JP4923367B2 - Electrical element mounting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately prevent peel-off at a conductive adhesive material connection part in a mounting structure, in which a capacitor is loaded through a conductive adhesive material on one surface of both lead frames, in a state of crossing over a pair of the lead frames facing each other at a distant. SOLUTION: At first and second lead frames 10 and 20, in an arranging area of a conductive adhesive material 40, a recessed part 50 recessed from one surface 11, 21 in a direction orthogonal to the surface 11, 21 is formed. When applying the conductive adhesive material 40, since the conductive adhesive material 40 enters the recessed part 50 and the conductive adhesive material is adhered closely not only to the surfaces 11 and 21 of the lead frames 10 and 20, but also to a side face of the recessed part 50, the adhered area of the conductive adhesive material and the lead frames is increased.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrical element mounting structure in which an electrical element is mounted on one surface of both lead frames via a conductive adhesive in a state of being crossed across a pair of spaced apart and opposing lead frames.
[0002]
[Prior art]
A general conventional configuration of this type of mounting structure is shown in FIG. As shown in FIG. 14, a pair of plate-like lead frames 10 and 20 made of Cu or the like are spaced apart from each other. A ceramic capacitor 30 as an electrical element is connected and mounted on one surface 11, 21 of both the lead frames 10, 20 by crossing between the two lead frames 10, 20 with a conductive adhesive 40.
[0003]
In such a mounting structure, a conductive adhesive 40 is applied to one surface 11, 21 of the pair of lead frames 10, 20 that are arranged to face each other, and the capacitor 30 is pressed and mounted thereon. It can be formed by heating, cooling and curing 40.
[0004]
[Problems to be solved by the invention]
However, the following problems occur in the conventional mounting structure. There is a difference in thermal expansion coefficient between the electric element 30 and the lead frames 10 and 20. For example, the thermal expansion coefficients of the capacitor 30 made of ceramic and the lead frames 10 and 20 made of Cu are about 10 ppm and 17 ppm, respectively.
[0005]
Therefore, in the process of curing the conductive adhesive 40 and then cooling to room temperature, stress concentrates on the connection part of the conductive adhesive due to the difference in the degree of contraction between the electrical element and the lead frame due to the difference in the thermal expansion coefficient. To do. Then, as shown in FIG. 15, since the conductive adhesive 40 is peeled off from the lead frame 20 or partially peeled off, problems such as an open circuit and an increase in resistance value occur.
[0006]
In addition, as shown in FIG. 16, the lead frames 10 and 20 may be used by being insert-molded in a molding resin 900 serving as a base. In this case, the stress generated by the up and down movements of the lead frames 10 and 20 due to the deformation of the molding resin 900 is concentrated on the connecting portion of the conductive adhesive 40, thereby causing the same peeling as in FIG. May occur.
[0007]
Therefore, in view of the above problems, the present invention mounts an electrical element in which an electrical element is mounted on one surface of both lead frames through a conductive adhesive in a state of being crossed across a pair of spaced apart opposing lead frames. An object of the present invention is to appropriately prevent the occurrence of peeling at the conductive adhesive connecting portion in the structure.
[0008]
[Means for Solving the Problems]
  In order to achieve the above object, according to the first aspect of the present invention, the first lead frame (10) and the second lead frame (20) that are spaced apart from each other and the first and second lead frames are arranged. In an electrical element mounting structure comprising an electrical element (30) mounted on one surface (11, 21) of the first and second lead frames with a conductive adhesive (40) in a state of crossing over
  The conductive adhesive (40) is disposed directly under the electrode (31) of the electric element (30),
  At least one of the first and second lead frames is formed with a recess (50) that is recessed from the one surface in a direction perpendicular to the one surface in the conductive adhesive arrangement region. ) Penetrates the lead frame (10, 20) in a direction perpendicular to the one surface (11, 21),
  The recessed portion (50) is a counterpart in a direction parallel to the one surface (11, 21) from the end surface (12, 22) facing the counterpart lead frame in the lead frame (10, 20) in which the recessed portion is formed. A concave shape that is recessed away from the lead frame on the sideAnd
  The dent shape of the dent (50) is a slit shape extending elongated in a direction away from the mating lead frame,
  The width of the elongated slit shape is ½ or less of the width of the electrode (31) of the electric element (30).It is characterized by that.
[0009]
According to this, when the conductive adhesive (40) is applied, the conductive adhesive enters the recess (50), and not only the one surface (11, 21) of the lead frame (10, 20) but also the side surface ( 51) is also in close contact with the conductive adhesive. Therefore, the adhesion area between the conductive adhesive and the lead frame can be increased, and occurrence of peeling at the conductive adhesive connecting portion can be appropriately prevented.
[0011]
  In the present invention, the recess (50) penetrates the lead frame (10, 20) in a direction perpendicular to the one surface (11, 21).Compared to the case where the recess (50) is recessed in the direction orthogonal to one surface (11, 21) of the lead frame (10, 20), that is, in the middle of the thickness direction of the lead frame, the side surface ( 51) can be increased. Therefore, the adhesion area between the side surface and the conductive adhesive (40) can be increased, which is preferable.
[0012]
By the way, in the structure in which the conductive adhesive is disposed on both sides of both lead frames as in the mounting structure according to the present invention, the distance between the conductive adhesives on both sides of the both lead frames becomes shorter as the distance between the opposing end faces of both lead frames becomes shorter. The distance becomes shorter and short circuit is likely to occur. That is, it is preferable to avoid this short-circuit problem in reducing the size of the structure.
[0013]
  Therefore, in the present invention,Consider this pointAndThe recessed portion (50) is a counterpart in a direction parallel to the one surface (11, 21) from the end surface (12, 22) facing the counterpart lead frame in the lead frame (10, 20) in which the recessed portion is formed. With a recessed shape recessed away from the lead frame on the sideis doing.
[0014]
The recessed portion (50) of the present invention is not only recessed from one surface (11, 21) of the lead frame (10, 20), but also recessed from the opposing end surface (12, 22) facing the counterpart lead frame. Yes. Therefore, the distance between the conductive adhesives of the two lead frames can be increased at the recessed portion of the recessed portion at the facing end surface.
[0015]
  Therefore,BookAccording to the inventionEffectIn addition to the results, even when the facing distance between the first and second lead frames is reduced, it is possible to suppress a short circuit between the conductive adhesives.
[0017]
  In addition, the present inventionThen, since the concave shape of the hollow portion (50) is a slit shape extending in a direction away from the lead frame on the other side,The area of the side surface (51) of the recess (50) can be increased. Therefore, the adhesion area between the side surface and the conductive adhesive (40) can be increased, which is preferable in terms of preventing peeling.
[0018]
  Claims2In the invention described in claimIn the mounting structure of the electric element according to 1,The recess shape of the recess (50) is formed in the vicinity of the portion where the conductive adhesive (40) has the maximum dimension in the direction in which the first and second lead frames (10, 20) are separated. It is characterized by that.
[0019]
  According to this, the adhesion area between the side surface (51) of the recess (50) and the conductive adhesive (40)TheIt can be as large as possible, and the effect of preventing the occurrence of peeling can be suitably exhibited, and the short circuit between the conductive adhesives of both lead frames (10, 20) can be suitably prevented.
[0020]
In addition, the code | symbol in the bracket | parenthesis of each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments shown in the drawings will be described below. Although this embodiment is not limited, a mounting structure using a multilayer ceramic chip capacitor (hereinafter referred to as a capacitor) as an electric element will be described.
[0022]
FIG. 1 is a diagram illustrating a schematic cross-sectional configuration of the electronic device according to the present embodiment. A capacitor 30 and an IC chip 6 are mounted on the lead frames 5, 10, and 20 via a conductive adhesive 40, and the IC chip 6 is connected to the lead frame 5 via a bonding wire 7. . The whole is encased in a mold resin 8 and sealed.
[0023]
In this embodiment, the mounting structure of the capacitor 30 on the lead frames 10 and 20 in FIG. FIG. 2 is a view showing the mounting structure of the capacitor 30. FIG.
[0024]
2A is a side view, and FIG. 2B is a plan view viewed from below in FIG. In both cases, the plate-like first lead frame 10 and the second lead frame 20 are spaced apart from each other. In this example, both lead frames 10 and 20 are obtained by applying electric Ni plating to a Cu plate.
[0025]
A capacitor 30 is mounted on one surface (hereinafter referred to as a mounting surface) 11, 21 of both the lead frames 10, 20 so as to cross between the lead frames 10, 20. The capacitor 30 of this example is a 2012 type multilayer ceramic chip capacitor having a length L: 2.0 mm, a width W: 1.25 mm, and a thickness t: 1.25 mm.
[0026]
Capacitor electrodes 31 are provided at both ends of the capacitor 30 in the length direction (a direction crossing between the lead frames), and the electrodes 31 at each end are conductively bonded to one surface of each of the lead frames 10 and 20, respectively. Electrically and mechanically connected via the agent 40. The conductive adhesive 40 of this example is made of an epoxy resin in which an Ag filler is dispersed.
[0027]
Here, in the lead frames 10 and 20 of the present embodiment, in the arrangement region of the conductive adhesive 40, the direction perpendicular to the mounting surfaces 11 and 21 from the mounting surfaces (one surface) 11 and 21 (that is, the thickness of the lead frame). A depression 50 that is recessed in the direction) is formed. The recess 50 can be formed simultaneously when the lead frames 10 and 20 are formed by pressing or etching.
[0028]
The recessed portion 50 is parallel to the mounting surfaces (one surface) 11, 21 from the opposing end surfaces 12, 22 of the respective lead frames 10, 20 in which the recessed portion 50 is formed, with the opposing lead frames 10, 20. In other words, it has a recessed shape that is recessed so as to be separated from the lead frames 10 and 20 on the other side in the plane direction of the lead frame.
[0029]
That is, the recess 50 is not only recessed in the thickness direction from the mounting surfaces 11 and 21 of the lead frames 10 and 20, but also from the opposite end surfaces 12 and 22 facing the counterpart lead frames 10 and 20 in the planar direction. It is recessed. In this example, the recess 50 penetrates the lead frames 10 and 20 in the thickness direction, and has a slit-like recess shape in the planar direction.
[0030]
FIG. 3 shows a schematic cross-sectional configuration of the connection portion of the conductive adhesive 40 in the vicinity of the recess 50. FIG. 3 corresponds to a part of a cross section taken along the line AA in FIG.
[0031]
As shown in FIG. 3, the conductive adhesive 40 wraps around not only the mounting surface (one surface) 11 of the first lead frame 10 but also the side surface 51 of the recess 50 from the mounting surface 11. It is in close contact. The same applies to the second lead frame 20.
[0032]
As described above, according to the present embodiment, in the arrangement region of the conductive adhesive 40 in the first and second lead frames 10 and 20, the recessed portion 50 that is recessed in the thickness direction from the mounting surfaces 11 and 21 is formed. As a result, the bonding area between the conductive adhesive 40 and the lead frames 10 and 20 can be increased, so that the occurrence of peeling at the conductive adhesive connecting portion can be appropriately prevented.
[0033]
The formation of the recess 50 is based on the results of an experimental study conducted by the present inventors as follows. The mounting structure of this embodiment is based on a mounting method that performs the steps of applying a conductive adhesive to a lead frame, mounting a capacitor, and curing the conductive adhesive, as described in the section of “Prior Art”. Can be formed. The inventors of the present invention implemented this mounting method with the following improvements.
[0034]
FIG. 4 shows a process chart of the mounting method implemented by the present inventors. First, as shown in FIG. 4A, a first lead frame 10 and a second lead frame 20 that are spaced apart from each other are prepared, and the mounting surfaces (one surface) 11, 21 of both the lead frames 10, 20 are prepared. Of these, the conductive adhesive 40 is applied onto the opposing ends of the lead frames 10 and 20 (conductive adhesive application step).
[0035]
Next, as shown in FIG. 4 (b), the capacitor (electric element) 30 is pressed against the applied conductive adhesive 40 to cross the capacitor 30 across the lead frames 10 and 20. In this state, it is mounted on the mounting surfaces 11 and 21 of both lead frames (electric element mounting step).
[0036]
Next, although not shown in the drawings, the lead frames 10 and 20 and the capacitor 30 are electrically and mechanically connected via the conductive adhesive 40 by curing the conductive adhesive 40 (conductive adhesive). Curing step).
[0037]
And in the mounting method which the present inventors implemented, while providing each said process, as shown in FIG.4 (c) in either a conductive adhesive application | coating process or an electrical element mounting process, a conductive adhesive is used. 40 is covered with the corner portion K from the mounting surfaces (one surface) 11, 21 of both the lead frames 10, 20 so as to go around the opposing end surfaces 12, 22.
[0038]
In the conventional general mounting method, as shown in FIG. 4D as a comparative example, in the completed mounting structure, it is normal that the conductive adhesive 40 does not wrap around the opposing end surfaces 12 and 22. .
[0039]
In order to realize the wraparound of the conductive adhesive 40, the application amount of the conductive adhesive 40 is increased as compared with the conventional general mounting method, or the dispensing nozzle 901 shown in FIG. In the case of applying using, a method of narrowing the pitch P between the nozzles 901 can be adopted.
[0040]
Then, the inventors create the structure (wraparound structure) shown in FIG. 4C and the structure of the comparative example shown in FIG. 4D by the mounting method shown in FIG. The occurrence situation of was investigated. An example is shown below.
[0041]
First, the mounting method of the wraparound structure is described. In FIG. 4A, as the lead frames 10 and 20, a plate having a thickness t1 of 0.5 mm obtained by applying Ni plating to a Cu plate was used. Here, the recess 50 is not formed in the lead frames 10 and 20. The distance L1 between the opposed end faces 12, 22 of both lead frames 10, 20 was 0.8 mm.
[0042]
Next, in the conductive adhesive application process, a dispenser nozzle 901 of 22G was used as a needle, and the pitch P between the two nozzles 901 was set to 1.75 mm. Then, the conductive adhesive 40 was applied from each nozzle 901 to the mounting surfaces 11 and 21 of the lead frame.
[0043]
Here, the conductive adhesive 40 to be applied is an epoxy resin in which an Ag filler is dispersed (curing agent: amine, phenol mixed system), and has a viscosity of 48 Pa · s (rotary viscometer, 10 rotational viscosity). The coating amount was 0.75 mg.
[0044]
Next, in the electric element mounting step (see FIG. 4B), the above-described 2012 type multilayer ceramic chip capacitor was used as the capacitor 30. The capacitor 30 was mounted on the mounting surfaces 11 and 21 of the lead frames 10 and 20 by being pressed against the applied conductive adhesive 40 with a mounting load of 1 N.
[0045]
By adopting such a coating amount of the conductive adhesive 40, the pitch P of the dispensing nozzle 901, and the mounting load conditions, the wraparound structure shown in FIG. 4C was obtained. Thereafter, the conductive adhesive 40 was cured at 180 ° C. for 60 minutes in a nitrogen atmosphere.
[0046]
On the other hand, the mounting method of the structure of the comparative example was performed in the same manner as the mounting method of the wraparound structure except that the pitch P of the dispensing nozzle 901 was 2.00 mm, and the structure shown in FIG.
[0047]
A plurality of these wraparound structures and comparative examples were prepared, and the occurrence of peeling was examined. When peeling occurs, the connection resistance increases. Therefore, the connection resistance value is measured between the lead frames 10 and 20 and the electrode 31 of the capacitor 30 by the four-terminal method, and peeling is performed based on the resistance value. We compared ease. The measurement current was 10 mA.
[0048]
FIG. 5 is a diagram showing the results of measuring connection resistance values for the wraparound structure and the comparative example. The connection resistance value between the capacitor electrode 31 and the lead frames 10 and 20 is 0.31Ω on average in the comparative example, whereas it is as low as 0.09Ω on average in the wraparound structure. Further, in the comparative example, some peeling occurred between the lead frames 10 and 20 and the capacitor electrode 31.
[0049]
Therefore, the wraparound structure, that is, the conductive adhesive 40 wrapping from the mounting surfaces (one surface) 11, 21 of the lead frames 10, 20 to the opposing end surface (side surface of the lead frame) prevents the conductive adhesive 40 from peeling off. It can be said that it is effective.
[0050]
This is considered due to the following reasons. The lead frames 10 and 20 and the capacitor 30 are deformed by a cooling cycle in the conductive adhesive curing and an external force applied to the mounting structure itself. The deformation direction is mainly the direction in which the capacitor 30 crosses the lead frame.
[0051]
Therefore, the stress generated in the connection portion of the conductive adhesive 40 is concentrated on the end portion of the conductive adhesive 40 located at the corner K of the lead frames 10 and 20 shown in FIG. Peeling of the adhesive 40 is likely to occur. However, in the wraparound structure shown in FIG. 4C, since the conductive adhesive 40 wraps around the corner K, the stress concentration is reduced, and the conductive adhesive near the stress concentration portion is reduced. It is thought that it is difficult to peel off because the adhesion area of 40 is large.
[0052]
From the results of such experimental studies, it can be said that the mounting method itself that realizes the wraparound structure as described with reference to FIG. 4 is effective in preventing peeling. And in order to implement | achieve a wraparound structure suitably, it is effective to form the hollow part 50 as shown in the said FIG. 2, FIG.
[0053]
That is, by applying the conductive adhesive 40 on the recess 50 or further pressing the capacitor 30, the mounting surfaces 11, 21 of the lead frames 10, 20 are applied to the side surface 51 of the recess 50 intersecting with the mounting surface 11, 21. The conductive adhesive 40 wraps around. In other words, the formation of the recessed portion 50 can easily realize the arrangement configuration of the conductive adhesive 40 similar to the wraparound structure.
[0054]
Further, according to the mounting structure of the present embodiment having the recess 50, the adhesion area between the conductive adhesive 40 and the lead frames 10 and 20 can be increased, and therefore, peeling occurs at the conductive adhesive connecting portion. Can be prevented appropriately.
[0055]
By the way, in the structure in which the conductive adhesive 40 is disposed on both sides of both the lead frames 10 and 20 as in the mounting structure of the present embodiment, the distance between the opposing end surfaces 12 and 22 of both the lead frames 10 and 20 is shortened. Along with this, the distance between the conductive adhesives 40 on both sides is also shortened, and there is a possibility that a short circuit is likely to occur.
[0056]
This problem will be specifically described with reference to FIG. FIG. 6 is a plan view of the process diagram shown in the side view in FIG. 4 (from the lead frame mounting surface).
[0057]
As shown in FIG. 6A, the conductive adhesive 40 applied by the dispensing nozzle spreads in a substantially circular shape on the mounting surfaces (one surface) 11, 21 of the lead frames 10, 20. Next, as shown in FIG. 6B, when the capacitor 30 is pressed onto the conductive adhesive 40, the conductive adhesive 40 is further pressed under the capacitor 30 (shown by a broken line in the figure). It is crushed and spreads.
[0058]
At this time, since there is no escape in the central portion R as compared with the outer peripheral portion of the conductive adhesive 40, the central portion R is more likely to protrude than in the application state. For this reason, the distance between the conductive adhesives 40 on both sides is reduced. In the future, it is assumed that the distance between the lead frames 10 and 20 will be reduced with the miniaturization of the capacitor 30 and the like, but accordingly, a short circuit of the conductive adhesive 40 is likely to occur.
[0059]
In this respect, the present embodiment also has the effect of preventing this short circuit. As shown in FIG. 2, the recess 50 is not only recessed in the thickness direction from the mounting surfaces 11 and 21 of the lead frames 10 and 20 but also mounted from the opposing end surfaces 12 and 22 of the lead frames 10 and 20. In a direction parallel to the surfaces 11 and 21, it has a concave shape that is recessed in a slit shape so as to be separated from the counterpart lead frames 10 and 20.
[0060]
For this reason, when the capacitor 30 is pressed onto the conductive adhesive 40, the recessed portions at the facing end surfaces 12 and 22 in the recessed portion 50 serve as escape places for the conductive adhesive 40, and one part of the conductive adhesive 40. The part enters the inside of the recessed part 50. Then, the amount that the conductive adhesive 40 spreads in the direction of the lead frame on the other side is reduced, and finally the distance between the conductive adhesives 40 of both the lead frames 10 and 20 can be suppressed.
[0061]
As described above, according to the present embodiment, in addition to the above-described effect of preventing peeling, even when the facing distance between the first and second lead frames 10 and 20 is reduced, a short circuit between the conductive adhesives 40 is performed. It becomes possible to suppress.
[0062]
In particular, in the example shown in FIG. 2, the concave shape of the concave portion 50 is the portion where the conductive adhesive 40 has the maximum dimension in the direction in which the first and second lead frames 10 and 20 are separated (that is, this In the example, it is formed in the vicinity of the central portion R) of the conductive adhesive shown in FIG.
[0063]
According to this, since the recessed shape of the recessed portion 50 exists at a portion where the applied conductive adhesive 40 is most spread by the capacitor 30, a short circuit between the conductive adhesives 40 of both the lead frames 10 and 20 is prevented. Can be suitably performed. Moreover, the adhesion area of the side surface 51 of the hollow part 50 and the electroconductive adhesive 40 can be enlarged as much as possible, and the effect of prevention of peeling can also be exhibited suitably.
[0064]
In addition to the shape shown in FIG. 2, the recess 50 of the present embodiment has a mounting surface 11, 21 to a mounting surface 11 in the arrangement region of the conductive adhesive 40 of the lead frames 10, 20. As long as it is recessed in a direction orthogonal to the line 21, the following modifications can be adopted.
[0065]
FIG. 7 shows a first modification of the present embodiment, and is a view seen from the plane direction corresponding to FIG. 2 (b). Whereas the recess shape of the recess portion 50 shown in FIG. 2 is a slit shape, the recess portion 50 of the present example has a recess shape of the recess portion 50 as shown in FIG. It is formed by curving the whole. Also in this example, as described above, the effects of preventing peeling and preventing short circuit are obtained.
[0066]
FIG. 8 is a view showing a second modification of the present embodiment from the plane direction corresponding to FIG. In FIG. 8, the capacitor 30 is omitted. This example is effective when two conductive adhesives 40 are applied to one surface 11, 21 of one lead frame 10, 20 (for example, two dispensing nozzles are used for each lead frame). is there.
[0067]
That is, as shown in FIG. 8, the hollow portion 50 of the second modification is provided with two curved portions for each of the opposed end surfaces 12 and 22. When the conductive adhesive 40 is applied in two places, a protrusion (a portion where the conductive adhesive has the maximum dimension in the direction in which the first and second lead frames are separated) is formed at each central portion. If two concave shapes are provided corresponding to the above, it is effective in preventing a short circuit. In addition, what is necessary is just to provide a dent shape according to the number of application | coating places, when apply | coating a conductive adhesive to three or more places.
[0068]
FIG. 9 is a view showing a lead frame shape as a third modification of the present embodiment from the plane direction corresponding to FIG. 2B, and FIG. 10 is a fourth modification of the present embodiment. It is the figure which showed the lead frame shape as an example from the plane direction corresponded to the said FIG.2 (b). In FIGS. 9 and 10, the capacitor and the conductive adhesive are omitted.
[0069]
In the third modified example shown in FIG. 9, the recessed shape of the recessed portion 50 is a slit shape in FIG. 2 described above, and is formed by curving a part of the opposed end surfaces 12 and 22. In the 4th modification shown in FIG. 10, it forms by the notch shape. These third and fourth modifications also have the effect of preventing peeling and preventing short circuit, as described above.
[0070]
FIG. 11 is a view showing a fourth modification of the present embodiment from the side surface direction corresponding to FIG. 2 has penetrated the lead frames 10 and 20 in a direction orthogonal to the lead frame mounting surfaces 11 and 21 (lead frame thickness direction). As shown, the lead frame is recessed halfway in the thickness direction. Also in this example, as described above, the effects of preventing peeling and preventing short circuit are obtained.
[0071]
FIG. 12 is a view showing a lead frame shape as a sixth modified example of the present embodiment from a plane direction corresponding to FIG. 2B, and a capacitor and a conductive adhesive are omitted. The recessed portion 50 of this example is formed as a through hole formed at a position away from the opposed end surfaces 12 and 22 of the lead frames 10 and 20. In addition, the hollow part 50 of this example may not be a through-hole but the recessed part of the same position.
[0072]
In the sixth modification example, the above-described peeling prevention effect is exhibited, but as is apparent from the drawing, the shape of the opposed end portions 12 and 22 is the same as that of a conventional one, so that the short-circuit prevention effect is hardly exhibited. .
[0073]
Further, when comparing the recessed portion 50 shown in FIG. 2 and each modified example, the recessed portion 50 penetrates the lead frames 10 and 20 in a direction orthogonal to the mounting surfaces (one surface) 11 and 21 (FIG. 2 and FIG. 7 to 10 and 12), the area of the side surface 51 of the recessed portion 50 is maximized as compared with the case where the lead frame is recessed halfway in the thickness direction (FIG. 11). Therefore, the adhesion area of the said side surface 51 and the conductive adhesive 40 can be earned most, and it is preferable.
[0074]
Moreover, when the hollow shape of the hollow part 50 is a slit shape (FIG. 2), compared with the case where the said hollow shape is a curved shape (FIGS. 7-9) and a notch shape (FIG. 10), it is a hollow part. 50 side surfaces 51 can be lengthened, and the area can be increased. Therefore, the adhesion area of the said side surface 51 and the conductive adhesive 40 can be earned, and it is preferable at the point of peeling prevention.
[0075]
The opening area on the mounting surfaces 11 and 12 of the recess 50 is arbitrary as long as the capacitor 30, that is, the mounted electric element does not fall, and the opening shape is also arbitrary.
[0076]
As described above, according to the present embodiment, by providing the recessed portions 50 in the lead frames 10 and 20, the adhesion of the conductive adhesive 40 can be improved, and in some cases, the conductive adhesive can be prevented from being short-circuited. In view of the effect of the recess 50 described above, it is effective to provide the recess 50 only in one of the pair of lead frames 10 and 20.
[0077]
In the above embodiment, the conductive adhesive 40 is applied by the dispensing method, but may be performed by the printing method. In that case, as shown in FIG. 13, the application shape of the conductive adhesive 40 is a shape in which the central portion of the conductive adhesive arrangement region is recessed to prevent a short circuit (see FIGS. 13A and 13B). Or a shape that does not apply to the central portion as a multi-point application (see FIG. 13C).
[0078]
In addition to the capacitor 30, for example, a chip-type element such as a chip resistor may be adopted as the electric element.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic cross-sectional configuration of an electronic device according to an embodiment of the present invention.
2A and 2B are diagrams showing a mounting structure of an electric element according to an embodiment of the present invention, in which FIG. 2A is a side view, and FIG.
FIG. 3 is a partially enlarged cross-sectional view taken along the line AA in FIG.
FIG. 4 is a process explanatory diagram of a mounting method performed by the present inventors.
FIG. 5 is a diagram showing, as a connection resistance value, an effect of preventing peeling of the mounting structure created by the mounting method shown in FIG.
FIG. 6 is an explanatory diagram for explaining a state of a short circuit of the conductive adhesive.
FIG. 7 is a diagram showing a first modification of the embodiment.
FIG. 8 is a diagram showing a second modification of the embodiment.
FIG. 9 is a diagram showing a third modification of the embodiment.
FIG. 10 is a diagram showing a fourth modification of the embodiment.
FIG. 11 is a diagram showing a fifth modification of the embodiment.
FIG. 12 is a diagram showing a sixth modification of the embodiment.
FIG. 13 is a diagram illustrating an example of a shape of a conductive adhesive applied by a printing method.
FIG. 14 is a diagram showing a conventional general mounting structure.
FIG. 15 is a diagram showing a state of peeling of a conventional conductive adhesive.
FIG. 16 is a diagram showing movement of a lead frame due to deformation of a molding resin in which the lead frame is insert-molded.
[Explanation of symbols]
10: First lead frame,
11: One surface (mounting surface) of the first lead frame,
12 ... Opposing end face of the first lead frame, 20 ... Second lead frame,
21: One surface (mounting surface) of the second lead frame,
22 ... opposite end face of the second lead frame, 30 ... capacitor (electrical element),
40 ... conductive adhesive, 50 ... depression.

Claims (2)

A first lead frame (10) and a second lead frame (20) that are spaced apart and opposed to each other;
An electrical element (40) mounted on one surface (11, 21) of the first and second lead frames with a conductive adhesive (40) in a state of crossing between the first and second lead frames. 30) and an electrical element mounting structure comprising:
The conductive adhesive (40) is disposed directly under the electrode (31) of the electric element (30),
At least one of the first and second lead frames is formed with a recess (50) that is recessed from the one surface in a direction orthogonal to the one surface in the conductive adhesive arrangement region.
The recess (50) penetrates the lead frame (10, 20) in a direction perpendicular to the one surface (11, 21),
The indented portion (50) is parallel to the one surface (11, 21) from an end surface (12, 22) of the lead frame (10, 20) in which the indented portion is formed facing the opposite lead frame. It is a concave shape that is recessed away from the counterpart lead frame in a certain direction ,
The recessed shape of the recessed portion (50) is a slit shape extending elongated in a direction away from the counterpart lead frame,
The electrical element mounting structure, wherein the elongated slit-shaped width is ½ or less of the width of the electrode (31) of the electrical element (30) . The recessed shape of the recessed portion (50) is formed in the vicinity of the portion where the conductive adhesive (40) has the maximum dimension in the direction in which the first and second lead frames (10, 20) are separated. The mounting structure for an electric element according to claim 1 , wherein the mounting structure is an electric element.

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