Method for manufacturing circuit connection structure and circuit connection device

Abstract

This method for manufacturing a circuit connection structure (40) is provided with: a step (a) in which a circuit connection material provided with a solder connection material (1) and an adhesive is disposed on a surface of a first circuit member (10) having a first electrode (12) on which the first electrode (12) is formed; a step (b) in which a second circuit member (20) having a second electrode (22) is disposed on the first circuit member (10) such that the first electrode (12) and the second electrode (22) face each other; (c) thermocompression bonding the first circuit member (10) and the second circuit member (20) at a temperature equal to or higher than the melting point of the solder connection material (1) in a state where the solder connection material (1) is interposed between the first electrode (12) and the second electrode (22); and a step (d) in which the temperature between the first electrode (12) and the second electrode (22) is cooled while pressurizing between the first electrode (12) and the second electrode (22) until the temperature between the first electrode (12) and the second electrode (22) is equal to or greater than the melting point of the solder connection material (1) from a temperature equal to or greater than the melting point of the solder connection material (1) to a temperature equal to or less than the melting point of the solder connection material (1).

Description

Technical Field

[0001] The invention relates to a method for manufacturing a circuit connection structure and a circuit connection device. Background Art

[0002] In the fields of semiconductors, liquid crystal displays, etc., solder is used as a connecting material between electrodes of circuit components such as semiconductor chips and circuit substrates. For example, Patent Document 1 discloses a method for forming solder bumps used to connect a semiconductor device to a substrate by flip chip mounting or the like.

[0003] Previous technical literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-157626 Summary of the invention

[0006] Technical issues to be solved by the invention

[0007] Circuit connection using solder is performed by heating the solder to a high temperature to melt and form a eutectic by using a reflow furnace, etc. However, with the recent increase in global awareness of recycling-oriented societies such as carbon neutrality, green guidance, and SDGS, and the promotion of environmental-related investments, the demand for lower-energy circuit connection methods is increasing.

[0008] As one of the methods for implementing circuit connection using solder at a lower energy, there is a method of manufacturing a circuit connection structure by heating and pressing circuit components disposed opposite to each other via solder (i.e., thermocompression bonding). According to this method, circuit components can be connected at a lower temperature.

[0009] However, in the above method, minute cracks are likely to occur in the inter-electrode connection portion (solder connection portion) of the circuit connection structure, and such cracks may cause problems such as a decrease in connection reliability.

[0010] Therefore, an object of one aspect of the present invention is to reduce cracks in the inter-electrode connection portion that occur when solder is used as a connection material between opposing electrodes in a method of manufacturing a circuit connection structure by thermocompression bonding circuit components.

[0011] Means for solving technical problems

[0012] Some aspects of the present invention provide the following [1] to [6]. [1]

[0014] A method for manufacturing a circuit connection structure, comprising:

[0015] Step (a), disposing a circuit connection material including a solder connection material and an adhesive on a surface of a first circuit component having a first electrode on which the first electrode is formed;

[0016] Step (b), disposing a second circuit component having a second electrode on the first circuit component in such a manner that the first electrode and the second electrode face each other;

[0017] Step (c), in a state where a solder connection material is interposed between the first electrode and the second electrode, thermally pressing the first circuit component and the second circuit component at a temperature higher than the melting point of the solder connection material; and

[0018] In step (d), the temperature between the first electrode and the second electrode is lowered from a temperature higher than the melting point of the solder connection material to a temperature lower than the melting point of the solder connection material, and the temperature is cooled while applying pressure between the first electrode and the second electrode. [2]

[0020] The manufacturing method according to [1], wherein

[0021] The solder connection material is solder particles. [3]

[0023] The manufacturing method according to [2], wherein:

[0024] In the step (a), the circuit connecting material is disposed on the first circuit member in the form of a film including the solder particles and the binder. [4]

[0026] The manufacturing method according to [2], wherein:

[0027] In the step (a), the circuit connecting material is disposed on the first circuit member in a paste state including the solder particles and the binder. [5]

[0029] The production method according to any one of [1] to [4], wherein

[0030] The melting point of the solder connection material is below 300°C,

[0031] The thermocompression bonding temperature in the step (c) is 330° C. or lower. [6]

[0033] A circuit connection device used in the manufacturing method described in any one of [1] to [5], the circuit connection device comprising:

[0034] a carrier, mounting the first circuit component or the second circuit component;

[0035] Pressurizing means, pressurizing the first circuit component and the second circuit component in opposite directions;

[0036] Heating means for heating at least one of the first circuit component and the second circuit component; and

[0037] A cooling means for cooling between the first electrode and the second electrode in the step (d).

[0038] Effects of the Invention

[0039] According to one aspect of the present invention, in a method of manufacturing a circuit connection structure by thermocompression bonding circuit components, cracks in the inter-electrode connection portion that occur when solder is used as a connection material between opposing electrodes can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a cross-sectional view schematically showing the step (a) to the step (c) of the method for producing a circuit connection structure according to one embodiment.

[0041] Figure 2 This is a cross-sectional view schematically showing the step (d) of the method for producing a circuit-connected structure according to one embodiment.

[0042] Figure 3 It is a cross-sectional view schematically showing a method for manufacturing a circuit-connected structure according to another embodiment.

[0043] Figure 4 This is a diagram showing the temperature-pressure distribution of Example 1.

[0044] Figure 5 This is a diagram showing the temperature-pressure distribution of Comparative Example 1.

[0045] Figure 6 This is a diagram showing the temperature-pressure distribution of Comparative Example 2. DETAILED DESCRIPTION

[0046] In this specification, the numerical range represented by "~" indicates a range including the numerical values ​​recorded before and after "~" as the minimum value and the maximum value, respectively. In addition, except for the specific explicit cases, the units of the numerical values ​​recorded before and after "~" are the same. In the numerical ranges recorded in stages in this specification, the upper limit or lower limit of the numerical range of a certain stage can be replaced by the upper limit or lower limit of the numerical range of other stages. In addition, in the numerical ranges recorded in this specification, the upper limit or lower limit of the numerical range can also be replaced by the values ​​shown in the embodiments.

[0047] Below, depending on the situation, refer to the attached Figure 1 The embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

[0048] A method for manufacturing a circuit connection structure according to one embodiment comprises: step (a) of disposing a circuit connection material having a solder connection material and an adhesive on a surface of a first circuit component having a first electrode on which the first electrode is formed; step (b) of disposing a second circuit component having a second electrode on the first circuit component in a manner that the first electrode and the second electrode are opposed to each other; step (c) of thermocompression bonding the first circuit component and the second circuit component at a temperature (thermocompression bonding temperature) above the melting point of the solder connection material while the solder connection material is interposed between the first electrode and the second electrode; and step (d) of cooling the space between the first electrode and the second electrode while applying pressure to the space between the first electrode and the second electrode until the temperature between the first electrode and the second electrode is lowered from a temperature above the melting point of the solder connection material to a temperature below the melting point of the solder connection material. In the method for manufacturing a circuit connection structure, after step (d), a step (e) of cooling the space between the first electrode and the second electrode without applying pressure may be further provided.

[0049] In the above-mentioned manufacturing method, a circuit connection structure can be obtained in which cracks between electrodes, that is, cracks in the solder connection portion formed by cooling and solidifying the molten solder connection material, are reduced. The reason for this is presumably as follows.

[0050] First, in a conventional method using a solder connection material, a heating and pressing tool is pressed against a circuit component, and after the circuit component is heated and pressed to be thermocompressed, the heating and pressing tool is separated from the circuit component, thereby substantially simultaneously ending the pressing and heating between the electrodes. In this method, it is presumed that the pressure applied between the electrodes before the molten solder connection material is cooled and solidified by thermocompression bonding is released, so that when the pressure is released, stress in the opposite direction to the opposing direction is applied to the molten solder connection material, causing cracks. On the other hand, according to the above-mentioned manufacturing method, it is presumed that the pressure applied between the electrodes after the molten solder connection material is cooled and solidified by thermocompression bonding is released, thereby reducing the occurrence of the above-mentioned cracks.

[0051] Furthermore, according to the above manufacturing method, solder connection can also be performed at a relatively low temperature (for example, at a temperature below 330°C, below 300°C, below 240°C, below 200°C, below 160°C, below 100°C, etc.). Therefore, for example, a solder connection material having a low melting point of below 300°C, below 280°C, below 220°C, below 180°C, below 140°C, below 80°C, etc. can also be used. Furthermore, according to the above manufacturing method, solder connection can also be performed in a relatively short time (for example, within a short time of 3 minutes, below 1 minute, below 30 seconds, below 15 seconds, below 10 seconds, etc.). That is, according to the above manufacturing method, circuit connection can be performed at a lower energy.

[0052] As the solder connection material used in the above-mentioned production method, a wide range of known materials used as solder can be used. The solder connection material may include, for example, at least one selected from the group consisting of tin, tin alloys, indium, and indium alloys.

[0053] As the tin alloy, for example, In-Sn alloy, In-Sn-Ag alloy, Sn-Au alloy, Sn-Bi alloy, Sn-Bi-Ag alloy, Sn-Ag-Cu alloy, Sn-Cu alloy, etc. Specific examples of these tin alloys include the following.

[0054] ·In-Sn (In 52 mass%, Bi 48 mass%, melting point 118°C)

[0055] · In-Sn-Ag (In 20 mass%, Sn 77.2 mass%, Ag 2.8 mass%, melting point 175°C)

[0056] Sn-Bi (Sn 43 mass%, Bi 57 mass%, melting point 138°C)

[0057] Sn-Bi-Ag (Sn 42 mass%, Bi 57 mass%, Ag 1 mass%, melting point 139°C)

[0058] Sn-Ag-Cu (Sn 96.5 mass%, Ag 3 mass%, Cu 0.5 mass%, melting point 217°C)

[0059] Sn-Cu (Sn 99.3 mass%, Cu 0.7 mass%, melting point 227°C)

[0060] Sn-Au (Sn 21.0 mass%, Au 79.0 mass%, melting point 278°C)

[0061] As the indium alloy, for example, an In-Bi alloy, an In-Ag alloy, etc. can be used. Specific examples of these indium alloys include the following.

[0062] In-Bi (In 66.3 mass%, Bi 33.7 mass%, melting point 72°C)

[0063] In-Bi (In 33.0 mass%, Bi 67.0 mass%, melting point 109°C)

[0064] ·In-Ag (In 97.0 mass%, Ag 3.0 mass%, melting point 145°C)

[0065] In addition, the indium alloy containing tin is defined as an indium alloy classified as a tin alloy.

[0066] From the perspective of obtaining higher reliability during high temperature and high humidity tests and thermal shock tests, the solder connection material may include at least one selected from the group consisting of In-Bi alloy, In-Sn alloy, In-Sn-Ag alloy, Sn-Au alloy, Sn-Bi alloy, Sn-Bi-Ag alloy, Sn-Ag-Cu alloy and Sn-Cu alloy.

[0067] The above-mentioned tin alloy or indium alloy can be selected according to the purpose of the solder connection material (temperature when used), etc. For example, if In-Sn alloy or Sn-Bi alloy is used, the electrodes can be welded to each other at below 150°C. When a material with a high melting point such as Sn-Ag-Cu alloy or Sn-Cu alloy is used, high reliability can be maintained even after being placed at high temperature.

[0068] The solder connection material may include one or more selected from Ag, Cu, Ni, Bi, Zn, Pd, Pb, Au, P and B. When the solder connection material includes Ag or Cu, the melting point of the solder connection material can be lowered to about 220° C., and the bonding strength with the electrode can be further improved, so that better conduction reliability can be easily obtained.

[0069] From the viewpoint of enabling mounting at low temperature, the melting point of the solder connection material may be, for example, 300° C. or less, 280° C. or less, 220° C. or less, 180° C. or less, 160° C. or less, 140° C. or less, or 80° C. or less. The melting point of the solder connection material is, for example, 70° C. or more. In this specification, the melting point of the solder connection material refers to the temperature (first endothermic peak temperature) at which the first endothermic peak (first endothermic peak) is generated when DSC measurement is performed in He gas flow at a heating rate of 10° C. / min using DSC (differential scanning calorimeter).

[0070] The solder connection material may be, for example, solder particles. The average particle size of the solder particles may be, for example, 1 to 500 μm. From the viewpoint of easily obtaining excellent conductivity, the average particle size of the solder particles may be 2 μm or more, or 3 μm or more, or 4 μm or more, or 5 μm or more. From the viewpoint of easily obtaining better connection reliability for micro-sized electrodes, the average particle size of the solder particles may be 400 μm or less, or 300 μm or less, or 200 μm or less, or 100 μm or less. From these viewpoints, the average particle size of the solder particles may be 2 to 400 μm, or 3 to 300 μm, or 4 to 200 μm, or 5 to 100 μm.

[0071] The average particle size of the solder particles can be measured using various methods that match the size. For example, methods such as dynamic light scattering, laser diffraction, centrifugal sedimentation, electrical detection band method, and resonance mass determination can be used. In addition, a method for measuring particle size based on images obtained by optical microscopes, electron microscopes, etc. can be used. As specific devices, flow-type particle image analysis devices, Microtrac, Coulter counters, etc. can be cited. In addition, the particle size of non-spherical solder particles can be the diameter of the circle circumscribed to the solder particles in the SEM image.

[0072] The adhesive is, for example, an insulating thermosetting adhesive. By using an insulating adhesive, the first circuit component and the second circuit component are bonded to each other, and the surrounding of the solder connection portion can be sealed by an insulating material. Therefore, the insulating adhesive can also be called a sealant. The adhesive contains, for example, a thermosetting component (for example, a combination of a thermosetting resin and a curing agent or a combination of a polymerizable compound and a thermal polymerization initiator, etc.). The polymerizable compound can be, for example, a free radical polymerizable compound. At this time, the thermal polymerization initiator can be a thermal free radical polymerization initiator. The free radical polymerizable compound can be a (meth) acrylic compound. Here, a (meth) acrylic compound refers to a compound having one or more acryloyl or methacryloyl groups. As a (meth) acrylic compound, for example, urethane (meth) acrylate, isocyanuric acid modified bifunctional (meth) acrylate, etc. can be cited. The thermal free radical polymerization initiator can be, for example, a peroxide. As peroxides, for example, peroxyesters such as 2,5-dimethyl-2,5-bis(2-ethylhexanoyl peroxy)hexane can be cited. The adhesive can further include flux components such as phosphoric acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, benzoic acid, and malic acid. For the purpose of improving the activity of the solder particle surface and the electrode surface, and finding the partial metal bonding between the solder particle interface and the electrode interface, and improving the effect of the close and wide contact interface with the solder particles, the adhesive can also further include a phosphate ester organic compound. As a phosphate ester organic compound, for example, compounds obtained by reacting anhydrous phosphoric acid with (meth) 2-hydroxyethyl acrylate or its 6-caprolactone addition polymer can be cited. The adhesive can further include inorganic filling materials such as silica fillers, film-forming materials such as polyester urethane resins, etc. The curing start temperature of the adhesive can be a temperature below the melting point of the solder connection material, or a temperature above the melting point of the solder connection material.

[0073] The first circuit component and the second circuit component may be the same as or different from each other. The first circuit component and the second circuit component may be a glass substrate or a plastic substrate (a plastic substrate composed of organic substances such as polyimide, polycarbonate, polyethylene terephthalate, cycloolefin polymer, etc.) on which circuit electrodes are formed; a printed wiring board; a ceramic circuit board; a flexible circuit board; an IC chip such as a driver IC, etc. Specifically, for example, it may be a printed wiring board (PWB) such as an FR-4 substrate, or it may be a flexible circuit substrate (FPC). The flexible circuit substrate may also be a flexible circuit substrate for COF installation (FPC for COF). The combination of the first circuit component and the second circuit component is not particularly limited, but for example, the first circuit component may be a printed wiring board (PWB) or a flexible circuit substrate (FPC), and the second circuit component may be a combination of a flexible circuit substrate (FPC) (including FPC for COF).

[0074] The first electrode is formed on a substrate (first substrate) constituting the first circuit component, and the second electrode is formed on a substrate (second substrate) constituting the second circuit component. The first substrate and the second substrate are, for example, substrates formed of inorganic substances such as semiconductors, glass, ceramics, organic substances such as polyimide, polycarbonate, glass / epoxy and other composites. Specifically, for example, in the case where the first circuit component is a printed wiring board, the first substrate can be a glass substrate, and in the case where the first circuit component is a flexible circuit substrate, the first substrate can be a polyimide film substrate. Similarly, in the case where the second circuit component is a printed wiring board, the second substrate can be a glass substrate, and in the case where the second circuit component is a flexible circuit substrate, the second substrate can be a polyimide film substrate. In addition, on one side of the first substrate (the side provided with the first electrode) and / or on one side of the second substrate (the side provided with the second electrode), an insulating layer is sometimes configured according to the circumstances.

[0075] The first electrode and the second electrode may be electrodes comprising metals such as gold, silver, tin, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, aluminum, molybdenum, titanium, nickel, oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), and indium gallium zinc oxide (IGZO). The first electrode and the second electrode may be electrodes formed by stacking two or more of these metals, oxides, etc. At this time, the first electrode and the second electrode may be composed of two layers or more than three layers. Specifically, for example, one or both of the first electrode and the second electrode may be an electrode (circuit electrode) having a Ni (nickel) plating layer and an Au (gold) plating layer stacked in sequence on a copper circuit (copper foil circuit), or an electrode (circuit electrode) having an Au (gold) plating layer stacked on a copper circuit (copper foil circuit). Furthermore, one of the first electrode and the second electrode may be an electrode (circuit electrode) having a Ni (nickel) plating layer and an Au (gold) plating layer sequentially stacked on a copper circuit (copper foil circuit), and the other may be an electrode having a Sn plating layer formed on a copper circuit (copper foil circuit) and having a Sn plating layer on the outermost surface. Such an electrode having a Sn plating layer on the outermost surface can be used as an electrode of a COF FPC.

[0076] The manufacturing method of the circuit connection structure of the above-mentioned embodiment can be implemented, for example, using a circuit connection device, wherein the circuit connection device comprises: a carrier, on which the first circuit component or the second circuit component is placed; a pressurizing means, which pressurizes the first circuit component and the second circuit component in opposite directions; a heating means, which heats at least one of the first circuit component and the second circuit component; and a cooling means, which cools the space between the first electrode and the second electrode in step (d). The pressurizing means and the heating means can be integrated, for example, a heating and pressing tool. The heating and pressing tool can use a known heating and pressing tool that has been used in circuit connection in the past. The cooling means can be, for example, an air cooling device, or the heating and pressing tool itself can have a cooling function.

[0077] In the following, the solder connection material is in the form of solder particles as an example, while referring to Figure 1 and Figure 2 , while describing in more detail each step in the method for manufacturing a circuit connection structure according to one embodiment.

[0078] (Step (a))

[0079] In step (a), a first circuit component 10 having a first substrate 11 and a first electrode 12, and a circuit connecting material 3 having solder particles (solder connecting material) 1 and an adhesive 2 are prepared, and the circuit connecting material 3 is arranged on the surface of the first circuit component 10 on which the first electrode 12 is formed (the surface 11a of the first substrate 11) (refer to Figure 1 (a) in the figure. ).

[0080] In step (a), the circuit connecting material 3 may be arranged on the first circuit component 10 in the form of a film containing solder particles 1 and binder 2, or in the form of a paste containing solder particles 1 and binder 2. When the circuit connecting material 3 is a film containing solder particles 1 and binder 2 (for example, an anisotropic conductive adhesive film), the circuit connecting material 3 can be arranged on the first circuit component 10 by lamination. In addition, after the film-shaped circuit connecting material 3 is arranged on the first circuit component 10, pressure may be applied to the circuit connecting material 3 to press-bond the circuit connecting material 3 and the circuit component 10. At this time, the circuit connecting material 3 may be heated at a temperature so low that the curing of the binder 2 is not performed.

[0081] The circuit connecting material 3 can be in a paste (liquid) or solid state at 25°C. Here, the circuit connecting material 3 being in a paste state at 25°C means that the viscosity of the circuit connecting material 3 at 25°C measured by an E-type viscometer is 400 Pa·s or less. In the case where the circuit connecting material 3 is in a paste state at 25°C, the circuit connecting material 3 can be arranged on the first circuit component 10 by directly applying the circuit connecting material 3 on the first circuit component. In the case where the circuit connecting material 3 is in a solid state at 25°C, in addition to heating it to make it into a paste and then using it, it can also be made into a paste using a solvent and then used. There is no particular limitation on the solvent that can be used as long as it is non-reactive with the components in the adhesive and has sufficient solubility.

[0082] (Step (b))

[0083] In step (b), the first circuit component 10 is disposed on the stage 51, and the second circuit component 20 having the second substrate 21 and the second electrode 22 is disposed on the first circuit component 10 in such a manner that the first electrode 12 and the second electrode 22 are opposed to each other (see Figure 1 (b) in FIG. 1 ). At this time, the second circuit component 20 may be disposed on the stage 51, and the first circuit component 10 may be disposed on the second circuit component 20 in such a manner that the first electrode 12 and the second electrode 22 are opposed to each other.

[0084] exist Figure 1 In (b), the circuit connecting material 3 and the second circuit component 20 are separated from each other, but the circuit connecting material 3 and the second circuit component 20 may be brought into contact with each other to obtain a laminate. Figure 1 Although step (b) is performed after step (a), the order of performing step (a) and step (b) is not particularly limited.

[0085] (Step (c))

[0086] In step (c), the first circuit component 10 and the second circuit component 20 are thermocompressed at a temperature above the melting point of the solder particles while the solder particles 1 are interposed between the first electrode 12 and the second electrode 22 (see Figure 1 (b) and (c) in the figure.

[0087] Step (c) includes, for example, heating the space between the first electrode 12 and the second electrode 22 to a temperature above the melting point of the solder particles, and applying pressure to the space between the first electrode 12 and the second electrode 22 in the opposing direction thereof. The first circuit component 10 and the second circuit component 20 are thermally pressed together by maintaining the space between the first electrode 12 and the second electrode 22 at a temperature above the melting point of the solder particles and in a pressurized state, thereby obtaining a pressed body 30.

[0088] The heating and pressurizing can be performed by heating and pressurizing one or both of the first circuit component 10 and the second circuit component 20. Figure 1 As shown in (c) in FIG. 1 , the heating and pressing tool 52 can be pressed on the second circuit component 20, and the second circuit component 20 can be moved toward the first circuit component 10 (toward the user). Figure 1 The heating and pressurizing may be performed by pressing the first circuit component 10 in the direction indicated by the arrow in (c), or the heating and pressurizing tool 52 may be pressed on the first circuit component 10 to press the first circuit component 10 toward the second circuit component 20 to perform heating and pressurizing.

[0089] The timing of heating and pressurizing is not particularly limited, and heating and pressurizing may be started simultaneously, or pressurizing may be started before heating or after heating. In step (c), heating may also be started before obtaining the above-mentioned laminate. For example, step (b) may be performed after step (a) and after heating of the circuit components arranged on the carrier is started.

[0090] The temperature during thermocompression bonding (thermocompression bonding temperature) is a temperature above the melting point of the solder connection material, and may be a temperature above the curing start temperature of the adhesive. The thermocompression bonding temperature may be set according to the melting point of the solder connection material. For example, when the melting point of the solder connection material is below 300°C, below 280°C, below 240°C, below 200°C, below 160°C, or below 80°C, the thermocompression bonding temperature may be set to below 330°C, below 300°C, below 280°C, below 240°C, below 200°C, or below 100°C, respectively. The lower limit of the thermocompression bonding temperature may be, for example, a temperature that is 10°C or higher than the melting point of the solder connection material. The thermocompression bonding temperature may be, for example, 80 to 330°C, 100 to 270°C, 140 to 230°C, or 140 to 200°C. Here, the thermocompression bonding temperature is a temperature reached between the first electrode 12 and the second electrode 22 when the thermocompression bonding is performed for a predetermined number of seconds, and is a value confirmed by the method described in the Examples.

[0091] The pressure during the thermocompression bonding may be 0.01 to 100 MPa, 0.1 to 20 MPa, or 0.5 to 10 MPa. Here, the pressure during the thermocompression bonding is the pressure per unit area during the thermocompression bonding for a predetermined number of seconds, and is a value confirmed by the setting value of the compression bonding device. In addition, the pressure during the thermocompression bonding is not necessarily constant, and may also vary within the above range.

[0092] The hot pressing time can be 1 to 1800 seconds, or 2 to 60 seconds or 3 to 30 seconds. Here, the hot pressing time is the time from the start of heating and pressurization to the start of cooling of step (d). In addition, the so-called start of cooling of step (d) refers to the time when cooling is started using a cooling means in step (d). When the cooling of step (d) is natural cooling, it refers to the time when heating is stopped. In addition, when cooling of step (d) is performed by changing the set temperature of the hot pressing tool in such a way that the temperature of the solder connection material becomes a temperature below the melting point of the solder connection material at the end of cooling, the time when the set temperature of the hot pressing tool is changed is set as the start of cooling of step (d). In the case of using both the change of the set temperature of the hot pressing tool and cooling using a cooling means, the time when cooling of either one is started is set as the start of cooling.

[0093] The crimped body 30 obtained in step (c) includes a molten material 4 of solder particles between the first electrode 12 and the second electrode 22. In addition, the crimped body 30 includes a region (cured material region) 5 composed of a cured material of the adhesive 2 between the first circuit component 10 and the second circuit component 20. Although not shown, the cured material region 5 may include uncured adhesive 2. The adhesive may not be completely cured in step (c). For example, the curing of the adhesive may be completed in step (d) or step (e) described later.

[0094] (Step (d))

[0095] In step (d), the temperature between the first electrode 12 and the second electrode 22 is lowered from a temperature higher than the melting point of the solder particles 1 to a temperature lower than the melting point of the solder particles 1, and the temperature is cooled while the pressure between the first electrode 12 and the second electrode 22 is applied (see Figure 2 (a) in the figure. ).

[0096] Cooling can be performed by stopping the heating between the first electrode 12 and the second electrode 22 (heating the crimping body 30) and naturally cooling the space between the first electrode 12 and the second electrode 22, but from the perspective of production efficiency, a cooling means may be used. Specifically, for example, Figure 2 As shown in (a) in FIG. 1 , a cooling device (eg, air cooling device) 53 may be used to cool the space between the first electrode 12 and the second electrode 22 (eg, air cooling).

[0097] The cooling time depends on the cooling method, but may be, for example, 0.5 to 1800 seconds, 1.0 to 600 seconds, or 2.0 to 150 seconds.

[0098] Step (d) can be implemented continuously from step (c). That is, after applying pressure between the first electrode 12 and the second electrode 22 in step (c), the cooling in step (d) can be implemented without releasing the pressure but maintaining the pressure. For example, when the pressurization in step (c) is performed using a heating and pressing tool 52, the heating and pressing tool 52 can be pressed on the circuit component (the first circuit component 10 or the second circuit component 20), and then the circuit component is pressed by the heating and pressing tool 52 until the temperature between the first electrode 12 and the second electrode 22 becomes a temperature below the melting point of the solder particle 1, thereby maintaining the first electrode 12 and the second electrode 22 in a pressurized state.

[0099] The pressure in step (d) may be the same as the range exemplified as the pressure during the thermocompression bonding in step (c). The pressure in step (d) may be implemented at a pressure lower than the pressure during the thermocompression bonding in step (c). The pressure in step (d) may be, for example, 0.01 to 100 MPa.

[0100] The pressurization in step (d) may be terminated immediately after the temperature between the first electrode 12 and the second electrode 22 becomes a temperature below the melting point of the solder connection material, or may be continued until the temperature between the first electrode 12 and the second electrode 22 becomes a temperature close to room temperature (e.g., 50° C. or below). When the pressurization is terminated at a temperature sufficiently higher than room temperature (e.g., 100 to 270° C.), step (e) of cooling the space between the first electrode 12 and the second electrode 22 without pressurizing may be performed.

[0101] The cooling in the step (e) can be carried out in the same manner as the cooling in the step (d).

[0102] According to the above method, we can obtain Figure 2 The circuit connection structure 40 shown in (b) in FIG. The circuit connection structure 40 comprises: a first circuit component 10; a second circuit component 20; and a circuit connection portion 7, which is disposed between the first circuit component 10 and the second circuit component 20, adheres the first circuit component 10 and the second circuit component 20 to each other, and electrically connects the first electrode 12 and the second electrode 22 to each other. The circuit connection structure 40 can be, for example, a circuit connection structure for a display input circuit, a semiconductor package, or a semiconductor sensor, or a circuit connection structure that serves as a connector instead of a circuit.

[0103] The circuit connection portion 7 includes: a region (cured material region) 5, which is composed of a cured material of the adhesive 2; and a solder connection portion 6, which is an electrode connection portion between opposing electrodes. The solder connection portion 6 is formed by melting and solidifying the solder particles 1, and is in close contact with the surfaces of the first electrode 12 and the second electrode 22 and in physical contact over a wide range to form a partial metal joint. In the circuit connection portion 7, a cured material region 5 is formed around the solder connection portion 6, and the solder connection portion 6 is sealed by the cured material of the adhesive 2. Figure 2 As shown in (b) in FIG. 1 , the solidified material region 5 may contain solder particles 1 (or their molten solidified materials) which are not used for connection.

[0104] The method for producing a circuit-connected structure according to one embodiment has been described above by taking as an example a method for producing a circuit-connected structure using solder particles as a solder connection material, but the method for producing a circuit-connected structure according to the present invention is not limited to the above.

[0105] For example, the solder connection material may be a solder bump. Figure 31 is a cross-sectional view schematically showing a method for manufacturing a circuit connection structure using a solder bump as a solder connection material. In the method using a solder bump as a solder connection material, first, a circuit component 115 with a solder bump is prepared in which a solder bump 101 is formed on a first electrode 112 of a first circuit component 110 (see FIG. 1 ). Figure 3 Next, the adhesive 102 and the second circuit component 120 are arranged on the surface of the circuit component 115 with solder bumps on which the solder bumps 101 are formed (see Figure 3 (b) in the figure. ). At this time, the second circuit component 120 is arranged in such a manner that the first electrode 112 and the second electrode 122 are opposed to each other via the adhesive 102. Thus, the step (a) of arranging the circuit connection material 103 having the solder bump 101 and the adhesive 102 as the solder connection material on the surface of the first circuit component 110 (the surface 111a of the first substrate 111) on which the first electrode 112 is formed, and the step (b) of arranging the second circuit component 120 on the first circuit component 110 in such a manner that the first electrode 112 and the second electrode 122 are opposed to each other are completed. Next, the steps (c), (d), and, if necessary, the step (e) are carried out in the same manner as in the case of using solder particles, thereby obtaining Figure 3 The circuit connection structure 140 shown in (c) .

[0106] The solder bump 101 can be formed, for example, by heating (heating and pressurizing, if necessary) solder particles on the first electrode 112 to melt the solder particles and then cooling and solidifying the solder particles.

[0107] The adhesive 102 can be used in a film form or in a paste form. The method of configuring the adhesive 102 on the first circuit component 110 is not particularly limited. For example, when the adhesive 102 is in a film form, the adhesive 102 can be configured by laminating on the circuit component 115 with solder bumps. In addition, when the adhesive 102 is in a paste form at 25°C, the adhesive 102 can be configured on the first circuit component 10 by directly applying the adhesive 102 on the circuit component 115 with solder bumps. When the adhesive 102 is solid at 25°C, in addition to heating it to make it into a paste and then using it, it can also be made into a paste using a solvent and then used. As a solvent that can be used, there is no particular limitation as long as it is a solvent that has no reactivity with the components in the adhesive and shows sufficient solubility.

[0108] The adhesive 102 may be placed in advance on the surface of the second circuit member 120 (the surface 121a of the second substrate 121) on which the second electrode 122 is formed. In this case, the step (a) is completed by performing the step (b).

[0109] exist Figure 3In the illustrated method, the adhesive 102 is disposed on the circuit component 115 with the solder bumps. However, the solder bumps 101 may be formed after the adhesive 102 is disposed on the first circuit component 110 .

[0110] Example

[0111] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

[0112] <Example 1>

[0113] (Preparation process)

[0114] [Preparation of solder particles]

[0115] Solder particles (trade name: Sn72Bi28Type 5) manufactured by MITSUI MINING & SMELTING CO., LTD. were classified to remove solder particles with a particle size of 15 μm or less and solder particles with a particle size of 25 μm or more, thereby obtaining solder particles A (Bi content: 28 mass%, Sn content: 72 mass%, average particle size: 20 μm, melting point: 139°C). The average particle size of solder particles A was confirmed by measuring the D50 value of solder particles A using a micro-tracking measurement device. The melting point of the solder particles was calculated based on the value of the first endothermic peak in DSC. The DSC measurement of the solder particles was performed using a differential scanning calorimeter (trade name: Q-1000) manufactured by TA Instruments at a heating rate of 10°C / min in a He gas flow within a range of 30 to 200°C.

[0116] [Preparation of coating solution]

[0117] 5 parts by mass of urethane acrylate (product name: UN-952, manufactured by Negami Chemical Industrial Co., Ltd.) and 10 parts by mass of isocyanuric acid EO-modified diacrylate (product name: M-215, manufactured by TOAGOSEI CO., LTD.) as radical polymerizable compounds, 2 parts by mass of a reaction product of a 6-caprolactone addition polymer of 2-hydroxyethyl methacrylate and anhydrous phosphoric acid (product name: PM-21, manufactured by Nippon Kayaku Co., Ltd.) as a phosphate ester organic compound, 3 parts by mass of a peroxyester (product name: PERHEXA250, manufactured by NOF CORPORATION) as a thermal radical generator, 15 parts by mass of a silica filler (product name: AEROSIL R202, manufactured by NIPPON AEROSIL CO., LTD.) as an inorganic filler, and 15 parts by mass of a polyester urethane resin (product name: UR8240, manufactured by TOYOBO CO., LTD.) were mixed and stirred in methyl ethyl ketone to obtain a solution A.

[0118] The solder particles A obtained above were dispersed in solution A. At this time, the amount of solder particles A added was 30 parts by mass based on 100 parts by mass of nonvolatile components (components other than methyl ethyl ketone) in solution A. Thus, a coating liquid for forming a film-like circuit connection material was obtained.

[0119] [Formation of Film-like Circuit Connection Material]

[0120] The coating liquid obtained above was applied to a polyethylene terephthalate (PET) film (thickness: 50 μm) with a demolding treatment on one side using a coating device. The coating film was dried by hot air drying at 70°C to form an anisotropically conductive film-like circuit connection material (thickness: 25 μm) on the PET film, thereby obtaining a film-like circuit connection material with a removable substrate. In addition, the thickness of the film-like circuit connection material was measured using a laser microscope. Specifically, a portion of the film-like adhesive on the PET film was removed, and the height from the exposed portion of the surface of the PET film to the surface of the film-like adhesive was measured to determine the thickness of the film-like circuit connection material.

[0121] (Step (a))

[0122] As an adherend imitating a circuit component, a first circuit component having a gold electrode (10mm×5mm, single electrode) disposed on the surface of a ceramic substrate was prepared. Next, the film-like circuit connection material with a strippable substrate obtained in the above was cut into a width of 1.5mm and attached to the gold electrode of the first circuit component from the side of the film-like circuit connection material. Next, a thermocompression bonding device (heating method: constant heat type, Nikka Equipment Engineering Co., Ltd. system) was used to thermocompress the film-like circuit connection material and the first circuit component, and a laminated body in which a film-like circuit connection material was disposed on the first circuit component was obtained. Specifically, the first circuit component of the film-like circuit connection material with a strippable substrate was arranged on a carrier in a manner that the PET film side was facing upward, and the heating and pressing tool was pressed on the PET film, thereby heating the film-like circuit connection material while pressurizing it. The thermocompression bonding time (pressing time) was set to 1 second, and the pressure was set to 1MPa relative to the total area (area of ​​the bonding part) of the film-like circuit connection material. The temperature of the heating and pressing tool was adjusted so that the final temperature of the film-like circuit connecting material was 70° C. The final temperature of the film-like circuit connecting material was measured by inserting a thermocouple in the film-like circuit connecting material. The PET film was peeled off after the laminate returned to room temperature (25° C.).

[0123] (Step (b))

[0124] As the second circuit component, a flexible circuit board (FPC) having a circuit electrode with Ni / Au electroplating treatment on a copper circuit with a line width of 100 μm, a pitch of 200 μm, and a thickness of 35 μm was prepared. Then, the second circuit component was placed on the laminated body in such a manner that the gold electrode of the first circuit component and the circuit electrode of the second circuit component in the laminated body obtained above were opposite to each other, thereby obtaining a laminated body in which a film-like circuit connection material and the second circuit component were provided on the first circuit component.

[0125] (Step (c))

[0126] Next, a thermocompression bonding device (heating method: pulse heating type, manufactured by OHASHI ENGINEERING Co., Ltd.) was used to thermocompress the first circuit component and the second circuit component. Specifically, the laminate obtained in step (b) was placed on a carrier with the second circuit component side facing upward, and the heating and pressing tool was pressed on the second circuit component, thereby heating and pressing the second circuit component. The thermocompression bonding time (the time from the contact between the heating and pressing tool and the second circuit component to the start of cooling of step (d)) was set to 8 seconds, and the pressure was set to 1 MPa relative to the total area of ​​the film-like circuit connection material (the area of ​​the bonding part). The temperature of the heating and pressing tool was adjusted in such a way that the reaching temperature between the opposing electrodes became 155°C. The reaching temperature between the opposing electrodes was measured by inserting a thermocouple into the film-like circuit connection material.

[0127] (Step (d))

[0128] Next, while the heating and pressing tool is pressed on the second circuit component, the heating by the heating and pressing tool is stopped and the crimped body is cooled (e.g., air-cooled). The pressure during cooling is set to 1 MPa relative to the total area (the area of ​​the bonding portion) of the film-like circuit connection material. When the temperature between the opposing electrodes cools to 120°C, the heating and pressing tool is separated from the second circuit component. The time required from the start of cooling until the temperature between the opposing electrodes reaches 120°C is 50 seconds.

[0129] (Step (e))

[0130] The cooling in step (d) was continued until the temperature between the opposing electrodes reached a temperature close to room temperature (50° C. or less), thereby obtaining the circuit connection structure of Example 1. Figure 4 A graph (temperature-pressure distribution) showing the relationship between the time, the temperature between the electrodes, and the pressure from the start of heating and pressing in step (c) to the acquisition of the circuit connection structure is shown. Figure 4 The temperature distribution in the figure represents the measured value, and the pressure distribution represents the device setting value.

[0131] <Comparative Example 1>

[0132] After the preparation step to step (c) are performed in the same manner as in Example 1, steps (d) and (e) are not performed. After the heating and pressing tool contacts the second circuit component, the heating and pressing tool is separated from the second circuit component after 8 seconds to terminate the heat pressing. The pressed body is placed at room temperature (25°C) for cooling, thereby obtaining the circuit connection structure of Comparative Example 1. Figure 5Graph (temperature-pressure distribution) showing the relationship between the time, the inter-electrode temperature, and the pressure from the start of heating and pressing in step (c) until the circuit connection structure is obtained is shown.

[0133] <Comparative Example 2>

[0134] A circuit connection structure of Comparative Example 2 was obtained in the same manner as Comparative Example 1 except that the thermal compression bonding time (the time during which the heating and pressing tool is brought into contact with the second circuit component) in step (c) was changed to 60 seconds. Figure 6 Graph (temperature-pressure distribution) showing the relationship between the time, the inter-electrode temperature, and the pressure from the start of heating and pressing in step (c) until the circuit connection structure is obtained is shown.

[0135] <Evaluation>

[0136] Confirm the presence or absence of cracks in the inter-electrode connection part (solder connection part) in the circuit connection structure produced in Example 1 and Comparative Examples 1 to 2. Specifically, first, the circuit connection structure was clamped between two pieces of glass (thickness: about 1 mm), and a resin composition consisting of 100 g of bisphenol A epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of a curing agent (trade name: Epomount curing agent, manufactured by Refine Tec Ltd.) was injected. Then, the injection molded object was ground using a grinder, thereby exposing a cross-section containing the inter-electrode connection part parallel to the connection direction of the circuit connection structure. Then, a scanning electron microscope (SEM, trade name: SE-8020, manufactured by Hitachi High-Tech Corporation.) was used to observe the exposed cross-section, and the presence or absence of cracks in the inter-electrode connection part was observed. In the case where there is a crack with a length of 30% or more relative to the particle size of the solder particles observed in the cross-sectional observation, it is judged that there is a crack. As a result, cracks were observed in Comparative Examples 1 and 2, but in Example 1, cracks were not observed.

[0137] Explanation of symbols

[0138] 1-solder particles (solder connection material), 2, 102-adhesive, 3, 103-circuit connection material, 5-cured area, 6-solder connection part, 10, 110-first circuit component, 11, 111-first substrate, 11a, 111a-surface of the first substrate (the surface of the first circuit component on which the first electrode is formed), 12, 112-first electrode, 20, 120-second circuit component, 21, 121-second substrate, 22, 122-second electrode, 30-crimped body, 40, 140-circuit connection structure, 51-carrier, 52-heating and pressurizing tool, 53-cooling device, 101-solder bump (solder connection material), 115-circuit component with solder bump.

Claims

1. A method for manufacturing a circuit connection structure, comprising: Step (a), disposing a circuit connection material including a solder connection material and an adhesive on a surface of a first circuit component having a first electrode on which the first electrode is formed; Step (b), disposing a second circuit component having a second electrode on the first circuit component in such a manner that the first electrode and the second electrode face each other; Step (c), in a state where a solder connection material is interposed between the first electrode and the second electrode, thermally pressing the first circuit component and the second circuit component at a temperature higher than the melting point of the solder connection material; and In step (d), the temperature between the first electrode and the second electrode is lowered from a temperature higher than the melting point of the solder connection material to a temperature lower than the melting point of the solder connection material, and the temperature is cooled while applying pressure between the first electrode and the second electrode.

2. The manufacturing method according to claim 1, wherein: The solder connection material is solder particles.

3. The manufacturing method according to claim 2, wherein: In the step (a), the circuit connecting material is disposed on the first circuit member in the form of a film including the solder particles and the binder.

4. The manufacturing method according to claim 2, wherein: In the step (a), the circuit connecting material is disposed on the first circuit member in a paste state including the solder particles and the binder.

5. The manufacturing method according to any one of claims 1 to 4, wherein: The melting point of the solder connection material is below 300°C, The thermocompression bonding temperature in the step (c) is 330° C. or lower.

6. A circuit connection device, used in the manufacturing method according to any one of claims 1 to 5, the circuit connection device comprising: a carrier, mounting the first circuit component or the second circuit component; A pressurizing means for pressurizing the first circuit component and the second circuit component in opposite directions; Heating means for heating at least one of the first circuit component and the second circuit component; and A cooling means for cooling between the first electrode and the second electrode in the step (d).

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