Die frame apparatus and method of transferring dies therewith Number:7,102,524 from the United States Patent and Trademark Office (PTO) owispatent

Title: Die frame apparatus and method of transferring dies therewith

Abstract: A method, system, and apparatus for a die frame, and for transferring integrated circuit dies therewith, is described. A ring shaped groove is formed in a first surface of a wafer around a plurality of dies. The wafer is scribed to form a grid of grooves in the first surface of the wafer that separates the plurality of dies. A solidifiable material is applied to the first surface of the wafer to substantially fill the ring shaped groove and the grooves of the grid. The solidifiable material is caused to harden into a ring shaped hardened material in the ring shaped groove and into a grid shaped hardened material in the grooves of the grid. The wafer is thinned so that the grid shaped hardened material removably holds the plurality of dies.

Patent Number: 7,102,524 Issued on 09/05/2006 to Arneson,   et al.

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Inventors:	Arneson; Michael R. (Westminister, MD), Bandy; William R. (Gambrills, MD)
Assignee:	Symbol Technologies, Inc. (Holtsville, NY)
Appl. No.:	10/322,701
Filed:	December 19, 2002

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Current U.S. Class:	340/572.8 ; 257/447; 257/787; 29/458; 29/825; 340/572.1
Current International Class:	G08B 13/14 (20060101)
Field of Search:	340/572.1,572.7,572.8,825.54 257/668,678,777,774,228,292,447,730,787 438/460,462,464 29/428,458,564.6,709,743,825,832

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References Cited [Referenced By]

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U.S. Patent Documents

	4346514		August 1982		Makizawa et al.
	4925808		May 1990		Richardson
	5618759		April 1997		Boysel
	5725728		March 1998		Fuke et al.
	5904546		May 1999		Wood et al.
	6169319		January 2001		Malinovich et al.
	6189591		February 2001		Ariye et al.
	6215194		April 2001		Nakabayashi
	6303468		October 2001		Gidon et al.
	6322903		November 2001		Siniaguine et al.
	6534386		March 2003		Irie
	6606247		August 2003		Credelle et al.
	6608370		August 2003		Chen et al.
	6731353		May 2004		Credelle et al.
	2001/0016400		August 2001		Lee
	2003/0136503		July 2003		Green et al.
	2004/0020040		February 2004		Arneson et al.
	2004/0250949		December 2004		Arneson et al.

Other References

Copy of International Search Report for Application No. PCT/US03/23792, mailed Jan. 12, 2004 (4 pages). cited by other.

Primary Examiner: Trieu; Van T.
Attorney, Agent or Firm: Sterne, Kessler, Goldstein & Fox P.L.L.C.

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Parent Case Text

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CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/400,101, filed Aug. 2, 2002, which is herein incorporated by reference in its entirety.

The following applications of common assignee are related to the present application, have the same filing date as the present application, and are herein incorporated by reference in their entireties:

"Method and Apparatus for High Volume Assembly of Radio Frequency Identification Tags," Ser. No. 10/322,467;

"Multi-Barrel Die Transfer Apparatus and Method for Transferring Dies Therewith," Ser. No. 10/322,718; and

"System and Method of Transferring Dies Using an Adhesive Surface," Ser. No. 10/322,702.

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Claims

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What is claimed is:

1. A method for forming a die frame, comprising: (a) forming a ring shaped groove in a first surface of a wafer around a plurality of dies formed in the first surface of the wafer; (b) scribing the first surface of the wafer to form a grid of grooves in the first surface of the wafer that separates the plurality of dies, wherein the grid intersects with the ring shaped groove; (c) applying a solidifiable material to the first surface of the wafer to substantially fill the ring shaped groove and the grooves of the grid; (d) causing the solidifiable material to harden into a ring shaped hardened material in the ring shaped groove and into a grid shaped hardened material in the grooves of the grid; and (e) thinning the wafer so that the grid shaped hardened material removably holds the plurality of dies such that the grid shaped hardened material remains substantially intact as the plurality of dies are removed.

2. The method of claim 1, further comprising: (f) before step (b), applying a layer of a protective material on the first surface of the wafer.

3. The method of claim 2, further comprising: (g) after step (d), removing the protective material from the first surface of the wafer to remove at least some excess solidifiable material.

4. The method of claim 3, wherein step (g) comprises: dissolving the protective material in a solvent.

5. The method of claim 2, wherein step (f) comprises: spin coating the layer of protective material on the first surface of the wafer.

6. The method of claim 2, wherein the protective material is a photo resist material, wherein step (f) comprises: applying the photo-resist material on the first surface of the wafer.

7. The method of claim 2, wherein step (f) comprises: scribing the first surface of the wafer to a desired depth.

8. The method of claim 2, wherein the solidifiable material is a polymer, wherein step (c) comprises: applying the polymer to the first surface of the wafer to substantially fill the ring shaped groove and the grooves of the grid.

9. The method of claim 2, wherein the solidifiable material is a curable material, wherein step (d) comprises: curing the curable material.

10. A die frame formed according to the method of claim 1.

11. A method for assembling a plurality of radio frequency identification (RFID) tags, comprising: (a) positioning a die frame closely adjacent to a surface of a substrate tape that includes a plurality of substrates such that a die of a plurality of dies removably held in the die frame is closely adjacent to a corresponding substrate of the plurality of substrates of the substrate tape, wherein the die frame comprises a grid shaped hardened material that removably holds the plurality of dies; and (b) transferring the die onto the closely adjacent corresponding substrate from the die frame in a manner such that the die frame remains substantially intact.

12. The method of claim 11, further comprising: (c) incrementing the substrate tape; (d) positioning the die frame closely adjacent to the surface of the substrate tape such that another die of a plurality of dies removably held in the die frame is closely adjacent to a next corresponding substrate of the plurality of substrates of the substrate tape; and (e) transferring the another die onto the closely adjacent next corresponding substrate from the die frame.

13. The method of claim 12, further comprising: (f) repeating steps (c), (d), and (e).

14. The method of claim 12, further comprising: (f) repeating steps (c), (d), and (e) until all dies of the plurality of dies removably held in the die frame have been transferred to a corresponding substrate of the substrate tape.

15. The method of claim 11, wherein step (b) comprises: punching the die onto the closely adjacent corresponding substrate from the die frame.

16. The method of claim 11, wherein step (a) comprises: positioning the die frame, wherein the die frame includes a grid having a plurality of rectangular openings, wherein each opening of the plurality of rectangular openings removably holds a die.

17. The method of claim 11, wherein step (b) comprises: applying gas pressure to move the die onto the closely adjacent corresponding substrate from the die frame.

18. A method for transferring a plurality of dies to a destination surface, comprising: (a) forming a stack of die frames, each die frame including a grid having a plurality of rectangular openings, wherein each opening of the plurality of rectangular openings removably holds a die, wherein corresponding rectangular openings of the die frames in the stack are aligned in a column to form a plurality of columns of openings; and (b) transferring a die removably held in an opening from at least one column of the plurality of columns to the destination surface.

19. The method of claim 18, wherein step (b) comprises: (1) applying a punching member to a first column of openings of the plurality of columns of openings of the stack of die frames; and (2) punching with the punching member so that a die removably held in a rectangular opening of the first column of openings is transferred to the destination surface.

20. The method of claim 19, wherein step (b) further comprises: (3) repeating step (2) until the first column of openings is depleted of dies.

21. The method of claim 18, wherein step (b) comprises: (1) applying each punching member of a plurality of punching members to a respective column of openings of the plurality of columns of openings of the stack of die frames; and (2) punching with each punching member of the plurality of punching members so that a die removably held in a rectangular opening of the respective column of openings is transferred to the destination surface.

22. The method of claim 21, wherein step (b) further comprises: (3) repeating step (2) until the stack is substantially depleted of dies.

23. The method of claim 18, wherein step (b) comprises: (1) applying a hollow barrel to a first column of openings of the plurality of columns of openings of the stack of die frames; (2) causing dies removably held in the openings of the first column of openings to move into the hollow barrel; (3) repeating steps (1) and (2) until the hollow barrel contains a stack of dies; and (4) depositing dies from the hollow barrel onto the destination surface until the stack of dies contained by the hollow barrel is depleted.

24. The method of claim 18, wherein step (b) comprises: (1) applying in parallel each hollow barrel of a plurality of hollow barrels to a respective column of openings of the plurality of columns of openings of the stack of die frames; (2) causing dies removably held in the openings of the respective column of openings to move into each hollow barrel in parallel; (3) repeating steps (1) and (2) until each hollow barrel contains a stack of dies of a predetermined number; and (4) depositing dies from each hollow barrel onto the destination surface until the stack of dies contained by each hollow barrel is substantially depleted.

25. The method of claim 18, wherein the destination surface is an intermediate surface, wherein step (b) comprises: transferring a die removably held in an opening from at least one column of the plurality of columns to the intermediate surface.

26. The method of claim 18, wherein the destination surface is a substrate, wherein step (b) comprises: transferring a die removably held in an opening from at least one column of the plurality of columns to the substrate.

27. The method of claim 26, wherein the substrate includes a plurality of antenna substrates, wherein step (b) comprises: transferring a die removably held in an opening from at least one column of the plurality of columns onto a corresponding antenna substrate of the plurality of antenna substrates.

28. The method of claim 18, wherein each die has at least one contact pad located on a first surface of the die, wherein step (b) comprises: transferring a die removably held in an opening from at least one column of the plurality of columns to the destination surface so that the at least one contact pad is in contact with the destination surface.

29. The method of claim 18, wherein each die has at least one contact pad located on a first surface of the die, wherein step (b) comprises: transferring a die removably held in an opening from at least one column of the plurality of columns to the destination surface so that the at least one contact pad faces away from the destination surface.

30. The method of claim 18, further comprising: (c) prior to step (b), inserting the stack of die frames in a die-deposition apparatus.

31. A die frame apparatus, comprising: a grid having a plurality of rectangular openings therethrough; and a plurality of dies, wherein each opening of the plurality of rectangular openings removably holds a corresponding die of said plurality of dies, whereby the grid remains substantially intact as the plurality of dies are removed from the grid.

32. The apparatus of claim 31, further comprising: a ring attached around said grid.

33. The apparatus of claim 32, further comprising: a holding mechanism that holds said ring and allows for positioning of said grid during a transfer of said plurality of dies from said plurality of rectangular openings.

34. The apparatus of claim 33, wherein said grid is substantially planar, and wherein said grid has a thickness substantially equal to a thickness of a die of said plurality of dies.

35. The apparatus of claim 31, wherein said grid comprises a polymer.

36. The apparatus of claim 31, wherein said grid comprises at least one of an epoxy, a resin, a urethane, and a glass.

37. The apparatus of claim 31, wherein said grid is formed around said plurality of dies while said plurality of dies reside in a wafer.

38. A method for forming a die frame, comprising: (a) scribing a wafer attached to an adhesive surface such that a resulting plurality of dies are separated by a grid of grooves that extend through the wafer to the adhesive surface; (b) applying a solidifiable material to the scribed wafer to substantially fill the grooves of the grid; (c) causing the solidifiable material to harden into a grid shaped hardened material in the grooves of the grid; and (d) removing the adhesive surface so that the grid shaped hardened material removably holds the plurality of dies such that the arid shaved hardened material remains substantially intact as the plurality of dies are removed from the grid shaped hardened material.

39. The method of claim 38, further comprising: (e) prior to step (b), holding the adhesive surface with a support structure.

40. The method of claim 39, wherein step (b) comprises: substantially filling a space between an outer edge of the scribed wafer and an inner edge of the support structure with the solidifiable material.

41. The method of claim 40, wherein step (c) comprises: causing the solidifiable material in the space to harden into a ring shaped hardened material that supports the grid shaped hardened material within.

42. A method for forming a die frame, comprising: (a) applying a layer of a protective material on a first surface of a wafer; (b) forming a ring shaped groove in the first surface of the wafer around a plurality of dies formed in the first surface of the wafer; (c) scribing the first surface of the wafer to form a grid of grooves in the first surface of the wafer that separates the plurality of dies, wherein the grid intersects with the ring shaped groove; (d) applying a solidifiable material to the first surface of the wafer to substantially fill the ring shaped groove and the grooves of the grid; (e) causing the solidifiable material to harden into a ring shaped hardened material in the ring shaped groove and into a grid shaped hardened material in the grooves of the grid; (f) removing the protective material from the first surface of the wafer to remove at least some excess solidifiable material; and (g) thinning the wafer so that the grid shaped hardened material removably holds the plurality of dies.

43. The method of claim 42, wherein step (f) comprises: dissolving the protective material in a solvent.

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Description

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BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the assembly of electronic devices. More particularly, the present invention relates to the assembly of radio frequency identification (RFID) tags.

2. Related Art

Pick and place techniques are often used to assemble electronic devices. Such techniques involve a manipulator, such as a robot arm, to remove integrated circuit (IC) dies from a wafer and place them into a die carrier. The dies are subsequently mounted onto a substrate with other electronic components, such as antennas, capacitors, resistors, and inductors to form an electronic device.

Pick and place techniques involve complex robotic components and control systems that handle only one die at a time. This has a drawback of limiting throughput volume. Furthermore, pick and place techniques have limited placement accuracy, and have a minimum die size requirement.

One type of electronic device that may be assembled using pick and place techniques is an RFID "tag." An RFID tag may be affixed to an item whose presence is to be detected and/or monitored. The presence of an RFID tag, and therefore the presence of the item to which the tag is affixed, may be checked and monitored by devices known as "readers."

As market demand increases for products such as RFID tags, and as die sizes shrink, high assembly throughput rates for very small die, and low production costs are crucial in providing commercially-viable products. Accordingly, what is needed is a method and apparatus for high volume assembly of electronic devices, such as RFID tags, that overcomes these limitations.

SUMMARY OF THE INVENTION

The present invention is directed to methods, systems, and apparatuses for producing one or more electronic devices, such as RFID tags, that each include a die having one or more electrically conductive contact pads that provide electrical connections to related electronics on a substrate.

In a first aspect, a plurality of RFID tags is assembled according to the present invention. A plurality of dies are separated from a scribed wafer and attached to a transfer or support surface (commonly referred to as a "green tape" in the industry). The dies are transferred from the support surface to corresponding tag substrates either directly or via one or more intermediate surfaces.

In a first aspect, dies are transferred between surfaces using an adhesive surface mechanism and process.

In another aspect, dies are transferred between surfaces using a punching mechanism and process.

In another aspect, dies are transferred between surfaces using a multi-barrel die collet mechanism and process.

In another aspect, a die frame is formed. Furthermore, dies are transferred using the die frame.

In one aspect, dies may be transferred between surfaces in a "pads up" orientation. When dies are transferred to a substrate in a "pads up" orientation, related electronics can be printed or otherwise formed to couple contact pads of the die to related electronics of the tag substrate.

In an alternative aspect, the dies may be transferred between surfaces in a "pads down" orientation. When dies are transferred to a substrate in a "pads down" orientation, related electronics can be pre-printed or otherwise pre-deposited on the tag substrates.

In another aspect of the present invention, a system and apparatus enables the assembly of RFID tags. A die transfer module is present to transfer a plurality of dies from the support surface to the tag substrates in either a pads up or down manner

In another aspect of the present invention, an alternative system and apparatus enables the assembly of RFID tags. A wafer preparation module is present to transfer the dies from the support surface to a transfer surface. A die transfer module transfers the dies from the transfer surface to the tag substrates in either a pads up or down manner.

These and other advantages and features will become readily apparent in view of the following detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.

FIG. 1A shows a block diagram of an exemplary RFID tag, according to an embodiment of the present invention.

FIGS. 1B and 1C show detailed views of exemplary RFID tags, according to embodiments of the present invention.

FIGS. 2A and 2B show plan and side views of an exemplary die, respectively.

FIGS. 2C and 2D show portions of a substrate with a die attached thereto, according to example embodiments of the present invention.

FIG. 3 is a flowchart illustrating a continuous-roll tag assembly operation.

FIGS. 4A and 4B are plan and side views of a wafer having multiple dies affixed to a support surface, respectively.

FIG. 5 is a view of a wafer having separated dies affixed to a support surface.

FIG. 6 shows a flowchart providing steps for transferring dies from a first surface to a second surface, according to embodiments of the present invention.

FIG. 7 shows a flowchart providing steps for transferring a plurality of dies from a first surface to a second surface using an adhesive surface.

FIGS. 8-10 show views of a plurality of dies being transferred from a first surface to a second surface using an adhesive according to the process of FIG. 7.

FIG. 11 is a flowchart illustrating a "pads up" die transfer onto a tag substrate.

FIGS. 12A and 12B are plan and side views, respectively, of a plurality of dies in contact with a support surface and a transfer surface.

FIG. 13 is a view of a plurality of dies attached to a transfer surface.

FIG. 14 is a view of a "pads up" oriented die in contact with a transfer surface and a tag substrate.

FIG. 15 is a view of a "pads up" oriented die attached to a tag substrate.

FIG. 16 is a flowchart illustrating a "pads down" die transfer onto a tag substrate.

FIG. 17 is a view of a plurality of dies in contact with primary and secondary transfer surfaces.

FIG. 18 is a view of a plurality of dies attached to a secondary transfer surface.

FIG. 19 is a view of a "pads down" oriented die in contact with a transfer surface and a tag substrate.

FIG. 20 is a view of a "pads down" oriented die attached to a tag substrate.

FIG. 21 shows a flowchart providing steps for transferring a plurality of dies from a first surface to a second surface using a parallel punching process, according to embodiments of the present invention.

FIGS. 22-29 show views of a plurality of dies being transferred from a first surface to a second surface using the punching process of FIG. 21.

FIG. 30 shows a flowchart providing steps for assembling RFID tags, according to embodiments of the present invention.

FIGS. 31-36 show views of a plurality of dies being transferred from a chip carrier to a substrate using the punching process of FIG. 30.

FIGS. 37-39 show view of substrate structures that include a plurality of individual substrates.

FIGS. 40-45 show views of a plurality of dies being transferred from a chip carrier to a substrate using the punching process of FIG. 30.

FIGS. 46 and 47 show views of the formation of electrical conductors on a substrate.

FIGS. 48A and 48B show views of an example multi-barrel die transfer apparatus, according to an embodiment of the present invention.

FIG. 49 shows a flowchart providing example steps for transferring dies using a multi-barrel die transfer apparatus, according to an embodiment of the present invention.

FIG. 50 shows a cross-sectional view of a multi-barrel transfer apparatus being applied to first surface.

FIGS. 51 and 52 show cross-sectional views of a multi-barrel transfer apparatus transferring dies to second surfaces.

FIG. 53 shows a cross-sectional top view of an example barrel with die inside, according to an embodiment of the present invention.

FIG. 54 is a flowchart illustrating a post processing operation.

FIGS. 55 and 56 are block diagrams of tag assembly devices.

FIGS. 57A and 57B show flowcharts providing steps for making a die frame, according to example embodiments of the present invention.

FIGS. 58-62 show example views of a wafer at different process steps while being formed into a die frame, according to embodiments of the present invention.

FIG. 63 shows a cross-sectional view of an example die frame, according to an embodiment of the present invention.

FIGS. 64A-64C show views of a scribed wafer attached to an adhesive surface, and held in a wafer frame.

FIGS. 65A and 65B show the scribed wafer of FIGS. 64A-64C with a solidifiable material applied thereto, according to example embodiments of the present invention.

FIG. 66 shows a flowchart providing example steps for transferring dies using a die frame, according to an embodiment of the present invention.

FIG. 67 shows a block diagram of dies being transferred from a die frame to a substrate tape, according to an example embodiment of the present invention.

FIGS. 68A and 68B show flowcharts providing example steps for transferring dies using a die frame, according to embodiments of the present invention.

FIG. 69 shows a system for transferring dies from a stack of die frames to a substrate structure, according to an example embodiment of the present invention.

FIG. 70 shows a block diagram of dies being transferred from a stack of die frames into a multi-barrel die transfer apparatus, according to an example embodiment of the present invention.

The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the reference number.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides improved processes and systems for assembling electronic devices, including RFID tags. The present invention provides improvements over current processes. Conventional techniques include vision-based systems that pick and place dies one at a time onto substrates. The present invention can transfer multiple dies simultaneously. Vision-based systems are limited as far as the size of dies that may be handled, such as being limited to dies larger than 600 microns square. The present invention is applicable to dies 100 microns square and even smaller. Furthermore, yield is poor in conventional systems, where two or more dies may be accidentally picked up at a time, causing losses of additional dies.

The present invention provides an advantage of simplicity. Conventional die transfer tape mechanisms may be used by the present invention. Furthermore, much higher fabrication rates are possible. Current techniques process 5-8 thousand units per hour. The present invention can provide improvements in these rates by a factor of N. For example, embodiments of the present invention can process dies 5 times as fast as conventional techniques, and at even faster rates. Furthermore, because the present invention allows for flip-chip die attachment techniques, wire bonds are not necessary.

Elements of the embodiments described herein may be combined in any manner. Example RFID tags are described in the section below. Assembly embodiments for RFID tags are described in the next section. Further processing processes are then described, followed by a description of tag assembly systems.

1.0 RFID Tag

The present invention is directed to techniques for producing electronic devices, such as RFID tags. For illustrative purposes, the description herein primarily relates to the production of RFID tags. However, the description is also adaptable to the production of further electronic device types, as would be understood by persons skilled in the relevant art(s) from the teachings herein.

FIG. 1A shows a block diagram of an exemplary RFID tag 100, according to an embodiment of the present invention. As shown in FIG. 1A, RFID tag 100 includes a die 104 and related electronics 106 located on a tag substrate 116. Related electronics 106 includes an antenna 114 in the present example. FIGS. 1B and 1C show detailed views of exemplary RFID tags 100, indicated as RFID tags 100a and 100b. As shown in FIGS. 1B and 1C, die 104 can be mounted onto antenna 114 of related electronics 106. As is further described elsewhere herein, die 104 may be mounted in either a pads up or pads down orientation.

RFID tag 100 may be located in an area having a large number or pool of RFID tags present. RFID tag 100 receives interrogation signals transmitted by one or more tag readers. According to interrogation protocols, RFID tag 100 responds to these signals. Each response includes information that identifies the corresponding RFID tag 100 of the potential pool of RFID tags present. Upon reception of a response, the tag reader determines the identity of the responding tag, thereby ascertaining the existence of the tag within a coverage area defined by the tag reader.

RFID tag 100 may be used in various applications, such as inventory control, airport baggage monitoring, as well as security and surveillance applications. Thus, RFID tag 100 can be affixed to items such as airline baggage, retail inventory, warehouse inventory, automobiles, compact discs (CDs), digital video disks (DVDs), video tapes, and other objects. RFID tag 100 enables location monitoring and real time tracking of such items.

In the present embodiment, die 104 is an integrated circuit that performs RFID operations, such as communicating with one or more tag readers (not shown) according to various interrogation protocols. Exemplary interrogation protocols are described in U.S. Pat. No. 6,002,344 issued Dec. 14, 1999 to Bandy et al. entitled System and Method for Electronic Inventory, and U.S. patent application Ser. No. 10/072,885, filed on Feb. 12, 2002, both of which are incorporated by reference herein in its entirety. Die 104 includes a plurality of contact pads that each provide an electrical connection with related electronics 106.

Related electronics 106 are connected to die 104 through a plurality of contact pads of IC die 104. In embodiments, related electronics 106 provide one or more capabilities, including RF reception and transmission capabilities, sensor functionality, power reception and storage functionality, as well as additional capabilities. The components of related electronics 106 can be printed onto a tag substrate 116 with materials, such as conductive inks. Examples of conductive inks include silver conductors 5000, 5021, and 5025, produced by DuPont Electronic Materials of Research Triangle Park, N.C. Other materials or means suitable for printing related electronics 106 onto tag substrate 116 include polymeric dielectric composition 5018 and carbon-based PTC resistor paste 7282, which are also produced by DuPont Electronic Materials of Research Triangle Park, N.C. Other materials or means that may be used to deposit the component material onto the substrate would be apparent to persons skilled in the relevant art(s) from the teachings herein.

As shown in FIGS. 1A-1C, tag substrate 116 has a first surface that accommodates die 104, related electronics 106, as well as further components of tag 100. Tag substrate 116 also has a second surface that is opposite the first surface. An adhesive material or backing can be included on the second surface. When present, the adhesive backing enables tag 100 to be attached to objects, such as books and consumer products. Tag substrate 116 is made from a material, such as polyester, paper, plastic, fabrics such as cloth, and/or other materials such as commercially available Tyvec.RTM..

In some implementations of tags 100, tag substrate 116 can include an indentation or "cell" (not shown in FIGS. 1A-1C) that accommodates die 104. An example of such an implementation is included in a "pads up" orientation of die 104, as is further described elsewhere herein.

FIGS. 2A and 2B show plan and side views of an example die 104. Die 104 includes four contact pads 204a-d that provide electrical connections between related electronics 106 and internal circuitry of die 104. Note that although four contact pads 204a-d are shown, any number of contact pads may be used, depending on a particular application. Contact pads 204 are made of an electrically conductive material during fabrication of the die. Contact pads 204 can be further built up if required by the assembly process, by the depostion of additional and/or other materials, such as gold and solder flux. Such post processing, or "bumping," will be known to persons skilled in the relevant arts.

FIG. 2C shows a portion of a substrate 116 with die 104 attached thereto, according to an example embodiment of the present invention. As shown in FIG. 2C, contact pads 204a-d of die 104 are coupled to respective contact areas 210a-d of substrate 116. Contact areas 210a-d provide electrical connections to related electronics 106. The arrangement of contact pads 204a-d in a rectangular shape allows for flexibility in attachment of die 104 to substrate 116, and good mechanical adherement. This arrangement allows for a range of tolerance for imperfect placement of IC die 104 on substrate 116, while still achieving acceptable electrical coupling between contact pads 204a-d and contact areas 210a-d. For example, FIG. 2D shows an imperfect placement of IC die 104 on substrate 116. However, even though IC die 104 has been improperly placed, acceptable electrical coupling is achieved between contact pads 204a-d and contact areas 210a-d.

Note that although FIGS. 2A-2D show the layout of four contact pads 204a-d collectively forming a rectangular shape, greater or lesser numbers of contact pads 204 may be used. Furthermore, contact pads 204a-d may be laid out in other shapes in embodiments of the present invention.

2.0 RFID Tag Assembly

The present invention is directed to continuous-roll assembly techniques and other techniques for assembling tags, such as RFID tag 100. Such techniques involve a continuous web (or roll) of the material of the tag antenna substrate 116 that is capable of being separated into a plurality of tags. As described herein, the manufactured one or more tags can then be post processed for individual use. For illustrative purposes, the techniques described herein are made with reference to assembly of RFID tag 100. However, these techniques can be applied to other tag implementations and other suitable devices, as would be apparent to persons skilled in the relevant art(s) from the teachings herein.

The present invention advantageously eliminates the restriction of assembling electronic devices, such as RFID tags, one at a time, allowing multiple electronic devices to be assembled in parallel. The present invention provides a continuous-roll technique that is scalable and provides much higher throughput assembly rates than conventional pick and place techniques.

FIG. 3 shows a flowchart 300 with example steps relating to continuous-roll production of RFID tags 100, according to example embodiments of the present invention. FIG. 3 shows a flowchart illustrating a process 300 for assembling tags 100. Process 300 begins with a step 302. In step 300, a wafer 400 having a plurality of dies 104 is produced. FIG. 4A illustrates a plan view of an exemplary wafer 400. As illustrated in FIG. 4A, a plurality of dies 104 are arranged in a plurality of rows 402a-n.

In a step 304, wafer 400 is applied to a support surface 404. Support surface 404 includes an adhesive material to provide adhesiveness. For example support surface 404 may be an adhesive tape that holds wafer 400 in place for subsequent processing. FIG. 4B shows an example view of wafer 400 in contact with an example support surface 404.

In a step 306, the plurality of dies 104 on wafer 400 are separated. For example, step 306 may include scribing wafer 400 according to a process, such as laser etching. FIG. 5 shows a view of wafer 400 having example separated dies 104 that are in contact with support surface 404. FIG. 5 shows a plurality of scribe lines 502a-l that indicate locations where dies 104 are separated.

In a step 308, the plurality of dies 104 are transferred from support surface 404 to tag substrate 116. In an embodiment, step 308 may allow for "pads down" transfer. Alternatively, step 308 may allow for "pads up" transfer. As used herein the terms "pads up" and "pads down" denote alternative implementations of tags 100. In particular, these terms designate the orientation of connection pads 204 in relation to tag substrate 116. In a "pads up" orientation for tag 100, die 104 is transferred to tag substrate 116 with pads 204a-204d facing away from tag substrate 116. In a "pads down" orientation for tag 100, die 104 is transferred to tag substrate 116 with pads 204a-204d facing towards, and in contact with tag substrate 116. An example of step 308 involving "pads up" transfer is described in greater detail herein with reference to FIG. 11. An example of step 308 involving "pads down" transfer is described in greater detail herein with reference to FIG. 16.

In a step 310, post processing is performed. During step 310, assembly of RFID tag(s) 100 is completed. Step 310 is described in further detail below with reference to FIG. 54.

2.1 Die Transfer Embodiments

Step 308 shown in FIG. 3, and discussed above, relates to transferring separated dies from a support surface to a tag substrate. The separated dies that are attached to the support surface (e.g., as shown in FIG. 5) can be transferred to the tag substrate by a variety of techniques. Conventionally, the transfer is accomplished using a pick and place tool. The pick and place tool uses a vacuum die collet controlled by a robotic mechanism that picks up the die from the support structure by a suction action, and holds the die securely in the die collet. The pick and place tool deposits the die into a die carrier or transfer surface. For example, a suitable transfer surface is a "punch tape" manufactured by Mulbauer, Germany. A disadvantage of the present pick and place approach is that only one die at a time may be transferred. Hence, the present pick and place approach does not scale well for very high throughput rates.

The present invention allows for the transfer of more than one die at a time from a support surface to a transfer surface. In fact, the present invention allows for the transfer of more than one die between any two surfaces, including transferring dies from a support surface to an intermediate surface, transferring dies between multiple intermediate surfaces, transferring dies between an intermediate surface and the final substrate surface, and transferring dies directly from a support surface to the final substrate surface.

FIG. 6 shows a flowchart 600 providing steps for transferring dies from a first surface to a second surface, according to embodiments of the present invention. Structural embodiments of the present invention will be apparent to persons skilled in the relevant art(s) based on the following discussion. These steps are described in detail below.

Flowchart 600 begins with step 602. In step 602, a plurality of dies attached to a support surface are received. For example, the dies are dies 104, which are shown attached to a support surface 404 in FIG. 4A. The support surface can be a "green tape" as would be known to persons skilled in the relevant art(s).

In step 604, the plurality of dies are transferred to a subsequent surface. For example, dies 104 may be transferred according to embodiments of the present invention. For example, the dies may be transferred by an adhesive tape, a punch tape, a multi-barrel transport mechanism and/or process, or a die frame, such as are further described below, and may be transferred by other mechanisms and processes, or by combinations of the mechanisms/processes described herein. In embodiments, the subsequent surface can be an intermediate surface or an actual final substrate. For example, the intermediate surface can be a transfer surface, including a "blue tape" as would be known to persons skilled in the relevant art(s). When the subsequent surface is a substrate, the subsequent surface may be a substrate structure that includes a plurality of tag substrates, or may be another substrate type.

In step 606, it is determined whether the subsequent surface is a final surface. If the subsequent surface is a substrate to which the dies are going to be permanently attached, the process of flowchart 600 is complete. Thus, as shown in FIG. 6, the process proceeds to step 310 of flowchart 300, as shown in FIG. 3. If the subsequent surface is not a final surface, then the process proceeds to step 604, where the plurality of dies are then transferred to another subsequent surface. Steps 604 and 606 may be repeated as many times as is required by the particular application.

Any of the intermediate/transfer surfaces and final substrate surfaces may or may not have cells formed therein for dies to reside therein. Various processes described below may be used to transfer multiple dies simultaneously between first and second surfaces, according to embodiments of the present invention. In any of the processes described herein, dies may be transferred in either pads-up or pads-down orientations from one surface to another.

The die transfer processes described herein include transfer using an adhesive surface, a parallel die punch process, a multi-barrel die collect process, and a die frame. Elements of the die transfer processes described herein may be combined in any way, as would be understood by persons skilled in the relevant art(s). These die transfer processes, and related example structures for performing these processes, are further described in the following subsections.

2.1.1 Die Transfer Using an Adhesive Surface

According to an embodiment of the present invention, an adhesive substance coated onto a second surface may be pressed against separated die that reside on a first surface, causing the die to attach to the adhesively coated second surface. The second surface may be moved away from the first surface, to carry the attached die away from the first surface. The die can then be transferred to subsequent intermediate/transfer surfaces, or to a final surface, such as a substrate.

FIG. 7 shows a flowchart 700 providing steps for transferring a plurality of dies from a first surface to a second surface using an adhesive surface. For illustrative purposes, flowchart 700 will be described in reference to FIGS. 8-10, although the process of flowchart 700 is not limited to the structures shown in FIGS. 8-10.

Flowchart 700 begins with step 702. In step 702, the second surface is positioned to be closely adjacent to the first surface that has a plurality of dies attached thereto. For example, as shown in FIG. 8, a plurality of dies 104 are attached to a first surface 802. A second surface 804 is positioned closely to first surface 802. In embodiments, for example, surface 802 may be a scribed wafer or support surface, or may be an intermediate surface. Furthermore, second surface 804 may be an intermediate or transfer surface, or may be a substrate surface. An example support surface is shown in FIG. 4A, as support surface 404. Second surface 804 may be a green tape or a blue tape, as they are known in the industry, for example.

In step 704, a distance between the first surface and a second surface is reduced until the plurality of dies contact the second surface and attach to the second surface due to an adhesiveness of the second surface. An example of this is shown in FIG. 9. As shown in FIG. 9, second surface 802 is in contact with plurality of dies 104. Either or both of first and second surfaces 802 and 804 may be moved to cause the contact. Note that second surface 804 may have the adhesiveness because it is an adhesive tape, or may be a surface that has an adhesive material, such as an epoxy, glue, or wax applied thereto, to cause it to be adhesive.

In step 706, the first surface and second surface are moved apart, whereby the plurality of dies remain attached to the second surface. For example, this is illustrated in FIG. 10. As shown in FIG. 10, first surface 802 and second surface 804 have been moved apart, and the plurality of dies 104 remain attached to second surface 804. The plurality of dies 104 are detached from first surface 802. The plurality of dies 104 remain attached to second surface 804 due to a greater adhesiveness of second surface 804 relative to first surface 802.

In an embodiment, flowchart 700 may include the additional step where an adhesive material is applied to the second surface so that the adhesiveness of the second surface is greater than that of the first surface.

Note that overlapping (including identical) means may be used to perform steps 704 and 706 to reduce the distance between the first and second surfaces, and to move the first and second surfaces apart, or different means may be used. For example, the means used for performing steps 704 and/or 706 may include the use of rollers, piston-type punching techniques, air jets, and/or any other suitable mechanisms described elsewhere herein or otherwise known.

Note that flowchart 700 is applicable to dies being oriented in a pads-up or pads-down orientation on either of first and second surfaces 802 and 804. For example, flowchart 700 may include the further step where the plurality of dies attached to the first surface are oriented so that at least one contact pad of each die of the plurality of dies is facing away from the first surface. Hence, when the first surface and second surface are moved apart, the plurality of dies will remain attached to the second surface in a pads-down manner. Alternatively, flowchart 700 can include the step where the plurality of dies attached to the first surface are oriented so that at least one contact pad of each die of the plurality of dies is facing towards the first surface. Hence, when the first surface and, second surface are moved apart, the plurality of dies remain attached to the second surface in a pads-up manner.

In embodiments, the process of flowchart 700 may be implemented on any portion of, or all of the separated die on the first surface. For example, this process may be accomplished in one or more iterations, using one or more strips of an adhesive coated second surface 804 that each adhere to and carry away a single column of die 104 from first surface 802. Alternatively, a sheet sized adhesive coated second surface 804 may be used to adhere to and carry away multiple columns/any size array of die 104 from first surface 802.

The following two subsections are presented herein to provide more detailed examples of die transfer using an adhesive surface, for illustrative purposes. However, the present invention is not limited to these examples.

2.1.1.1 Pads Up Transfer

As described herein with reference to FIG. 3, in step 308, dies 104 can be transferred from support surface 404 to tag substrate 116 in a "pads up" manner. When a die 104 is transferred to tag substrate 116 in this manner, it is oriented so that connecting pads 204a-d face away from tag substrate 116.

FIG. 11 is a flowchart illustrating performance of step 308 in greater detail for "pads up" transfer. This performance begins with a step 1102. In step 1102, one or more dies 104 are oriented for "pads up" transfer from support surface 404 onto tag substrate 116. Step 1102 is described in greater detail with reference to FIGS. 12A, 12B, 13, 14, and 15, which provide exemplary views of dies 104, support surface 404, a transfer surface 1202, and tag substrate 116 during various stages of a "pads up" transfer operation.

Step 1102 comprises transferring die(s) 104 onto a transfer surface. Thus, step 1102 includes steps 1120 and 1122. In step 1120, die(s) 104 are placed in contact with transfer surface 1202. A performance of this step is illustrated in FIGS. 12A and 12B, which provide views of a die 104 in contact with support surface 404 and transfer surface 1202. Transfer surface 1202 is an adhesive material, such as tape. Placing die(s) 104 in contact with transfer surface 1202 can include the step of reducing the physical separation between support surface 404 and transfer surface 1202 until die 104 contacts transfer surface 1202. This can be performed through the use of rollers, piston-type punching techniques, and/or air jets.

Step 1120 further includes the step of aligning transfer surface 1202 with one or more rows 402. For example, FIG. 12A shows transfer surface 1202 aligned with row 402a. In this example, transfer surface 1202 has a width 1204 that is selected to contact a single row 402 of dies 104. However, other widths 1202 can be employed that enable contact with multiple rows 402.

In step 1122, die(s) 104 are removed from support surface 404, thereby resulting in the transfer of die(s) 104 from support surface 404 to transfer surface 1202. FIG. 13 is a view of a plurality of dies 104 transferred to transfer surface 1202. Removal of die(s) 104 from support surface 404 can include the steps of providing a stronger adhesive on transfer surface 1202 than on support surface 404, and increasing the physical separation between support surface 404 and transfer surface 1202. Alternatively, removal of dies 104 from support surface 404 can include the steps of providing a release adhesive on support surface 404 that loses its adhesive properties upon a release action, such as exposure to thermal energy, radiation, or ultraviolet light, and creating a release action at a time when removal is desired.

After performance of 1102, a step 1104 is performed. In step 1104, an adhesive is applied to tag substrate 116. This adhesive will provide a bond between die 104 and tag substrate 116.

A step 1106 follows step 1104. In step 1106, die(s) 104 are transferred onto tag substrate 116 in a "pads up" manner. Step 1106 includes the steps of placing die(s) 104 in contact with tag substrate 116 and removing die(s) 104 from transfer surface 1202. Snapshots from a performance of step 1106 are illustrated in FIGS. 14 and 15.

FIG. 14 shows a die 104n in contact with a transfer surface 1202 and tag substrate 116. Die 104n is in contact with a cell or indentation 1402 that is formed on tag substrate 116. Indentation 1402 enables connection pads 204 to be substantially even with surface(s) on tag substrate 116 that accommodate related electronics 106. Placing die(s) 104 in contact with tag substrate 116 includes the step of reducing the physical separation between transfer surface 1202 and tag substrate 116 until die 104 contacts tag substrate 116. This can be performed through the use of rollers, piston-type punching techniques, and/or air jets. In addition, placing die(s) 104 in contact with tag substrate 116 in a "pads up" orientation includes the step of aligning die(s) 104 with corresponding indentations 1402.

Removal of die(s) 104 from transfer surface 1202 can include the steps of providing a stronger adhesive on tag substrate 116 than on transfer surface 1202, and increasing the physical separation between transfer surface 1202 and tag substrate 104. Alternatively, removal of dies 104 from support surface 404 can include the steps of providing a release adhesive on transfer surface 1202 that loses it adhesive properties upon a release action, such as exposure to thermal energy, radiation, or ultraviolet light, and creating a release action at a time when removal is desired.

FIG. 15 shows a die 104n released from transfer surface 1202 and transferred to tag/substrate 116. As illustrated in FIG. 15, pads 204 are substantially even with surfaces 1502 and 1504 of tag substrate 116, thereby enabling electrical connections to be easily formed between pads 204 and related electronics 106 printed on these surfaces.

After step 1106, a step 1108 is performed. In step 1108, related electronics 106 are printed on tag substrate 116. Step 1106 can comprise the steps of printing related electronics 106 onto tag substrate 116 through a screen printing process, an ink jet process, and/or a thermal spray process. Alternatively, step 1106 can comprise the step of removing conductive material already disposed on tag substrate 116 through an oblation process.

After step 1108, a step 1110 is performed. In step 1110, an overcoating is applied on tag substrate 116. This overcoating protects elements of tag 100, such as die 104 and related electronics 106, from mechanical forces. In addition, this overcoating provides electrical insulation. Moreover, this overcoating can provide a compression force on tag substrate 116 to further ensure proper connections between related electronics 106 and die 104. Such a compression force can be provided through the use of heat shrinkable materials.

2.1.1.2 Pads Down Transfer

As described herein with reference to FIG. 3, in step 308, dies 104 can be transferred from support surface 404 to tag substrate 116 in a "pads down" manner. When a die 104 is transferred to tag substrate 116 in this manner, it is oriented so that connecting pads 204a-d face towards tag substrate 116.

FIG. 16 is a flowchart illustrating a performance of step 308 in greater detail for "pads down" transfer. This performance begins with a step 1602. In step 1602, one or more dies 104 are oriented for pads down transfer from support surface 404 onto tag substrate 116. Step 1602 is described in greater detail with reference to FIGS. 12A, 12B, 13-15, and 17-20. These drawings provide exemplary views of dies 104, support surface 404, a transfer surface 1202, a secondary transfer surface 1702, and tag substrate 116 during various stages of a "pads down" transfer operation.

Step 1602 comprises a step 1620 of transferring die(s) 104 onto a primary transfer surface and a step 1622 of transferring die(s) 104 onto a secondary transfer surface.

In step 1620, die(s) 104 are placed in contact with transfer surface 1202 and removed from support surface 404, thereby resulting in the transfer of die(s) 104 from support surface 404 to transfer surface 1202.

FIGS. 12A and 12B provide views of a die 104 in contact with support surface 404 and transfer surface 1202. Transfer surface 1202 is an adhesive material, such as tape. Placing die(s) 104 in contact with transfer surface 1202 can include the step of reducing the physical separation between support surface 404 and transfer surface 1202 until die 104 contacts transfer surface 1202. This can be performed through the use of rollers, piston-type punching techniques, and/or air jets.

FIG. 13 is a view of a plurality of dies 104 removed from support surface 404 and transferred to transfer surface 1202. Removal of die(s) 104 from support surface 404 can include the steps of providing a stronger adhesive on transfer surface 1202 than on support surface 404, and increasing the physical separation between support surface 404 and transfer surface 1202. Alternatively, removal of dies 104 from support surface 404 can include the steps of providing a release adhesive on support surface 404 that loses it adhesive properties upon a release action, such as exposure to thermal energy, radiation, or ultraviolet light, and creating a release action at a time when removal is desired.

After step 1620, a step 1622 is performed. In step 1622, die(s) 104 are transferred from transfer surface 1202 onto secondary transfer surface 1702. In step 1622, die(s) 104 are placed in contact with secondary transfer surface 1702. FIG. 17 provides an exemplary view of such contact, where die(s) 104 are in contact with transfer surface 1202 and secondary transfer surface 1702. Placing die(s) 104 in contact with secondary transfer surface 1702 can include the step of reducing the physical separation between support surface 404 and transfer surface 1202 until die 104 contacts transfer surface 1202. This can be performed through the use of rollers, piston-type punching techniques, and/or air jets.

Next, pursuant to step 1622, die(s) 104 are removed from transfer surface 1202 to complete the transfer to secondary transfer surface 1702. FIG. 18 is a view of a die 104 that has been removed from transfer surface 1202, and is therefore transferred to secondary transfer surface 1702. As described herein, both transfer surface 1202 and secondary transfer surface 1702 are adhesive surfaces. Thus, removal of die(s) 104 from transfer surface 1202 can include the steps of providing a stronger adhesive on secondary transfer surface 1702 than on transfer surface 1202, and increasing the physical separation between transfer surface 1202 and secondary transfer surface 1702. Alternatively, removal of die(s) 104 from transfer surface 1202 can include the steps of providing a release adhesive on transfer surface 1202 that loses it adhesive properties upon a release action, such as exposure to thermal energy, radiation, or ultraviolet light, and creating a release action at a time when removal is desired.

In step 1604, related electronics 106 are printed onto tag substrate 116. Step 1604 can comprise the steps of printing related electronics 106 onto tag substrate 116 through a screen printing process, an ink jet pro