JP4566573B2 - Component mounting structure and component mounting method - Google Patents

Description

  The present invention relates to a component mounting structure for mounting a mounting component on various wiring boards, and more particularly to a component mounting structure and a component mounting method for mounting using a conductive adhesive and an insulating adhesive.

  In recent years, lead-free solder is being used in place of conventional lead solder as a method for mounting mounting components such as semiconductor elements and chip components on a wiring board. Furthermore, recently, a mounting method using a conductive adhesive has attracted attention in order to realize an electronic circuit device using an electronic component or a resin substrate having relatively low heat resistance. However, in the mounting using only the conductive adhesive, the mounting area is small and the bonding strength is insufficient. For this reason, the connection resistance value may vary or may change over time.

  In contrast, the electrode terminal of the mounting component and the terminal portion of the wiring board are bonded with a conductive adhesive, and the bonding strength between the surface of the mounting component facing the wiring board between the electrode terminals and the wiring board is high. A method of securing a bonding strength between a mounted component and a wiring board by bonding with a relatively strong insulating adhesive is performed.

  As such a component mounting structure, for example, there is a component mounting method shown in FIGS. 7 and 8 (for example, Patent Document 1). FIG. 7 is a partial cross-sectional view of the main process for explaining this mounting method, and FIG. 8 is a temperature profile when the wiring board on which the mounting components are arranged is heated by a heating device. In this example, as the insulating adhesive, a material having a characteristic that the curing temperature is lower and the curing shrinkage ratio is larger than that of the conductive adhesive is selected and used.

  In the mounting process, first, as shown in FIG. 7A, a wiring board 100 in which terminal portions 200 are formed at predetermined positions of a wiring pattern is prepared. Next, as shown in FIG. 7B, a conductive adhesive 300 is applied on the predetermined terminal portion 200. Further, an insulating adhesive 400 is applied on the wiring board surface 100 between these terminal portions 200. Next, as shown in FIG. 7C, the electrode terminal 510 of the mounting component 500 is opposed to the applied conductive adhesive 300, and the wiring substrate 100 of the mounting component 500 is placed on the insulating adhesive 400. Are positioned and arranged so as to correspond to the facing surface 520 facing each other. This is generally performed by automatically recognizing the position of the terminal portion 200 using a mounter and aligning the mounting component 500 at this position. At this time, the mounting component 500 is temporarily fixed by the adhesiveness between the conductive adhesive 300 and the insulating adhesive 400. Next, the wiring board 100 is placed in a heating furnace with the mounting component 500 temporarily fixed in this manner, and the conductive adhesive 300 and the insulating adhesive 400 are cured. As a result, connection and bonding between the electrode terminal 510 and the terminal portion 200 are performed by the conductive adhesive 300, and bonding between the facing surface 520 of the mounting component 500 and the wiring substrate 100 is performed by the insulating adhesive 400. . The state after this joining is shown in FIG.

When heated in a heating furnace, the temperature T of the conductive adhesive 300 and the insulating adhesive 400 increases with the passage of time t as shown in FIG. In this case, since the curing temperature of the insulating adhesive 400 is lower than the curing temperature of the conductive adhesive 300, when the insulating adhesive 400 reaches the temperature T1, the curing shrinkage occurs first. Thereafter, when the temperature T is further increased to T2, the conductive adhesive 300 starts to cure and shrink. Here, since the curing shrinkage rate of the insulating adhesive 400 is larger than that of the conductive adhesive 300, the conductive adhesive 300 is interposed between the electrode terminal 510 and the terminal portion 200 by the curing shrinkage of the insulating adhesive 400. Curing shrinkage occurs in the compressed state. The connection resistance can be lowered by curing and shrinking in such a compressed state. In addition, since the facing surface 520 of the mounting component 500 is firmly bonded and fixed to the wiring substrate 100 by the insulating adhesive 400, the mounting component 500 is stably stabilized as a whole even if the bonding strength of the conductive adhesive 300 is weak. It has been shown that it can be adhesively fixed.
JP 2001-284780 A

  However, in the above conventional component mounting structure and mounting method, since the curing temperature of the insulating adhesive is set lower than the curing temperature of the conductive adhesive, the insulating adhesive is cured first at the time of heat curing, Thereafter, the conductive adhesive is cured. Thereby, the mounting component and the wiring board are firmly bonded. However, the insulating adhesive is hardened first, and the conductive adhesive is compressed by the shrinkage accompanying this hardening, but the conductive adhesive remains uncured in the compressed state. In this state, when the conductive adhesive is cured, the interval between the mounting component and the wiring board is defined by the cured insulating adhesive, and therefore the conductive adhesive cannot be shrunk during curing. For this reason, insufficient curing shrinkage tends to occur. When such curing shrinkage is insufficient, contact between the conductive fillers in the conductive adhesive is uneven, and the connection resistance value and its variation tend to increase. Further, since the insulating adhesive is formed only on the facing surface of the mounting component and not on the side surface portion, the strength for peeling off the mounting component in the vertical direction is high, but the direction parallel to the wiring board, that is, There was also a problem that the share strength was small.

  The present invention has been made to solve the above-described problems, and when mounting various mounting parts on a wiring board using a conductive adhesive and an insulating adhesive, the bonding strength of the mounting parts to the wiring board can be increased. In addition, an object is to provide a component mounting structure and a component mounting method capable of reducing the connection resistance value and reducing the variation thereof.

  In order to solve the above-described problems, the component mounting structure of the present invention includes a wiring board on which a wiring pattern having a terminal portion is formed on at least a surface, and an electrode terminal that is electrically connected to the terminal portion of the wiring pattern. The mounting component, the electrode terminal of the mounting component, and the terminal portion of the wiring board that are bonded and fixed, and the conductive adhesive that is electrically connected, and the insulating that bonds and fixes the mounting component and the wiring board between the electrode terminals of the mounting component A combination having a curing temperature of the insulating adhesive equal to or higher than the curing temperature of the conductive adhesive or a curing time of the insulating adhesive equal to or higher than the curing time of the conductive adhesive. Made of materials.

  Further, the conductive adhesive and the insulating adhesive include at least one of a curing temperature region of the conductive adhesive, a curing temperature region of the insulating adhesive, a curing time of the conductive adhesive, and a curing time of the insulating adhesive. It is good also as the material of the combination which overlaps.

  By adopting such a configuration, when the conductive adhesive that connects between the electrode terminal of the mounting component and the terminal portion of the wiring board is heated and cured, the compressive force due to the shrinkage of the insulating adhesive is reduced. Hardens while receiving. Even after the conductive adhesive is cured, the insulating adhesive undergoes curing shrinkage, and thus a compressive force is further applied to the conductive adhesive. As a result, the contact portion between the conductive fillers contained in the conductive adhesive increases and the conduction path increases, so the connection resistance value of the conductive adhesive connecting the terminal portion and the electrode terminal and the variation thereof are reduced. Can be small. Further, since the mounted component is firmly bonded to the wiring board with an insulating adhesive, the bonding strength can be increased.

  In the component mounting structure of the present invention, the side fillet may be formed by forming an insulating adhesive on the surface and the side surface of the mounting component facing the wiring board. When forming the side fillet, the coating amount of the insulating adhesive is the sum of the thickness of the conductive adhesive that electrically connects the electrode terminal and the terminal portion and the thickness of the terminal portion of the wiring board, the wiring of the mounting component It is desirable that the amount corresponds to 1.0 to 1.7 times the volume of the space region defined by the width of the surface facing the substrate and the length between the terminal portions.

  By setting it as such a structure, the joint strength of the mounted component with respect to a wiring board can be made larger. In particular, the force in the direction parallel to the wiring board, that is, the shear strength can be increased.

  Further, the component mounting method of the mounting component according to the present invention includes a step of applying a conductive adhesive on the terminal portion of the wiring pattern on the wiring board on which at least the wiring pattern having the terminal portion is formed, and between the terminal portions. The step of applying an insulating adhesive having at least one of the conditions above the curing temperature of the conductive adhesive or the curing time on the wiring board surface of the conductive adhesive and the electrode terminals of the mounting component are in contact with each other. A step of placing the mounting component on the wiring board such that the insulating adhesive and the surface facing the wiring board between the electrode terminals of the mounting component are in contact with each other; and the wiring board on which the mounting component is placed And a step of curing the insulating adhesive subsequent to curing of the conductive adhesive.

  Further, in the above mounting method, the insulating adhesive is at least one of a curing temperature region of the conductive adhesive, a curing temperature region of the insulating adhesive, a curing time of the conductive adhesive, and a curing time of the insulating adhesive. Alternatively, a material having a characteristic of partially overlapping each other may be used.

  According to this method, the electrode terminal of the mounting component is conductively connected to the terminal portion of the wiring pattern on the wiring board with the conductive adhesive, and the mounting component is bonded and fixed to the wiring board with the insulating adhesive. Is done. In addition, when the conductive adhesive connecting the electrode terminals of the mounted component and the terminal portion of the wiring board is cured by heating, the conductive adhesive is cured while receiving a compressive force due to the shrinkage of the insulating adhesive. Even after the conductive adhesive is cured, the insulating adhesive undergoes curing shrinkage, and thus a compressive force is further applied to the conductive adhesive. As a result, the contact portion between the conductive fillers contained in the conductive adhesive increases and the conduction path increases, so the connection resistance value of the conductive adhesive connecting the terminal portion and the electrode terminal and the variation thereof are reduced. Can be small. Further, since the mounted component is firmly bonded to the wiring board with an insulating adhesive, the bonding strength can be increased.

  Furthermore, in the coating process of the insulating adhesive in such a component mounting method, the coating amount of the insulating adhesive is such that the thickness of the conductive adhesive that electrically connects the electrode terminal and the terminal part and the terminal part of the wiring board The amount corresponding to 1.0 to 1.7 times the volume of the space region defined by the thickness of the space, the width of the surface of the mounting component facing the wiring board, and the length between the terminal portions You may make it apply | coat.

  As a result, an appropriate application amount corresponding to the shape of the mounted component can be applied, and the insulating adhesive can be caused to wrap around the side surface portion of the mounted component, so that a side fillet having an optimal shape can be easily formed.

  Further, in such a mounting method, the conductive adhesive and the insulating adhesive are those in which the curing temperature of the conductive adhesive is lower than the curing temperature of the insulating adhesive and the curing time of the conductive adhesive is insulative. A combination of materials that are equal to or less than the curing time of the adhesive, or at least one of the curing temperature region of the conductive adhesive and the curing temperature region of the insulating adhesive, and the curing time of the conductive adhesive and the curing time of the insulating adhesive A material having partially overlapping characteristics may be used. Further, the conductive adhesive and the insulating adhesive may be a combination of materials having the same curing temperature and a longer curing time of the insulating adhesive than that of the conductive adhesive.

  By the mounting method using such a combination of materials, the conductive adhesive can be cured first, and the insulating adhesive can be subsequently cured.

  In the component mounting structure of the present invention, the electrode terminal of the mounting component is conductively connected to the terminal portion of the wiring pattern formed on the wiring substrate with a conductive adhesive, and the mounting component is connected to the wiring substrate with an insulating adhesive. Since it is bonded and fixed, the bonding strength of the mounted component to the wiring board can be increased. Further, since the compressive force accompanying the shrinkage of the insulating adhesive is received when the conductive adhesive is cured, the contact portion between the conductive fillers contained in the conductive adhesive may be increased to increase the conduction path. It is possible to reduce the connection resistance value and the variation of the conductive adhesive connecting the terminal portion and the electrode terminal. As a result, there is a great effect that an electronic circuit device having better characteristics and high reliability can be realized.

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

(Embodiment 1)
FIG. 1 is a partial cross-sectional view of a component mounting structure 10 according to a first embodiment of the present invention. In the component mounting structure 10 according to the present embodiment, the mounting component 5 having the electrode terminals 6 at both ends is insulated from the conductive adhesive 7 on the wiring substrate 1 in which the terminal portion 2 is formed in a part of the wiring pattern. It is configured to be bonded and fixed by the adhesive 8.

  By the way, the wiring board 1 used in this embodiment is a composite base material such as an epoxy resin containing glass fiber, an inorganic material base material such as a ceramic material, or a polyester resin, acrylonitrile butadiene styrene (ABS) resin, polycarbonate resin or polyimide. A base material made of a polymer resin such as a resin, a predetermined wiring pattern formed on the base material, and a terminal portion 2 is formed at a predetermined location of the wiring pattern. In addition, the wiring pattern may be formed inside the base material, or the structure in which the wiring pattern is formed on the surface of the base material is laminated in multiple layers, or the multilayer wiring is formed on the base material surface by the build-up method. It may be the configuration. A wiring pattern is formed at least on the surface of the base material, and the terminal portion 2 only needs to be provided at a predetermined position of the wiring pattern. There is no particular limitation on the multilayer structure or the single-layer structure. .

  The mounting component 5 may be a chip component such as a resistor or a capacitor, or a surface mounting component such as a semiconductor element in which an electrode terminal for connection is formed at the end.

  The conductive adhesive 7 includes a conductive filler, a thermosetting resin, and a curing agent. The conductive filler is fine particles of silver (Ag), nickel (Ni), copper (Cu), or gold (Au), or silver ( Resin beads coated with Ag) are used. The particle size is not particularly limited, and the shape of the fine particles may be spherical, scaly or even irregular. As the thermosetting resin, an epoxy resin, an acrylic resin, or the like is mainly used, but is not particularly limited thereto.

  The insulating adhesive 8 is composed of a thermosetting resin and a curing agent, and an epoxy resin, an acrylic resin, or the like is mainly used in the same manner, but is not particularly limited thereto. However, the insulating adhesive 8 and the conductive adhesive 7 are required to be a combination having certain conditions. That is, it is necessary that the conductive adhesive 7 begins to cure at least first, and the insulating adhesive 8 begins to cure before the conductive adhesive 7 completes the curing. For this purpose, at least one of the conditions that the curing temperature of the insulating adhesive 8 is equal to or higher than the curing temperature of the conductive adhesive 7 or the curing time of the insulating adhesive 8 is equal to or longer than the curing time of the conductive adhesive 7 is satisfied. What is necessary is just to set it as the combination which has the characteristic to satisfy | fill.

  In such a combination, when heated in a heating furnace or the like, the conductive adhesive 7 begins to cure at least first, and the insulating adhesive 8 subsequently cures and shrinks. The adhesive 7 is cured while receiving a compressive force. Accordingly, the compressive force and the curing shrinkage force of the conductive adhesive 7 itself increase the contact portion between the conductive fillers contained in the conductive adhesive 7 and increase the conduction path. As a result, the connection resistance value of the conductive adhesive 7 that connects the terminal portion 2 of the wiring pattern and the electrode terminal 6 of the mounting component 5 and its variation can be further reduced. Further, the bonding strength of the mounting component 5 to the wiring board 1 becomes larger than that of bonding with the conductive adhesive 7 alone, and the reliability of bonding can be improved.

  Next, a manufacturing method for manufacturing the component mounting structure 10 by mounting the mounting component 5 using the conductive adhesive 7 and the insulating adhesive 8 will be described.

  FIG. 2 is a cross-sectional view of main processes for explaining the mounting method of the component mounting structure 10 according to the present embodiment. FIG. 2A is a cross-sectional view of the wiring board 1 in which the terminal portion 2 is formed at a predetermined portion of the wiring pattern. Although only the terminal portion 2 is shown for simplification of the drawing, the wiring board 1 has a surface where the wiring pattern is formed at a predesigned position, the back surface thereof, or the inner layer portion of the base material. Also formed.

  Next, as shown in FIG. 2B, a conductive adhesive 7 is applied onto the terminal portion 2 of the wiring board 1 by, for example, a screen printing method. Thereafter, as shown in FIG. 2C, an insulating adhesive 8 is applied between the two terminal portions 2.

  Next, as shown in FIG. 2 (d), the electrode terminals 6 at both ends of the mounting component 5 are positioned with respect to the applied conductive adhesive 7, and the mounting component 5 is insulatively bonded to the conductive adhesive 7. Place on agent 8. Although this is performed using a mounter, the mounting component 5 is temporarily fixed by the adhesiveness of the conductive adhesive 7 and the insulating adhesive 8.

  Thereafter, the wiring substrate 1 in which the mounting component 5 is temporarily fixed is placed in a heating apparatus such as a tunnel furnace and heated for a predetermined temperature and time to cure the conductive adhesive 7 and the insulating adhesive 8. Let FIG. 3 is a diagram showing a temperature change between the conductive adhesive 7 and the insulating adhesive 8 in the heating device at this time.

  In the manufacturing method of the present embodiment, the conductive adhesive 7 and the insulating adhesive 8 are made of materials whose curing temperature P of the conductive adhesive 7 is lower than the curing temperature Q of the insulating adhesive 8. A case where a chip resistor is used as the mounting component 5 will be described.

  As the conductive adhesive 7 that meets such conditions, for example, a silver (Ag) -based conductive adhesive having characteristics of a curing temperature P = 115 ° C. and a curing time of 10 minutes is used. This conductive adhesive contains 80% by weight of silver (Ag) fine particles as a conductive filler, and the resin component is made of an epoxy resin. Further, as the insulating adhesive 8, for example, an adhesive having a curing temperature Q = 125 ° C. and a curing time of 10 minutes is used. This insulating adhesive contains a viscosity adjusting filler, and the resin component is made of an epoxy resin.

  The wiring board 1 on which the mounting component 5 placed in the heating device is temporarily fixed at the point M shown in FIG. 3 is heated from the surroundings and rises in temperature according to the temperature profile shown in the drawing. When the conductive adhesive 7 is heated to 115 ° C., which is the curing temperature P of the conductive adhesive 7, the conductive adhesive 7 between the terminal portion 2 of the wiring board 1 and the electrode terminals 6 at both ends of the mounting component 5 starts to cure and shrink. . By contracting as the conductive adhesive 7 is cured, the insulating adhesive 8 between the mounting component 5 and the wiring board 1 is slightly compressed, but the insulating adhesive 8 is not yet cured at this point. So it is easily compressed and spreads a little. This state is shown in FIG.

  Further, when the temperature rises and reaches 125 ° C., which is the curing temperature Q of the insulating adhesive 8, the insulating adhesive 8 between the mounted component 5 and the wiring board 1 starts to cure and shrink. At this point, since the curing of the conductive adhesive 7 is not yet completed, the conductive adhesive 7 is cured while receiving a compressive force due to the curing shrinkage of the insulating adhesive 8 until the time R1 when the curing of the conductive adhesive 7 is completed.

  Since the wiring substrate 1 is maintained at the curing temperature Q, the curing shrinkage of the insulating adhesive 8 continues, and the curing shrinkage is completed and completely solidified at time R2 when the curing of the insulating adhesive 8 is completed. Thereafter, when it is gradually cooled and then removed from the heating device, the component mounting structure 10 in which the mounting component 5 is connected and joined by the conductive adhesive 7 and the insulating adhesive 8 is obtained.

  Thus, until the time R1 when the curing of the conductive adhesive 7 is completed, the conductive adhesive 7 is cured while receiving the compressive force of the insulating adhesive 8, and even after the time R1 when the curing is completed is passed. Since the insulating adhesive 8 still cures and shrinks, the conductive adhesive 7 continues to receive a compressive force. By receiving such a compressive force, the conductive fillers in the conductive adhesive 7 can come into close contact with each other, a good conduction path is formed, and the terminal portion 2 and the electrode terminal 6 are connected. The connection resistance value and the variation of the conductive adhesive 7 can be reduced, and the bonding strength of the mounting component 5 can be increased.

  Fifty component mounting structures 10 bonded using the conductive adhesive 7 and the insulating adhesive 8 were produced, and the connection resistance value and the shear strength were measured. As a result, the average value of the connection resistance value per location was 120 mΩ, and the variation (3σ / average value) was 1.8. Moreover, the average value of the shear strength of the chip resistor which is the mounting component 5 was 164 g.

(Embodiment 2)
FIG. 4 is an external perspective view of the component mounting structure 20 according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected about the same element as Embodiment 1 shown in FIG. 1 and FIG.

  In the present embodiment, as in the first embodiment, the chip resistance which is the wiring substrate 1 and the mounting component 5 is used and the conductive adhesive 7 and the insulating adhesive 8 are used for connection and bonding. The difference from the component mounting structure 10 of the first embodiment is that the side fillet 81 is formed such that the insulating adhesive 8 sometimes protrudes to the side surface portion of the mounting component 5. In FIG. 4, a wiring pattern 21 connected to the terminal portion 2 is also shown.

  The application amount and application position when applying the insulating adhesive 8 on the wiring substrate 1 when forming the side fillet 81 will be described with reference to FIG. In FIG. 5A, a conductive adhesive 7 is formed on the two terminal portions 2 of the wiring board 1 by, for example, screen printing, and an insulating adhesive 8 is formed between the terminal portions 2 by, for example, a dispenser. It is a top view which shows the state which carried out. FIG. 5B shows that the mounting component 5 is temporarily fixed on the applied conductive adhesive 7 and the insulating adhesive 8 by a mounting machine, and the conductive adhesive 7 and the insulating adhesive 8. It is a top view which shows the state by which each was expanded. However, in FIG. 5B, the mounting component 5 is removed in order to facilitate explanation of the state where the applied conductive adhesive 7 and the insulating adhesive 8 are spread by the mounting component 5. Yes. For this reason, the mounting component 5 is indicated by a dotted line.

  In the present embodiment, the case where the width of the mounting component 5 and the width of the terminal portion 2 are the same is shown, but the width of the terminal portion 2 and the width of the mounting component 5 are not necessarily the same. Moreover, although the conductive adhesive 7 is formed in a smaller area than the surface area of the terminal portion 2 and the insulating adhesive 8 is formed only between the terminal portions 2, it is not limited to such a formation region and shape. . If the application amount is defined as described later according to the shape of the mounting component 5, the shape and the like can be set as appropriate.

  In FIG. 5B, when the mounting component 5 is placed on the wiring board 1 by the mounter, both the conductive adhesive 7 and the insulating adhesive 8 are subjected to a pressing load by the mounter. 2, it is pushed slightly ahead of the insulating adhesive 8 and partly protrudes from the terminal portion 2 to the wiring substrate 1 in the vicinity of the terminal portion 2. Slightly later, the insulating adhesive 8 is also pushed and spreads to the area of the conductive adhesive 7 that protrudes, and further protrudes to the side surface of the mounting component 5. In this state, when heat-cured, the component mounting structure 20 having the side fillet 81 shown in FIG. 4 is formed.

  Table 1 shows the results of studying the coating amount of the insulating adhesive 8 for forming such a side fillet 81.

  In Table 1, the coating amount W of the insulating adhesive 8 is standardized based on the volume V described below. That is, the volume V is defined by the thickness of the wiring board 1 including the terminal portion 2 and the conductive adhesive 7, the width of the mounting component 5, and the distance between the terminal portions 2. In addition, since it is common that the conductive adhesive 7 has an unevenness | corrugation partially, let the thickness be an average thickness. In addition, the distance between the terminal portions 2 may be a value that takes into account the length of the portion where the conductive adhesive 7 protrudes. The amount of protrusion is almost determined by the pressing load when the mounting component 5 is mounted by the mounter and the coating amount of the conductive adhesive 7, and can be set in advance.

  The observation results of the coating amount W of the insulating adhesive 8 and the formation state of the side fillet 81 based on the volume V are shown in Table 1, and the range of W / V = 1.0 to 1.7 is shown. It was found that a good side fillet was formed. That is, when W / V = 0.9 or less, the insulating adhesive wraps around the side surface portion and a sufficient side fillet is not formed. Further, when W / V = 1.8 or more, the insulating adhesive 8 spreads and mixes to the side portion of the conductive adhesive 7, so that the connection resistance and the bonding strength become unstable. On the other hand, when the coating amount is in the range of W / V = 1.0 to 1.7, a good side fillet is formed, and the mixing of the conductive adhesive 7 and the insulating adhesive 8 is also caused by connection resistance and bonding. It occurs only to the extent that it does not affect the strength. As a result, it has been found that the connection resistance can be reduced and the bonding strength can be increased.

  As a result of obtaining the connection resistance value and the shear strength for the component mounting structure 20 having such a side fillet 81, the connection resistance value is almost the same as that of the component mounting structure 10 of the first embodiment, and the connection resistance value per place. The average value was 120 mΩ, and the variation (3σ / average value) was 1.8. Moreover, the average value of the shear strength of the chip resistor which is the mounted component 5 was 215 g, and it was confirmed that the shear strength can be increased by providing the side fillet 81.

  Next, for comparison with the component mounting structure 10 of the first embodiment and the component mounting structure 20 of the second embodiment, the insulating property is lower in curing temperature and shorter in curing time than the conductive adhesive. A component mounting structure using an adhesive was prepared. That is, as the conductive adhesive, a silver (Ag) -based conductive adhesive having a curing temperature of 115 ° C. and a curing time of 10 minutes is used. This conductive adhesive contains 80% by weight of silver (Ag) fine particles as a conductive filler, and the resin component is made of an epoxy resin. This conductive adhesive is the same as that used in the first and second embodiments, and AgP80 (manufactured by Ajinomoto Fine Techno Co., Ltd.) was used. Further, an insulating adhesive having a curing temperature of 80 ° C. and a curing time of 1 minute is used. As this insulating adhesive, MR-8121K (manufactured by Panasonic Factory Solutions) containing a viscosity adjusting filler and having a resin component made of an epoxy resin was used.

  In the same manner as in the first and second embodiments, a chip resistor was mounted as a mounting component on the wiring board under the same conditions. In the comparative component mounting structure manufactured in this way, the average value of the connection resistance value is 320 mΩ per location with and without the side fillet, and the variation (3σ / average value) is 2 .1. In addition, in the case of this comparative component mounting structure, the shear strength of the chip resistance is 160 g on average in the configuration without the side fillet, and the condition of W / V = 1.0 in the configuration with the side fillet. It was 205g.

  The results of the first embodiment and the second embodiment and the results of the comparative component mounting structure are shown together in Table 2.

  Thereby, it was confirmed that the component mounting structures 10 and 20 according to the embodiment of the present invention have lower connection resistance values and smaller variations than the comparative component mounting structures. Furthermore, in the case of the component mounting structure 20 of the second embodiment, it was also confirmed that the shear strength was greatly improved due to the effect of the side fillet.

  In the component mounting structure 10 according to the first embodiment and the component mounting structure 20 according to the second embodiment, a combination of materials in which the curing temperature of the conductive adhesive is lower than the curing temperature of the insulating adhesive is used. However, the present invention is not limited to this. For example, the curing temperature of the conductive adhesive and the curing temperature of the insulating adhesive may be the same, but a combination of materials in which the curing time of the insulating adhesive is longer than the curing time of the conductive adhesive may be used. Using such a material, it may be manufactured by the same manufacturing method as the component mounting structure 10 of the first embodiment or the component mounting structure 20 of the second embodiment. FIG. 6 shows a temperature profile when the wiring board on which the mounting component temporarily fixed using this combination of materials is arranged is heated in the heating device.

  That is, the wiring board put into the heating device at the point N shown in FIG. 6 has a temperature equal to the curing temperature R of the conductive adhesive and the curing temperature S of the insulating adhesive. When the curing temperature is heated to R and S, the conductive adhesive between the terminal portion of the wiring board and the electrode terminal of the mounted component and the insulating adhesive between the terminal portions start to cure and shrink almost simultaneously. . For this reason, the conductive adhesive itself undergoes curing shrinkage and at the same time receives a compressive force due to the curing shrinkage of the insulating adhesive. For this reason, the conductive fillers come into close contact with each other, the conductive path is improved, and the connection resistance can be reduced. The conductive adhesive is cured while receiving the compressive force due to the curing shrinkage of the insulating adhesive until the time R3 when the curing is completed. At this time R3, the insulating adhesive is still in the course of curing, and thereafter Curing shrinkage continues until time R4. Therefore, since the conductive adhesive is subsequently subjected to the compressive force of the insulating adhesive, the conductive path is further improved.

  When the curing of the insulating adhesive is completed, the wiring substrate is gradually cooled and then taken out of the heating device to complete the manufacturing process.

  As described above, the conductive adhesive and the insulating adhesive have the same curing temperature. However, if the insulating adhesive is longer in curing time, the conductive adhesive is insulated. Since the curing shrinkage occurs while receiving the compressive force of the adhesive, the conductive path is improved, and the connection resistance value and its variation can be reduced.

  Moreover, it is good also as a manufacturing method which forms a side fillet in the side part of a mounting component similarly to the component mounting structure 20 of Embodiment 2. FIG.

  In consideration of the general characteristics of adhesives including conductive adhesives and insulating adhesives, temperature variations of heating devices, etc., the curing time of insulating adhesives with respect to the curing time of conductive adhesives is It is desirable to use a combination of materials longer than 5 minutes. Further, it is desirable that the heating device can stably maintain the curing temperature of the insulating adhesive for at least the time when the curing of the insulating adhesive is completed.

  In the component mounting structure 10 of the first embodiment and the component mounting structure 20 of the second embodiment, the chip resistor has been described as an example of the mounted component, but the present invention is not limited to this. That is, the same effect can be obtained even with a chip component or a multiple chip component having three or more electrode terminals, or a mounting component such as a semiconductor element having an electrode terminal at an end.

  In the component mounting structure and the mounting method of the present invention, since the mounting component is mounted on the wiring board using the conductive adhesive and the insulating adhesive, the connection resistance value and its variation are small, and the bonding strength can be increased. A highly reliable component mounting structure can be obtained. Therefore, the present invention is useful in the field of electronic circuit devices in which various mounting components are mounted on a wiring board, particularly electronic circuit devices that use a wiring board having relatively low heat resistance.

The fragmentary sectional view of the component mounting structure concerning Embodiment 1 of this invention Sectional drawing of the main process explaining the component mounting method of the component mounting structure concerning the embodiment The figure which shows the temperature change of the conductive adhesive and insulating adhesive in a heating apparatus in the component mounting method of the component mounting structure concerning the embodiment External appearance perspective view of the component mounting structure concerning Embodiment 2 of this invention. The figure for demonstrating the application quantity and application position when apply | coating an insulating adhesive agent on a wiring board with the component mounting structure concerning the embodiment In the modification of the mounting method of the component mounting structure according to the first embodiment and the second embodiment of the present invention, the curing temperature of the conductive adhesive and the insulating adhesive is the same, but the curing time is the insulating bonding The figure which shows the temperature profile when heating the wiring board in the case of a combination of materials with longer agents Partial sectional view of the main process to explain the conventional component mounting structure and mounting method The figure which shows the temperature profile when a wiring board is heated with a heating device in the same component mounting structure and mounting method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 Wiring board 2,200 Terminal part 5,500 Mounting component 6,510 Electrode terminal 7,300 Conductive adhesive 8,400 Insulating adhesive 10,20 Component mounting structure 21 Wiring pattern 81 Side fillet 520 Opposite surface

Claims (4)

A wiring board having a wiring pattern having terminal portions formed at least on the surface;
A mounting component having an electrode terminal electrically connected to the terminal portion of the wiring pattern;
A conductive adhesive that bonds and fixes the electrode terminal of the mounting component and the terminal portion of the wiring board, respectively,
An insulating adhesive that bonds and fixes the mounting component and the wiring board between the electrode terminals of the mounting component;
The curing temperature of the insulating adhesive and the curing temperature of the conductive adhesive are the same, the curing time of the insulating adhesive is equal to or longer than the curing time of the conductive adhesive, and at the same time, a material that starts curing shrinkage. Component mounting structure characterized by combination. The component mounting structure according to claim 1, wherein the difference in the pre-curing time is 5 minutes or more. Applying a conductive adhesive on the terminal portion of the wiring pattern of the wiring board having a wiring pattern having a terminal portion formed at least on the surface;
On the wiring board surface between the terminal portion, a step of applying the insulation adhesive,
Wiring the mounting component so that the conductive adhesive contacts the electrode terminal of the mounting component, and the insulating adhesive contacts the surface of the mounting component between the electrode terminals facing the wiring substrate. Placing on the substrate;
Curing the conductive adhesive and the insulating adhesive by heating and holding the wiring board on which the mounting component is disposed up to the curing temperature of the conductive adhesive and the insulating adhesive; and in part article mounting how to include a,
The conductive adhesive and the insulating adhesive are a combination of materials having the same curing temperature and a long curing time of the insulating adhesive as compared to the conductive adhesive and simultaneously starting curing shrinkage. A component mounting method characterized by being used. The component mounting method according to claim 3, wherein the difference in curing time is 5 minutes or more.

Images