JP2016127208A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device which can achieve sufficient charging of sealing resin even in the case of having a heat sink in which metal layers are provided on both surfaces of an insulating substrate.SOLUTION: A semiconductor device 1 comprises: a semiconductor element D; heat sinks 12, 22 for radiating heat from the semiconductor element D; and sealing resin 41 for sealing the semiconductor element D and the heat sinks 12, 22. The heat sinks 12, 22 have: insulating substrates 12b, 22b; first metal layers 12a, 22a laminated on the insulating substrates 12b, 22b on the semiconductor element D side; and second metal layers 12c, 22c laminated on the insulating substrates 12b, 22b on the side opposite to the semiconductor element D. Surfaces of the second metal layers 12c, 22c on the side opposite to the insulating substrates 12b, 22b are exposed externally from the sealing resin 41 and whole areas of outer peripheral edges of the second metal layers 12c, 22c lie outside outer peripheral edges of the insulating substrates 12b, 22b.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor device having a heat sink and sealed with resin.

  Some power semiconductor modules have a mounting structure that includes a semiconductor element and a heat radiating plate that guides heat generated in the semiconductor element to heat radiating fins and is entirely resin-sealed. For example, as described in Patent Documents 1 and 2, the heat radiating plate has a configuration in which metal layers are bonded to both surfaces of an insulating substrate made of a ceramic material having high thermal conductivity. One metal layer of the heat sink forms circuit wiring and is joined to a metal body that conducts heat from, for example, a semiconductor element in the sealing resin, and the other metal layer is attached to a heat radiating fin provided outside the sealing resin. Be joined.

JP 2008-04-1752 A JP 2014-060410 A

  In the mounting structure described above, the other metal layer of the two metal layers included in the heat sink is arranged so as to be exposed from the sealing resin on one surface side. However, in the resin sealing step, the resin may not be sufficiently filled in the vicinity of the outer peripheral edge of the other metal layer.

  This problem will be described with reference to FIG. In the semiconductor device 101 shown in FIG. 3A, a heat spreader 110 and a heat dissipation plate 120 are stacked on one surface of the semiconductor element D in this order from the semiconductor element D side. On the other surface of the semiconductor element D, a metal block 200, a heat spreader 210, and a heat sink 220 are laminated in order from the semiconductor element D side.

  The semiconductor element D and the heat spreader 110 are joined by a solder layer 310. The semiconductor element D and the metal block 200 are joined by a solder layer 320. The metal block 200 and the heat spreader 210 are joined by a solder layer 330.

  The heat sink 120 has a configuration in which a metal layer 120a, an insulating substrate 120b, and a metal layer 120c are stacked in this order from the semiconductor element D side. The heat sink 220 has a configuration in which a metal layer 220a, an insulating substrate 220b, and a metal layer 220c are stacked in this order from the semiconductor element D side.

  The entire laminate including the semiconductor element D and the upper and lower laminates of the semiconductor element D is sealed with a sealing resin 410. The surfaces of the metal layer 120c and the metal layer 220c opposite to the semiconductor element D side are exposed to the outside of the sealing resin 410.

  FIG. 3B shows a configuration near the outer peripheral edge of the heat sink 120. The outer peripheral edge Eb of the insulating substrate 120b is outside the distance h from the outer peripheral edge Ec of the metal layer 120c. Thereby, in the resin sealing step, among the regions to be sealed by the sealing resin 410, the region q close to the outside of the outer peripheral edge Ec is sandwiched between the insulating substrate 120b and the molding die G. Therefore, in order to fill the region q with the resin, the resin injected into the molding die G needs to wrap around the portion of the insulating substrate 120b over the distance h. Thereby, there exists a possibility that the injection | pouring resin may not fully be filled into the area | region q.

  If the resin is not sufficiently filled in the region q, a large stress is generated on the surface portion R of the insulating substrate 120b facing the region q during the cooling / heating cycle. As a result, the sealing resin 410 is likely to be peeled off and cracked.

  In view of the above problems, the present invention provides a semiconductor device capable of achieving sufficient filling of a sealing resin while including a heat sink having metal layers provided on both surfaces of an insulating substrate.

  The first invention is a semiconductor device comprising a semiconductor element, a heat radiating plate that radiates heat from the semiconductor element, and a sealing resin that seals the periphery of the semiconductor element and the heat radiating plate, The heat sink includes an insulating substrate, a first metal layer stacked on the surface of the insulating substrate on the semiconductor element side, and a second layer stacked on a surface of the insulating substrate opposite to the semiconductor element side. The surface of the second metal layer opposite to the insulating substrate side is exposed to the outside of the sealing resin, and the entire outer peripheral edge of the second metal layer is It is outside the outer peripheral edge of the insulating substrate.

  According to the first invention, the entire outer peripheral edge of the second metal layer is outside the outer peripheral edge of the insulating substrate. Therefore, a region that requires the injection resin to wrap around is not formed between the insulating substrate and the molding die. As a result, the semiconductor device has a configuration in which an unfilled portion of the sealing resin is unlikely to occur.

  ADVANTAGE OF THE INVENTION According to this invention, the semiconductor device which can achieve sufficient filling of sealing resin can be provided, providing the heat sink with which the metal layer was provided in both surfaces of the insulated substrate.

1A and 1B are views showing a semiconductor device according to an embodiment of the present invention, wherein FIG. 1A is a cross-sectional view showing the configuration of the semiconductor device, and FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the manufacturing method of the semiconductor device which concerns on embodiment of this invention, Comprising: (a)-(c) is a figure explaining each process. It is a figure which shows the semiconductor device which concerns on a prior art, Comprising: (a) is sectional drawing which shows the structure of a semiconductor device, (b) is sectional drawing which shows the filling defect of sealing resin.

  Hereinafter, embodiments will be described in detail with reference to FIGS. 1 and 2. In the semiconductor device according to the present embodiment, the entire outer peripheral edge of the metal layer having the surface exposed outside the sealing resin of the heat sink is outside the outer peripheral edge of the insulating substrate. Thereby, satisfactory filling of the sealing resin is achieved.

[Configuration of semiconductor device]
FIG. 1A shows the configuration of the semiconductor device 1 according to this embodiment.

  The semiconductor device 1 includes a semiconductor element D. The semiconductor element D is composed of, for example, a chip-shaped power semiconductor element, and is assumed here to be an IGBT (Insulated Gate Bipolar Transistor).

  On one surface of the semiconductor element D, a heat spreader 11 and a heat sink 12 are laminated in order from the semiconductor element D side. On the other surface of the semiconductor element D, a metal block 20, a heat spreader 21, and a heat sink 22 are laminated in order from the semiconductor element D side.

  The semiconductor element D and the heat spreader 11 are joined by a solder layer 31. The semiconductor element D and the metal block 20 are joined by a solder layer 32. The metal block 20 and the heat spreader 21 are joined by a solder layer 33.

  The metal block 20 is a spacer that secures a space for wire bonding to the semiconductor element D, and is made of, for example, copper. The heat spreader 11 and the heat spreader 21 are bulk bodies that diffuse heat from the semiconductor element D, and are made of, for example, copper.

  The heat sink 12 has a configuration in which a metal layer (first metal layer) 12a, an insulating substrate 12b, and a metal layer (second metal layer) 12c are stacked in this order from the semiconductor element D side. The heat sink 22 has a configuration in which a metal layer (first metal layer) 22a, an insulating substrate 22b, and a metal layer (second metal layer) 22c are stacked in this order from the semiconductor element D side. The insulating substrate 12b and the insulating substrate 22b are made of, for example, ceramics. The metal layer 12a, the metal layer 12c, the metal layer 22a, and the metal layer 22c are made of, for example, aluminum.

  The heat spreader 11 is joined to the metal layer 12a of the heat radiating plate 12. The heat spreader 21 is joined to the metal layer 22 a of the heat radiating plate 22.

  The heat spreader 11 and the heat dissipation plate 12 constitute a heat dissipation path on the collector side of the IGBT. The metal block 20, the heat spreader 21, and the heat dissipation plate 22 constitute a heat dissipation path on the emitter side of the IGBT.

  The entire laminate including the semiconductor element D and the upper and lower laminates of the semiconductor element D is sealed with a sealing resin 41. The surfaces of the metal layer 12c and the metal layer 22c opposite to the semiconductor element D side are exposed to the outside of the sealing resin 41.

  Next, with reference to FIG. 1 (b), the dimensions of the layers of the heat radiating plate 12 and the heat radiating plate 22 will be described with respect to the outward surface spread. Here, the relationship will be described using the heat radiating plate 12 as an example.

  FIG. 1B shows a portion near the outer peripheral edge of the heat radiating plate 12 shown in FIG. It is assumed that the insulating substrate 12b and the metal layer 12c have a rectangular shape having sides parallel to each other when the semiconductor device 1 is viewed from above the stack. In such a heat sink 12, the entire outer peripheral edge Ec of the metal layer 12c is outside the outer peripheral edge Eb of the insulating substrate 12b. In plan view, the length f (f> 0) at which the outer peripheral edge Ec protrudes from the position of the outer peripheral edge Eb may be arbitrary, and can take individual values in the spread of the metal layer 12c in each of the four directions. As a result, in the outer periphery of the heat radiating plate 12, a region requiring the wraparound of the injection resin as conventionally generated is not formed between the insulating substrate 12b and the molding die.

  Further, here, on either side of the rectangular metal layer 12c, the thickness of the insulating substrate 12b is set to t, and the dimension is set such that f ≦ t. Thereby, as will be described later, a large adhesion strength between the heat sink 12 and the sealing resin 41 is ensured.

  Moreover, in FIG.1 (b), the outer periphery Eb of the insulated substrate 12b exists on the outer side rather than the outer periphery Ea of the metal layer 12a. The positional relationship between the outer peripheral edge Eb and the outer peripheral edge Ea is not particularly limited, and may be at the same position in plan view, or the outer peripheral edge Ea may be outside the outer peripheral edge Eb. When the outer peripheral edge Eb is on the outer side of the outer peripheral edge Ea, the creeping distance on the insulating substrate 12b from the metal layer 12a to the metal layer 12c on the surface of the heat radiating plate 12 is increased. Increases performance.

  The same dimensional relationship as that of the heat sink 12 is applied to the heat sink 22. That is, the dimensional relationship between the metal layer 12a and the insulating substrate 12b is applied to the dimensional relationship between the metal layer 22a and the insulating substrate 22b, and the dimensional relationship between the insulating substrate 12b and the metal layer 12c is the same between the insulating substrate 22b and the metal layer 22c. Applies to dimensional relationships.

[Method for Manufacturing Semiconductor Device]
FIG. 2 shows a manufacturing process of the semiconductor device 1. First, as shown in FIG. 2A, the joined body of the heat radiating plate 12 and the heat spreader 11, the solder pellet 31A, the semiconductor element D, the solder pellet 32A, the metal block 20, and the solder pellet 33A are stacked in order. The reflow process is performed. Thereby, the solder pellet 31A, the solder pellet 32A, and the solder pellet 33A are once melted and then solidified.

  Next, as shown in FIG. 2B, a joined body of the heat spreader 21 and the heat radiating plate 22 is further stacked on the laminated body obtained in the first reflow process, and the second reflow process is performed. . Thereby, the solder pellet 31A, the solder pellet 32A, and the solder pellet 33A are again melted and solidified to become the solder layer 31, the solder layer 32, and the solder layer 33 in this order.

  Next, as shown in FIG. 2 (c), the laminate obtained in the second reflow step is placed in the molding die G (only the upper and lower portions of the molding die G are shown), and transfer mold is performed. Resin sealing is performed by injecting the resin T into the molding die G by a molding method such as the above. Thus, the semiconductor device 1 is completed.

[Effects of the embodiment, etc.]
According to the semiconductor device 1 of the present embodiment, the entire outer peripheral edge Ec of the second metal layer (metal layer 12c, metal layer 22c) is outside the outer peripheral edge Eb of the insulating substrate (insulating substrate 12b, insulating substrate 22b). It is in. Therefore, a region that requires the injection resin to wrap around is not formed between the insulating substrate and the molding die G. Thereby, the semiconductor device 1 has a configuration in which an unfilled portion of the sealing resin 41 hardly occurs. As described above, it is possible to provide a semiconductor device that can achieve sufficient filling of the sealing resin while including the heat dissipation plate provided with the metal layers on both surfaces of the insulating substrate.

  As described above, when an unfilled portion of the sealing resin 410 is formed in the region q of FIG. 3, a large stress is generated on the surface portion R of the insulating substrate facing the region q during the cooling / heating cycle. . However, according to the semiconductor device 1, it is difficult to form an unfilled portion of the sealing resin 41, and thus it is difficult to form a portion where such a large stress is generated. Moreover, according to the semiconductor device 1, as a result of good filling of the sealing resin 41, it is possible to suppress a stress value generated in the vicinity of the outer peripheral edge of the insulating substrate during the cooling / heating cycle. The stress value can be reduced to a level that is halved from the conventional value, such as about 10 MPa at an extremely low temperature of −40 ° C., for example.

  Further, as shown in FIG. 1B, the length f of the outer peripheral edge Ec protruding is set to be equal to or less than the thickness t of the insulating substrate, thereby sealing the heat sink (heat sink 12 and heat sink 22). A large adhesion strength with the resin 41 is ensured. For example, when f> t, the stress value generated between the heat sink and the sealing resin 41 at an extremely low temperature of −40 ° C. is 20 MPa or more, whereas when f ≦ t, The stress value falls within about 10 MPa to 15 MPa. Since the stress value is small, the sealing resin 41 is less likely to be peeled off from the heat sink.

  The present invention is applicable to a semiconductor device having a semiconductor element having a heat dissipation structure such as a power semiconductor element.

1, 101 Semiconductor device 20, 200 Metal block 11, 21, 110, 210 Heat spreader 12, 22, 120, 220 Heat sink 12a, 12c, 22a, 22c, 120a, 120c, 220a, 220c Metal layer 12b, 22b, 120b, 220b Insulating substrate 31, 32, 33, 310, 320, 330 Solder layer 31A, 32A, 33A Solder pellet 41, 410 Sealing resin D Semiconductor element Ea, Eb, Ec Outer peripheral edge f Length h Distance G Molding die q region R surface part t thickness

Claims (1)

A semiconductor element;
A heat sink for radiating heat from the semiconductor element;
A sealing resin for sealing the periphery of the semiconductor element and the heat sink;
The heat dissipation plate includes an insulating substrate, a first metal layer stacked on the surface of the insulating substrate on the semiconductor element side, and a first metal layer stacked on the surface of the insulating substrate opposite to the semiconductor element side. Two metal layers,
The surface of the second metal layer opposite to the insulating substrate side is exposed outside the sealing resin,
The semiconductor device according to claim 1, wherein the entire outer peripheral edge of the second metal layer is outside the outer peripheral edge of the insulating substrate.

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