JP4207838B2 - Connecting material - Google Patents

Description

  The present invention relates to a connection material for connecting to-be-connected members having opposed electrodes, and particularly to a connection material containing a thermosetting resin.

  In order to connect between connected members having opposing electrodes, a connecting material mainly composed of a thermosetting resin is used. For example, LCD (liquid crystal display) includes connection of an ITO (Indium Tin Oxide) film on a glass substrate and a TCP (Tape Carrier Package), connection of an ITO film and a driver IC, and the like. Further, as a technique for mounting a semiconductor such as an IC or LSI on a printed board, there is a method of directly mounting a semiconductor chip such as a bare chip on a board with a connecting material. The connection of these members to be connected is made by connecting with a connecting material in a state where a large number of electrodes provided at opposing positions of the chip and the substrate are opposed to each other, so that electrical connection and mechanical fixation are simultaneously obtained. It is.

  As such a connection material, a thermosetting resin is used as a main component, and a connection material is interposed between connected members such as a chip and a substrate, and pressure is applied from both sides with opposing electrodes facing each other. The connection is established by heating and curing the resin. Mechanical fixation between a chip and a member to be connected such as a substrate is performed by a resin adhesion (adhesion) force, and electrodes are electrically connected by pressing the contacts together by resin adhesion. In this case, there are a case where the conductive particles are dispersed in the connecting material to obtain electrical connection by interposing the conductive particles between the electrodes, and a case where electrical connection is obtained by bringing the electrodes into direct contact with each other.

  2. Description of the Related Art In recent years, a reduction in adhesive strength due to a decrease in connection area in a connection between a semiconductor chip and a substrate or between a TCP and ITO has become a problem due to market demands for miniaturization, mainly for portable electronic devices. In addition, it has been studied to mount a driver IC or the like on a flexible printed circuit board (FPC), and it is necessary to increase the bonding strength (peeling strength) of the connection material. In particular, a polyimide resin film is used for FPC, but an adhesive material exhibiting excellent adhesion to such a polyimide resin film has not been known.

  In general, in order to increase the adhesive strength, a technique for softening the bulk of the adhesive and improving the toughness parameter is known, but in this case, the glass transition temperature (hereinafter sometimes referred to as Tg) decreases, Or the phenomenon in which an elasticity modulus falls significantly occurs. The adhesive strength can be expected to be improved by such treatment, but it is difficult to ensure electrical connection under various conditions. For example, it is known that the electrical resistance increases at the connection portion as the adhesive strength decreases at high temperature and high humidity aging, and it is also important how to suppress this phenomenon.

  The problems of the present invention are that the adhesive strength and electrical connection reliability are high, and even when a polyimide resin film is connected, it is possible to effectively perform mechanical fixation and electrical connection, and even when used under high temperature and high humidity. It is to obtain a connection material that does not reduce the reliability of connection.

The present invention is the following connecting material.
(1) A connecting material for connecting a connected member having opposing electrodes,
40 to 70% by weight of thermosetting resin,
10 to 30% by weight of a thermoplastic resin having a glass transition temperature exceeding 50 ° C.,
An adhesive component containing a thermoplastic resin having a glass transition temperature of 30 ° C. or less and / or an elastomer fine particle of 5 to 30% by weight of a crosslinked rubber having a glass transition temperature of 30 ° C. or less and an average particle size of 30 to 300 nm,
The elastic modulus (DMA method) at 30 ° C. after curing is 1.8 to 2.1 GPa,
The glass transition temperature represented by the temperature of the highest peak of tan δ when measuring the elastic modulus is 130 to 140 ° C.,
Tensile elongation (JISK7161) is 3.6 to 7.2%,
High adhesive strength and electrical connection reliability
Even when connecting polyimide resin film, it can effectively perform mechanical fixation and electrical connection,
A connection material that does not deteriorate the electrical connection reliability even when used under high temperature and high humidity.
(2) The connection material according to the above (1), which contains 0 to 40% by volume of conductive particles with respect to the adhesive component.

  In the present invention, the members to be connected are all the electrodes facing each other, particularly members having a large number of electrodes. Among them, a large number of electrodes are provided in a narrow area, such as LCD driver IC and TCP, or a semiconductor chip such as a memory or ASIC, and it is suitable for connection between electrodes of a connected member with a narrow electrode pitch, width and interval. ing. In many cases, a substrate is connected to a member to be connected such as a semiconductor chip as described above, but the connection material of the present invention is mounted even when a semiconductor chip or the like is directly mounted on a printed circuit board or via an interposer or the like. It is also applicable to cases. Examples of the substrate include a substrate made of an arbitrary material such as a glass / epoxy substrate, a resin substrate, a glass substrate, and a flexible resin substrate. Although the polyimide resin film has poor adhesiveness in terms of material, the connection material of the present invention can be bonded even with such a polyimide resin film, and electrical connection reliability can be obtained. A material other than polyimide can also be adhered, and in this case, it is possible to obtain adhesion and electrical connection reliability superior to those of general connection materials.

The connection material of the present invention includes an adhesive component containing a thermosetting resin, the connection material is interposed between the members to be connected, pressed from both sides to press and contact the opposite electrodes, and the connection material is contacted with the electrode. It is configured to be electrically connected and mechanically fixed by being cured and bonded in a collected state in a non-existing portion. The electrodes may be brought into direct contact or may be brought into contact in the presence of conductive particles. When the area of the protruding portion of the electrode is small (for example, 1000 μm ² or less) like a stud bump, it can be brought into direct contact, but when the electrode area is large, it is preferable that conductive particles are present. In order to make the conductive particles exist, the conductive particles are blended in the connecting material.

As the main resin of the thermosetting resin used for the adhesive component of the connection material of the present invention, epoxy resin, urethane resin, phenol resin, hydroxyl group-containing polyester resin, hydroxyl group-containing acrylic resin, etc. are used under heating or UV. A resin that cures under light irradiation such as the above can be used without limitation, but an epoxy resin is particularly preferred from the balance of curing temperature, time, storage stability and the like.
As the epoxy resin, a bisphenol type epoxy resin, an epoxy novolac resin, an epoxy compound having two or more oxirane groups in the molecule, and the like can be used. Commercially available products can be used as they are for these resins.

  The main resin of the above thermosetting resin can generally perform a curing reaction when used in combination with a curing agent, but omit the curing agent when a functional group contributing to the curing reaction is bonded to the main resin. Can do. As the curing agent, there can be used imidazole, amine, acid anhydride, hydrazide, dicyandiamide, modified products thereof, and the like, which undergo a curing reaction by reacting with the main resin by heating, light irradiation or the like, and may be commercially available. As such a curing agent, a latent curing agent is preferable.

  The latent curing agent does not undergo a curing reaction during production, storage at room temperature, and drying at a relatively low temperature (40 to 100 ° C.), but undergoes a curing reaction by heating and pressing at the curing temperature (thermocompression bonding) or irradiation with light such as UV. It is a curing agent. As such a latent curing agent, those obtained by encapsulating the above-mentioned curing agent components such as imidazole and amine are particularly preferable, and commercially available products can be used as they are. In the case of thermal activity, the curing start temperature is preferably 80 to 150 ° C.

The connection material of the present invention includes such a thermosetting resin, a thermoplastic resin having a glass transition temperature exceeding 50 ° C., a thermoplastic resin having a glass transition temperature of 30 ° C. or less, and / or a glass transition temperature of 30 ° C. Hereinafter, an adhesive component containing fine elastomer particles made of a crosslinked rubber having an average particle size of 30 to 300 nm is included.
As the thermoplastic resin, a resin having a Tg of 30 ° C. or lower and rubber elasticity at room temperature can be used, and examples thereof include an acrylic resin and a polyester resin.

As the fine elastomer particles, natural or synthetic rubber fine particles having a Tg of 30 ° C. or less and rubber elasticity at room temperature can be used. For example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene Examples thereof include rubber (SBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and the like.
These rubbers cross-linked rubber is Ru is used. The average particle size of the elastomer fine particles is 30 to 300 nm, preferably 50 to 200 nm. Commercially available products of these elastomer fine particles can be used as they are.

In the present invention blended thermoplastic polymeric material Tg purposes is more than 50 ° C. to impart coatability or film forming the connecting material to the adhesive component. As such a thermoplastic polymer material, a phenoxy resin, a polyester resin, an acrylic resin, or the like can be used.
In addition, additives such as a surfactant, a coupling agent, and an anti-aging agent can be added to the adhesive component of the present invention.

  In the present invention, it is not necessary to use conductive particles in addition to the adhesive component described above. However, when used, conductive coating in which metal particles such as solder, nickel, and polymer core material particles are coated with a conductive material by plating or the like. Particles or insulating coated conductive particles obtained by coating these conductive particles with an insulating resin can be used. These conductive particles have an average particle diameter of 1 to 20 μm, preferably 3 to 10 μm.

In connecting material of the present invention, a 4 0-70 wt% adhesive component is a thermosetting resin, a thermoplastic resin Tg is higher than 50 ° C. 1 0 to 30 wt%, Tg is 3 0 ° C. or less of the thermoplastic resin And / or 5-30% by weight of fine elastomer particles and 0-10% by weight of other additives, preferably 0-5% by weight. The conductive particles can be blended in an amount of 0 to 40% by volume, preferably 0 to 30% by volume, based on these adhesive components.

The connecting material of the present invention can be a product in the form of a paste or film. In the case of making a paste, it is possible to make a paste without a solvent by selecting each of the above components, but in general, each component can be dissolved or dispersed in a solvent to make a paste. As the solvent, solvents such as alcohols, ketones, esters, ethers, phenols, acetals, nitrogen-containing hydrocarbons can be used, and examples thereof include toluene, MEK, ethyl acetate, cellosolve acetate and the like. The usage-amount of a solvent is about 20 to 40 weight% with respect to the resin component.
When forming into a film form, it can shape | mold by apply | coating said paste on a peeling sheet in a film form, and volatilizing a solvent.

The connecting material of the present invention has the above-mentioned components so that the elastic modulus at 30 ° C. after curing is 1.8 to 2.1 GPa, Tg is 130 to 140 ° C., and tensile elongation is 3.6 to 7.2 %. Choose the type and quantity.
The measuring method for each of the above characteristics is as follows.
Modulus: DMA method Tg: highest peak tensile elongation temperature and Tg of the tanδ of the elastic modulus upon measurement: JIS K7161

  The connecting material of the present invention is connected by pressing and heating from both sides of the connected member between the connected members having opposing electrodes, for example, between the substrate and the semiconductor chip, and curing the resin. I do. When the connection material is in a paste form, the connection material is applied to the connection region including the electrode of the connected member, and after other or without drying, another connected member is stacked and pressure-bonded and cured. When the connecting material is in the form of a film, the connecting material is interposed between the members to be connected, and pressurization, heating and curing are performed. Curing can be carried out by irradiation with light such as UV in addition to heating.

  In the above connection step, when the connection material is heated and melted and pressed in a state where the connection material is interposed between the connected members, the connection material flows from the opposite portion of the electrode to the portion without the electrode, and the electrode portion Crimp. When conductive particles are included, the conductive particles remain between the electrodes and come into contact between the electrodes. The adhesive component that has flowed to the portion where there is no electrode is cured at that portion and adheres between the connected members. Thereby, the electrical connection between electrodes and the mechanical fixation between members are performed. By using the connection material of the present invention, mechanical fixation and electrical connection are satisfactorily performed even when the area and interval of the electrodes are narrow, or even when a polyimide resin film is used like FPC. In the case of a connected member other than polyimide, the adhesive strength is increased.

  For example, when mounting a semiconductor chip or the like on a substrate, the semiconductor chip or the like as one connected member is mounted by connecting it to the substrate or the like as the other connected member, and then used in a high temperature and high humidity environment. However, by using the connection material of the present invention, electrical connection reliability is obtained over a long period of time, and no conduction failure between the electrodes occurs.

According to the present invention, a thermosetting resin as a main component, a thermoplastic resin having a glass transition temperature exceeding 50 ° C, a thermoplastic resin having a glass transition temperature of 30 ° C or less and / or a glass transition temperature of 30 ° C or less, Adhesive component containing a specific amount of elastomer fine particles composed of crosslinked rubber having an average particle size of 30 to 300 nm is included, and a specific elastic modulus, Tg, and tensile elongation are obtained, so that adhesive strength and electrical connection reliability are achieved. Therefore, even when a polyimide resin film is connected, it is possible to effectively perform fixing and electrical connection, and it is possible to obtain a connection material whose electrical connection reliability does not deteriorate even when used under high temperature and high humidity.

  Hereinafter, embodiments of the present invention will be described by way of examples.

Examples 1-5, Comparative Examples 1-3
(Preparation of connecting material)
It consists of epoxy resin (Dainippon Ink Chemical Co., Ltd., 4032D, trade name) as a thermosetting resin, imidazole series curing agent (Asahi Kasei Co., Ltd., HX-3941HP, trade name) as a curing agent, and a crosslinked rubber having a Tg of 30 ° C. or less. Polybutadiene rubber fine particles (manufactured by Kuraray Co., Ltd., average particle size of 80 nm) as elastomer fine particles, acrylic resin (SG80, trade name, Tg: -25 ° C., manufactured by Fujikura Kasei Co., Ltd.) as a thermoplastic resin having a Tg of 30 ° C. or less, and heat exceeding Tg 50 ° C. The composition shown in Table 1 is a phenoxy resin (manufactured by Tohto Kasei Co., Ltd., YP50, trade name, Tg: 80 ° C.) as a plastic resin, and conductive coated particles (manufactured by Nippon Chemical Industry Co., Ltd., EH20GNR, trade name, particle size 5 μm) as conductive particles. And dissolved in toluene as a solvent to obtain a paste-like connecting material. This is coated on a release film made of PET (polyethylene terephthalate) that has been subjected to a release treatment so as to have a dry film thickness of 40 μm, and left in an oven with circulating air at 80 ° C. for 5 minutes to form a film-like connecting material. Obtained.

(Physical property test)
The elastic modulus was measured by cutting an uncured connection material into a size of 6 cm × 0.2 cm, curing at 180 ° C. for 15 minutes, and then peeling off from the PET film as a sample. Vibron DDV01FP (trade name) manufactured by Orientec Co., Ltd. was used as a tester, and measurement was performed at a distance between chucks of 5 cm, a measurement frequency of 11 Hz, and a heating rate of 3 ° C./min.
The peak temperature of tan δ at the time of measuring the elastic modulus was defined as Tg.

(Tensile test)
As a measuring method of the tensile test, an uncured connection material was cut into a size of 1 cm × 15 cm using a cutter knife, cured for 15 minutes in a 180 ° C. hot air circulation oven, and then peeled off from the PET film to obtain a sample. Using a Shimadzu autograph AGS-H and a video extensometer DVE-200 as the tensile tester, the tensile elongation was measured at a tensile speed of 1 mm / min, a distance between chucks of 10 cm, a distance between marked lines of 5 cm, and a measurement temperature of 23 ° C. did.

(Connection test)
An IC chip (material: silicon, dimension: 6 mm × 3 mm, thickness: 0.4 mmt, bump: gold plating, bump thickness: 20 μmt, number of bumps: 272 pins, pitch: 85 μm) is connected to the FPC through the film-like connecting material. Connected to the substrate. The FPC board is obtained by forming a conductor pattern (copper 12 μm, nickel-gold plating) corresponding to a bump of an IC chip on a 25 μm-thick polyimide film (Toray Industries, Kapton, trade name, dimensions: 40 mm × 40 mm). . The IC chip was stacked on the substrate via a connecting material so that the bump and the conductor pattern faced each other, and connected by heating and pressing at 190 ° C. × 10 seconds × thrust 4 kgf.

About the said connection body, 90 degree peel strength was measured and it was set as connection strength.
Regarding the electrical connection reliability, the connection resistance after being left for 1000 hours in an initial state and an 85 ° C. and 85% RH atmosphere was measured by a four-terminal method, and displayed as an average value at 40 measurement terminals.
The results are shown in Table 1.

＊１：接着剤成分に対する容量％

* 1: Volume% relative to adhesive component

  From the result of Table 1, the connection material of Examples 1-5 showed the adhesiveness outstanding also with respect to the polyimide resin film, and the result excellent also about the electrical connection reliability was obtained. On the other hand, it can be seen that Comparative Examples 1 to 3 whose characteristics do not satisfy the scope of the present invention are inferior in connection strength and in terms of electrical connectivity.

Claims (2)

A connection material for connecting a member to be connected having opposing electrodes,
40 to 70% by weight of thermosetting resin,
10 to 30% by weight of a thermoplastic resin having a glass transition temperature exceeding 50 ° C.,
An adhesive component containing a thermoplastic resin having a glass transition temperature of 30 ° C. or less and / or an elastomer fine particle of 5 to 30% by weight of a crosslinked rubber having a glass transition temperature of 30 ° C. or less and an average particle size of 30 to 300 nm,
The elastic modulus (DMA method) at 30 ° C. after curing is 1.8 to 2.1 GPa,
The glass transition temperature represented by the temperature of the highest peak of tan δ when measuring the elastic modulus is 130 to 140 ° C.,
Tensile elongation (JISK7161) is 3.6 to 7.2%,
High adhesive strength and electrical connection reliability
Even when connecting polyimide resin film, it can effectively perform mechanical fixation and electrical connection,
A connection material that does not deteriorate the electrical connection reliability even when used under high temperature and high humidity.   The connection material according to claim 1, comprising 0 to 40% by volume of conductive particles with respect to the adhesive component.