Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
  • H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
  • H05K3/321—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by conductive adhesives
  • H05K3/323—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by conductive adhesives by applying an anisotropic conductive adhesive layer over an array of pads
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J171/00—Adhesives based on polyethers obtained by reactions forming an ether link in the main chain; Adhesives based on derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2650/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
  • C08G2650/28—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule characterised by the polymer type
  • C08G2650/56—Polyhydroxyethers, e.g. phenoxy resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/05—Polymer mixtures characterised by other features containing polymer components which can react with one another
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
  • C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
  • C08L2666/04—Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/36—Assembling printed circuits with other printed circuits
  • H05K3/361—Assembling flexible printed circuits with other printed circuits
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]

Definitions

• the present invention relates to an anisotropic conductive film that bonds two circuit boards together and electrically connects mutually opposing circuits of different circuit boards without short-circuiting adjacent circuits in one circuit board. .
• Patent Document 1 discloses an example.
• an anisotropic conductive film a film in which conductive particles are dispersed in an adhesive film made of resin is used.
• the anisotropic conductive film By sandwiching the anisotropic conductive film between two circuit boards to be connected and thermocompression bonding, the two circuit boards are bonded by the anisotropic conductive film and the two circuit boards are opposed to each other. The circuits are electrically connected. At this time, it is required that adjacent circuits in the same circuit board are not short-circuited. Therefore, the anisotropic conductive film is required to have a connection performance with a low resistance (connection resistance) between circuits facing in the thickness direction and an insulation performance without short-circuiting between adjacent circuits in the surface direction. ing.
• An anisotropic conductive film is usually stored in the state of a film (in particular, the state of a film wound in a roll shape) until its mounting (when sandwiched between two circuit boards) after its manufacture. Therefore, excellent storage stability as a film is also desired.
• thermocompression bonding By using an anisotropic conductive film with excellent connection performance and insulation performance and performing the above-mentioned thermocompression bonding at a predetermined temperature and pressure, adhesion between the circuits and electrical connection are achieved, and between adjacent circuits. Insulation is also ensured.
• the temperature of thermocompression bonding that is, the mounting temperature of the anisotropic conductive film is too high, problems due to thermal damage of the circuit, thermal expansion / contraction difference, etc. occur. When placed in a high-humidity atmosphere, problems such as deterioration in connection performance over time tend to occur.
• thermocompression bonding temperature that is, the mounting temperature of the anisotropic conductive film is lower.
• time required for mounting that is, thermocompression bonding
• a highly conductive film Preferably, there is a need for an anisotropic conductive film that is further excellent in storage stability.
• the present invention can achieve sufficient electrical connection between circuit boards with a lower mounting temperature and shorter heating than conventional anisotropic conductive films, and the connection performance deteriorates over time in a high-temperature and high-humidity atmosphere. It is an object of the present invention to provide an anisotropic conductive film that does not have such problems.
• the above-mentioned problem is an anisotropic conductive film containing a radical polymerizable substance, a polymerization initiator that generates radicals upon heating, a phenoxy resin having a molecular weight of 30000 or more, and conductive particles, at a heating rate of 10 ° C./min.
• the anisotropic conductive film (first invention of the present application) characterized in that the DSC heat generation starting temperature when measured is 100 ° C. or lower and the DSC peak temperature is 120 ° C. or lower.
• the inventor used a film comprising a resin composition containing a radical polymerizable substance and its polymerization initiator together with a phenoxy resin as an adhesive film constituting an anisotropic conductive film, and the film
• the starting temperature of the thermosetting reaction can be made 100 ° C. or lower and the reaction peak temperature can be made 120 ° C. or lower, and the starting temperature and reaction of the hardening reaction
• the peak temperature within the above range, it is possible to achieve sufficient electrical connection between circuit boards at a low mounting temperature, and there is no problem such as deterioration of the connection performance over time in a high-temperature and high-humidity atmosphere.
• the present invention was completed by finding that a conductive film can be obtained.
• the starting temperature of the thermosetting reaction is defined as the DSC exothermic starting temperature when measured at a heating rate of 10 ° C./min.
• the reaction peak temperature is defined as the DSC peak temperature when measured at a heating rate of 10 ° C./min.
• the DSC peak temperature exceeds 120 ° C.
• the resistance between the opposing circuits of the two circuit boards cannot be lowered under a low mounting temperature condition, for example, heating at 140 ° C. for about 10 seconds. In this case, sufficient connection performance cannot be obtained.
• the thermosetting reaction starts at a low temperature and is quickly activated, thereby improving the reactivity at a low temperature. Excellent connection performance can be obtained even at low mounting temperatures.
• the difference between the DSC heat generation start temperature and the DSC peak temperature is small. Specifically, by setting the difference to 20 ° C. or less, further excellent connection performance can be obtained.
• the types of phenoxy resin, radical polymerizable substance, and polymerization initiator and their blending amounts are such that the DSC exotherm starting temperature is 100 ° C. or lower and the DSC peak temperature is 120 ° C. when measured at a temperature rising rate of 10 ° C./min. It is selected in the following range. As long as this condition is satisfied, the type and the blending amount thereof are not particularly limited, but the following are exemplified.
• the phenoxy resin constituting the anisotropic conductive film of the present invention is a high molecular weight polyhydroxy polyether synthesized from bisphenol and epihalohydrin.
• the bisphenol A is bisphenol A
• bisphenol A type phenoxy resins represented by the following structural formulas are given as representative examples. Fluorene ring-containing phenoxy resin, caprolactone-modified bisphenol A type phenoxy resin and the like can also be exemplified.
• the phenoxy resin is tough, flexible, has good adhesiveness, has excellent film forming properties, and is an essential component for forming an anisotropic conductive film.
• a phenoxy resin having a molecular weight of 30000 or more is used for forming an anisotropic conductive film.
• the molecular weight means a weight average molecular weight in terms of polystyrene measured by GPC.
• the radically polymerizable substance is selected from monomers and oligomers that undergo radical polymerization at a mounting temperature, for example, 140 ° C., and are compatible with a phenoxy resin having a molecular weight of 30000 or more.
• a mounting temperature for example, 140 ° C.
• examples thereof include acrylic acid esters and methacrylic acid esters.
• the radical polymerization initiator is compatible with a phenoxy resin having a molecular weight of 30,000 or more and is stable at room temperature, but generates radicals by heating at a mounting temperature, for example, 140 ° C., and the polymerization reaction of the radical polymerizable substance Selected from compounds having the ability to initiate Specific examples include peroxides, ketone peroxides, diacyl peroxides, peroxydicarbonates, peroxyesters, peroxyketals, dialkyl peroxides, hydroperoxides, and the like.
• Examples of the conductive particles dispersed in the organic binder component include metal particles such as gold, silver, copper, nickel, lead, tin, and alloys made of the above metals, such as solder, silver-copper alloy, etc.
• conductive particles such as carbon, conductive particles or non-conductive glass, ceramics, and plastic particles may be used as the core, and other conductive materials such as metal or ITO may be coated on the surface.
• the anisotropic conductive film is oriented by its own magnetism and can be oriented by using a magnetic field as will be described later. As a result, the anisotropic conductive film has excellent connection performance. Is preferable because it is easily obtained.
• the particle size of the conductive particles is preferably 0.05 to 20 ⁇ m. If the particle size is too small, the connection performance tends to be unstable, and if it is too large, a short circuit between adjacent circuits tends to occur, and the insulation performance tends to decrease.
• the blending amount of the conductive particles is preferably in the range of 0.01 to 20% by volume, more preferably based on the total volume of the radical polymerizable substance, the polymerization initiator that generates radicals upon heating, and the phenoxy resin having a molecular weight of 30000 or more. Is in the range of 0.03 to 5% by volume. When the blending amount of the conductive particles is too large, the insulation performance tends to be lowered, and when it is too little, the connection performance tends to be lowered.
• the second invention of the present application is the anisotropic conductive film according to the first invention of the present application, characterized in that the DSC heat generation starting temperature is 70 ° C. or higher when measured at a heating rate of 10 ° C./min.
• the DSC heat generation start temperature is too low, the storage stability of the anisotropic conductive film is lowered. This problem is particularly noticeable in the case of preservation in summer and tropical areas. If the DSC heat generation start temperature is 70 ° C. or higher, it is preferable because sufficient storage stability can be obtained even in the storage state where the temperature is high, such as in summer or in the tropical region.
• the third invention of the present application is the anisotropic conductive film of the first invention of the present application or the second invention of the present application, wherein the ratio of the length to the diameter of the conductive particles is 5 or more.
• conductive particles having a diameter to length ratio (aspect ratio) of 5 or more are used as the conductive particles used in the present invention, excellent connection performance is obtained even when the blending amount of the conductive particles is small. This is preferable because the insulating performance can be further improved.
• This aspect ratio can be directly measured by observation using a CCD microscope or the like.
• the aspect ratio is obtained using the maximum length of the cross section as the diameter.
• the conductive particles are bent or branched, the aspect ratio is obtained with the maximum length of the conductive particles as the length.
• the conductive particles having an aspect ratio of 5 or more include needle-shaped conductive particles, and examples thereof include those formed by connecting a large number of fine metal particles into a needle shape. More preferably, the aspect ratio is 10 to 100.
• the fourth invention of the present application is the anisotropic conductive film of the third invention of the present application, characterized in that the major axis direction of the conductive particles is oriented in the thickness direction of the film.
• conductive particles having an aspect ratio of 5 or more in the thickness direction of the film because the connection performance and insulation performance are further improved.
• the method for orienting the conductive particles in the thickness direction of the film is not particularly limited. However, when using conductive particles having ferromagnetism, the conductive particles are oriented in a resin solution in which conductive particles are dispersed as described below. A method of forming a film while applying a magnetic field in the direction to be generated can be mentioned.
• the anisotropic conductive film of the present invention is, for example, a plate in which conductive particles are dispersed in a resin solution in which a radical polymerizable substance, a polymerization initiator that generates radicals upon heating, and a phenoxy resin having a molecular weight of 30000 or more are dissolved in a solvent.
• the film can be formed by a method such as coating on the surface, and the solvent can be removed from the film.
• the solvent is not particularly limited as long as it can dissolve a radical polymerizable substance, a polymerization initiator, and a phenoxy resin and disperse the conductive particles. Among them, those which can be easily formed and have a low boiling point and can be easily removed by volatilization are preferable.
• the anisotropic conductive film of the present invention can be used for adhesion and electrical connection between two circuit boards by the same method as the conventional anisotropic conductive film. That is, by sandwiching the anisotropic conductive film of the present invention between two circuit boards to be connected and thermocompression bonding, the two circuit boards are bonded to each other and the two circuit boards are opposed to each other. The space is electrically connected. Since the anisotropic conductive film of this invention has the outstanding insulation performance, the short circuit between the adjacent circuits in the same circuit board does not arise in this case.
• the anisotropic conductive film of the present invention is capable of achieving sufficient electrical connection between circuit boards with a low mounting temperature and a short heating time, and the connection performance deteriorates over time in a high temperature and high humidity atmosphere. Nor.
• Conductive particles As the conductive particles, linear nickel fine particles having a long diameter distribution of 1 ⁇ m to 8 ⁇ m and a short diameter distribution of 0.1 ⁇ m to 0.4 ⁇ m were used.
• the conductive particles obtained above were blended in an amount of 0.1% by volume in the resin solution obtained above and dispersed. Then, it apply
• DSC measurement About the obtained anisotropic conductive film, DSC measurement was performed on the conditions shown below. The results are shown in Table 2.
• Equipment used Differential scanning calorimeter DSC-60, manufactured by Shimadzu Corporation Measurement conditions: Temperature rising rate 10 ° C./min
• a flexible printed circuit board in which 100 copper electrodes plated with gold of 100 ⁇ m width and 18 ⁇ m height are arranged at intervals of 100 ⁇ m, and 100 copper electrodes plated with gold of 100 ⁇ m width and 18 ⁇ m in height are arranged at intervals of 100 ⁇ m.
• a prepared glass epoxy substrate was prepared. The anisotropic conductive film obtained above is sandwiched between the flexible printed circuit board and the glass epoxy board, and is heated and bonded at 140 ° C. for 10 seconds under a pressure of 3 MPa. And a connected body of the glass epoxy substrate was obtained. The resistance value between the circuits of the flexible printed circuit board and the glass epoxy board was measured. This evaluation was repeated 10 times, and the average value of the connection resistance was obtained. These measured values were used as initial connection resistance values and are shown in Table 2.
• connection body was put into a constant temperature and humidity chamber set at a temperature of 85 ° C. and a humidity of 85%, taken out after the elapse of 500 hours, and the average value of connection resistance was obtained again in the same manner as described above.
• the measured values are shown in Table 2 as the connection resistance values after 500 hours of high temperature and high humidity.
• the DSC exotherm starting temperature is 100 ° C. or lower and the DSC peak temperature is 120 ° C. or lower (and the difference between the DSC exothermic starting temperature and the DSC peak temperature is 20 ° C. or lower).
• the anisotropic conductive film (Example of the present invention) of Example 2 was used, although the connection body was manufactured at a low mounting temperature (140 ° C., 3 MPa, heating for 10 seconds), the initial connection resistance Shows excellent connection performance.
• Table 2 shows that the connection resistance after being left in a high temperature and high humidity atmosphere for 500 hours is low and there is no problem that the connection performance deteriorates with time in the high temperature and high humidity atmosphere.
• the present invention can achieve sufficient electrical connection between circuit boards with a lower mounting temperature and shorter heating than conventional anisotropic conductive films, and the connection performance deteriorates over time in a high-temperature and high-humidity atmosphere.
• An anisotropic conductive film without such problems can be provided.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Non-Insulated Conductors (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Adhesive Tapes (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Combinations Of Printed Boards (AREA)
• Conductive Materials (AREA)

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• 2008
  • 2008-11-18 JP JP2008294655A patent/JP2010121007A/ja not_active Withdrawn
• 2009
  • 2009-08-27 CN CN2009801055333A patent/CN102273015A/zh active Pending
  • 2009-08-27 US US12/918,260 patent/US20100323147A1/en not_active Abandoned
  • 2009-08-27 KR KR1020107016558A patent/KR20110095127A/ko not_active Application Discontinuation
  • 2009-08-27 EP EP09827424A patent/EP2355253A1/en not_active Withdrawn
  • 2009-08-27 WO PCT/JP2009/064935 patent/WO2010058643A1/ja active Application Filing
  • 2009-11-17 TW TW098138922A patent/TW201027567A/zh unknown

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