JP2013016725A - Method for manufacturing connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a connection structure, by which an anisotropic conductive paste layer can be efficiently and accurately arranged.SOLUTION: In a method for manufacturing a connection structure 1 according to the present invention, a flexible printed board 4 which has a first projecting electrode 4b on a surface 4a and a projecting electronic component 4c having a projection height larger than that of the first electrode 4b on the surface 4a is used, and an anisotropic conductive paste layer 3A is arranged using an anisotropic conductive paste including a curable component and conductive particles 5, on a first coating region R1 on the first electrode 4b of the flexible printed board 4. Then, the flexible printed board 4 and a member 2 to be connected are laminated via the anisotropic conductive paste layer 3A, and the anisotropic conductive paste layer 3A is hardened. In the method for manufacturing the connection structure 1 according to the present invention, the anisotropic conductive paste is applied from a dispenser 12 while the dispenser 12 is being moved.

Description

  The present invention provides a method for manufacturing a connection structure in which an anisotropic conductive paste is applied on a flexible printed circuit board and the flexible printed circuit board and a connection target member are connected by a cured product layer obtained by curing the anisotropic conductive paste. About.

  Pasty or film-like anisotropic conductive materials are widely known. In the anisotropic conductive material, a plurality of conductive particles are dispersed in a binder resin.

  In order to obtain various connection structures, the anisotropic conductive paste is used, for example, for connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), connection between a semiconductor chip and a flexible printed circuit board (COF ( Chip on Film)), connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)), connection between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)), and the like.

  As an example of the method of applying the anisotropic conductive paste, the following Patent Document 1 discloses a lead frame in which each mount part for mounting a semiconductor chip or an electronic component or the like, or a part of the mount part is recessed from the upper surface. Alternatively, on a printed circuit board or the like, on the upper surface, a mask plate having a hole in each mount portion is provided, and a downward bulging portion is provided in a portion corresponding to the recessed mount portion of the mask plate. A screen printing method in which the conductive paste is supplied to the upper surface of the mask plate, and then the squeegee disposed on the upper surface side of the mask plate is moved while being pressed and in contact with the upper surface of the mask plate. It is disclosed.

JP 2003-80859 A

  As described in Patent Document 1, in the connection structure manufacturing method using the conventional screen printing method, when there is a convex portion on the surface of the connection target member on which the conductive paste is screen-printed, the screen is formed by the convex portion. The arrangement of the printing plate is hindered, or the interval between the screen printing plate and the connection target member needs to be increased.

  With respect to such a problem, in Patent Document 1, a screen printing plate is devised. Conventionally, it has been studied to devise a table on which a connection target member is placed. However, in these cases, it is necessary to produce a plurality of screen printing plates or to change the design of the table in accordance with the type of member to be connected. For this reason, the manufacturing cost of a connection structure becomes high. Furthermore, when the convex portion on the surface of the connection target member is large, it may be difficult to apply the conductive paste accurately and uniformly even if the screen printing plate or the table is devised.

  Furthermore, when the object to which the conductive paste is applied is a flexible printed circuit board, the flexible printed circuit board has a higher electrode height than the glass substrate. Therefore, in the screen printing method, the conductive paste is applied accurately and uniformly. There is a problem that it is even more difficult.

  The objective of this invention is providing the manufacturing method of the connection structure which can arrange | position an anisotropic conductive paste layer efficiently and accurately.

  According to a wide aspect of the present invention, using a flexible printed board having a protruding first electrode on the surface and a protruding electronic component having a protruding height larger than the first electrode on the surface, Disposing an anisotropic conductive paste layer in the first application region on the first electrode of the flexible printed circuit board using an anisotropic conductive paste containing a curable component and conductive particles; Using the connection target member having two electrodes on the surface, the first electrode and the second electrode are opposed to each other, and the flexible printed circuit board and the connection target member are connected to the anisotropic conductive paste layer. And laminating the anisotropic conductive paste layer, forming a cured product layer, in the step of disposing the anisotropic conductive paste layer, while moving the dispenser, Up The anisotropic conductive paste is applied from the dispenser, the manufacturing method of the connecting structure is provided.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, in the step of disposing the anisotropic conductive paste layer, the anisotropy is also applied to the second application region that is not on the first electrode. A conductive paste layer is disposed.

  In another specific aspect of the method for manufacturing a connection structure according to the present invention, the flexible printed circuit board includes a plurality of the first electrodes, the connection target member includes a plurality of the second electrodes, 2 application | coating area | regions contain the area | region of the clearance gap between several said 1st electrodes.

  In another specific aspect of the method for manufacturing a connection structure according to the present invention, the surface of the second application region of the flexible printed board does not protrude, or the protruding height is smaller than that of the first electrode. .

  In still another specific aspect of the method for manufacturing a connection structure according to the present invention, the surface of the second application region of the flexible printed board does not protrude.

  In another specific aspect of the method for manufacturing a connection structure according to the present invention, in the step of disposing the anisotropic conductive paste layer, the different disposition disposed in the first application region on the first electrode. The thickness of the anisotropic conductive paste layer portion is made thinner than the thickness of the anisotropic conductive paste layer portion disposed in the second application region that is not on the first electrode.

  In still another specific aspect of the method for manufacturing a connection structure according to the present invention, in the step of disposing the anisotropic conductive paste layer, the above-described disposed on the first coating region on the first electrode. The top surface of the anisotropic conductive paste layer portion and the top surface of the anisotropic conductive paste layer portion disposed in the second coating region not on the first electrode are smoothed so as to be continuous.

  In another specific aspect of the method for manufacturing a connection structure according to the present invention, in the step of disposing the anisotropic conductive paste layer, the different disposition disposed in the first application region on the first electrode. The thickness of the isotropic conductive paste layer portion is set to 3 times or more the average particle diameter of the conductive particles contained in the anisotropic conductive paste.

  In still another specific aspect of the method for manufacturing a connection structure according to the present invention, the flexible printed circuit board includes a plurality of the first electrodes, the connection target member includes a plurality of the second electrodes, The height of the first electrode is 5 μm or more, the gap between the plurality of first electrodes is 30 μm or less, and the anisotropic conductive paste has a viscosity of 200 Pa · s at 25 ° C. and 2.5 rpm. An anisotropic conductive paste having a viscosity ratio of 1 to 2 at a temperature of 25 Pa and 2.5 rpm and a viscosity at 25 C and 5 rpm is used.

  In the method for manufacturing a connection structure according to the present invention, a flexible printed circuit board having a protruding first electrode on the surface and a protruding electronic component having a protruding height larger than the first electrode on the surface. And using the anisotropic conductive paste containing a curable component and conductive particles in the first application region on the first electrode of the flexible printed circuit board to dispose an anisotropic conductive paste layer And the connection target member having the second electrode on the surface, the first electrode and the second electrode are opposed to each other, and the flexible printed circuit board and the connection target member are A step of laminating through the conductive paste layer and a step of curing the anisotropic conductive paste layer to form a cured product layer, and moving the dispenser in the step of arranging the anisotropic conductive paste layer The While, since applying the anisotropic conductive paste from the dispenser, the anisotropic conductive paste layer can be arranged efficiently and accurately.

FIG. 1 is a partially cutaway cross-sectional view schematically showing a connection structure obtained by a method for manufacturing a connection structure according to an embodiment of the present invention. 2A and 2B are a plan view and a cross-sectional view schematically showing a flexible printed board used in the method for manufacturing a connection structure according to an embodiment of the present invention. FIGS. 3A to 3C are partial cutaway cross-sectional views for explaining each step of the method for manufacturing the connection structure according to the embodiment of the present invention. 4A and 4B are diagrams for explaining a method of forming an anisotropic conductive paste layer into a B-stage using a coating apparatus in the method for manufacturing a connection structure according to an embodiment of the present invention. It is a schematic diagram. FIGS. 5A and 5B are schematic views for explaining another example of a method for forming an anisotropic conductive paste layer into a B-stage using a coating apparatus. 6A and 6B are a plan view and a cross-sectional view showing a modification of the flexible printed circuit board.

  Details of the present invention will be described below.

  The manufacturing method of the connection structure according to the present invention includes a flexible printed circuit board having a protruding first electrode on the surface and a protruding electronic component having a protruding height larger than that of the first electrode on the surface. And using the anisotropic conductive paste containing a curable component and conductive particles in the first application region on the first electrode of the flexible printed circuit board to dispose an anisotropic conductive paste layer And the connection target member having the second electrode on the surface, the first electrode and the second electrode are opposed to each other, and the flexible printed circuit board and the connection target member are A step of laminating through the conductive paste layer, and a step of curing the anisotropic conductive paste layer to form a cured product layer. In the method for manufacturing a connection structure according to the present invention, in the step of arranging the anisotropic conductive paste layer, the anisotropic conductive paste is applied from the dispenser while moving the dispenser.

  By adopting the above-described configuration in the method for manufacturing a connection structure according to the present invention, the anisotropic conductive paste layer can be arranged efficiently and accurately. For this reason, the hardened | cured material layer in the connection structure obtained can be arrange | positioned to a specific area | region accurately and uniformly. As a result, voids are less likely to occur in the resulting connection structure, and the connection reliability and conduction reliability between the flexible printed circuit board and the connection target member are increased. In particular, although the flexible printed circuit board has an electronic component protruding on the surface, it is possible to suppress the inhibition of the coating operation by the electronic component, so that the coating efficiency of the anisotropic conductive paste can be significantly increased.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  In FIG. 1, the connection structure obtained by the manufacturing method of the connection structure which concerns on one Embodiment of this invention is typically shown with sectional drawing. 2A and 2B are a plan view and a cross-sectional view showing a flexible printed circuit board used in the method for manufacturing a connection structure according to an embodiment of the present invention. FIG. 1 shows a cross-sectional view in a state where a connection target member is connected to the flexible printed circuit board along the line II in the flexible printed circuit board shown in FIG. FIG. 2B shows a cross-sectional view taken along line II-II shown in FIG.

  A connection structure 1 shown in FIG. 1 includes a connection target member 2, a flexible printed board 4, and a cured product layer 3. The cured product layer 3 connects the connection target member 2 and the flexible printed circuit board 4 and is a connection portion. The cured product layer 3 is formed by curing an anisotropic conductive paste containing a curable component and conductive particles 5. The anisotropic conductive paste includes a plurality of conductive particles 5.

  The connection target member 2 has a plurality of second electrodes 2b on the surface 2a. The plurality of second electrodes 2b protrude from the surface 2a. The flexible printed circuit board 4 has a plurality of first electrodes 4b on the surface 4a (first surface). The first electrode 4b protrudes from the surface 4a. The second electrode 2 b and the first electrode 4 b are electrically connected by one or a plurality of conductive particles 5.

  As shown in FIG. 2A, the flexible printed board 4 has an electronic component 4c on the surface 4a. The electronic component 4c is disposed on the same surface 4a as the side on which the first electrode 4b is disposed. The first electrode 4b and the electronic component 4c provided on the flexible printed board 4 protrude on the same surface 4a (first surface). As shown in FIG. 2A, the flexible printed board 4 is connected to the connection target member 2 in an area where the electronic component 4c is not provided. 6A and 6B, as shown in a plan view and a cross-sectional view, instead of the flexible printed board 4, the surface 61a has a first electrode 61b that protrudes linearly or linearly. Further, a flexible printed circuit board 61 having a protruding electronic component 61c having a protruding height larger than that of the first electrode 61b on the surface 61a may be used.

  On the surface 4a, the protruding height Hc of the electronic component 4c is larger than the protruding height Hb of the first electrode 4b. The protrusion height Hb of the first electrode 4b is preferably 10 μm or more, more preferably 15 μm or more, preferably 50 μm or less, more preferably 30 μm or less. The protruding height Hc of the electronic component 4c exceeds 1 times the protruding height Hb of the first electrode 4b, preferably 10 times or more, more preferably 20 times or more, preferably 200 times or less, more preferably 100 times. It is as follows. Even if the protrusion height Hc is larger than the protrusion height Hb, the anisotropic conductive paste layer can be efficiently and accurately applied by applying the anisotropic conductive paste from the dispenser while moving the dispenser. Can be placed.

  Examples of the electronic component 4c include a semiconductor chip and a connector. The electronic component 4c is preferably a semiconductor chip.

  The connection target member 2 is not particularly limited. Specific examples of the connection target member 2 include electronic components such as semiconductor chips, capacitors, and diodes, and electronic components that are circuit boards such as printed boards, flexible printed boards, glass boards, and glass epoxy boards. The connection target member 2 is preferably a glass substrate.

  The connection structure 1 can be obtained as follows. Here, the manufacturing method of the connection structure 1 when the anisotropic conductive paste containing a photocurable component, a thermosetting component, and the conductive particles 5 is used as the anisotropic conductive paste is specifically described. explain. That is, a method of manufacturing the connection structure 1 using an anisotropic conductive paste that can be cured by light irradiation and heat application will be described.

  First, the flexible printed circuit board 4 shown in FIGS. 2A and 2B is prepared. That is, the flexible printed circuit board 4 is prepared which has the protruding first electrode 4b on the surface 4a and the protruding electronic component 4c having a protruding height larger than that of the first electrode 4b on the surface 4a. The flexible printed circuit board 4 is arranged such that the surface 4a on the side where the first electrode 4b and the electronic component 4c are provided is on the upper side. Next, as shown in FIG. 3A, an anisotropic conductive paste containing a photocurable component, a thermosetting component, and conductive particles 5 is applied to the surface 4 a of the flexible printed circuit board 4 to be flexible. An anisotropic conductive paste layer 3 </ b> A is formed on the surface 4 a of the printed board 4. The anisotropic conductive paste layer 3A is an anisotropic conductive paste layer immediately after coating. At this time, it is preferable that one or a plurality of conductive particles 5 be disposed on the first electrode 4b. Here, the anisotropic conductive paste is linearly applied to the surface 4a of the flexible printed circuit board 4 in the direction indicated by the arrow X in FIG. Further, the anisotropic conductive paste is applied in the region surrounded by the broken line Y in FIG. Note that when the flexible printed circuit board 4 and the connection target member 2 are connected, the anisotropic conductive paste layer or the B-staged anisotropic conductive paste layer also extends outside the region surrounded by the broken line Y.

  4A and 4B are schematic views showing a state when applying the anisotropic conductive paste. In FIG. 4A and FIG. 4B, the first electrode 4b and the electronic component 4c are not shown. In order to form the anisotropic conductive paste layer 3A, a coating apparatus 11 shown in FIG. 4A is preferably used. In FIG. 4A, the movement direction of the dispenser 12 and the application direction of the anisotropic conductive paste are directions from the right side to the left side.

  The coating device 11 is used to apply an anisotropic conductive paste containing a curable component and conductive particles 5 to the surface 4 a of the flexible printed circuit board 4. The coating device 11 includes a dispenser 12 and a light irradiation device 13 connected to the dispenser 12. The dispenser 12 includes a syringe 12a for filling the inside with an anisotropic conductive paste, and a grip portion 12b that grips the outer peripheral surface of the syringe 12a. The light irradiation device 13 includes a light irradiation device main body 13a and a light irradiation unit 13b.

  The dispenser 12 is a dispenser for applying the anisotropic conductive paste to the surface 4 a of the flexible printed board 4. The light irradiation device 13 is a light irradiation device for applying the anisotropic conductive paste to the surface 4a of the flexible printed circuit board 4 and irradiating the anisotropic conductive paste with light.

  As shown in FIG. 4A, when applying the anisotropic conductive paste, the syringe 12a of the dispenser 12 is placed on the surface 4a of the flexible printed circuit board 4 while moving the coating device 11 in the direction of arrow A. An anisotropic conductive paste is applied from the tip 12c to form the anisotropic conductive paste layer 3A.

  As shown in FIG. 2A, the anisotropic conductive paste layer 3A is disposed in the first application region R1 on the first electrode 4b of the flexible printed circuit board 4. Furthermore, it is preferable to dispose the anisotropic conductive paste layer 3A also in the second application region R2 that is not on the first electrode 4b. Here, the area | region of the clearance gap between several 1st electrode 4b is 2nd application | coating area | region R2. Thus, the flexible printed circuit board 4 has a plurality of first electrodes 4b, the connection target member 2 has a plurality of second electrodes 2b, and the second application region R2 is between the plurality of first electrodes 4b. It is preferable to include a gap region. It is preferable that the anisotropic conductive paste layer 3A is disposed by continuously applying the anisotropic conductive paste to the first application region R1 and the second application region R2. It is preferable to apply the anisotropic conductive paste by continuously passing the dispenser 12 through the first application region R1 and the second application region R2.

  It is preferable that the surface 4a of the second application region R2 of the flexible printed circuit board 4 does not protrude or has a protrusion height smaller than that of the first electrode 4b, and the surface of the second application region R2 of the flexible printed circuit board 4 4a is preferably not protruding. In this case, the surface 4a of the flexible printed circuit board 4 is uneven by a first application region R1 on the first electrode 4b and a second application region R2 that is not on the first electrode 4b. It is preferable to dispose the anisotropic conductive paste layer 3A in a region where the surface 4a of the flexible printed board 4 does not protrude or a region where the degree of protrusion is smaller than that of the first electrode 4b.

  The thickness of the portion of the anisotropic conductive paste layer 3A disposed in the first application region R1 on the first electrode 4b is set to the anisotropy disposed in the second application region R2 not on the first electrode 4b. It is preferable to make it thinner than the thickness of the conductive paste layer 3A portion. In this case, the unevenness of the upper surface 3a of the anisotropic conductive paste layer 3A disposed over the first and second application regions R1 and R2 can be reduced. As a result, voids are less likely to occur in the connection structure, and connection reliability can be improved.

  As shown in FIG. 3A, the upper surface of the anisotropic conductive paste layer 3A portion disposed in the first application region R1 on the first electrode 4b and the second application not on the first electrode 4b. It is preferable to smooth the upper surface of the anisotropic conductive paste layer 3A portion arranged in the region R2 so as to be continuous. In this case, in the connection structure, voids can be made more difficult to occur, and connection reliability can be further improved.

  It is preferable that the height of the first electrode 4b is 5 μm or more, and the gap between the plurality of first electrodes 4b is 30 μm or less. When an anisotropic conductive paste layer is arranged on the surface of a flexible printed board having such a first electrode, it is quite difficult to arrange the anisotropic conductive paste layer accurately and uniformly by screen printing. It is. On the other hand, the anisotropic conductive paste layer can be accurately and uniformly disposed by applying the anisotropic conductive paste from the dispenser while moving the dispenser. Further, the second electrode 2 b of the connection target member 2 is preferably disposed at a position corresponding to the first electrode 4 b of the flexible printed circuit board 4. It is preferable that the space | interval of the clearance gap (space) between several 2nd electrode 2b is 30 micrometers or less.

  The anisotropic conductive paste has a viscosity η1 at 25 ° C. and 2.5 rpm of more than 200 Pa · s and preferably 800 Pa · s or less. The viscosity η1 is more preferably 300 Pa · s or more, and more preferably 500 Pa · s or less. When the viscosity η1 is not less than the above lower limit and not more than the above upper limit, in the connection structure using the specific flexible printed circuit board, voids are further hardly generated and connection reliability can be further improved.

  The viscosity ratio (η2 / η3) of the anisotropic conductive paste to the viscosity η3 at 25 ° C. and 5 rpm of the viscosity η2 at 25 ° C. and 2.5 rpm is preferably 1 or more and 2 or less. The viscosity ratio (η2 / η3) is more preferably 1.1 or more, and more preferably 1.5 or less. When the viscosity ratio (η2 / η3) is not less than the above lower limit and not more than the above upper limit, in the connection structure using the flexible printed circuit board, voids are further less likely to be generated, and connection reliability is further improved. it can.

  The flexible printed circuit board has a plurality of the first electrodes, the connection target member has a plurality of the second electrodes, and the height of the first electrodes is 5 μm or more, and between the plurality of the first electrodes. It is particularly preferable that the gap interval is 30 μm or less, the viscosity η1 exceeds 200 Pa · s and is 800 Pa · s or less, and the viscosity ratio (η2 / η3) is 1 or more and 2 or less. In particular, when the interval between the plurality of first electrodes is narrow, it is very difficult to accurately and uniformly dispose the anisotropic conductive paste layer in the narrow gap region between the plurality of first electrodes. . On the other hand, while moving the dispenser, by applying an anisotropic conductive paste having the viscosity η1 and the viscosity ratio (η2 / η3) that are equal to or higher than the lower limit and equal to or lower than the upper limit, the narrowness is achieved. The anisotropic conductive paste layer can be accurately and evenly disposed in the gap region. For this reason, in a connection structure, it becomes difficult to produce a void still more effectively and can improve connection reliability still more effectively.

  The thickness of the portion of the anisotropic conductive paste layer 3A disposed in the first application region R1 on the first electrode 4b is 3 as the average particle diameter of the conductive particles 5 contained in the anisotropic conductive paste. It is preferable to make it twice or more. In this case, in the connection structure, voids can be made more difficult to occur, and connection reliability can be further improved. The thickness of the portion of the anisotropic conductive paste layer 3A disposed in the first application region R1 on the first electrode 4b is 4 as the average particle diameter of the conductive particles 5 included in the anisotropic conductive paste. It is more preferable to make it double or more, and it is preferable to make it 10 times or less. In this case, generation of voids in the connection structure can be further suppressed.

  Next, the anisotropic conductive paste layer 3A is cured by irradiating the anisotropic conductive paste layer 3A with light. Curing of the anisotropic conductive paste layer 3A is advanced to make the anisotropic conductive paste layer 3A B-staged. By forming the anisotropic conductive paste layer 3A into a B-stage, the B-staged anisotropic conductive paste layer 3B is formed on the surface 4a of the flexible printed circuit board 4 as shown in FIG. 3B.

  As shown in FIG. 4B, when irradiating light, light is applied to the anisotropic conductive paste layer 3A from the light irradiation unit 13b of the light irradiation device 13 connected to the dispenser 12 as indicated by an arrow B. Irradiate. Here, the anisotropic conductive paste layer 3A is irradiated with light from the light irradiation unit 13b of the light irradiation device 13 connected to the dispenser 12 as indicated by an arrow B while applying the anisotropic conductive paste. Yes.

  It is preferable to irradiate the anisotropic conductive paste layer 3 </ b> A with light while applying the anisotropic conductive paste to the surface 4 a of the flexible printed circuit board 4. Furthermore, it is also preferable to irradiate the anisotropic conductive paste layer 3 </ b> A with light immediately after the application of the anisotropic conductive paste to the surface 4 a of the flexible printed board 4 or immediately after the application. When the application and the light irradiation are performed as described above, the flow of the anisotropic conductive paste layer 3A or the B-staged anisotropic conductive paste layer 3B can be further suppressed. For this reason, the connection reliability between the flexible printed circuit board 4 and the connection target member 2 and the conduction reliability between the first and second electrodes 4b and 2b are further enhanced. From the viewpoint of controlling the time until light irradiation with high accuracy, it is preferable to move the dispenser 12 and the light irradiation device 13, and it is preferable to move the dispenser 12 and the light irradiation device 13 in conjunction with each other. 12 and the light irradiation device 13 are preferably moved at the same speed. Thus, it is preferable to apply the anisotropic conductive paste and move the anisotropic conductive paste layer 3 </ b> A to light while moving the dispenser 12 and the light irradiation device 13. The time from the application of the anisotropic conductive paste to the surface 4a of the flexible printed board 4 to the irradiation with light is 0 second or more, preferably 3 seconds or less, more preferably 2 seconds or less. However, the table 31 may be moved in the direction opposite to the arrow A without moving the coating apparatus 11.

  In the coating device 11, the dispenser 12 and the light irradiation device 13 are connected by connecting the grip portion 12b and the light irradiation device main body 13a. Accordingly, the dispenser 12 and the light irradiation device 13 can be moved in conjunction with each other, and the dispenser 12 and the light irradiation device 13 can be moved at the same speed. Furthermore, the distance between the dispenser 12 and the light irradiation device 13 can be reduced, that is, the distance between the discharge part of the dispenser 12 and the light irradiation part 13b can be reduced. As a result, the anisotropic conductive paste layer 3A applied by the dispenser 12 can be quickly irradiated with light. In addition, the syringe 12a and the light irradiation apparatus main body 13a may be directly connected.

  In order to irradiate the anisotropic conductive paste layer 3A with light, as shown in FIGS. 5A and 5B, a dispenser 12 and a light irradiation device 21 not connected to the dispenser 12 may be used. Good. Similar to the light irradiation device 13, the light irradiation device 21 includes a light irradiation device main body 21 a and a light irradiation unit 21 b. The light irradiation device 21 is configured to irradiate light over a wider area than the light irradiation device 13. In FIGS. 5A and 5B, illustration of the first electrode 4b and the electronic component 4c is omitted.

  When using the dispenser 12 and the light irradiation device 21 not connected to the dispenser 12, for example, the light irradiation device 21 is disposed above the flexible printed circuit board 4 as shown in FIG. Next, while moving the dispenser 12 in the direction of arrow A between the flexible printed circuit board 4 and the light irradiation device 21, the anisotropic conductive paste is applied from the syringe 12a to the surface 4a of the flexible printed circuit board 4, An anisotropic conductive paste layer 3A is formed. Next, as shown in FIG. 5 (b), after the application of the anisotropic conductive paste is completed, from the light irradiation unit 21 b of the light irradiation device 21 disposed above the flexible printed board 4, the arrow B As shown, the anisotropic conductive paste layer 3A is irradiated with light. The light irradiation is performed, for example, simultaneously with the application of the anisotropic conductive paste or immediately after the application.

  It is preferable that the light irradiation device 21 is disposed above the flexible printed circuit board 4 during application. In this case, light can be irradiated quickly after application. After application, it is preferable to irradiate the entire region of the anisotropic conductive paste layer 3A with light. In this case, the anisotropic conductive paste layer 3A can be made B-stage more uniformly.

The light irradiation intensity for causing the anisotropic conductive paste layer 3 </ ^b > A to be B-staged by light irradiation and causing the curing to proceed appropriately is, for example, preferably about 0.1 to 10,000 mW / cm ² . Moreover, the light irradiation energy for advancing moderately curing the anisotropic conductive paste layer 3A is preferably 50 mJ / cm ² or more, more preferably 100 mJ / cm ² or more, preferably 100000mJ / cm ² or less, more Preferably it is 50000 mJ / cm ² or less.

  The light source used when irradiating light is not specifically limited. Examples of the light source include a light source having a sufficient light emission distribution at a wavelength of 420 nm or less. Specific examples of the light source include, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, a metal halide lamp, and an LED lamp.

  Alternatively, the anisotropic conductive paste layer 3A may be B-staged by applying heat, without making the anisotropic conductive paste layer 3A B-staged by light irradiation. When hardening is performed by applying heat to the anisotropic conductive paste layer 3A to make the anisotropic conductive paste layer 3A B-stage, the anisotropic conductive paste layer 3A is appropriately B-staged. The heating temperature for this is preferably 80 ° C or higher, preferably 150 ° C or lower, more preferably 120 ° C or lower. Even when the anisotropic conductive paste layer 3A is B-staged by applying heat instead of irradiating light, as long as the anisotropic conductive paste is applied from the dispenser 12 as described above, the first and second The positional deviation between the electrodes 4b and 2b can be suppressed.

  Next, as shown in FIG. 3C, the connection target member 2 is laminated on the upper surface 3a of the B-staged anisotropic conductive paste layer 3B. The connection target member 2 is laminated so that the first electrode 4b on the surface 4a of the flexible printed circuit board 4 and the second electrode 2b on the surface 2a of the connection target member 2 face each other. In addition, after lamination | stacking of the connection object member 2, in order to make the anisotropic conductive paste layer 3B into B stage, you may irradiate light and may provide heat. However, after the connection target member 2 is laminated, it is preferable to apply heat or irradiate light in order to make the anisotropic conductive paste layer 3A into a B-stage.

  Further, when the connection target member 2 is laminated, the B-staged anisotropic conductive paste layer 3 </ b> B is heated and hardened to form the cured product layer 3. However, the anisotropic conductive paste layer 3B may be heated before the connection target member 2 is laminated. However, it is preferable that the anisotropic conductive paste layer 3B is heated and fully cured after the connection target members 2 are stacked.

  In order to cure the anisotropic conductive paste layer 3B by application of heat, the heating temperature for sufficiently curing the anisotropic conductive paste layer 3B is preferably 160 ° C. or higher, preferably 250 ° C. or lower, more preferably 200 It is below ℃.

  When the anisotropic conductive paste layer 3A is not B-staged without applying heat or irradiating light to the anisotropic conductive paste layer 3A, the upper surface 3a of the anisotropic conductive paste layer 3A is connected. The member 2 may be laminated and the anisotropic conductive paste layer 3A may be heated to be fully cured.

  It is preferable to apply pressure when the anisotropic conductive paste layer 3B is cured. By compressing the conductive particles 5 with the first electrode 4b and the second electrode 2b by pressurization, the contact area between the first and second electrodes 4b, 2b and the conductive particles 5 can be increased. it can. For this reason, conduction reliability can be improved.

  By curing the anisotropic conductive paste layer 3 </ b> B, the flexible printed circuit board 4 and the connection target member 2 are connected via the cured product layer 3. In addition, the first electrode 4 b and the second electrode 2 b are electrically connected through the conductive particles 5. In this way, the connection structure 1 shown in FIG. 1 can be obtained. In this embodiment, since photocuring and thermosetting are used together, the anisotropic conductive paste can be cured in a short time.

  In addition, when the connection structure is produced, the anisotropic conductive paste is made into a B-stage by applying heat or irradiating light, and then cured to form an anisotropic paste layer disposed on the flexible printed circuit board. The contained conductive particles are difficult to flow greatly in the curing stage. Accordingly, the conductive particles are easily arranged in a predetermined region. Specifically, conductive particles can be arranged between upper and lower electrodes to be connected, and adjacent electrodes that should not be connected are electrically connected via a plurality of conductive particles. Can be suppressed. For this reason, the conduction | electrical_connection reliability between the electrodes in a connection structure can be improved.

  In addition, when the anisotropic conductive paste is made into a B stage by applying heat or irradiating with light at the time of producing the connection structure, the influence of the surface shape of the anisotropic conductive paste layer before the B stage is made. Therefore, the first and second electrodes tend to be misaligned. For example, in the B-staged anisotropic conductive paste layer, the viscosity has increased to some extent due to the B-stage. For example, there is a large protrusion or recess on the upper surface of the B-staged anisotropic conductive paste layer. If it exists, in the connection structure obtained, there exists a tendency for the position shift between the electrodes in the 1st, 2nd connection object member to arise easily.

  On the other hand, by reducing the unevenness of the upper surface 3a of the anisotropic conductive paste layer 3A disposed in the entire first and second coating regions R1 and R2, or by eliminating the unevenness and smoothing it, B Even if the stage is made, it is possible to effectively suppress the positional deviation between the electrodes in the first and second connection target members.

  On the other hand, the viscosity of the anisotropic conductive paste layer before the B-stage is too low when the anisotropic conductive paste is not B-staged by applying heat or irradiating the light at the time of producing the connection structure. Thus, in the obtained connection structure, there is a tendency that misalignment between the first and second electrodes is likely to occur.

  On the other hand, when the connection structure is produced, the anisotropic conductive paste is made into a B-stage by applying heat or irradiating light, so that the positional deviation between the electrodes in the first and second connection target members is reduced. It can be effectively suppressed.

  The connection structure manufacturing method according to the present invention includes, for example, a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), a connection between a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), Or it can use for the connection (FOB (Film on Board)) etc. of a flexible printed circuit board and a glass epoxy board | substrate. The manufacturing method of the connection structure according to the present invention is suitable for FOG use. In the method for manufacturing a connection structure according to the present invention, it is preferable to use a glass substrate as the connection target member.

  The anisotropic conductive paste includes a curable component and conductive particles. The curable component preferably includes a thermosetting component. The curable component may contain a photocurable component. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent. The anisotropic conductive paste preferably further includes a photocurable component in addition to the thermosetting component. The photocurable component preferably contains a photocurable compound and a photocuring initiator. The anisotropic conductive paste preferably contains a thermosetting compound as a curable compound and further contains a photocurable compound. The thermosetting compound is preferably a compound having an epoxy group or a thiirane group. The photocurable compound is preferably a compound having a (meth) acryloyl group.

  Hereinafter, each component contained in the anisotropic conductive paste and details of each component preferably contained will be described.

[Thermosetting compound]
The thermosetting compound has thermosetting properties. As for the said thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  Examples of the thermosetting compound include oxetane compounds, epoxy compounds, episulfide compounds, (meth) acrylic compounds, phenolic compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds. As for the said thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of easily controlling the curing of the anisotropic conductive paste or further improving the conduction reliability in the connection structure, the thermosetting compound is a thermosetting compound having an epoxy group or a thiirane group. It is preferable that a thermosetting compound having a thiirane group is included. The thermosetting compound having an epoxy group is an epoxy compound. The thermosetting compound having a thiirane group is an episulfide compound. From the viewpoint of enhancing the curability of the anisotropic conductive paste, the content of the compound having an epoxy group or thiirane group is preferably 10% by weight or more, more preferably 20% by weight in 100% by weight of the thermosetting compound. % Or more and 100% by weight or less. The total amount of the thermosetting compound may be a compound having the epoxy group or thiirane group.

  Since the episulfide compound has a thiirane group instead of an epoxy group, it can be quickly cured at a low temperature. That is, the episulfide compound having a thiirane group can be cured at a lower temperature derived from the thiirane group as compared with the epoxy compound having an epoxy group.

  The thermosetting compound having an epoxy group or thiirane group preferably has an aromatic ring. Examples of the aromatic ring include a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, tetracene ring, chrysene ring, triphenylene ring, tetraphen ring, pyrene ring, pentacene ring, picene ring, and perylene ring. Especially, it is preferable that the said aromatic ring is a benzene ring, a naphthalene ring, or an anthracene ring, and it is more preferable that it is a benzene ring or a naphthalene ring. A naphthalene ring is preferred because it has a planar structure and can be cured more rapidly.

[Photocurable compound]
The anisotropic conductive paste preferably contains a photocurable compound so as to be cured by irradiation with light. The photocurable compound can be semi-cured (B-staged) by irradiation with light to reduce the fluidity of the anisotropic conductive paste.

  The photocurable compound is not particularly limited, and examples thereof include a photocurable compound having a (meth) acryloyl group and a photocurable compound having a cyclic ether group.

  The photocurable compound is preferably a photocurable compound having a (meth) acryloyl group. By using the photocurable compound having a (meth) acryloyl group, the conduction reliability of the connection structure can be further enhanced. From the viewpoint of effectively increasing the conduction reliability of the resulting connection structure, the photocurable compound preferably has one or two (meth) acryloyl groups.

  The photocurable compound having the (meth) acryloyl group has no epoxy group and thiirane group, and has a (meth) acryloyl group, and has an epoxy group or thiirane group, and ( The photocurable compound which has a (meth) acryloyl group is mentioned.

  As a photocurable compound having the above (meth) acryloyl group, an ester compound obtained by reacting a compound having (meth) acrylic acid and a hydroxyl group, an epoxy obtained by reacting (meth) acrylic acid and an epoxy compound. (Meth) acrylate or urethane (meth) acrylate obtained by reacting a (meth) acrylic acid derivative having a hydroxyl group with isocyanate is preferably used. The “(meth) acryloyl group” refers to an acryloyl group and a methacryloyl group. The “(meth) acryl” refers to acryl and methacryl. The “(meth) acrylate” refers to acrylate and methacrylate.

  The ester compound obtained by making the said (meth) acrylic acid and the compound which has a hydroxyl group react is not specifically limited. As the ester compound, any of a monofunctional ester compound, a bifunctional ester compound, and a trifunctional or higher functional ester compound can be used.

  The photocurable compound having the epoxy group or thiirane group and having a (meth) acryloyl group is a part of the epoxy group or part of thiirane of the compound having two or more epoxy groups or two or more thiirane groups. It is preferable that it is a photocurable compound obtained by converting a group into a (meth) acryloyl group. Such a photocurable compound is a partially (meth) acrylated epoxy compound or a partially (meth) acrylated episulfide compound.

  The photocurable compound is preferably a reaction product of a compound having two or more epoxy groups or two or more thiirane groups and (meth) acrylic acid. This reaction product is obtained by reacting a compound having two or more epoxy groups or two or more thiirane groups with (meth) acrylic acid in the presence of a basic catalyst according to a conventional method. It is preferable that 20% or more of the epoxy group or thiirane group is converted (converted) to a (meth) acryloyl group. The conversion is more preferably 30% or more, preferably 80% or less, more preferably 70% or less. Most preferably, 40% or more and 60% or less of the epoxy group or thiirane group is converted to a (meth) acryloyl group.

  Examples of the partially (meth) acrylated epoxy compound include bisphenol type epoxy (meth) acrylate, cresol novolac type epoxy (meth) acrylate, carboxylic acid anhydride-modified epoxy (meth) acrylate, and phenol novolac type epoxy (meth) acrylate. Is mentioned.

  As the photocurable compound, a modified phenoxy resin obtained by converting a part of epoxy groups or a part of thiirane groups of a phenoxy resin having two or more epoxy groups or two or more thiirane groups into (meth) acryloyl groups is used. Also good. That is, a modified phenoxy resin having an epoxy group or thiirane group and a (meth) acryloyl group may be used.

  Further, the photocurable compound may be a crosslinkable compound or a non-crosslinkable compound.

  Specific examples of the crosslinkable compound include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, (poly ) Ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, glycerol methacrylate acrylate, pentaerythritol tri (meth) acrylate, tri Examples include methylolpropane trimethacrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, polyester (meth) acrylate, and urethane (meth) acrylate.

  Specific examples of the non-crosslinkable compound include ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) ) Acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, decyl (Meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, and the like.

  When using a photocurable compound, the compounding ratio of a photocurable compound and a thermosetting compound is suitably adjusted according to the kind of a photocurable compound and a thermosetting compound. The anisotropic conductive paste preferably contains a photocurable compound and a thermosetting compound in a weight ratio of 1:99 to 90:10, more preferably 5:95 to 70:30, More preferably, it is included at 10:90 to 50:50. The anisotropic conductive paste particularly preferably contains a photocurable compound and a thermosetting compound in a weight ratio of 1:99 to 50:50.

(Thermosetting agent)
The anisotropic conductive paste preferably contains a thermosetting agent. The curing agent includes a thermal radical initiator. As for a thermosetting agent, only 1 type may be used and 2 or more types may be used together.

  The said thermosetting agent is not specifically limited. Examples of the thermosetting agent include an imidazole thermosetting agent, an amine thermosetting agent, a phenol thermosetting agent, a polythiol thermosetting agent, an acid anhydride, and a thermal radical initiator. Especially, since an anisotropic electrically conductive paste can be hardened more rapidly at low temperature, an imidazole thermosetting agent, a polythiol thermosetting agent, or an amine thermosetting agent is preferable. Moreover, since the storage stability of anisotropic conductive paste can be improved, a latent thermosetting agent is preferable. The latent thermosetting agent is preferably a latent imidazole thermosetting agent, a latent polythiol thermosetting agent, or a latent amine thermosetting agent. In addition, the said thermosetting agent may be coat | covered with polymeric substances, such as a polyurethane resin or a polyester resin.

  The imidazole thermosetting agent is not particularly limited, but 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2 , 4-Diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine and 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s -A triazine isocyanuric acid adduct etc. are mentioned.

  Examples of the polythiol thermosetting agent include, but are not limited to, trimethylolpropane tris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate. It is done.

  Although it does not specifically limit as said amine thermosetting agent, Hexamethylene diamine, octamethylene diamine, decamethylene diamine, 3,9-bis (3-aminopropyl) 2,4,8,10-tetraspiro [5.5] Examples include undecane, bis (4-aminocyclohexyl) methane, metaphenylenediamine, and diaminodiphenylsulfone.

  The thermal radical initiator is not particularly limited, and examples thereof include azo compounds and peroxides. Examples of the peroxide include diacyl peroxide compounds, peroxyester compounds, hydroperoxide compounds, peroxydicarbonate compounds, peroxyketal compounds, dialkyl peroxide compounds, and ketone peroxide compounds.

  Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), and 2,2′-azobis (2,4-dimethylvaleronitrile). 1,1′-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2′-azobisisobutyrate, dimethyl-2,2′-azobis (2-methylpropionate), dimethyl-1,1 ′ -Azobis (1-cyclohexanecarboxylate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-amidinopropane) dihydrochloride, 2-tert-butylazo-2-cyanopropane 2,2′-azobis (2-methylpropionamide) dihydrate, 2,2′-azobis (2,4,4-trimethylpentane), and the like.

  Examples of the diacyl peroxide compound include benzoyl peroxide, diisobutyryl peroxide, di (3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, and disuccinic acid peroxide. Examples of the peroxyester compound include cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, tert-hexylperoxyneodecanoate, and tert-butylperoxyneo. Decanoate, tert-butylperoxyneoheptanoate, tert-hexylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2 , 5-di (2-ethylhexanoylperoxy) hexane, tert-hexylperoxy-2-ethylhexanoate, tert-butylperoxypivalate, tert-butylperoxy-2-ethylhexanoate, tert -Butyl peroxyisobutyrate, tert-butyl per Kishiraureto, tert- butylperoxy isophthalate, tert- butylperoxy acetate, tert- butylperoxy octoate and tert- butyl peroxybenzoate, and the like. Examples of the hydroperoxide compound include cumene hydroperoxide and p-menthane hydroperoxide. Examples of the peroxydicarbonate compound include di-sec-butyl peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-n-propyl peroxydicarbonate, diisopropyl peroxycarbonate, and di- (2-ethylhexyl) peroxycarbonate and the like. Other examples of the peroxide include methyl ethyl ketone peroxide, potassium persulfate, and 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane.

  The decomposition temperature for obtaining the 10-hour half-life of the thermal radical initiator is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, preferably 80 ° C. or lower, more preferably 70 ° C. or lower. When the decomposition temperature for obtaining the 10-hour half-life of the thermal radical initiator is less than 30 ° C., the storage stability of the anisotropic conductive paste tends to be lowered. It tends to be difficult to sufficiently heat cure the conductive paste.

  The content of the thermosetting agent is not particularly limited. Content of the said hardening | curing agent is suitably adjusted according to the kind of hardening | curing agent. The content of the thermosetting agent is preferably 0.01 parts by weight or more and preferably 200 parts by weight or less with respect to 100 parts by weight of the thermosetting compound.

  When the thermosetting agent is a thermosetting agent other than a thermal radical initiator, the content of the thermosetting agent is preferably 0.01 parts by weight or more, more preferably, with respect to 100 parts by weight of the thermosetting compound. Is 30 parts by weight or more, preferably 200 parts by weight or less, more preferably 100 parts by weight or less, still more preferably 75 parts by weight or less, and particularly preferably 40 parts by weight or less. When the content of the thermosetting agent is not less than the above lower limit, it is easy to sufficiently cure the anisotropic conductive paste. When the content of the thermosetting agent is not more than the above upper limit, it is difficult for an excess thermosetting agent that did not participate in curing after curing to remain, and the heat resistance of the cured product is further enhanced.

  When the thermosetting agent is a thermal radical initiator, the content of the thermal radical initiator is not particularly limited. The content of the thermal radical initiator is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, preferably 10 parts by weight or less, more preferably 100 parts by weight of the thermosetting compound. 5 parts by weight or less. When the content of the thermal radical curing agent is not less than the above lower limit and not more than the above upper limit, the anisotropic conductive paste is sufficiently cured by heat.

(Photocuring initiator)
The photocuring initiator is not particularly limited. A conventionally known photocuring initiator can be used as the photocuring initiator. As for the said photocuring initiator, only 1 type may be used and 2 or more types may be used together.

  The photocuring initiator is not particularly limited, and examples thereof include acetophenone photocuring initiator, benzophenone photocuring initiator, thioxanthone, ketal photocuring initiator, halogenated ketone, acyl phosphinoxide, and acyl phosphonate. .

  Specific examples of the acetophenone photocuring initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, methoxy Examples include acetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, and 2-hydroxy-2-cyclohexylacetophenone. Specific examples of the ketal photocuring initiator include benzyldimethyl ketal.

  The content of the photocuring initiator is not particularly limited. The content of the photocuring initiator is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, preferably 2 parts by weight or less, more preferably 100 parts by weight of the photocurable compound. Is 1 part by weight or less. When the content of the photocuring initiator is not less than the above lower limit and not more than the above upper limit, the anisotropic conductive paste is appropriately photocured. The anisotropic conductive paste can be prevented from flowing by irradiating the anisotropic conductive paste with light to form a B stage.

(Conductive particles)
The conductive particles contained in the anisotropic conductive paste electrically connect the flexible printed circuit board and the first and second electrodes of the connection target member. The conductive particles are not particularly limited as long as they are conductive particles. The surface of the conductive layer of the conductive particles may be covered with an insulating layer. In this case, the insulating layer between the conductive layer and the electrode is excluded when the flexible printed board and the connection target member are connected. Examples of the conductive particles include conductive particles obtained by coating the surfaces of organic particles, inorganic particles, organic-inorganic hybrid particles, or metal particles with a metal layer, and metal particles that are substantially composed of only metal. It is done. The metal layer is not particularly limited. Examples of the metal layer include a gold layer, a silver layer, a copper layer, a nickel layer, a palladium layer, and a metal layer containing tin.

  From the viewpoint of further improving the conduction reliability between the electrodes, the conductive particles preferably include resin particles and a conductive layer disposed on the surface of the resin particles.

  The average particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 100 μm or less, more preferably 20 μm or less, still more preferably 15 μm or less, and particularly preferably 10 μm or less.

  The “average particle size” of the conductive particles indicates a number average particle size. The average particle diameter of the conductive particles is determined by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating an average value.

  The content of the conductive particles is not particularly limited. The content of the conductive particles in 100% by weight of the anisotropic conductive paste is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, still more preferably 1% by weight or more, preferably 40% by weight. % Or less, more preferably 30% by weight or less, still more preferably 19% by weight or less. A conductive particle can be easily arrange | positioned between the upper and lower electrodes which should be connected as content of the said electroconductive particle is more than the said minimum and below the said upper limit. Furthermore, it becomes difficult to electrically connect adjacent electrodes that should not be connected via a plurality of conductive particles. That is, a short circuit between adjacent electrodes can be further prevented.

(Other ingredients)
The anisotropic conductive paste preferably contains a filler. By using the filler, the latent thermal expansion of the cured anisotropic conductive paste can be suppressed. Specific examples of the filler include silica, aluminum nitride, and alumina. As for the said filler, only 1 type may be used and 2 or more types may be used together.

  The anisotropic conductive paste preferably further contains a curing accelerator. Use of the curing accelerator further increases the curing rate of the anisotropic conductive paste. As for the said hardening accelerator, only 1 type may be used and 2 or more types may be used together.

  Specific examples of the curing accelerator include imidazole curing accelerators and amine curing accelerators. Of these, imidazole curing accelerators are preferred. In addition, an imidazole hardening accelerator or an amine hardening accelerator can be used also as an imidazole hardening agent or an amine hardening agent.

  The anisotropic conductive paste may contain a solvent. By using the solvent, the viscosity of the anisotropic conductive paste can be easily adjusted. Examples of the solvent include ethyl acetate, methyl cellosolve, toluene, acetone, methyl ethyl ketone, cyclohexane, n-hexane, tetrahydrofuran, and diethyl ether.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited only to the following examples.

Example 1
(1) Preparation of anisotropic conductive paste Bis (4-hydroxyphenyl) methane and 1,6-hexanediol diglycidyl ether are subjected to an addition polymerization reaction, whereby a skeleton derived from bis (4-hydroxyphenyl) methane and 1 , 6-hexanediol diglycidyl ether has a structural unit bonded with a skeleton derived from the main chain, and a reaction product having an epoxy group derived from 1,6-hexanediol diglycidyl ether at both ends was obtained. . Thereafter, acrylic acid was reacted to obtain an epoxy compound having an epoxy group at both ends and a vinyl group in the side chain.

  30 parts by weight of the resulting epoxy compound, 10 parts by weight of an amine adduct (“PN-23J” manufactured by Ajinomoto Fine Techno Co.) as a thermosetting agent, and an epoxy acrylate (“EBECRYL 3702 manufactured by Daicel Cytec Co., Ltd.) as a photocurable compound ”) 8 parts by weight, 0.2 part by weight of an acylphosphine oxide compound (“ DAROCUR TPO ”manufactured by Ciba Japan) as a photopolymerization initiator, and 2-ethyl-4-methylimidazole 1 as a curing accelerator Anisotropy that blends 20 parts by weight of silica, 20 parts by weight of silica with an average particle diameter of 0.25 μm and 20 parts by weight of alumina with an average particle diameter of 0.5 μm, and further provides conductive particles with an average particle diameter of 5 μm. After adding so that the content in 100% by weight of the conductive paste is 5% by weight, 2000 rp using a planetary stirrer In by stirring for 5 minutes, to obtain an anisotropic conductive paste.

  The conductive particles used are conductive particles having a metal layer in which a nickel plating layer is formed on the surface of divinylbenzene resin particles and a gold plating layer is formed on the surface of the nickel plating layer. is there.

(2) Fabrication of connection structure A semiconductor chip having a gold-plated Cu electrode pattern with L / S of 20 μm / 20 μm, length of 2 mm, and thickness of 10 μm on the surface, and length of 15 mm, width of 2 mm, and thickness of 800 μm A flexible printed circuit board on the surface was prepared. The flexible printed board has the Cu electrode pattern on the outer periphery of one end and the semiconductor chip in the center.

  Further, a glass substrate (member to be connected) having an aluminum electrode pattern with L / S of 20 μm / 20 μm, a length of 1 mm and a thickness of 0.3 μm on the surface was prepared. The glass substrate has the aluminum electrode pattern on the outer peripheral edge at one end.

  Also, a coating apparatus shown in FIG. The coating device includes a dispenser and an ultraviolet irradiation lamp that is a light irradiation device connected to the dispenser.

  The flexible printed circuit board was arranged so that the Cu electrode pattern and the semiconductor chip were positioned above. While moving the coating device on the Cu electrode pattern, an anisotropic conductive paste was applied to the surface of the flexible printed circuit board to form an anisotropic conductive paste layer. At this time, the anisotropic conductive paste was continuously applied linearly to the first application region on the electrode of the Cu electrode pattern and the second application region of the gap between the electrodes in the Cu electrode pattern. . At this time, the discharge amount of the anisotropic conductive paste from the dispenser is controlled so that the thickness of the anisotropic conductive paste layer portion disposed in the first application region on the electrode and the thickness between the plurality of electrodes are increased. The thickness of the anisotropic conductive paste layer portion disposed in the coating area 2 was set to the thickness shown in Table 1 below. The anisotropic conductive paste was not applied on the semiconductor chip of the flexible printed board.

Next, the anisotropic conductive paste layer is irradiated with ultraviolet rays using an ultraviolet irradiation lamp so that the irradiation energy is 6000 mJ / cm ^2, and the anisotropic conductive paste layer is semi-cured by photopolymerization to form a B stage. did. Next, the said Cu electrode pattern and the said aluminum electrode pattern were made to oppose, and the said flexible printed circuit board and the said glass substrate were laminated | stacked through the anisotropic conductive paste layer made into B stage. Then, while adjusting the temperature of the head so that the temperature of the B-staged anisotropic conductive paste layer becomes 185 ° C., a pressure heating head is placed on the upper surface of the glass substrate, and a pressure of 3 MPa is applied. The isotropic conductive paste layer was completely cured at 185 ° C. to obtain a connection structure.

(Examples 2 to 5)
The thickness of the anisotropic conductive paste layer portion disposed in the first application region on the electrode and the thickness of the anisotropic conductive paste layer portion disposed in the second application region between the plurality of electrodes were used. A connection structure was obtained in the same manner as in Example 1 except that the average particle diameter of the conductive particles was set to the thickness and average particle diameter shown in Table 1 below.

(Examples 6 to 8)
A flexible printed circuit board used for manufacturing a connection structure has a gold-plated Cu electrode pattern with L / S of 30 μm / 30 μm, a length of 2 mm, and a thickness of 30 μm on the surface, and a length of 15 mm, a width of 2 mm, and a thickness. Changed to a flexible printed circuit board having a semiconductor chip of 800 μm on the surface, and a member to be connected to a glass substrate having an aluminum electrode pattern on the surface with an L / S of 30 μm / 30 μm, a length of 1 mm, and a thickness of 0.3 μm The thickness of the anisotropic conductive paste layer portion disposed in the first application region on the electrode, and the anisotropic conductive paste layer portion disposed in the second application region between the plurality of electrodes. The connection structure is the same as in Example 1 except that the thickness and the average particle diameter of the conductive particles are set to the thickness and average particle diameter shown in Table 1 below. It was obtained.

Example 9
When preparing the anisotropic conductive paste, 8 parts by weight of epoxy acrylate (“EBECRYL 3702”, manufactured by Daicel-Cytec), which is a photocurable compound, and urethane acrylate (“EBECRYL8804, manufactured by Daicel-Cytec, Inc.), which is a photocurable compound, are used. ]) An anisotropic conductive paste was obtained in the same manner as in Example 1 except that the amount was changed to 8 parts by weight. Further, the use of the obtained anisotropic conductive paste, the thickness of the anisotropic conductive paste layer portion disposed in the first application region on the electrode, and the second application region between the plurality of electrodes Except for setting the thickness of the disposed anisotropic conductive paste layer portion and the average particle size of the conductive particles used to the thickness and average particle size shown in Table 1 below, the same as in Example 1. A connection structure was obtained.

(Comparative Example 1)
The same flexible printed circuit board and glass substrate as Example 1 were prepared.

  An anisotropic conductive paste layer was formed by applying an anisotropic conductive paste to the surface of the flexible printed board using a screen printing plate without using a dispenser. At this time, the anisotropic conductive paste was applied to the same first and second application regions as in Example 1.

  Thereafter, in the same manner as in Example 1, the anisotropic conductive paste layer was B-staged and fully cured to obtain a connection structure.

(Evaluation)
(1) Viscosity η1 and viscosity ratio (η2 / η3)
Using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.), the viscosity η1 of the obtained anisotropic conductive paste (viscosity of the anisotropic conductive paste before application) was measured at 25 ° C. and 2.5 rpm. did. Moreover, the viscosity η2 at 25 ° C. and 2.5 rpm and the viscosity η3 at 25 ° C. and 5 rpm were measured using the E-type viscometer.

(2) Presence / absence of voids 100 connection structures in Examples and Comparative Examples were prepared. In the obtained connection structure, whether or not voids were generated in the cured product layer formed of the anisotropic conductive paste layer was visually observed from the lower surface side of the transparent glass substrate. The presence or absence of voids was determined according to the following criteria. When there is a void, the conduction reliability in the connection structure is lowered.

[Criteria for the presence or absence of voids]
○○: No void in all 100 connection structures ○: Although there are connection structures with voids having a maximum length of 10 μm or less in 100 connection structures, all connection structures are Usable △: Among 100 connection structures, there are connection structures with voids whose maximum length exceeds 10 μm and 30 μm or less, but all connection structures can be used ×: 100 connection structures There is a connection structure with a maximum length exceeding 30 μm in the body.

(3) Presence / absence of displacement between electrode of flexible printed circuit board and electrode of glass substrate 100 connection structures in Examples and Comparative Examples were prepared. In the obtained connection structure, it was evaluated whether or not a positional deviation occurred between the electrode of the flexible printed board and the electrode of the glass substrate. The positional deviation was determined according to the following criteria.

[Criteria for misalignment]
○○: There is no displacement between electrodes in all 100 connection structures, or the displacement width between electrodes is 2 μm or less. ○: The displacement width between electrodes exceeds 2 μm in 100 connection structures. All connection structures can be used even though there is a connection structure that is 5 μm or less. Δ: Among 100 connection structures, there is a connection structure in which the displacement width between electrodes exceeds 5 μm and is 10 μm or less. However, all connection structures can be used. X: Among 100 connection structures, there is a connection structure exceeding a displacement width of 10 μm between electrodes.

(4) Conduction reliability (conductivity test between upper and lower electrodes)
The connection resistance between the upper and lower electrodes of the obtained connection structure was measured by a four-terminal method. The average value of the connection resistance at 100 locations was calculated. Note that the connection resistance can be obtained by measuring the voltage when a constant current is passed from the relationship of voltage = current × resistance. The case where the average value of the connection resistance was 3Ω or less was judged as “◯”, and the case where the average value of the connection resistance exceeded 3Ω was judged as “X”.

  The results are shown in Table 1 below. In addition, when the state of the upper surface of the anisotropic conductive paste layer is smooth, the upper surface of the anisotropic conductive paste layer portion arranged in the first application region and the anisotropic arranged in the second application region The conductive conductive paste layer portion was smooth so as to be continuous with the upper surface. In addition, all the conductive particles used in the examples and comparative examples are metals in which a nickel plating layer is formed on the surface of the divinylbenzene resin particles, and a gold plating layer is formed on the surface of the nickel plating layer. A conductive particle having a layer.

DESCRIPTION OF SYMBOLS 1 ... Connection structure 2 ... Connection object member 2a ... Surface 2b ... 2nd electrode 3 ... Hardened | cured material layer 3a ... Upper surface 3A ... Anisotropic conductive paste layer 3B ... An anisotropic conductive paste layer made into B stage 4 ... Flexible printed circuit board 4a ... surface 4b ... first electrode 4c ... electronic component 5 ... conductive particles 11 ... coating device 12 ... dispenser 12a ... syringe 12b ... gripping part 12c ... tip 13 ... light irradiation device 13a ... light irradiation device body 13b ... Light irradiation unit 21 ... Light irradiation device 21a ... Light irradiation device body 21b ... Light irradiation unit 31 ... Stand 61 ... Flexible printed circuit board 61a ... Surface 61b ... First electrode 61c ... Electronic component

Claims (9)

A flexible printed circuit board having a protruding first electrode on its surface and a protruding electronic component having a protruding height larger than that of the first electrode on the surface is used. Disposing an anisotropic conductive paste layer in the first application region on the electrode using an anisotropic conductive paste containing a curable component and conductive particles;
Using the connection target member having the second electrode on the surface, the first electrode and the second electrode are opposed to each other, and the flexible printed circuit board and the connection target member are connected to the anisotropic conductive paste. Laminating through layers;
Curing the anisotropic conductive paste layer to form a cured product layer,
In the step of disposing the anisotropic conductive paste layer, the anisotropic conductive paste is applied from the dispenser while moving the dispenser.   2. The connection structure according to claim 1, wherein in the step of disposing the anisotropic conductive paste layer, the anisotropic conductive paste layer is also disposed in a second application region that is not on the first electrode. Production method. The flexible printed circuit board includes a plurality of the first electrodes, and the connection target member includes a plurality of the second electrodes;
The method for manufacturing a connection structure according to claim 2, wherein the second application region includes a region of a gap between the plurality of first electrodes.   The method for manufacturing a connection structure according to claim 2 or 3, wherein a surface of the second application region of the flexible printed board does not protrude or has a protruding height smaller than that of the first electrode.   The method for manufacturing a connection structure according to claim 4, wherein a surface of the second application region of the flexible printed board does not protrude.   In the step of disposing the anisotropic conductive paste layer, the thickness of the anisotropic conductive paste layer portion disposed in the first application region on the first electrode is not on the first electrode. The manufacturing method of the connection structure of any one of Claims 2-5 made thinner than the thickness of the said anisotropic conductive paste layer part arrange | positioned at a said 2nd application | coating area | region.   In the step of disposing the anisotropic conductive paste layer, the upper surface of the anisotropic conductive paste layer portion disposed in the first application region on the first electrode and not on the first electrode The manufacturing method of the connection structure of any one of Claims 2-6 which makes it smooth so that the upper surface of the said anisotropic conductive paste layer part arrange | positioned in a 2nd application | coating area may be continued.   In the step of disposing the anisotropic conductive paste layer, the anisotropic conductive paste includes the thickness of the anisotropic conductive paste layer portion disposed in the first application region on the first electrode. The manufacturing method of the connection structure of any one of Claims 1-7 which makes it 3 times or more of the average particle diameter of the said electrically-conductive particle. The flexible printed circuit board includes a plurality of the first electrodes, and the connection target member includes a plurality of the second electrodes;
The height of the first electrode is 5 μm or more, and the gap between the plurality of first electrodes is 30 μm or less;
The anisotropic conductive paste has a viscosity at 25 ° C. and 2.5 rpm of more than 200 Pa · s and not more than 800 Pa · s, and a viscosity ratio of 25 ° C. and 2.5 rpm to 25 ° C. and 5 rpm. The manufacturing method of the connection structure of any one of Claims 1-8 using the anisotropic conductive paste whose 1 is 2 or more.

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