Patent Application
20140355226
This application claims priority to and the benefit of Korean Patent Application No. 10-2013-0060597 filed in the Korean Intellectual Property Office on May 28, 2013, the entire contents of which are incorporated herein by reference.
1. Field of Disclosure
The present disclosure relates to a display device. More particularly, the present disclosure relates to the use of an anisotropic conductive film laminate for enabling fine pitch bonding in the display device, and a method of manufacturing the display device.
2. Description of the Related Art
In recent years, various types of display devices have been developed. Examples of these display devices include liquid crystal display (LCD), organic light emitting diode (OLED) display, electrophoretic display, and devices based on other types of display technologies.
A display device typically includes an integrated circuit chip (or a flexible printed circuit substrate) mounted on an edge of a display panel using different packaging means, such as a tape carrier package (TCP), or chip on glass (COG) or chip on film (COF) with an anisotropic conductive film. The resolution of the display device depends in part on the dimensions and pitch of the wires connecting the integrated circuit chip to a substrate. An increase in the resolution of the display device generally requires a corresponding reduction in the dimensions and pitch of the wires.
However, the reduction in dimensions and pitch of the wires may pose certain challenges in the manufacture of the display device. For example, as the dimensions and pitch of the wires decrease, it becomes increasingly difficult to align and bond the integrated circuit chip to the substrate using existing anisotropic conductive films, which may lead to reliability and manufacturing yield issues.
The present disclosure is directed to address at least the above problems relating to the manufacture of high resolution display devices using existing anisotropic conductive films.
According to some embodiments of the inventive concept, an anisotropic conductive film laminate is provided. The anisotropic conductive film laminate includes a first non-conductive film, an anisotropic conductive film disposed on the first non-conductive film, and a second non-conductive film disposed on the anisotropic conductive film, wherein the first non-conductive film has a higher viscosity than the second non-conductive film, and a lower viscosity than the anisotropic conductive film.
In some embodiments, the first non-conductive film may have a viscosity ranging from about 1×105 mPa·s to about 1×109 mPa·s, the anisotropic conductive film may have a viscosity ranging from about 1×107 mPa·s to about 1×1011 mPa·s, and the second non-conductive film may have a viscosity ranging from about 1×103 mPa·s to about 1×107 mPa·s.
In some embodiments, the anisotropic conductive film may include a plurality of conductive particles.
In some embodiments, the conductive particles may have a diameter substantially equal to a thickness of the anisotropic conductive film.
In some embodiments, the conductive particles may have a diameter greater than a thickness of the anisotropic conductive film.
In some embodiments, the conductive particles may have a diameter ranging from about 1 μm to about 10 μm.
According to some other embodiments of the inventive concept, a display device is provided. The display device includes a substrate comprising a mounting region and one or more conductive pads formed in the mounting region, and an external connecting member comprising a connecting region and one or more bumps formed in the connecting region. The substrate and the external connecting member are bonded together at the mounting and connecting regions using an anisotropic conductive film laminate disposed between the conductive pads and bumps. The anisotropic conductive film laminate comprises a first non-conductive film, an anisotropic conductive film disposed on the first non-conductive film, and a second non-conductive film disposed on the anisotropic conductive film, wherein the first non-conductive film has a higher viscosity than the second non-conductive film, and a lower viscosity than the anisotropic conductive film.
In some embodiments, the first non-conductive film may have a viscosity ranging from about 1×105 mPa·s to about 1×109 mPa·s, the anisotropic conductive film may have a viscosity ranging from about 1×107 mPa·s to about 1×1011 mPa·s, and the second non-conductive film may have a viscosity ranging from about 1×103mPa·s to about 1×107mPa·s.
In some embodiments, the anisotropic conductive film may include a plurality of conductive particles.
In some embodiments, the conductive particles may have a diameter substantially equal to a thickness of the anisotropic conductive film.
In some embodiments, the conductive particles may have a diameter greater than a thickness of the anisotropic conductive film.
In some embodiments, the conductive particle may have a diameter ranging from about 1 μm to about 10 μm.
In some embodiments, the external connecting member may include an integrated circuit chip or a flexible printed circuit substrate (FPCB).
According to some further embodiments of the inventive concept, a method of manufacturing a display device is provided. The method includes applying an anisotropic conductive film laminate onto a connecting region of an external connecting member, wherein the connecting region includes one or more bumps formed in the connecting region; aligning the connecting region of the external connecting member to a mounting region of a substrate, wherein the mounting region includes one or more conductive pads formed in the mounting region, and the connecting region is aligned to the mounting region using the bumps and conductive pads as reference; and bonding the external connecting member to the substrate at the connecting and mounting regions via the anisotropic conductive film laminate.
In some embodiments, bonding the external connecting member to the substrate may further include compressing the substrate and the external connecting member with the anisotropic conductive film laminate interposed therebetween, so as to dispose a number of conductive particles between the conductive pads and the corresponding bumps.
The inventive concept will be more fully described herein with reference to the accompanying drawings, in which different embodiments are shown. As those skilled in the art would realize, the inventive concept is not limited to the described embodiments, and the embodiments may be modified in various ways without departing from the spirit or scope of the present disclosure.
In the drawings, the thicknesses of the layers, films, panels, regions, etc., have been exaggerated for clarity. Like reference numerals designate like elements throughout the specification. It is noted that when an element such as a layer, film, region, or substrate is referred to as being formed “on” another element, it can either be formed directly on the other element, or formed on one or more intervening elements located between the two elements. In contrast, when an element is referred to as being formed “directly on” another element, there is no intervening element present between the two elements.
Referring to
In the example of
As previously described, the anisotropic conductive film 120 includes conductive particles 122. The conductive particles 122 are formed of an electrically conductive material (e.g. a metal), so as to provide electrical conductivity to the anisotropic conductive film laminate 100. The conductive particles 122 may be formed in various shapes. As shown in
The first and second non-conductive films 110/130 may include thermosetting adhesive resins, such as bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, resorcinol resin, and other similar types of resins. In some embodiments, the same type(s) of thermosetting adhesive resins may be used in the first non-conductive film 110 and second non-conductive film 130. In some other embodiments, different types of thermosetting adhesive resins may be used in the first non-conductive film 110 and second non-conductive film 130. The resins in the first and second non-conductive films 110/130 may include the types of resins that can be used for the anisotropic conductive film 120.
The first non-conductive film 110 and second non-conductive film 130 provide adhesion of the anisotropic conductive film laminate 100 to an electrical contact (not shown). The electrical contact may include, for example, an electrode or conductive bump disposed on an integrated circuit chip or substrate.
In some embodiments, the thickness of the first non-conductive film 110 may be equal to or less than the thickness of the second non-conductive film 130. For example, when the second non-conductive film 130 has a thickness of about 10 μm, the first non-conductive film 110 may have a thickness of about 5 μm.
In the example of
In general, thermosetting adhesive resins become less viscous at higher temperatures and flow at different speeds depending on their respective viscosities (prior to curing). By varying the viscosities of the first non-conductive film 110, anisotropic conductive film 120, and second non-conductive film 130, the flow speed of each film can be controlled during a bonding process, which typically involves applying heat and pressure (e.g. in a thermocompression bonding process) to the films. In particular, the number of conductive particles 122 collected on an electrode can be maximized by controlling the viscosity (flow speed) of each film, as described below.
During the bonding process, the adhesive resins in the first non-conductive film 110, anisotropic conductive film 120, and second non-conductive film 130 are first transformed from gel to liquid prior to being cured. In some embodiments, the anisotropic conductive film 120 has the highest viscosity among the three layers in the anisotropic conductive film laminate 100 (i.e. the anisotropic conductive film 120 has a higher viscosity than the first and second non-conductive films 110/130). As a result of the different viscosities, the phase transformation from gel to liquid of the adhesive resin 121 in the anisotropic conductive film 120 will be delayed relative to the phase transformations (from gel to liquid) of the adhesive resins in the first and third non-conductive films 110/130. As previously stated, the conductive particles 122 are embedded within the adhesive resin 121. Because the adhesive resin 121 starts flowing at a later time (and more slowly) relative to the resins in the first and third non-conductive films 110/130, the initial distribution of the conductive particles 122 in the anisotropic conductive film 120 can be maintained for a longer period of time during the bonding process. In other words, the reduced fluidity of the adhesive resin 121 reduces the movement/displacement of the conductive particles 122 during the bonding process. Accordingly, the number of conductive particles 122 collected on an electrode can be maximized using the above-described embodiments.
When the anisotropic conductive film laminate 100 is used in the bonding process, the electrical contact (e.g. a bump or electrode) on an integrated circuit chip will protrude into the second non-conductive film 130 during the bonding process. If the second non-conductive film 130 is too viscous, the second non-conductive film 130 will not be adequately displaced during the bonding process, which may subsequently result in electrical opens. Accordingly, in some embodiments, the second non-conductive film 130 has the lowest viscosity among the three layers in laminate 100, so as to ensure that the electrical contact makes contact with the underlying anisotropic conductive film 120 and the opposing electrical pad on the substrate.
In some cases, the diameter of the conductive particles 122 may be greater than the thickness of the anisotropic conductive film 120 (not shown). In those cases, the anisotropic conductive film 120 may be provided with a higher viscosity (relative to the first and third non-conductive films 110/130), so as to reduce the fluidity of the adhesive resin 121. As previously described, the reduced fluidity of the adhesive resin 121 reduces the movement/displacement of the conductive particles 122 during the bonding process, thereby maximizing the number of conductive particles 122 collected on the electrode.
Referring to
The substrate 340 may be divided into a display area and a non-display area surrounding the display area. A display element (not shown) may be formed in the display area of the substrate 340. The display element may include an organic light emitting display element, a liquid crystal display, an electrophoresis display element, or other types of display elements. A portion of the non-display area may be designated as a mounting region. The mounting region may be disposed on an edge of the substrate 340.
In the example of
With reference to
The substrate 340 and external connecting member 350 are bonded together using the anisotropic conductive film laminate 300, which provides both electrical connectivity and mechanical support.
Next, a method of manufacturing an exemplary display device will be described with reference to
With reference to
Next, an anisotropic conductive film laminate 300 is provided. The anisotropic conductive film laminate 300 includes a first non-conductive film 310, an anisotropic conductive film 320, and a second non-conductive film 330. The anisotropic conductive film 320 includes an adhesive resin 321 and conductive particles 322 embedded within the adhesive resin 321. The dimensions of the elements in the anisotropic conductive film laminate 300 may be provided as follows.
In a first embodiment of the anisotropic conductive film laminate (e.g. manufactured by Dexerials), the first non-conductive film 310 may have a thickness of about 4 μm; the anisotropic conductive film 320 may have a thickness of about 8 μm; the second non-conductive film 330 may have a thickness of about 10 μm; and the conductive particles 322 may have a diameter of about 3.2 μm.
In a second embodiment, the first non-conductive film 310 may have a thickness of about 4 μm; the anisotropic conductive film 320 may have a thickness of about 3.2 μm; the second non-conductive film 330 may have a thickness of about 10 μm; and the conductive particles 322 may have a diameter of about 3.2 μm. It is noted that the second embodiment is representative of the anisotropic conductive film laminate 200 in
In a third embodiment, the first non-conductive film 310 may have a thickness of about 5 μm; the anisotropic conductive film 320 may have a thickness of about 3 μm; the second non-conductive film 330 may have a thickness of about 10 μm; and the conductive particles 322 may have a diameter of about 3.2 μm.
In each of the above-described embodiments, the anisotropic conductive film 320 may have a viscosity of about 109 mPa·s; the first non-conductive film 310 may have a viscosity of 107mPa·s; and the second non-conductive film 330 may have a viscosity of 105mPa·s, wherein the viscosity of each of the above film layer is measured at a temperature of about 100° C.
Next, the anisotropic conductive film laminate 300 may be laminated on a surface of the external connecting member 350 over the bumps 370. In some particular embodiments, the anisotropic conductive film laminate 320 may be laminated on a surface of the substrate 340 over the conductive pads 360.
Next, the substrate 340 and external connecting member 350 are aligned (using the bumps 370 and conductive pads 360 as reference) and brought into proximate contact with each other, with the anisotropic conductive film laminate 300 interposed between the substrate 340 and external connecting member 350.
Next, the substrate 340 and external connecting member 350 are bonded together using a bonding process to form the display device of
As previously described, the adhesive resins in the first non-conductive film 310, anisotropic conductive film 320, and second non-conductive film 330 become less viscous and undergo phase transformations from gel to liquid when heat and/or pressure is applied. During the bonding process, the liquid resins flow and fill in the space between the bumps 360 and conductive pads 360, as well as the gap between the substrate 340 and external connecting member 350. In some embodiments, the anisotropic conductive film 320 has the highest viscosity (relative to the first and second non-conductive films 310/330). As a result, the phase transformation from gel to liquid of the adhesive resin 321 in the anisotropic conductive film 320 will be delayed relative to the phase transformations (from gel to liquid) of the adhesive resins in the first and third non-conductive films 310/330. The resins flow at different rates during the bonding process, with the flow rate of the adhesive resin 321 being the slowest (relative to the resins in the first and second non-conductive films 310/330). Accordingly, the slow flow rate and delayed phase transformation of the adhesive resin 321 limit the motion/displacement of the conductive particles 322 during the bonding process. As such, the initial distribution of the conductive particles 322 in the anistropic conductive film 320 can be maintained for a longer period of time during the bonding process. Accordingly, the number of conductive particles 322 collected between the conductive pads 360 and bumps 370 can be maximized. Furthermore, the above-described embodiments allow fine-pitched electrical connections to be formed, thereby enabling high resolution display devices.
In some embodiments, the first non-conductive film 310 may be omitted from the anisotropic conductive film laminate 300 so as to form a two-layer laminate structure. However, it is noted that the number of conductive particles 322 collected between the conductive pads 360 and bumps 370 may be fewer in a two-layer laminate structure compared to a three-layer laminate structure. For example, in some embodiments, the number of conductive particles collected between the conductive pads and the bumps is 10% more in a three-layer laminate structure compared to a two-layer laminate structure.
While this inventive concept has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the inventive concept is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2013-0060597 | May 2013 | KR | national |
