TWI606466B - Nuclear layer technology anisotropic conductive film - Google Patents

Description

Nuclear layer technology anisotropic conductive film

The invention relates to an anisotropic conductive adhesive film and a manufacturing method thereof, in particular, the conductive adhesive layer sandwiched between the upper adhesive layer and the lower adhesive layer comprises an insulating substrate and a plurality of conductive particles, and is a single The particle thickness is distributed in the insulating substrate or on the surface of the insulating substrate.

The physical connection between different electronic components is most commonly used by soldering, mainly by using a tin-tin alloy with a lower melting point as a solder, and melting the solder instantaneously under appropriate heating to contact the pins of the two electronic components when the heating is removed. The solder can be solidified and firmly connected to the two electronic components. Another way is to use a high-temperature tin furnace to place the surface-mount technology (SMT) electronic components on the electrical circuit with solder beforehand. After the instant heating and cooling of the high-temperature furnace, the solder can be connected. Electronic component.

However, the traditional lead-lead reflow process cannot be applied to applications that require thin, short, and low power consumption, such as Thin Film Transistor Liquid Crystal Display (TFT-LCD) (Integrated Circuit, IC). The connection to the substrate is because the pitch of the gold bumps used to connect the external circuits in the driver IC is generally small, about 20 um to 40 um, and the melting point of the gold bumps is relatively higher than that of the tin-lead bumps. Therefore, at present, a bonding method using an anisotropic conductive film (ACF: Anisotropic Conductive Film) is mainly used.

The composition of ACF mainly comprises conductive particles and insulating rubber materials. The conductive particles are contained in the insulating rubber material. Because the insulating rubber material has viscosity under heating, and under the external vertical pressure, the conductive particles move in the pressure direction. Further, they are in contact with each other or are pressed and deformed, thereby forming an electrical conduction effect in the vertical direction of the pressed, but the electrically conductive particles are still separated by the insulating rubber in the horizontal direction of the uncompressed to form an insulating electrical. State, when the insulating rubber is cured after a period of time, the conductive particles are no longer moved by external force to form a vertical conduction but horizontal Stable structure with insulation. Therefore, the TFT-LCD driver IC is formed into a good electrical connection with the substrate.

The types of conductive particles can be classified into carbon black, metal balls, and resin balls coated with metal. Carbon black is an early product and is currently not used much. The metal ball is made of nickel balls. The advantage is that it has high hardness and low cost. The sharp-angled protrusions can be inserted into the joint to increase the contact area. The disadvantage is that it may damage the weak joint, easily oxidize and affect the conduction. In order to overcome the oxidation problem of the nickel ball, the surface of the nickel ball can be plated with gold to become a gold-plated nickel ball. At present, the conductive particles of the nickel sphere are mostly used for connection with the PCB, and the ITO electrode connection of the LCD panel is not applicable. The main reason is that the metal sphere is hard and has many sharp corners, which may cause damage to the ITO line. Therefore, the ACF used for TFT-LCD is mainly made of gold-plated nickel resin ball. Because the resin ball has elasticity, it will not damage the ITO circuit, and in the process of pressure bonding, the sphere will be deformed into an ellipsoid to increase Contact area.

The conductive particles in ACF play a key role in vertical conduction. The more the number of conductive particles in the insulating rubber or the larger the volume of the conductive particles, the smaller the contact resistance in the vertical direction, and the better the conduction effect. However, excessive or excessive conductive particles may be easily contacted with each other when the thermal bonding is performed, causing a short-circuit of the lateral conduction, causing an electrical function to be abnormal or even failing to cause damage to the entire TFT-LCD. In particular, TFT-LCD resolution requirements are increasing, and the number of pins of the driver IC is also increasing, and the size of the gold bumps and the connection pads on the substrate is increasingly narrower, that is, toward a fine pitch. (fine pitch).

In order to maintain a sufficient amount of conduction and conduction in the case where the contact area is reduced, it is necessary to increase the trapping rate of the conductive particles, and thus it is necessary to increase the amount of the conductive particles added, which not only increases the manufacturing cost but is not conducive to market competition, and also increases the conductivity. The amount of particles added reduces the lateral electrical insulation, because the lateral conductive particles may contact each other due to the effect of lateral pressing to form electrical conduction, and even cause short-circuiting of adjacent pins or gold bumps. as a result of.

In addition, in the conventional technology, the conductive particles in the conductive film are freely scattered, so when the heat is pressed, if the partially displaced conductive particles are not captured, the conductive effect cannot be obtained, or the trapping is not possible. Insufficient number of conductive particles can cause poor electrical conductivity and affect electrical quality.

Therefore, there is a need for an innovative nuclear layer technology anisotropic conductive film, which utilizes an upper adhesive layer and a lower adhesive layer to sandwich a conductive adhesive layer comprising an insulating substrate and conductive particles. The fluidity of the upper adhesive layer and the lower adhesive layer when heated and pressurized is greater than that of the insulating substrate, and particularly the conductive particles of the conductive adhesive layer are distributed in the insulating substrate or on the surface of the insulating substrate in a single particle thickness. Therefore, at most only a single conductive particle in the vertical direction of the insulating substrate, to avoid short-circuiting of the pin with small pitch in the integrated circuit due to accumulation of excessive conductive particles, the yield can be greatly improved, thereby solving the problem of the above-mentioned conventional technology.

The main purpose of the present invention is to provide a core layer technology anisotropic conductive film, which mainly comprises an upper adhesive layer, a conductive adhesive layer and a lower adhesive layer which are sequentially stacked, wherein the upper adhesive layer and the lower adhesive layer are the same or different. The electrical insulating material is composed of an insulating substrate and a plurality of conductive particles, and the conductive particles are distributed in the insulating substrate or on the surface of the insulating substrate in a single particle thickness. That is, there is at most a single conductive particle in the vertical direction of the insulating substrate.

The fluidity of the upper adhesive layer and the lower adhesive layer when heated and pressurized is greater than the flowability of the insulating substrate in the conductive adhesive layer under heat and pressure, so that the entire nuclear layer technical anisotropic conductive film is heated and pressurized. The upper adhesive layer and the lower adhesive layer may have a higher rate of flow or deformation than the insulating substrate.

The above electrical insulating material may comprise a thermosetting, thermoplastic resin such as an epoxy resin, a phenol resin, a silicone resin, an acrylic resin, a phenoxy resin, a polyester resin, a polyurethane resin, a polyamide resin, a polyolefin resin, Acrylic rubber, synthetic rubber, natural rubber. The insulating substrate of the conductive adhesive layer may comprise pressure sensitive adhesive, thermosetting or thermoplastic resin, such as epoxy resin, phenol resin, epoxy resin, acrylic resin, phenoxy resin, polyester resin, polyurethane resin, polyfluorene. Amine resin, polyolefin resin, acrylic rubber, synthetic rubber, natural rubber.

The conductive particles may be nickel-plated gold balls of a resin, mainly comprising a resin core, a nickel plating layer and a gold layer, wherein the nickel plating layer covers the resin core, and the gold layer covers the nickel plating layer, so the surface gold layer of the conductive particles has Excellent electrical conductivity.

Therefore, the core layer technology anisotropic conductive film of the present invention is suitable for electrical connection integrated circuit and circuit board, especially thin indium tin oxide which is connected to a glass substrate by a small pitch integrated circuit pin. The (ITO) layer enables the conductive particles of the integrated circuit and the indium tin oxide layer to be contacted to the pin and the indium tin oxide layer simultaneously to reach the electrical connection. For the purpose of connection, part of the adhesive layer and the lower adhesive layer are pushed at the time of pressing to fill the gap between the adjacent pins and the void of the indium tin oxide layer, and are not pinned and indium tin The conductive particles pressed up and down by the oxide layer remain in their original state without being in contact with any pins or indium tin oxide layers to form electrical insulation.

10‧‧‧Upper glue layer

20‧‧‧conductive adhesive layer

21‧‧‧Insulation substrate

22‧‧‧Electrical particles

30‧‧‧Under layer

40‧‧‧Integrated circuit

42‧‧‧ feet

50‧‧‧ boards

52‧‧‧ circuit pattern

The first figure shows a schematic diagram of an anisotropic conductive film of a core layer technique in accordance with an embodiment of the present invention.

The second figure shows a schematic diagram of an application example of an anisotropic conductive film according to the core layer technique of the present invention.

The embodiments of the present invention will be described in more detail below with reference to the drawings and the reference numerals, which can be implemented by those skilled in the art after having studied this specification.

Please refer to the first figure, a schematic diagram of an anisotropic conductive film of a core layer technology according to an embodiment of the invention. As shown in the first figure, the core layer technical anisotropic conductive film of the embodiment of the invention mainly comprises an upper adhesive layer 10, a conductive adhesive layer 20 and a lower adhesive layer 30, which are sequentially stacked from top to bottom to form a film. a stacked structure in which the conductive adhesive layer 20 is composed of an insulating substrate 21 and a plurality of conductive particles 22, and the conductive particles 22 are distributed in the insulating substrate 21 or in the insulating substrate 22 in a single particle thickness manner. On the surface, the figure shows an example in which the conductive particles 22 are distributed in the insulating substrate 21, that is, at most only a single conductive particle 22 in the vertical direction of the insulating substrate 21.

The upper adhesive layer 10 and the lower adhesive layer 30 may be made of the same or different electrical insulating materials, including a thermosetting, thermoplastic resin such as an epoxy resin, a phenol resin, a silicone resin, an acrylic resin, a phenoxy resin, a polyester resin, and a poly An amine resin, a polyamide resin, a polyolefin resin, an acrylic rubber, a synthetic rubber, a natural rubber, and the insulating substrate 21 of the conductive adhesive layer 20 may contain a pressure sensitive adhesive, a thermosetting resin, a thermoplastic resin such as an epoxy resin or a phenol resin. , enamel resin, acrylic resin, phenoxy resin, polyester resin, polyurethane resin, polyamide resin, polyolefin resin, acrylic rubber, synthetic rubber, natural rubber.

The conductive particles 22 are conductive particles having a particle size of about 2.5 to 10 um, and a specific example may be a resin nickel-plated gold ball, mainly comprising a resin core, a nickel plating layer and a gold layer, wherein nickel plating The layer is coated with a resin core, and the gold layer is coated with a nickel plating layer, so that the surface of the conductive particles is a gold layer and has excellent electrical conductivity.

Specifically, the conductive paste layer 20 described above may be realized by a transfer method, or may be formed by directly mixing the insulating base material 21 and the conductive particles 22 by mixing and stirring, and then spraying or coating.

In addition, the fluidity of the upper rubber layer 10 and the lower rubber layer 30 when heated and pressurized is greater than the fluidity of the insulating substrate 21 in the conductive adhesive layer 20 when heated and pressurized, so that the entire nuclear layer technology is anisotropic conductive film. When heated and pressurized, the flow rate or degree of deformation of the upper subbing layer 10 and the lower subbing layer 30 may be greater than that of the insulating substrate 21.

In order to further illustrate the features of the present invention, reference may be made to the second figure, which is a schematic diagram of an application example of the anisotropic conductive film of the core layer technology of the present invention. As shown in the second figure, the core layer technology anisotropic conductive film of the present invention is a combination of the integrated circuit 40 and the circuit board 50 under the heating and pressing, wherein the integrated circuit 40 includes a plurality of connections. The foot 42 and the circuit board 50 have a circuit pattern 52, such as the circuit board 50 being an electrically insulating glass substrate and the circuit pattern 52 being a conductive, thin indium tin oxide (ITO) layer.

Since the conductive particles 22 which are pressed up and down by the pin 42 of the integrated circuit 40 and the road pattern 52 directly contact the pin 42 and the road pattern 52, the corresponding pin 42 and the circuit pattern 52 form an electrical connection, and the upper portion The glue layer 10 and the lower glue layer 30 are deformed and flow by being pressed by heat, thereby filling the gap between the adjacent pins 42 and filling the gap of the circuit pattern 52 at the same time. In addition, the conductive particles 22 that are not pressed by the pins 42 and the circuit pattern 52 remain in their original state without being in direct contact with any of the pins 42 and the circuit pattern 52, that is, electrical insulation is formed.

Accordingly, the corresponding pins 42 and circuit patterns 52 can be properly electrically connected via the extruded conductive particles 22 and have a very low junction resistance because the actual contacts to the pins 42 and the circuit pattern 52 are conductive particles. 22 outermost gold layer. Moreover, the upper adhesive layer 10 and the lower adhesive layer 30 are heated to be extruded, deformed, and flowed to a greater extent than the insulating base material 21 of the conductive adhesive layer 20, so the insulating substrate 21 can be kept almost stationary, and the corresponding conductive therein The particles 22 are still in the original position such that the deformed, flowing upper rubber layer 10 and the lower rubber layer 3 fill the gap between the adjacent pins 42 and the gap of the circuit pattern 52, respectively.

In summary, the main feature of the anisotropic conductive film of the core layer technology of the present invention is that It is suitable for electrical connection integrated circuits and circuit boards, especially integrated circuits with small pitch (Pitch), such as pitch less than 40um, or 15um pitch, which can be electrically connected to the board via conductive particles. The circuit pattern or the transparent conductive layer of the glass substrate, such as the ITO layer, greatly improves the yield of the electrical connection, and can avoid short circuit of the circuit of the integrated circuit or the circuit pattern of the circuit board due to the accumulation of excessive conductive particles.

Since the technology of the present invention is not found in published publications, periodicals, magazines, media, exhibition venues, and thus is novel, and can be implemented by breaking through the current technical bottlenecks, it is indeed progressive. In addition, the present invention can solve the problems of the conventional technology, improve the overall use efficiency, and can achieve the value of industrial utilization.

The above is only a preferred embodiment for explaining the present invention, and is not intended to limit the present invention in any way, and any modifications or alterations to the present invention made in the spirit of the same invention. All should still be included in the scope of the intention of the present invention.

10‧‧‧Upper glue layer

20‧‧‧conductive adhesive layer

21‧‧‧Insulation substrate

22‧‧‧Electrical particles

30‧‧‧Under layer

Claims (7)

A core layer technology anisotropic conductive film, comprising: an upper adhesive layer, electrically insulating, is composed of an electrical insulating material; a conductive adhesive layer comprising an insulating substrate and a plurality of conductive particles, and the like The conductive particles are distributed on a surface of the insulating substrate in a single particle thickness such that the insulating substrate has at most only a single conductive particle in the vertical direction; and the lower adhesive layer is electrically insulated and is the same as Or an electrically insulating material different from the upper adhesive layer, wherein the upper adhesive layer, the conductive adhesive layer and the lower adhesive layer are sequentially stacked from top to bottom to form a film-like stacked structure, and the upper portion The adhesive layer and the lower adhesive layer are separately and independently processed, and the insulating base material of the conductive adhesive layer comprises synthetic rubber or natural rubber, pressure sensitive adhesive, thermosetting resin or thermoplastic resin for mixing. The nuclear layer technical anisotropic conductive film according to the first aspect of the patent application, wherein the upper adhesive layer and the electrical insulating material of the lower adhesive layer comprise a thermosetting resin and a thermoplastic resin. The nuclear layer technical anisotropic conductive film according to claim 2, wherein the upper adhesive layer and the electrical insulating material of the lower adhesive layer comprise epoxy resin, phenol resin, epoxy resin, acrylic resin, phenoxy resin , polyester resin, polyurethane resin, polyamide resin, polyolefin resin, synthetic rubber or natural rubber. The core layer technical anisotropic conductive film according to claim 1 of the patent application, wherein the conductive particles have a particle size of 2.5 to 10 um. The nuclear layer technical anisotropic conductive film according to claim 1 of the patent application, wherein the conductive particles are disposed on the insulating substrate by means of a transfer. According to the nuclear layer technical anisotropic conductive film of claim 1, wherein the insulating substrate and the conductive particles are mixed by mixing, and then sprayed or coated to form the conductive adhesive. Floor. According to the nuclear layer technical anisotropic conductive film of claim 1, wherein the upper adhesive layer and the lower adhesive layer have a fluidity greater than that of the conductive adhesive layer in the conductive adhesive layer. Mobility during pressure.