits at the first location. The method includes the steps of actuating a first plate 20 having a first pattern of guiding means 22 to extend through the guiding means 22 from the apertures in the net block surface for receiving the integrated circuits 7a within the guiding means 22 in the first plate 20. Figures 11a, 11b illustrate the position of the integrated circuits 7a after these steps. The method further includes the steps of actuating the first plate 20 to retract the guiding means 22, and actuating a second plate 24 having a second pattern of guiding means 26 to extend the guiding means 26 through apertures in the net block surface for receiving the integrated circuits 7a within the guiding means 26 in the second plate 24. Figures 12a, 12b illustrate the position of the integrated circuits 7a after these steps. In this method, the configuration of the first and second patterns of the guiding means 22, 26 in combination guide the singulated integrated circuits 7a for positioning at the second location.

Figure 13 illustrates a net block surface for a sixth embodiment of the invention being a method of transferring a plurality of singulated integrated circuits from a first location to a second location by using a net block assembly having a net block surface for receiving the integrated circuits. The net block surface is partially covered by a two dimensional array of an even number of first elements 12 and second elements 14 arranged in a chequer pattern. Each first element 12 having an aperture provided with vacuum

adapted to receive an integrated circuit at the first location, and each second element 14 projecting from the surface. The method includes the steps of positioning a lifter assembly for depositing a first quantity of the singulated integrated circuits in an odd number of adjacent rows for a first transfer from the first location to the second location, then moving the net block assembly to the second location, displacing the first quantity of the singulated integrated circuits at the second location and moving the net block assembly back to the first location. The area 30 is the portion of the array used for the first transfer. Prior to positioning the second quantity of the singulated integrated circuits, the method includes the step of shifting the position of the lifter assembly by a row pitch for depositing a second quantity of the singulated integrated circuits for a second transfer from the first location to the second location, moving the net block assembly to the second location, and displacing the second quantity of the singulated integrated circuits at the second location. The area 32 is the portion of the array used for the second transfer.

This embodiment allows the net block assembly to be adaptable for use of both odd and even numbers of integrated circuits formed on a substrate. In addition, the embodiment eliminates the need to rotate the net block surface after positioning the first quantity of integrated circuits and prior to positioning the second quantity of integrated circuits.