JP4615289B2 - Semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device used for an inverter, a power conversion device of a motor driving device, and the like.

  FIG. 6 shows a power semiconductor device used in a conventional motor driving device. In the figure, a portion surrounded by a broken line is a semiconductor device body 1, which is soldered to a resin case 30 constituting the side surface of the semiconductor device body 1, a heat radiation metal base 20 constituting the bottom surface, and a heat radiation metal base 20. Insulating substrate 21, metal foils 22, 23, 24 bonded to insulating substrate 21, power semiconductor element 25 soldered on metal foil 23, semiconductor element 25 and metal foils 22, 23 are electrically connected Bonding wires 26 and 27, external lead-out terminals 10, and metal foils 22 and 24 and conductor bars 28 that electrically connect the external lead-out terminals 10. Further, a silicon gel 32 is sealed inside the semiconductor device body 1 to suppress vibrations of the bonding wires 26 and 27, and a thermoplastic engineering plastic lid 31 is bonded and sealed to the case 30 with a resin. ing.

In FIG. 6, the semiconductor device body 1 is fixed to the heat radiating fins 2 with screws 6 via grease 5. The grease 5 is applied between the semiconductor device body 1 and the radiation fin 2 so that heat generated in the semiconductor device body 1 is efficiently transmitted to the radiation fin. Furthermore, the conductor 4 electrically connected to the power circuit board 7 and the external lead-out terminal 10 of the semiconductor device body 1 are electrically connected by the screw 11 screwed into the case 30. Further, the conductor 3 and the external lead-out terminal 10 of the semiconductor device body 1 are electrically connected by the screw 11.
The conventional power semiconductor device is configured as described above.

  By the way, in the conventional device, when the semiconductor element 25 is short-circuited due to a short-circuit accident or the like, the semiconductor element 25 generates heat due to the short-circuit current, and accordingly, the silicon gel 32 is rapidly heated and expanded. In some cases, the internal pressure in the sealed semiconductor device suddenly increases, and the lid 31 may be damaged by the pressure. When the lid 31 is broken, the fragments or the silicon gel 32 may scatter around and damage the components on the power circuit board 7.

  Further, when the temperature of the semiconductor element 25 is further increased, the insulating substrate 21 is damaged due to a high temperature and the insulating property is lost, so that the metal foils 22, 23, 24 and the metal base 20 are electrically connected. May end up. Although the grease 5 applied between the metal base 20 and the radiating fin 2 has an insulating property, if the application is uneven, the metal base 20 and the radiating fin 2 may partially contact each other. In this case, since the radiating fin is grounded, a ground fault occurs, and a larger current flows through the semiconductor device body 1. As a result, the temperature of the silicon gel 32 further increased, and there was a risk that it would eventually ignite.

  As a countermeasure, a resin partition plate is provided between the power semiconductor element and the lid, and the partition plate is formed with a step portion formed on the inner side surface of the frame body, and a protrusion formed on the back side of the lid. Have been proposed in which a lid is prevented from being damaged by buffering a partition plate from an impact at the time of conduction breakdown of a power semiconductor element (see, for example, JP-A-2001-196487). See the official gazette).

In addition, a configuration has been proposed in which a case is provided with a safety valve for releasing the internal pressure of the semiconductor device to the outside (see, for example, Japanese Patent Laid-Open No. 05-175362).

JP 2001-196487 A (page 3 to page 5, FIGS. 2 to 10)

Japanese Patent Laid-Open No. 05-175362 (second page, FIG. 1)

However, the former (Japanese Patent Laid-Open No. 2001-196487) is a very small capacity semiconductor device, and even if the internal pressure of the case increases due to overcurrent, the lid is prevented from being broken and the silicon gel is scattered outside. However, in the case of a large-capacity semiconductor device, the above measures cannot prevent the lid from being damaged. Furthermore, it is impossible to prevent ignition due to a ground fault.

For this reason, in a large-capacity semiconductor device, when the internal pressure of the case becomes high due to overcurrent, a configuration in which the internal pressure of the case is released to the outside as in the latter case (Japanese Patent Laid-Open No. 05-175362) is preferable. When the safety valve is operated, the silicon gel scatters to the outside through the safety valve when the safety valve is operated. Since it is impossible to predict whether or not it will scatter in the direction, it is impossible to prevent damage to parts around the semiconductor device. Furthermore, it is impossible to prevent ignition due to a ground fault.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to prevent ignition due to damage to parts around a semiconductor device or a ground fault due to a short-circuit failure of a semiconductor element.

  In order to achieve the above object, a semiconductor device according to the present invention includes a case in which an upper part is opened and a semiconductor element is disposed at a bottom part, a resin filled in the case so as to cover the semiconductor element, A cover that covers the opening, and a structural member that restricts the opening direction and the opening width of the lid when the resin breaks due to an increase in internal pressure of the case and the lid opens. is there.

  In addition, in the semiconductor device according to the present invention, the structural member is configured to mechanically fix a part of the lid to the case, and to form a gap between the other part of the lid and the lid. Is provided.

  In the semiconductor device according to the present invention, the structural member may be configured such that a part of the lid is sandwiched between the case and a gap is formed between the structural member and the lid in the other part of the lid. It is provided in the case.

  In the semiconductor device according to the present invention, the structural member is fastened together with a screw that electrically connects a conductor and an internal wiring that electrically connect the semiconductor device to an external electric circuit and fixes the semiconductor device to the case. Are fixed to the case.

  In the semiconductor device according to the present invention, the structural member is constituted by a part of a conductor having a predetermined mechanical strength or a part of an internal wiring that connects the semiconductor device to an external electric circuit. Is.

  In the semiconductor device according to the present invention, the lid is made of glass epoxy resin.

  In the semiconductor device according to the present invention, the glass epoxy resin lid is fixed to the case with an epoxy resin.

  Further, in the semiconductor device according to the present invention, a part of the internal wiring that connects between the semiconductor element and the external lead-out terminal is provided with a fusing part that is quickly fused by an overcurrent, and the fusing part is provided with an overcurrent. In this case, the cover is blown before the lid is opened due to an increase in the internal pressure of the case.

  In the semiconductor device according to the present invention, the fusing portion is formed by forming a cutout portion in the internal wiring, and the cutout portion is provided as close as possible to the external lead-out terminal.

  In the semiconductor device according to the present invention, the internal wiring is constituted by a bonding wire connecting the semiconductor element and the external lead-out terminal, and the fusing portion is constituted by the bonding wire.

  In addition, the semiconductor device according to the present invention is screwed to the cooling fin via the insulating bush, and is electrically insulated from the cooling fin by inserting a high thermal conductive insulating sheet between the cooling fin. It is a thing.

  According to this invention, when the lid is opened due to an increase in the internal pressure of the case, the opening direction and the opening width of the lid are limited by the structural member. At the same time as limiting, the amount of scattering can be suppressed to a minimum, and damage to surrounding parts can be suppressed to a minimum.

  Further, according to the present invention, the structural member is fastened together with a screw that electrically connects a conductor and an internal wiring that electrically connect the semiconductor device to an external electric circuit and fixes the semiconductor device to the case. Since it is fixed to the case, it is not necessary to add a part for fixing the structural member to the case. Therefore, damage to peripheral parts can be minimized at a low cost.

  Further, according to the present invention, the structural member is constituted by a part of a conductor having a predetermined mechanical strength or a part of a semiconductor device component, which connects the semiconductor device to an external electric circuit. There is no need to prepare a separate structural member, and therefore, damage to peripheral components can be minimized at a low cost.

  Further, according to the present invention, since the lid is made of glass epoxy resin, the lid is not damaged before the lid is opened, and the scattering direction and the amount of scattering of the resin such as silicon gel are surely limited. can do.

  According to the present invention, since the glass epoxy resin lid is fixed to the case with an epoxy resin, the opening of the lid can be delayed until the melted portion in the semiconductor device is surely melted. Resin fire can be prevented.

  According to the present invention, a part of the internal wiring that connects between the semiconductor element and the external lead-out terminal is provided with a fusing part that is quickly fused by an overcurrent, and the fusing part is caused by the overcurrent. Since it is configured to melt before the lid opens due to an increase in the internal pressure of the case, it is possible to prevent ignition of a resin such as silicon gel.

According to the present invention, the fusing portion is formed by forming a cutout portion in the internal wiring, and the cutout portion is provided as close as possible to the external lead-out terminal. Can be reliably prevented.
That is, the bonding wire may be melted before the melted portion, and the melted end may be in contact with the internal wiring connecting the semiconductor element and the external lead-out terminal. Overcurrent continues to flow through the wiring. However, since the cutout portion constituting the cutout portion is provided as close as possible to the external lead-out terminal, the cutout end does not come into contact with the portion that hinders the action of the cutout portion, that is, the cutout portion and the metal Since it contacts the internal wiring part between the foil, if the overcurrent continues to flow to the internal wiring through the bonding wire after the fusing end is in contact with the internal wiring, the fusing part is surely blown, thus silicon gel or the like It is possible to reliably prevent the resin from firing. Incidentally, in the case where a cutout portion constituting a fusing portion is provided near the metal foil, the fusing end is in contact with the portion where the cutout portion is located between the internal wiring and the metal foil. Thus, the notch is not melted in the middle, and overcurrent continues to flow to the internal wiring through the bonding wire.

  Moreover, according to this invention, since the said fusion | melting part was comprised with the bonding wire, ignition of resin, such as a silicon gel, can be prevented.

  Furthermore, according to the present invention, since the insulation fin is electrically insulated from the cooling fin by screwing to the cooling fin via the insulating bush and inserting a high thermal conductive insulating sheet between the cooling fin, Even when the insulating substrate on which the semiconductor element is mounted is thermally damaged, it can be prevented from falling into a ground fault state, and ignition of a resin such as silicon gel can be suppressed.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIGS.
FIG. 1 is a longitudinal sectional view of a semiconductor device according to the first embodiment of the present invention, and FIG. 2 is a top view of the semiconductor device. In addition, in each figure, the same code | symbol is attached | subjected to the part same as what is shown in FIG.
1 and 2, 50 is a glass epoxy resin lid for closing the upper opening of the case 30, 51 is a comb-like resin structural member as shown in FIG. The lid 50 is sandwiched between the case 30 (one side portion of the lid 50), and a gap is formed between the lid 31 and the portion B in the figure (side portion facing the side sandwiched by the lid 50). As shown, the screws 30 are screwed into the case 30 and electrically fixed to the case 30 by screws 11 that electrically connect the conductors 3 and 4 and the external lead-out terminals 10. Reference numeral 52 denotes a cutout portion provided as close as possible to the external lead-out terminal 10 in the copper conductor bar 28 (in this embodiment, a horizontal portion located in the case 30 of the conductor bar 28). Before the lid 50 is opened, this portion is configured to be melted by energization with an overcurrent. Note that the notch 52 may be provided in a portion where the conductor bar 28 is embedded in the case 30. Further, the lid 50 and the case 30 are bonded with an epoxy resin. Reference numeral 60 denotes a high thermal conductive insulating sheet inserted between the semiconductor device main body 1 and the heat radiating fins 2, which transfers heat generated in the semiconductor device main body 1 to the heat radiating fins 2, and also the semiconductor device main body 1 and the heat radiating fins 2. Is electrically insulated. Reference numeral 61 denotes an insulating bush, and the semiconductor device body 1 is fixed to the cooling fin 2 with screws 6 via the insulating bush 61.
Other configurations are the same as those shown in FIG.

  In the above structure, an overcurrent flows through the semiconductor element 25, the bonding wires 26 and 27, the conductor bar 28, etc. due to a short circuit accident or the like, and the internal pressure of the semiconductor device body 1 suddenly rises and the case 30 is destroyed. When the lid 50 opens, as shown in FIG. 1, the lid 50 is sandwiched between the structural member 51 and the case 30 at the portion A as shown in FIG. Thus, the opening is made at the portion B, and the direction in which the silicon gel 32 is scattered can be limited to the direction B. At this time, since the opening width of the lid 50 is limited by the structural member 51, the amount of the silicon gel 32 scattered can be minimized.

  Further, conventionally, a thermoplastic engineering plastic has been generally used as the material of the lid 50. However, in the present embodiment, the glass having high pressure resistance, heat resistance, predetermined bending strength, and high thermal and mechanical strength. Epoxy resin is used. Since the conventional thermoplastic engineering plastic has low strength, the lid 50 may be broken before the adhesion between the lid 50 and the case 30 is peeled off, and the silicon gel 32 inside may be scattered. However, since the lid 50 made of strong glass epoxy resin is used in the present embodiment, the lid 50 is not broken before the lid 50 and the case 30 are peeled off, and the scattering direction of the silicon gel 32 is determined. It is possible to reliably limit the amount of scattering.

  Furthermore, in order for the silicon gel 32 to ignite, it is necessary to supply air from the outside at the same time that the silicon gel 32 is heated to a high temperature. In the present embodiment, the cutout portion 52 which is a melted portion of the conductor bar 28 is melted before the lid 50 is opened, and the short circuit current is cut off. For this reason, when the lid 50 is opened and air is supplied from the outside, the temperature rise due to the short-circuit current is stopped, and the ignition of the silicon gel 32 can be prevented.

Further, the bonding wires 26 and 27 may be melted before the cutout portion 52, and the melted end may contact a conductor bar (internal wiring) 28 that connects the semiconductor element 25 and the external lead-out terminal 10. In this case, overcurrent continues to flow to the internal wiring through the bonding wires 26 and 27. However, since the cutout portion 52 constituting the fusing portion is provided as close as possible to the external lead-out terminal 10, the fusing end does not come into contact with the portion that hinders the action of the cutout portion 52, that is, the cutout portion. Since the conductor bar 28 is in contact with the conductor bar 28 between the portion 52 and the metal foils 22, 24, an overcurrent continues to flow to the conductor bar 28 through the bonding wires 26, 27 after the fusing end contacts the conductor bar 28. The notch 52 can be surely melted, and thus the ignition of the resin 32 such as silicon gel can be reliably prevented.
Incidentally, when the cutout portion 52 constituting the fusing portion is provided near the metal foils 22 and 24, the cutout portion is between the metal foils 22 and 24 in the conductor bar 28. The contact portion will be contacted, and the cutout portion will not melt in the middle, and overcurrent will continue to flow to the conductor bar 28 through the bonding wires 26 and 27.

  Furthermore, in the present embodiment, the lid 50 and the case 30 are bonded with an epoxy resin that maintains the adhesive force even at high temperatures (for example, a high temperature of 800 ° C. or less at which silicon gel ignites). Since the epoxy resin has a strong adhesive force even at a high temperature, the opening timing of the lid 50 can be delayed, so that the cutout portion 52 of the conductor bar 28 is surely blown before the lid 50 is opened.

  In the conventional configuration, when the insulating substrate 21 is thermally damaged as described above, a ground fault occurs, and a rapid temperature increase due to the ground fault current promotes the ignition of the silicon gel 32. In the present embodiment, since the semiconductor device body 1 and the radiating fins 2 are insulated using the high thermal conductive insulating sheet 60 and the insulating bush 61, a ground fault may occur even when the insulating substrate 21 is thermally damaged. In addition, the ignition of the silicon gel 32 can be suppressed.

Embodiment 2. FIG.
4 is a longitudinal sectional view of a semiconductor device according to the second embodiment of the present invention, and FIG. 5 is a view of the semiconductor device as viewed from above. In addition, in each figure, the same code | symbol is attached | subjected to the part same as what is shown in FIGS. 1-3.
4 and 5, the conductor 4 having a predetermined mechanical strength that electrically connects the external lead-out terminal 10 of the semiconductor device body 1 and the power circuit board 7 extends rearward (on the lid 50 side), and The extended portion 4 </ b> A is bent toward the lid 50, and the lid 50 is sandwiched between the bent portion and the case 30. The conductor 3 connecting the external lead-out terminal 10 of the semiconductor device body 1 and an external electric circuit extends rearward (on the lid 50 side), and the extended portion 3A is bent toward the anti-lid 50 side. A gap is formed between the bent portion and the lid 50.
Other configurations are the same as those in the first embodiment.

  In the first embodiment shown in FIG. 1, the structure member 51 is configured to limit the opening direction and the opening width of the lid 50. However, in the second embodiment shown in FIGS. 4 and 5, the conductor 3 and the conductor 4 is configured to fulfill the function of the structural member 51. The operation of the present embodiment is the same as that of the first embodiment (overcurrent flows through the semiconductor element 25, the bonding wires 26 and 27, the conductor bar 28, etc. due to a short circuit accident or the like, and the internal pressure of the semiconductor device body 1 is increased. When the lid 50 suddenly rises and the lid 50 opens, the lid 50 is sandwiched between the extended portion 4A and the case 30 at the portion A, so the lid 50 opens at the portion B, and the silicon gel 32 Can be limited to the direction of B. At this time, since the opening width of the lid 50 is limited by the extension portion 3A, the amount of scattering of the silicon gel 32 can be minimized. However, the structural member 51 is not required and can be configured at low cost.

Embodiment 3 FIG.
In the first and second embodiments, the conductor bar 28 is provided with the notch 52 and this portion is melted. However, instead of providing the conductor bar 28 with the notch 52, The bonding wires 26 and 27 may be melted by reducing the number of wires or reducing the wire diameter.

In the second embodiment, a part of the conductors 3 and 4 is extended and this extended part is used as a substitute for the structural member 51. However, a part of the components of the semiconductor device may be used as a substitute for the structural member 51. .
For example, the structural member 51 may be substituted by bending / extending the external lead-out terminal 10 that is a part of the internal wiring to have the same function as the extended portions 3A and 4A of the conductors 3 and 4. .
In the first and second embodiments, one side of the lid 50 is directly fixed to the case 30 with the screw 11 without being sandwiched between the structural member 51 (or the conductor 4) and the case 30. In part, a lid receiving portion having a function similar to that of the structural member 51 or the extended portion 3A of the conductor 3 (having a predetermined gap with a side facing one side mechanically fixed, and when the lid is opened) The structural member 51 may be substituted by forming a lid receiving portion) that receives the lid so that the lid does not open more than a predetermined amount.

  The semiconductor device according to the present invention is suitable for use in a semiconductor device used for an inverter, a power conversion device of a motor drive device, or the like.

It is a longitudinal cross-sectional view of the semiconductor device which is Embodiment 1 of this invention. It is a top view of the semiconductor device which is Embodiment 1 of this invention. FIG. 3 is a diagram showing a state where a lid is opened in the first embodiment. It is a longitudinal cross-sectional view of the semiconductor device which is Embodiment 2 of this invention. It is a top view of the semiconductor device which is Embodiment 2 of this invention. It is a longitudinal cross-sectional view of the conventional semiconductor device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor device, 2 Radiation fin, 3, 4 conductors, 3A extension part, 4A extension part, 6 screws, 10 External lead-out terminal, 11 screws, 25 Power semiconductor, 26, 27 Bonding wire, 28 Conductor bar, 30 Case, 32 Silicon gel (resin), 50 Lid, 51 Structural member, 52 Notch, 60 High thermal conductive insulating sheet, 61 Insulating bush.

Claims (9)

The case where the upper part is open over the entire surface and the semiconductor element is arranged on the bottom part,
A resin filled to cover the semiconductor element within the case,
A lid arranged to close the opening of the case;
A structural member that supports the lid to be openable to the case only by a predetermined amount ;
The structural member is provided at a predetermined distance apart from a fixing portion that fixes the first side of the lid to the case and allows the second side facing the first side to be opened and closed, and the open side of the second side. A semiconductor device comprising: a locking portion that contacts and locks the second side when the lid is opened by a predetermined amount . Said structural member, said semiconductor device is a hand co tightening the external conductor and the internal wiring of an electrical circuit electrically connected to the screws that secure electrically connected to the case and is fixed to the casing The semiconductor device according to claim 1 . Said structural member is a semiconductor device according to claim 1, characterized in that it is constituted by a portion of the guide member to connect the semiconductor device to an external electric circuit. The lid, the semiconductor device according to claim 1, characterized in that it is made of glass epoxy resin 3. The semiconductor device according to claim 4 , wherein the lid is fixed to the case with an epoxy resin. A part of the internal wiring that connects between the semiconductor element and the external lead-out terminal is provided with a fusing part that is quickly fused by an overcurrent, and the fusing part is formed by increasing the internal pressure of the case due to the overcurrent. The semiconductor device according to claim 1 , wherein the semiconductor device is configured to be melted before the lid is opened. The semiconductor device according to claim 6 , wherein the fusing portion is formed by forming a cutout portion in the internal wiring, and the cutout portion is provided in the vicinity of the external lead-out terminal. The internal wiring, said a bonding wire connecting the semiconductor element and the external lead terminals, the semiconductor device according to claim 6, characterized in that constitutes the fusion portion by the bonding wire. Together is screwed to the cooling fins through an insulating bush, by inserting the high heat conductive insulating sheet between said cooling fins, claim 1, wherein the cooled fins and electrically insulated The semiconductor device according to any one of 8 .

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