JP2001345017A - Electro-conductive jointing material and component mounting method and electronic circuit unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electro-conductive jointing material, a component mounting method, and an electronic circuit unit wherein the heat deterioration of electronic parts, curvature deformation of a printed-circuit board or the like can be reduced. SOLUTION: The electro-conductive jointing material 10 is composed of fused electro- conductive particles 13 which has a core 13A that is composed of a shape memory material having a transformation start temperature of 200 deg.C or less and is developed and deformed at the transformation start temperature or more and a low melting metal 13B having a melting point of 200 deg.C or less surrounding the core 13A, and which is kneaded into a paste with a resin binder 11 together with electro-conductive particles 12. The component mounting method comprises the first temperature retaining process H1 in order that the low melting metal 13B of the fused electro-conductive particles 13 is fused at a temperature of 200 deg.C or less and the second temperature retaining process H2 in order that the core 13A of the fused electro-conductive particles 13 is developed and deformed at a temperature of 200 deg.C or less. The electronic circuit unit 1 is constituted so that an electro-conductive paste (the electro-conductive bonding material) 10 is used to mount the electronic parts on the printed-circuit board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive bonding material obtained by kneading conductive particles into a resin binder which cures through a heating step, and prints and connects electronic parts using the conductive bonding material. The present invention relates to a component mounting method for mounting on a substrate, and further relates to an electronic circuit unit formed by mounting an electronic component on a printed wiring board using the conductive bonding material.

[0002]

2. Description of the Related Art Conventionally, as a method of mounting an electronic component on a printed wiring board, a reflow mounting method using a solder paste, that is, after printing and supplying a solder paste to an electrode of the printed wiring board via a metal mask, A method of mounting an electronic component at a predetermined position on a printed wiring board and heating and melting a solder paste in a reflow furnace to connect electrodes of the electronic component and electrodes of the printed wiring board to each other has been adopted.

[0003] However, in the mounting method using the solder paste, there is a disadvantage that the lead component contained in the solder paste adversely affects the human body and the global environment.

[0004] As a method of mounting an electronic component to solve such a problem, a lead-free solder paste containing no lead component or a conductive paste (conductive bonding material) obtained by kneading conductive particles such as copper in a resin binder is used. There is provided a method of connecting electrodes of an electronic component and electrodes of a printed wiring board to each other.

[0005] In these mounting methods using a lead-free solder paste or a conductive paste, the electronic components can be mounted on the printed wiring board by the same operation steps as the mounting method using the solder paste described above.

[0006]

By the way, in the above-mentioned method of mounting an electronic component on a printed wiring board using a lead-free solder paste, heating and melting of the lead-free solder paste in a reflow furnace is performed at 200 ° C. or more. Therefore, there has been an inconvenience of causing a mounting failure due to thermal deterioration of the electronic component or warpage of the printed wiring board.

On the other hand, in the method of mounting an electronic component on a printed wiring board using a conductive paste, the heating and melting of the conductive paste in a reflow furnace is performed at a temperature of 200 ° C. or less. The warpage of the wiring board can be reduced.

On the other hand, in the above-mentioned conductive paste,
Since the electrical connection between the electrodes of the electronic component and the electrodes of the printed wiring board is made by relaying a large number of conductive particles kneaded in a resin binder, the electrical connection is made in comparison with the mounting method using a lead-free solder paste. Electrical conduction performance is inferior.

To solve the above problem, there is a method of forming the conductive particles in the conductive paste from a material having a high electric conductivity such as gold or silver. However, since the gold or silver is expensive, the cost is reduced. There was an inconvenience that caused inconvenience in terms of surface.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to reduce the thermal degradation of electronic components and the warpage of a printed wiring board, and to achieve good electrical conduction performance without inconvenience in cost. And a component mounting method for mounting an electronic component on a printed wiring board using the conductive bonding material, and mounting the electronic component on a printed wiring board using the conductive bonding material An electronic circuit unit is provided.

[0011]

The conductive bonding material according to the present invention is a conductive bonding material comprising a resin binder which is cured through a heating step, and conductive particles kneaded in the resin binder. A core formed of a shape memory material having a transformation start temperature of 200 ° C. or lower, and expanded and deformed at a transformation start temperature or higher, and a fused conductive particle having a low melting point metal having a melting point of 200 ° C. or lower including the core, It is configured by kneading the resin binder with the conductive particles.

Further, in the component mounting method according to the present invention, there is provided a supplying step of supplying a conductive bonding material to a printed wiring board, and mounting an electronic component at a predetermined position on the printed wiring board via the conductive bonding material. And a heating step of heating the conductive bonding material, a component mounting method of mounting an electronic component on the printed wiring board via the conductive bonding material, wherein the resin is cured through the heating step. With a binder,
A core formed of a shape memory material having a transformation start temperature of 200 ° C. or lower and being expanded and deformed at a transformation start temperature or higher; and a low melting point containing the core having a melting point of 200 ° C. or lower. Using a conductive bonding material obtained by kneading molten conductive particles having a melting point metal with the resin binder together with the conductive particles, and in the heating step, melting the low melting point metal of the molten conductive particles. A temperature holding step at 200 ° C. or lower,
2 for expanding and deforming the core of the molten conductive particles
A temperature holding step at a temperature of 00 ° C. or less.

An electronic circuit unit according to the present invention is an electronic circuit unit comprising an electronic component mounted on a printed wiring board via a conductive bonding material, wherein the electronic circuit unit comprises a resin binder cured through the heating step, A conductive particle kneaded in the resin binder, and having a transformation start temperature of 2
A core formed of a shape memory material of 00 ° C. or lower and expanded and deformed at a transformation starting temperature or higher, and a molten conductive particle including a low melting point metal having a melting point of 200 ° C. or lower including the core, the conductive particles together with the conductive particles, The electronic component is mounted on the printed wiring board using a conductive bonding material kneaded with a resin binder.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing embodiments. FIG. 1 shows an embodiment of an electronic circuit unit according to the present invention manufactured by the component mounting method according to the present invention using the conductive bonding material according to the present invention.

As shown in FIG. 1, an electronic circuit unit 1 of the present invention includes a printed wiring board 2 and electronic components 3 and 4, and uses a conductive paste (conductive bonding material) 10 to perform printed wiring. It is configured by mounting electronic components 3 and 4 on a substrate 2.

Here, on the surface of the printed wiring board 2, the electrodes 2A are provided at predetermined positions where the electronic components 3 and 4 are mounted.
Are formed, and the surfaces other than those on which the electrodes 2A are formed are covered with a resist film 2R. Electronic components 3 and 4 are provided on each electrode 2A of the printed wiring board 2.
Are mechanically and electrically joined via the conductive paste 10.

FIG. 2 shows an embodiment of the conductive paste (conductive bonding material) according to the present invention.
And the molten conductive particles 13 are kneaded.

The resin binder 11 constituting the conductive paste 10 is a thermosetting resin containing epoxy as a main component, and has a paste shape at normal temperature (room temperature of about 20 ° C.). The conductive particles 12 constituting the conductive paste 10 are made of Cu (copper) fine particles in view of cost and electric conductivity. Here, the resin binder 11
As the above, other than the epoxy-based, phenol-based or unsaturated polyester-based thermosetting resin can also be adopted, and also polyethylene-based, polyvinyl chloride-based, polystyrene-based, polymethyl methacrylate-based, polyamide-based, A thermoplastic resin such as a fluororesin type, a polycarbonate type, a polyester type, and a silicone type can also be adopted, and the resin binder 11 can also be constituted by a mixture of the above-described thermosetting resin and thermoplastic resin. .

Each of the above-mentioned resin materials has a capacity of 20.
It is cured by passing through a heating step in a temperature range of 0 ° C. or lower. In other words, as long as it is cured through the above-mentioned heating step, various resin materials can be used regardless of thermosetting or thermoplasticity. 11 can be adopted.

If the cost is the same as that of the Cu (copper) fine particles and has sufficient electric conductivity, Cu (copper)
Needless to say, the conductive particles 12 can be formed by other appropriate metal fine particles.

As shown in FIG. 3, the molten conductive particles 13 constituting the conductive paste 10 include a core 13A made of a shape memory alloy (shape memory material) and a low melting point metal 13B including the core 13A. ing.

The core 13A has a transformation start temperature of 200
Cu (copper) -based shape memory alloy below ℃, more specifically Cu-Mn-Al
It is a pin-shaped member formed from a (copper-manganese-aluminum) -based shape memory alloy, and at room temperature (room temperature around 20 ° C.)
In FIG. 4A, while being condensed and deformed into two as shown in FIG. 4A, in a temperature region equal to or higher than the transformation start temperature, it is expanded and deformed into a substantially linear shape as shown in FIG. 4B. .

On the other hand, as the low melting point metal 13B, a Ga-Al (gallium-aluminum) alloy having a melting point of 200 ° C. or less is employed. At room temperature (room temperature of about 20 ° C.), as shown in FIG. The molten conductive particles 13 are formed by covering the deformed core 13A.

The core 13 of the fused conductive particles 13
A is not only the above-mentioned Cu (copper) based shape memory alloy, but also T
Transformation onset temperature of 20 such as i (titanium) based shape memory alloy (specific example: Ti-Ni (titanium-nickel) based shape memory alloy)
It is possible to employ various shape memory alloys of 0 ° C. or less.

The low melting point metal 13 of the molten conductive particles 13
Examples of B include not only the Ga-Al (gallium-aluminum) alloy described above, but also Ga (gallium) and In (indium).
Single metal such as, or Ga (gallium) or In (indium), Al (aluminum), P (phosphorus), As (arsenic), A
It has sufficient conductivity, such as an alloy with a metal selected from n (antimony) and Bi (bismuth), and has a melting point of 20.
It goes without saying that various low-melting metals can be adopted as long as they are low-melting metals of 0 ° C. or lower.

As shown in FIG. 5, an electronic circuit unit 1 according to the present invention includes a conductive paste applying step (supplying step) S1 for supplying a conductive paste 10 to a printed wiring board 2, and an electronic component 3, 4 for connecting the electronic components 3, 4 to the printed wiring board. An electronic component mounting step (mounting step) S2 for mounting the electronic components 3 and 4 on the printed wiring board 2;
It is manufactured through a heating step S3 for heating 0.

As shown in FIG. 6A, a conductive paste application step (S1) is applied to the printed wiring board 2 inserted into a mounting line (not shown) of a production facility as shown in FIG. 6B. , A conductive paste 10 is printed and supplied to the surface of each electrode 2A of the printed wiring board 2 via a metal mask M by a squeegee Q.

The supply of the conductive paste 10 to each electrode 2A of the printed wiring board 2 is performed by the above-described metal mask M.
Not only printing and supply using a squeegee and a squeegee Q, but also a method of spraying and supplying the conductive paste 10 by a well-known ink jet method adopted in a printing apparatus, a method of applying and measuring the conductive paste 10 by a well-known dispenser It is possible to adopt various supply methods.

After supplying the conductive paste 10 to each electrode 2A of the printed wiring board 2, as shown in FIG. 6C, in the electronic component mounting step (S2), the electrodes 3A and 4A of the electronic components 3 and 4 are removed. The electronic components 3 and 4 are mounted at predetermined positions with respect to the printed wiring board 2 with the conductive paste 10 placed on each of the electrodes 2A to which the conductive paste 10 is supplied.

Thereafter, as shown in FIG.
In (S3), the conductive paste 10 is heated in the reflow furnace F with the electronic components 3 and 4 mounted on predetermined positions of the printed wiring board 2.

The heating step (S3) is performed by selecting any one of an air atmosphere, an inert gas atmosphere, and a vacuum atmosphere. Further, the heating step (S3) can be carried out using not only a reflow furnace but also an oven.

FIG. 7 shows the temperature profile of the heating step (S3). As shown in this temperature profile, the heating step
(S3) is a first temperature holding step H1, a second temperature holding step H
And a third temperature holding step H3. After the third temperature holding step H3, the temperature is cooled to room temperature by cooling.

In the first temperature holding step H1, the conductive paste 1
This is a step of melting the low-melting-point metal 13B in the 0 molten conductive particles 13, and is maintained in a temperature range of 29.78 ° C. to 50 ° C. for about 20 seconds.

In the second temperature holding step H2, the conductive paste 1
This is a step of developing and deforming the core 13A of the molten conductive particles 13 of the temperature 0, and is maintained for about 30 seconds in a temperature range of 100 ° C. to 150 ° C.

In the third temperature holding step H3, the conductive paste 1
This is a step of thermally curing the resin binder 11 of No. 0.
It is held for about 100 seconds in the temperature range of ℃ to 200 ℃.

The first temperature holding step H1, the second temperature holding step H2, and the third temperature holding step H3 of the heating step (S3) are not limited to the temperature profile shown in FIG. Of course, it can be set arbitrarily based on the materials of the low melting point metal 13B, the core 13A, the resin binder 11, and the like.

After the above-described heating step (S3), the resin binder 11 of the conductive paste 10 is heated and hardened, so that the electrodes 2A of the printed wiring board 2 and the electrodes 3A, 4A of the electronic components 3, 4 are formed. Conductive paste 10
The electronic circuit unit 1 is completed by mounting the electronic components 3 and 4 on the printed wiring board 2 as shown in FIG. 6D.

FIG. 8A shows the electrodes 2A of the printed wiring board 2 and the electrodes 3A of the electronic component 3 immediately after the electronic component mounting step (S2) and before the heating step (S3).
2 shows the state of the conductive paste 10 interposed between the first and second conductive pastes.

In this state, when the above-described heating step (S3) is performed, in the first temperature holding step (H1), the low melting point metal 13B in the molten conductive particles 13 of the conductive paste 10 is formed.
Melts.

Next, in the second temperature holding step (H2), the core 13A of the molten conductive particles 13 of the conductive paste 10 is condensed and deformed as shown in FIG. It expands and deforms into a linearly extended shape.

At this time, the low melting point metal 13B already melted in the first temperature holding step (H1) is spread by the core 13A which expands and deforms as described above, and exists around the molten conductive particles 13. It penetrates between many conductive particles 12.

Thereafter, in a third temperature holding step (H3), the resin binder 11 of the conductive paste 10 is thermoset,
The electrode 2A and the electrode 3A are mechanically joined by the resin binder 11 and are electrically connected through a large number of conductive particles 12.

FIG. 8B shows the state of the conductive paste 10 in the electronic circuit unit 1 completed after the heating step (S3), which was spread in the above-mentioned second temperature holding step (H2). The low-melting-point metal 13B comes into contact with a large number of conductive particles 12 existing around the dissolved conductive particles 13.
(Metal-to-metal bonding).

Here, the low melting point metal 13B is in contact with a wide area of the surface of the surrounding conductive particles 12, so that the low melting point metal 13B is interposed.
Many conductive particles 12 are connected to each other with good conductivity.

As described above, the conductive particles 12 are satisfactorily conducted by the interposition of the low melting point metal 13B, so that the conductive particles are not formed from a material having a high electric conductivity such as gold or silver. The electric conduction performance of the conductive paste 10 is improved without causing an increase in the electric current, and the connection between the electrode 2A of the printed wiring board 2 and the electrode 3A of the electronic component 3 is improved without causing a disadvantage in cost. It is to be performed with a proper conduction performance.

Further, depending on the position and posture of the molten conductive particles 13 before the heating step (S3), the low melting point metal 13B melted in the heating step (S3) directly contacts the electrodes 2A and 3B (intermetallic bonding). ), And in such a situation, the electrical conduction performance between the electrode 2A and the electrode 3A is further improved.

Although only the connection between the printed wiring board 2 and the electronic component 3 has been described with reference to FIG. 8, the printed wiring board 2 and the electronic component 3 are also connected to the printed wiring board 2 and the electronic component 4. It is needless to say that they are connected to each other in the same manner as the above connection.

As is clear from the temperature profile of the heating step (S3) shown in FIG. 7, the heating step (S3)
Is performed within a temperature range of 200 ° C or less,
Needless to say, it is possible to prevent as much as possible the occurrence of defective mounting due to the thermal deterioration of the electronic components 3 and 4 and the warpage of the printed wiring board 2.

Further, as the resin binder in the above-mentioned conductive paste, a negative thermal expansion material (for example, a small piece of a polyfluoroethylene fiber) is kneaded with an epoxy-based thermosetting resin, and heat-shrinks in a heating step. It is also possible to employ a resin.

According to such a configuration, the conductive paste is thermally shrunk in the heating step to reduce the distance between the conductive particles to several nanometers or less, thereby improving the electrical continuity between the conductive particles. This makes it possible to further improve the electrical conduction performance of the conductive paste.

FIG. 9 shows another embodiment of the molten conductive particles in the conductive paste (conductive bonding material) according to the present invention. The molten conductive particles 13 'are made of a shape memory alloy and condensed and deformed. Core 13A 'and this core 13
A low melting point metal 13B 'containing A' and a flux material 13C 'covering the low melting point metal 13B'.

That is, the molten conductive particles 13 'have the same structure as the previously described molten conductive particles 13 (see FIG. 3) except that the surface is covered with a flux material 13C'. The configuration of the conductive paste formed by kneading the particles 13 'is also the same as the conductive paste 10 described above (see FIG. 2).
There is basically no change.

In the conductive paste containing the above-mentioned fused conductive particles 13 ′, the low melting metal 13
The formation of oxide is prevented by covering the surface of B ′ with the flux 13C ′, and electrical conduction between the low melting point metal 13B ′ and the surrounding conductive particles (see reference numeral 12 in FIG. The melting point metal 13B 'and each electrode (reference 2A in FIG.
3A) is good.

In addition, since a part of the flux 13C 'prevents the formation of oxides on the surrounding conductive particles (see reference numeral 12 in FIG. 8B), the electrical conduction between the conductive particles is good. As a result, it is possible to prevent a decrease in the electrical conduction performance due to the generation of the oxide.

The core 13A of the molten conductive particles 13 in the conductive paste 10 and the molten conductive particles 1
The core 13A 'in 3' is a pin-shaped member formed of a shape memory alloy, and is condensed and deformed in two at normal temperature (room temperature). Time) is not limited to the above-described embodiment, and it goes without saying that various modes can be adopted.

For example, the core is formed by winding a rod material like a coil spring, crushed and condensed and deformed like a coil spring compressed at normal temperature, and developed and deformed into a shape like a coil spring extended in a temperature region higher than the transformation start temperature. It is also possible to configure so that the

[0057]

As described in detail above, the conductive bonding material of the present invention is a conductive bonding material comprising a resin binder which cures through a heating step and conductive particles kneaded in the resin binder. Molten conductive particles having a core formed of a shape memory material having a transformation start temperature of 200 ° C. or lower and expanding and deforming at a transformation start temperature or higher, and a low-melting metal containing the core and having a melting point of 200 ° C. or lower. Is kneaded together with the conductive particles into the resin binder. According to the conductive bonding material having the above configuration, when mounting the electronic component on the printed wiring board, the heating and melting of the conductive bonding material in the reflow furnace are performed at 200 ° C. or lower, so that the thermal deterioration and printing of the electronic component are performed. Mounting defects due to warpage of the wiring board and the like are reduced as much as possible. Further, according to the conductive bonding material having the above configuration, in the heating step of mounting the electronic component on the printed wiring board, the low melting point metal of the molten conductive particles is spread by the core of the molten conductive particles that expands and deforms. Then, it comes into contact with a large number of conductive particles existing around the dissolved conductive particles (intermetallic bonding). Thereby, the electrical conduction performance of the conductive bonding material can be improved without forming conductive particles from a material having high electrical conductivity such as gold or silver, and the conductive bonding material according to the present invention can be improved. Thus, good electrical conduction performance can be obtained without inconvenience in terms of cost.

Further, in the component mounting method of the present invention, a supplying step of supplying a conductive bonding material to the printed wiring board, and mounting the electronic component at a predetermined position on the printed wiring board via the conductive bonding material. A mounting step, through a heating step of heating the conductive bonding material, a component mounting method of mounting an electronic component on the printed wiring board via the conductive bonding material, and a resin binder cured through the heating step A core comprising a shape memory material having a transformation start temperature of 200 ° C. or lower, which expands and deforms at a transformation start temperature or higher, and a melting point including the core having a melting point of 200 ° C. or lower, comprising conductive particles kneaded in the resin binder. A conductive bonding material obtained by kneading molten resin particles having a low melting point metal with the resin binder together with the conductive particles; And it includes a temperature holding step at 200 ° C. or less for melting the low melting point metal of conductive particles, and a temperature holding step at 200 ° C. or less for deploying deform the core of the molten conductive particles. According to the component mounting method having the above configuration, when mounting the electronic component on the printed wiring board, the heating and melting of the conductive bonding material in the reflow furnace and the respective temperature holding steps are performed at 200 ° C. or less. Mounting defects due to thermal deterioration and warpage of the printed wiring board are reduced as much as possible. Further, according to the component mounting method having the above configuration, in the temperature holding step in the heating step when mounting the electronic component on the printed wiring board, the low melting point metal of the molten conductive particles is melted, and the molten low melting point metal is melted. Expanded by the core of molten conductive particles that expand and deform,
It comes into contact with a large number of conductive particles existing around the dissolved conductive particles (intermetallic bonding). Thereby, without forming conductive particles from a material having high electrical conductivity such as gold or silver, the electrical conduction performance in the conductive bonding material is improved, and according to the component mounting method according to the present invention, Good electrical continuity between the printed wiring board and the electronic component can be obtained without inconvenience in cost.

The electronic circuit unit of the present invention is an electronic circuit unit comprising electronic components mounted on a printed wiring board via a conductive bonding material, wherein the resin binder is cured through the heating step; A core comprising a shape memory material having a transformation start temperature of 200 ° C. or lower and being expanded and deformed at a transformation start temperature or higher, and a melting point including the core having a melting point of 200 ° C.
A configuration in which the electronic component is mounted on the printed wiring board using a conductive bonding material obtained by kneading molten resin particles having the following low melting point metal with the resin binder together with the conductive particles. Have been. According to the electronic circuit unit having the above configuration, when mounting the electronic component on the printed wiring board, the heating and melting of the conductive bonding material in the reflow furnace are performed at 200 ° C. or less, so that the thermal deterioration of the electronic component and the printed wiring Mounting defects due to warpage and the like of the substrate are reduced as much as possible. Further, according to the electronic circuit unit having the above configuration, in the heating step of mounting the electronic component on the printed wiring board, the molten low-melting metal in the molten conductive particles of the conductive bonding material is expanded and deformed by the molten conductive particles. It is spread by the core and comes into contact with a large number of conductive particles existing around the dissolved conductive particles (intermetallic bonding). Thereby, without forming conductive particles from a material having high electrical conductivity such as gold or silver, the electrical conduction performance in the conductive bonding material is improved, and according to the electronic circuit unit according to the present invention, Good electrical continuity between the printed wiring board and the electronic component can be obtained without inconvenience in cost.

[Brief description of the drawings]

FIG. 1 is a conceptual cross-sectional side view showing an embodiment of an electronic circuit unit according to the present invention.

FIG. 2 is a conceptual diagram showing an embodiment of a conductive bonding material according to the present invention.

FIG. 3 is a sectional view showing molten conductive particles in the conductive bonding material shown in FIG. 2;

4 (a) and (b) are external views showing the shape of the core of the molten conductive particles shown in FIG. 3 at normal temperature and the shape at a temperature not lower than the transformation start temperature.

FIG. 5 is a flowchart showing an embodiment of a component mounting method according to the present invention when the electronic circuit unit shown in FIG. 1 is manufactured.

6 (a) to 6 (e) are conceptual diagrams showing steps of manufacturing the electronic circuit unit shown in FIG. 1 in order.

FIG. 7 is a temperature profile showing a mode of maintaining a temperature in a heating step of the component mounting method according to the present invention.

FIGS. 8A and 8B are conceptual diagrams showing states of a conductive bonding material before and after a heating step in a component mounting method according to the present invention.

FIG. 9 is a conceptual diagram showing fused conductive particles in another embodiment of the conductive bonding material according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electronic circuit unit, 2 ... Printed wiring board, 2A ... Electrode, 3, 4 ... Electronic component, 3A, 4A ... Electrode, 10 ... Conductive paste (conductive bonding material), 11 ... Resin binder, 12 ... Conductive particle, 13: fused conductive particles, 13A: core, 13B: low melting point metal, 13 ': fused conductive particles, 13A': core, 13B ': low melting point metal, 13C': flux, S1: conductive bonding material application step, S2 ... Electronic component mounting step, S3 ... Heating step, H1 ... First temperature holding step, H2 ... Second temperature holding step, H3 ... Third temperature holding step.

Claims (3)

[Claims] 1. A conductive bonding material comprising a resin binder cured through a heating step and conductive particles kneaded in the resin binder, wherein the conductive bonding material comprises a shape memory material having a transformation start temperature of 200 ° C. or lower. A core that expands and deforms at or above the transformation start temperature, and a molten conductive particle having a melting point including the core and a low melting point metal having a melting point of 200 ° C. or less, and kneaded with the resin binder together with the conductive particle. Characteristic conductive bonding material. A supply step of supplying a conductive bonding material to the printed wiring board; a mounting step of mounting an electronic component on a predetermined portion of the printed wiring board via the conductive bonding material; Through a heating step of heating the material,
A component mounting method for mounting an electronic component on a printed wiring board via a conductive bonding material, comprising: a resin binder cured through the heating step; and conductive particles kneaded in the resin binder, and starting transformation. Melting the conductive particles comprising a core made of a shape memory material having a temperature of 200 ° C. or lower and expanding and deforming at a temperature equal to or higher than the transformation start temperature, and a low-melting metal having a melting point of 200 ° C. or lower including the core; Using a conductive bonding material kneaded with the resin binder, in the heating step, a temperature holding step at 200 ° C. or less for melting the low melting point metal of the molten conductive particles, A temperature holding step of 200 ° C. or lower for expanding and deforming the core. 3. An electronic circuit unit comprising an electronic component mounted on a printed wiring board via a conductive bonding material, comprising: a resin binder cured through the heating step; and conductive particles kneaded in the resin binder. And a core formed of a shape memory material having a transformation start temperature of 200 ° C. or lower and expanded and deformed at a transformation start temperature or higher, and a low-melting metal containing the core and having a melting point of 200 ° C. or lower. An electronic circuit unit comprising: mounting the electronic component on the printed wiring board using a conductive bonding material obtained by kneading conductive particles together with the conductive particles into the resin binder.