JP2024159058A - Electronic Module - Google Patents

Abstract

An electronic module is provided that can suppress misalignment between an internal connection terminal and a chip spacer and improve a desired self-alignment effect.
[Solution] The electronic module 100 comprises an electronic element 120, an internal connection terminal 134 electrically connected to the electronic element 120 and having conductivity, and a chip spacer 122 formed between the lower end surface of the internal connection terminal 134 and the electronic element 120. The chip spacer 122 is joined to the electronic element 120 via a conductive bonding material BM1, and a recess 113 having a larger diameter than the internal connection terminal 134 is formed on the upper surface of the chip spacer 122.
[Selected figure] Figure 3

Description

The present invention relates to an electronic module.

Conventionally, electronic modules are known that include an electronic element (semiconductor element, semiconductor chip) and an internal connection terminal that connects an electrode of the electronic element to a wiring pattern on a substrate. Meanwhile, electronic modules are known that include an electronic element, a substrate on which the electronic element is mounted, pin terminals as internal connection terminals connected to the wiring pattern on the substrate, and a lead frame that supports the pin terminals and electrically connects the electrodes of the electronic element to the pin terminals (see Patent Document 1 below). Some electronic modules of this type have internal connection terminals that are connected to electrodes of the electronic element rather than to the wiring pattern. One such electronic module is one in which the electronic element is connected to the internal connection terminal via a chip spacer to relieve stress.

Incidentally, there is also known an electronic module in which an electronic element 320 is bonded to an insulating substrate 312 via solder BM 30 as shown in FIG. 6, and a chip spacer 318 is bonded to the lower end side of an internal connection terminal 334 via solder BM 20, the internal connection terminal 334 being inserted into a through hole (not shown) formed in a lead frame (not shown).

Patent No. 6850938

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

The present invention has been made in consideration of the above problems, and aims to provide an electronic module that suppresses misalignment between the internal connection terminals and the chip spacer, thereby improving the desired self-alignment effect.

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

The electronic module of the present invention has a recess with a larger diameter than the terminal formed in the outer periphery of the upper surface of the chip spacer, in an area corresponding to the outer periphery of the terminal, making it possible to provide an electronic module that suppresses misalignment between the internal connection terminal and the chip spacer and improves the desired self-alignment effect.

1 is a perspective view showing an external appearance of an electronic module 100 according to a first embodiment. 2A is a plan view showing one pin terminal and a chip spacer of an electronic module according to the first embodiment, FIG. 2B is a vertical cross-sectional view of FIG. 2A, and FIG. 2C is a perspective view showing the appearance of the chip spacer. 1 is a diagram showing a cross-sectional structure of an electronic module 100 according to a first embodiment. Fig. 4(a) is a diagram showing the state of the pin terminal and the chip spacer when the pin terminal rotates when the pin terminal and the chip spacer are square-shaped, and Fig. 4(b) is a diagram showing the state of the pin terminal and the chip spacer when the pin terminal rotates when the pin terminal and the chip spacer are disk-shaped. FIG. 11 is a diagram showing a cross-sectional structure of an electronic module 100 according to a second embodiment. FIG. 1 is a diagram for explaining an electronic module according to a conventional technique.

The electronic module according to the present invention will be described below. 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 present invention.

(First embodiment)
The electronic module 100 according to the first embodiment has a generally rectangular parallelepiped shape that is long in the front-rear direction and flat in the up-down direction, as shown in Fig. 1. The electronic module 100 includes an insulating substrate 112, electronic elements 120A and 120B, 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).

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

The two electronic elements 120A, 120B are each disposed on the circuit wiring on one side 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 suitable elements. The electronic elements 120A, 120B have electrodes (not shown) on both sides 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.

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 as a sense terminal via a wire or circuit wiring. The gate electrode is connected to a pin terminal 174 via the circuit wiring. The drain electrode is formed on the underside of the semiconductor substrate and is electrically connected to the circuit wiring. In the example of FIG. 1, the internal connection terminal 134 is a pin terminal with a circular cross section.

In the electronic element 120B, the source electrode is connected to the drain electrode of the electronic element 120A on the front side 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 182 as a sense terminal via a wire, circuit wiring, etc. The gate electrode is connected to a pin terminal 184 via circuit wiring. The drain electrode is formed on the lower surface side of the semiconductor substrate and is 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 with a circular cross section.

The first connection frame 132B and the first terminal 130 are integrally formed from the same plate material 132. That is, the portion of the plate material 132 that is embedded in the sealing resin corresponds to the first connection frame 132B. The first connection frame 132B has a through hole 133 (see FIG. 3) that penetrates the first connection frame 132B in the vertical direction, and is electrically connected to the first terminal 130. The through hole 133 has a circular shape when viewed in the vertical direction. The upper end of the internal connection terminal 134 is fitted into the through hole 133, and the first connection frame 132B and the electrode of the electronic element 120A are connected by the internal connection terminal 134. The shape of the through hole is not limited to a circular shape, and may be a polygonal shape such as a hexagon.

The internal connection terminal 134 is made of a cylindrical metal, electrically connects the electrode of the electronic element 120A to the first connection frame 132B, and is fixed to the first connection frame 132B by, for example, press-fitting.

As shown in FIG. 2(a) and FIG. 2(c), the chip spacer 122 is formed in a disk shape using a thin conductive flat plate material (copper plate in this case) and is arranged concentrically with the internal connection terminal 134. The diameter of the chip spacer 122 is set to be larger than the diameter of the internal connection terminal 134. An annular recess 113 having an outer diameter larger than the diameter of the internal connection terminal 134 is formed on the upper surface of the chip spacer 122, and 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 120A (specifically, an electrode not shown) via a conductive bonding material (e.g., solder BM1). In the following description, when there is no need to distinguish between them, the electronic element will be referred to as 120 for convenience of explanation.

In addition, a convex portion 115 is formed on the lower surface of the chip spacer 122, and the lower end of the convex portion 115 contacts the electrode of the electronic element 120, so that the distance between the bottom of the chip spacer 122 and the electronic element 120 can be kept constant. The solder thickness of the solder BM1 placed between the chip spacer 122 and the electronic element 120 can be kept constant. A concave portion 117 corresponding to this convex portion 115 is formed on the upper surface of the chip spacer 122. Note that this convex portion 115 is formed by applying force vertically downward from above with a pin (not shown) to, for example, four places in the depression 113 of the chip spacer 122, but it may be formed by other methods, for example, using a mold. In addition, the concave portion 117 is formed when the convex portion 115 is formed by applying force vertically downward with a pin, and the external shape of the concave portion 117 corresponds to the shape of the convex portion 115, and its outer diameter and depth change according to the shape of the convex portion 115. In addition, it is preferable that the positions of the projections 115 and recesses 117 are formed outside the outer periphery of the internal connection terminal 134 and inside the outer diameter of the chip spacer 122, with at least three projections 115 and recesses 117. The reason for having at least three projections 115 and recesses 117 is to avoid affecting the upright position of the chip spacer 122.

Note that a chip spacer (not shown) is also disposed between the underside of the internal connection terminal 154 and the electronic element 120, as described above, but as its structure is the same as described above, its description is omitted.

The second connection frame 142B is electrically connected to the second terminal 140. The second connection frame 142B is embedded inside 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 terminal 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.

The second connection frame 142B has four through holes (reference numbers 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 the 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 as long as it is possible to pass the necessary power, and can be any number greater than or equal to one.

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.

The third connection frame 152B has a through hole (reference number 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 third connection frame 152B and an electrode (not shown) of the electronic element 120B are connected by the internal connection electrode 144. The internal connection terminal 154 is fixed to the third connection frame 152B by, for example, press fitting.

As shown in FIG. 1, the first terminal 130 is disposed at the front in the front-rear direction of the electronic module 100. The first terminal 130 is composed of a conductive flat plate material, for example, a plate material 132A formed into a plate shape from a copper plate. The first terminal 130 has a through hole (reference number omitted) that penetrates the first terminal 130 in the up-down direction. When viewed in the up-down 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 polygon such as a hexagon.

The upper end of the first cap nut 230 fits 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 the height of the upper surface of the first terminal 130 or lower than the height of the upper surface of the first terminal 130.

The lower surface of the first terminal 130 and the first cap nut 230 are embedded inside the sealing resin. Meanwhile, 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), so that an electrical connection can be made between the first terminal 130 and the external connection member.

As shown in Figs. 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 composed of a conductive flat plate material, for example, plate material 142A formed from a copper plate. The second terminal 140 has a through hole (reference number omitted) that passes through the second terminal 140 in the up-down direction. When viewed in the up-down direction, the through hole has, for example, a circular shape.

The upper end of the second cap nut 240 fits 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 the height of the upper surface of the second terminal 140 or lower than the height of the upper surface of the second terminal 140.

The lower surface of the second terminal 140 and the second cap nut 240 are embedded inside the sealing resin. Meanwhile, the upper surface of the second terminal 140 is exposed to the outside of the sealing resin. By placing an external connection member (not shown) on the upper surface of the second terminal 140 exposed from the sealing resin and fixing it with a bolt (not shown), an electrical connection can be made between the second terminal 140 and the external connection member.

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 of 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").

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-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 that when the external connection member is fixed to the third terminal 160 with a bolt, electrical connection between the third terminal 160 and the external connection member can be ensured. The lower portion of the third terminal 160 is connected to electrodes (not shown) of the electronic elements 120A and 120B.

[Effects of the first embodiment]
According to the electronic module 100 of the first embodiment, a ring-shaped recess 113 having an outer diameter larger than the diameter of the internal connection terminal 134 is formed in the chip spacer 122, and this recess 113 can suppress 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.

In addition, the chip spacer 122 is formed in a disk shape and is arranged concentrically with the internal connection terminal 134 (see FIG. 4(b)). For example, when a square-shaped chip spacer 127 is arranged on the upper surface of the electronic element 120 and on the lower surface of a square-shaped internal connection terminal 234, contact with the surrounding electronic components 128 due to the rotational movement of the internal connection terminal 234 during solder condensation can be avoided (see FIG. 4(a)).

Furthermore, a convex portion 115 is formed on the underside of the chip spacer 122, which allows the self-alignment of the solder BM1 during aggregation to occur toward the axis of the internal connection terminal 134.

Furthermore, a recess 117 is formed on the upper surface of the chip spacer 122, which 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 terminal 134.

Second Embodiment
An electronic module according to a second embodiment of the present invention will be described below 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 the description of the similar parts will be omitted. As shown in FIG. 5, the chip spacer 126 is formed by injection molding using a mold, with only the protrusion 115 formed 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 has an annular recess 113 having an outer diameter larger than the diameter of the internal connection terminal 134.

Therefore, the recess 113 in the chip spacer 126, which has an outer diameter larger than the diameter of the internal connection terminal 134, can suppress 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 terminal 134. Furthermore, since the lower surface of the chip spacer 126 is formed with the protrusion 115, the protrusion 115 can cause the solder BM1 to self-align toward the axis of the internal connection terminal 134 when it aggregates.

100...electronic module, 112...insulating substrate, 113...dent, 115...projection, 117...recess, 120 (120A, 120B)...electronic element, 122, 126...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 (4)

An electronic element;
an internal connection terminal electrically connected to the electronic element and having electrical conductivity;
a chip spacer formed between a lower end surface of the internal connection terminal and the electronic element, the chip spacer being joined to the electronic element via a conductive bonding material, and a recess having a diameter larger than that of the internal connection terminal being formed on an upper surface of the chip spacer;
1. An electronic module comprising: The internal connection terminal has a cylindrical shape, and the chip spacer has a disk shape.
2. The electronic module of claim 1. A convex portion is formed on the lower surface of the chip spacer.
2. The electronic module of claim 1. A recess is formed on the upper surface of the chip spacer.
2. The electronic module of claim 1.

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