TW201535418A - Connection structure manufacturing method - Google Patents

Abstract

Provided is a connection structure manufacturing method by which it is possible to efficiently dispose solder particles on electrodes and by which it is possible to increase conduction reliability between the electrodes. This connection structure manufacturing method comprises: a step for disposing a conductive paste on a surface of a first member to be connected, said conductive paste containing a plurality of solder particles and a thermosetting component; a step for disposing a second member to be connected on the reverse surface of the conductive paste from the first member to be connected side in a manner such that a first electrode and a second electrode oppose one another; and a step for forming a connection part from the conductive paste by heating the conductive paste, said connection part connecting the first member to be connected and the second member to be connected. In the step for disposing the second member to be connected and the step for forming the connection part, the weight of the second member to be connected is applied to the conductive paste without the application of pressure.

Description

Manufacturing method of connecting structure

The present invention relates to a method of manufacturing a bonded structure in which electrodes are electrically connected by solder particles.

Anisotropic conductive materials such as anisotropic conductive pastes and anisotropic conductive films are widely known. In the anisotropic conductive material described above, conductive particles are dispersed in the binder resin.

In order to obtain various connection structures, the anisotropic conductive material is used for, for example, a connection between a flexible printed substrate and a glass substrate (FOG (Film on Glass)), and a connection between a semiconductor wafer and a flexible printed substrate (COF (Chip) On film, film flip chip), connection between semiconductor wafer and glass substrate (COG (Chip on Glass)), and connection between flexible printed substrate and epoxy glass substrate (FOB (Film on Board) )Wait.

When the electrode of the flexible printed circuit board and the electrode of the epoxy glass substrate are electrically connected by the anisotropic conductive material, the anisotropic conductive material containing the conductive particles is placed on the epoxy glass substrate. Next, a flexible printed circuit board is laminated and heated and pressurized. Thereby, the anisotropic conductive material is cured, and the electrodes are electrically connected via the conductive particles to obtain a bonded structure.

As an example of the anisotropic conductive material, Patent Document 1 discloses a resin layer containing a thermosetting resin, a solder powder, and a curing agent, and the solder powder and the curing agent are present in the resin layer. Then bring it. The subsequent strip is membranous, not paste shape.

Further, Patent Document 1 discloses a method of using the above-described subsequent tape. Specifically, the first substrate, the subsequent tape, the second substrate, the adhesive tape, and the third substrate are sequentially laminated from the bottom to the top to obtain a laminate. At this time, the first electrode provided on the surface of the first substrate is opposed to the second electrode provided on the surface of the second substrate. Further, the second electrode provided on the surface of the second substrate faces the third electrode provided on the surface of the third substrate. Then, the laminate is heated at a specific temperature and then. Thereby, the connection structure is obtained.

Further, in Patent Document 1, it is preferable to pressurize the solder powder to flow on the surface of the electrode and efficiently move it at a specific pressure in the subsequent step, and it is described that it is formed more reliably. From the viewpoint of the solder region, the pressurizing pressure is, for example, 0 MPa or more, preferably 1 MPa or more, and further described that the pressure applied to the subsequent tape may be 0 MPa or may be disposed on the member under the tape. The weight of the self exerts a specific pressure on the belt.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] WO2008/023452A1

The adhesive tape described in Patent Document 1 is in the form of a film rather than a paste. Therefore, it is difficult to efficiently arrange the solder powder on the electrodes (lines). For example, in the adhesive tape described in Patent Document 1, it is also easy to arrange one of the solder powders in a region (interval) where no electrode is formed. The solder powder disposed in the region where the electrode is not formed does not contribute to conduction between the electrodes.

Further, Patent Document 1 discloses that the pressure to be intentionally applied to the subsequent tape may be 0 MPa, but there is no description about the difference between the effect of applying a pressure exceeding 0 MPa and the case of setting it to 0 MPa.

It is an object of the present invention to provide a solder particle that can be efficiently disposed on an electrode Further, a method of manufacturing a connection structure capable of improving the conduction reliability between electrodes can be achieved.

According to a broad aspect of the present invention, a method of manufacturing a connection structure comprising: using a conductive paste containing a plurality of solder particles and a thermosetting component, and having a first connection member having at least one first electrode on a surface thereof a step of disposing the conductive paste on the surface; and a second connection member having at least one second electrode on the surface thereof, wherein the first electrode and the second electrode face each other and are disposed on the first connection of the conductive paste a step of forming the first connection member and the above-described conductive paste by heating the conductive paste to a temperature equal to or higher than a melting point of the solder particles and a hardening temperature of the thermosetting component. a step of connecting the connection member of the second connection target member, and in the step of arranging the second connection target member and forming the connection portion, applying the weight of the second connection target member to the conductive paste without applying pressure .

In a specific aspect of the method for producing a connection structure according to the present invention, the second connection member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate.

In a specific aspect of the method for producing a connection structure according to the present invention, the distance between the first electrode and the second electrode facing the connection portion is set to be 3 μm or more and 40 μm or less.

In a specific aspect of the method for producing a connection structure according to the present invention, in the connection portion, a size of a portion facing the first electrode and the second electrode is the first electrode and the second electrode The size of the unopposed part is 2 times or more and 40 times or less.

In a specific aspect of the conductive paste of the present invention, the viscosity at 25 ° C is 10 Pa ‧ or more and 800 Pa ‧ or less.

In a specific aspect of the conductive paste of the present invention, the minimum value of the viscosity under the temperature range below the melting point of the solder particles is 0.1 Pa ‧ s or more, 10 Pa ‧ s under.

In a specific aspect of the method for producing a connection structure according to the present invention, the connection portion has a corner portion, and the first connection member has a first electrode for alignment on the inside of the corner portion as the first electrode. The second connection member has a second electrode for alignment on the inner side of the corner portion as the second electrode, and the first electrode for alignment and the second electrode for alignment and the front end of the corner portion The shortest distance is 75 μm or more and 3000 μm or less.

In a specific aspect of the method for producing a connection structure according to the present invention, the first connection member has a plurality of first main electrodes having a longitudinal direction and a width direction as the first electrode, and the second connection member has a plurality of second main electrodes having a longitudinal direction and a width direction as the second electrode, and a linear expansion ratio of the first connection member in the longitudinal direction and the width direction of the first main electrode and the second main electrode The difference in linear expansion ratio of the second connection member in the longitudinal direction and the width direction is C (ppm/° C.), and the heating temperature of the conductive paste when the connection portion is formed is T (° C.). The size of the plurality of first main electrodes in the width direction of the first main electrode is Yt (mm), and the size of each of the plurality of first main electrodes in the width direction is Ya (mm) When satisfied, the formula: C × T / 1000000 × Yt < 0.5 × Ya.

The method for producing a connection structure according to the present invention includes the step of disposing the conductive paste on the surface of the first connection member having at least one first electrode on the surface thereof by using a conductive paste containing a plurality of solder particles and a thermosetting component. And the second connection member having at least one second electrode on the surface thereof is disposed on the surface of the conductive paste opposite to the first connection member side so that the first electrode and the second electrode face each other By heating the conductive paste to a temperature equal to or higher than a melting point of the solder particles and a curing temperature of the thermosetting component, a connection portion connecting the first connection member and the second connection member is formed by the conductive paste. Step; and configuring the second connection described above In the step of forming the target member and the step of forming the connecting portion, the weight of the second connection member is applied to the conductive paste without applying pressure, so that the solder particles can be efficiently disposed on the electrode, and the electrode can be improved. Continuity reliability.

1‧‧‧Connection structure

1X‧‧‧Connection structure

2‧‧‧1st connection object component

2a‧‧‧1st electrode

3‧‧‧2nd connection object component

3a‧‧‧2nd electrode

4‧‧‧Connecting Department

4A‧‧‧ solder department

4B‧‧‧ Hardened Parts

4X‧‧‧Connecting Department

4XA‧‧‧ solder department

4XB‧‧‧ Hardened Parts Department

11‧‧‧Electric paste

11A‧‧‧ solder particles

11B‧‧‧ thermosetting ingredients

51‧‧‧Connection structure

51X‧‧‧Connection structure

51Y‧‧‧Connection structure

52‧‧‧1st connection object component

52a‧‧‧1st electrode

52aa‧‧‧1st electrode for position alignment

52ab‧‧‧1st main electrode

52X‧‧‧1st connection object component

52Y‧‧‧1st connection object component

53‧‧‧2nd connection object component

53a‧‧‧2nd electrode

53aa‧‧‧2nd electrode for position alignment

53ab‧‧‧2nd main electrode

53X‧‧‧2nd connection object component

53Y‧‧‧2nd connection object component

54‧‧‧Connecting Department

54A‧‧‧ solder department

54B‧‧‧ Hardened Parts

54X‧‧‧Connecting Department

54XA‧‧‧ solder department

54XB‧‧‧ Hardened Parts

54Y‧‧‧Connecting Department

54YA‧‧‧ solder department

54YB‧‧‧ Hardened Parts

C‧‧‧ corner

Yt‧‧‧1st main electrode size

Ya‧‧‧Dimensions of each electrode of the 1st main electrode in the width direction

Fig. 1 is a partially cutaway front elevational cross-sectional view schematically showing a connection structure obtained by a method of manufacturing a connection structure according to an embodiment of the present invention.

2(a) to 2(c) are cross-sectional views for explaining respective steps of a method of manufacturing a connection structure according to an embodiment of the present invention.

Fig. 3(a) is a plan view showing a variation of the connection structure, and Fig. 3(b) is a cross-sectional view taken along line I-I of Fig. 3(a).

Fig. 4(a) is a plan view showing a variation of the connection structure, Fig. 4(b) is a cross-sectional view taken along line II of Fig. 4(a), and Fig. 4(c) is taken along line II-II of Fig. 4(a). A cross-sectional view of the line.

Fig. 5(a) is a plan view showing a variation of the connection structure, and Fig. 5(b) is a cross-sectional view taken along line I-I of Fig. 5(a).

Fig. 6 is a partial front elevational cross-sectional view showing a variation of the connection structure.

7(a), 7(b) and 7(c) are views showing an example of a connection structure included in an embodiment of the present invention, and Figs. 7(a) and (b) are cross-sectional images, and Fig. 7(c) ) is a flat image.

8(a), (b) and (c) are views showing an example of a connection structure not included in the embodiment of the present invention, and Figs. 8(a) and (b) are cross-sectional images, and Fig. 8(c) ) is a flat image.

Hereinafter, the details of the present invention will be described.

In the method of manufacturing the connection structure of the present invention, the conductive paste, the first connection member, and the second connection member are used. The conductive material used in the method for producing the bonded structure of the present invention is a conductive paste instead of a conductive film. The conductive paste contains a plurality of solder particles and a thermosetting component. The first connection target member has at least one first electrode on the surface. The second connection target member has at least one second electrode on the surface.

The method for manufacturing a connection structure according to the present invention includes the steps of: disposing the conductive paste on a surface of the first connection member; and facing the second connection member with the first electrode and the second electrode And a step of disposing the conductive paste on a surface opposite to the first connection target member side; and heating the conductive paste to a temperature higher than a melting point of the solder particles and a hardening temperature of the thermosetting component The conductive paste forms a step of connecting a connection portion between the first connection target member and the second connection target member. In the method of manufacturing the connection structure of the present invention, in the step of disposing the second connection member and the step of forming the connection portion, the weight of the second connection member is applied to the conductive paste without applying pressure. . In the method of manufacturing the connection structure of the present invention, in the step of disposing the second connection member and the step of forming the connection portion, the conductive paste is not subjected to a force exceeding the weight of the second connection member. Pressurized pressure.

In the method for manufacturing a connection structure according to the present invention, since the plurality of solder particles are easily collected between the first electrode and the second electrode, a plurality of solder particles can be efficiently disposed on the electrode (line). )on. Further, it is difficult to arrange one of the plurality of solder particles in a region (interval) in which the electrode is not formed, and the amount of the solder particles disposed in the region where the electrode is not formed can be extremely small. Therefore, the conduction reliability between the first electrode and the second electrode can be improved. Moreover, the electrical connection between the electrodes adjacent to each other that are not connectable can be prevented, and the insulation reliability can be improved.

As described above, the inventors of the present invention have found that in order to efficiently arrange a plurality of solder particles on an electrode and to have a very small amount of solder particles disposed in a region where no electrode is formed, it is necessary to use a conductive paste instead of conductive. membrane. Furthermore, the inventors of the present invention have found that, in the step of arranging the second connection member and the step of forming the connection portion, if the weight of the second connection member is applied to the conductive paste without applying pressure, The solder particles disposed in the region (interval) where the electrode is not formed before the formation of the connection portion are further easily collected between the first electrode and the second electrode, and the plurality of solder particles can be efficiently matched Place on the electrode (line). In the present invention, a configuration in which a conductive paste is used instead of a conductive film and a structure in which the weight of the second connection member is applied to the conductive paste without pressurization is used in combination, and the effect of the present invention is large. The meaning.

Further, when a conductive paste is used instead of the conductive film, the thickness of the joint portion can be appropriately adjusted depending on the amount of the conductive paste applied. On the other hand, the conductive film has a problem that in order to change or adjust the thickness of the connection portion, it is necessary to prepare a conductive film of a different thickness or prepare a conductive film of a specific thickness.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the specific embodiments and embodiments of the invention.

First, a connection structure obtained by a method of manufacturing a connection structure according to an embodiment of the present invention is schematically shown in a partial defect front view in FIG.

The connection structure 1 shown in FIG. 1 includes a first connection object member 2, a second connection object member 3, and a connection portion 4 that connects the first connection object member 2 and the second connection object member 3. The connecting portion 4 is formed by a conductive paste containing a plurality of solder particles and a thermosetting component. The connection portion 4 has a solder portion 4A in which a plurality of solder particles are aggregated and joined to each other, and a cured portion 4B in which a thermosetting component is thermally cured.

The first connection target member 2 has a plurality of first electrodes 2a on the surface (upper surface). The second connection target member 3 has a plurality of second electrodes 3a on the front surface (lower surface). The first electrode 2a and the second electrode 3a are electrically connected by the solder portion 4A. Therefore, the first connection object member 2 and the second connection object member 3 are electrically connected by the solder portion 4A. Further, in the connection portion 4, solder is not present in a region (a portion of the cured portion 4B) different from the solder portion 4A collected between the first electrode 2a and the second electrode 3a. There is no solder separated from the solder portion 4A in a region different from the solder portion 4A (the portion of the cured portion 4B). In addition, in a small amount, solder may be present in a region (a portion of the cured portion 4B) different from the solder portion 4A collected between the first electrode 2a and the second electrode 3a.

As shown in FIG. 1, in the connection structure 1, after a plurality of solder particles are melted, the solder The melt of the particles is wet-diffused on the surface of the electrode and then solidified to form the solder portion 4A. Therefore, the connection area between the solder portion 4A and the first electrode 2a and the solder portion 4A and the second electrode 3a is increased. In other words, by using the solder particles, the solder portion 4A and the first electrode 2a, and the solder portion 4A and the second electrode 3a are used as compared with the case where the conductive outer surface is a conductive particle of a metal such as nickel, gold or copper. The contact area is increased. Therefore, the connection reliability and connection reliability of the connection structure 1 are improved. Further, the conductive paste may also contain a flux. In the case of flux, the flux is usually deactivated by heating.

Further, in the connection structure 1 shown in Fig. 1, the solder portions 4A are all located in the opposing regions between the first and second electrodes 2a and 3a. In the connection structure 1X of the variation shown in Fig. 6, only the connection portion 4X is different from the connection structure 1 shown in Fig. 1 . The connecting portion 4X has a solder portion 4XA and a cured portion 4XB. As in the connection structure 1X, most of the solder portion 4XA may be located in a region where the first and second electrodes 2a and 3a face each other, and a portion of the solder portion 4XA may be opposed to the first and second electrodes 2a and 3a. The area extends laterally. A portion of the solder portion 4XA-based solder portion 4XA that protrudes laterally from the region in which the first and second electrodes 2a and 3a face each other is not solder separated from the solder portion 4XA. Further, in the present embodiment, the amount of solder separated from the solder portion may be small, but the solder separated from the solder portion may be present in the cured portion.

When the amount of use of the solder particles is reduced, the connection structure 1 is easily obtained. When the amount of use of the solder particles is increased, the connection structure 1X is easily obtained.

Next, a method of manufacturing a joint structure according to an embodiment of the present invention for obtaining the joint structure 1 shown in Fig. 1 will be described.

First, the first connection target member 2 having the first electrode 2a on the front surface (upper surface) is prepared. Next, as shown in FIG. 2(a), a conductive paste 11 containing a plurality of solder particles 11A and a thermosetting component 11B is placed on the surface of the first connection member 2 (first step). The conductive paste 11 is placed on the surface of the first connection member 2 on which the first electrode 2a is provided. After the conductive paste 11 is disposed, the solder particles 11A are disposed on the first electrode 2a (line) and the first electrode 2a is not formed. Both of the areas (intervals).

The method of disposing the conductive paste 11 is not particularly limited, and examples thereof include coating by a dispenser, screen printing, and ejection by an inkjet device.

Moreover, the second connection member 3 having the second electrode 3a on the front surface (lower surface) is prepared. Next, as shown in FIG. 2(b), in the conductive paste 11 on the surface of the first connection member 2, the second connection is placed on the surface of the conductive paste 11 on the side opposite to the first connection target member 2 side. Target member 3 (second step). The second connection member 3 is placed on the surface of the conductive paste 11 from the second electrode 3a side. At this time, the first electrode 2a and the second electrode 3a are opposed to each other.

Next, the conductive paste 11 is heated to a temperature equal to or higher than the melting point of the solder particles 11A and the hardening temperature of the thermosetting component 11B (third step). That is, the conductive paste 11 is heated to a temperature at which the melting point of the solder particles 11A and the hardening temperature of the thermosetting component 11B are relatively low. At the time of this heating, the solder particles 11A existing in the region where the electrode is not formed are collected between the first electrode 2a and the second electrode 3a (self-aggregation effect). In the present embodiment, since the conductive paste is used instead of the conductive film, the solder particles 11A are effectively collected between the first electrode 2a and the second electrode 3a. Further, the solder particles 11A are melted and joined to each other. Further, the thermosetting component 11B is thermally cured. As a result, as shown in FIG. 2( c ), the connection portion 4 that connects the first connection target member 2 and the second connection target member 3 is formed by the conductive paste 11 . The connection portion 4 is formed by the conductive paste 11, and the solder portion 4A is joined by a plurality of solder particles 11A, and is thermally cured by the thermosetting component 11B to form the cured portion 4B. When the solder particles 11A move rapidly, the solder particles 11A that are not located between the first electrode 2a and the second electrode 3a start to move until the movement of the solder particles 11A between the first electrode 2a and the second electrode 3a is completed. It is also possible not to keep the temperature fixed.

Further, a preheating step may be provided in the first half of the third step. In the state in which the weight of the second connection member 3 is applied to the conductive paste 11, the temperature is not higher than the melting temperature of the solder, and the thermosetting component 11B is not thermally cured for 5 seconds. The step of heating up to 60 seconds. By setting this step, the solder particles are concentrated on The action between the first electrode and the second electrode is further improved, and the pores which may be generated between the first connection member and the second connection member can be suppressed.

In the present embodiment, no pressurization is performed in the second step and the third step. In the present embodiment, the weight of the second connection member 3 is applied to the conductive paste 11. Therefore, when the connection portion 4 is formed, the solder particles 11A are effectively collected between the first electrode 2a and the second electrode 3a. Further, when pressurization is performed in at least one of the second step and the third step, the action of collecting the solder particles between the first electrode and the second electrode is inhibited. This situation was discovered by the inventors and the like.

Thus, the connection structure 1 shown in Fig. 1 is obtained. Furthermore, the second step and the third step described above can be continuously performed. Further, after the second step, the obtained first connection member 2 and the laminated body of the conductive paste 11 and the second connection member 3 may be moved to the heating unit, and the third step may be performed. In order to perform the above heating, the laminated body may be disposed on the heating member, or the laminated body may be disposed in the heated space.

From the viewpoint of further improving the conduction reliability, it is preferable to obtain the connection structures 1 and 1X as follows, that is, in the connection structures 1 and 1X, along the first electrode 2a, the connection portion 4, and the second electrode. When the first electrode 2a and the second electrode 3a are opposed to each other in the direction of the lamination of the layer 3a, the connection portion is disposed at 50% or more of the area of the mutually opposing portions of the first electrode 2a and the second electrode 3a. 4, 4X solder parts 4A, 4XA.

The heating temperature in the third step is not particularly limited as long as it is equal to or higher than the melting point of the solder particles and the curing temperature of the thermosetting component. The heating temperature is preferably 130 ° C or higher, more preferably 160 ° C or higher, and is preferably 450 ° C or lower, more preferably 250 ° C or lower, and still more preferably 200 ° C or lower.

The temperature of the preheating step is preferably 100 ° C or more, more preferably 120 ° C or more, further preferably 140 ° C or more, and preferably less than 160 ° C, more preferably 150 ° C or less.

Further, the first connection target member may have at least one first electrode. Preferably, the first connection target member has a plurality of first electrodes. The second connection object member There is at least one second electrode. Preferably, the second connection target member has a plurality of second electrodes.

The first and second connection target members are not particularly limited. Specific examples of the first and second connection target members include electronic components such as semiconductor wafers, capacitors, and diodes; and resin films, printed boards, flexible printed boards, flexible flat cables, rigid flexible substrates, and rings. Electronic components such as circuit boards such as an oxygen glass substrate and a glass substrate. The first and second connection target members are preferably electronic components.

At least one of the first connection target member and the second connection target member is preferably a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate. Preferably, the second connection member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate. The resin film, the flexible printed circuit board, the flexible flat cable, and the rigid flexible substrate have high flexibility and relatively lightweight properties. When a conductive film is used for the connection of such a connection target member, there is a tendency that solder particles are less likely to accumulate on the electrode. On the other hand, in the present invention, since a conductive paste is used, even if a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate is used, solder particles can be efficiently collected on the electrodes, and the electrodes can be sufficiently increased. Continuity reliability. When a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate is used, it is possible to more effectively obtain conduction between electrodes due to no pressurization as compared with the case of using other connection member such as a semiconductor wafer. Increased reliability. The first and second connection target members may be a resin film, a flexible printed circuit board, or a flexible flat cable, or may be a rigid flexible substrate.

Examples of the electrode provided in the connection target member include metal electrodes such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a copper electrode, a silver electrode, a molybdenum electrode, a SUS electrode, and a tungsten electrode. In the case where the connection target member is a flexible printed circuit board or a flexible flat cable, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, a silver electrode or a copper electrode. In the case where the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode or a tungsten electrode. Furthermore, the above electrode is an aluminum electrode In the case of the electrode, it may be an electrode formed only of aluminum, or an electrode having an aluminum layer on the surface layer of the metal oxide layer. Examples of the material of the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, Ga, and the like.

The distance D1 of the connecting portion at a position where the first electrode and the second electrode face each other is preferably 3 μm or more, more preferably 5 μm or more, and is preferably 40 μm or less, and more preferably 30 μm or less. When the distance D1 is equal to or higher than the lower limit, the connection reliability between the connection portion and the connection target member is further improved. When the distance D1 is equal to or less than the above upper limit, the solder particles are more likely to accumulate on the electrode when the connection portion is formed, and the conduction reliability between the electrodes is further improved. Moreover, the distance D1 is preferably 10 μm or more, and more preferably 12 μm or more from the viewpoint of further improving the conduction reliability between the electrodes.

In the connection portion, the size S1 of the portion facing the first electrode and the second electrode (for example, the hatched portions in FIGS. 3(a) and 4(a)) is preferably the first electrode and the first portion. The size S2 of the portion where the two electrodes are not opposed (for example, the points of FIG. 3(a) and FIG. 4(a)) is twice or more, more preferably 10 times or more, and preferably 40 times or less, more preferably It is 30 times or less. The size S1 and the size S2 are the sizes when the structure is connected in a plan view. The size S1 is an area of a region where the first electrode overlaps the second electrode when the connection structure is viewed in plan. The size S2 is an area of a region where the first electrode and the second electrode do not overlap when the connection structure is viewed in plan. The size S2 is a size obtained by removing the size S1 from the size of the entire connecting portion.

Next, a modification of the connection structure will be described.

3(a) and 3(b) show a connection structure 51 as a modification. Fig. 3(a) is a plan view, and Fig. 3(b) is a cross-sectional view taken along line I-I.

As in the connection structure 51 shown in FIGS. 3(a) and 3(b), the connecting portion 54 preferably has a corner portion C. In FIGS. 3(a) and 3(b), the connecting portion 54 has four corner portions C in the main surface direction. The corner portion C is, for example, a portion where the two sides of the connecting portion 54 intersect. Preferably, the first connection object member 52 is The first electrode 52aa for alignment is provided on the inner side of the corner portion C as the first electrode 52a. It is preferable that the second connection target member 53 has the second electrode 53aa for alignment on the inner side of the corner portion C as the second electrode 53a. When such an electrode for alignment is provided, when the solder particles are collected between the first electrode 52aa for alignment and the second electrode 53aa for alignment, they can function to prevent alignment. The positional deviation between the first electrode 52aa and the second electrode 53aa for alignment is eliminated, and the positional deviation generated thereby is eliminated (for example, FIG. 7(a) of the embodiment of the present invention and a form not included in the embodiment of the present invention. Figure 8 (a) difference). Therefore, the conduction reliability between the electrodes is improved.

In FIG. 3(b), the first electrode 52a and the second electrode 53a include one or more electrodes. The first electrode 52a and the second electrode 53a are preferably two or more electrodes having a pattern of a face array of comb-shaped, zigzag-shaped, dot or four-corner electrodes. In this case, the pattern of the first electrode 52a and the second electrode 53a is preferably such that the patterns coincide with each other. In the case of two or more electrodes, the distance between the electrodes is preferably 75 μm or more, more preferably 100 μm or more, and is preferably 2 mm or less, more preferably 1 mm or less. The length of the electrode is preferably 200 μm or more, more preferably 1 mm or more, and is preferably 5 mm or less, more preferably 3 mm or less.

Further, in FIGS. 3(a) and 3(b), a partial region of the second connection target member 53 is superposed on the first connection target member 52. The first electrode 52a (main electrode) and the second electrode 53a (main electrode) that are electrically connected by the solder portion 54A are opposed to each other in the central region of the overlapping portion between the first connection target member 52 and the second connection target member 53. The way it is configured. In Fig. 3(a), in the vicinity of the two corner portions C of the connecting portion 54 corresponding to the two corner portions of the distal end of the second connecting member 53, two first electrodes 52aa for alignment and two position pairs are provided. The second electrode 53aa to be used is disposed to face each other. The first electrode 52aa for alignment and the second electrode 53aa for alignment are electrically connected by the solder portion 54A. The cured portion 54B is located around the solder portion 54A.

The size of the first electrode 52aa and the second electrode 53aa is preferably 300 μm or more, more preferably 500 μm or more, and the shape of the first electrode 52aa and the second electrode 53aa may be positive. Square, rectangular, round, oval.

The first electrode 52aa and the second electrode 53aa can be used only for alignment, and can also be used as an electrode for a power source requiring a large electrode area.

The shortest distance between the first electrode for alignment and the second electrode for alignment and the front end of the corner is preferably 75 μm or more and 3000 μm or less from the viewpoint of facilitating alignment.

4(a) and 4(b) show a connection structure 51X as a modification. 4(a) is a plan view, FIG. 4(b) is a cross-sectional view taken along line I-I, and FIG. 4(c) is a cross-sectional view taken along line II-II.

In FIGS. 4(a) and 4(b), the two corner portions C including the two corner portions of the distal end of the second connection member 53X and the other two corner portions C are included. In the vicinity of the corner portion C, the first electrode 52aa for alignment of the four positions and the second electrode 53aa for alignment of the four positions are disposed to face each other. As described above, the four first and second electrodes 52aa and 53aa for alignment may be disposed in the vicinity of the four corner portions C. The first electrode 52aa for alignment and the second electrode 53aa for alignment are electrically connected by the solder portion 54XA. The cured portion 54XB is located around the solder portion 54XA.

5(a) and 5(b) show a connection structure 51Y as a modification. Fig. 5(a) is a plan view, and Fig. 5(b) is a cross-sectional view taken along line I-I.

In the connection structure 51Y, the positional displacement between the upper and lower electrodes caused by thermal expansion when the first connection member 52Y and the second connection target member 53Y are heated is suppressed, and the conduction reliability is further improved. It is preferable that the first connection target member 52Y has a plurality of first main electrodes 52ab having a longitudinal direction and a width direction as the first electrode 52a, and the second connection target member 53Y has a plurality of second main electrodes having a longitudinal direction and a width direction. 53ab is the second electrode 53a, and the second expansion ratio of the first connection target member 52Y in the longitudinal direction and the width direction of the first main electrode 52ab is the second connection in the longitudinal direction and the width direction of the second main electrode 53ab. The difference in linear expansion coefficient of the target member 53Y is C (ppm/° C.), and the heating temperature of the conductive paste when the connecting portion 54Y is formed is T (° C.), and the first When the size of the entire plurality of first main electrodes 52ab in the width direction of the main electrode 52ab is Yt (mm), and the size of each of the plurality of first main electrodes 52ab in the width direction is Ya (mm), Satisfaction formula: C × T / 1000000 × Yt < 0.5 × Ya.

The plurality of first main electrodes 52ab are arranged in parallel at a predetermined interval so as to be parallel in the longitudinal direction. The plurality of second main electrodes 53ab are arranged in parallel at a predetermined interval so as to be parallel in the longitudinal direction.

The first connection target member 52Y has the first electrode 52aa for alignment. The second connection target member 53Y has the second electrode 53aa for alignment. The first main electrode 52ab does not include the first electrode 52aa for alignment. The second main electrode 53ab does not include the second electrode 53aa for alignment.

The first main electrode 52ab and the second main electrode 53ab are electrically connected by the solder portion 54YA. The cured portion 54YB is located around the solder portion 54YA.

The linear expansion ratio was measured under the conditions of a temperature range of 5 ° C/min at a temperature increase rate of 5 ° C/min and a heating temperature of the conductive paste when the connection portion was formed. The above linear expansion ratio is obtained as an average value under the above temperature range conditions.

In order to efficiently dispose the solder particles on the electrode, the viscosity of the conductive paste at 25 ° C is preferably 10 Pa ‧ or more, more preferably 50 Pa ‧ s or more, further preferably 100 Pa ‧ or more, and preferably It is 800 Pa‧s or less, more preferably 600 Pa‧s or less, and further preferably 500 Pa‧s or less.

The above viscosity can be appropriately adjusted by the type of the blending component and the blending amount. Also, by using a filler, the viscosity can be made relatively high.

The viscosity can be measured, for example, at 25 ° C and 5 rpm using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.).

The lowest value (the value of the lowest melt viscosity) of the conductive paste under the temperature range of 25 ° C or more and the melting point of the solder particles (solder) below C ° C is preferably 0.1 Pa ‧ More preferably, it is 0.2 Pa‧s or more, and is preferably 10 Pa‧s or less, more preferably 1 Pa‧s or less. When the lowest value of the viscosity is equal to or higher than the lower limit and equal to or lower than the upper limit, the solder particles can be more efficiently disposed on the electrode.

The minimum value of the viscosity can be STRESSTECH (manufactured by EOLOGICA Co., Ltd.), strain control 1 rad, frequency 1 Hz, temperature increase rate 20 ° C / min, measurement temperature range 40 to 200 ° C (wherein the melting point of the solder particles exceeds 200 ° C) The measurement was carried out under the conditions that the upper limit of the temperature was set to the melting point of the solder particles. Based on the measurement results, the lowest value of the viscosity under the temperature range of the melting point of the solder particles below °C was evaluated.

The conductive paste contains a thermosetting component and solder particles. The thermosetting component preferably contains a curable compound (thermosetting compound) which can be cured by heating, and a thermosetting agent. The above conductive paste preferably contains a flux. The above conductive paste preferably contains a filler.

Hereinafter, other details of the present invention will be described.

(solder particles)

The solder particles have solder on the outer surface of the conductive layer. Regarding the above solder particles, the central portion and the conductive outer surface are formed of solder.

The above solder is preferably a low melting point metal having a melting point of 450 ° C or less. The solder particles are preferably low melting point metal particles having a melting point of 450 ° C or lower. The low melting point metal particles are particles containing a low melting point metal. The so-called low melting point metal means a metal having a melting point of 450 ° C or lower. The melting point of the low melting point metal is preferably 300 ° C or lower, more preferably 160 ° C or lower. Further, the solder particles contain tin. The content of tin in the 100% by weight of the metal contained in the solder particles is preferably 30% by weight or more, more preferably 40% by weight or more, still more preferably 70% by weight or more, and particularly preferably 90% by weight or more. When the content of tin in the solder particles is at least the above lower limit, the connection reliability between the solder portion and the electrode is further improved.

Further, the content of the tin may be a high-frequency inductively coupled plasma emission spectrometer ("ICP-AES" manufactured by Horiba, Ltd.) or a fluorescent X-ray analyzer (island). The measurement was carried out by "EDX-800HS" manufactured by Tsusho Corporation.

By using the above-described solder particles, the solder is melted and bonded to the electrodes, and the solder portion electrically conducts between the electrodes. For example, since the solder portion and the electrode are easily in surface contact instead of point contact, the connection resistance becomes low. Moreover, by using the solder particles, the bonding strength between the solder portion and the electrode is increased, and as a result, peeling of the solder portion and the electrode is less likely to occur, and the conduction reliability and the connection reliability are effectively improved.

The low melting point metal constituting the solder particles is not particularly limited. The low melting point metal is preferably tin or an alloy containing tin. Examples of the alloy include a tin-silver alloy, a tin-copper alloy, a tin-silver-copper alloy, a tin-bismuth alloy, a tin-zinc alloy, and a tin-indium alloy. Among them, the low melting point metal is preferably tin, tin-silver alloy, tin-silver-copper alloy, tin-bismuth alloy, or tin-indium alloy in terms of excellent wettability of the electrode. More preferably, it is a tin-bismuth alloy or a tin-indium alloy.

The solder particles are preferably a filler material having a liquidus of 450 ° C or less, based on JIS Z3001: welding term. Examples of the composition of the solder particles include a metal composition containing zinc, gold, silver, lead, copper, tin, antimony, indium, or the like. Among them, a tin-indium-based (117 ° C eutectic) or a tin-lanthanide (139 ° C eutectic) having a low melting point and no lead is preferable. That is, the solder particles preferably do not contain lead, and preferably contain tin and indium or tin and antimony.

In order to further improve the bonding strength between the solder portion and the electrode, the solder particles may further contain phosphorus, antimony, or nickel, copper, bismuth, aluminum, zinc, iron, gold, titanium, lanthanum, cobalt, lanthanum, manganese, chromium, molybdenum. , palladium and other metals. Further, from the viewpoint of further improving the bonding strength between the solder portion and the electrode, the solder particles preferably contain nickel, copper, ruthenium, aluminum or zinc. The content of the metal for improving the bonding strength is preferably 0.0001% by weight or more, and preferably 1% by weight, based on 100% by weight of the solder particles, from the viewpoint of further improving the bonding strength between the solder portion and the electrode. the following.

The average particle diameter of the solder particles is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 3 μm or more, particularly preferably 5 μm or more, and more preferably 100 μm or less. It is preferably 40 μm or less, more preferably 30 μm or less, still more preferably 20 μm or less, still more preferably 15 μm or less, and most preferably 10 μm or less. When the average particle diameter of the solder particles is not less than the above lower limit and not more than the above upper limit, the solder particles can be more efficiently disposed on the electrode. The average particle diameter of the solder particles is preferably 3 μm or more and 30 μm or less.

The "average particle diameter" of the above solder particles means a number average particle diameter. The average particle diameter of the solder particles can be determined, for example, by observing an arbitrary 50 solder particles by an electron microscope or an optical microscope and calculating an average value.

The content of the solder particles in 100% by weight of the conductive paste is preferably 1% by weight or more, more preferably 2% by weight or more, still more preferably 10% by weight or more, still more preferably 20% by weight or more, and most preferably 30% by weight. The weight% or more is preferably 80% by weight or less, more preferably 60% by weight or less, still more preferably 50% by weight or less. When the content of the solder particles is not less than the above lower limit and not more than the above upper limit, the solder particles can be more efficiently disposed on the electrode, and a large amount of solder particles can be easily disposed between the electrodes, and the conduction reliability can be further improved. From the viewpoint of further improving the conduction reliability, the content of the above solder particles is preferably large.

(a compound that can be hardened by heating: a thermosetting component)

Examples of the thermosetting compound include an oxetane compound, an epoxy compound, an episulfide compound, a (meth)acrylic compound, a phenol compound, an amine compound, an unsaturated polyester compound, and a polyaminocarboxylic acid. An ester compound, a polyoxymethylene compound, a polyimine compound, or the like. Among them, an epoxy compound is preferred from the viewpoint of further improving the curing property and viscosity of the conductive paste and further improving the connection reliability.

The content of the thermosetting compound in the 100% by weight of the conductive paste is preferably 20% by weight or more, more preferably 40% by weight or more, further preferably 50% by weight or more, and preferably 99% by weight or less. It is preferably 98% by weight or less, more preferably 90% by weight or less, and still more preferably 80% by weight or less. From the viewpoint of further improving the impact resistance, the content of the thermosetting component is preferably large.

(thermosetting agent: thermosetting component)

The above-mentioned thermosetting agent thermally hardens the above-mentioned thermosetting compound. Examples of the above-mentioned thermosetting agent include an imidazole curing agent, an amine curing agent, a phenol curing agent, a polythiol curing agent, an acid anhydride, a thermal cation initiator, and a thermal radical generating agent. These thermosetting agents may be used alone or in combination of two or more.

Among them, an imidazole hardener, a polythiol hardener or an amine hardener is preferred because the conductive paste can be hardened more rapidly at a low temperature. Further, since the storage stability is improved when the curable compound which can be cured by heating is mixed with the above-mentioned thermosetting agent, a latent curing agent is preferable. The latent hardener is preferably a latent imidazole hardener, a latent polythiol hardener or a latent amine hardener. Further, the above-mentioned thermosetting agent may be coated with a polymer material such as a polyurethane resin or a polyester resin.

The imidazole curing agent is not particularly limited, and examples thereof include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, and trimellitic acid 1-cyanide. Ethyl-2-phenylimidazolium salt, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-all three And 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-all three An isocyanuric acid addition product or the like.

The polythiol curing agent is not particularly limited, and examples thereof include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), and dipentaerythritol hexa(3-mercaptopropane). Acid ester) and the like.

The solubility parameter of the above-mentioned polythiol hardener is preferably 9.5 or more, and preferably 12 or less. The above solubility parameters are calculated by the Fedors method. For example, the solubility parameter of trimethylolpropane tris(3-mercaptopropionate) is 9.6, and the solubility parameter of dipentaerythritol hexa(3-mercaptopropionate) is 11.4.

The amine curing agent is not particularly limited, and examples thereof include hexamethylenediamine, octanediamine, decanediamine, and 3,9-bis(3-aminopropyl)-2,4,8,10-tetraro [5.5] Undecane, bis(4-aminocyclohexyl)methane, m-phenylenediamine, and diaminodiphenylphosphonium.

Examples of the thermal cation hardening agent include a lanthanoid cation curing agent, an oxonium cation curing agent, and a lanthanoid cation curing agent. As the above-mentioned lanthanide cationic hardener, A bis(4-t-butylphenyl) ruthenium hexafluorophosphate etc. are mentioned. Examples of the oxonium-based cationic curing agent include trimethyloxonium tetrafluoroborate. Examples of the ruthenium-based cation hardener include tris(p-tolyl)phosphonium hexafluorophosphate.

The thermal radical generating agent is not particularly limited, and examples thereof include an azo compound and an organic peroxide. Examples of the azo compound include azobisisobutyronitrile (AIBN) and the like. Examples of the organic peroxide include ditributyl peroxide and methyl ethyl ketone peroxide.

The reaction initiation temperature of the above-mentioned thermosetting agent is preferably 50 ° C or more, more preferably 70 ° C or more, further preferably 80 ° C or more, and preferably 250 ° C or less, more preferably 200 ° C or less, and further preferably Below 150 ° C, particularly preferably below 140 ° C. When the reaction initiation temperature of the thermal curing agent is not less than the above lower limit and not more than the above upper limit, the solder particles can be more efficiently disposed on the electrode. The reaction initiation temperature of the above-mentioned thermosetting agent is particularly preferably 80 ° C or more and 140 ° C or less.

From the viewpoint of more efficiently disposing the solder on the electrode, it is preferred that the reaction initiation temperature of the above-mentioned thermosetting agent is lower than the melting point of the solder in the solder particles, more preferably 5 ° C or more, and further preferably It is 10 ° C or lower.

The reaction initiation temperature of the above-mentioned thermosetting agent means a temperature at which an exothermic peak in DSC (differential scanning calorimetry) starts to rise.

The content of the above-mentioned thermosetting agent is not particularly limited. The content of the above-mentioned thermosetting agent is preferably 0.01 parts by weight or more, more preferably 1 part by weight or more, and preferably 200 parts by weight or less, more preferably 100 parts by weight or less, based on 100 parts by weight of the thermosetting compound. Further, it is preferably 75 parts by weight or less. When the content of the thermosetting agent is at least the above lower limit, the conductive paste is easily sufficiently cured. When the content of the thermosetting agent is at most the above upper limit, it is less likely to remain unnecessary after curing, and the heat resistance of the cured product is further improved.

(flux)

The above conductive paste preferably contains a flux. By using a flux, the solder can be more efficiently disposed on the electrode. The flux is not particularly limited. As the flux, a flux which is usually used for soldering or the like can be used. Examples of the flux include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, a phosphoric acid, a derivative of phosphoric acid, an organic halide, an anthracene, and an organic acid. And turpentine and so on. The flux may be used singly or in combination of two or more.

Examples of the molten salt include ammonium chloride and the like. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamic acid, and glutaric acid. Examples of the rosin include activated rosin and non-activated rosin. The flux is preferably an organic acid or rosin having two or more carboxyl groups. The flux may be an organic acid having two or more carboxyl groups or a rosin. By using an organic acid or rosin having two or more carboxyl groups, the conduction reliability between the electrodes is further improved.

The above rosin is a rosin mainly composed of rosin acid. The flux is preferably rosin, more preferably rosin acid. By using the preferred flux, the conduction reliability between the electrodes is further improved.

The melting point of the flux is preferably 50 ° C or higher, more preferably 70 ° C or higher, further preferably 80 ° C or higher, and more preferably 200 ° C or lower, more preferably 160 ° C or lower, and still more preferably 150 ° C or lower. More preferably, it is 140 ° C or less. When the melting point of the flux is not less than the above lower limit and not more than the above upper limit, the flux effect is more effectively exhibited, and the solder particles can be more efficiently disposed on the electrode. The melting point of the above flux is preferably 80 ° C or more and 190 ° C or less. The melting point of the above flux is particularly preferably 80 ° C or more and 140 ° C or less.

Examples of the flux having a melting point of 80 ° C or more and 190 ° C or less include succinic acid (melting point 186 ° C), glutaric acid (melting point 96 ° C), adipic acid (melting point 152 ° C), and pimelic acid (melting point 104). °C), dicarboxylic acid such as suberic acid (melting point 142 ° C); benzoic acid (melting point 122 ° C), malic acid (melting point 130 ° C) and the like.

Further, the flux has a boiling point of preferably 200 ° C or lower.

From the viewpoint of more efficiently disposing the solder on the electrode, it is preferable that the melting point of the flux is lower than the melting point of the solder in the solder particles, more preferably 5 ° C or more, and further preferably 10 ° C lower. the above.

From the viewpoint of more efficiently disposing the solder on the electrode, it is preferred that the melting point of the flux is lower than the reaction starting temperature of the thermal curing agent, more preferably 5 ° C or more, and even more preferably 10 lower. Above °C.

The flux may be dispersed in the conductive paste or attached to the surface of the solder particles.

The content of the flux in 100% by weight of the conductive paste is preferably 0.5% by weight or more, and preferably 30% by weight or less, more preferably 25% by weight or less. The above conductive paste may also contain no flux. When the content of the flux is not less than the above lower limit and not more than the above upper limit, it becomes more difficult to form an oxide film on the surface of the solder and the electrode, and the oxide film formed on the surface of the solder and the electrode can be more effectively removed.

(filler)

The above conductive paste preferably contains a filler. By using a filler, the latent heat expansion of the cured product of the conductive paste can be suppressed. These fillers may be used alone or in combination of two or more.

Examples of the filler include inorganic fillers such as cerium oxide, talc, aluminum nitride, and aluminum oxide. The above filler may be an organic filler or an organic-inorganic composite filler. These fillers may be used alone or in combination of two or more.

Preferably, the conductive paste and the filler each contain an inorganic filler. By using an inorganic filler, the specific gravity and thixotropy of the conductive paste can be controlled to a better range, the precipitation of the solder particles is further suppressed, and the conduction reliability of the bonded structure is further improved.

Preferably, the conductive paste and the filler each contain cerium oxide. The cerium oxide is a cerium oxide filler. By using cerium oxide, the specific gravity and thixotropy of the conductive paste can be controlled to a better range, the precipitation of the solder particles is further suppressed, and the conduction reliability of the bonded structure is further improved.

The content of the filler in 100% by weight of the conductive paste is preferably 2% by weight or more, more preferably 5% by weight or more, and is preferably 60% by weight or less, more preferably 50% by weight or less. When the content of the filler is not less than the above lower limit and not more than the above upper limit, the solder particles can be more efficiently disposed on the electrode.

(other ingredients)

The conductive paste may also contain, for example, a filler, a bulking agent, a softener, a plasticizer, a polymerization catalyst, a hardening catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, a UV absorber, and a lubricant. Various additives such as antistatic agents and flame retardants.

Hereinafter, the present invention will be specifically described by way of examples and comparative examples. The invention is not limited to the following examples.

Polymer A: Synthesis of a reaction of bisphenol F with 1,6-hexanediol diglycidyl ether and bisphenol F-type epoxy resin (Polymer A): bisphenol F (by weight ratio 2 :3:1 contains 4,4'-methylene bisphenol, 2,4'-methylene bisphenol and 2,2'-methylene bisphenol) 72 parts by weight, 1,6-hexanediol II 30 parts by weight of glycidyl ether and 30 parts by weight of bisphenol F-type epoxy resin ("EPICLON EXA-830CRP" manufactured by DIC Corporation) were placed in a three-necked flask, and dissolved at 150 ° C under a nitrogen gas flow. Thereafter, 0.1 part by weight of tetra-n-butyl bromide as an addition reaction catalyst of a hydroxyl group and an epoxy group was added, and an addition polymerization reaction was carried out at 150 ° C for 6 hours under a nitrogen gas flow to obtain a reaction. (Polymer A).

It was confirmed by NMR (nuclear magnetic resonance) that the addition polymerization reaction was carried out, and it was confirmed that the reactant (polymer A) had a hydroxyl group derived from bisphenol F and 1,6-hexane in the main chain. A structural unit in which an epoxy group of an alcohol diglycidyl ether and a bisphenol F type epoxy resin are bonded and has an epoxy group at both ends.

The weight average molecular weight of the reactant (polymer A) obtained by GPC (gel permeation chromatography) is 10,000, and the number average molecular weight is 3500.

Polymer B: two-terminal epoxy-based rigid skeleton phenoxy resin, "YX6900BH45" manufactured by Mitsubishi Chemical Corporation, weight average molecular weight 16000

Thermosetting compound 1: Resorcinol type epoxy compound, "EX-201" manufactured by Nagase ChemteX

Thermosetting compound 2: naphthalene type epoxy compound, "HP-4032D" manufactured by DIC Corporation

Thermosetting compound 3: bisphenol F type epoxy resin, "EVA-830CRP" manufactured by DIC Corporation

Thermal hardener: pentaerythritol tetrakis(3-mercaptobutyrate), "Karenz MT PE1" manufactured by Showa Denko

Flux: glutaric acid, manufactured by Wako Pure Chemical Industries Co., Ltd.

Latent epoxy heat hardener: "Fujicure 7000" manufactured by T&K TOKA

Latent heat hardener: Microcapsule type, "HXA-3932HP" manufactured by Asahi Kasei E-MATERIALS

Solder particles 1 (Sn-58Bi solder particles, melting point 139 ° C, "DS10-25" manufactured by Mitsui Mining Co., Ltd., average particle size 10 μm)

Solder particles 2 (Sn-58Bi solder particles, melting point 139 ° C, "10-25" manufactured by Mitsui Mining & Mining Co., Ltd., average particle size 20 μm)

Solder particles 3 (Sn-58Bi solder particles, melting point 139 ° C, "DS20-38" manufactured by Mitsui Mining Co., Ltd., average particle size 29 μm)

Solder particles 4 (Sn-58Bi solder particles, melting point 139 ° C, average particle size 45 μm, screening product)

Conductive particle 1 : A copper layer having a thickness of 1 μm was formed on the surface of the resin particle, and a conductive layer having a thickness of 3 μm (tin: 铋 = 43% by weight: 57% by weight) was formed on the surface of the copper layer.

In the method of producing the conductive particles 1, electroless nickel plating is performed on divinylbenzene resin particles ("Micropearl SP-210" manufactured by Sekisui Chemical Co., Ltd.) having an average particle diameter of 10 μm, and a thickness of 0.1 is formed on the surface of the resin particles. The base of μm is plated with nickel. Then, the resin particles on which the underlying nickel plating layer was formed were subjected to electrolytic copper plating to form a copper layer having a thickness of 1 μm. Further, electroplating using a plating solution containing tin and antimony was carried out to form a solder layer having a thickness of 3 μm. In the above manner, a copper layer having a thickness of 1 μm was formed on the surface of the resin particle, and a conductive layer having a thickness of 3 μm (tin: 铋 = 43% by weight: 57% by weight) was formed on the surface of the copper layer. 1.

Phenoxy resin ("YP-50S" manufactured by Nippon Steel & Sumitomo Chemical Co., Ltd.)

(Examples 1 to 4)

(1) Production of anisotropic conductive paste

The components shown in the following Table 1 were blended in the amounts shown in Table 1 below to obtain an anisotropic conductive paste.

(2) Production of the first connection structure (L/S = 50 μm / 50 μm)

Prepare a copper electrode pattern with an L/S of 50 μm/50 μm on the upper surface (copper electrode thickness 10) The epoxy glass substrate (FR-4 substrate) of the μm) (the first connection member, the coefficient of linear expansion is 12 ppm/° C. (the linear expansion ratio in the longitudinal direction and the width direction of the first main electrode (the same applies hereinafter)). In addition, a flexible printed circuit board having a copper electrode pattern (copper electrode thickness: 10 μm) on the surface of L/S of 50 μm/50 μm is prepared (the second connection member has a linear expansion ratio of 16 ppm/° C. (longitudinal direction and width of the second main electrode) The linear expansion ratio in the direction (the same below))). Regarding the first main electrode, Yt = 10 mm and Ya = 0.05 mm.

The overlapping area of the epoxy glass substrate and the flexible printed circuit board was set to 1.5 cm × 4 mm, and the number of connected electrodes was set to 100 pairs. The electrode for alignment (four in total) is placed on the inside of the four corners of the connection portion of the obtained first connection structure, and the flexible printed circuit board. The shortest distance between the first and second electrodes for alignment and the front ends of the four corners was 500 μm.

The anisotropic conductive paste immediately after the production was applied to the upper surface of the above-mentioned epoxy glass substrate so as to have a thickness of 50 μm to form an anisotropic conductive paste layer. Next, the flexible printed circuit board is laminated on the upper surface of the anisotropic conductive paste layer so that the electrodes face each other. At this time, no pressurization is performed. The weight of the above flexible printed substrate is applied to the anisotropic conductive paste layer. Then, while the temperature of the anisotropic conductive paste layer was 185 ° C, the solder was melted, and the anisotropic conductive paste layer was cured at 185 ° C to obtain a first bonded structure.

(3) Production of the second connection structure (L/S = 75 μm / 75 μm)

An epoxy glass substrate (FR-4 substrate) having a copper electrode pattern (copper electrode thickness: 10 μm) having an L/S of 75 μm/75 μm (the first connection member, a linear expansion ratio of 12 ppm/° C.) was prepared. Further, a flexible printed circuit board having a copper electrode pattern (copper electrode thickness: 10 μm) having an L/S of 75 μm/75 μm (a second connection member, a linear expansion ratio of 16 ppm/° C.) was prepared. Regarding the first main electrode, Yt = 10 mm and Ya = 0.075 mm.

The overlapping area of the epoxy glass substrate and the flexible printed circuit board was set to 1.5 cm × 4 mm, and the number of connected electrodes was set to 67 pairs. In addition to using L/S different epoxy glass substrates and soft The second connection structure is obtained in the same manner as the production of the first connection structure except for the printed circuit board.

(4) Production of the third connection structure (L/S = 100 μm / 100 μm)

An epoxy glass substrate (FR-4 substrate) having a copper electrode pattern (copper electrode thickness: 10 μm) having an L/S of 100 μm/100 μm on the upper surface (first connection member, linear expansion ratio: 12 ppm/° C.) was prepared. Further, a flexible printed circuit board having a copper electrode pattern (copper electrode thickness: 10 μm) having an L/S of 100 μm/100 μm on the lower surface (second connection member, linear expansion ratio: 16 ppm/° C.) was prepared. Regarding the first main electrode, Yt = 10 mm and Ya = 0.1 mm.

The overlapping area of the epoxy glass substrate and the flexible printed circuit board was set to 1.5 cm × 4 mm, and the number of connected electrodes was set to 50 pairs.

The third connection structure was obtained in the same manner as the production of the first connection structure except that the above-described epoxy glass substrate and flexible printed circuit board having different L/S were used.

(Example 5)

The number of electrodes of the first connection structure is 75 pairs, the number of electrodes of the second connection structure is 50 pairs, and the number of electrodes of the third connection structure is 38 pairs, and other examples are given. 1 The connection structure is obtained in the same manner.

Yt and Ya of the first main electrode are as follows.

First, second, and third connection structures: Yt = 7.5 mm

First connection structure: Ya=0.05mm

Second connection structure: Ya=0.075mm

Third connection structure: Ya=0.1mm

(Example 6)

The first, second, and third connection structures were produced in the same manner as in the first embodiment except that the epoxy glass substrate not having the alignment electrode and the flexible printed circuit board having no alignment electrode were used.

(Example 7)

A semiconductor wafer (thickness: 400 μm) having a cell size/electrode pitch of 100 μm/100 μm, 75 μm/75 μm, 50 μm/50 μm, and a glass substrate (having a size of 30×30 mm, thickness 0.4 mm) having a 5 mm square semiconductor wafer (thickness: 400 μm) Other than this, the first, second, and third connection structures were obtained in the same manner as in the first embodiment.

(Examples 8 to 11)

The components shown in the following Table 1 were blended in the amounts shown in Table 1 below to obtain an anisotropic conductive paste. The first, second, and third connection structures were obtained in the same manner as in Example 1 except that the obtained anisotropic conductive paste was used.

(Comparative Example 1)

When the flexible printed circuit board was laminated on the upper surface of the anisotropic conductive paste layer so that the electrodes were opposed to each other, a pressure of 2 MPa was applied to the flexible printed circuit board, and the same procedure as in Example 1 was obtained. The first, second, and third connection structures.

(Comparative Example 2)

When the anisotropic conductive paste layer was cured, the first, second, and third connection structures were obtained in the same manner as in Example 1 except that a pressure of 2 MPa was applied to the flexible printed circuit board.

(Comparative Example 3)

When the flexible printed circuit board is laminated on the upper surface of the anisotropic conductive paste layer so that the electrodes face each other, a pressure of 2 MPa is applied to the flexible printed circuit board, and the flexible printed circuit board is placed so that the electrodes face each other. After laminating on the upper surface of the anisotropic conductive paste layer, the pressure is maintained, and when the anisotropic conductive paste layer is cured, a pressure of 2 MPa is applied to the flexible printed circuit board, and otherwise, in the same manner as in the first embodiment, The first, second, and third connection structures were obtained.

(Comparative Example 4)

10 parts by weight of a phenoxy resin ("YP-50S" manufactured by Nippon Steel & Sumitomo Chemical Co., Ltd.) was dissolved in methyl ethyl ketone (MEK) so that the solid content was 50% by weight. A solution is obtained. The components other than the phenoxy resin shown in the following Table 2 were mixed with the total amount of the above-mentioned solution, and the mixture was stirred at 2000 rpm for 5 minutes using a planetary mixer at a blending amount shown in the following Table 2, and then coated with a bar. The cloth machine was applied to a release PET (polyethylene terephthalate) film so that the thickness after drying became 30 μm. The MEK was removed by vacuum drying at room temperature, whereby an anisotropic conductive film was obtained.

The first, second, and third connection structures were obtained in the same manner as in Example 1 except that the anisotropic conductive film was used.

(Comparative Example 5)

A semiconductor wafer (thickness: 400 μm) having a cell size/electrode pitch of 100 μm/100 μm, 75 μm/75 μm, 50 μm/50 μm, and a glass substrate (having a size of 30×30 mm, thickness 0.4 mm) having a 5 mm square semiconductor wafer (thickness: 400 μm) In addition, the first, second, and third connection structures were obtained in the same manner as in Example 7 except that a pressure of 10 MPa was applied when the anisotropic conductive paste layer was cured.

(Comparative Example 6)

The components shown in the following Table 2 were blended in the amounts shown in Table 2 below to obtain an anisotropic conductive paste. The first, second, and third connection structures were obtained in the same manner as in Example 1 except that the obtained anisotropic conductive paste was used.

(assessment)

(1) Viscosity

The viscosity of the anisotropic conductive paste was measured at 25 ° C and 5 rpm using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.).

(2) Minimum melt viscosity

The lowest melt viscosity of the anisotropic conductive paste under the temperature range from 25 ° C to the melting point of the solder particles or the melting point of the solder on the surface of the conductive particles was measured.

(3) Distance of the connecting portion (interval between electrodes)

By observing the cross-section of the obtained first connected structure, the upper and lower electrodes are The distance D1 (the interval between the electrodes) of the connection portion to the position is evaluated.

(4) Status of the electrode

The size of the portion S1 where the first and second electrodes face each other and the size S2 of the portion where the first and second electrodes are not opposed are evaluated in a plan view of the first connection structure obtained in a plan view. Find the ratio (size S1/size S2).

(5) The maximum distance at which the electrodes are displaced from each other

The maximum distance of the positional shift of the upper and lower electrodes was evaluated by performing cross-sectional observation of the obtained first, second, and third connection structures.

(6) Arrangement accuracy of the solder on the electrode

In the cross section of the obtained first, second, and third connection structures (the cross section in the direction shown in FIG. 1), the solder portion disposed between the electrodes is separated from the total area of the solder by 100% and remains hardened. The area (%) of the solder in the material was evaluated. Furthermore, the average of the areas of the five sections is calculated. The arrangement accuracy of the solder on the electrodes was determined in accordance with the following criteria.

[Criteria for determining the placement accuracy of the solder on the electrode]

○○: The area of the solder (solder particles) remaining in the cured product separated from the solder portion disposed between the electrodes by 100% of the total area of the solder which is present in the cross section is 0%

○: 100% of the total area of the solder which is present in the cross section, the area of the solder (solder particles) remaining in the hardened material separated from the solder portion disposed between the electrodes is more than 0% and is 10% or less

Δ: 100% of the total area of the solder which is present in the cross section, the area of the solder (solder particles) remaining in the hardened material separated from the solder portion disposed between the electrodes is more than 10% and is 30% or less

×: The area of the solder (solder particles) remaining in the hardened material separated from the solder portion disposed between the electrodes is more than 30% in the total area of the solder which is present in the cross section.

(7) Continuity reliability between upper and lower electrodes

The first, second, and third connected structures obtained by the four-terminal method were respectively measured (n=15). The connection resistance between the upper and lower electrodes. Calculate the average of the connection resistance. Furthermore, the connection resistance can be obtained by measuring the voltage at which a constant current flows in accordance with the relationship of voltage=current×resistance. The conduction reliability was determined according to the following criteria.

[Determination of Conductivity Reliability]

○○: The average value of the connection resistance is 8.0 Ω or less.

○: The average value of the connection resistance exceeds 8.0 Ω and is 10.0 Ω or less.

△: The average value of the connection resistance exceeds 10.0 Ω and is 15.0 Ω or less.

×: The average value of the connection resistance exceeds 15.0 Ω

(8) Insulation reliability between adjacent electrodes

After placing the first, second, and third connected structures (n=15) obtained in the environment at a temperature of 85 ° C and a humidity of 85% for 100 hours, a voltage of 5 V was applied between the adjacent electrodes. The resistance value was measured at 25 locations. The insulation reliability was determined according to the following criteria.

[Determination of insulation reliability]

○○: The average value of the connection resistance is 10 ⁷ Ω or more.

○: The average value of the connection resistance is 10 ⁶ Ω or more and less than 10 ⁷ Ω

△: The average value of the connection resistance is 10 ⁵ Ω or more and less than 10 ⁶ Ω.

×: The average value of the connection resistance is less than 10 ⁵ Ω

The results are shown in Tables 1 and 2 below.

According to the difference between the results of Examples 1 to 11 and Comparative Examples 1 to 5, it was found that the effect of improving the conduction reliability can be obtained without performing pressurization.

According to the results of Examples 1 to 5, 8 to 11, and Example 6, it is found that if the electrodes for alignment are provided, the positional deviation of the electrodes can be suppressed.

According to the difference between the results of the first embodiment and the comparative example 1 and the difference between the results of the seventh embodiment and the comparative example 5, when the second connection target member is a flexible printed circuit board, the second connection target member is a semiconductor. Compared with the case of the wafer, the effect of improving the conduction reliability can be more effectively obtained without performing pressurization.

The same applies to the case where a resin film, a flexible flat cable, and a rigid flexible substrate are used instead of the flexible printed substrate.

Further, in the connection structure obtained in the first to eleventh embodiments, when the first electrode and the second electrode face each other in the direction of lamination of the first electrode, the connection portion, and the second electrode, the first The solder portion in the connection portion is disposed at 50% or more of the area of the portion where the electrode and the second electrode face each other.

Further, Fig. 7 (a), (b) and (c) show an example of a connection structure included in the embodiment of the present invention. 7(a) and 7(b) are cross-sectional images, and Fig. 7(c) is a planar image. In (a), (b), and (c) of FIG. 7, it is understood that there is no solder (solder particles) remaining in the cured product due to the separation of the solder portions disposed between the electrodes.

Further, Fig. 8 (a), (b) and (c) show an example of a connection structure which is not included in the embodiment of the present invention. The connection structure is a connection structure obtained by pressurizing in the step of arranging the second connection member. 8(a) and 8(b) are cross-sectional images, and Fig. 8(c) is a planar image. In (a), (b), and (c) of FIG. 8 , it is found that a plurality of solder (solder particles) remaining in the cured portion separated from the solder portion disposed between the electrodes are present on the side surface of the solder portion. Further, it was confirmed that the connection structure obtained in the step of forming the connection portion can be obtained in the same manner as the connection structure shown in Figs. 8(a), (b) and (c).

1‧‧‧Connection structure

2‧‧‧1st connection object component

2a‧‧‧1st electrode

3‧‧‧2nd connection object component

3a‧‧‧2nd electrode

4‧‧‧Connecting Department

4A‧‧‧ solder department

4B‧‧‧ Hardened Parts

Claims (8)

A method for producing a connection structure comprising the steps of disposing the conductive paste on a surface of a first connection member having at least one first electrode on its surface using a conductive paste containing a plurality of solder particles and a thermosetting component And the second connection member having at least one second electrode on the surface thereof is disposed on the surface of the conductive paste opposite to the first connection member side so that the first electrode and the second electrode face each other And heating the connection portion of the first connection member and the second connection member by the conductive paste by heating the conductive paste to a temperature equal to or higher than a melting point of the solder particles and a curing temperature of the thermosetting component. In the step of arranging the second connection member and the step of forming the connection portion, the weight of the second connection member is applied to the conductive paste without applying pressure. The method of manufacturing a connection structure according to claim 1, wherein the second connection target member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate. The method of manufacturing the connection structure according to claim 1 or 2, wherein a distance between the connection portion at a position where the first electrode and the second electrode face each other is 3 μm or more and 40 μm or less. The method of manufacturing the connection structure according to claim 1 or 2, wherein a size of a portion of the connecting portion facing the first electrode and the second electrode is such that the first electrode and the second electrode are not It is 2 times or more and 40 times or less the size of the part. The method for producing a joined structure according to claim 1 or 2, wherein the viscosity at 25 ° C is 10 Pa ‧ or more and 800 Pa ‧ or less. The method for producing a bonded structure according to claim 1 or 2, wherein the minimum value of the viscosity under the temperature range of the melting point or lower of the solder particles is 0.1 Pa ‧ or more and 10 Pa ‧ or less. The method of manufacturing the connection structure according to claim 1 or 2, wherein the connection portion has a corner portion, and the first connection target member has a first electrode for alignment on the inner side of the corner portion as the first electrode, wherein the first electrode (2) The connection target member has a second electrode for alignment on the inner side of the corner portion as the second electrode, and the shortest distance between the first electrode for alignment and the second electrode for alignment and the front end of the corner portion It is 75 μm or more and 3000 μm or less. The method of manufacturing the connection structure according to claim 1 or 2, wherein the first connection target member has a plurality of first main electrodes having a longitudinal direction and a width direction as the first electrode, and the second connection target member has a plurality of a second main electrode having a longitudinal direction and a width direction as the second electrode, and a linear expansion ratio of the first connection member and a length of the second main electrode in a longitudinal direction and a width direction of the first main electrode The difference in linear expansion ratio of the second connection member in the direction and the width direction is C (ppm/° C.), and the heating temperature of the conductive paste when the connection portion is formed is T (° C.) When the size of the plurality of first main electrodes in the width direction of the main electrode is Yt (mm), and the size of each of the plurality of first main electrodes in the width direction is Ya (mm), Satisfaction formula: C × T / 1000000 × Yt < 0.5 × Ya.