Electronic module

Abstract

To provide an electronic module that can alleviate thermal stress in a conductive joint material between an internal connection terminal and a spacer, and can prevent the occurrence of loose contact between the internal connection terminal and the spacer.SOLUTION: An electronic module 100 comprises: an electronic element 120 having an electrode 123; an internal connection terminal 134 electrically connected to the electrode 123 of the electronic element 120 and having conductivity; and a spacer 122 arranged between the internal connection terminal 134 and the electronic element 120. A conductive joint material BM2 is arranged between the internal connection terminal 134 and the spacer 122. A projection 137 is formed on a surface of the internal connection terminal 134 facing the electronic element 120. A leading end of the projection 137 is in contact with a top face of the spacer 122.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an electronic module. [Background technology]

[0002] Conventionally, electronic modules have been known that include an electronic element (e.g., a chip), a substrate on which the electronic element is arranged, and pin terminals as internal connection terminals connected to wiring patterns on the substrate (see Patent Document 1 below). In some electronic modules of this type, the internal connection terminals are connected to electrodes of the electronic element rather than to the wiring pattern. In some such electronic modules, the internal connection terminals are connected to electrodes of the electronic element via flat spacers (e.g., chip spacers). In this case, the spacer and the electrodes of the electronic element are joined by solder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6850938 Summary of the Invention [Problem to be solved by the invention]

[0004] Spacers (e.g., chip spacers) are used to relieve thermal stress on the chip surface. However, when internal connection terminals are bonded to these spacers, external temperature changes can cause thermal stress in the conductive bonding material (solder) between the spacer and the internal connection terminals. This can lead to cracks in the conductive bonding material (solder) between the spacer and the internal connection terminals, potentially increasing electrical resistance and reducing the heat dissipation performance of the electronic device (e.g., chip). Furthermore, the flat tip of the internal connection terminal can lead to loose contact between the internal connection terminal and the spacer. While the above-mentioned problem applies when a spacer is present, it can also occur when a spacer is not present, for example, when the tip of the internal connection terminal is bonded to an electrode (conductive part) of the electronic device via a conductive bonding material.

[0005] Therefore, the object of the present invention is to provide an electronic module that can alleviate thermal stress in the conductive bonding material between the internal connection terminal and the spacer (electrode) and suppress the occurrence of loose contact between the internal connection terminal and the spacer. [Means for solving the problem]

[0006] The electronic module of the present invention is an electronic module comprising an electronic element having an electrode, an internal connection terminal electrically connected to the electrode of the electronic element and having conductivity, and a spacer arranged between the internal connection terminal and the electronic element, wherein a conductive bonding material is arranged between the internal connection terminal and the spacer, and a convex portion is formed on the surface of the internal connection terminal facing the electronic element, and the tip of the convex portion is in contact with the upper surface of the spacer. [Effects of the Invention]

[0007] The electronic module of the present invention comprises an electronic element having an electrode, an internal connection terminal electrically connected to the electrode of the electronic element and having conductivity, and a spacer arranged between the internal connection terminal and the electrode of the electronic element, and a conductive bonding material is arranged between the internal connection terminal and the spacer, and a convex portion is formed on the surface of the internal connection terminal facing the electronic element, thereby making it possible to alleviate thermal stress generated in the conductive bonding material (e.g., solder) between the outer periphery of the internal connection terminal, where thermal stress is concentrated, and the spacer.

[0008] Furthermore, since the tip of the protrusion is in contact with the upper surface of the spacer, the contact point between the tip of the protrusion and the upper surface of the spacer becomes the joining starting point, thereby preventing loose contact between the internal connection terminal and the spacer. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view of the appearance of an electronic module 100 according to an embodiment. [Figure 2] 1 is a perspective view showing the internal structure of an electronic module 100 according to an embodiment. [Figure 3] 1 is a perspective view illustrating the peripheral structure of an internal connection terminal 134 in the embodiment, where 135 is a flange portion and 144 is an internal connection terminal. [Figure 4] 10 is a diagram for explaining the structure between the internal connection terminal 134 and the spacer 122. FIG. [Figure 5] FIG. 2 is a perspective view showing the structure of the upper surface of a spacer 122 in the embodiment. [Figure 6] 6A and 6B are diagrams showing the structure of an internal connection terminal 134 according to an embodiment. Fig. 6A is a perspective view showing the structure of the bottom surface of the internal connection terminal 134 according to the embodiment. Fig. 6B is a side view of the internal connection terminal 134 according to the embodiment. [Figure 7] 7A and 7B are diagrams showing the structure of an internal connection terminal 138 in a modified example. Fig. 7A is a perspective view showing the structure of the lower surface of the internal connection terminal in the modified example. Fig. 7B is a side view of the internal connection terminal in the modified example. [Figure 8]10A and 10B are diagrams illustrating modified examples of the electronic module. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the electronic module of the present invention will be described with reference to the drawings. The embodiments described below do not limit the invention according to the claims. Furthermore, not all of the elements and combinations thereof described in the embodiments are necessarily essential to the solution of the present invention.

[0011] [Embodiment] 1 to 4, an electronic module 100 according to the embodiment includes a substrate (first substrate) 112, an electronic element 120 having an electrode (for example, a source electrode, described later) 123, a spacer (chip spacer) 122, an internal connection terminal 134, a substrate (second substrate) 140, lead frames (constituting external connection terminals; hereinafter, referred to as "external connection terminals") 160, 161, 162, 163, 164, 165, and 166, and a mold resin 150. The external connection terminal 161 is connected to the internal connection terminal 134 at a midpoint of the internal connection terminal 134. An electronic element (semiconductor element) 120 is bonded to the upper surface of the substrate 112 via solder BM3, and an electronic element (semiconductor element; not shown) is bonded to the lower surface of the substrate 140 via solder.

[0012] In the embodiment, the electronic module 100 is configured to form a half-bridge circuit, in which the electronic element 120 is used as a high side and an electronic element bonded to the lower surface of the substrate 140 is used as a low side. Note that there is also a case where the electronic element 120 is used as a low side and an electronic element bonded to the lower surface of the substrate 140 is used as a high side. Note that the electronic module 100 may include components other than those described above. For convenience, the following describes the components of the electronic element 120 of the electronic module 100, and a detailed description of the components of the electronic element bonded to the lower surface of the substrate 140 is omitted. In this specification, "electrically connected" includes not only a case where current-carrying parts of the components are in direct contact with each other, but also a case where they are connected via another conductive component (for example, solder or a spacer). Other than a half-bridge, a full-bridge circuit or other appropriate configuration may also be used.

[0013] The substrate 112 has a structure in which copper plates are arranged on both sides of a ceramic plate (for example, a DCB substrate). The substrate 112 is electrically connected to a drain electrode (not shown) of the electronic element 120. Note that the substrate 112 is not limited to a DCB substrate and may be, for example, a printed circuit board or the like.

[0014] The electronic element 120 is disposed on the substrate 112. The electronic element 120 is a vertical MOSFET having a source electrode 123 disposed on the substrate 112 side, a drain electrode (not shown) disposed on the substrate 112 side, and a gate electrode 127 disposed on the same side as the source electrode 123 (see FIG. 3). The electronic element 120 has three source electrodes 123 as source electrodes. Note that the electronic element 120 may be another semiconductor element such as an IGBT, a triac, or a diode, or may be an electronic element other than a semiconductor element such as a capacitor or an inductor. Furthermore, the number of electronic elements is not limited to two, and may be one, or three or more.

[0015] The internal connection terminal 134 is a conductive, generally columnar member (see FIG. 4 ) and is electrically connected to an electrode (e.g., source electrode) 123 of the electronic element 120. The internal connection terminal 134 is connected to a flat, later-described spacer 122 made of a conductive material via a conductive bonding material (e.g., solder) BM2. The electronic module 100 is provided with three internal connection terminals 134 corresponding to the three source electrodes 123 of the electronic element 120. Note that, although the embodiment has been described using a generally columnar member as an example, the internal connection terminal is not limited to a generally columnar internal connection terminal and may be, for example, a flat-plate internal connection terminal. Furthermore, although the embodiment has been described using a circular cross-sectional shape as an example, the cross-sectional shape of the internal connection terminal is not limited thereto and may be, for example, a rectangular cross-sectional shape.

[0016] As shown in FIG. 6 , a truncated cone-shaped tapered portion 136 is formed on the portion of the internal connection terminal 134 on the electronic element 120 side (the portion on the source electrode 123 side). A dome-shaped protrusion 137 is formed in the center of the tapered portion 136. The tip (top) of the protrusion 137 is in contact with the spacer 122. A conductive bonding material (e.g., solder) BM2 is disposed between the portion of the protrusion 137 other than the tip and the spacer 122, bonding the internal connection terminal 134 and the spacer 122. The tip of the protrusion 137 and the spacer 122 may be in direct contact or may be in contact via a relatively thin conductive bonding material (e.g., solder). The solder BM2 is applied from the tip of the protrusion 137 of the internal connection terminal 134 through the tapered portion 136 to near the outer periphery. Note that near the outer periphery includes a case where the solder BM2 is applied from the tip of the protrusion 137 to partway along the tapered portion 136.

[0017] The spacer 122 is disposed between the internal connection terminals 134 and the electronic element 120. As shown in FIG. 5, the spacer 122 is formed in a polygonal shape from a thin, conductive flat plate material (copper plate in this case). Three annular depressions (recesses) 128, each having an outer diameter larger than the diameter of the internal connection terminals 134, are formed on the upper surface of the spacer 122. The tips (tops) of the protrusions 137 of the internal connection terminals 134 are in contact or direct contact with the upper surface of the spacer 122 (specifically, the upper surface corresponds to the bottom surface of the depressions 128) via a conductive bonding material (e.g., solder) BM2 (see FIG. 4). The number of depressions 128 is not limited to three, and it is desirable to form the same number of depressions as the number of internal connection terminals 134.

[0018] The external shape of the recess 128 corresponds to the cross-sectional shape of the internal connection terminal 134, and the outer diameter and depth thereof can be changed according to the shape of the internal connection terminal 134. The lower surface of the spacer 122 is joined to the upper surface (specifically, the source electrode 123) of the electronic element 120 via a conductive bonding material (for example, solder BM1). In the embodiment, the external shape of the spacer 122 has been described as being polygonal, but is not limited to this.

[0019] The external connection terminal 161 is a member that is electrically connected to the internal connection terminal 134 between the substrate 140 and the electronic element 120, and at least one end of which protrudes outside the mold resin 150. The external connection terminal 161 in the electronic module 100 is a detection terminal for the source electrode 123 of the electronic element 120.

[0020] [Effects of the embodiment] The electronic module according to the embodiment includes an electronic element 120 having electrodes 123, internal connection terminals 134 electrically connected to the electrodes 123 of the electronic element 120 and having conductivity, and a spacer 122 arranged between the internal connection terminals 134 and the electrodes 123 of the electronic element 120, a conductive bonding material BM2 is arranged between the internal connection terminals 134 and the spacer 122, and a convex portion 137 is formed on the surface of the internal connection terminals 134 facing the electronic element 120. As a result, the solder thickness of the solder BM2 is thicker near the outer periphery than at the tips of the convex portions 137 of the internal connection terminals 134, and this ensures that the solder thickness is sufficient near the outer periphery of the internal connection terminals 134 where thermal stress concentrates, thereby mitigating the thermal stress acting on the solder BM2 joining the internal connection terminals 134 and the spacer 122.

[0021] Furthermore, since the tip of the protrusion 137 is in contact with the upper surface of the spacer 122, the contact point between the tip of the protrusion 137 and the upper surface of the spacer 122 becomes the joining starting point. This makes it possible to prevent loose contact between the internal connection terminal 134 and the spacer 122.

[0022] Furthermore, according to the electronic module of the embodiment, the protrusion 137 is formed in the center of the tip of the internal connection terminal 134, and therefore can be brought into point contact with the connection member (spacer 122 or electrode 123) located below it. Therefore, this contact portion serves as the joining starting point, and the occurrence of loose contact between the internal connection terminal 134 and the spacer 122 can be more reliably prevented.

[0023] Furthermore, in the electronic module 100 according to the embodiment, the portion of the internal connection terminal 134 on the electronic element 120 side is tapered. Therefore, the thickness of the solder BM2 that is applied from the center of the protrusion 137 of the internal connection terminal 134, via the tapered portion 136, to the outer periphery is thicker on the outer periphery side of the internal connection terminal 134 than on the tip of the protrusion 137. This ensures a sufficient solder thickness near the outer periphery of the spacer 122 where thermal stress concentrates, and as a result, it is possible to more reliably alleviate the thermal stress acting on the solder BM2 that joins the internal connection terminal 134 and the spacer 122.

[0024] Although the present invention has been described above based on the above embodiment, the present invention is not limited to the above embodiment and can be embodied in various forms without departing from the spirit of the present invention, and for example, the following modifications are also possible.

[0025] (Modification of the tip shape of the internal connection terminal) 7(a) and 7(b), the tip of the internal connection terminal 138 has a shape in which a cylindrical protrusion 139 is formed in the center of the lower surface of a truncated cone-shaped tapered portion 136. The protrusion 139 is formed in the center of the tip of the internal connection terminal 138. Note that the tip shape is not limited to the above, and may be any shape that tapers toward the tip, for example.

[0026] (Modification of Electronic Module) In the above-described embodiment, an electronic module in which a spacer is disposed between the internal connection terminal and the electronic element is described. On the other hand, in the modified example, the shape of the internal connection terminal is the same as that of the internal connection terminal in the above-described embodiment, but the internal connection terminal differs from the above-described embodiment in that a spacer is not disposed between the internal connection terminal and the electronic element, and the internal connection terminal is connected to the electrode of the electronic element via a conductive bonding material. The modified example will be described below with reference to FIG. 8.

[0027] In the modified example, the internal connection terminals are connected to the electrodes of the electronic elements via a conductive bonding material without providing a spacer, and therefore only the different parts will be described, and a description of similar parts will be omitted. Furthermore, the same reference numerals may be used for similar parts when there is no need to distinguish them. In addition, the modified example has the same configuration as the electronic module 100 according to embodiment 1 except for the internal connection terminals being connected to the electrodes of the electronic elements via a conductive bonding material without providing a spacer, and therefore has the corresponding effects of the electronic module 100 according to embodiment 1.

[0028] A protrusion 137 is formed on the portion of the internal connection terminal 134 on the electronic element 120 side (the portion on the source electrode 123 side). A dome-shaped protrusion 137 is formed in the center of the tapered portion 136. The tip (top) of the protrusion 137 is in contact with or direct contact with the source electrode 123 arranged on the upper surface of the electronic element 120 via a conductive bonding material (e.g., solder) BM2. With this structure, the thickness of the solder BM2 that is piled from the center of the protrusion 137 of the internal connection terminal 134 through the tapered portion 136 to the outer periphery becomes thicker on the outer periphery side of the internal connection terminal 134 (see FIG. 4).

[0029] Therefore, the solder thickness can be ensured between the vicinity of the outer edge of the internal connection terminal 134, where thermal stress is concentrated, and the electrode 123, and as a result, the thermal stress acting on the solder BM2 joining the internal connection terminal 134 and the electrode 123 can be alleviated.

[0030] Furthermore, since a protrusion 137 is formed on the tip side of the internal connection terminal 134, the protrusion 137 can be brought into point contact with the electrode 123 of the electronic element 120. Therefore, this contact portion serves as the joining starting point, and the occurrence of loose contact between the internal connection terminal 134 and the electrode 123 can be suppressed.

[0031] The electronic module according to the modified example includes an electronic element 120 having an electrode 123, and an internal connection terminal 134 that is electrically connected to the electrode 123 of the electronic element 120 and has conductivity, with a conductive bonding material BM2 disposed between the internal connection terminal 134 and the electrode 123 of the electronic element 120. A convex portion 137 is formed on the surface of the internal connection terminal 134 that faces the electronic element 120, and the tip of the convex portion 137 is in contact with the electrode 123 of the electronic element 120. As a result, the solder thickness of the solder BM2 is thicker near the outer periphery than at the tip of the convex portion 137 of the internal connection terminal 134, and this ensures that the solder thickness is sufficient near the outer periphery of the internal connection terminal 134 where thermal stress concentrates. As a result, it is possible to alleviate the thermal stress acting on the solder BM2 that joins the internal connection terminal 134 to the electrode 123.

[0032] Furthermore, since the tip of the protrusion 137 is in contact with the upper surface of the electrode 123 of the electronic element 120, the contact point between the tip of the protrusion 137 and the upper surface of the electrode 123 becomes the joining starting point. This makes it possible to prevent loose contact between the internal connection terminal 134 and the electrode 123.

[0033] Furthermore, in the electronic module 100 according to the embodiment, recesses 128 having a shape corresponding to the cross-sectional shape of the internal connection terminals 134 are formed on the upper surface of the spacer 122, and the recesses 128 are formed at positions corresponding to the positions of the internal connection terminals 134. Therefore, a self-alignment effect is obtained with respect to the internal connection terminals 134 inserted into the lead frame 161, and it is possible to prevent the spacer 122 from shifting in position. [Explanation of symbols]

[0034] 100...electronic module, 120...electronic element, 122...spacer, 123...electrode, 128...dent (recess), 134, 136...internal connection terminal, 137...projection

Claims

1. An electronic module comprising: an electronic element having an electrode; an internal connection terminal electrically connected to the electrode of the electronic element and having conductivity; and a spacer disposed between the internal connection terminal and the electrode of the electronic element, a conductive bonding material is disposed between the internal connection terminal and the spacer; a protrusion is formed on a surface of the internal connection terminal facing the electronic element, and a tip of the protrusion is in contact with an upper surface of the spacer; 1. An electronic module comprising:

2. An electronic module comprising: an electronic element having an electrode; and an internal connection terminal electrically connected to the electrode of the electronic element and having conductivity, a conductive bonding material is disposed between the internal connection terminal and the electrode of the electronic element; a protrusion is formed on a surface of the internal connection terminal facing the electronic element, and a tip of the protrusion is in contact with an electrode of the electronic element; 1. An electronic module comprising:

3. the protrusion is formed at the center of the tip of the internal connection terminal; 3. An electronic module according to claim 1 or 2.

4. a portion of the internal connection terminal on the electronic element side having a tapered shape; 3. An electronic module according to claim 1 or 2.

5. a recess having a shape corresponding to the cross-sectional shape of the internal connection terminal is formed on the upper surface of the spacer, and the recess is formed at a position corresponding to the position of the internal connection terminal; 2. The electronic module of claim 1.

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