KR20090023776A - Rfid tag and laser-strap bonding method thereof - Google Patents

Abstract

A strap bonding method using a strap bonding-type RFID tag and the laser is provided to offer the flexibility and enable proper electrical connection, mechanical joining and position designation. A base substrate, a strap member and an anisotropic conductive film are arranged in a line(S10). The base substrate has a metal pattern for an antenna and a connection terminal. In the strap member, an IC chip for wireless communication and conductive leads are formed. The anisotropic conductive film is formed between the base substrate and strap member. By using the vision, marks indicated on the base substrate, strap member and anisotropic conductive film are confirmed and then are arranged(S20). A release paper is stripped from the anisotropic conductive film and a glass substrate is arranged on the upper part of a strap. As the result, the base substrate and strap are temporarily coupled(S30).

Description

Strap bonding method using strap bonding type RDF tag and laser {RFID TAG AND LASER-STRAP BONDING METHOD THEREOF}

The present invention relates to a RFID (Radio Frequency IDentification) tag and a strap bonding method thereof for exchanging information with an external device in a non-contact manner. More specifically, the present invention relates to a strap bonding RFID tag and a strap bonding method using a laser having excellent bonding strength and communication performance.

In general, RFID tags are widely used, such as logistics management and access / exit management, by exchanging information related to identification codes for identifying objects by contactless wireless communication with external devices.

Such RFID tags may take various forms, such as disks, smart cards, plastic housings or labels, and have a combination of antennas and analog and / or digital electronics, which may be e.g. communication electronics, data memory. And control logic.

For example, RFID tags are used in conjunction with security-locks in vehicles to control access to buildings, tracking inventory and parcels.

Typically, RFID tags are manufactured by patterning, etching, or printing a metal pattern for an antenna on a dielectric substrate and combining the metal pattern for the antenna with an integrated circuit chip.

Since such an RFID tag must be flat and bendable because it must be attached or fixed to another object in an external environment, it is desirable to avoid materials or configurations that add inadequate thickness or strength.

It would also be desirable to be able to properly place components (chips, chip connectors, antennas), electrical connections, mechanical junctions, and appropriate positioning.

In addition, as RFID tags are increasingly miniaturized, the precision and resolution of the printing elements of lines and spaces are very important when thinly depositing or etching metal patterns, as they govern the communication performance of the chip and the entire RFID tag.

On the other hand, since the bonding failure rate is low and the cost is low as the bonding method of the RFID tag, the wire bonding method is widely used.

However, such a wire bonding method must be molded after the wire bonding to prevent mechanical support and interference with the outer strap to prevent the wire from being exposed to the outside.

In addition, wire bonding has a problem in that the bonding material and the molding material have rigidity, and not only reduce the flexibility of the RFID tag but also cannot thin the film.

In addition, there is a problem in that the precision suitable for joining the fine metal pattern due to the miniaturization of the RFID tag cannot be provided and the joining process time increases.

In addition, a semiconductor flip chip method is widely used as a method of bonding RFID tags.

This flip chip method applies an anisotropic adhesive to a pad, and then places an antenna metal pattern and an integrated circuit chip up and down and applies pressure to melt-cure at a high temperature using a hot plate to prevent bonding of the RFID tag. to provide.

However, this flip chip method requires not only a long bonding processing time but also a long time because the hot plate must be maintained at a constant temperature after heating the hot plate to a high temperature from 180 to 250 ° C. and subjected to a high temperature heat treatment under pressure for at least 10 seconds. Since the thermal effect is received by the integrated circuit chip or the conductive lead, the defect rate is large, and there is a problem that it cannot be applied to minute lines or patterns.

In addition, in order to solve the problem of recently adjacent metal straps deteriorating communication performance and to thin and flatten an RFID tag, an integrated circuit chip and a strip on which conductive leads are formed and a base substrate on which an antenna metal pattern is formed are separately formed. A strip bonding method for bonding these using anisotropic conductive films has been proposed.

The strip bonding method has an advantage of not needing a separate molding process due to the thermosetting resin included in the anisotropic conductive film, but it takes a long time since the bonding process takes longer because the anisotropic conductive film is melted using a hot bar. However, due to various processing variables, the anisotropic conductive film is hardened unevenly, and the metal grains dispersed in the anisotropic conductive film are entangled in the metal pattern, resulting in high bonding failure rate. There was a problem that could not be.

SUMMARY OF THE INVENTION The present invention has been made to solve this technical problem, and an object of the present invention is to provide flexibility, and to properly connect electrical components, mechanical joints, and appropriate components (chips, chip connectors, antennas). The method of strap bonding using a strap bonding RFID tag and a laser that can be positioned in the same manner, can increase the precision and resolution of the printed elements of thinly deposited or etched metal lines and spaces, thereby improving communication performance. To provide.

A strap bonded RFID tag according to an embodiment of the present invention includes a base substrate having a metal pattern for an antenna and a connection terminal electrically connected to the antenna metal pattern on a base portion;

A strap having an integrated circuit chip for wireless communication and conductive leads formed on the strap substrate;

Bonding part which pressurizes an anisotropic conductive film simultaneously with laser beam irradiation and hardens it quickly, and forms uniform conductive ball pressure and provides excellent bonding strength between 2000gf / mm2 and 4000gf / mm2 between the base terminal and the strap. It is characterized by including.

Strap bonding method of an RFID tag using a laser according to an embodiment of the present invention,

Supplying a base substrate having a metal terminal for antenna and a connection terminal electrically connected to the antenna pattern on the base portion;

Supplying a strap member having a wireless communication integrated circuit chip and conductive leads formed thereon;

Peeling and arranging the anisotropic conductive film under the strap substrate;

Positioning the base substrate, the strap member, and the anisotropic conductive film so as to correspond to each other, and arranging a glass substrate to face the strap member;

And pneumatically pressurizing the glass substrate and irradiating a laser beam to perform strap bonding.

Strap bonded RFID tags according to one embodiment of the present invention can provide flexibility and can be suitably electrically connected, mechanically bonded, and properly positioned with components (chips, chip connectors, antennas). And increase the precision and resolution of the printed elements of thinly deposited or etched metal lines and spaces to increase communication performance.

In addition, the strap bonding method of the RFID tag using a laser according to an embodiment of the present invention can be automated by using a laser, it can shorten the RFID strap bonding process time, reduce the defect rate of bonding, and can be bonded in a plane This eliminates the need for separate molding and allows other components to be less thermally affected.

In addition, the strap bonding method of an RFID tag using a laser according to an embodiment of the present invention may provide a strap bonded RFID tag with increased bonding strength and improved communication performance.

Hereinafter, a strap bonding method of an RFID tag using a strap bonding type RFID tag and a laser according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view for schematically showing a configuration of an RFID tag according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating a strap bonding state of an RFID tag shaped using a laser according to an embodiment of the present invention. One picture.

Referring to FIG. 1, the RFID tag 1 according to an embodiment of the present invention electrically connects the base substrate 10, the strap member 20, and the base substrate 10 and the strap member 20. It consists of a bonding part 30 for mechanically bonding.

The base substrate 10 may include a base portion 11 formed of a sheet form by selecting one of PET film, PI film, ceramic, and FR4, and an antenna formed on the base portion 11 by deposition or etching. The metal pattern 13 is included. The antenna metal pattern 13 is illustrated in a shape extending linearly on both sides with a connection terminal portion 13a to which an IC chip, which will be described later, is bonded, but is not limited thereto. On the other hand, the connection terminal portion 13a may be formed in a groove shape in the base portion 21 so that the thickness may be maintained even when combined with the IC chip 23 described later.

The strap member 20 is fixed to the strap base portion 21 and a strap base portion 21 made of a sheet form by selecting one of the PET film, PI film, ceramic, and FR4, and with an adhesive or the like. And an IC chip 23 capable of exchanging information by performing wireless communication with an external device through the antenna metal pattern 13, and a conductive lead 25 extending linearly from both sides of the IC chip 23. .

The bonding part 30 according to an embodiment of the present invention is formed by irradiating and curing a laser beam while pressing an anisotropic conductive film (ACF) with a buffer pressing jig or the like.

Anisotropic conductive film is a film-like adhesive in which conductive particles (such as conductive balls), such as metal-coated plastic or metal particles, are dispersed. According to an embodiment of the present invention, connection reliability is achieved by heat curing using a laser beam. This is improved and the connection pitch can be made fine.

According to one embodiment of the present invention, the anisotropic conductive film is configured to disperse fine conductive balls having a size of about 3 to 30um in an adhesive layer having a thickness of about 15 to 50um, and the connection terminal portion 13a of the base substrate 10 ) And the laser beam in the IR wavelength band of 800 to 1200 nm from the oscillation unit 110 of the laser system 100 after being disposed correspondingly between the conductive lead of the strap member 20 and about 160 to an output of 8 to 15 W. Irradiate the laser beam for 1 to 3 sec in the temperature range of ˜180 ° C.

At this time, when the glass substrate 50 disposed on the upper surface of the strap member 20 is pressed by 5 to 20 kg / cm 2 by the pneumatic pressing jig 60, the connection of the conductive ball in which the ACF adhesive is melted and dispersed is replaced. Conductive is obtained by connecting between the terminal portion 13a and the corresponding lead 25 of the strap member 20, while an ACF adhesive wraps these connections.

Accordingly, conductivity is obtained in the vertical direction between the base substrate 10 and the strap member 20, and mechanical coupling between the conductive particles and the metal pattern may be maintained by high adhesive force of the adhesive to impart connection reliability. .

In addition, because of the use of a laser, even if the metal pattern is fine, poor connection may not occur, and thermal effects may be minimized because the absorption of the metal pattern or the base substrate is low by a non-contact process.

As shown in FIG. 2, since the spot size of the laser beam is generally small to about 2 mm or less, the laser beam must be moved or irradiated several times to fill the connection terminal portion, so that the processing efficiency may be reduced, and the laser beam is uniformly irradiated. Since it is not possible, you can see through the picture that the challenge ball pressure is uneven.

According to an embodiment of the present invention, in order to solve this problem, in a laser system, by using a convex lens or the like, the focus position is moved upward so that the spot size corresponds to the width of the conductive lead and instead the output is increased. The laser beam was uniformly welded corresponding to the shape of the connecting terminal portion 13a.

In addition, the profile of the laser beam may be shaped to correspond to the shape of the connection terminal portion 13a and irradiated at once so that the laser beam may be uniformly spread over the entire area.

In addition, by irradiating a plurality of laser beams through a plurality of laser heads 120 may combine these laser beams so as to correspond to the shape of the conductive lead to weld uniformly and simultaneously bond a plurality of strips.

In this way, by irradiating a laser beam of a uniform output to the junction portion, the conductive ball was melted unevenly in the past, so that the conduction path over the entire area of the junction could not be formed, and thus the problem of poor connection could be solved.

3 is a flowchart illustrating a strap bonding method of an RFID tag using a laser according to an embodiment of the present invention, and FIGS. 4A and 4B are straps of an RFID tag using a laser according to an embodiment of the present invention. 5 is a graph illustrating a relationship between bonding strength of a bond and an output of a laser, and FIG. 5 is a graph illustrating a relationship between bonding strength of a strap bonding of an RFID tag using a laser and laser processing time according to an embodiment of the present invention.

As shown in FIG. 3, the RFID tag strap bonding method using a laser according to an embodiment of the present invention is electrically connected to the antenna metal pattern 13 and the antenna metal pattern to the base 11. A base substrate 10 having a terminal portion 13a, a strap member 20 having an integrated circuit chip 23 and conductive leads 25 for wireless communication formed on the strip base substrate 21, and the base substrate 10; Arrange the anisotropic conductive film 30 side by side between the strap member 20 (S10), using the vision to check the marks on the base substrate and the strap, and the anisotropic conductive film to align the position (S20) Peeling the release paper from the anisotropic conductive film and arranging a glass substrate on the upper strap to temporarily couple the base substrate and the strap (S30), and simultaneously pressurize the glass substrate with a laser beam Irradiating to perform the strap bonding coupling (S40).

At this time, the laser is directed upward to form a profile of the laser beam in a shape corresponding to the shape of the conductive lead 25 of the strap member 20 so that the conductive balls of the anisotropic conductive film 30 can be uniformly fused. The output of the laser beam, the irradiation time, the profile, etc. may be prepared by analyzing the pushed photograph of the conductive ball in advance while controlling the output while moving (S41).

At this time, the glass substrate is disposed to be able to transmit the laser beam while providing a pressing force. The glass substrate is precisely driven by a sub-motor and a pneumatic pressing jig 60 is disposed using a pneumatic cylinder to elastically move the glass substrate 5 to 20 kg / cm ^2. It can be pressurized for 1 to 3 seconds under load.

The pneumatic pressing jig 60 may apply a uniform pressure regardless of the form of the strap by supplying a silicon sheet downward and pressurizing the silicon sheet to effectively compress the anisotropic conductive film.

The laser is preferable because it can provide a uniform output for 1 to 3 seconds using a diode laser having a wavelength of 800 to 1200nm well transmitted to the silicon sheet and the glass substrate.

The laser is preferably of the CW type because it can provide a uniform output during the irradiation time of the laser beam, and the connection terminal portion 13a in a state where the focus of the laser beam is moved upward by using a convex lens or the like. To correspond to the shape of.

In this case, the output of the laser preferably has an output of a square multiple of the upward movement distance in the same way as the laser output in the focused state, and the temperature of 180 to 200 ° C. can be quickly obtained by irradiating for 1 to 3 seconds, and the constant It can be kept hard and can be hardened quickly. Therefore, since the bonding processing time which took about 10 seconds or more when using a hot bar can be reduced to 1 to 3 seconds, the tag time can be significantly reduced.

Meanwhile, referring to FIGS. 4A and 4B, FIGS. 4A and 4B are laser outputs 8 to 4 when the base 11 of the RFID tag 1 is a PET film and a PI film according to an embodiment of the present invention. It can be seen that the bonding strength of 2000 to 4000 gf / mm 2 is shown at 15 W.

Looking at the Patent Publication No. 10-2005-0025181 it can be seen that an increase of about four times or more compared to 808gf / mm2, the bonding strength when the strap of the RFID tag using a hot bar and underfill.

Therefore, it can be used for a long time that the RFID film in the form of a thin film is peeled off or damaged.

In addition, referring to Figure 5, according to an embodiment of the present invention, it can be seen that the bonding strength of 2000 to 4000 gf / mm2 when the irradiation time of the laser beam is 1 to 3 seconds.

RFID tag strap bonding method using a laser according to an embodiment of the present invention can be modified and applied in various forms within the scope of the technical idea of the present invention.

Therefore, the embodiments and the drawings are only for the purpose of describing the contents of the invention in detail, and are not intended to limit the scope of the technical idea of the invention, the scope of the present invention is not limited to the claims to be described later, the equivalent scope thereof It should be judged including.

1 is an exploded perspective view for schematically showing a configuration of an RFID tag according to an embodiment of the present invention;

2 is a photograph of a strap bonding state of an RFID tag using a laser according to an embodiment of the present invention;

3 is a flowchart illustrating a strap bonding method of an RFID tag using a laser according to an embodiment of the present invention;

4A and 4B are graphs showing the relationship between the bonding strength of the strap bonding of the RFID tag using the laser and the output power of the laser, according to an embodiment of the present invention;

5 is a graph showing the relationship between the bonding strength of the strap bonding of the RFID tag using a laser and the laser processing time according to an embodiment of the present invention.

Claims (14)

In the strap bonding method of an RFID tag using a laser, Supplying a base substrate having a metal terminal for antenna and a connection terminal electrically connected to the antenna pattern on the base portion; Supplying a strap member having a wireless communication integrated circuit chip and conductive leads formed thereon; Peeling and arranging the anisotropic conductive film under the strap substrate; Positioning the base substrate, the strap member, and the anisotropic conductive film so as to correspond to each other, and arranging a glass substrate to face the strap member; And elastically pressing the glass substrate and irradiating a laser beam to perform strap bonding. The method of claim 1, The strap bonding step includes the step of moving the focus of the laser beam in the upward direction to match the spot size of the laser to the area of the strap connection terminal portion strap bonding method of the RFID tag using a laser. The method of claim 1, The laser is a strap bonding method of an RFID tag using a laser which is a CW type diode laser using 800 to 1200nm. The method of claim 1, Strap bonding method of an RFID tag using a laser that increases the output of the laser by the square of the upward movement distance from the laser focus. The method of claim 1, The base substrate is a strap bonding method of an RFID tag using a laser including a base portion made of a sheet form by selecting one of PET film, PI film, ceramic, and FR4. The method of claim 1, Strap bonding method of an RFID tag using a laser pressing the glass substrate at a pressure of 5 to 20kg / cm ₂ by a pneumatic pressure jig at the same time as the irradiation of the laser. The method of claim 1, The pneumatic pressure jig is a strap bonding method of the RFID tag using a laser to press the strap member under the silicon sheet via the silicon. The method of claim 1, And a laser beam for 1 to 3 seconds to provide strap bonding with a bonding strength of 2000 to 4000 gf / mm 2. The method of claim 1, Strap bonding method of an RFID tag using a laser to determine the output of the laser beam, the profile and irradiation time by observing the conductive ball pressure when the strap bonding through the vision. The method of claim 1, And a laser having a plurality of head portions, and irradiating a plurality of laser beams through the plurality of head portions to provide a uniform intensity profile corresponding to an area of a predetermined connection terminal portion. A base base part having a metal part for an antenna and a connection terminal part electrically connected to the metal pattern for an antenna; A strap member having an integrated circuit chip for wireless communication and conductive leads formed on a strip base substrate; Strap bonding type RFID tag including a bonding portion that provides excellent bonding strength between 2000gf / mm2 and 4000gf / mm2 between the base terminal and the strap by hardening the anisotropic conductive film at the same time as the laser beam irradiation. . The method of claim 11, wherein Strap bonding type RFID tag to form a uniform plane conductive ball pressure on the bonding portion. The method of claim 11, wherein The base member is a strap-bonding RFID tag made of a sheet form by selecting one of PET film, PI film, ceramic, and FR4. The method of claim 11, wherein The bonding portion is a strap bonding RFID tag formed of a fine conductive ball of about 3 to 30um thick and an adhesive layer of about 15 to 50um of the anisotropic conductive film.

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