JP5621401B2 - Method for manufacturing connection structure - Google Patents

Description

  The present invention relates to a method for manufacturing a connection structure in which electrodes of a light-transmitting wiring board and bumps of a semiconductor chip are anisotropically conductively connected using an anisotropic conductive film.

  A COG (Chip on Glass) mounting body in which an IC chip is mounted on a transparent glass substrate, for example, a liquid crystal panel has been put into practical use. In such a liquid crystal panel, a backlight is provided outside the transparent glass substrate, and light from the backlight is incident on the transparent glass substrate. For this reason, light is necessarily irradiated to the IC chip mounted on the glass substrate. For this reason, there is a concern that the semiconductor chip malfunctions due to photoexcitation of electrons in the silicon portion of the semiconductor chip, resulting in display defects such as garbled display or missing display.

  In order to eliminate such concerns, a light-shielding anisotropic conductive film provided with light-shielding properties by blending light-absorbing carbon particles as an anisotropic conductive film used when mounting an IC chip on a glass substrate It has been proposed to use

Japanese Unexamined Patent Publication No. 2000-1223639

  However, in the case of the anisotropic conductive film to which the light shielding property is imparted by the carbon particles of Patent Document 1, there is a problem that the relative dielectric constant of the entire film increases due to the blending of the carbon particles. When such an anisotropic conductive film having an increased relative dielectric constant is applied to high-density mounting, there is a concern that noise may occur between adjacent wirings that are very close to each other. Moreover, since such a light-shielding anisotropic conductive film is light-shielding before the anisotropic conductive connection, it is possible to temporarily attach the anisotropic conductive film to the glass substrate or to the temporarily attached anisotropic conductive film. When the IC chip is temporarily installed, it is difficult to visually recognize the electrodes and alignment marks on the glass substrate, and as a result, alignment between the glass substrate and the IC chip is difficult.

  An object of the present invention is to solve the conventional problems as described above, and to perform alignment between a light-transmitting wiring board such as a glass substrate and a semiconductor element such as an IC chip at a high level. It is possible to manufacture a connection structure using an anisotropic conductive film that has a high light-shielding property so that light from a light-transmitting wiring board is not incident on a semiconductor element.

  The present inventor can perform alignment through the anisotropic conductive film before the anisotropic conductive connection treatment, but the light transmission is reduced at the same time or after the anisotropic conductive connection treatment, and the light shielding property is reduced. Under the assumption that the above-mentioned object can be achieved by using the anisotropic conductive film shown, the components of the anisotropic conductive film were investigated, and a styrene block copolymer was added to the thermosetting epoxy resin composition. It has been found that the problem can be solved by blending a specific amount of the present invention, and the present invention has been completed.

That is, the present invention is a method for manufacturing a connection structure in which electrodes of a light-transmitting wiring board and bumps of a semiconductor element are anisotropically conductively connected using an anisotropic conductive film,
The anisotropic conductive film formed by dispersing conductive particles in a thermosetting epoxy resin composition containing an epoxy compound, an epoxy curing agent, a film-forming polymer, and a silane coupling agent The thermosetting epoxy resin composition further contains a styrenic block copolymer in a proportion of 5 to 20% by mass in the anisotropic conductive film,
Temporarily sticking the anisotropic conductive film to the electrode of the light transmissive wiring board,
Temporarily installing the semiconductor element while aligning the anisotropic conductive film on the anisotropic conductive film temporarily attached,
Anisotropic conductive connection treatment is applied to the electrode of the light-transmitting wiring board through the anisotropic conductive film by heating and pressurizing the temporarily installed semiconductor element, and anisotropic at the same time or after the anisotropic conductive connection treatment A manufacturing method for reducing the light transmittance of a conductive film and a connection structure obtained by the manufacturing method are provided.

  In the method for producing a connection structure of the present invention, a thermosetting epoxy resin composition containing an epoxy compound, an epoxy curing agent, a film-forming polymer, and a silane coupling agent is used as the anisotropic conductive film. The film is formed by dispersing conductive particles, and the thermosetting epoxy resin composition further contains a styrene block copolymer in a proportion of 5 to 20% by mass in the anisotropic conductive film. Use what you have. Since this anisotropic conductive film is light transmissive before anisotropic conductive connection, the semiconductor element can be aligned with the light transmissive wiring board through the anisotropic conductive film. At the same time as or after the connection process, the light transmittance is lowered, so that the light incident on the semiconductor element can be prevented.

  The reason why the light transmittance of the anisotropic conductive film decreases at the same time as or after the anisotropic conductive connection treatment is due to the thermal expansion of the film, IC, and glass substrate due to the curing reaction during the anisotropic conductive connection. This is thought to be because the phase separation of the styrenic block copolymer proceeds in the thermosetting epoxy resin composition in the film, causing light scattering and light absorption due to the resulting phase separation structure. .

  Actually, in the method for manufacturing a connection structure according to the present invention, when the anisotropic conductive connection is performed under the condition of high temperature / high pressure, higher light shielding property can be exhibited. In other words, when this anisotropic conductive film is applied to high-temperature mounting (for example, mounting at 210 to 240 ° C.), the curing reaction proceeds rapidly, and the cross-linking density of the phase separation structure increases, When applied to high-pressure mounting (for example, mounting at 80 to 140 MPa), the mixing of the constituent components of the film is accelerated, and the phase separation structure domains are promoted to be refined. This is probably because the light scattering / light absorption efficiency of the anisotropic conductive film is improved.

  An object of the manufacturing method of the present invention is a connection structure in which electrodes of a light-transmitting wiring board and bumps of a semiconductor element are anisotropically conductively connected using an anisotropic conductive film. First, the configuration of the connection structure will be described, and then the manufacturing method will be described in detail.

<Configuration of connection structure>
The light-transmitting wiring board constituting the connection structure is formed of a light-transmitting conductive material such as indium-tin composite oxide on a light-transmitting glass substrate, a light-transmitting quartz substrate, and a light-transmitting plastic substrate. The wiring board which has the wiring and electrode which were formed from wiring, an electrode, metal materials, such as aluminum and copper, can be mentioned.

  As semiconductor elements, semiconductor electronic parts such as IC chips called so-called integrated circuit elements and optical elements such as LEDs can be widely used. As the bump, a gold stud bump, a solder bump, or the like can be applied.

  The anisotropic conductive film was formed by dispersing conductive particles in a thermosetting epoxy resin composition containing an epoxy compound, an epoxy curing agent, a film-forming polymer, and a silane coupling agent. A film that is a thermosetting epoxy resin composition and further contains a styrenic block copolymer is used. Content in the anisotropic conductive film of a styrene-type block copolymer is 5-20 mass%, Preferably it is 8-15 mass%. It is because sufficient light-shielding property cannot be acquired as it is less than 5 mass%, and when it exceeds 20 mass%, the connection reliability of an anisotropic conductive film will fall large.

  The meaning of light transmittance of the anisotropic conductive film before the anisotropic conductive connection treatment and the anisotropic conductive film after the anisotropic conductive connection treatment is defined as described below.

  The light transmittance before anisotropic conductive connection treatment of an anisotropic conductive film having a film thickness of 25 μm with respect to light having a light transmission wavelength of 1100 nm is different between two transparent glass substrates having a thickness of 0.7 mm and a thickness of 0.5 mm. It is a numerical value measured with a spectrophotometer when the anisotropic conductive film before the anisotropic conductive connection treatment is sandwiched. The numerical value is preferably 60% or more, and more preferably 70% or more, because if the value is too small, accurate alignment of the semiconductor elements is hindered. On the other hand, the light transmittance of the anisotropic conductive film after the anisotropic conductive connection treatment is 200 ° C. with an anisotropic conductive film sandwiched between two transparent glass substrates having a thickness of 0.7 mm and a thickness of 0.5 mm. This is a numerical value measured with a spectrophotometer when heated and pressurized for 10 seconds under the condition of 60 Pa. If the numerical value is too large, the light shielding property is insufficient and causes a malfunction of the semiconductor element. Therefore, it is preferably 50% or less, more preferably 40% or less.

  As described above, the thermosetting epoxy resin composition constituting the anisotropic conductive film contains an epoxy compound, an epoxy curing agent, a film-forming polymer, a silane coupling agent, and a styrene block copolymer.

  Examples of the epoxy compound include a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a novolac type epoxy resin, a modified epoxy resin thereof, an alicyclic epoxy resin, and the like. it can. In the present invention, use of a liquid epoxy compound having a viscosity (25 ° C.) of 2 to 200 Pa · s according to JIS K7117-1 can realize good transferability to the panel and good connection reliability after curing. This is preferable.

  If the amount of such a low molecular weight liquid epoxy compound in the thermosetting epoxy resin composition is too small, the transfer property to the adherend of the anisotropic conductive film before curing or the anisotropic property after curing Adhesiveness of the conductive conductive film to the adherend becomes insufficient, and if it is too much, it may be due to poor application of the thermosetting epoxy resin composition at the time of anisotropic conductive film creation or the reel state of the anisotropic conductive film. The thermosetting epoxy resin composition tends to become a cause of occurrence of a problem when stored, and is preferably 15 to 65% by mass, more preferably 30 to 50% by mass.

  Examples of epoxy curing agents include anionic curing agents such as polyamines and imidazoles, cationic curing agents such as sulfonium salts, and latent curing agents such as phenolic curing agents. In particular, a cationic curing agent can be preferably used from the viewpoint of low temperature and rapid curing.

  If the amount of the epoxy curing agent in the thermosetting epoxy resin composition is too small, curing of the anisotropic conductive film will be poor, and if too large, the product life of the anisotropic conductive film tends to decrease. In the thermosetting epoxy resin composition, preferably 1 to 20% by mass, more preferably 3 to 10% by mass.

  Examples of the film-forming polymer include phenoxy resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, urethane resin, butadiene resin, polyimide resin, polyamide resin, polyolefin resin, and the like. be able to. Among these, a phenoxy resin can be preferably used from the viewpoint of film forming property, workability, and connection reliability.

  If the blending amount of the film-forming polymer in the thermosetting epoxy resin composition is too small, the film-forming ability will decrease, and if it is too large, the resin composition will have poor solubility and poor coating. Since it exists, Preferably it is 15-55 mass%, More preferably, it is 30-40 mass%.

  Examples of the silane coupling agent include an epoxy silane coupling agent and an acrylic silane coupling agent. These silane coupling agents are mainly alkoxysilane derivatives.

  If the blending amount of the silane coupling agent in the thermosetting epoxy resin composition is too small, the adhesion between the anisotropic conductive film and the glass substrate is lowered, and if it is too large, the adverse effect due to hydrolysis of the silane coupling agent is caused. Since there exists a tendency to become remarkable, Preferably it is 0.5-3 mass%, More preferably, it is 1-2 mass%.

  Styrenic block copolymers are AB type or ABA type block copolymers, such as styrene-acrylic block copolymers, styrene-butadiene block copolymers, and styrene-vinyl acetate block copolymers. Examples thereof include a styrene-ethylene-butylene block copolymer, a styrene-ethylene-propylene block copolymer, a styrene-ethylene-styrene block copolymer, and a styrene-isoprene block copolymer. Among these styrenic block copolymers, those having a styrene copolymer composition ratio of 30 wt% or more are preferable from the viewpoint of the balance between dispersibility and viscosity. In addition, an epoxy group or a carboxyl group may be introduced into these styrenic block copolymers in an arbitrary range, and a commercially available product may be used as such a block copolymer.

  The conductive particles constituting the anisotropic conductive film can be appropriately selected from those conventionally used for anisotropic conductive adhesives. For example, metal particles such as nickel, cobalt, silver, copper, gold, and palladium, metal-coated resin particles, and the like can be used, and two or more of these can be used in combination. These particle sizes are usually 1-10 μm.

  If the blending amount of the conductive particles in the anisotropic conductive film is too small, connection reliability becomes poor, and if it is too large, there is a tendency to cause a short-circuit, so 5 to 50% by mass, more preferably It is 10-35 mass%.

<Manufacture of connection structure>
First, an anisotropic conductive film composed of the above-described constituent components, which has an optically conductive film whose optical transparency is reduced by the anisotropic conductive connection treatment, is temporarily attached to the electrode of the optically transparent wiring board. . In addition, as the temporary pasting operation / condition, a known method / condition may be employed.

  Next, the semiconductor element is temporarily placed on the temporarily attached anisotropic conductive film while being aligned through the anisotropic conductive film. At the time of this temporary installation, since this anisotropic conductive film is before the anisotropic conductive connection treatment, the light transmission is not lowered. Therefore, the semiconductor element can be easily aligned at a predetermined position on the light-transmitting wiring board using the alignment mark or electrode of the light-transmitting wiring board as a mark. Also, a known method / condition can be adopted as the temporary installation operation / condition.

  Next, an anisotropic conductive connection process is performed to cure the anisotropic conductive film by heating and pressurizing the temporarily installed semiconductor element with a heat and pressure bonder or the like. At the same time as or after this anisotropic conductive connection treatment, the light transmittance of the anisotropic conductive film decreases. Thereby, the connection structure by which the electrode of a light-transmitting wiring board and the bump of a semiconductor element are anisotropically conductive-connected using an anisotropic conductive film can be obtained.

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

Reference example (Preparation of styrenic block copolymer)
In a glass reactor equipped with a thermometer, a nitrogen introduction tube, a stirrer and a condenser, 300 parts by mass of water, 15 parts by mass of a 1% aqueous solution of partially saponified polyvinyl alcohol (GOHSENOL KH-17, Nippon Synthetic Chemical Industry Co., Ltd.) And 15 parts by mass of a 10% dispersion of hydroxyapatite (Super Tight 10, Nippon Chemical Industry Co., Ltd.) were added and mixed. To this mixed solution, 0.5 part by mass of polymeric peroxide was added and dispersed by stirring for 1 hour at room temperature. To this dispersion, 30 parts by mass of vinyl acetate was added, and polymerization was carried out by stirring at 60 ° C. for 2 hours while introducing nitrogen into the reactor (first stage polymerization).

  After the first stage polymerization, the polymerization mixture was cooled to room temperature, 70 parts by mass of styrene was added to the mixture, and stirring was continued at room temperature for 1 hour. Subsequently, while introducing nitrogen into the reactor, the mixture was further stirred at 80 ° C. for 8 hours, and further stirred at 90 ° C. for 0.5 hour to perform polymerization again (second stage polymerization).

  The obtained mixture was cooled to room temperature, and the target copolymer was obtained as a precipitate. This precipitate was washed with 130 parts by mass of 5% hydrochloric acid, subsequently washed with water, filtered, and dried to obtain a white granular styrenic block copolymer (yield 85%). The composition ratio of styrene and vinyl acetate in this copolymer was 70:30.

Example 1
(Creation of anisotropic conductive film whose light transmittance is reduced by anisotropic conductive connection treatment)
The components of the formulation of Table 1 were uniformly mixed using a stirrer, and the resultant mixture was formed into a film having a thickness of 25 μm by a bar coater to prepare an anisotropic conductive film.

(Measurement of light transmittance of anisotropic conductive film (ACF))
The obtained anisotropic conductive film was sandwiched between two transparent glass substrates having a thickness of 0.7 mm and a thickness of 0.5 mm, and using a spectrophotometer (MCPD-100, manufactured by Otsuka Electronics Co., Ltd.) The light transmittance of light having a wavelength of 1100 nm was measured. Then, after heat-pressing on the crimping | compression-bonding conditions of Table 2 corresponded to anisotropic conductive connection conditions and standing to cool to room temperature, the light transmittance was measured again. Table 2 shows the results of light transmittance before and after heating and pressing of the anisotropic conductive film.

(Manufacture of connection structures and evaluation of IC chip visibility (transparency and light shielding))
On the electrode of the liquid crystal glass panel, an anisotropic conductive film having a width of 3 mm was temporarily pasted at 60 ° C. using a temporary pasting apparatus. Next, a 2 mm × 20 mm IC chip provided with gold bumps on the anisotropic conductive film was temporarily installed at 50 ° C. from the bump side with the alignment mark of the liquid crystal panel as a mark through the anisotropic conductive film. When the IC chip was observed through the liquid crystal glass panel side, the characters on the face of the temporarily installed IC chip could be visually recognized. The degree of visual recognition before this crimping was evaluated according to the following criteria, and the results obtained are shown in Table 2.

(Method of verification)
Using a microscope (OLYMPUS MX50), a CCD camera (FLOWEL ADP210), and image processing software (FLOWEL Filing System), the incident light was kept constant, and the difference was confirmed by displaying the brightness of the software. At that time, the luminance distribution was displayed in 256 gradations. The smaller the value is, the darker the image is, that is, the less reflected light is, and the light is scattered and absorbed.

Rank criteria
AA: R, G, B all 200 or more A: R, G, B all 100 or more and less than 200 B: R, G, B all 50 or more and less than 100 C: R, G, B all less than 50

  The connection structure in which the bumps of the IC chip are anisotropically conductively connected to the electrodes of the liquid crystal glass panel by heating and pressing the temporarily installed IC chip using a heating bonder under the pressure bonding conditions shown in Table 2. Obtained. From the liquid crystal glass panel side, the IC chip after pressure bonding was observed through the cured anisotropic conductive film, verified in the same manner as the above verification method, and evaluated according to the following criteria. The obtained results are shown in Table 2.

Rank Criteria AA: R, G, B all less than 50 A: R, G, B all 50 or more and less than 100 B: R, G, B all 100 or more and less than 200 C: R, G, B all 200 or more

(Evaluation of connection reliability after initial and accelerated test (high temperature and high humidity environment storage) of connection structure)
The connection resistance (initial) of the connection structure immediately after manufacturing and the connection reliability after being left in a high temperature and high humidity environment (85 ° C, 85% RH) for 500 hours were measured for the conduction resistance value by the 4-terminal method. Evaluation was made according to the following criteria. The obtained results are shown in Table 2.

Rank criteria
A: 0 to less than 10Ω B: 10 to less than 50Ω C: 50Ω or more

(Insulation evaluation of connection structure)
The insulation resistance between adjacent terminals of the connection structure immediately after manufacture was measured according to the following criteria by measuring the insulation resistance value. The obtained results are shown in Table 2.

Rank Criteria A: 1.0 × 10 ⁹ Ω or more B: 1.0 × 10 ⁶ Ω or more and less than 1.0 × 10 ⁹ Ω C: Less than 1.0 × 10 ⁶ Ω

Example 2
An anisotropic conductive film was prepared in the same manner as in Example 1 except that the blending amount of the styrene block copolymer was changed from 5 parts by mass to 10 parts by mass, and a connection structure was prepared and evaluated in the same manner. . The obtained results are shown in Table 2.

Example 3
An anisotropic conductive film was prepared in the same manner as in Example 1 except that the blending amount of the styrene block copolymer was changed from 5 parts by mass to 20 parts by mass, and a connection structure was prepared and evaluated in the same manner. . The obtained results are shown in Table 2.

Example 4
An anisotropic conductive film was prepared in the same manner as in Example 1 except that the blending amount of the styrene block copolymer was changed from 5 parts by mass to 10 parts by mass and the pressure bonding temperature was changed from 200 ° C to 220 ° C. Then, a connection structure was created and evaluated in the same manner. The obtained results are shown in Table 2.

Example 5
An anisotropic conductive film was prepared in the same manner as in Example 1 except that the blending amount of the styrenic block copolymer was changed from 5 parts by mass to 10 parts by mass and the pressure bonding pressure was changed from 60 MPa to 80 MPa. A connection structure was created and evaluated in the same manner. The obtained results are shown in Table 2.

Example 6
Example 1 except that the blending amount of the styrenic block copolymer is changed from 5 parts by weight to 10 parts by weight, the pressure bonding temperature is changed from 200 ° C. to 190 ° C., and the pressure bonding pressure is changed from 60 MPa to 40 MPa. Similarly, an anisotropic conductive film was prepared, a connection structure was prepared, and evaluated in the same manner. The obtained results are shown in Table 2.

Comparative Example 1
An anisotropic conductive film was prepared in the same manner as in Example 1 except that the blending amount of the styrene block copolymer was changed from 5 parts by mass to 1 part by mass, and a connection structure was prepared and evaluated in the same manner. . The obtained results are shown in Table 2.

Comparative Example 2
An anisotropic conductive film was prepared in the same manner as in Example 1 except that the blending amount of the styrene block copolymer was changed from 5 parts by weight to 25 parts by weight, and a connection structure was prepared and evaluated in the same manner. . The obtained results are shown in Table 2.

Comparative Example 3
An anisotropic conductive film was prepared in the same manner as in Example 1 except that 10 parts by mass of carbon black was used instead of the styrene block copolymer, and a connection structure was prepared and evaluated in the same manner. The obtained results are shown in Table 2.

  As can be seen from Table 2, the anisotropic conductive films of Examples 1 to 6 containing the predetermined styrenic block copolymer in an amount of 5 to 20% by mass are anisotropic even when the pressure bonding conditions are changed. After the conductive conductive connection treatment, good light shielding properties were exhibited. Moreover, the initial connection reliability and the connection reliability after the acceleration test were excellent, and the insulation between adjacent terminals was also excellent.

  On the other hand, the anisotropic conductive film of Comparative Example 1 containing an excessively small amount of the predetermined styrene-based block copolymer at 1% by mass did not have sufficient light-shielding properties after pressure bonding. In addition, the anisotropic conductive film of Comparative Example 2 containing a predetermined styrene block copolymer so as to have an excessively large amount of 25% by mass has a problem in connection reliability and cannot be used in practice. In addition, the anisotropic conductive film of Comparative Example 3 using conventional carbon black as a light shielding material was originally poor in transparency before pressure bonding, and accurate alignment could not be expected.

  In the manufacturing method of the connection structure according to the present invention, the anisotropic conductive film can be aligned through the anisotropic conductive film before the anisotropic conductive connection. An anisotropic conductive film in which the resistance is lowered is used. Therefore, it is possible to align the IC with respect to the glass substrate before the anisotropic conductive process, and it is possible to prevent light from entering the IC after the anisotropic conductive connection process. Therefore, the manufacturing method of the present invention is useful for manufacturing a COG package.

Claims (2)

A method of manufacturing a connection structure in which electrodes of a light-transmitting wiring board and bumps of a semiconductor element are anisotropically conductively connected using an anisotropic conductive film,
The anisotropic conductive film formed by dispersing conductive particles in a thermosetting epoxy resin composition containing an epoxy compound, an epoxy curing agent, a film-forming polymer, and a silane coupling agent The thermosetting epoxy resin composition further contains a styrene block copolymer in a proportion of 5 to 20% by mass in the anisotropic conductive film, and has a film thickness of 25 μm with respect to light having a wavelength of 1100 nm. The light transmittance of the anisotropic conductive film is 60% or more before the anisotropic conductive connection treatment, and is 50% or less after the anisotropic conductive connection treatment,
Temporarily sticking the anisotropic conductive film to the electrode of the light transmissive wiring board,
Temporarily installing the semiconductor element while aligning the anisotropic conductive film on the anisotropic conductive film temporarily attached,
Anisotropic conductive connection treatment is applied to the electrode of the light-transmitting wiring board through the anisotropic conductive film by heating and pressurizing the temporarily installed semiconductor element, and anisotropic at the same time or after the anisotropic conductive connection treatment Manufacturing method which reduces the light transmittance of a conductive film.   The production method according to claim 1, wherein a cationic curing agent is used as the epoxy curing agent.