JP4378788B2 - IC chip connection method - Google Patents

Description

【００１９】
評価２
実施例１〜３、比較例１〜２で得られた接続体を用いて、接続抵抗値を評価した。評価方法は、抵抗測定機を用いて、バンプサイズ５０×５０μｍ当たりの接続抵抗値を測定した。また、この接続体を高温高湿中（８５℃８５％ＲＨ）に５００ｈ放置して、接続抵抗値の変化を測定した。
得られた結果を表２に示す。この結果から明らかなように、本発明の接続方法を用いることにより、高い接続信頼性が得られることが分かった。
【００２０】
【表２】

【００２１】
【発明の効果】
本発明によれば、接続時に相対峙する回路基板とＩＣチップのそれぞれを所定の温度で加熱することにより、回路基板の伸び量とＩＣチップの伸び量の差を極小にできることから、反り、クラック等の変形が低減できる接続方法を提供できる。また、接続部への応力集中を緩和できることから接続信頼性の向上が可能である。さらに、接着剤の活性化温度以下で回路基板を加熱することにより、量産性及び接続後の接続信頼性に優れた接続方法を提供できる。
【図面の簡単な説明】
【図１】本発明の一実施例を説明する接続方法の断面模式図。
【図２】本発明の他の実施例を説明する接続方法の断面模式図。
【図３】接続部材の断面模式図。
【図４】接続部材の断面模式図。
【図５】多層接続部材の断面模式図。
【図６】接続部材の粘度の挙動を示す線図。
【符号の説明】
１ 回路基板 ２ ＩＣチップ
３ 接続部材 ４ 圧着ステージ
５ 圧着ヘッド ６ 絶縁性接着剤
７ 導電材料[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a connection method for connecting an IC chip to various circuit boards (an inorganic substrate such as glass or ceramic, an organic substrate such as polyimide or polyester film, a composite material of glass and an organic material, or the like).
[0002]
[Prior art]
In recent years, with the reduction in size and thickness of electronic components, circuits used for these have become higher in density and higher in definition. Since it is difficult to connect such electronic components and fine electrodes with conventional solders, rubber connectors, or the like, connection members having excellent resolution have been frequently used recently.
This connection member is an insulating adhesive that contains a predetermined amount of conductive material such as conductive particles in an insulating adhesive that can be cured for a short time and has a molecular structure with excellent adhesion to an epoxy adhesive. Adhesive is used. There is also known a method of fixing and maintaining the direct contact state between electrodes with an insulating adhesive alone without containing these conductive materials.
When connected using an insulating adhesive containing a predetermined amount of this conductive material, the electrodes of the electronic components are electrically connected to each other through the conductive material. It is used favorably because the phenomenon is unlikely to occur. On the other hand, the method using an insulating adhesive alone has a feature that there is no short circuit between adjacent electrodes due to a conductive material, and high-definition connection is possible.
In the connection method using these connection members, a connection member is provided between the electrode of the electronic component and the substrate circuit, and the electronic component is heated and pressurized using a special jig or the like. For example, in connecting a glass electrode substrate of a liquid crystal panel and an IC chip, first, a connection member is temporarily attached on the glass substrate. Thereafter, the IC chip and the substrate are aligned, and heating and pressurizing means are taken and connected. As a result, both electrodes are electrically connected to each other, and insulation between the adjacent electrodes is imparted, and the glass substrate and the IC chip are bonded and fixed.
[0003]
[Problems to be solved by the invention]
In connecting the glass electrode substrate of the liquid crystal panel and the IC chip in the conventional method, heating from the IC chip side is common. As this heating method, a method using a heating jig (crimp head) such as a metal or ceramic with a built-in heater or hot air heating is generally used. The heating temperature at this time is set to be about 120 to 240 ° C. at which the connecting member undergoes a crosslinking and curing reaction, and is maintained for about 4 to 40 seconds in this state. At this time, since heat is conducted through the IC chip, thermal loss is large, and a temperature difference is generated between the IC chip and the connection member and further the substrate. For this reason, a difference occurs between the extension amount of the IC chip and the extension amount of the substrate, and problems such as a decrease in connection reliability due to stress concentration on the connection portion, warpage, and cracks occur.
[0004]
The present invention has been made in view of such a situation. Heating is performed from both of the circuit board and the IC chip which are opposed to each other, and the difference between the extension amount of the circuit board and the extension amount of the IC chip is minimized. An object of the present invention is to provide a connection method capable of reducing deformation such as cracks and improving connection reliability.
[0005]
[Means for Solving the Problems]
That is, the present invention is, between the connection electrodes of the circuit board and the IC chip, heat by shows an initial flow and a minimum viscosity, the connecting member is subsequently Rineba degree by the curing reaction a thermosetting insulating adhesive to rise In a connection method consisting of electrical connection between electrodes and fixing between parts by heating and pressing between opposed electrodes, the thermosetting insulating adhesive is initially flowed by heat and the lowest A circuit board in which the magnitude of the change in viscosity per unit time when the viscosity rises by the curing reaction is larger than the magnitude of the change in viscosity per unit time until the viscosity is shown. And the IC chip are heated at a predetermined temperature, thereby minimizing the difference between the amount of elongation of the circuit board and the amount of elongation of the IC chip at the time when the connecting member has a minimum viscosity after crimping. Chip method for the connection.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of a connection method for explaining an embodiment of the present invention.
In this connection method, a connection body in which a connection member 3 is provided between the electrodes of the circuit board 1 and the bumps of the IC chip 2 is placed on the pressure-bonding stage 4, and heating and pressure means are taken using the pressure-bonding head 5. It is. As shown in FIG. 2, heating and pressurization may be performed using pressure bonding heads arranged vertically. Although not shown, hot air may be used as a heating source.
Examples of the material of the pressure bonding head 5 include metal and ceramic, and any temperature can be set by a heater provided therewith. Further, the pressure can be arbitrarily set by using air pressure or the like.
Examples of the material of the crimping stage 4 include glass, metal, and ceramic, and any temperature can be set by a heater provided therewith.
[0007]
As shown in FIG. 3, the connecting member is made of the insulating adhesive 6 alone. Or it consists of the insulating adhesive 6 containing the electrically-conductive material 7 as shown in FIG. 4, and this thing has electroconductivity in a pressurization direction. Furthermore, as shown in FIG. 5, a multilayer connection member in which an insulating adhesive 6 ′ is formed on at least one surface of a conductive adhesive layer made of a conductive material 7 and an insulating adhesive 6 may be used. Although not shown, the insulating adhesive may be formed on both surfaces of the conductive adhesive layer.
Examples of conductive materials include metal particles such as Au, Ag, Pt, Ni, Cu, W, Sb, Sn, and solder, carbon, etc., and these conductive particles are used as a core material or non-conductive glass. Alternatively, a core material made of a polymer such as ceramic or plastic may be coated with a conductive layer made of the above material. Furthermore, insulating coating particles formed by coating a conductive material with an insulating layer or insulating particles as a spacer may be used in combination.
[0008]
The particle diameter of the conductive particles is preferably a small particle diameter, preferably 0.5 to 15 μm, and more preferably 2 to 8 μm in order to secure one or more, preferably a large number of particles on the microelectrode. The filling amount of the conductive particles is preferably less than 25% by volume in the insulating adhesive in order to ensure conductivity and insulation with respect to the high-definition circuit electrode.
Insulating adhesives are initially flowable by heat to lower viscosity, and materials that continue to exhibit curability can be widely applied, and these are preferably applied with thermosetting materials because they have excellent heat resistance and moisture resistance after connection. . Among these, epoxy adhesives can be preferably applied because of their characteristics such that they can be cured in a short time, have good connection workability, and have excellent adhesion in terms of molecular structure.
Epoxy adhesives are mainly composed of epoxy resin modified with high molecular weight epoxy, solid epoxy and liquid epoxy, urethane, polyester, acrylic rubber, NBR, nylon, etc., and hardeners, catalysts, coupling agents, fillers The one formed by adding etc. is common.
[0009]
The curing agent is preferably a latent curing agent in order to maintain the storage stability of the connection member. The latent curing agent referred to in the present invention means a material that has coexistence with a reactive resin (for example, epoxy resin) and rapidly cures at a predetermined temperature. As such a latent curing agent, those obtained by microencapsulating various curing agent components are commercially available. Moreover, the activation temperature temperature of an adhesive agent can be represented by the activation temperature in the coexistence of the reactive resin which is a main component of an adhesive agent, and a latent hardener. The activation temperature rises from room temperature (30 ° C) to 250 ° C at 10 ° C / min using DSC (Differential Scanning Calorimeter) with 3 mg of coexisting mixed sample of reactive resin and latent curing agent. The peak temperature indicates the maximum amount of heat generated when In addition, the activation temperature of the connection member in the present invention is preferably in the range of 50 to 200 ° C. in consideration of the elongation amount of the IC chip and the elongation amount of the substrate.
[0010]
The present invention is characterized in that the difference between the extension amount of the substrate and the extension amount of the IC chip is minimized by heating each of the circuit board and the IC chip that face each other at the time of connection at a predetermined temperature. As shown in FIG. 6, the viscosity of the adhesive member is such that the connecting member is heated and pressurized by the crimping tool (a), the adhesive flows as the viscosity decreases, and conduction between the electrodes is ensured ( b: minimum viscosity of the present invention), and the viscosity rapidly increases as the curing reaction proceeds. For example, when the above-mentioned epoxy adhesive and latent curing agent are used for pressure bonding by the method shown in FIGS. 1 and 2 at a temperature of about 130 to 240 ° C., the state of the lowest viscosity is 2 to 10 seconds after the pressure bonding. Become. The heating temperature of the circuit board and the IC chip is as follows: thermal expansion coefficient (glass substrate; about 4.6 ppm / ° C., glass-epoxy substrate; about 14 ppm / ° C., IC chip; about 3 ppm / ° C.), elastic modulus (glass substrate; about (68.6 GPa, glass-epoxy substrate; 21 GPa, IC chip; about 169.8 GPa), thickness, etc., are preferably set so that the difference between the elongation amount of the substrate and the elongation amount of the IC chip is minimized.
Furthermore, it is preferable to preheat the circuit board before pressure bonding in order to increase the heating efficiency of the circuit board. At this time, when a circuit board with a connection member is used, it is necessary to perform preheating below the activation temperature of the adhesive. This is because when the preheating is performed at a temperature equal to or higher than the activation temperature, the reaction of the connection member proceeds and the connection reliability after connection is lowered.
[0011]
According to the present invention, the difference between the amount of elongation of the substrate and the amount of extension of the IC chip can be minimized by heating each of the circuit board and the IC chip facing each other at a predetermined temperature, so that warpage, cracks, etc. It is possible to provide a connection method that can reduce the deformation of. Further, by using this connection method, the stress concentration on the connection portion can be alleviated, so that the connection reliability can be improved.
[0012]
【Example】
Examples are described in detail below, but the present invention is not limited thereto.
Example 1
(1) Preparation of connecting member The ratio of phenoxy resin (high molecular weight epoxy resin) and liquid epoxy resin (epoxy equivalent 185) containing an amine microcapsule type latent curing agent as a film forming material is 20/80, and ethyl acetate A 30% solution of was obtained. To this solution, 5% by volume of conductive particles formed with a metal coating of Ni / Au thickness 0.2 / 0.02 μm were added to polystyrene particles having a particle diameter of 5 μm and mixed and dispersed. This dispersion was continuously applied to a PET substrate using a roll coater and dried at 80 ° C. for 10 minutes to obtain a connecting member having a thickness of 20 μm. The activation temperature of this connecting member is 135 ° C. Moreover, when it crimps | bonds by the method shown in FIG.1 and FIG.2 at the temperature of 130-200 degreeC, it will be in the state of the minimum viscosity about 3 seconds after crimping | compression-bonding.
(2) Evaluation IC chip (size 1.7 × 17 mm, chip thickness 0.55 mm, bump size 50 × 50 μm) having a gold-plated bump having a height of 15 μm on the connection IC bare chip, and a glass substrate (thickness 0.7 mm) And a planar electrode having a thin film circuit of indium oxide (thickness 0.2 μm, surface resistance 20Ω / □).
First, the connecting member was cut to a width of 2.0 mm and pasted on the electrode of the glass substrate. Next, after peeling off the PET base material separator, the IC chip and the substrate were aligned, followed by pressure bonding using the method shown in FIG. First, the glass substrate with the connecting member was preheated for 30 seconds on a pressure-bonding stage heated to 90 ° C. Next, using a pressure-bonding head heated to about 150 ° C., it was heated and pressed from above the IC chip for 20 seconds. At this time, it was IC bare chip; 150 degreeC, connection member; 140 degreeC, glass substrate;
[0013]
Example 2
Connection was performed using the same connection member, evaluation IC chip, and planar electrode as in Example 1.
First, the connecting member was cut to a width of 2.0 mm and pasted on the electrode of the glass substrate. Next, after peeling off the PET base material separator, the IC chip and the substrate were aligned, followed by pressure bonding using the method shown in FIG. Using an upper pressure-bonding head heated to about 150 ° C., the IC chip was heated and pressed for 20 seconds. At the same time, the lower pressure bonding head heated to about 130 ° C. was used to heat and press for 20 seconds from the glass substrate side. At this time, it was IC chip; 150 degreeC, a connection member; 140 degreeC, a glass substrate;
[0014]
Example 3
The same connection member and evaluation IC chip as in Example 1 were used. The board | substrate at this time used what has a copper circuit electrode (thickness 18 micrometers) on a glass epoxy board | substrate (thickness 0.7mm).
First, the connecting member was cut to a width of 2.0 mm and pasted on the electrode of the glass epoxy substrate. Next, after peeling the PET base material separator, the IC chip and the substrate were aligned. The pressure bonding was performed using the method shown in FIG. First, the substrate was placed on a pressure-bonding stage attached with a connecting member and cooled to about 5 ° C. for 30 seconds. Next, using a pressure-bonding head heated to about 150 ° C., it was heated and pressed from above the IC chip for 20 seconds. At this time, about 3 seconds after the pressure bonding, at which the connecting portion material had the lowest viscosity, the IC chip was 150 ° C., the connecting member was 135 ° C., the glass epoxy substrate was 40 ° C.
[0015]
Comparative Example 1
Connections were made using the same connection member, evaluation IC chip and planar electrode as in Example 1.
First, the connecting member was cut to a width of 2.0 mm and pasted on the electrode of the glass substrate. Next, after peeling off the PET base material separator, the IC bare chip and the substrate were aligned, followed by pressure bonding using the method shown in FIG. First, a glass substrate with a connection member was set on a crimping stage. At this time, the crimping stage is not heated and is about 25 ° C. Next, using a pressure-bonding head heated to about 150 ° C., it was heated and pressed from above the IC bare chip for 20 seconds. At this time, the IC bare chip: 150 ° C., the connecting member: 135 ° C., the glass substrate;
[0016]
Comparative Example 2
Connections were made using the same connection members as in Example 3, an evaluation IC chip, and a glass epoxy substrate.
First, the connecting member was cut to a width of 2.0 mm and pasted on the electrode of the glass epoxy substrate. Next, after peeling off the PET base separator, the IC chip and the substrate were aligned and then pressure-bonded using the method shown in FIG. First, a glass substrate with a connection member was set on a crimping stage. At this time, the crimping stage is not heated and is about 25 ° C. Next, using a pressure-bonding head heated to about 150 ° C., it was heated and pressed from above the IC bare chip for 20 seconds. At this time, the IC bare chip: 150 ° C., the connecting member: 137 ° C., the glass epoxy substrate: 65 ° C., after about 3 seconds after the pressure bonding at which the connecting portion material had the lowest viscosity.
[0017]
Evaluation 1
Using the connection bodies obtained in Examples 1 to 3 and Comparative Examples 1 and 2, the maximum warpage amount of the connection bodies was evaluated. The evaluation method measured the maximum curvature amount of the board | substrate in the IC chip mounting back surface using the surface shape measuring device (SE-3C by Kosaka Laboratory).
The obtained results are shown in Table 1. As is apparent from this result, it was found that the warpage between the IC chip and the substrate can be reduced by using the connection method of the present invention.
[0018]
[Table 1]

[0019]
Evaluation 2
The connection resistance value was evaluated using the connection bodies obtained in Examples 1 to 3 and Comparative Examples 1 and 2. In the evaluation method, a connection resistance value per bump size of 50 × 50 μm was measured using a resistance measuring machine. Further, this connection body was left in high temperature and high humidity (85 ° C., 85% RH) for 500 hours, and the change in connection resistance value was measured.
The obtained results are shown in Table 2. As is clear from this result, it was found that high connection reliability can be obtained by using the connection method of the present invention.
[0020]
[Table 2]

[0021]
【The invention's effect】
According to the present invention, the difference between the extension amount of the circuit board and the extension amount of the IC chip can be minimized by heating each of the circuit board and the IC chip facing each other at a predetermined temperature. The connection method which can reduce deformation | transformation etc. can be provided. Further, since the stress concentration on the connection portion can be alleviated, the connection reliability can be improved. Furthermore, by heating the circuit board below the activation temperature of the adhesive, it is possible to provide a connection method that is excellent in mass productivity and connection reliability after connection.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a connection method for explaining an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of a connection method for explaining another embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view of a connection member.
FIG. 4 is a schematic cross-sectional view of a connection member.
FIG. 5 is a schematic cross-sectional view of a multilayer connection member.
FIG. 6 is a diagram showing the behavior of the viscosity of a connection member.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Circuit board 2 IC chip 3 Connection member 4 Crimp stage 5 Crimp head 6 Insulating adhesive 7 Conductive material

Claims (3)

Between the connection electrodes of the circuit board and the IC chip, heat by shows an initial flow and a minimum viscosity, to place the connecting member is subsequently Rineba degree by the curing reaction a thermosetting insulating adhesive to rise, faced each other In a connection method consisting of electrical connection between electrodes and fixing between parts by heating and pressurizing between the electrodes,
The thermosetting insulating adhesive has a viscosity per unit time when the viscosity rises by a curing reaction after that, rather than the magnitude of the change in viscosity per unit time until the initial viscosity is exhibited by heat and the minimum viscosity is exhibited. The amount of change in the
By heating each of the circuit board and the IC chip facing each other at a predetermined temperature, the difference between the extension amount of the circuit board and the extension amount of the IC chip when the connecting member reaches the minimum viscosity after crimping is minimized. IC chip connection method characterized by the above. 2. The IC chip connection method according to claim 1, wherein the heating temperature of the circuit board is set to be equal to or lower than the activation temperature of the adhesive. 3. The IC chip connection method according to claim 1, wherein the circuit board is preheated at a temperature lower than an activation temperature of the adhesive before connection.

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