# US 9,436,902 B1 · RFID integrated circuits with large contact pads

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- Number: US 9,436,902 B1
- Document ID: US9436902B1
- Status: Granted
- Kind: B1
- Application number: 14/451,416
- Filed: 2014-08-04
- Granted: 2016-09-06
- Earliest claimed: 2013-02-25
- Assignees: Impinj, International Ltd.
- Applicants: Impinj, International Ltd.
- Inventors: Ronald Lee Koepp; Tan Mau Wu; Ronald A. Oliver; Harley Heinrich; Jaideep Mavoori; Christopher J. Diorio
- Web page: https://patentgrep.com/patent/US9436902B1

## CPC

- G06K 19/07752: {using an interposer}
- G06K 19/07722: {the record carrier being multilayered, e.g. laminated sheets (flat articles in general, see B32B37/00)}
- G06K 19/07754: {the connection being galvanic}
- H01Q 1/2283: {mounted in or on the surface of a semiconductor substrate as a chip-type antenna or integrated with other components into an IC package}
- H01Q 23/00: Antennas with active circuits or circuit elements integrated within them or attached to them
- H10W 90/724: {between a chip and a stacked insulating package substrate, interposer or RDL}
- G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72)
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

An RFID IC assembly having a repassivation layer and a conductive redistribution layer may be assembled onto a tag substrate with an additional layer. The additional layer includes one or more etchants for creating an opening in a nonconductive barrier layer between the assembly and the substrate, and may also include an adhesive for attaching the assembly to the substrate.

## Claims

### Claim 1

A Radio Frequency Identification (RFID) tag precursor comprising:
an assembly including an RFID integrated circuit (IC), a nonconductive repassivation layer on a surface of the IC and confined within a perimeter of the surface, and a conductive redistribution layer on the repassivation layer and confined within the perimeter of the surface, in which at least a first portion of the redistribution layer is electrically connected to the IC through a first opening in the repassivation layer,
a substrate including a first antenna terminal;
a second opening, formed by an etchant, in a nonconductive barrier present on at least one of the first antenna terminal and the first portion of the redistribution layer, and
an adhesive attaching the assembly to the substrate; wherein
a first electrical connection is formed between the first antenna terminal and the first portion of the redistribution layer through the second opening; and
the first opening and the second opening are nonoverlapping.

### Claim 2 (depends on 1)

The RFID tag precursor of claim 1, in which the redistribution layer is patterned which allows portions that have a local parasitic capacitance to the IC that exceeds a predefined threshold are excised.

### Claim 3 (depends on 1)

The RFID tag precursor of claim 1, in which the nonconductive barrier is at least one of an oxide and a masking layer.

### Claim 4 (depends on 1)

The RFID tag precursor of claim 1, in which the first electrical connection includes the adhesive.

### Claim 5 (depends on 1)

The RFID tag precursor of claim 1, in which the etchant includes a textured surface on the redistribution layer that forms the second opening by breaking the nonconductive barrier.

### Claim 6 (depends on 1)

The RFID tag precursor of claim 1, in which the etchant includes conductive particles that form the second opening by breaking the nonconductive barrier.

### Claim 7 (depends on 1)

The RFID tag precursor of claim 1, in which the etchant forms the second opening by reacting with the nonconductive barrier.

### Claim 8 (depends on 1)

The RFID tag precursor of claim 1, wherein:
the substrate further includes a second antenna terminal;
the redistribution layer further includes a second portion electrically isolated from the first portion and electrically connected to the IC;
the nonconductive barrier is further present on at least one of the second antenna terminal and the second portion of the redistribution layer,
the tag precursor further includes a third opening, formed by the etchant, in the nonconductive barrier; and
a second electrical connection is formed between the second antenna terminal and the second portion of the redistribution layer through the third opening.

### Claim 9

A Radio Frequency Identification (RFID) tag precursor comprising:
an assembly including an RFID integrated circuit (IC) with an IC contact, a nonconductive repassivation layer on a surface of the IC and confined within a perimeter of the surface, and a conductive redistribution layer on the repassivation layer and confined within the perimeter of the surface;
a substrate including a first antenna terminal;
an adhesive attaching the assembly to the substrate;
a first electrical connection between a first portion of the redistribution layer and the IC contact;
an opening, formed by an etchant, in a nonconductive barrier present on at least one of the first antenna terminal and the first portion of the redistribution layer; and
a second electrical connection formed between the first antenna terminal and the first portion of the redistribution layer through the opening.

### Claim 10 (depends on 9)

The RFID tag precursor of claim 9, wherein the IC contact and the opening are nonoverlapping.

### Claim 11 (depends on 9)

The RFID tag precursor of claim 9, further comprising a plurality of openings formed by the etchant in the nonconductive barrier, and wherein the IC contact and at least one of the plurality of openings are nonoverlapping.

### Claim 12 (depends on 9)

The RFID tag precursor of claim 9, wherein at least one of:
the etchant includes a textured surface on the redistribution layer that forms the opening by breaking the nonconductive barrier;
the etchant includes conductive particles that form the opening by breaking the nonconductive barrier;
the etchant forms the opening by reacting with the nonconductive barrier; and
the etchant is included in the adhesive.

### Claim 13 (depends on 9)

The RFID tag precursor of claim 9, wherein the nonconductive barrier is at least one of an oxide and a masking layer.

### Claim 14 (depends on 9)

The RFID tag precursor of claim 9, wherein:
the substrate further includes a second antenna terminal;
the redistribution layer further includes a second portion electrically isolated from the first portion and electrically connected to the IC;
the nonconductive barrier is further present on at least one of the second antenna terminal and the second portion of the redistribution layer; and
the tag precursor further includes a third electrical connection between the second antenna terminal and the second portion of the redistribution layer through another etchant-formed opening in the nonconductive barrier.