TW201519385A - Joint structure and semiconductor device using it - Google Patents

Abstract

Disclosed is a bonding structure, which uses nano structures, and which is capable of greatly improving strength of a bonding layer and a member interface at the time of bonding a plurality of members. In the present invention, on the surfaces of a plurality of members to be bonded, such as a lead frame and a heat dissipating base of a semiconductor device, spring layers configured from spring-shaped nanostructures having dimensions in a nano order scale (less than 1 [mu]m) are provided, respectively, and the members to be bonded are bonded to each other by having the spring layers fitted in each other.

Description

Bonding structure and use of the semiconductor device thereof

The present invention relates to a bonding structure and a semiconductor device using the bonding structure.

In order to join a plurality of members, various bonding techniques such as soldering or an adhesive have been conventionally applied. In the above-described bonding technique, as described in Patent Document 1 and Patent Document 2, a plurality of structures having a spiral shape or the like are provided on the joint surface of the member, and the structures are in contact with each other or the structure. The technique of joining a body to other structures to join a plurality of members is also known.

The technique described in Patent Document 1 is that a spiral contact conductor having a length of 5 mm is provided on a surface of a copper thin plate having a width of 20 mm and a length of 50 mm, and the copper thin plates are joined to each other by winding such contact conductors.

In the technique described in Patent Document 2, a conductive elastic body in which a buffer material is randomly disposed inside a pressure-sensitive adhesive is provided on a circuit-mounted substrate on which a semiconductor element is mounted, and the buffer material is formed into an Au or Al wire having a diameter of 20 to 50 μm. A spiral structure or a lattice structure. By guiding here The electric body elastic body is inserted into a metal bump provided on the semiconductor element to bond the semiconductor element and the circuit mounting substrate.

According to the technique described in Patent Document 1 or Patent Document 2 as described above, the reliability of electrical or mechanical or thermal connection is improved.

[Advanced technical literature]

[Patent Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2003-299506 (paragraphs 0016 and 0020, Fig. 3)

[Patent Document 2] Japanese Laid-Open Patent Publication No. 2006-287091 (paragraphs 0036 and 0040, Figs. 1 and 2)

When the load or displacement acts on the joint structure for joining the different members, the breakage of the joint portion disposed between the members to be joined prevents the interface from being peeled off between the joint member and the joint portion. Therefore, a joint structure in which the joint itself or the interface is strong is desired.

In particular, in a power semiconductor device or the like, in a device in which members formed of different materials are used in combination, thermal stress is inevitably generated. Further, as the device is miniaturized or densified, thermal stress increases, and there is a tendency in the future. Therefore, in such a device, the above problems are more Significant.

In this regard, the aforementioned prior art is difficult to greatly increase the strength of the joint layer or the interface of the member.

Accordingly, the present invention provides a bonding structure capable of greatly increasing the strength of a bonding layer or a member interface when a plurality of members are joined, and a semiconductor device using the bonding structure.

In order to solve the above-described problems, in the joint structure of the present invention, a spring-like nanostructure having a size of a size of less than 1 μm, that is, a nanometer scale, is provided at a joint portion between the members to be joined.

According to one aspect of the present invention, the first member, the second member, and the joint structure of the joint portion of the first member and the second member are joined, and in the joint structure, the joint portion has a plurality of spring-shaped nai Rice structure.

Further, the first and second members may be any of a conductor, a semiconductor, and an insulator. Further, the spring-like nanostructure is an insulating material such as a conductive material such as a metal material or a ceramic material. Further, the spring shape may be, for example, a spiral shape, that is, a coil shape, or a shape having a plurality of linear portions or a polygonal line shape in which a plurality of linear portions are connected to each other.

Further, the above-described bonding structure of the present invention is applicable to bonding of a lead frame of a semiconductor device to a heat radiation substrate or bonding of a lead frame and a sealing resin.

According to the present invention, since the nanostructure itself is stronger than the block material and a very large number of nanostructures can be disposed on the joint surface, the mechanical strength of the joint portion and the interface between the member and the joint portion are mechanical. Sexual strength will increase significantly. By this, the reliability of the joint is greatly improved.

The configuration and effects of the problems other than the above are known from the following description of the embodiments.

1‧‧‧Semiconductor components

2‧‧‧Solder

3‧‧‧ lead frame

4‧‧‧Insulation

4a, 4b, 4d‧‧‧ spring layer

4c‧‧‧Resin

5‧‧‧Exothermic substrate

21‧‧‧Connected components

22‧‧‧ surface layer

23‧‧‧Evaporation of atoms

24‧‧‧Spring layer

31‧‧‧Connected components

32‧‧‧Spring layer

33‧‧‧Resin

121‧‧‧ Sealing resin

Fig. 1 is a schematic cross-sectional view showing a semiconductor device of a first embodiment.

Fig. 2(a) shows the failure mode of the joint portion.

Fig. 2(b) is a broken mode showing the joint portion.

Fig. 2(c) is a broken mode showing the joint portion.

Fig. 3 (a) is a view showing a method of manufacturing the joint structure of the first embodiment.

Fig. 3 (b) is a view showing a method of manufacturing the joint structure of the first embodiment.

Fig. 3 (c) is a view showing a method of manufacturing the joint structure of the first embodiment.

Fig. 4 (a) is a view showing a method of manufacturing the joint structure of the first embodiment.

Fig. 4 (b) is a view showing a method of manufacturing the joint structure of the first embodiment.

Fig. 4 (c) is a view showing a method of manufacturing the joint structure of the first embodiment.

Figure 5 is a top photograph and a cross-sectional photograph of the spring layer.

Fig. 6 is a schematic view of an indentation test device for a spring layer.

Fig. 7(a) shows the measurement results of the indentation test.

Fig. 7(b) shows the measurement results of the indentation test.

Fig. 7(c) shows the measurement results of the indentation test.

Fig. 8 is a schematic cross-sectional view showing a joint structure of a second embodiment.

Fig. 9 is a view showing the nature of the joint structure.

Fig. 10 is a schematic cross-sectional view showing a joint structure of a third embodiment.

Fig. 11 is a cross-sectional photograph of a spring layer having a multi-linear shape.

Fig. 12 (a) is a view showing a method of manufacturing the joint structure of the fourth embodiment.

Fig. 12 (b) is a view showing a method of manufacturing the joined structure of the fourth embodiment.

Fig. 12 (c) is a view showing a method of manufacturing the joined structure of the fourth embodiment.

Fig. 13 is a simulation result showing a deformation behavior of a spring having a two-linear shape.

Fig. 14 is a simulation result showing a deformation behavior of a spring having a three-linear shape.

Fig. 15 (a) is a schematic cross-sectional view showing a joint structure of a fifth embodiment.

Fig. 15 (b) is a schematic cross-sectional view showing a joint structure of a fifth embodiment.

Fig. 15 (c) is a schematic cross-sectional view showing a joint structure of a fifth embodiment.

Fig. 16 is a schematic cross-sectional view showing a joint structure of a sixth embodiment.

Fig. 17 is a schematic cross-sectional view showing a joint structure of a seventh embodiment.

Figure 18 is a cross-sectional schematic view showing a semiconductor device of an eighth embodiment.

Hereinafter, embodiments of the present invention will be described using the drawings.

[Example 1]

Fig. 1 is a schematic cross-sectional view showing a semiconductor device according to a first embodiment of the present invention.

In the present embodiment, the semiconductor element 1 is bonded to the lead frame 3 made of a metal material via the solder 2, and the lead frame 3 and the heat releasing substrate 5 composed of a metal material are passed through the joint portion including the insulating layer 4. Engage. In addition to these members, a wiring for electrically connecting the terminal provided on the semiconductor element 1 to the lead frame or a sealing material for sealing the entire semiconductor device is also provided for electrically connecting the electrodes of the semiconductor device and the external circuit. Terminals, etc., are omitted in Figure 1.

In the present embodiment, an IGBT (Insulated Gate Bipolar Transistor) formed of a germanium wafer having a thickness of about 10 mm and a thickness of about 0.1 mm is used as the semiconductor element 1. Further, IGBT is well known as a representative power semiconductor device.

In the lead frame 3, the thermal resistance and the electric resistance are reduced by using copper having a thickness of about 0.5 mm, and the exothermic substrate 5 is made lightweight while ensuring heat dissipation under the use of aluminum. At this time, in the insulating layer 4, the spring layer 4a provided on the surface of the lead frame 3 and the spring layer 4b provided on the surface of the heat radiation substrate 5 are mechanically intertwined and fitted, and also include the wires between the spring layers. A space between the frame 3 and the heat releasing substrate 5 is filled with a resin 4c as a filling member.

Among the spring layers 4a, 4b, a nanostructure having a spring shape (hereinafter referred to as a spring) is plural or a plurality of arrays. Further, in the present embodiment, a coil-like spring is arranged. Here, the nanostructure is a structure having a geometric dimension of a nanometer scale smaller than 1 μm.

This embodiment is made of tantalum nitride, that is, ceramic bullets. The spring layer 4a provided on the surface of the lead frame 3 and the spring layer 4b provided on the surface of the heat radiation substrate 5 are spring-made, and the electric power between the lead frame 3 and the heat radiation substrate 5 is ensured under the resin 4c using an epoxy resin. Insulation. Further, the thickness of the insulating layer 4 is set to 10 to 100 μm in accordance with the required insulating properties. In the spring layers 4a, 4b, the coil-like springs are closely arranged. The shape of each spring is about 40 nm, the outer diameter of the coil is about 120 nm, and the coil pitch is about 150 nm. The more away from the lead frame 3 or the heat releasing substrate 5, the more the wire diameter or the outer diameter of the coil is. Become bigger.

In the present embodiment, since copper is used for the lead frame 3 and aluminum is used for the heat release substrate 5, the insulating layer 4 is a material having a different joint expansion coefficient. Therefore, once the temperature of the semiconductor device changes due to the heat generation of the semiconductor element 1 or the change in the temperature of the use environment, the thermal deformation of the lead frame 3 and the heat radiation substrate 5 is poor, but the difference in deformation is absorbed by the insulating layer 4. . In the present embodiment, the insulating layer 4 is composed of the resin 4c and the spring layers 4a, 4b formed of the low-elastic nanostructure. Therefore, the insulating layer 4 is reduced in elastic modulus and can be reliably absorbed and deformed.

In the present embodiment, since the material of the nanostructure of the spring layers 4a, 4b is tantalum nitride having high insulation, even the spring layer 4a provided on the surface of the lead frame 3 and the spring layer provided on the surface of the heat release substrate 4b is contacted or abutted by fitting, and the electrical insulation of the lead frame 3 from the heat releasing substrate 5 can be ensured.

Fig. 2 is a view showing a typical failure mode of the joint portion.

Fig. 2(a) is a mode in which the interface of the joined portion is peeled off, and Fig. 2(b) It is a mode in which the crack progresses inside the bonding layer, and FIG. 2(c) is a mode in which the interface between the spring and the filling resin is peeled off.

In the present embodiment, the coil pitch is about 150 nm, so that the springs per unit area (1 mm ² ) respectively disposed on the surface of the lead frame 3 or the surface of the heat release substrate 5 are about 4 × 10 ⁷ , and the wire diameter is about 40 nm. Therefore, the area of the spring per unit area (1 mm ² ) of the interface is π × (20 × 10 ^-6 ) ² × 4 × 10 ⁷ = 0.05 mm ² , that is, 5% of the total area. Generally, the strength of the tantalum nitride block is about 700 MPa or more. Further, since the material of the spring constituting the nanospring layer is a nanometer-scale structure, it is difficult to cause indexing inside the crystal, and the stress or strength of the relief is twice or more larger than that of the bulk material as a result of the test described later. Therefore, when the strength of the spring is 1400 MPa which is twice the bulk material, the strength of the interface is 70 MPa which is 5% of 1400 MPa. This is several times larger than the strength of the epoxy resin used in the resin 4c. Therefore, in the joint structure of the present embodiment, compared with the joint structure without the spring layer, high reliability can be obtained in the mode in which the interface between the member to be joined and the joint portion is peeled off as shown in Fig. 2(a).

Further, in the present embodiment, since the spring layer 4a provided on the surface of the lead frame 3 is fitted to the spring layer 4b provided on the surface of the heat radiation substrate 5, when the insulating layer 4 is broken, it is provided at least in the lead frame 3. On the side of the spring layer 4a provided on the surface of the heat release substrate 5, the spring layer 4a of the surface is broken. Therefore, the breaking strength of the joint portion including the joining layer 4 is at least equivalent to the strength of the spring layer.

As described above, the strength of the spring layer is several times larger than the strength of the epoxy resin used as the filling resin. Therefore, the joint structure of the present embodiment It is also possible to achieve high reliability in the mode in which the crack progresses inside the joint as shown in Fig. 2(b).

In the present embodiment, since the springs can be arranged closely, a large number of nanosprings can be disposed per unit volume per surface of the member to be joined. As a result, the joint area of the filling resin and the spring having a three-dimensional shape becomes large. The stress at the interface between the spring and the resin is the value of the load applied to the interface divided by the joint area. Therefore, in this embodiment, the joint area is large, and the stress at the interface can be greatly reduced. Therefore, the joint structure of the present embodiment can achieve high reliability even in the mode in which the interface between the spring and the filling resin is peeled off as shown in Fig. 2(c).

However, in the case of a joint structure of a macro scale, the stress is more significantly increased in the vicinity of the joint end than in other fields. This is because the stress distribution at the joint end becomes a specific stress singular field, and at the joint end of the dissimilar material, the stress is theoretically infinite. Generally speaking, the stress specificity is in the range of 10 to several 100 nm or more from the joint end. In the spring layer used in the present embodiment, the nano-structures are closely arranged, and a plurality of structures are disposed in a field where a large-scale becomes a specific field. Therefore, the stress singularity at the end of the spring layer does not occur remarkably, and the stress at the joint end can be prevented from increasing.

As described above, according to the joint structure of the present embodiment, high reliability can be obtained for any failure mode of the joint portion. That is, the strength of the joint itself or the interface between the joint portion and the member to be joined can be greatly improved.

Next, a method of manufacturing the joint structure of the present embodiment is shown in Figs. 3(a) to (c) and Figs. 4(a) to 4(c). Further, in the present production method, for example, a well-known nanostructure described in the literature, Takayuki Kitamura, et al, "FRACTURE NANOMECHANICS", PAN STANFORD PUBLISHING (2011), ISBN 978-981-4241-83-0 is used. Production method.

First, the surface layer 22 is formed by vacuum deposition as shown in Fig. 3(b) on the surface of the spring layer of the member 21 to be joined as shown in Fig. 3(a). This surface layer 22 is to improve the bonding property between the joined member 21 and the spring formed in the next process, and to rectify the surface roughness of the joined member 21 to be flattened. Next, as shown in FIG. 3(c), the vapor deposition atoms 23 are deposited by vacuum deposition from the oblique direction on the surface of the spring layer on which the member 21 to be joined is formed. At this time, while the member to be joined 21 is rotated, the vapor deposition atoms 23 are deposited, whereby atoms are deposited in a coil shape, and a coil-like spring layer 24 adhered or adhered to the surface of the member to be joined 21 is formed. Further, the spring is erected on the surface of the member to be joined 21 so that the longitudinal direction thereof can form a vertical direction on the surface of the member to be joined 21.

Next, as shown in FIG. 4(a), the member to be joined 21 and the member to be joined 31 are disposed so that the surfaces on which the respective nanospring layers are formed can be opposed. Next, as shown in FIG. 4(b), under the pressing and joining member 21 and the member to be joined 31, the spring layer 24 provided on the surface of the member to be joined 21 and the spring layer provided on the surface of the member to be joined 31 are provided. 32 will be mechanically fitted. Thereby, the two engaged members are engaged and positioned relative to each other. this When the member to be joined 21 and the member to be joined 31 are pressed in accordance with the shape of the spring, vibration is added by ultrasonic waves or the like, and the spring layers are more easily fitted to each other. Next, as shown in Fig. 4(c), the joined member 21 and the member to be joined 31 are more firmly joined under the fitting interspring inter-filling resin 33.

At this time, since the joined member 21 and the member to be joined 31 are joined by the fitting of the nanospring, the resin 33 can be joined without being filled. In this case, the joined member or the spring layer can be recovered without damage. Further, the presence or absence of the resin 33 can be appropriately selected in accordance with the use of the joint structure.

The mechanical properties of the spring layer will be described using Figs.

Fig. 5 is a photograph of a top surface and a cross-sectional photograph of a spring layer in which a nano-phase coil made of Ni is closely arranged. Each spring has a wire diameter of about 40 nm, a coil outer diameter of about 120 nm, a coil pitch of about 150 nm, and a height of about 400 nm. The present inventors reviewed the mechanical properties of the nanospring layer by advancing the indenter to the nanospring layer and the relationship between the load and the displacement.

Fig. 6 is a schematic view showing an indentation test apparatus for a nanospring layer. A device using a Triboscope manufactured by Hysitron Co., Ltd., which is a small load of 10 μN to 10 mN, was placed in an atomic force microscope to obtain a load-displacement relationship when a conical indenter was used to advance a spring layer having a radius of curvature of 10.44 μm. The displacement measurement decomposition energy was 0.2 nm. The measurement is carried out by the load control, and the same load is applied at 2 degrees. The elastic deformation range is determined when the load-displacement relationship does not change, and then the load is increased at the same position, and the same load is repeated again by 2 degrees. By repeating this procedure, the loaded load and the displacement at that time are obtained.

The measurement results are shown in Figs. 7(a) to (c). The vertical axis is the load and the horizontal axis is the displacement amount. Under the conditions of a load of 19.0 μN (Fig. 7(a)) and 20.2 μN (Fig. 7(b)), the relationship between the first and second load-displacement did not change and was in the range of elastic deformation. On the other hand, under the condition of a load of 22.0 μN (Fig. 7 (c)), the relationship between the first and second load-displacement changes, and it can be judged that the load is increased by the first load addition. When the test position was changed three times, the load after the drop was 21.9 μN, 15.2 μN, 10.6 μN, and the displacements for the load were 21.7 nm, 24.6 nm, and 20.8 nm, respectively. The average values were 15.9 μN and 22.4 nm, respectively.

The shear stress τ generated when the coil spring is only displaced by u is generally expressed by the following formula (1).

Here, G is the transverse elastic coefficient, d is the wire diameter, n is the effective number of rolls, and D is the average coil diameter. When the physical property value and size of the spring of the nanostructure are substituted in the formula (1), and the average value of the displacement of the plastic deformation is 22.4 nm in the displacement u, the shear stress τ generated by the plastic deformation is obtained. 759 MPa, if converted to the equivalent stress of Mises, becomes 1.32 GPa. This value is the relief stress of the material constituting the spring, which is more than twice as large as the relief stress of the Ni block. The lodging stress is larger than the bulk because the index from the surface is difficult to enter in the nanoscale configuration.

[Embodiment 2]

Fig. 8 is a schematic cross-sectional view showing a joint structure according to a second embodiment of the present invention. Unlike the first embodiment, the spring layer 24 provided on the surface of the member to be joined 21 is not mechanically fitted to the spring layer 32 provided on the surface of the member to be joined 31, and is perpendicular to the joint surface of the member to be joined. Separated, the joined members 21, 31 are joined by the resin 33.

In the present embodiment, although the spring layers are not fitted to each other, the joint layer is provided with a spring layer, and the interface between the member to be joined and the joint portion shown in Fig. 2(a) is peeled off, and Fig. 2 (c) The reliability of the mode in which the interface between the spring and the resin is peeled off is improved. When the member to be joined is joined by a resin, generally, the mode in which the crack is advanced in the resin as shown in Fig. 2(b) is smaller, and the mode of the interface peeling shown in Fig. 2 (a) or (c) is smaller. . Therefore, by applying the present embodiment to the bonding layer using the resin, the reliability of the two modes of Fig. 2 (a) or (c) is improved, and the reliability of bonding can be improved.

In Fig. 9, the known joint structure without a spring and the joint structure of a surface fastener having a millimeter-level spring having a spring are shown, and the properties of the joint structures of the first embodiment and the second embodiment of the present invention are shown.

The well-known joining structure which does not hold a spring is comprised only by the filling resin of low rigidity, and it is small in rigidity, and it is excellent in deformation absorption. The joint structure of the first and second embodiments of the spring holding the nanostructure is also because the rigidity of the nanospring is small, so that the deformation absorbability is good. On the other hand, in the joint structure of the millimeter-sized surface fastener, since the bending rigidity of the spring is proportional to the third power of the wire diameter, the millimeter-sized surface fastener having a large wire diameter is extremely rigid. Low deformation absorption. The stress generated in the spring is proportional to the second power of the wire diameter. Therefore, the joint structure of the spring holding the nanostructure is In other words, the stress generated by the spring is small, but in terms of the millimeter level, a very large stress is generated, and the spring itself is easily broken. Therefore, the height of the deformation absorbability which is one of the effects of the first and second embodiments can be achieved under the use of a nano-level spring layer.

With respect to the three types of joint layer failure modes shown in FIGS. 2(a) to 2(c), the known joint structure without the spring does not have the strength increase by the spring. In the joint structure of the spring of the millimeter-scale spring, the strength of the spring itself is large, but since the distance between the joint end and the spring is large, the prevention of the mode shown in Fig. 2(a) is difficult in the field without the spring. Further, compared with the spring of the nanometer type, since the surface area of the spring is small, the prevention effect of the mode shown in Fig. 2(c) is small. Based on these circumstances, the reliability improvement of the joint portion which is one of the effects of the first and second embodiments can be achieved under the use of a nano-level spring layer.

However, generally, a material such as tantalum nitride used in a spring has a large thermal conductivity as compared with a filled resin. Therefore, in comparison with the joint structure without the spring or the joint structure in which the upper and lower springs are not engaged, the millimeter-scale, nano-scale can reduce the thermal resistance of the joint structure of the spring-engagement.

Regarding insulation, any joint structure is ensured by adjustment of the thickness of the resin.

Regarding manufacturability, the joint structure that does not hold the spring or the joint structure in which the upper and lower springs are not engaged is small in the thickness direction, and the structure of the spring of the millimeter-scale or nano-scale is relatively large in thickness limitation. However, in the case of a spring- or nano-grade spring structure, since it can be joined at room temperature, the residual stress after joining can be reduced, and the resin can be recovered before filling. (repair).

In these cases, the first and second embodiments can be selectively used depending on the application in consideration of the above-described properties. Thereby, the reliability required for each use can be improved.

[Example 3]

Fig. 10 is a schematic cross-sectional view showing a joint structure according to a third embodiment of the present invention. This embodiment is a joint structure in which a resin and a flat member to be joined are joined, unlike the first and second embodiments. In the present embodiment, the coil-shaped spring layer 32 is provided only in the surface of the resin 33 and the member to be joined 31, the surface of the member to be joined 31, and extends in the resin 33 of the member to be joined. That is, the spring layer is an interface provided between the member to be joined 31 and the resin 33 which is the other joining member. According to the present embodiment, as in the second embodiment, high reliability can be obtained for the mode of Fig. 2 (a) or (c).

[Example 4]

The joint structure of the fourth embodiment of the present invention will be described with reference to Figs. 11 to 14 .

In the method for manufacturing a spring layer described with reference to FIGS. 3 and 4, when atoms are deposited by oblique vapor deposition, when the method of rotating the bonding member is controlled, the spring can be grown to be composed of a plurality of straight portions. More linear or polygonal.

Figure 11 shows a linear shape with two straight portions A cross-sectional photograph of a spring layer (hereinafter referred to as a two-linear shape) is an example of a spring layer having such a multi-linear nanostructure. If the spring is made linear or polygonal, the density of the spring can be increased, so that the reliability is improved or the thermal resistance is reduced.

12(a) to 12(c) show a joint structure of a spring layer having a plurality of linear portions (hereinafter referred to as a three-linear shape) having three straight portions.

As shown in Fig. 12 (a), the spring 32 (24) has a linear portion 32a (24a) extending from the surface of the member to be joined 31 (21) to the upper side (downward), and a straight portion 32a (24a). The upper end (lower end) extends to the upper (lower) straight portion 32b (24b), and the straight portion 32c (24c) that extends from the upper end (lower end) of the straight portion 32b (24b) to the upper (lower) portion. These three straight portions form a line shape which is connected to each other, thereby constituting one spring.

As shown in Fig. 12 (a), in a state in which the surface of the spring 24 provided with the three linear shapes in the member to be joined 21 and the surface of the spring 32 in which the three linear shapes are provided in the member to be joined 31 face each other, as shown in the figure As shown in FIG. 12(b), the member 21 to be joined and the member to be joined 31 are pressed. By the pressing force at this time, the spring is plastically deformed, and a large portion between the straight portions of the spring is generated. That is, the springs 24, 32 are deformed into hooks to create a place where they are stuck to each other. Thereby, the joined member 21 and the member to be joined 31 are joined with high reliability and positioned to each other. Further, as shown in Fig. 12(c), the reliability of joining is improved by filling the resin 33.

The two-linear spring shown in FIG. 11 can also be the same joint structure as when the three-linear spring shown in FIG. 12 is used. Further, as described below, it is preferable to use a straight portion having three straight lines or more. Spring.

FIGS. 13 and 14 are results of plastic deformation behaviors when a spring of a two-linear shape and a spring of a three-linear shape are simulated by a finite element method.

In the case of the two linear springs shown in Fig. 13, the straight portion b extends upward from the upper end of the straight portion a before being pressed, but is almost parallel to the surface of the member to be joined when pressed. Then, once the load is removed, the straight portion b is somewhat closer to the original shape by the rebound, and therefore extends upward from the upper end of the straight portion a as before the stacking. On the other hand, in the case of the three-linear spring shown in FIG. 14, the straight portion C extends upward from the upper end of the straight portion b before being pressed, but extends downward from the end of the straight portion b when pressed. . Even after being unloaded, the straight portion c maintains its extending direction. In other words, in the case of a multi-linear spring having three straight portions or more, after plastic deformation, the hook shape is larger than that of the two-linear spring. Therefore, the plurality of linear springs having three or more straight portions are more easily fitted to each other than the two linear springs. As a result, when a multi-linear spring having three or more straight portions is used, a highly reliable joint structure having a large joint strength can be obtained.

[Example 5]

15(a) to 15(c) are schematic cross-sectional views showing a joint structure of a fifth embodiment of the present invention. In the present embodiment, as shown in Fig. 15 (a), unlike the other embodiments, the surface of one of the joined members 21 is provided with a multi-linear (three-linear shape) spring layer 24, in another One side The surface of the member to be joined 31 is a spring layer 32 provided with a coil shape. That is, the shapes of the springs are different in the upper and lower joined members. As shown in Fig. 15 (b), in the present joint structure, the joint member is also pressed under the joint, and as shown in Fig. 14, the spring of the multi-linear shape is deformed into a hook shape having a large bending condition. When the deformed multi-linear spring is engaged with the coil-shaped spring, the engaged members 21, 31 are engaged and positioned to each other. Thereby, the joint strength is improved, and high joint reliability can be obtained. Also, it is possible to prevent looseness between the two members. Further, as shown in Fig. 15 (c), the reliability of joining is improved by filling the resin 33.

[Embodiment 6]

Fig. 16 is a schematic cross-sectional view showing a joined structure of a sixth embodiment of the present invention. Unlike the other embodiments, the spring layer 24 having a plurality of straight portions (hereinafter referred to as a four-linear shape) having four straight portions on the surface of the member to be joined 21 and the four straight lines provided on the surface of the member to be joined 31 are provided. The spring layer 32 is not mechanically fitted, and is vertically separated from the respective surfaces of the members to be joined 21, 31, and the joined members 21, 31 are joined by the resin 33.

In the present embodiment, although the spring layer is not fitted, the interface peeling of the joined portion shown in Fig. 2(a) and the interface between the spring and the filling resin shown in Fig. 2(c) are peeled off. The reliability of the mode can be improved. When joining by a resin, the mode of the interface peeling shown in Fig. 2 (a) or (c) is generally smaller than the mode in which the crack shown in Fig. 2 (b) progresses inside the resin. Therefore, with the present embodiment, the two modes of FIG. 2(a) or (c) are The reliability will increase, so the reliability of the bonding of the resin can be improved.

Further, under the use of a multi-linear spring, the density of the spring can be increased, so that the reliability of the joint is improved or the thermal resistance is reduced. Further, in the present embodiment, since the spring is not deformed, the same joint strength can be obtained as long as it has a multi-linear shape having two or more straight portions.

Further, any one of the spring layer 24 and the spring layer 32 may be changed into a coil-shaped spring layer as a modification of the embodiment.

[Embodiment 7]

Fig. 17 is a schematic cross-sectional view showing a joint structure of a seventh embodiment of the present invention. Unlike the other embodiments, a multi-linear (four-linear shape) spring layer is used in the joint structure in which the resin 33 and the flat-shaped member to be joined 31 are joined. In the present embodiment, the spring layer 32 is disposed only inside the surface of the resin 33 and the member to be joined 31, and the surface of the member to be joined. Thereby, high reliability can be obtained for the mode of Fig. 2 (a) or (c). Moreover, under the use of a multi-linear spring, the density of the spring can be increased, so that the reliability is improved or the thermal resistance is reduced more effectively.

[Embodiment 8]

Figure 18 is a cross-sectional schematic view showing a semiconductor device according to an eighth embodiment of the present invention. This embodiment is a resin molded semiconductor device. The semiconductor element 1 of the embodiment of Fig. 1, the surface of the lead frame 3 and the heat radiation substrate 5 are covered with a sealing resin 121. Unlike the first embodiment, the spring The layer is provided not only on the insulating layer 4 but also in the coil-like spring layer 4d at the interface between the lead frame 3 and the resin 121 (see an enlarged view in the drawing). By the spring layer 4d, the interface strength between the lead frame 3 and the sealing resin 121 is increased, and peeling of the lead frame 3 and the sealing resin 121 can be prevented.

Further, the present invention is not limited to the above-described respective embodiments, and various modifications are also included. For example, the above-described embodiments are described in detail for easy understanding of the present invention, and are not limited to all of the constituents having the description. Further, a part of the configuration of a certain embodiment may be replaced with a configuration of another embodiment, and a configuration of another embodiment may be added to the configuration of a certain embodiment. Further, it is possible to add another configuration to a part of the configuration of each embodiment. Remove. Replacement.

For example, the size, shape, and arrangement density of the spring may be different for each member to be joined or by the joint portion. The material of the spring is not limited to the above-described tantalum nitride or nickel, and a ceramic material such as aluminum nitride or a metal material such as copper can be used. That is, the size, shape, arrangement density, or material of the spring can be appropriately selected or changed in accordance with the mechanical strength, electrical characteristics, or thermal characteristics of the joint portion. Further, the member to be joined is applicable to various solid materials such as metal, resin, ceramics, and the like.

Further, in the semiconductor device of FIG. 1, a spring-like nanostructure composed of a metal having good solder wettability such as nickel is provided on the surface of the lead frame 3 and the semiconductor element 1, and the semiconductor can be secured. The electrical conductivity of the component 1 and the lead frame 3 improves the bonding strength. Further, the thermal resistance between the semiconductor element 1 and the lead frame 3 is reduced, and the heat dissipation property is improved. This configuration is, for example, one of the ones of FIG. The resin of the member to be joined is replaced with a solder.

1‧‧‧Semiconductor components

2‧‧‧Solder

3‧‧‧ lead frame

4‧‧‧Insulation

4a, 4b, 4d‧‧‧ spring layer

4c‧‧‧Resin

5‧‧‧Exothermic substrate

Claims (16)

A joint structure includes a first member, a second member, and a joint structure joining the joint portions of the first member and the second member, wherein the joint portion has a plurality of spring-like nanostructures . The joint structure of the first aspect of the invention, wherein the plurality of spring-like nanostructure systems are provided on at least one surface of the first member and the second member. The joint structure of the second aspect of the invention, wherein the joint portion has a spring-like nanostructure provided on a surface of the first member and a spring-shaped nanometer provided on a surface of the second member The structural systems are separated from each other and filled with a resin. The joint structure of the second aspect of the invention, wherein the joint portion has a spring-like nanostructure provided on a surface of the first member and a spring-shaped nanometer provided on a surface of the second member The structural systems are fitted to each other. The joint structure of the third aspect of the invention, wherein at least one of a spring-like nanostructure provided on a surface of the first member and a spring-shaped nanostructure provided on a surface of the second member is Coil shaped. The joint structure of the third aspect of the invention, wherein at least one of a spring-like nanostructure provided on a surface of the first member and a spring-shaped nanostructure provided on a surface of the second member is A plurality of linear portions having a plurality of straight portions. Such as the joint structure of claim 4, wherein At least one of the spring-like nanostructure of the surface of the first member and the spring-like nanostructure provided on the surface of the second member has a coil shape. The joint structure of the fourth aspect of the invention, wherein at least one of a spring-like nanostructure provided on a surface of the first member and a spring-shaped nanostructure provided on a surface of the second member is It has a multi-linear shape with a plurality of straight portions. The joint structure of claim 6 or 8, wherein the multi-linear system has three or more straight portions. The joint structure of the third or fourth aspect of the invention, wherein the spring-like nanostructure provided on the surface of the first member and one of the spring-shaped nanostructures provided on the surface of the second member It is a multi-linear shape having a plurality of straight portions, and the other is a coil shape. The joint structure of claim 10, wherein the multi-linear system has three or more straight portions. The joint structure of the third aspect of the invention, wherein the spring-shaped nanostructure system is made of an insulating ceramic, and is further filled with an insulating resin, and the first member and the second member are It is joined by the above-described joint portion having insulation properties. The joint structure of the fourth aspect of the invention, wherein the spring-shaped nanostructure system is made of an insulating ceramic, the resin is an insulating resin, and the first member and the second member are It is joined by the above-described joint portion having insulation properties. The joint structure of claim 11 or 12, wherein the ceramic is tantalum nitride. A semiconductor device comprising: a semiconductor element; a lead frame for bonding the semiconductor element; and a heat radiation substrate bonded to the lead frame, wherein a joint portion between the lead frame and the heat radiation substrate is a plurality of spring-like Rice structure. A semiconductor device comprising: a semiconductor element; a lead frame for bonding the semiconductor element; a heat radiation substrate bonded to the lead frame; and a resin covering the semiconductor element and the lead frame and each surface of the heat radiation substrate, wherein: A plurality of spring-like nanostructures are provided at the interface between the lead frame and the resin.