Electronic module

Abstract

[Problem] To provide an electronic module that suppresses mispositioning of an internal connection terminal and a chip spacer, suppresses rotation of the chip spacer when solder is melted, and improves desired self-alignment effects. [Solution] An electronic module 100 comprises an electronic element 120, at least one conductive internal connection terminal 134 that is electrically connected to the electronic element 120, and a chip spacer 122 that is formed between the electronic element 120 and a lower end surface of the internal connection terminal 134. The chip spacer 122 is bonded to the electronic element 120 via a conductive bonding material BM1, and at least one recess 113 that has a larger diameter than the internal connection terminal 134 is formed in an upper surface of the chip spacer 122.

Description

Electronic Module

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

[0002] Conventionally, electronic modules have been known that include a semiconductor element and internal connection terminals that connect electrodes of the semiconductor element to wiring patterns on a substrate. Meanwhile, electronic modules have also been known that include a semiconductor element, a substrate on which the semiconductor element is mounted, pin terminals serving as internal connection terminals connected to the wiring patterns on the substrate, and a lead frame that supports the pin terminals and electrically connects the electrodes of the semiconductor element to the pin terminals (see Patent Document 1 below). Among these types of electronic modules, some have internal connection terminals that are connected to electrodes of the semiconductor element rather than to the wiring patterns. One such electronic module may be one in which the semiconductor element is connected to the internal connection terminals via chip spacers to relieve stress.

[0003] Incidentally, as shown in FIG. 5, an electronic module is also known in which a semiconductor element 320 is bonded onto an insulating substrate 312 via a solder BM 30, and a chip spacer 318 is bonded via a solder BM 20 to the lower end of an internal connection terminal 334 inserted into a through hole (not shown) formed in a lead frame (not shown).

[0004] Patent No. 6850938

[0005] However, during the process of joining the internal connection terminals 334 and the chip spacers 318, the solder BM20 between the internal connection terminals 334 and the chip spacers 318 flows out, causing misalignment between the internal connection terminals 334 and the chip spacers 318 when the solder melts, making it difficult to achieve the desired self-alignment effect.

[0006] Furthermore, when using chip spacer 318 as a buffer material, in the case of a chip having electrodes on its surface, it was necessary to increase the size of chip spacer 318 in accordance with the number of chip electrodes in order to reduce the resistance component. In this case, it was a challenge to realize a structure that would prevent misalignment between internal connection terminal 334 and chip spacer 318 and suppress rotation of chip spacer 318 when solder melts.

[0007] SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an electronic module that can suppress misalignment between the internal connection terminals and the chip spacers and improve the desired self-alignment effect.

[0008] Another object of the present invention is to provide an electronic module that can suppress misalignment between the internal connection terminals and the chip spacer, and rotation of the chip spacer when the solder melts, when the shape of the chip spacer is increased in accordance with the number of chip electrodes, thereby improving the desired self-alignment effect.

[0009] The electronic module of the present invention comprises an electronic element, at least one internal connection terminal electrically connected to the electronic element and having conductivity, and a chip spacer formed between the lower end surface of the internal connection terminal and the electronic element, wherein the chip spacer is bonded to the electronic element via a conductive bonding material, and at least one recess having a diameter larger than that of the internal connection terminal is formed on the upper surface of the chip spacer.

[0010] According to the electronic module of the present invention, at least one recess having a diameter larger than that of the internal connection terminal is formed on the upper surface of the chip spacer, thereby providing an electronic module that suppresses misalignment between the internal connection terminal and the chip spacer and improves the desired self-alignment effect.

[0011] Furthermore, according to the electronic module of the present invention, when the shape of the chip spacer is increased in accordance with the number of chip electrodes, it is possible to provide an electronic module that can suppress misalignment between the internal connection terminal and the chip spacer, and rotation of the chip spacer when the solder melts, thereby improving the desired self-alignment effect.

[0012] 2(a) is a plan view showing one pin terminal and chip spacer of the electronic module according to the first embodiment, FIG. 2(b) is a vertical cross-sectional view of FIG. 2(a), and FIG. 2(c) is a perspective view showing the appearance of the chip spacer. FIG. 2(b) is a cross-sectional view of the electronic module according to the first embodiment, and FIG. 2(c) is a perspective view showing the appearance of the chip spacer. FIG. 2(c) is a cross-sectional view of the electronic module according to the first embodiment. FIG. 2(b) is a diagram showing a case where a plurality of internal connection terminals that are pin terminals are used. FIG. 2(c) is a cross-sectional view of the electronic module according to the second embodiment. FIG. 2(c) is a diagram showing the cross-sectional structure of the electronic module according to the second embodiment. FIG. 2(c) is a diagram showing an electronic module according to the prior art.

[0013] An electronic module according to the present invention will be described below. The embodiments described below do not limit the scope of the invention. Furthermore, not all of the elements and combinations thereof described in the embodiments are necessarily essential to the present invention.

[0014] First Embodiment An electronic module 100 according to a first embodiment has a generally rectangular parallelepiped shape that is long in the front-to-rear direction and flat in the up-to-down direction, as shown in Fig. 1. The electronic module 100 includes an insulating substrate 112, an electronic element 120, a first terminal 130, a second terminal 140, a third terminal 160, a first connection frame 132B, a second connection frame 142B, a third connection frame 152B, and a sealing resin (not shown).

[0015] The insulating substrate 112 is a DCB (Direct Copper Bonding) ceramic substrate with circuit wiring formed on its upper surface and a heat dissipation metal plate formed on its lower surface (back surface). The two electronic elements 120 are disposed, for example, on circuit wiring formed on one surface of the insulating substrate 112. The insulating substrate 112 may also be a printed circuit board or the like. The insulating substrate 112 is formed in the shape of a rectangular plate, and is preferably disposed in the center of the electronic module 100 in the longitudinal direction, i.e., the front-to-rear direction.

[0016] The two electronic elements 120A, 120B are each disposed on circuit wiring on one surface of the insulating substrate 112. The electronic elements 120A, 120B are configured as semiconductor elements, and may be, for example, power MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), but may also be IGBTs, thyristors, diodes, or other appropriate elements. The electronic elements 120A, 120B have electrodes (not shown) on both surfaces of the semiconductor substrate, with a source electrode and a gate electrode formed on the front surface and a drain electrode (not shown) formed on the back surface.

[0017] In the electronic element 120A, the source electrode is connected to the first terminal 130 via the chip spacer 122, the internal connection terminal 134, and the first connection frame 132B. It is also connected to a pin terminal 172 serving as a sense terminal via a wire, circuit wiring, or the like. The gate electrode is connected to a pin terminal 174 via circuit wiring. The drain electrode is formed on the underside of the semiconductor substrate and electrically connected to the circuit wiring. In the example of FIG. 1 , the internal connection terminal 134 is a pin terminal that is more specifically, a substantially quadrangular than a substantially polygonal shape, and even more specifically, has an arc-shaped shape with outwardly protruding corners, when viewed from above and below.

[0018] In the electronic element 120B, the source electrode is connected to the drain electrode of the front electronic element 120A via a chip spacer (not shown), an internal connection terminal 154, a third connection frame 152B, and circuit wiring, and is also connected to the third terminal 160 via the third connection frame 152B. It is also connected to a pin terminal 172 serving as a sense terminal via a wire, circuit wiring, etc. The gate electrode is connected to a pin terminal 174 via circuit wiring. The drain electrode is formed on the underside of the semiconductor substrate and electrically connected to the second connection frame 142B via circuit wiring. In the example of FIG. 1 , the internal connection terminal 154 is a pin terminal that is more specifically, more substantially rectangular than a substantially polygonal shape when viewed vertically, and more specifically, has an arc-shaped configuration with outwardly protruding corners (hereinafter, the internal connection terminal 154 may be referred to simply as an "approximately polygonal shape" when viewed vertically, such as an approximately rectangular shape or an arc-shaped configuration with outwardly protruding corners).

[0019] The first connection frame 132B and the first terminals 130 are integrally formed from the same plate material 132. That is, the portions of the plate material 132 that are embedded in the sealing resin correspond to the first connection frame 132B. The first connection frame 132B has through holes 133 (see FIG. 3 ) that penetrate the first connection frame 132B in the vertical direction and are electrically connected to the first terminals 130. The through holes 133 are more specifically, more specifically, more generally rectangular than a generally polygonal shape, and more specifically, more specifically, more generally rectangular with arc-like corners that protrude outward when viewed in the vertical direction (hereinafter, the more specifically, more specifically, more generally rectangular than a generally polygonal shape, and more specifically, more specifically, more generally rectangular with arc-like corners that protrude outward when viewed in the vertical direction of the through holes 133, may be simply referred to as a generally polygonal shape). The upper ends of the internal connection terminals 134 are fitted into the through holes 133, and the internal connection terminals 134 connect the first connection frame 132B to electrodes of the electronic elements 120. The shape of the through-hole is not limited to a substantially polygonal shape, but may be a cylindrical shape or the like.

[0020] The internal connection terminals 134 are made of metal and have a generally polygonal shape, and electrically connect the electrodes of the electronic elements 120 to the first connection frame 132B. The internal connection terminals 134 are fixed to and electrically connected to the first connection frame 132B, for example, by press-fitting. The shape of the internal connection terminals is not limited to a generally polygonal shape, and may be cylindrical or the like.

[0021] 2(a) and 2(c), the chip spacer 122 is made of a thin, conductive, flat plate material (a copper plate in this case) and is formed in a generally rectangular shape, more specifically, a generally rectangular shape with arc-like corners that protrude outward, when viewed from above and below (hereinafter, the generally rectangular shape, more specifically, a generally rectangular shape with arc-like corners that protrude outward, more specifically, when viewed from above and below, of the internal connection terminals 154 may be simply referred to as a generally polygonal shape), and is arranged so that the center of the chip spacer 122 coincides with the center of the internal connection terminals 134. The diameter of the chip spacer 122 is set larger than the diameter of the internal connection terminals 134. A recess 113 having an outer diameter larger than the direct outer diameter of the internal connection terminal 134 is formed on the upper surface of the chip spacer 122. The recess 113 is formed in a generally rectangular shape, more specifically, a generally rectangular shape with arc-like corners protruding outward, when viewed vertically. (Hereinafter, the generally rectangular shape, more specifically, a generally rectangular shape with arc-like corners protruding outward, more specifically, a generally rectangular shape, more specifically, a generally polygonal shape, when viewed vertically, of the internal connection terminal 154, may be simply referred to as a generally polygonal shape.) The chip spacer 122 is bonded to the lower surface of the internal connection terminal 134 at the recess 113 via a conductive bonding material (e.g., solder BM2). The lower surface of the chip spacer 122 is bonded to the upper surface of the electronic element 120 (specifically, an electrode not shown) via a conductive bonding material (e.g., solder BM1).

[0022] Furthermore, a convex portion 115 is formed on the underside of the chip spacer 122, and the lower end of the convex portion 115 contacts the electrode of the electronic element 120, thereby maintaining a constant distance between the bottom of the chip spacer 122 and the electronic element 120. This also allows the thickness of the solder BM1 disposed between the chip spacer 122 and the electronic element 120 to be maintained constant. A concave portion 117 corresponding to the convex portion 115 is formed on the upper surface of the chip spacer 122. Note that the convex portion 115 is formed by applying a vertically downward force from above with a pin (not shown) to, for example, four locations in the recess 113 of the chip spacer 122, but it may also be formed by other methods, such as using a mold. Furthermore, the concave portion 117 is formed when the convex portion 115 is formed by applying a vertically downward force with a pin. The external shape of the concave portion 117 corresponds to the shape of the convex portion 115, and its outer diameter and depth vary depending on the shape of the convex portion 115. Furthermore, it is preferable that the positions at which the convex portions 115 and concave portions 117 are formed are outside the outer periphery of the internal connection terminals 134 and inside the outer diameter of the chip spacer 122 .

[0023] Furthermore, it is preferable that the positions of the protrusions 115 and recesses 117 are at least one on each side of the generally polygonal, more specifically generally quadrangular, so that a total of three or more protrusions 115 and recesses 117 are formed. The reason for specifying at least three protrusions 115 and recesses 117 is to avoid affecting the upright position of the chip spacer 122. Furthermore, when the cross-sectional shape of the internal connection terminal 134 is more specifically an approximately square shape than an approximately polygonal shape when viewed in the vertical direction, and even more specifically an approximately square shape with arc-like corners protruding outward (hereinafter, when the internal connection terminal 154 is viewed in the vertical direction, a more specifically an approximately square shape than an approximately polygonal shape, and even more specifically an approximately square shape with arc-like corners protruding outward may be simply referred to as an approximately polygonal shape), it is desirable that the cross-sectional shape of the recess 117 is also more specifically an approximately square shape than an approximately polygonal shape when viewed in the vertical direction, and even more specifically an approximately square shape with arc-like corners protruding outward (hereinafter, when the internal connection terminal 154 is viewed in the vertical direction, a more specifically an approximately square shape than an approximately polygonal shape, and even more specifically an approximately square shape with arc-like corners protruding outward may be simply referred to as an approximately polygonal shape).

[0024] Incidentally, a chip spacer (not shown) is also disposed between the lower surface of the internal connection terminal 154 and the electronic element 120 in the same manner as above, but the structure thereof is the same as above, so a description thereof will be omitted.

[0025] The second connection frame 142B is electrically connected to the second terminals 140. The second connection frame 142B is embedded in the sealing resin. In the electronic module 100, the second connection frame 142B is integrally formed from the same plate material 142 as the second terminals 140. In other words, the portion of the plate material 142 that is embedded in the sealing resin corresponds to the second connection frame 142B.

[0026] The second connection frame 142B has four through holes (reference numerals omitted) that penetrate the second connection frame 142B in the vertical direction. The through holes have a circular shape when viewed in the vertical direction. The upper ends of internal connection electrodes 144 are fitted into each of the four through holes. The second connection frame 142B and electrodes (not shown) of the electronic element 120B are connected by the four internal connection electrodes 144. The internal connection electrodes 144 are fixed to the second connection frame 142B by, for example, press-fitting. The number of the above-mentioned through holes and internal connection electrodes 144 is not limited to four, and can be any number equal to or greater than one, as long as the required power can be passed through.

[0027] The third connection frame 152B is electrically connected to the third terminal 160. The third connection frame 152B may be disposed on the same plane as the first connection frame 132B and the second connection frame 142B.

[0028] The third connection frame 152B has a through-hole (reference numeral omitted) that passes through the third connection frame 152B in the vertical direction. The through-hole has a circular shape when viewed in the vertical direction. The upper end of an internal connection terminal 154 serving as an internal connection electrode is fitted into the through-hole. The internal connection electrode 144 connects the third connection frame 152B to an electrode (not shown) of the electronic element 120. The internal connection terminal 154 is fixed to the third connection frame 152B by, for example, press-fitting.

[0029] As shown in FIG. 1 , the first terminal 130 is disposed at the front of the electronic module 100 in the front-to-rear direction. The first terminal 130 is made of a conductive flat plate material, for example, a plate material 132A formed into a plate shape using a copper plate. The first terminal 130 has a through-hole (reference numeral omitted) that penetrates the first terminal 130 in the vertical direction. When viewed in the vertical direction, the through-hole has, for example, a circular shape. Note that the shape of the through-hole is not limited to a circular shape and may be a polygonal shape such as a hexagon.

[0030] The upper end of the first cap nut 230 is fitted into the through hole. Here, it is preferable that the height of the upper surface of the first cap nut 230 is the same as or lower than the height of the upper surface of the first terminal 130.

[0031] The lower surface of the first terminal 130 and the first cap nut 230 are embedded within the sealing resin, while the upper surface of the first terminal 130 is exposed to the outside of the sealing resin. An external connection member (not shown) is placed on the upper surface of the first terminal 130 exposed from the sealing resin and fixed with a bolt (not shown), thereby making it possible to establish an electrical connection between the first terminal 130 and the external connection member.

[0032] 1 to 3, the second terminal 140 is disposed at the rear of the electronic module 100 in the front-to-rear direction. The second terminal 140 is made of a conductive flat plate material, for example, a plate material 142A formed from a copper plate. The second terminal 140 has a through-hole (reference numeral omitted) that passes through the second terminal 140 in the vertical direction. The through-hole has, for example, a circular shape when viewed in the vertical direction.

[0033] The upper end of the second cap nut 240 is fitted into the through hole. Here, it is preferable that the height of the upper surface of the second cap nut 240 is the same as or lower than the height of the upper surface of the second terminal 140.

[0034] The lower surface of the second terminal 140 and the second cap nut 240 are embedded within the sealing resin, while the upper surface of the second terminal 140 is exposed to the outside of the sealing resin. An external connection member (not shown) is placed on the upper surface of the second terminal 140 exposed from the sealing resin and fixed with a bolt (not shown), thereby making it possible to establish an electrical connection between the second terminal 140 and the external connection member.

[0035] The electronic module 100 may include a third terminal 160. The third terminal 160 is an optional component. As shown in FIG. 1 , the third terminal 160 is formed from a conductive flat plate material, for example, a copper plate. The third terminal 160 is disposed so that the front-to-rear direction is the plate thickness direction, and has an elongated shape with the vertical direction as the longitudinal direction. The third terminal 160 is disposed above the sealing resin, and has a portion exposed from the sealing resin (hereinafter referred to as the "upper portion") and a portion covered by the sealing resin (hereinafter referred to as the "lower portion").

[0036] The upper portion of the third terminal 160 is provided with a through-hole (reference numeral omitted) that penetrates the third terminal 160 in the front-to-rear direction. This allows an external connection member (not shown) to be fixed to the third terminal 160 with a bolt (not shown) and a nut (not shown). Furthermore, one end of a cap nut (not shown) may be fitted into the through-hole. This ensures reliable electrical connection between the third terminal 160 and the external connection member when the external connection member is fixed to the third terminal 160 with a bolt. The lower portion of the third terminal 160 is connected to an electrode (not shown) of the electronic element 120.

[0037] According to the electronic module 100 of the first embodiment, at least one recess having a diameter larger than that of the internal connection terminals is formed on the upper surface of the chip spacer 122, thereby suppressing misalignment between the internal connection terminals 134 and the chip spacer 122 and improving the desired self-alignment effect. Furthermore, when the shape of the chip spacer 122 is increased in accordance with the number of chip electrodes, it is possible to provide an electronic module that suppresses misalignment between the internal connection terminals 134 and the chip spacer 122 and rotation of the chip spacer 122 during solder melting, thereby improving the desired self-alignment effect. Furthermore, according to the electronic module 100 of the first embodiment, the chip spacer 122 is formed with a recess 113 having an outer diameter larger than that of the internal connection terminals 134. This recess 113 prevents the solder BM2 from flowing outward in the radial direction from between the upper surface of the chip spacer 122 and the lower surface of the internal connection terminals 134.

[0038] Furthermore, since the chip spacer 122 is arranged so as to coincide with the center of the internal connection terminal 134, rotational movement of the internal connection terminal 134 can be suppressed when the solder coagulates.

[0039] Furthermore, even if the shape of the chip spacer 122 is increased in accordance with the number of chip electrodes, it is possible to suppress the radial outward flow of solder BM2 from between the upper surface of the chip spacer 122 and the lower surface of the internal connection terminal 134, and the rotational movement of the internal connection terminal 134 when the solder condenses.

[0040] Furthermore, since the cross section of the internal connection terminal 134 is formed in a substantially polygonal shape, rotation of the internal connection terminal 134 can be suppressed.

[0041] (See FIG. 4.) When the internal connection terminal is cylindrical, the rotational movement of the internal connection terminal can be suppressed by using at least two internal connection terminals. The electronic module 100 is provided with at least one internal connection terminal 134.

[0042] Furthermore, since the cross section of the recess 113 is approximately polygonal, the internal connection terminal 134 fits into the recess 113, preventing the solder BM2 from flowing radially outward from between the upper surface of the chip spacer 122 and the lower surface of the internal connection terminal 134, and preventing the internal connection terminal 134 from rotating when the solder condenses.

[0043] Furthermore, since the cross section of the chip spacer 122 is substantially polygonal, the contact area with the electronic element 120 can be increased, and contact resistance can be reduced.

[0044] Furthermore, since at least a portion of the cross section of the internal connection terminal 134 and the recess 113 is formed in the same substantially polygonal shape, rotational movement of the internal connection terminal 134 can be suppressed.

[0045] Second Embodiment An electronic module according to a second embodiment of the present invention will now be described with reference to FIG. 5. This second embodiment is similar to the first embodiment described above except that the recess 117 is not formed, so only the differences will be described and a description of the similar parts will be omitted. As shown in FIG. 5, the chip spacer 126 is molded using a mold to form only the protrusion 115 without the recess 117 as shown in FIG. 2(c). Even in this case where only the protrusion 115 is formed without the recess 117, the chip spacer 126 still has an annular depression 113 formed in it that has an outer diameter larger than the diameter of the internal connection terminal 134.

[0046] Therefore, the recesses 113 in the chip spacer 126, which have an outer diameter larger than the diameter of the internal connection terminals 134, can prevent the solder BM2 from flowing outward in the radial direction from between the upper surface of the chip spacer 122 and the lower surface of the internal connection terminals 134. Furthermore, the protrusions 115 formed on the lower surface of the chip spacer 126 can cause the solder BM1 to self-align toward the axial center of the internal connection terminals 134 when it aggregates.

[0047] It should be noted that the present invention is not limited to the above-described embodiment, and various modifications and applications are possible within the scope of the invention as defined in the claims.

[0048] That is, in the above-described embodiment, the recess 113 having a diameter larger than that of the internal connection terminal 134 is formed on the upper surface of the chip spacer 122, but a plurality of these large-diameter recesses 113 may be formed in accordance with the number of internal connection terminals 134. In other words, the technical effect of the present invention can be achieved as long as at least one recess 113 having a diameter larger than that of the internal connection terminal 134 is formed on the upper surface of the chip spacer 122.

[0049] In the above-described embodiment, the cross section of the internal connection terminal 134 is formed in a substantially polygonal shape, but only a portion of the cross section may be formed in a substantially polygonal shape. In other words, the technical effect of the present invention can be achieved as long as at least a portion of the cross section of the internal connection terminal 134 is formed in a substantially polygonal shape.

[0050] Furthermore, in the above-described embodiment, the cross section of the recess 113 is formed in a substantially polygonal shape, but a portion of the cross section may be formed in a substantially polygonal shape. In other words, the technical effect of the present invention can be achieved as long as at least a portion of the cross section of the recess 113 is formed in a substantially polygonal shape.

[0051] Furthermore, in the above-described embodiment, the chip spacer 122 is formed in a substantially polygonal shape, but only a portion of the chip spacer 122 may be formed in a substantially polygonal shape. In other words, the technical effect of the present invention can be achieved as long as at least a portion of the chip spacer 122 is formed in a substantially polygonal shape.

[0052] DESCRIPTION OF SYMBOLS 100...Electronic module 112...Insulating substrate 113...Depression 115...Protrusion 117...Concave portion 120...Semiconductor element (electronic element) 122...Chip spacer 130...First terminal 132A, 142A, 160A...Flat plate material 134, 154...Internal connection terminal 140...Second terminal 132B, 142B, 152B...Connection frame 160...Third terminal 170...Sealing resin

Claims

1. An electronic module comprising: an electronic element; at least one internal connection terminal electrically connected to the electronic element and having electrical conductivity; and a chip spacer formed between a lower end surface of the internal connection terminal and the electronic element, the chip spacer being bonded to the electronic element via a conductive bonding material, and at least one recess having a larger diameter than the internal connection terminal being formed in an upper surface of the chip spacer.

2. The electronic module according to claim 1, characterized in that at least a portion of the internal connection terminals are formed in a substantially polygonal shape.

3. The electronic module according to claim 1 or 2, characterized in that at least a portion of the recess is substantially polygonal in shape.

4. The electronic module according to claim 3, wherein said internal connection terminals and at least a portion of said recesses are formed in a similar substantially polygonal shape.

5. The electronic module of claim 1, wherein at least a portion of the chip spacer is generally polygonal in shape.

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