JP4884121B2 - Semiconductor device for power control - Google Patents

Description

  The present invention relates to a power control semiconductor device, and more particularly to a power control semiconductor device including a semiconductor element for controlling power and a frame.

As one of the power control semiconductor devices, there is a so-called transfer type power control semiconductor device in which a semiconductor element for controlling power is sealed by injection molding. This type of power control semiconductor device includes a semiconductor element that controls power and a frame in which an electric circuit for driving the semiconductor element is formed. The semiconductor element and the frame are joined via a direct lead which is a separate member from the frame in order to suppress thermal stress acting on the semiconductor device. For example, Patent Documents 1 to 3 are documents that disclose a connection structure between a semiconductor element and an electrode.
JP 05-315490 A JP 2000-236056 A JP 2003-318344 A

  However, the conventional power control semiconductor device has the following problems. As described above, in the transfer type power control semiconductor device, the semiconductor element and the frame are electrically connected to each other through a separate direct lead. Therefore, the inductance tends to increase and the wiring resistance tends to increase due to the influence of the distance between the heat spreader on which the semiconductor element is placed and the frame. Further, such additional direct leads are required as parts, and the reduction of assembly man-hours has been hindered.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a power control semiconductor device capable of reducing inductance and reducing wiring resistance.

  A power control semiconductor device according to the present invention includes a heat spreader, a semiconductor element for controlling power, and a frame. The semiconductor element is disposed on the heat spreader with the first solder interposed. The frame is electrically connected to the semiconductor element, and a predetermined electric circuit for driving the semiconductor element is formed. The frame includes a frame body and a protrusion. The projecting portion is formed integrally with the frame body including a portion thinner than the thickness of the frame body, and is joined to the surface of the semiconductor element by the second solder.

  According to the semiconductor device for power control according to the present invention, the protrusion formed integrally with the frame body is joined to the surface of the semiconductor element. Thereby, compared with the case where the main frame is connected to the surface of the semiconductor element via another member, there is no variation in the distance between the frame body and the semiconductor element due to the mounting accuracy of such another member and the By reducing the interval, the inductance can be reduced. Further, since no additional member is interposed between the frame body and the semiconductor element, the wiring resistance can be reduced. Further, since the protruding portion is formed thinner than the thickness of the frame main body, it becomes easy to absorb the thermal stress, and the connection portion on the surface of the semiconductor element can be prevented from being damaged by the thermal stress.

Embodiment 1
A power control semiconductor device according to the first embodiment of the present invention will be described. As shown in FIGS. 1 and 2, in this power control semiconductor device 1, a semiconductor element 5 for controlling power is joined by solder (first solder) 4 on one main surface of a heat spreader 2. Yes. The other main surface of the heat spreader 2 is covered with an insulating sheet 3.

A frame 7 is electrically connected to the surface of a predetermined region in the semiconductor element 5. The frame 7 includes a frame body 8 and a protruding portion 9. The frame body 8 is formed with a predetermined electric circuit (not shown) for driving the semiconductor element 5. Frame body 8 has a predetermined thickness t _0. The protruding portion 9 protrudes from the frame body 8 toward the semiconductor element 5 side. The protruding portion 9 is formed integrally with the frame 7 by performing the frame 7 for example drawing.

By forming by processing stop projections 9 to frame 7, the thickness t ₁ of protrusion 9 is thinner than the thickness t ₀ of the frame 7. The thickness t ₁ of the protruding portion 9 is desirably substantially the same as the thickness of the semiconductor element 5. For example, when the thickness t ₀ of the frame body 8 is about 0.7 mm, the thickness t ₁ of the protruding portion 9 is about 0.25 mm. The protruding portion 9 is joined to the surface of the semiconductor element 5 by solder (second solder) 6. The height H of the protrusion 9 is about 0.7 mm. In each cross-sectional view including FIG. 2, the vertical direction is shown enlarged to show the structure of the protruding portion 9 in an easily understandable manner.

  In this power control semiconductor device 1, four protruding portions 9 are bonded to the surface of a predetermined region with respect to one semiconductor element 5. The power control semiconductor device 1 according to the embodiment of the present invention is configured as described above.

Next, a power control semiconductor device according to a comparative example will be described. As shown in FIGS. 3 to 5, in the power control semiconductor device 101 according to the comparative example, a semiconductor element 105 for controlling power is joined by solder 104 on one main surface of the heat spreader 102. A main frame 107 in which an electric circuit for driving the semiconductor element 105 is formed is electrically connected to the semiconductor element 105. The main frame 107 Direct lead 110 is mounted, the direct lead 110 is bonded to the surface of the semiconductor element 105 by the solder 106.

  As described above, in the power control semiconductor device 101 according to the comparative example, the semiconductor element 105 and the main frame 107 have a direct lead 110 that is a separate member from the main frame 107 in order to suppress thermal stress acting on the semiconductor element 105. It is electrically connected via. Therefore, for example, due to variations in mounting accuracy when the direct leads 110 are mounted on the main frame 107, the distance between the semiconductor element 105 and the main frame 107 fluctuates, and the inductance tends to increase. Further, the direct lead 110, which is a separate member from the main frame 107, is interposed between the semiconductor element 105 and the wiring resistance tends to increase. Furthermore, an additional part called the direct lead 110 is required, which increases the number of parts and increases the number of assembling steps, which hinders reduction in production cost.

  On the other hand, in the power control semiconductor device 1 according to the first embodiment described above, the protruding portion 9 formed integrally with the frame body 8 is joined to the surface of the semiconductor element 5. As a result, compared with the power control semiconductor device 101 according to the comparative example in which the main frame 107 is connected to the surface of the semiconductor element 105 via the direct lead 110 which is a member different from the main frame 107, Variations in the distance between the frame body 8 and the semiconductor element 5 due to the mounting accuracy can be eliminated and the distance can be narrowed to reduce inductance. Further, since no additional member is interposed between the frame body 8 and the semiconductor element 5, the wiring resistance can be reduced.

  Here, the inductance will be briefly described. When the power control semiconductor device 1 is operating, the semiconductor element 5 is repeatedly turned on and off to perform a switching operation, and the direction of current in the circuit always changes. During the switching, a surge voltage is generated as shown in FIG. It is important to suppress the surge voltage 20 as the performance of the power control semiconductor device 1.

  The surge voltage V and the inductance L in the power control semiconductor device 1 have a relationship of V = L · di / dt, and the surge voltage is reduced by reducing the inductance L in the power control semiconductor device 1. Is possible. The relationship between the distance h between the frame 7 and the heat spreader 2 and the inductance in the power control semiconductor device 1 is as shown in FIG. 7, and the inductance tends to decrease as the distance h decreases.

  As shown in FIG. 8, the current 30 flowing through the power control semiconductor device 1 is configured such that the direction of the current 30 flowing through the frame 7 and the direction of the current 30 flowing through the heat spreader 2 are opposite to each other. . Since the directions of the currents 30 are opposite to each other, the magnetic flux generated by the current 30 flowing through the frame 7 and the magnetic flux generated by the current 30 flowing through the heat spreader 2 cancel each other, thereby reducing the inductance.

  In the power control semiconductor device 1, the distance h between the frame 7 and the heat spreader 2 can be further reduced by further reducing the distance between the frame 7 and the semiconductor element 5 as described above. Thereby, the magnetic flux generated by the current flowing through the both cancels out more effectively, and the inductance can be further reduced.

Further, in the power control semiconductor device 1 described above, the protruding portion 9 is formed to be thinner (t ₁ ) than the thickness t ₀ of the frame body 8 by subjecting the frame body 8 to a drawing process, thereby causing thermal stress. It becomes easy to absorb and it can suppress that the connection part (electrode member) on the surface of the semiconductor element 5 is damaged by thermal stress. This thermal stress is caused by a difference in linear expansion coefficient between the frame 7 made of, for example, copper and the semiconductor element 5 mainly composed of silicon. If the thickness of the protruding portion 9 of the frame 7 is thick, the linear expansion coefficient is large, and the difference in linear expansion coefficient with the semiconductor element 5 having a relatively small linear expansion coefficient is large, so that thermal stress (strain) is increased. On the other hand, when the thickness of the protruding portion 9 is reduced, the linear expansion coefficient is reduced, approaching the value of the linear expansion coefficient of the semiconductor element 5, and thermal stress can be reduced.

  In the power control semiconductor device 1 described above, the additional direct lead 110 is not necessary as compared with the power control semiconductor device 101 according to the comparative example. Thereby, it is possible to reduce the number of parts and assembly man-hours of the power control semiconductor device 1, thereby reducing the production cost.

Embodiment 2
Next, a power control semiconductor device according to the second embodiment will be described. As shown in FIGS. 9 and 10, in this power control semiconductor device 1, an opening 10 is provided in a protrusion 9 that is integrally formed by drawing the frame body 8, and the protrusion 9 The tip end portion 9a is a release end. The open end portion 9 a is joined to the surface of the semiconductor element 5 by solder 6. Since other configurations are the same as those of the power control semiconductor device 1 shown in FIGS. 1 and 2, the same members are denoted by the same reference numerals, and the description thereof is omitted.

  In the power control semiconductor device 1 described above, the following effects are obtained in addition to the effects described in the first embodiment. That is, by providing the opening portion 10 in the projecting portion 9 of the frame 7, the tip end portion 9 a is an open end, and the tip end portion 9 a that is the open end is joined to the surface of the semiconductor element 5 by the solder 6. Strain (thermal stress) acting on the joint portion between the tip portion 9a and the solder 6 can be easily absorbed. As a result, the reliability of the power control semiconductor device 1 can be improved and the lifetime can be extended. The opening shape is not particularly limited as long as the opening portion 10 has an aspect in which the distal end portion 9 a of the protruding portion 9 is an open end with respect to the frame body 8.

Modified Example A modified example of the power control semiconductor device in which an opening is provided at the tip of the protruding part will be described. As shown in FIGS. 11 and 12, in the power control semiconductor device 1 according to the modification, an opening 10 having a substantially circular plane (upper surface) shape is formed in the tip portion 9 a of the protruding portion 9. The protruding portion 9 of the frame 7 is joined to the surface of the semiconductor element 5 in such a manner that the solder 6 rises from the opening 10 by the solder 6. Since other configurations are the same as those of the power control semiconductor device 1 shown in FIGS. 1 and 2, the same members are denoted by the same reference numerals, and the description thereof is omitted.

  In the power control semiconductor device 1 according to this modification, the area in which the frame 7 having a relatively large linear expansion coefficient and the semiconductor element 5 having a relatively small linear expansion coefficient are in direct contact with each other can be reduced. Thermal stress (strain) can be reduced.

Reference Example Next, a power control semiconductor device according to a reference example related to the present invention will be described. As shown in FIGS. 13 and 14, in the power control semiconductor device 1, the tip end portion 9 a of the protruding portion 9 has a tapered shape that becomes gradually narrower toward the tip end. Further, the protruding portion 9 is provided with a step portion 11 between the frame main body 8 and the tip end portion 9a so as to become thinner stepwise from the frame main body 8 toward the tip end portion 9a. By the step 11, for example, the width W ₁ (about 15 mm) of the protrusion 9 is reduced to the width W ₂ (about 5 mm). Since other configurations are the same as those of the power control semiconductor device 1 shown in FIGS. 1 and 2, the same members are denoted by the same reference numerals, and the description thereof is omitted.

  In the power control semiconductor device 1 described above, the following effects are obtained in addition to the effects described in the first embodiment. That is, the tip end portion 9a of the protruding portion 9 has a tapered shape that gradually becomes thinner toward the tip end. As a result, as shown in FIG. 15, a distance h (about 1 mm) from the position where the tip portion 9a contacts the surface of the semiconductor element 5 to the peripheral portion of the semiconductor element 5 is secured, and the tip portion 9a and the semiconductor element 5 are secured. Can be positioned over the region extending from the contacted portion to the peripheral portion of the semiconductor element 5. As a result, the solder 6 positioned over a wider area in the vicinity of the surface of the semiconductor element 5 can suppress cracks from spreading on the outer peripheral portion of the solder 6 due to thermal stress due to a temperature cycle.

Further, by providing the protruding portion 8 with the stepped portion 11, the distance (h) between the frame body 8 and the heat spreader 2 can be changed only by changing the position (h ₁ ) of the stepped portion 11 without changing the drawing depth. ₂ ) can be easily changed. In addition to the power control semiconductor device 1 according to the present embodiment, the step portion 11 can be applied to a power control semiconductor device according to another embodiment.

Embodiment 3
Next, a power control semiconductor device according to the third embodiment will be described. As shown in FIGS. 16 and 17, in the power control semiconductor device 1, a plurality of projecting portions 9 joined to one semiconductor element 5 are formed in the frame body 8. On the other hand, a plurality of regions divided by the guard ring 12 and the slit 13 are formed in one semiconductor element 5. The plurality of protrusions 9 are respectively joined to regions corresponding to the divided regions in the semiconductor element 5. Since other configurations are the same as those of the power control semiconductor device 1 shown in FIGS. 1 and 2, the same members are denoted by the same reference numerals, and the description thereof is omitted.

  In the power control semiconductor device 1 described above, the following effects are obtained in addition to the effects described in the first embodiment. That is, by bringing the plurality of protruding portions 9 into contact with one semiconductor element 5, the bonding area per protruding portion 9 is reduced, and thermal stress acting on the semiconductor element 5 can be reduced. Further, when the semiconductor element 5 is divided by the guard ring 12 and the slit 13, a plurality of projecting portions corresponding to the divided regions are formed on the frame body 8 by drawing, so that The protrusion can be easily joined to each of the divided regions in the semiconductor element.

Embodiment 4
Next, a power control semiconductor device according to the fourth embodiment will be described. As shown in FIGS. 18 and 19, in this power control semiconductor device 1, almost the entire protrusion 9 is formed with a uniform thickness that is thinner than the thickness of the frame body 8. As the size of the protruding portion 9, for example, the width W is about 5 mm and the height H is about 0.7 mm. Since other configurations are the same as those of the power control semiconductor device 1 shown in FIGS. 1 and 2, the same members are denoted by the same reference numerals, and the description thereof is omitted.

  In the power control semiconductor device 1 described above, the following effects are obtained in addition to the effects described in the first embodiment. That is, since the protruding portion 9 is formed substantially uniformly with a thickness thinner than the thickness of the frame body 8, the thermal stress acting on the semiconductor element 5 can be more effectively reduced.

Embodiment 5
Next, a power control semiconductor device according to the fifth embodiment will be described. As shown in FIGS. 20 and 21, in the power control semiconductor device 1, the protruding portion 9 connects the flat plate portion 9 c joined to the semiconductor element 5, and the flat plate portion 9 c and the frame body 8. And a side plate portion 9d. The flat plate portion 9c is formed to have substantially the same thickness as the thickness (t ₀ ) of the frame body 8, and the side plate portion 9d is formed thinner than the thickness of the frame body 8 (thickness t ₁ ).

The flat plate portion 9 c is not intended to be a complete flat surface, and may be formed so as to ensure a larger bonding surface with respect to the semiconductor element 5. As the size of the protruding portion 9, for example, the width W ₁ is about 15 mm, the width W ₂ is about 5 mm, is height H is about 0.7 mm. Since other configurations are the same as those of the power control semiconductor device 1 shown in FIGS. 1 and 2, the same members are denoted by the same reference numerals, and the description thereof is omitted.

In the power control semiconductor device 1 described above, the following effects are obtained in addition to the effects described in the first embodiment. That is, heat dissipation can be effectively performed by increasing the bonding area of the protruding portion 9 to the semiconductor element 5. Further, since the thickness of the side plate portion 9d is thinner than the frame body 8 (thickness t ₁ ), the thermal stress (strain) acting on the junction between the flat plate portion 9c and the semiconductor element 5 is absorbed. In addition, the reliability of the power control semiconductor device 1 can be improved and the lifetime thereof can be extended.

  In each of the above-described embodiments, the case where the projecting portion 9 is formed integrally with the frame main body 8 by drawing the frame main body 8 has been described as an example. However, the protrusion 9 is integrated with the frame main body 7a. As long as it is formed and has a portion formed thinner than the frame body 8, it is not limited to drawing. Moreover, the value of the dimension quoted in each embodiment is an example, Comprising: It is not limited to these dimensions.

  The embodiment disclosed this time is merely an example, and the present invention is not limited to this. The present invention is defined by the terms of the claims, rather than the scope described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a top view of a power control semiconductor device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along a cross-sectional line II-II shown in FIG. 1 in the same embodiment. It is a top view of the semiconductor device for electric power control which concerns on a comparative example. FIG. 4 is a sectional view taken along a sectional line IV-IV shown in FIG. 3. FIG. 4 is a side view of the power control semiconductor device shown in FIG. 3. In the same embodiment, it is a graph which shows the time change of the voltage at the time of the switching operation | movement for demonstrating a surge voltage. In the same embodiment, it is a graph which shows the dependence of the distance between the flame | frame of an inductance, and a heat spreader. In the same embodiment, it is a figure which shows the electric current which flows through the semiconductor device for electric power control. It is a top view of the semiconductor device for electric power control which concerns on Embodiment 2 of this invention. FIG. 10 is a cross-sectional view taken along a cross-sectional line XX shown in FIG. 9 in the same embodiment. In the same embodiment, it is a top view of the semiconductor device for electric power control concerning a modification. FIG. 12 is a cross sectional view taken along a cross sectional line XII-XII shown in FIG. 11 in the same embodiment. It is a top view of the semiconductor device for electric power control which concerns on the reference example relevant to this invention. FIG. 14 is a cross-sectional view taken along a cross-sectional line XIV-XIV shown in FIG. 13 in the reference example . FIG. 15 is a partial enlarged cross-sectional view showing an enlarged view of a dotted frame shown in FIG. 14 in the reference example . It is a top view of the semiconductor device for electric power control which concerns on Embodiment 3 of this invention. FIG. 17 is a cross-sectional view taken along a cross-sectional line XVII-XVII shown in FIG. 16 in the same embodiment. It is a top view of the semiconductor device for electric power control which concerns on Embodiment 4 of this invention. FIG. 19 is a cross-sectional view taken along a cross-sectional line XIX-XIX shown in FIG. 18 in the same embodiment. It is a top view of the semiconductor device for electric power control which concerns on Embodiment 5 of this invention. FIG. 21 is a cross sectional view taken along a cross sectional line XXI-XXI shown in FIG. 20 in the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Power control semiconductor device, 2 Heat spreader, 3 Insulating sheet, 4,6 Solder, 5 Semiconductor element, 7 Frame, 8 Frame main body, 9 Protruding part, 10 Opening part, 11 Step part, 12 Guard ring, 13 Slit.

Claims (7)

A heat spreader,
A semiconductor element for controlling electric power, disposed on the heat spreader with a first solder interposed;
A frame electrically connected to the semiconductor element and formed with a predetermined electric circuit for driving the semiconductor element;
The frame is
The frame body,
Including a portion that is thinner than the thickness of the frame body, and is integrally formed with the frame body, and includes a protrusion that is joined to the surface of the semiconductor element by a second solder ,
A power control semiconductor device, wherein an opening is provided at a tip of the protrusion . The power control semiconductor device according to claim 1, wherein the opening is formed in such a manner that a tip end portion of the protrusion is an open end . Wherein the frame, the predetermined region to be bonded to the surface of the semiconductor element to, as the projecting portion joined by a plurality of protrusions, the power control semiconductor device according to claim 1 or 2. The surface of the semiconductor element is divided into a plurality of regions,
The power control semiconductor device according to claim 3 , wherein the plurality of protrusions are joined to the corresponding divided regions . A heat spreader,
A semiconductor element for controlling electric power, disposed on the heat spreader with a first solder interposed;
A frame electrically connected to the semiconductor element and formed with a predetermined electric circuit for driving the semiconductor element;
Have
The frame is
The frame body,
A protrusion formed integrally with the frame body including a portion thinner than the thickness of the frame body and joined to the surface of the semiconductor element by a second solder;
With
The protrusion is a semiconductor device for power control , wherein the protrusion is uniformly formed over the entire protrusion with a thickness smaller than the thickness of the frame body . A heat spreader,
A semiconductor element for controlling electric power, disposed on the heat spreader with a first solder interposed;
A frame electrically connected to the semiconductor element and formed with a predetermined electric circuit for driving the semiconductor element;
Have
The frame is
The frame body,
A protrusion formed integrally with the frame body including a portion thinner than the thickness of the frame body and joined to the surface of the semiconductor element by a second solder;
With
The protrusion is
A flat plate portion bonded to the semiconductor element;
A side plate portion connecting the flat plate portion and the frame body;
Including
The power control semiconductor device , wherein the side plate portion is thinner than the flat plate portion . Wherein the projecting portion, the step portion so that thinner stepwise toward the side of the semiconductor element from the frame body is provided, the power control semiconductor device according to any one of claims 1-6.

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