JP2005089559A - Method for connecting members using conductive adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for connecting members by using a conductive adhesive which, while maintaining stable electrical contact, hardly allows interfacial separation or cracks to occur and can be used even at a high temperature. <P>SOLUTION: The method for connecting members by using a conductive adhesive, whereby an electronic component 20 is electrically connected to a circuit substrate 10 with a conductive adhesive 30 prepared by compounding a metal filler 31 with a thermosetting resin 32, comprises the following: the first step wherein an electrode 21 of the electronic component 20 is brought into contact with an electrode 11 of the circuit substrate 10 via the conductive adhesive 30; the second step wherein the metal filler 31 contained in the conductive adhesive 30 is melted by heating; and the third step wherein the hardening of the thermosetting resin 32 contained in the conductive adhesive 30 is completed by lowering the temperature to lower than that in the second step. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for connecting members using a conductive adhesive formed by blending a metal filler and a thermosetting resin.

  In general, a conductive adhesive consists of a thermosetting resin such as an epoxy resin mixed with a metal filler as conductive particles such as an Ag filler, and the members are interposed between members. It has a role to be electrically connected (see, for example, Patent Document 1 and Patent Document 2).

  Specifically, such a conductive adhesive is used to electrically connect an electronic component and a circuit board, or to perform an electrical connection between electronic components or an electrical connection between circuit boards. Used for.

  The conductive form in the conductive adhesive is performed in the form of contact between metal fillers (conductive particles).

  Conventionally, the connection method of the member using such a conductive adhesive is such that the first member and the second member are brought into contact with each other via the conductive adhesive, and heated in this state to form the conductive adhesive. It is carried out by curing the thermosetting resin therein.

  When the thermosetting resin is cured and contracted, contact between the metal fillers in the conductive adhesive, contact between the metal filler and the first member, and contact between the metal filler and the second member are obtained. .

  However, the thermosetting resin is electrically insulating, and even if the metal filler is slightly separated, the thermosetting resin enters between the separated metal fillers so that electrical contact can be maintained. Disappear. As a result, there is a problem that the conductivity of the conductive adhesive cannot be improved.

In order to cope with this, a metal having a melting point lower than that normally used for the metal filler is used, and by raising the temperature to the melting point of the low melting point metal or more, the low melting point metal is melted and the metal particles are welded together. Thus, there has been proposed a conductive adhesive that attempts to secure a stable conduction path (see, for example, Patent Document 3 and Patent Document 4).
JP 2000-319622 A JP 2002-265920 A JP 2001-172606 A JP 2001-294844 A

  However, in the case of a conductive adhesive using the above-described low melting point metal as a metal filler, the metal filler that has been welded remelts under a high temperature environment (for example, about 150 ° C.) in the market, and the electrical connection between the metal fillers Contact stability cannot be ensured. That is, there arises a problem that the conductive adhesive cannot withstand use at high temperatures.

  Therefore, in the case of a conductive adhesive using a high melting point metal that can withstand use at high temperatures as a metal filler, the heat treatment is performed to melt the metal filler and complete the curing of the thermosetting resin. Such a connection method can be considered.

  However, in a conductive adhesive using a refractory metal as a metal filler, the following problems arise when trying to melt the metal filler.

  One is a problem of heat resistance of members such as electronic parts to be connected. When heat-treating the conductive adhesive, the member to be connected is also heated together with the conductive adhesive, but in general, electronic components have a limited heat resistance.

  Since electronic components are usually made on the assumption that they are soldered, heat resistance is guaranteed for short-term thermal history required for soldering, for example, heating within 230 minutes at 230 ° C. Yes. On the other hand, the heat resistance for a longer time than that is guaranteed at a lower temperature, for example, about 85 ° C. to 150 ° C. or less.

  Here, in the case of a conductive adhesive using a refractory metal as a metal filler, the heating conditions for realizing melting of the refractory metal and curing of the thermosetting resin exceed the heat resistance limit for a long time in the electronic component. End up.

  For example, when an epoxy resin is used as the thermosetting resin, even if the epoxy resin is cured at a high temperature of about 200 ° C., the time required for the curing is a long time of about 10 to 30 minutes.

  Therefore, if an attempt is made to melt the metal filler using a conductive adhesive using a refractory metal as a metal filler, the electronic component may be deteriorated or damaged depending on the temperature during heat treatment of the conductive adhesive. Problems arise.

  Another problem in the case of a conductive adhesive using a refractory metal as a metal filler is that a large stress is generated when the thermosetting resin is cured.

  As for the curing behavior of the thermosetting resin, the curing is generally completed in an earlier time as the curing temperature is increased. However, when the curing of the thermosetting resin is completed at a high temperature, a large stress due to thermal contraction acts on the thermosetting resin in the process of cooling the thermosetting resin, and peeling occurs at the interface between the member and the thermosetting resin. Or cracks occur in the thermosetting resin.

  As described above, a large stress due to curing is generated in the thermosetting process of the thermosetting resin, after the surface of the member and the thermosetting resin react and adhere to each other, and further curing proceeds, the thermosetting This is because the resin is cured and contracted to generate stress.

  Regarding the problem of large stress generation during curing of the thermosetting resin, in the case of the conductive adhesive using the low melting point metal described above, the melting of the metal occurs sufficiently even at the curing temperature of the resin, It does not appear. However, as described above, the conductive adhesive using the low melting point metal has a problem of remelting in the high temperature environment described above.

  In view of the above problems, an object of the present invention is to realize a conductive adhesive that can be used up to a high temperature while maintaining stable electrical contact and hardly causing interface peeling or cracking. .

  In order to achieve the above object, attention was paid to the fact that the time required for completing the curing of the thermosetting resin is generally longer than the time required for melting the metal filler during heating.

  Then, a metal filler that melts at a heat-resistant guaranteed temperature in the short-term (solder reflow) of the electronic component is used, and heat that maintains fluidity without completing the curing reaction while the metal filler is undergoing welding. After the metal filler was welded using the curable resin, it was considered to complete the curing of the thermosetting resin at a lower temperature and relieve the generated stress.

  In the first aspect of the present invention, the first member (20) and the second member are interposed via the conductive adhesive (30) formed by blending the metal filler (31) and the thermosetting resin (32). In the member connection method using the conductive adhesive for electrically connecting the member (10), the following steps are performed.

  A first step of bringing the first member (20) and the second member (10) into contact with each other via the conductive adhesive (30).

  A second step of heating and melting the metal filler (31) blended in the conductive adhesive (30).

  A third step of completing the curing of the thermosetting resin (32) blended in the conductive adhesive (30) by lowering the temperature than in the second step. These first to third steps are executed in the order of the first step, the second step, and the third step.

  According to this, the metal filler (31) in the conductive adhesive (30) is heated and melted by heating the metal filler (31) blended in the conductive adhesive (30) in the second step. Further, the conduction form between the metal filler (31) and the first member (20), and between the metal filler (31) and the second member (10) is not a simple contact but a joining by welding. Therefore, the electrical contact between them can be made stable.

  Further, after the second step, in the third step, the curing is completed by curing the thermosetting resin (32) at a temperature lower than that in the second step. In other words, this means that in the second step, the heating time is set so that the curing of the thermosetting resin (32) is not completed, and the heating time is shortened.

  Therefore, in the third step, at the interface between the first and second members (10, 20) and the thermosetting resin (32), the thermosetting resin (32) does not adhere and maintains fluidity. In this state, curing shrinkage of the thermosetting resin (32) occurs.

  At this time, since the thermosetting resin (32) flows in the third step, the amount of the curing shrinkage in the thermosetting resin (32) is relaxed. Thereby, the stress generated in the conductive adhesive (30) is reduced, and the occurrence of peeling and cracking at the above-described interface can be suppressed.

  As described above, according to the present invention, it is possible to realize a conduction mode by welding in a metal filler by using a metal filler that is usually used without using a special low-melting-point metal filler as described above. The stress generated when the adhesive (30) is cured can be reduced.

  Therefore, according to the method for connecting members using the conductive adhesive of the present invention, it is possible to realize a conductive adhesive that can be used up to a high temperature while maintaining stable electrical contact and hardly causing interface peeling and cracking. can do.

  In invention of Claim 2, in the connection method of the member using the conductive adhesive of Claim 1, Bi (bismuth), In (indium), Sn (tin), as a metal filler (31), It is characterized by using one selected from Pb (lead), Cu (copper) and alloys thereof.

  The invention according to claim 2 includes, as the metal filler (31), a single product of Bi, In, Sn, Pb, Cu, an alloy of these single products, and an alloy of these single products and other metals other than these single products. It is to use what is selected from the inside. Such a thing can be employ | adopted as a metal filler (31).

  In invention of Claim 3, in the connection method of the member using the electrically conductive adhesive of Claim 1 or Claim 2, as a thermosetting resin (32), the epoxy type which can be hardened at 100 degrees C or less It is characterized by using a resin. Epoxy resins are useful because they have a relatively low cure shrinkage and high adhesion.

  Moreover, in the connection method of the member using the electrically conductive adhesive as described in any one of Claims 1-3 like the invention of Claim 4, the process temperature in a 3rd process is set. The temperature can be 150 ° C. or lower.

  Moreover, in the connection method of the member using the electrically conductive adhesive as described in any one of Claims 1-4 like the invention of Claim 5, the heating temperature in a 2nd process is set. The temperature can be 180 ° C. or higher.

  Moreover, in the connection method of the member using the electrically conductive adhesive as described in any one of Claims 1-5 like the invention of Claim 6, as an electronic component ( 20) and the circuit board (10) can be used as the second member.

  As in the invention described in claim 7, in the method for connecting members using the conductive adhesive described in claim 6, a ceramic substrate (10) can be used as the circuit board.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  This embodiment is a member using a conductive adhesive that electrically connects the first member and the second member via a conductive adhesive formed by blending a metal filler and a thermosetting resin. This connection method will be described on the assumption that an electronic component is used as the first member and a circuit board is used as the second member.

  FIG. 1 is a schematic cross-sectional view showing a mounting structure of an electronic component according to an embodiment of the present invention. 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 electrically connected via the conductive adhesive 30. Hereinafter, the electrode 11 of the circuit board 10 is referred to as the substrate electrode 11, and the electrode 21 of the electronic component 20 is referred to as the component electrode 21.

  The circuit board 10 may be a ceramic board or a printed board, and is not particularly limited. In this example, the circuit board 10 is made of a ceramic board. In this mounting structure, a lead frame may be adopted as the second member.

  In addition, the substrate electrode 11 is formed on one surface of the circuit board 10, for example, Ag-based metal such as Ag (silver), AgSn (silver and tin alloy) and AgPd (silver and palladium alloy), Cu (Copper) and CuNi (copper-nickel alloy) and other Cu-based metals, Ni-based metals, and Au (gold) are used to form thick films and plating.

  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 an example using a chip capacitor.

  Here, the electronic component 20 is assumed to be soldered to a ceramic substrate.

  Therefore, the electronic component 20 is guaranteed heat resistance (short-term heat resistance) against short-term heat history necessary for soldering, for example, heating within 230 minutes at 230 ° C. On the other hand, with respect to heat resistance for a longer time than that, heat resistance (long-term heat resistance) is guaranteed at a lower temperature, for example, about 85 ° C. to 150 ° C. or less.

  The component electrode 21 is made of metal. As the metal constituting the component electrode 21, Au-based metal, Ag-based metal, Ni-based metal, Sn-based metal, and the like are used, but here, Sn-based metal is used as an example, and the surface of the component electrode 21 is used. Is plated with Sn-based metal.

  Here, FIG. 2 is a diagram schematically showing an enlarged vicinity of a connection portion by the conductive adhesive 30 in FIG. The conductive adhesive 30 is formed by blending a metal filler 31 and a thermosetting resin 32.

  The metal filler 31 is dispersed and positioned in the thermosetting resin 32. When the metal filler 31 is melted, between the metal fillers 31, between the metal filler 31 and the substrate electrode 11, and between the metal filler 31 and the component electrode 21, the conventional simple contact is not possible. There is no welding.

  The metal filler 31 is made of a material that melts below the short-term heat-resistant temperature of the electronic component 20 and does not remelt at the maximum temperature at which the electronic component 20 is used.

  As described above, when the electronic component 20 is made on the assumption that it is soldered to the ceramic substrate 10, the metal filler 31 desirably has a melting point in the range of 180 ° C. to 260 ° C. It is preferable.

  This is because, when the melting point of the metal filler 31 is less than 180 ° C., the metal filler 31 is remelted in the most severe conditions (for example, 150 ° C.) normally guaranteed in use of the electronic component 20 or in the metal filler 31. This is because coarsening of the metal crystals is likely to occur.

  On the other hand, when the melting point of the metal filler 31 exceeds 260 ° C., the temperature exceeds the short-term heat resistance (for example, 230 ° C., 1 minute) in the electronic component 20 when the metal filler 31 melts. As a result, the electronic component 20 is deteriorated.

  As such a metal filler 31, for example, Bi (bismuth), In (indium), Sn (tin), Pb (lead), Cu (copper) single item, an alloy of these single items, and these single items A low-melting point metal selected from alloys with other metals other than these single items can be employed.

  Moreover, as the metal filler 31, the low melting point metal as described above may not be used 100%. For example, 80% of the entire metal filler 31 is a non-melting metal filler such as an Ag filler, and the remaining 20% is the low melting point metal, and the low melting point metal melts to connect the Ag fillers. Therefore, the effect can be expected.

  As described above, when a high melting point metal filler such as Ag and a low melting point metal filler are mixed and used, for example, a structure in which powders of respective metals are mixed, or a high melting point metal and a low melting point metal may be used. It is good also as a structure made into an alloy. Furthermore, it is good also as a structure which coated the low melting metal on the surface of the high melting metal.

  Note that the metal filler 31 having a melting point of 180 ° C. to 260 ° C. corresponds to the electronic component 20 to be soldered to the ceramic substrate. For example, when a printed circuit board is used as the circuit substrate 10, The melting point of the metal filler 31 may be lower than 180 ° C., for example.

  Moreover, as the thermosetting resin 32, an epoxy resin, a silicone resin, a polyimide resin, a urethane resin, an acrylic resin, or the like can be employed. These materials are cured at a temperature of about 100 ° C. to 200 ° C.

  In particular, an epoxy resin is useful because it has a relatively small curing shrinkage and a high adhesive force. Moreover, as an epoxy resin, what can be hardened | cured at the temperature of 100 degrees C or less is preferable. And when using an epoxy-type resin, it is necessary to control reaction rate so that it may not harden | cure completely during the heating process at the first high temperature.

  Next, a method for connecting the electronic component 20 and the circuit board 10 using the conductive adhesive 30 in the present embodiment will be described. FIG. 3 is a diagram showing a heating temperature profile (heating profile) in the conductive adhesive curing step of the present connection method.

  Specifically, first, the conductive adhesive 30 is supplied onto the substrate electrode 11 of the circuit board 10 by mask printing or dispensing (conductive adhesive supply step). Next, the electronic component 20 is mounted on the circuit board 10 in a state where the substrate electrode 11 and the component electrode 21 are aligned (component assembly step).

  In this component assembly step, the electronic component 20 (that is, the electrode 21 of the electronic component 20) that is the first member and the circuit board 10 that is the second member (that is, the electrode 11 of the circuit substrate 10) are conductively bonded. This corresponds to the first step of contacting through the agent 30.

  Next, for example, the conductive adhesive 30 is heated and cured at a curing temperature of about 100 ° C. to 200 ° C. (conductive adhesive curing step). Thereby, the connection between the electronic component 20 and the circuit board 10 (that is, the connection between the component electrode 21 and the substrate electrode 11) is completed, and the mounting structure shown in FIG. 1 is completed.

  In this conductive adhesive curing step, the metal filler 31 blended in the conductive adhesive 30 is heated and melted (second step), and then the temperature is lowered than that of the second step. The process is divided into a process (third process) for completing the curing of the thermosetting resin 32 blended in the conductive adhesive 30.

  As an example of the temperature conditions in the second step and the third step, a heating profile as shown in FIG. 3 can be employed. This heating profile can be realized by using a heating furnace capable of controlling the temperature.

  The heating temperature profile shown in FIG. 3 employs a metal filler 31 in the conductive adhesive 30 made of an alloy of 80 wt% Ag and 20 wt% Sn-3Ag-0.5Cu. . Here, Sn-3Ag-0.5Cu is an alloy containing 3% by weight of Ag, 0.5% by weight of Cu, and the remaining Sn. The melting point of the metal filler 31 is 219 ° C.

  In FIG. 3, the thermosetting resin 32 in the conductive adhesive 30 is an epoxy resin that can be cured at 100 ° C. or less. Specifically, the main agent is an epoxy resin, the curing agent is an amine resin, and the catalyst is an amine resin.

  In the heating profile shown in FIG. 3, first, the second step of heating and melting the metal filler 31 blended in the conductive adhesive 30 is performed by raising the temperature from room temperature to 235 ° C.

  The time required for this second step is about 3 minutes. Specifically, while the heating peak temperature in the second step is 235 ° C., a temperature of 220 ° C. or higher is maintained for 45 seconds. Further, a temperature of 80 ° C. or higher is maintained for 80 seconds.

  By this second step, the metal filler 31 blended in the conductive adhesive 30 is melted, and the metal fillers 31 in the conductive adhesive 30, the metal filler 31, the component electrode 21, the metal filler 31, and the like. The conduction form between the substrate electrodes 11 is joining by welding the metal filler 31.

  In the second step, since the heating time is shorter than the time for completing the curing of the thermosetting resin 32, the thermosetting resin 32 is kept in a fluid state.

  Then, the temperature is lowered from the second step, and the third step is executed. Here, the temperature of the third step is 100 ° C., and the required time is about 30 minutes. In this way, in the third step, the curing of the thermosetting resin 32 blended in the conductive adhesive 30 is completed at a temperature lower than the heating temperature in the second step.

  Thus, as shown in FIG. 2, the conductive adhesive 30 is welded between the metal fillers 31, between the metal filler 31 and the substrate electrode 11, and between the metal filler 31 and the component electrode 21. Thus, the electrical connection of the electronic component 20 to the circuit board 10 is completed.

  By the way, according to the present embodiment, the electronic component (first member) 20 and the circuit board (second member) are provided via the conductive adhesive 30 in which the metal filler 31 and the thermosetting resin 32 are blended. ) In the method of connecting the members that electrically connect 10, the first step of bringing the members 10 and 20 into contact with each other via the conductive adhesive 30, and then the conductive adhesive 30 are blended. A second step of heating and melting the metal filler 31, and then a third step of completing the curing of the thermosetting resin 32 blended in the conductive adhesive 30 at a lower temperature than the second step. A method of connecting members using a conductive adhesive is provided.

  According to that, by heating and melting the metal filler 31 blended in the conductive adhesive 30 in the second step, the metal fillers 31 in the conductive adhesive 30, and further, the metal filler 31 and The conduction form between the electronic component 20, the metal filler 31, and the circuit board 10 is not a simple contact but a joining by welding. Therefore, the electrical contact between them can be made stable.

  In addition, after the second step, in the third step, the thermosetting resin 31 is cured at a temperature lower than that in the second step, thereby completing the curing. That is, in the second step, the heating time is set so that the curing of the thermosetting resin 32 is not completed, and the heating time is shortened.

  Therefore, in the third step, the thermosetting resin 32 does not adhere and flows at the interface between the electronic component 20 and the thermosetting resin 32 and at the interface between the electrode 11 of the circuit board 10 and the thermosetting resin 32. In this state, curing shrinkage of the thermosetting resin 32 occurs.

  At the time of this curing shrinkage, since the thermosetting resin 32 flows in the third step, the amount of the curing shrinkage in the thermosetting resin 32 is relaxed. As a result, the stress generated in the conductive adhesive 30 is reduced, and the occurrence of peeling and cracks at the above-described interface can be suppressed.

  As described above, according to the connection method of the present embodiment, it is possible to realize a conduction mode by welding in a metal filler using a metal filler that is normally used without using a special low melting point metal filler, and conducting The stress generated when the adhesive 30 is cured can be reduced.

  Therefore, according to the method for connecting members using the conductive adhesive 30 of the present embodiment, the conductive adhesive that can be used up to high temperatures while maintaining stable electrical contact and hardly causing interface peeling and cracking. 30 can be realized.

  Note that the temperature condition in the heating profile shown in FIG. 3 is merely an example, and of course is not limited to this. For example, the processing temperature in the third step can be changed at a temperature of about 150 ° C. or lower, and the heating temperature in the second step can be changed at a temperature of about 180 ° C. or higher.

  In addition, as described above, the epoxy resin is useful as the thermosetting resin 32 because it has a relatively low degree of cure shrinkage and high adhesive strength. However, when an epoxy resin is used, it is heated at the first high temperature. It is necessary to control the reaction rate of curing so that it does not cure completely during the process.

  This will be further described. In general, in epoxy resins, epoxy resins as the main agent, amine resins and acid anhydride resins as curing agents, phenol resins, amine catalysts such as dicyandiamide as catalysts, phosphorus catalysts such as triphenylphosphine, Those having unpaired electrons in the molecule such as imidazole catalysts are used.

  And the curing reaction of such an epoxy resin proceeds when an epoxy group in the main agent reacts with an amino group, a carbonyl group, a phenol group or the like of the curing agent. In addition, this curing reaction is accelerated by a catalyst added in a smaller amount in the resin.

  This curing reaction proceeds faster at higher temperatures. Therefore, in the second step, within the melting temperature time of the metal filler 31, the thermosetting resin is hardened so that the interface fixation between the thermosetting resin 32 and the members 10 and 20 does not occur. It is necessary to delay the curing of the thermosetting resin 32.

  Specifically, the reaction time can be slowed by adjusting the strength and blending amount of the curing agent and the catalyst so that the thermosetting resin 32 does not sufficiently cure in the second step.

  However, in this method, since the activity of the whole reaction becomes low, it takes a long time until the thermosetting resin 32 is completely cured at a lower temperature in the third step.

  As a method of shortening the time required for the third step, a method is conceivable in which the catalyst is not initially activated and the catalyst is activated by heating in the second step. Specifically, for example, there are the following methods.

  (1) Complex the catalyst. In the first heating (heating in the second step), only the thermal dissociation is caused and the curing reaction is activated here.

  (2) A method of initiating a reaction with an epoxy group by mixing a curing agent and a catalyst as solid small particles and melting and dissolving them in the first heating.

  (3) A method of sealing a catalyst or the like in a microcapsule that is not solid but melts at the initial heating temperature.

  In addition, although the case where an epoxy resin was used as the thermosetting resin 32 was described as an example, the curing time control method was described. However, the curing time can be set in the same way for other resins than the epoxy resin such as a silicone resin. Can be controlled.

  Here, a modified example of the heating process different from FIG. 3 will be described with reference to FIGS. 4, 5, and 6. In the heating process shown in FIG. 3, the processing temperature of the third step is substantially constant during the step.

  On the other hand, in the first modified example shown in FIG. 4, the processing temperature of the third step is assumed to gradually decrease with time.

  In the second modification shown in FIG. 5, the processing temperature of the third step is assumed to increase gradually with time. In the modification shown in FIGS. 4 and 5, the processing temperature of the third step is of course lower than the processing temperature of the second step.

  In the third modification shown in FIG. 6, after the second step is completed, the workpiece is once returned to room temperature, and then the workpiece is placed in a heating temperature environment lower than the processing temperature of the second step. Is.

  It goes without saying that the effects of the present embodiment described above can also be obtained in the first to third modifications. Moreover, the heating process applicable to the connection method of this embodiment is not limited to the said FIGS.

  That is, the heating process in the connection method of the present embodiment includes a second step of heating and melting the metal filler 31 blended in the conductive adhesive 30, and then lowering the temperature compared to the second step. Any heating process that can perform the third step of completing the curing of the thermosetting resin 32 blended in the conductive adhesive 30 can be used as appropriate.

  The connection method in the present embodiment has been described above. In short, the concept of the connection method is to use a metal filler that melts at a heat-resistant guaranteed temperature in a short time (solder reflow) of an electronic component, and the metal filler is Uses a thermosetting resin that does not complete the curing reaction and keeps fluidity while welding is in progress, and then completes the curing of the thermosetting resin at a lower temperature after welding the metal filler. It is intended to relieve stress.

  As a result, it is possible to realize conductivity by welding of metals that can withstand high temperatures and conductive adhesion that has low curing shrinkage stress and hardly causes interface peeling or cracking. In addition, this method clears the heat resistance guaranteed by the electronic component and does not require improvement on the electronic component side, so that it can be easily applied to a conventional production line.

  In the above embodiment, the example in which the present invention is applied to the electrical connection between the electronic component and the circuit board has been described. Of course, the present invention is not limited to this example. You may use in order to perform electrical connection between each other or electrical connection between circuit boards.

  In short, the present invention is applicable as long as it is a connection method for electrically connecting the first member and the second member via a conductive adhesive formed by blending a metal filler and a thermosetting resin. It is possible.

It is a schematic sectional drawing which shows the mounting structure of the electronic component which concerns on embodiment of this invention. It is a figure which expands and shows typically the connection part vicinity by the conductive adhesive in FIG. It is a figure which shows the profile of the heating temperature in the conductive adhesive hardening process of the member connection method in the said embodiment. It is a figure which shows the 1st modification of the profile of the heating temperature in the conductive adhesive hardening process of the member connection method in the said embodiment. It is a figure which shows the 2nd modification of the profile of the heating temperature in the conductive adhesive hardening process of the member connection method in the said embodiment. It is a figure which shows the 3rd modification of the profile of the heating temperature in the conductive adhesive hardening process of the member connection method in the said embodiment.

Explanation of symbols

10: Ceramic substrate as a circuit board,
20 ... Chip capacitor as an electronic component, 30 ... Conductive adhesive,
31 ... Metal filler, 32 ... Thermosetting resin.

Claims (7)

The first member (20) and the second member (10) are electrically connected via a conductive adhesive (30) formed by blending the metal filler (31) and the thermosetting resin (32). In a method for connecting members using a conductive adhesive to be connected,
A first step of contacting the first member (20) and the second member (10) via the conductive adhesive (30);
Subsequently, a second step of heating and melting the metal filler (31) blended in the conductive adhesive (30),
Thereafter, the temperature is lowered than that of the second step, and a third step of completing the curing of the thermosetting resin (32) blended in the conductive adhesive (30) is performed. A method for connecting members using a conductive adhesive. The method for connecting members using a conductive adhesive according to claim 1, wherein the metal filler (31) is selected from Bi, In, Sn, Pb, Cu and alloys thereof. . The method for connecting members using a conductive adhesive according to claim 1 or 2, wherein an epoxy resin curable at 100 ° C or lower is used as the thermosetting resin (32). The method for connecting members using a conductive adhesive according to any one of claims 1 to 3, wherein the treatment temperature in the third step is set to a temperature of 150 ° C or lower. The method for connecting members using a conductive adhesive according to any one of claims 1 to 4, wherein the heating temperature in the second step is 180 ° C or higher. The conductive adhesive according to any one of claims 1 to 5, wherein an electronic component (20) is used as the first member, and a circuit board (10) is used as the second member. The connection method of the used member. The method for connecting members using a conductive adhesive according to claim 6, wherein a ceramic substrate is used as the circuit substrate.

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