Procedure for creating a document structure

Abstract

A document structure comprises a first document layer (710), a second document layer (720), and a carrier (100) between the first document layer (710) and the second document layer (720), wherein the carrier (100) has a chip receiving area (110) and a flexible area (120) at least partially surrounding the chip receiving area (110), wherein the flexible area (120) has a chip (130) received in the chip receiving area (110), and a metal structure (160) forming an antenna on a first side of the carrier facing the first document layer (710) and / or on a second side of the carrier facing the second document layer (720), wherein the antenna (160) is electrically connected to the chip (130) by means of a contacting structure (135), the contacting structure (135) extending through the flexible area (120).wherein the flexible area (120) is free of metal at least on the first side and / or the second side, except for the contacting structure (135) and the chip receiving area 110.

Description

[0001] The invention relates to a method for producing a document structure and a document structure.

[0002] For various applications, such as (e.g.) crypto-banknotes, documents, etc., it is desirable to embed a chip in layers of paper.

[0003] The chip should be able to provide contactless communication, for example as near field communication (NFC), for example as a passive element that receives energy via near field communication, e.g. from a smartphone, and - depending on the planned use - be set up to perform application-related functions, e.g. to sign transactions (e.g. using elliptic curve cryptography, e.g. a so-called Elliptic Curve Digital Signature Algorithm (ECDSA)).

[0004] However, the chip itself is typically too small to accommodate an antenna suitable for NFC directly on the chip.

[0005] Furthermore, current chip carrier arrangements for use in paper-based documents, such as banknotes, are relatively inflexible. This lack of flexibility means they are easily damaged during the manufacturing process or during subsequent use.

[0006] Banknotes must therefore pass a so-called "crumpling test".

[0007] For example, assuming a conventional banknote with a thickness between approximately 90 µm and 110 µm, and that two layers of paper, each approximately 35 µm thick, should be present to provide the banknote functionality, between 20 µm and 40 µm remain for a layer in which the chip with the described functionality is to be placed, possibly slightly more, for example up to approximately 70 µm, if a slightly thicker banknote is acceptable.

[0008] DE 198 40 220 A1 discloses a transponder module comprising a layer made of an insulating material, which serves as the sole substrate. An antenna array is formed on a first main surface of the substrate. An unpackaged circuit chip is arranged in a recess of the substrate such that a first main surface of the circuit chip is substantially flush with the first main surface of the first substrate. Electrical connections between the circuit chip and the antenna array are provided.

[0009] DE 198 46 237 A1 discloses a method for manufacturing a microtransponder, in which an antenna metallization with a first and a second terminal end is first applied to a substrate to form a first module. A compound metallization is applied to a flexible carrier film, whereupon a circuit chip with a first and a second terminal surface is applied to the compound metallization such that at least the first terminal surface of the circuit chip is electrically connected to the compound metallization. The flexible carrier film with the circuit chip applied to it constitutes a second module.The first and second modules are subsequently connected in such a way that the connecting metallization is electrically conductively connected to the first terminal end of the antenna metallization, and that the second terminal surface of the circuit chip is electrically conductively connected to the second terminal end of the antenna metallization.

[0010] A document structure according to claim 1 and a method for creating a document structure according to claim 16 are provided. Further embodiments are described in the dependent claims.

[0011] In various embodiments, a document structure is provided with a chip that meets the described requirements regarding flexibility, thickness and robustness.

[0012] The document structure can be equipped with a substrate and a flat metal antenna (e.g., formed as a metallization layer) arranged on it, which has an antenna area of, for example, approximately 25 mm x 25 mm. The chip can be arranged within the antenna area, for example, as a so-called "chip-in-coil" (CiC) arrangement.

[0013] Exemplary embodiments of the invention are shown in the figures and are explained in more detail below.

[0014] They show Fig. 1. A carrier for use in a document structure - front view (chip side) according to various embodiments; Fig. 2 A carrier for use in a document structure - reverse side view according to various embodiments; Fig. 3A to 3B A carrier for use in a document structure with a meandering structure according to various embodiments; Fig. 4 A connection area of ​​a chip (IC) for use in a document structure according to various embodiments; Fig. 5A to 5B A carrier for use in a document structure according to various implementation examples; Fig. 6A to 6B A carrier for use in a document structure according to various implementation examples; Fig. 7A to 7B A carrier of a document structure as well as a document structure according to various implementation examples; Fig. 8A to 8E A carrier for use in a document structure wherein the flexible area has at least one recess, according to various embodiments; Fig. 9A to 9B A carrier for use in a document structure according to various implementation examples;

[0015] Within this description, the term "connected" is used to describe both direct and indirect connections. In the figures, identical or similar elements are marked with identical reference symbols where appropriate.

[0016] In various embodiments, a thin and partially flexible chip carrier structure, for example an FCOS module with a flexible (membrane) area, is provided, which can be embedded in two layers of paper to form a document structure. The embedding can be achieved, for example, through a lamination process.

[0017] When integrating, for example, an ultra-thin semiconductor chip into a flexible chip carrier structure, various embodiments utilize a combination of design features, materials and (e.g., already essentially known) processes to enable cost-effective, high-throughput manufacturing, for example, through a flip-chip assembly process.

[0018] The substrate on which the chip with the chip-receiving area is mounted has a flexible area / membrane. The substrate can be made of, for example, an elastic plastic material such as polycarbonate, polyethylene terephthalate, epoxy laminate, and / or polyimide. The flexible area, as part of the substrate, is at least partially made of the same material as the substrate. The flexible area can be made of, for example, polyimide, epoxy laminate, polycarbonate, or polyethylene terephthalate. The substrate can be made of a single material or, for example, of a stack of layers. The substrate can, for example, be a so-called flex tape, which is of a substantially known type.

[0019] Fig. Figure 1 shows a carrier for use in a document structure in a top view, comprising a carrier 100 which can be arranged between a first document layer 710 and a second document layer 720, wherein the carrier 100 has a chip receiving area 110 and a flexible area 120 at least partially surrounding the chip receiving area 110, wherein the chip receiving area 110 may have an area that is mechanically more stable than the flexible area 120. The area that is mechanically more stable than the flexible area 120 may have a metal structure.

[0020] The area that is mechanically more stable than the flexible area 120 can be a plate and / or as shown in Fig. 3A and in the magnification in the Fig. 3B shown consists of several plates and has a meandering structure 315.

[0021] The chip recording area 110 can have an area of ​​approximately 1 mm2 to 6 mm2, for example approximately 3 mm2 to 5 mm2.

[0022] The area of ​​the flexible zone 120 can essentially have a rectangular shape.

[0023] The area of ​​the flexible region 120 can be approximately 30 mm2 to approximately 50 mm2.

[0024] The flexible area 120 must be at least 80% free of metal.

[0025] The flexible area 120 can have a thickness of 6 to 50 µm.

[0026] The flexible area 120 can have a modulus of elasticity of approximately 1000-5000 N / mm2, whereby in general the size of the flexible area 120 around the chip receiving area 110 should be dimensioned so that bending moments / chip breakage during manufacturing or use can be effectively compensated / prevented.

[0027] A chip 130 is mounted in the chip mounting area 110. The chip 130 can, for example, have a thickness in the range of approximately 20 µm to approximately 40 µm. The electrically conductive connection can be made, for example, by means of a soldered connection or by means of an electrically conductive adhesive 150. For example, an anisotropic conductive adhesive (ACA) can be used.

[0028] A metal structure on the carrier 100 forms an antenna / antenna structure 160 for contactless functionality via near-field communication and optionally a capacitor structure 140. This capacitor structure 140 and antenna 160 can face the first document layer 710. Optionally, a metal structure-forming antenna 260 can also be arranged on or exclusively on the second side of the carrier 100, which can face a second document layer 720.

[0029] The antenna 160, 260 is electrically connected to the chip 130 and optionally to the capacitor structure 140, 240 by means of a contacting structure 135 (135-1 and 135-2), wherein the contacting structure 135 extends through the flexible area 120, wherein the flexible area 120 may be free of metal at least on the first side except for the contacting structure 135 and the chip receiving area 110.

[0030] As the Fig. As shown in the rear view, the second side of the flexible area 120R can be free of metal.

[0031] Optionally, a capacitor structure 240 and an antenna 260 forming a metal structure can be arranged on the second side of the support 100.

[0032] Fig. Figure 4 shows a chip (IC) 430 with a redistribution layer (RDL) 400 as its connection area. The RDL 400 has two RDL terminals, LA and LB, 410 and 420, which are isolated from each other and connected to the chip contacts LA and LB. These RDL terminals 410 and 420 serve for an electrical connection to the contact structures 135-1 and 135-2, which in turn are electrically connected to the antenna 160, 260 and, if applicable, to the capacitor structure 140, 240. The electrically conductive connection can be made, for example, by soldering (i.e., using a solder) or by gluing (i.e., using an electrically conductive adhesive).

[0033] The RDL 400 can have a thickness in the range of approximately 5 µm to approximately 40 µm, for example around 20 µm. The RDL 400 can, for example, have a layer sequence of copper-nickel-gold, or another suitable metal, or for example another layer stack.

[0034] The thickness of the RDL 400 can be chosen in a ratio to the chip thickness, which is in a range of approximately 0.1 to approximately 1, e.g. from approximately 0.3 to approximately 1.

[0035] In various embodiments, the (ultra-thin) chip 430 can have an RDL 400, which can provide mechanical reinforcement, in particular for a so-called pick-and-place process, in which the isolated chip is detached from an auxiliary carrier and positioned at the target position on the carrier 100.

[0036] The Fig. 5A and Fig. Figure 5B (cross-section BB) shows a carrier 100 with a chip 130 for use in a document structure with a straight flexible area 120. The metal structures 510 and 520 for the antenna are located outside the flexible area 120 on the first side of the carrier 100 and the back side of the carrier 100, respectively.

[0037] The Fig. 6A and Fig. Figure 6B (cross-section CC) shows a carrier 100 with a chip 130 for use in a document structure with a curved flexible area 120. The metal structure 610 for the antenna is located outside the flexible area 120 on the first side of the carrier 100.

[0038] The Fig. 6B (cross-section CC) shows the deflection of the flex membrane z in the flexible area 120. The deflected flexible area 120 allows the carrier 100 to be pressed onto the back of the chip 130 during manufacturing.

[0039] The Fig. 7A and Fig. Figure 7B (cross-section DD) shows a carrier 100 with a chip 130 in a document structure 700 with a curved flexible area 120. The area of ​​the flexible area 120 is at least partially lowered with respect to the carrier plane.

[0040] Document structure 700 comprises a first document layer 710 and a second document layer 720, with the carrier 100 positioned between the first document layer 710 and the second document layer 720. Document structure 700 can be produced, for example, by a lamination process with the following steps: • Forming a carrier 100, wherein the carrier 100 has a chip receiving area 110 and a flexible area 120 at least partially surrounding the chip receiving area 110; • Forming an antenna structure 140 on a first side of the carrier 100 facing a first document layer 710, and / or on a second side of the carrier 100 facing a second document layer 720; • Forming a contacting structure 135, whereby the antenna structure 140 is electrically connected to the chip receiving area 110, wherein the contacting structure 135 extends at least partially through the flexible area 120; • Fixing and electrically coupling a chip 130 in the chip receiving area 110 • Applying the first document layer 710 to the first side of the carrier 100 and applying the second document layer 720 to the second side of the carrier 100.

[0041] The document structure 700 can consist of several layers. For example, additional layers of paper, adhesive, and / or holograms can be incorporated, and then the entire document structure 700 can be embedded in a document, such as a banknote, passport, certificate, identification card, or other document issued by a (governmental) authority. Due to the curved, flexible area 120, the chip 130 occupies a balanced, break-resistant position within the, for example, laminated document structure 700 and is difficult to detect from the outside.

[0042] The Fig. Figures 8A to 8E show a carrier for use in a document structure 700, wherein the flexible area 120 has at least one recess 125.

[0043] The recess 125 can consist of several recesses 125 and / or have a square and / or circular shape.

[0044] The recess 125 in the flexible area 120 optimizes the mechanical decoupling of the chip receiving area 110 from the chip carrier module. The recess 125 can be produced, for example, by punching a hole in the carrier material.

[0045] Advantageous designs are described in the Fig. 8A to 8E shown.

[0046] Fig. 8A shows a continuous, straight cutout 125 around the chip receiving area 110.

[0047] Fig. Figure 8B shows several straight recesses 125 that are decoupled from each other.

[0048] Fig. 8C shows a circular, continuous cutout 125.

[0049] Fig. Figure 8D shows a diagonal arrangement of the contacting structure 135 (135-1 and 135-2) for contacting LA / LB to achieve uniform stress relief in the X and Y directions. The contacting structure 135 (135-1 and 135-2) can include additional structures for strain relief.

[0050] Fig. 8E shows a non-rectangular, straight-line recess 125 in trapezoidal shape.

[0051] The Fig. 9A and Fig. Figure 9B (enlarged section) shows a carrier 900 for use in a document structure. In this embodiment, the chip receiving area 910 is embossed into the carrier 900. The embossing creates a flexible, permanently recessed chip receiving area 910, which protects the chip (not shown) from bending stress and thus chip breakage. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 198 40 220 A1

[0008] DE 198 46 237 A1

[0009]

Claims

[1] Document structure (700), comprising: • a first set of documents (710); • a second set of documents (720); • a carrier (100) between the first document layer (710) and the second document layer (720), wherein the carrier (100) has a chip receiving area (110) and a flexible area (120) at least partially surrounding the chip receiving area (110); • a chip (130) received in the chip receiving area (110); • a metal structure (160) forming an antenna on a first side of the carrier facing the first document layer (710) and / or on a second side of the carrier facing the second document layer (720); • wherein the antenna (160) is electrically conductively connected to the chip (130) by means of a contacting structure (135), wherein the contacting structure (135) extends through the flexible region (120); • wherein the flexible region (120) is free of metal at least on the first side and / or the second side except for the contacting structure (135) and the chip receiving region 110. [2] Document structure (700) according to claim 1, wherein the carrier (100) has a region in the chip receiving region (110) which is mechanically more stable than the flexible region (120). [3] Document structure (700) according to claim 2, wherein the region which is mechanically more stable than the flexible region (120) comprises a metal structure (115). [4] Document structure (700) according to one of claims 2 to 3, wherein the region which is mechanically more stable than the flexible region (120) is a plate. [5] Document structure (700) according to one of claims 1 to 4, wherein the chip receiving area (110) has an area of ​​approximately 1 mm2 to 6 mm2, for example approximately 3 mm2 to 5 mm2. [6] The document structure (700) of any one of claims 1 to 5, wherein the surface of the flexible region (120) has a substantially quadrangular shape. [7] Document structure (700) according to one of claims 1 to 6, wherein the surface of the flexible region (120) is at least partially depressed with respect to the support plane. [8] The document structure (700) of any one of claims 1 to 7, wherein the area of ​​the flexible region (120) is approximately 30 mm2 to approximately 50 mm2. [9] The document structure (700) of any one of claims 1 to 8, wherein the surface of the flexible region (120) is made of polyimide, epoxy laminate, polycarbonate, or polyethylene terephthalate. [10] The document structure (700) of any one of claims 1 to 9, wherein the flexible region (120) is at least 80% free of metal. [11] Document structure (700) according to one of claims 1 to 10, wherein the flexible region (120) has a thickness of 6 to 50 µm. [12] Document structure (700) according to one of claims 1 to 11, wherein the flexible region (120) has a modulus of elasticity of approximately 1000-5000 N / mm 2 has. [13] Document structure (700) according to one of claims 1 to 12, wherein the flexible region (120) has at least one recess (125). [14] Document structure (700) according to claim 13, wherein the recess (125) consists of a plurality of recesses (125). [15] Document structure (700) according to one of claims 13 or 14, wherein the recess (125) has a square and / or circular shape. [16] A method for producing a document structure (700), the method comprising: • Forming a carrier (100), wherein the carrier (100) has a chip receiving area (110) and a flexible area (120) at least partially surrounding the chip receiving area (110); • forming an antenna structure (160) on a first side of the carrier (100) facing a first document layer (710) and / or on a second side of the carrier (100) facing a second document layer (720); • Forming a contacting structure (135), whereby the antenna structure (160) is electrically conductively connected to the chip receiving area (110), wherein the contacting structure (135) extends at least partially through the flexible area (120); • Fixing and electrically coupling a chip (130) in the chip receiving area (110) • Applying the first document layer (710) to the first side of the carrier (100) and applying the second document layer (720) to the second side of the carrier (100). [17] A method for producing a document structure (700) according to claim 16, the method further comprising: • Forming a region in the chip receiving region (110) that is mechanically more stable than the flexible region (120). [18] A method for producing a document structure (700) according to claim 17, the method further comprising: • Forming a plate in the chip receiving area (110) which is mechanically more stable than the flexible area (120). [19] A document comprising a document structure (700) according to any one of claims 1 to 18. [20] A document according to claim 19, wherein the document is a banknote, a passport, a certificate, an identification card or any other document issued by a government authority.

Images