JP2009049308A - Mounting structure of electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure excellent conductivity of a mounting structure of an electronic component constituted by mounting the electronic component having an electrode surface made of Sn-based metal on a substrate and connecting an electrode of the substrate and an electrode of the electronic component to each other through a conductive adhesive. <P>SOLUTION: On an interface between a surface of the electrode 21 of the electronic component 20 and the conductive adhesive 30, the conductive adhesive 30 has a conductive filler 32 exposed on a resin 31 to come into contact with the electrode 21 of the electronic component 20 and when the area rate of the conductive filler 32 exposed per unit area on the interface is defined as a filler exposure rate, the filler exposure rate is ≥4%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic component mounting structure in which an electronic component is mounted on a substrate and the electrode of the substrate and the electrode of the electronic component are connected via a conductive adhesive, and in particular, the electrode of the electronic component is an Sn-based metal. It relates to what consists of electrodes.

  In recent years, in the electronics field due to the increasing awareness of environmental measures, it is urgent to establish a lead-free mounting technology, that is, a technology for mounting electronic components using materials that do not use lead, as a regulatory response to lead (Pb) in solder. ing.

  As lead-free mounting technology, mounting using lead-free solder or conductive adhesive is being studied, but benefits such as stress resistance and lower processing temperature are expected due to the resin connection. There is a growing interest in conductive adhesives. Generally, the conductive adhesive is obtained by dispersing metal particles as a conductive filler in a resin.

  Here, the surface of the electrode of the electronic component to be soldered is generally made of Sn base metal. Specifically, such a Sn-based base metal electrode has a Sn-based metal, that is, Sn such as Sn or SnPb, SnCu, SnAg, SnBi or the like as a main component on a base metal plating layer such as Ni plating ( Plating made of an Sn alloy (containing 50% or more) is applied, and this Sn-based metal plating layer is used as a surface plating layer.

  And mounting such an electronic component, which has been conventionally soldered, on a substrate using a conductive adhesive, supplying a conductive adhesive to the electrode of the substrate, mounting the electronic component, This is done by heat curing. With this process, as the resin shrinks, contact between the conductive fillers in the resin or contact between the conductive filler and the component electrode or the substrate electrode is obtained, and conduction is obtained, and the connection portion is bonded with the resin.

  In the above process, the curing temperature of the resin used for the conductive adhesive is generally about 150 ° C., which is considerably lower than that of a solder that requires a melting temperature of about 230 to 240 ° C. For this reason, as the other members constituting the mounting component and the electronic circuit product, an inexpensive member having low heat resistance can be used, and the product cost can be reduced.

For example, in Patent Document 1, a filler that is easily brought into contact with each other due to resin shrinkage has little translational / rotational motion, and can be used as a substitute for solder by using a conductive adhesive dispersed in a resin having a plurality of reactive groups. It is said that good joint strength and connection resistance, and excellent printability can be obtained.
JP 2000-319622 A

  However, according to the study of the present inventor, when a general-purpose electronic component, that is, an electronic component whose surface of the electrode is made of Sn-based metal, is used, it is possible to ensure good conductivity with a conductive adhesive as a solder substitute. It turned out to be difficult.

  As for the connection characteristics of conventional conductive adhesives, as described in Patent Document 1 and the like, most of them refer to the composition and physical properties of materials, and in particular, the electrodes of electronic components are Sn-based metals. There has been little mention of the connection characteristics of conductive adhesives in some cases.

  The present invention has been made in view of the above problems, and an electronic component whose electrode surface is made of a Sn-based metal is mounted on a substrate, and the electrode of the substrate and the electrode of the electronic component are connected via a conductive adhesive. An object of the present invention is to ensure good electrical conductivity in the electronic component mounting structure.

  In order to achieve the above object, the present inventor has intensively studied. As described above, in the conductive adhesive, since the conductive fillers in the resin are in contact with each other or the conductive filler is in contact with the component electrode and the substrate electrode, conduction is obtained. Attention was paid to the degree of contact between the component electrode and the conductive filler.

  Here, at the interface between the surface of the electrode of the electronic component and the conductive adhesive, the conductive filler is exposed from the resin in the conductive adhesive, and the filler is in contact with the electrode of the electronic component. Therefore, the area ratio of the conductive filler exposed from the resin per unit area at this interface is defined as the filler exposure rate, and when the relationship between the filler exposure rate and conductivity is investigated, the filler exposure rate is equal to or higher than a predetermined value. It has been experimentally confirmed that the conductivity is dramatically improved.

  That is, in the present invention, the conductive adhesive (30) exposes the conductive filler (32) from the resin (31) at the interface between the surface of the electrode (21) of the electronic component and the conductive adhesive (30). When the area ratio of the conductive filler (32) exposed per unit area at the interface is the filler exposure rate, the filler exposure rate is 4 % Or more.

  The present invention has been found experimentally as a result of the study. As shown in FIG. 6 described later, when the filler exposure rate is 4% or more, the electrode (30) via the conductive adhesive (30) is used. 11 and 21) can be drastically reduced, so that good conductivity can be secured.

  Further, the mechanical connection between the electrode (21) of the electronic component and the conductive adhesive (30) is substantially made by the adhesive action of the resin (31) in the conductive adhesive (30), but the filler is exposed. When the rate is too large, the ratio of the resin (31) decreases at the interface between the surface of the electrode (21) of the electronic component and the conductive adhesive (30), and the mechanical connection strength decreases.

  In that respect, if the filler exposure rate is 30% or less, preferably 20% or less, the mechanical connection strength between the electrode (21) of the electronic component and the conductive adhesive (30) can be secured at a practical level ( (See FIG. 6 below).

  Moreover, in order to keep the fluctuation | variation of the electroconductivity with respect to a thermal shock within the range of a practical use level, it is preferable to make a filler exposure rate into 10% or more as FIG. 9 mentioned later shows.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, parts that are the same or equivalent to each other are given the same reference numerals in the drawings for the sake of simplicity.

  FIG. 1 is a diagram showing a schematic cross-sectional configuration of a mounting structure of an electronic component 20 on a substrate 10 according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a detailed configuration of a conductive adhesive 30 in the mounting structure. It is sectional drawing.

  An electronic component 20 is mounted on a circuit board 10 as a substrate, and an electrode 11 of the circuit board 10 and an electrode 21 of the electronic component 20 are electrically connected via a conductive adhesive 30. Hereinafter, the electrode 11 of the circuit board 10 is referred to as a substrate electrode 11, and the electrode 21 of the electronic component 20 is referred to as a component electrode 21.

  The circuit board 10 can employ a ceramic board, a printed board, a lead frame, or the like, and is not particularly limited. The substrate electrode 11 is formed on one surface of the circuit board 10, and is, for example, an Ag-based metal mainly composed of Ag such as Ag, AgSn, and AgPd, or a Cu-based metal mainly composed of Cu such as Cu and CuNi. Or a thick film or plating using a material such as Ni-based metal or Au.

  As the electronic component 20, a surface mount component such as a capacitor, a resistor, or a semiconductor element can be employed. In the example shown in FIG. 1, the electronic component 20 is shown as a chip capacitor.

  The component electrode 21 is a Sn-based base metal electrode. That is, the surface of the component electrode 21 is made of an Sn-based metal containing Sn as a main component. In the example shown in FIG. 2, the component electrode 21 is obtained by forming an Sn-based metal layer 21b on a base metal layer 21a. Here, the base metal layer 21a is formed by applying and curing a thick film conductor paste such as Cu or Ag.

  The Sn-based metal layer 21b, that is, the surface layer of the component electrode 21, is formed by plating Sn-based metal. Here, the Sn-based metal is Sn or made of a Sn alloy containing Sn as a main component (that is, containing 50% or more of Sn) such as SnPb, SnCu, SnAg, SnBi.

  The conductive adhesive 30 includes a resin 31 containing a main agent, a curing agent, a curing accelerator (curing catalyst), a coupling agent, and a diluent, and a conductive filler 32. Specific examples of the resin 31 include a general epoxy resin, and examples of the conductive filler 32 include general materials such as Ag and Cu.

  Further, the conductive filler 32 will be further described. The conductive filler 32 may be a different kind of alloy or a mixture of different kinds of metals. Further, the conductive filler 32 may have a surface coated with fine particles made of a noble metal such as Au.

  As shown in FIG. 2, the conductive adhesive 30 is obtained by dispersing a conductive filler 32 in a resin 31. The conductive fillers 32 in the resin 31 are in contact with each other, and the conductive fillers 32 are in contact with the component electrodes 21 and the substrate electrodes 11. A conductive path is formed by these contacts, and the electrodes 11 and 21 are in contact with each other. Conductivity is obtained. Further, the mechanical connection between the electrodes 11 and 21 is made by adhesion of a resin 31.

  Here, the curing conditions of the conductive adhesive 30 will be described. Since the component electrode 21 of the electronic component 20 is an Sn-based metal, the connection resistance deteriorates when the melting point (231 ° C.) or higher of Sn is raised. In consideration of this, the curing of the conductive adhesive 30 is preferably performed at, for example, about 100 ° C. to 200 ° C., and further, the curing is performed in a nitrogen atmosphere in order to suppress the oxidation of the conductive filler 32.

  Next, a mounting method for realizing the mounting structure of the present embodiment shown in FIG. 1 will be described. First, the conductive adhesive 30 is supplied onto the substrate electrode 11 of the substrate 10 by mask printing or dispensing.

  Next, the electronic component 20 is mounted on the substrate 10 in a state where the substrate electrode 11 and the component electrode 21 are aligned. Then, the conductive adhesive 30 is heated and cured. Thereby, the connection between the electronic component 20 and the substrate 10 is completed, and the mounting structure shown in FIG. 1 is completed.

  In such a mounting structure, as shown in FIG. 2, the conductive adhesive 30 is transferred from the resin 31 to the conductive filler 32 at the interface between the surface of the component electrode 21 of the electronic component 20 and the conductive adhesive 30. Is exposed and is in contact with the component electrode 21.

  Here, the area ratio of the conductive filler 32 exposed from the resin 31 per unit area at the interface between the surface of the component electrode 21 of the electronic component 20 and the conductive adhesive 30 is defined as a filler exposure rate. And in this embodiment, in order to ensure the favorable electroconductivity with the component electrode 21 and the board | substrate electrode 11, this filler exposure rate shall be 4% or more as an original structure.

  The reason for adopting such a unique configuration will be described. The presumed mechanism about the contact form of the component electrode 21 and the conductive filler 32 is as follows. Here, with respect to the conductive adhesive 30 printed on the substrate electrode 11, the state immediately after mounting the electronic component 20 with a low load and a high load, respectively, and further in the case of each of these loads, the conductive adhesive is used. The state after 30 was hardened and an endurance test such as cold heat was performed was considered.

  In the case of low load, the number of the conductive fillers 32 in the resin 31 in the conductive adhesive 30 that are in contact with the component electrode 21 is smaller in the state immediately after mounting than in the case of high load. That is, the filler exposure rate is small.

  Therefore, in a state after the durability test, the conductive filler 32 that contacts the component electrode 21 at the interface between the surface of the component electrode 21 and the conductive adhesive 30 is displaced due to expansion / contraction of the resin 31, and the component electrode 21. It will happen that you will leave. Then, the contact area between the component electrode 21 and the conductive filler 32, that is, the filler exposure rate is reduced, and the connection resistance between the component electrode 21 and the conductive adhesive 30 is increased.

  On the other hand, in the case of a high load, the number of conductive fillers 32 that are in contact with the component electrodes 21 is relatively large in a state immediately after mounting. That is, the filler exposure rate is large. Therefore, even if the number of conductive fillers 32 that contact the component electrode 21 at the interface between the surface of the component electrode 21 and the conductive adhesive 30 decreases after the durability test, The number is sufficiently secured.

  Therefore, in the case of a high load, even in the state after the durability test, the contact area between the component electrode 21 and the conductive filler 32, that is, the filler exposure rate is sufficiently ensured, and the connection between the component electrode 21 and the conductive adhesive 30 is ensured. The resistance does not change substantially. Considering such a mechanism, it is considered necessary to ensure a sufficient contact area in the state immediately after mounting, that is, in the initial state, and attention was paid to the degree of contact between the component electrode 21 and the conductive filler 32.

  The filler exposure rate, which is the area ratio of the conductive filler 32 exposed per unit area at the interface between the surface of the component electrode 21 of the electronic component 20 and the conductive adhesive 30, is used as an index of the contact degree. It was decided to investigate the relationship between exposure rate and conductivity.

  Here, the measuring method of the filler exposure rate was performed as follows. FIG. 3 is a diagram showing the measurement method. First, as shown in FIG. 1, the electronic component 20 and the substrate 10 are connected by the conductive adhesive 30, and then heated at, for example, 230 ° C. to melt Sn on the surface of the component electrode 21. Then, in a state where Sn is melted, the electronic component 20 is pulled and peeled off.

  Then, as shown in FIGS. 3A and 3B, the electronic component 20 is peeled off without the conductive adhesive 30 adhering to the component electrode 21. Therefore, in the surface 30a of the conductive adhesive 30 after the peeling shown in FIG. 3C, the state at the interface between the surface of the component electrode 21 and the conductive adhesive 30 is maintained without substantially changing. ing.

  Therefore, the surface 30a of the conductive adhesive 30 after the peeling is observed with a microscope such as SEM. FIG. 4 is an SEM photograph of the surface 30 a of the conductive adhesive 30. A number of small circular conductive fillers 32 appear relatively white, and the resin 31 located in the gaps appears relatively black. The conductive filler 32 is formed at the interface between the surface of the component electrode 21 and the conductive adhesive 30. It is confirmed that it is exposed.

  The filler exposure rate is obtained at a part of the component electrode 21 that contributes most to conduction, specifically, at a part including the central portion of the component electrode 21. Specifically, the conductive filler 32 and the resin 31 that appear in the black and white state in the SEM photograph of the part are binarized by image processing.

  For example, the area of the conductive filler 32 is obtained by the above image processing in a unit area of about several tens of μm □ on the surface of the conductive adhesive 30 corresponding to the portion including the central portion of the component electrode 21. Then, the area ratio of the conductive filler 32 occupying the unit area is expressed as a percentage as the filler exposure rate, and is obtained.

  The inventor investigated the connection resistance and connection strength as conductivity when the filler exposure rate was changed. FIG. 5 is a diagram showing a procedure for measuring these connection resistances and connection strengths. The electronic component 20 is a general 3216 type capacitor, the substrate electrode 11 is made of an Ag thick film, and the conductive adhesive 30 is the one shown in the above example.

  The connection resistance is an electrical resistance when a current of 10 mA is passed between the component electrode 21 and the substrate electrode 11 via the conductive adhesive 30, and the connection strength is a general tensile strength. FIG. 6 is a graph showing the connection resistance, and the relationship by measurement of the connection resistance and the filler exposure rate.

  In FIG. 6, the horizontal axis represents filler exposure rate (unit:%), the left vertical axis represents connection resistance (unit: mΩ), and the right vertical axis represents connection strength (unit: N). In FIG. 6, the connection resistance graph curve is indicated by a solid line, and the connection strength graph curve is indicated by an alternate long and short dash line.

  As shown in FIG. 6, when the filler exposure rate is slightly smaller than 4%, the connection resistance decreases exponentially, and when the filler exposure rate exceeds 4%, the degree of decrease in the connection resistance is saturated. I will do it.

  Thus, since 4% of the filler exposure rate has a critical significance with respect to electrical conductivity, in the mounting structure of this embodiment, the filler exposure rate is set to 4% or more. Thereby, in this embodiment, the electrical conductivity through the conductive adhesive 30 can be drastically reduced and good electrical conductivity can be ensured.

  As described above, the mechanical connection between the component electrode 21 and the conductive adhesive 30 is substantially made by the adhesive action of the resin 31 in the conductive adhesive 30, but when the filler exposure rate is too large. The ratio of the resin 31 decreases at the interface between the surface of the component electrode 21 and the conductive adhesive 30, and the mechanical connection strength decreases.

  As shown in FIG. 6, the filler exposure rate increases, and the connection strength rapidly decreases around 20% to 30%. From this, it is considered that when the filler exposure rate is 30% or less, preferably 20%, the mechanical connection strength between the component electrode 21 and the conductive adhesive 30 can be secured at a practical level. The same tendency as in FIG. 6 was confirmed also in the electronic component 20 and the substrate electrode 11 in this type of mounting structure other than the above-described investigation example.

  Therefore, in the mounting structure of the present embodiment, the filler exposure rate is 4% or more and 30% or less, preferably 4% in consideration of the electrical connection characteristics and mechanical connection strength through the conductive adhesive 30. More than 20% is preferable.

  Next, a specific method for improving the filler exposure rate will be described. Basically, in order to increase the filler exposure rate to 4% or more, the material and viscosity of the conductive adhesive 30 or the load at the time of mounting can be adjusted according to the size and type of the electronic component 20 or the substrate 10. That's fine. In commercialization, a condition that provides a filler exposure rate of 4% or more is found, and mass production may be performed based on the condition.

  For example, as a guideline for bringing many conductive fillers 32 closer to the interface between the surface of the component electrode 21 and the conductive adhesive 30, (1): increase in curing shrinkage of the resin 31, (2): increase in the resin 31 Various guidelines (1) to (3) such as low viscosity, (3): closest packing of the conductive filler 32, and the like are included.

  Regarding the guide (1), increasing the curing shrinkage force of the resin 31 leads to an increase in the contact pressure of the conductive filler 32. For this purpose, if a highly cross-linked polyfunctional epoxy or the like having a large curing shrinkage force is used as the resin 31, the shrinkage force when the conductive adhesive 30 is cured increases, and the conductive filler 32 is more easily exposed.

  Regarding the guide (2), the viscosity of the resin 31 can be reduced by diluting the resin 31 with a solvent. Examples of such a solvent include butyl carbitol.

  For the guide (3), instead of a general flake-shaped conductive filler 32, a conductive filler 32 having a cubic shape, a spherical shape, or the like is used to increase the packing density, that is, the vertical connectivity, that is, the component electrode The connectivity in the direction from 21 to the substrate electrode 11 can be increased. And any one of these pointers (1) to (3) may be adopted, or all of them may be adopted at the same time.

  Although not directly related to the improvement of the filler exposure rate, the conductive adhesive 30 preferably contains a reducing agent such as aminophenethyl alcohol. According to this, it becomes possible to remove the oxide film formed on the surface of the component electrode 21 by the action of the reducing agent during the application / curing process of the conductive adhesive 30. This is a significant effect for improving the conductivity.

  The above guidelines (1) to (3) are mainly measures from the material side of the conductive adhesive 30, but other measures can also be taken from mounting conditions. That is, in order to bring many conductive fillers 32 closer to the interface between the surface of the component electrode 21 and the conductive adhesive 30 and increase the filler exposure rate, a load that presses the electronic component 20 against the substrate 10 during mounting, that is, mounting Increasing the load can be mentioned.

  FIG. 7 is a graph showing the results of an experimental investigation by the present inventor on the mounting load (unit: N) and filler exposure rate (unit:%) per electronic component. Here, the electronic component 20 and the substrate electrode 11 were the same as those in FIG. 5 described above, and the conductive adhesive 30 had a content of the conductive filler 32 of 88 wt% and the conductive adhesive 30 had a viscosity of 1000 Pa · s.

  As shown in FIG. 7, it was confirmed that the filler exposure rate increases as the mounting load increases. This is in accordance with the above estimation mechanism that the conductive filler 30 is easily exposed to the interface because the conductive adhesive 30 is crushed as the mounting load increases.

  Actually, for some of the samples investigated in FIG. 7, the surface of the conductive adhesive 30 corresponding to the interface between the surface of the component electrode 21 and the conductive adhesive 30 was observed by SEM. In this SEM observation, as in FIG. 3, the electronic component 20 and the substrate 10 were once connected by the conductive adhesive 30 and then peeled off, and the surface of the peeled conductive adhesive 30 was observed.

  FIG. 8 is a SEM photograph showing the results. (A), (b), (c), and (d) are the cases where the mounting loads are 0 N, 0.3 N, 0.5 N, and 3.0 N, respectively. is there. As shown in FIG. 8, as the mounting load increases, more conductive filler 32 is exposed at the interface between the surface of the component electrode 21 and the conductive adhesive 30.

  Actually, the relationship between the mounting load and the filler exposure rate as shown in FIG. 7 is obtained, and by mounting the electronic component 20 on the substrate 10 with the mounting load that achieves the desired filler exposure rate, A mounting structure with a filler exposure rate of 4% or more can be produced. Note that the relationship shown in FIG. 7 is merely a specific example.

  In addition, the inventor conducted a thermal cycle test in consideration of the fact that the electrical conductivity of the conductive adhesive 30 changes due to thermal shock such as a thermal cycle. FIG. 9 is a diagram showing the evaluation results of this cooling / heating cycle test.

  Here, the amount of change in connection resistance before and after the cooling cycle when the filler exposure rate was changed was measured. In the cooling and heating cycle, 250 cycles of −40 ° C. and 125 ° C. were performed. As the connection resistance, the electrical resistance between the component electrode 21 and the substrate electrode 11 through the conductive adhesive 30 was measured in the same manner as in FIG.

  As shown in FIG. 9, as the filler exposure rate increases, the amount of change in connection resistance before and after the cooling / heating cycle decreases. Of course, it is preferable that the amount of change is small, but it is preferably 10 mΩ or less in practical use. If it is 10 mΩ or less, there is substantially no influence on the electrical characteristics.

  Here, in FIG. 9, when the filler exposure rate is 10% or more, the level of change in connection resistance before and after the cooling / heating cycle is 10 mΩ or less. For this reason, in the present embodiment, in order to realize a conduction performance excellent in thermal shock resistance, the filler exposure rate is desirably 10% or more.

(Other embodiments)
Further, as a method for bringing a lot of conductive fillers 32 close to the interface between the surface of the component electrode 21 and the conductive adhesive 30, ultrasonic waves are applied to the substrate 10 before the conductive adhesive 30 is cured. Good.

  Specifically, the mounting process is performed by mounting the substrate 10 on a table that is vibrated by an ultrasonic transducer. Further, if the conductive adhesive 30 is not cured, the electronic component 20 may be mounted while applying ultrasonic waves, or the electronic component 20 may be mounted while applying ultrasonic waves to the substrate 10.

  As the mounting structure, an electronic component whose surface is made of Sn-based metal is mounted on a substrate, and the substrate electrode and the component electrode are connected via a conductive adhesive in which a conductive filler is dispersed in a resin. As long as the conductive filler is exposed from the resin in the conductive adhesive and is in contact with the component electrode at the interface between the surface of the component electrode and the conductive adhesive, The mounting structure shown in FIG.

  For example, in the above-described embodiment, an example in which a chip capacitor is used as an electronic component is illustrated. However, as the electronic component, a surface mount component such as a capacitor, a resistor, a semiconductor element, or the like can be employed.

  Moreover, in the said embodiment, although the electronic component 20 is mounted on the circuit board 10 and the electrode 11 of the circuit board 10 and the electrode 21 of the electronic component 20 are connected via the electroconductive adhesive 30, such as this. After mounting, a packaging process such as attaching a heat sink or filling underfill may be performed.

It is a schematic sectional drawing of the mounting structure of the electronic component which concerns on embodiment of this invention. It is a schematic sectional drawing which shows the detailed structure of the conductive adhesive in the mounting structure of the electronic component shown by FIG. It is a figure which shows the measuring method of a filler exposure rate. It is a microscope picture by SEM of the surface of a conductive adhesive. It is a figure which shows the measuring point of a connection resistance and connection strength. It is a graph which shows the relationship between connection resistance and connection resistance, and a filler exposure rate. It is a graph which shows the relationship between a mounting load and a filler exposure rate. These are SEM micrographs of the surface of the conductive adhesive. (A), (b), (c), and (d) are when the mounting load is 0N, 0.3N, 0.5N, and 3.0N, respectively. It is. It is a figure which shows the evaluation result of a thermal cycle test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 11 ... Board electrode, 20 ... Electronic component, 21 ... Component electrode,
30 ... conductive adhesive, 31 ... resin, 32 ... conductive filler.

Claims (4)

An electronic component (20) is mounted on a substrate (10), and the electrode (11) of the substrate and the electrode (21) of the electronic component are connected via a conductive adhesive (30),
The surface of the electrode (21) of the electronic component is made of Sn-based metal,
In the mounting structure of the electronic component, the conductive adhesive (30) is obtained by dispersing the conductive filler (32) in the resin (31).
At the interface between the surface of the electrode (21) of the electronic component and the conductive adhesive (30), the conductive adhesive (30) exposes the conductive filler (32) from the resin (31). Are in contact with the electrodes (21) of the electronic component,
The electronic component mounting structure according to claim 1, wherein the filler exposure rate is 4% or more, where an area ratio of the conductive filler (32) exposed per unit area at the interface is a filler exposure rate. The electronic component mounting structure according to claim 1, wherein the filler exposure rate is 30% or less. The electronic component mounting structure according to claim 2, wherein the filler exposure rate is 20% or less. The electronic component mounting structure according to any one of claims 1 to 3, wherein the filler exposure rate is 10% or more.

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