JP6043238B2 - Semiconductor module - Google Patents

Description

  The technology disclosed in this specification relates to a pressure-contact type semiconductor module in which a semiconductor element and a wiring layer are pressure-fixed.

  As disclosed in Patent Documents 1 to 4, a pressure contact type semiconductor module in which a semiconductor element and a wiring layer are pressure contact fixed has been developed. In such a pressure contact type semiconductor module, since the semiconductor element and the wiring layer are not fixed by solder or the like, the semiconductor element and the wiring layer are not constrained in a direction parallel to the contact surface between them. For this reason, even if a thermal expansion difference occurs between the semiconductor element and the wiring layer due to the influence of heat generated when the semiconductor element operates, due to the effect of slipping in the direction parallel to the contact surface between the semiconductor element and the wiring layer, The stress applied to the semiconductor element and the wiring layer is relaxed.

Japanese Patent Laid-Open No. 5-21259 JP-A-7-99284 Japanese Patent Laying-Open No. 2005-101489 JP 2012-119651 A

  The semiconductor element has an element part and a terminal part. The element portion is provided with a gate structure and is a portion through which a current flows. The termination portion is provided around the element portion and is a portion for improving the lateral breakdown voltage.

  The heat generated when the semiconductor element operates is greater at the element portion than at the termination portion. For this reason, the temperature of the semiconductor element is high at the element part and low at the terminal part. When such a temperature distribution is formed, the element portion thermally expands more than the terminal portion, so that the semiconductor element tends to be deformed to be curved. However, in the pressure contact type semiconductor module, since the pressure contact direction of the semiconductor element is constrained by the wiring layer, the bending deformation is hindered and a large stress is applied.

  In this specification, it aims at providing the technique which relieve | moderates the stress resulting from temperature distribution when a semiconductor element operate | moves.

  The technology disclosed in this specification is embodied in a pressure-contact type semiconductor module in which a semiconductor element and a wiring layer are pressure-fixed. The semiconductor module is provided between the semiconductor element and the wiring layer, and includes a plurality of elastic mechanisms arranged in a plane orthogonal to the pressure contact direction. The elastic mechanism includes a conductive contact body that contacts the semiconductor element and an elastic body that biases the contact body toward the semiconductor element. The semiconductor element and the wiring layer are configured to be electrically connectable via a contact body.

  When the semiconductor element operates to form a temperature distribution, the semiconductor element tends to be deformed so as to bend. In the semiconductor module, the bending deformation of the semiconductor element can be allowed by compressing the elastic body of the elastic mechanism. For this reason, the stress added to a semiconductor element is relieved.

FIG. 1 schematically shows a cross-sectional view of an essential part of one embodiment of the semiconductor module of the first example. FIG. 2 schematically shows an enlarged cross-sectional view of the main part of the elastic mechanism part of the first embodiment. FIG. 3 is a diagram for explaining the effect of the elastic mechanism portion of the first embodiment. FIG. 4 schematically shows a cross-sectional view of one embodiment of the elastic mechanism of the first example. FIG. 5 schematically shows a cross-sectional view of one embodiment of the elastic mechanism of the first example. FIG. 6 is a schematic cross-sectional view of a main part of one embodiment of the semiconductor module of the second example. FIG. 7A schematically shows a cross-sectional view of one embodiment of the elastic mechanism of the second example. FIG. 7B schematically shows a cross-sectional view of one embodiment of the elastic mechanism of the second example.

The technical features disclosed in this specification will be summarized below. The items described below have technical usefulness independently.
(Feature 1) The semiconductor module disclosed in this specification is a pressure contact type in which a semiconductor element and a wiring layer are pressure contact fixed. The semiconductor module may be provided between the semiconductor element and the wiring layer, and may include a plurality of elastic mechanisms arranged in a plane orthogonal to the pressure contact direction. The elastic mechanism may include a conductive contact body that contacts the semiconductor element and an elastic body that biases the contact body toward the semiconductor element. The semiconductor element and the wiring layer may be configured to be electrically connectable via a contact body. Here, the material of the contact body is preferably a material having low electrical resistance and high heat conduction, and is preferably a metal. In one example, the material of the contact body may be copper, aluminum, graphite, and a composite material thereof. The form and material of the elastic body are not particularly limited. Various elastic bodies having a restoring force after compression deformation can be used.
(Feature 2) The elastic mechanism accommodates the contact body and the elastic body, and may further include a conductive casing that contacts the wiring layer. The contact body may be accommodated in the housing so as to be slidable with respect to the housing. The semiconductor element and the wiring layer may be configured to be electrically connectable via a contact body and a housing. Here, the contact body may slide while being in contact with the inner wall of the housing, and the sliding body may be slid using a sliding mechanism (such as a guide mechanism that allows electrical connection between the contact body and the housing). You may move.
(Characteristic 3) The housing may have a drop prevention portion that prevents the contact body from falling off. Various forms can be employed for the slip-off prevention unit. In one example, the drop prevention part may be configured such that a part of the contact body protrudes into a groove formed in a part of the inner wall of the housing. Further, the drop prevention unit may be configured by an elastic body that urges the contact body from the lateral direction.

  Embodiments will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected about the component which is common in each Example.

  As shown in FIG. 1, the pressure contact type semiconductor module 1 includes a cooler 2, an insulating substrate 3, a semiconductor element 4, an elastic mechanism portion 5, and a wiring layer 6. The cooler 2 and the wiring layer 6 are coupled by a fastener (not shown) (in the example, a nut and a bolt), and the insulating substrate 3, the semiconductor element 4, and the elastic mechanism portion 5 are pressed and fixed in the pressing direction (up and down direction in the drawing). doing.

  The cooler 2 is formed with a flow path for circulating a refrigerant, and heat generated in the semiconductor element 4 is radiated to the outside through the refrigerant. The material of the cooler 11 is aluminum in one example.

  The insulating substrate 3 has an upper metal layer 3a, an insulating layer 3b, and a lower metal layer 3c. The upper metal layer 3a is electrically connected to the back electrode of the semiconductor element 4 and is used as a wiring layer. The insulating layer 3b electrically insulates the semiconductor element 4 and the cooler 2 from each other. The lower metal layer 3c is joined to the cooler 2 via a brazing material or grease. In one example, the material of the upper metal layer 3a and the lower metal layer 3c is aluminum. For example, the material of the insulating layer 3b is aluminum nitride.

  For example, the semiconductor element 4 is a vertical IGBT (Insulated Gate Bipolar Transistor). The collector electrode, which is the back electrode of the semiconductor element 4, is electrically connected to the upper metal layer 3 a of the insulating substrate 3, and the emitter electrode, which is the front electrode, is electrically connected to the wiring layer 6 via the elastic mechanism portion 5. Has been.

  As shown in FIG. 2, the elastic mechanism portion 5 is provided between the wiring layer 6 and the semiconductor element 4 and includes a plurality of elastic mechanisms 10 arranged in a plane orthogonal to the pressure contact direction. . The number of the elastic mechanisms 10 may be as long as it can follow the curved deformation of the semiconductor element 4 as will be described later. For example, 5 × 5 elastic mechanisms 10 are used for a semiconductor element 4 of 10 mm × 10 mm. Each of the elastic mechanisms 10 houses a conductive contact body 12 that contacts the semiconductor element 4, an elastic body 14 that biases the contact body 12 toward the semiconductor element 4, and the contact body 12 and the elastic body 14. A conductive housing 16 is provided.

  In one example, the contact body 12 has a substantially cylindrical shape, and one end is in contact with the semiconductor element 4 and the other end is in contact with the elastic body 14. The end of the contact body 12 on the side in contact with the semiconductor element 4 is formed of a curved surface, and the contact body 12 and the semiconductor element 4 are in point contact. The contact body 12 is in contact with the inner wall of the housing 16, and can slide along the press-contact direction with respect to the housing 16 in a state of being in contact with the housing 16. For example, copper is used as the material of the contact body 12. The contact body 12 is accommodated in the housing 16 after the housing 16 is bonded to the wiring layer 6.

  The elastic body 14 is an insulating resin spring, for example, and has one end in contact with the contact body 12 and the other end in contact with the wiring layer 6. The elastic body 14 biases the contact body 12 toward the semiconductor element 4. The elastic body 14 is accommodated in the housing 16 in a state where a predetermined compressive load is applied after the housing 16 is joined to the wiring layer 6.

  The housing 16 has a cylindrical shape as an example, and has an inner wall surface corresponding to the contact body 12. One end of the housing 16 is joined to the wiring layer 6. The casing 16 and the wiring layer 6 are bonded using, for example, an etching technique. For example, copper is used as the material of the housing 16.

  Next, the action that the stress applied to the semiconductor element 4 is relaxed when the semiconductor element 4 operates will be described. The semiconductor element 4 has an element part and a terminal part. The element portion is provided with a gate structure and is a portion through which a current flows. The termination portion is provided around the element portion and is a portion for improving the lateral breakdown voltage. For example, a pressure-resistant structure such as a guard ring and a RESURF layer is provided at the terminal portion.

  The heat generated when the semiconductor element 4 operates is greater in the element part than in the terminal part. In particular, a lot of heat is generated on the upper surface side of the element portion of the semiconductor element 4. For this reason, the temperature of the semiconductor element 4 has a distribution that increases on the upper surface side of the element portion. As shown in FIG. 3, when such a temperature distribution is formed, the upper surface side of the element portion thermally expands more than the remaining portion, so that it is curved and deformed so as to protrude upward.

  The elastic mechanism 10 can satisfactorily follow the curved deformation of the semiconductor element 4 by compressing and deforming the elastic body 14. Thereby, the stress applied to the semiconductor element 4 is relieved.

  Further, in the elastic mechanism 10, an electrical connection between the semiconductor element 4 and the wiring layer 6 and a heat conduction path are ensured through the contact body 12 and the housing 16, and low electrical resistance and high heat conduction characteristics are ensured. Is secured. Furthermore, since an electric current flows through the contact body 12 and the housing | casing 16, the influence of the inductance component of the elastic body 14 is suppressed.

  In the elastic mechanism 10, since one elastic body 14 is provided for one contact body 12, even if the size of the contact body 12 varies, the variation is absorbed by the elastic body 14. .

  Moreover, in the elastic mechanism 10, the edge part of the contact body 12 of the side which contacts the semiconductor element 4 is comprised by the curved surface, and the semiconductor element 4 and the contact body 12 are in point contact. Thereby, the stress applied to the semiconductor element 4 due to the sliding effect is relieved with respect to the thermal expansion of the semiconductor element 4 in the direction parallel to the contact surface between the semiconductor element 4 and the contact body 12.

  FIG. 4 shows another example of the elastic mechanism 10. In FIG. 4, only one of the plurality of elastic mechanisms 10 is shown for clarity of illustration. In this example, the contact body 22 includes a slide member 22a and a spherical member 22b. The slide member 22a has one end in contact with the elastic body 14 and the other end in contact with the spherical member 22b. The slide member 22 a is also in contact with the inner wall of the housing 16 and is slidable along the press-contact direction with respect to the housing 16. The spherical member 22b has one end in contact with the slide member 22a and the other end in contact with the semiconductor element 4 (not shown). The casing 26 has a concave groove formed in a part of the inner wall surface 26a, and the spherical member 22b is accommodated in the groove. The inner diameter 26W at the end of the casing 26 is configured to be smaller than the outer diameter 22W of the spherical member 22b. Thereby, the spherical member 22b is prevented from falling off from the casing 26. It should be noted that these structures for preventing disconnection are examples of the “prevention part” described in the claims. If such a drop prevention part is provided, the slide member 22a and the spherical member 22b are prevented from falling off during the operation of attaching the elastic mechanism 10 to the wiring layer 6, and the work load during manufacturing is reduced.

  Moreover, as shown in FIG. 5, the contact body 32 may have the slide member 32a and the collar part 32b. The slide member 32a may be the same as the contact body 12 shown in FIGS. The collar portion 32b is provided on a part of the side surface of the slide member 32a. The collar portion 32b may have a ring shape that makes a round of the side surface of the slide member 32a in the circumferential direction. Moreover, the collar part 32b may be comprised integrally with the slide member 32a. Also in this example, the contact body 32 is prevented from falling off from the housing 26.

  As shown in FIG. 6, the elastic mechanism 110 having the elastic body 114 and the contact body 112 may be accommodated in the groove 6 a provided in the wiring layer 6. The elastic body 114 and the contact body 112 may be the same as the elastic body 14 and the contact body 12 shown in FIGS. In this example, the casings 16 and 26 illustrated in FIGS. 2 to 5 are not necessary, and the configuration is simplified.

  As shown in FIGS. 7A and 7B, a drop prevention member 116 may be provided in the groove 6 a of the wiring layer 6. When the contact body 112 is accommodated in the groove 6 a of the wiring layer 6, the come-off prevention member 116 urges the contact body 112 along the lateral direction (left and right direction on the paper surface). This prevents the contact body 112 from falling out of the groove 6 a of the wiring layer 6.

  In this embodiment, the elastic mechanism portion 5 is provided only between the semiconductor element 4 and the wiring layer 6, but the same structure as the elastic mechanism portion 5 is also provided between the semiconductor element 4 and the insulating substrate 3. May be. In this case, when the semiconductor element 4 is bent and deformed, electrical connection and heat conduction paths are ensured on both the front surface and the back surface of the semiconductor element 4, so that the semiconductor element 4 can be operated stably. it can.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

1: Semiconductor module 2: Cooler 3: Insulating substrate 4: Semiconductor element 5: Elastic mechanism 6: Wiring layer 10, 110: Elastic mechanism 11: Cooler 12, 22, 32: Contact body 14, 114: Elastic body 16 , 26: housing

Claims (1)

A pressure contact type semiconductor module in which a semiconductor element and a wiring layer are pressure contact fixed,
A plurality of elastic mechanisms provided between the semiconductor element and the wiring layer and disposed in a plane orthogonal to the pressure contact direction ;
A plurality of drop prevention members ,
The elastic mechanism is
A conductive contact that contacts the semiconductor element;
An elastic body that urges the contact body toward the semiconductor element,
The wiring layer is provided with a plurality of grooves,
In each of the plurality of grooves of the wiring layer, the elastic mechanism and the prevention member are accommodated.
The disconnection preventing member is configured to bias the contact body along a direction orthogonal to the pressure contact direction when the contact body is accommodated in the groove of the wiring layer.
The semiconductor module is configured such that the semiconductor element and the wiring layer are electrically connectable via the contact body.

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