Electronic module

Abstract

To provide an electronic module that can ensure a predetermined solder thickness on an outer peripheral part of a spacer that is a thermal stress concentration part in a joining part of the spacer and an electronic element, and alleviate thermal stress occurring on the outer peripheral part of the spacer.SOLUTION: An electronic module 100 comprises an internal connection terminal 134 electrically connected to an electronic element 120 and having conductivity, and a spacer 122 is arranged between a lower end face of the internal connection terminal 134 and the electronic element 120. Solder BM1 is arranged between the electronic element 120 and the spacer 122, and a step part 117 is formed along an outer peripheral part 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 mounted, 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.

[0003] 7, the electronic element 320 is disposed on the substrate 312 and is joined to the substrate 312 via solder BM30. The chip spacer 318 is disposed on the electronic element 320 and is joined to the electronic element 320 via solder BM10. The lower ends of the internal connection terminals 334 are disposed on the chip spacer 318 and are joined to the chip spacer 318 via solder BM20. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6850938 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when large electronic components are mounted or when high reliability is required, it is necessary to further reduce the thermal stress. Therefore, it is necessary to ensure a certain solder thickness around the outer periphery of the spacer, which is the thermal stress concentration area at the joint between the spacer and the electronic component.

[0006] On the other hand, there is a limit to the amount of solder that can be applied to the electrodes of an electronic element in order to prevent solder bridging between different electrodes on the electronic element, and with the conventional structure described above, it is difficult to ensure a sufficient solder thickness on this outer periphery.

[0007] Therefore, the object of the present invention is to provide an electronic module that can ensure a predetermined solder thickness on the outer periphery of the spacer, which is a thermal stress concentration area at the joint between the spacer and the electronic element, and can alleviate the thermal stress that occurs on the outer periphery of the spacer. [Means for solving the problem]

[0008] The electronic module of the present invention is an electronic module comprising an internal connection terminal electrically connected to an electronic element and having conductivity, and a spacer (chip spacer) arranged between the lower end surface of the internal connection terminal and the electronic element, in which a conductive bonding material is arranged between the electronic element and the spacer, and a step portion is formed along the outer periphery of the spacer. [Effects of the Invention]

[0009] The electronic module of the present invention includes an electronic element, an internal connection terminal electrically connected to the electronic element and having conductivity, and a spacer disposed between the lower end surface of the internal connection terminal and the electronic element. A conductive bonding material is disposed between the electronic element and the spacer, and a step portion is formed along the outer periphery of the spacer, creating a space for ensuring a solder thickness between the step portion formed on the outer periphery of the spacer and the electronic element. This ensures a predetermined solder thickness on the outer periphery of the spacer, which is a thermal stress concentration area. Therefore, thermal stress occurring on the outer periphery of the spacer at the joint between the spacer and the electronic element can be alleviated. [Brief explanation of the drawings]

[0010] [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 a spacer 122 according to an embodiment of the present invention, in which 135 denotes a flange portion and 144 denotes an internal connection terminal. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 5] FIG. 2 is a perspective view showing the structure of the lower surface of a spacer 122 in the embodiment. [Figure 6] FIG. 2 is a perspective view showing the structure of the upper surface of a spacer 122 in the embodiment. [Figure 7] 1A and 1B are diagrams illustrating an electronic module according to a conventional technique. DETAILED DESCRIPTION OF THE INVENTION

[0011] The electronic module of the present invention will be described below based on the embodiments shown in 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.

[0012] [Embodiment] 1 to 3, an electronic module 100 according to the embodiment includes a substrate (first substrate) 112, an electronic element 120, a spacer (chip spacer) 122, internal connection terminals 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 (see FIG. 4), and an electronic element (semiconductor element; not shown) is bonded to the lower surface of the substrate 140 via solder.

[0013] In the embodiment, the electronic module 100 is for configuring a half-bridge circuit, and for example, the electronic element 120 is used as the high side, and the electronic element bonded to the lower surface of the substrate 140 is used as the low side. Note that there is also a case where the electronic element 120 is used as the low side, and the electronic element bonded to the lower surface of the substrate 140 is used as the high side. The electronic module 100 may include components other than those described above. For convenience, the following will describe the components of the electronic element 120 of the electronic module 100, and will omit a detailed description of the components of the electronic element bonded to the lower surface of the substrate 140. In this specification, "electrically connected" includes not only cases where current-carrying parts of the components are in direct contact with each other, but also cases where the components are connected via other conductive components (for example, solder or a spacer).

[0014] 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.

[0015] 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 side opposite to the substrate 112, 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.

[0016] The internal connection terminal 134 is a conductive, generally columnar member (see FIG. 4), and is connected to a flat spacer 122 made of a conductive material via a through-hole (reference numeral omitted) formed in the external connection terminal 161. The internal connection terminal 134 connects the substrate 112 to the substrate 140. The electronic module 100 also includes 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 taking 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.

[0017] The lower surface of the spacer 122 is joined to the source electrode 123 of the electronic element 120 via a conductive joining member (e.g., solder) BM1. The upper surface of the spacer 122 is joined to the lower end surface of the internal connection terminal 134 via solder BM2.

[0018] The external connection terminal 161 is electrically connected to the internal connection terminal 134, and is a member having at least one end protruding from 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.

[0019] (Spacer structure) As shown in FIGS. 5 and 6, the spacer 122 is formed by processing a thin, conductive flat plate (here, a copper plate) into a polygonal shape. Three annular recesses (recesses) 113, each having an outer diameter larger than the diameter of the internal connection terminal 134, are formed on the upper surface of the spacer 122 (see FIG. 6). The spacer 122 is bonded to the lower surface of the internal connection terminal 134 at the recesses 113 via a conductive bonding material (e.g., solder BM2). The recesses 113 are formed by applying a force vertically downward by hammering from above. The external shape of the recesses 113 corresponds to the cross-sectional shape of the internal connection terminal 134, and the outer diameter and depth can be changed depending on the shape of the internal connection terminal 134. The lower surface of the spacer 122 is bonded to the upper surface of the electronic element 120 (specifically, the source electrode 123) via a conductive bonding material (e.g., solder BM1).

[0020] Since the spacer 122 has an annular recess 113 formed therein, the recess 113 has an outer diameter larger than the diameter of the internal connection terminal 134, and this recess 113 can prevent the solder BM2 from flowing outward in the radial direction from between the upper surface of the spacer 122 and the lower surface of the internal connection terminal 134.

[0021] 5, a step portion (squashed portion) 117 is formed along the outer periphery of the spacer 122. This creates a space between the step portion 117 formed on the outer periphery of the spacer 122 and the electronic element 120, and the solder thickness between the lower surface of the spacer 122 and the electronic element 120 at the outer periphery can be made larger than in a conventional spacer that does not have a step portion.

[0022] A protrusion 115 is formed on the bottom surface of the spacer 122 to bring the internal connection terminal 134 into point contact with the source electrode 123 of the electronic element 120 via the spacer 122. The presence of the protrusion 115 makes it possible to maintain a constant distance between the electronic element 120 and the portion of the bottom of the spacer 122 other than the protrusion 115, and therefore makes it possible to maintain a constant solder thickness of the solder BM1 disposed between the spacer 122 and the electronic element 120 (see FIG. 4).

[0023] Furthermore, the positions where the depressions 113 and the protrusions 115 are formed are preferably positions corresponding to the positions of the internal connection terminals 134 and are formed inside the outer periphery of the spacer 122. It is preferable that the number of depressions 113 and the number of protrusions 115 formed are at least three, for example. This is because this allows the spacer 122 to stand upright. Note that, in order to make the spacer 122 self-standing, it is necessary that three or more protrusions 115 are not arranged in a straight line.

[0024] [Effects of the embodiment] The electronic module 100 according to the embodiment includes an electronic element 120, conductive internal connection terminals 134 electrically connected to the electronic element 120, and a spacer 122 disposed between the electronic element 120 and the lower end surface of the internal connection terminal 134. Solder BM1 is disposed between the electronic element 120 and the spacer 122, and a step 117 is formed along the outer periphery of the spacer 122. This creates a space between the step 117 formed on the outer periphery of the spacer 122 and the electronic element 120 to ensure a certain solder thickness. This ensures that a certain solder thickness is achieved on the outer periphery of the spacer 122, which is a thermal stress concentration area. This makes it possible to alleviate thermal stress occurring on the outer periphery of the spacer 122 at the joint between the spacer 122 and the electronic element 120.

[0025] Furthermore, in the electronic module 100 according to the embodiment, the convex portions 115 are formed on the lower surface of the spacer 122 for electrically connecting the internal connection terminals 134 and the electronic element 120. Therefore, the presence of the convex portions 115 makes it possible to maintain a constant distance between the electronic element 120 and the portion of the bottom of the spacer 122 other than the convex portions 115. This makes it possible to maintain a constant solder thickness of the solder BM1 disposed between the portion of the bottom of the spacer 122 other than the convex portions 115 and the electronic element 120. Furthermore, the convex portions 115 make it possible to cause the self-alignment of the solder BM1 during aggregation to act toward the axial center of the internal connection terminals 134.

[0026] Furthermore, according to the electronic module 100 of the embodiment, at least three protrusions 115 are formed, so that the spacer 122 can stand upright.

[0027] Furthermore, in the electronic module 100 according to the embodiment, annular recesses 113 having an outer diameter larger than the diameter of the internal connection terminals 134 are formed on the upper surface of the spacer 122, and the recesses 113 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]

[0028] 100...electronic module, 113...dent (recess), 115...projection, 117...step, 120...electronic element, 122...spacer, 134...internal connection terminal

Claims

1. An electronic module comprising: an electronic element; an internal connection terminal electrically connected to the electronic element and having conductivity; and a spacer disposed between a lower end surface of the internal connection terminal and the electronic element, a conductive bonding material is disposed between the electronic element and the spacer; A step portion is formed along the outer periphery of the spacer.

1. An electronic module comprising:

2. A convex portion is formed on the surface of the spacer facing the electronic element.

2. The electronic module of claim 1.

3. At least three of the protrusions are formed.

3. Electronic module according to claim 1 or 2.

4. An annular recess having an outer diameter larger than the diameter 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.

3. Electronic module according to claim 1 or 2.

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