JP4549287B2 - Semiconductor module - Google Patents

Description

  The present invention relates to a semiconductor module, and more particularly, to a semiconductor module using a semiconductor element that generates a large amount of heat.

  In a semiconductor module that generates a large amount of heat, for example, a power semiconductor element, a crack may occur in the solder member (joining member). This is likely to occur in a solder member that joins members having greatly different coefficients of thermal expansion. When the semiconductor module is repeatedly driven and stopped, the member joined by the solder member repeats thermal expansion and contraction corresponding to each thermal expansion coefficient, and the stress corresponding to the difference in thermal expansion and thermal contraction Is generated in the solder member to cause a crack. In particular, cracks are likely to occur at the periphery of a solder member having a large strain due to stress. When cracks occur, the thermal conductivity of the solder member decreases, and as a result, the heat dissipation efficiency of the semiconductor module decreases and the life is shortened.

  There exists a thing of patent document 1 as a semiconductor module which suppressed generation | occurrence | production of the crack in a solder member (including progress of the crack after generation | occurrence | production). FIG. 4 shows the semiconductor module of Patent Document 1. As shown in the drawing, the semiconductor module 510 includes an insulating substrate 516 having metal patterns 512 and 514 formed on both the main surface and the back surface, and a semiconductor element 518 bonded to the metal pattern 512 on the main surface with a solder member 524. A semiconductor mounting substrate 520, a metal base plate 522 to which the semiconductor mounting substrate 520 is bonded via the metal pattern 514 on the back surface of the insulating substrate 516, and a solder member 526 for bonding them.

  The heat generated from the semiconductor element 518 is transferred to the metal pattern 512 on the main surface via the solder member 524, and is then transferred to the insulating substrate 516, the metal pattern 514 on the back surface, the solder member 526, and the metal base plate 522 in order. Heat is radiated from the base plate 522 to the outside air.

  When the semiconductor module 510 is viewed from the stacking direction of the components of the semiconductor module 510 in order to suppress the occurrence of cracks in the peripheral portion 528 of the solder member 526, the peripheral edge of the metal pattern 514 on the back surface is outside the peripheral edge of the insulating substrate 516. It is comprised so that it may be located in. That is, the peripheral portion 530 of the metal pattern 514 on the back surface is not bonded to the insulating substrate 516, and therefore, the peripheral portion 530 is not disturbed by the insulating substrate 516 and is thermally expanded or contracted by the thermal expansion coefficient of the metal. (When bonded to the insulating substrate 516, the metal pattern 514 cannot expand or contract with the coefficient of thermal expansion of the metal, but expands or contracts with a coefficient of thermal expansion smaller than that of the metal and close to the insulating substrate 516. .) Therefore, the stress generated in the peripheral portion 530 of the solder member 526 sandwiched between the peripheral portion 530 of the metal pattern 514 on the back surface and the metal base plate 522 is the coefficient of thermal expansion of the metal pattern 514 and the metal base plate 522 on the back surface. The expansion or contraction is small, and the difference in expansion or contraction is small (small compared to the difference between the insulating substrate and the metal), and thus becomes small. As a result, the amount of strain due to stress is also reduced, and the generation and propagation of cracks at the peripheral edge 528 of the solder member 526 is suppressed.

JP 2000-101203 A

  However, due to the expansion of the scale of the semiconductor module, the circuit configuration, etc., when a plurality of the above-described semiconductor mounting substrates exist and the metal base plate is shared, that is, a plurality of semiconductor mounting substrates are provided on a single metal base plate. When soldering, not only is it necessary to provide each semiconductor mounting board with a metal pattern on the back surface, the periphery of which is located outside the insulating board, but in addition, the positioning accuracy in mounting is not good, It must be arranged and bonded to the metal base plate with a predetermined interval (margin) so as not to contact, and the installation area of the semiconductor mounting substrate becomes larger than the sum of the areas of the plurality of semiconductor mounting substrates. For this reason, a semiconductor module composed of a plurality of semiconductor mounting substrates and a single metal base plate is increased in size.

  On the other hand, when a plurality of semiconductor mounting substrates are combined into one insulating substrate, the size of the substrate increases, causing a problem such as newly appearing warpage, and stress generated at the peripheral portion of the solder member. Also increases the amount of strain due to heat, and air (bubbles) remains in the solder member under the board when joining to the metal base plate, causing deterioration of the thermal conductivity and reducing the reliability of the semiconductor module. There was a thing. Furthermore, when a plurality of semiconductor mounting boards are mounted on a metal base plate, the number of parts increases, resulting in a reduction in assembly efficiency.

  Therefore, the present invention does not increase in size even if it is necessary to join a plurality of semiconductor mounting board elements to a common metal base plate, and can suppress the occurrence and development of cracks in a solder member. An object of the present invention is to provide a semiconductor module.

In order to achieve the above object, a semiconductor module according to the present invention includes:
A semiconductor module in which a semiconductor mounting substrate comprising a plurality of insulating substrates provided with metal patterns on the main surface and the back surface and semiconductor elements bonded to the metal patterns on the main surface is bonded on a single metal base plate. There,
The plurality of insulating substrates in the semiconductor mounting substrate are arranged close to each other, and the metal pattern on the back surface is shared by a single thin metal plate,
The semiconductor mounting substrate and the metal base plate are joined using a solder member through the metal thin plate,
When viewed from the stacking direction of the insulating substrate and the thin metal plate, the peripheral edge of the thin metal plate is positioned outside the peripheral edge of the opposing insulating substrate.

  According to the present invention, in a semiconductor module composed of a plurality of semiconductor mounting substrate elements (insulating substrate units) and a single metal base plate, the metal pattern on the back surface of the plurality of insulating substrates is commonly configured by a single metal thin plate. Since the periphery is located outside the periphery of the insulating substrate, the generation of cracks in the solder member that joins the metal thin plate and the metal base plate is suppressed without increasing the size of the module.

Embodiment 1 FIG.
1 and 2 show a semiconductor module generally designated by reference numeral 10 according to an embodiment of the present invention. FIG. 2 is a view of a cross section of the semiconductor module 10 indicated by a one-dot chain line in FIG.

  The semiconductor module 10 has a semiconductor mounting block 16a composed of power semiconductor elements (semiconductor chips) 12a to 12d such as IGBT (Insulated Gate Bipolar Transistor) and a substrate 14a on which these chips are mounted, which generate a large amount of heat during driving. In this structure, the semiconductor mounting substrate 16 composed of the semiconductor chips 12e to 12h and the semiconductor mounting block 16b including the substrate 14b on which these chips are mounted is mounted on one metal base plate 18. Although not shown, the semiconductor module 10 is configured such that the heat dissipation fins are in contact with the metal base plate 18 or the whole is covered with a resin package as required.

  The substrates 14a and 14b in the semiconductor mounting blocks 16a and 16b are circuit patterns (hereinafter referred to as “main surfaces”) made of thin metal plates on the main surfaces (surfaces bonded to the semiconductor chips) of the insulating substrates 20a and 20b made of ceramic. This is called a “pattern”.) 22a and 22b are formed. A circuit pattern (hereinafter referred to as a “back pattern”) made of a thin metal plate is used for the back surfaces (surfaces to be joined to the metal base plate 18) of the insulating substrates 20a and 20b of the substrates 14a and 14b. 24a and 24b are also formed. The back surface patterns 24a and 24b are integrated as a structure in the semiconductor mounting substrate 16, that is, are formed of a single metal thin plate 24, and a part of the metal thin plate 24 corresponding to each of the substrates 14a and 14b is provided for convenience. It is shown in The main surface patterns 22a and 22b and the metal thin plate 24 are made of, for example, aluminum or copper. The material of the main surface patterns 22a and 22b and the material of the metal thin plate 24 may be different or the same.

  In the substrates 14a and 14b, the main surface patterns 22a and 22b and the metal thin plates 24 (back surface patterns 24a and 24b) are joined to the insulating substrates 20a and 20b through a brazing material (not shown) using, for example, an active metal method. Has been done.

  In this case, the distance between the insulating substrates 20a and 20b bonded to the metal thin plate 24 is narrower because it is positioned with higher accuracy than the case where individual semiconductor mounting substrates whose back surface patterns are not integrated are bonded to the metal base plate. can do. Further, since the semiconductor mounting substrate 16 is not the periphery of the solder member between the insulating substrates 20a and 20b, it is basically unnecessary to take measures against cracking of the solder member, and in the process of forming the joint between the metal thin plate and the insulating substrate. It can be said that it is sufficient to take a slight distance in consideration of the positioning accuracy and the influence of thermal expansion. Thereby, even if it provides a several semiconductor mounting board | substrate element in a single metal base board, the enlargement of a semiconductor module can be suppressed.

  For example, the distance D between the insulating substrates 20a and 20b in the present embodiment can be the same as or smaller than the width W of the peripheral edge 38 of the metal thin plate 24 (D ≦ W). Therefore, conventionally, since each semiconductor mounting substrate has to be provided with a peripheral portion, the required distance between the insulating substrates in the two semiconductor mounting substrates is at least 2 × W. In this embodiment, The distance can be reduced to at least 1/2 or less.

  The metal base plate 18 is for releasing heat generated by driving the semiconductor mounting blocks 16a and 16b in the semiconductor mounting substrate 16 to the outside. The metal base plate 18 is preferably made of the same material as that of the metal thin plate 24 or a material having substantially the same thermal expansion coefficient, and is made of, for example, aluminum or copper. Further, the metal base plate 18 generally has a through hole 26 for attaching the semiconductor module 10 to another device using a screw.

  As shown in FIG. 2, the substrates 14 a and 14 b and the semiconductor chips 12 a to 12 h are joined by joining the semiconductor chips 12 a to 12 h to the main surface patterns 22 a and 22 b via a solder member 28. Further, the bonding between the substrates 14 a and 14 b and the metal base plate 18, in other words, the bonding between the semiconductor mounting substrate 16 and the metal base plate 18 is performed by bonding the metal base plate 18 to the metal thin plate 24 via the solder member 30. Done.

  Further, as shown in FIG. 2, the semiconductor module 10 is viewed from the stacking direction of the components of the semiconductor module 10 in order to suppress the occurrence and development of cracks in the peripheral portion 32 of the solder member 30, that is, FIG. 1. As shown in FIG. 3, the entire periphery (contour) 34 of the thin metal plate 24 is configured to be located outside the periphery (contours) 36a and 36b of the insulating substrates 20a and 20b. In other words, the peripheral portion 38 (cross hatched portion in FIG. 1) of the metal thin plate 24 is not joined to the insulating substrates 20a and 20b. Therefore, the peripheral portion 38 of the metal thin plate 24 can be thermally expanded or contracted by the thermal expansion coefficient of the metal without being obstructed by the insulating substrates 20a and 20b (when bonded to the insulating substrates 20a and 20b). The metal cannot be expanded or contracted at the thermal expansion coefficient of the metal, and is thermally expanded or contracted at a thermal expansion coefficient smaller than that of the metal and close to the insulating substrates 20a and 20b). Therefore, the stress generated in the peripheral portion 32 of the solder member 30 that joins the peripheral portion 38 of the metal thin plate 24 and the metal base plate 18 is the coefficient of thermal expansion of the metal that is substantially the same in the metal thin plate 24 and the metal base plate 18. And the difference in expansion amount or contraction amount is small (smaller than the difference in expansion amount or contraction amount between the insulating substrate and the metal). As a result, the amount of strain due to stress is also reduced, and the generation and propagation of cracks at the peripheral edge 32 of the solder member 30 is suppressed.

  When joining the semiconductor mounting blocks 16a and 16b and the metal base plate 18, that is, when joining the metal thin plate 24 and the metal base plate 18 in the semiconductor mounting substrate 16 via the solder member 30, the metal thin plate 24 and the metal base The metal thin plate 24 is preferably provided with a through hole 40 for extracting air so that no air remains between the plate 18 and the plate 18. When air remains (in other words, when air bubbles exist in the solder member 30), the thermal conductivity of the solder member 30 decreases. Thereby, heat is not sufficiently transmitted to the metal base plate 18 via the solder member 30, and as a result, the life of the semiconductor module 10 may be reduced. As shown in FIG. 1, the through hole 40 in the present embodiment is provided at the center of the thin metal plate 24, that is, between the two semiconductor mounting blocks 16a and 16b. Note that the through hole is not limited to the slit shape as shown in FIG.

  When the semiconductor module 10 is driven (when the semiconductor chips 12a to 12h are driven), most of the heat generated from the semiconductor chips 12a to 12h is transmitted to the main surface patterns 22a and 22b of the insulating substrates 20a and 20b via the solder member 28. . Next, heat is transmitted from the main surface patterns 22 a and 22 b to the metal thin plate 24 through the insulating substrates 20 a and 20 b, and further to the metal base plate 18 through the solder member 30. Then, heat is radiated from the metal base plate 18 to the outside. At this time, the metal base plate 18 and the metal thin plate 24 are thermally expanded (other members are also thermally expanded).

  According to the semiconductor module of the present embodiment, the metal thin plate and the metal base plate are arranged so that the peripheral edge of the metal thin plate joined to the metal base plate is arranged outside the peripheral edge of each opposing insulating substrate. The generation and propagation of cracks at the peripheral edge of the solder member that joins are suppressed. In addition, a semiconductor module in which a plurality of semiconductor mounting substrate elements (insulating substrate units) are bonded to a single metal base plate has a plurality of semiconductor mounting substrate elements as semiconductor mounting blocks and the back surface pattern of the insulating substrate is a single metal. Since it is formed of a thin plate and configured as a single semiconductor mounting substrate, the installation area as the semiconductor mounting substrate is reduced (compared to the case where the back surface pattern is not formed of a single metal thin plate), and as a result, the semiconductor An increase in the size of the module is suppressed (the so-called high integration in which the occupation ratio of the semiconductor mounting substrate to the entire semiconductor module increases). Furthermore, since a plurality of semiconductor mounting blocks corresponding to each insulating substrate can be handled as one semiconductor mounting substrate, the number of parts at the time of assembly can be reduced, and the assembly efficiency can be improved.

Embodiment 2. FIG.
The present embodiment is different from the above-described embodiment in that the insulating substrate in the semiconductor mounting substrate and a partial relationship between the insulating substrate and the metal thin plate are different.

  For specific description, FIG. 3 shows a configuration of a semiconductor module generally designated by reference numeral 110 according to the present embodiment. Similar to the semiconductor module 10 of the above-described embodiment, the semiconductor module 110 has a structure in which a semiconductor mounting substrate 116 including two semiconductor mounting blocks 116 a and 116 b is bonded to a metal base plate 118.

  Each of the semiconductor mounting blocks 116a and 116b of the semiconductor mounting substrate 116 includes a plurality of semiconductor chips 112a to 112h and substrates 114a and 114b on which these chips are mounted, respectively, similarly to the two semiconductor mounting blocks 16a and 16b of the above-described embodiment. Composed. The substrates 114a and 114b are composed of insulating substrates 120a and 120b, main surface patterns 122a and 122b, and back surface patterns 124a and 124b, similarly to the substrates 14a and 14b of the above-described embodiment. Note that these back surface patterns 124 a and 124 b are integrally formed as a structure in the semiconductor mounting substrate 116, that is, formed of a single metal thin plate 124. Further, as in the above-described embodiment, the bonding between the semiconductor chips 112a to 112h and the main surface patterns 122a and 122b of the substrates 114a and 114b and the bonding between the metal thin film 124 and the metal base plate 118 are performed by solder members (not shown). Is done through.

  When viewed from the stacking direction of the insulating substrates 120a and 120b and the thin metal plate 124, the semiconductor module 110 of the present embodiment has the entire periphery 134 of the thin metal plate 124 as the insulating substrate 120a, as in the semiconductor module 10 of the above-described embodiment. It is not configured to be arranged outside the peripheral edges 136a and 136b of 120b. In other words, a part of the peripheral edge 134 of the thin metal plate 124 is configured to exist inside or at the same position as the peripheral edges 136a and 136b of the insulating substrates 120a and 120b.

  The reason for this will be described. The metal base plate 118 and the metal thin plate 124 are thermally expanded by releasing heat from the semiconductor chips 112a to 112h, or are thermally contracted by stopping the release of heat. In particular, portions (regions) of the metal base plate 118 and the metal thin plate 124 that are relatively close to the semiconductor chips 112a to 112h expand or contract significantly compared to other portions. In other words, the amount of expansion or contraction of the metal base plate 118 or the metal thin plate 124 that is relatively far from the semiconductor chips 112a to 112h is relatively small. Therefore, the portion of the solder member that joins the metal base plate 118 and the metal thin plate 124 far from the semiconductor chip is less likely to crack compared to other portions. Therefore, as shown in FIG. 3 (when viewed from the stacking direction of the insulating substrates 120a and 120b and the thin metal plate 124), the entire peripheral edge 134 of the thin metal plate 124 is the peripheral edge 136a of the insulating substrates 120a and 120b as in the above-described embodiment. The peripheral edge 134 of the metal thin plate 124 is less than the peripheral edges 136a and 136b of the insulating substrates 120a and 120b at the peripheral edges 136a and 136b of the insulating substrates 120a and 120b in the vicinity of the semiconductor chips 112a to 112h. What is necessary is just to be located outside.

  Considering this, the layout on the insulating substrates 120a and 120b is determined. For example, as in the semiconductor module 110 shown in FIG. 3, the semiconductor chips 112a to 112h, which are heating elements, are disposed on one side (the upper side in the figure) on the insulating substrates 120a, 120b, and the wire wiring 150a, which is not a heating element, for example. The layout is designed so that the wiring lead-out regions 152a and 152b from which the lead 150b is drawn out are arranged on the other side (lower side in the figure). In the semiconductor module 110 having the layout on the insulating substrates 120a and 120b, the metal thin plate 124 is a metal thin plate in the vicinity of the semiconductor chips 112a to 112h when viewed from the stacking direction of the insulating substrates 120a and 120b and the metal thin plate 124. 124 is located outside the peripheral edges 136a and 136b of the insulating substrates 120a and 120b, and the peripheral edge 134 of the thin metal plate 124 is located near the insulating substrates 120a and 120b in the vicinity of the wiring lead-out regions 152a and 152b far from the semiconductor chips 112a to 112h. It is comprised so that it may be located inside or the same as the periphery 136a, 136b.

  According to this embodiment, the thin metal plate is not configured so that the entire periphery of the thin metal plate is located outside the peripheral edge of the insulating substrate, that is, the peripheral edge of the thin metal plate is partly inside the peripheral edge of the insulating substrate. Or since it is made to be the same position, compared with the above-mentioned embodiment, the quantity of the material which forms a metal thin plate can be decreased, and the area as a semiconductor mounting substrate can also be made small.

  Moreover, you may provide the through-hole for extracting air at the time of solder joining of a metal thin plate and a metal base plate like the above-mentioned embodiment.

  Finally, the semiconductor modules of the two embodiments described above are formed from two semiconductor mounting blocks, but are not limited thereto. According to the present invention, as the number of semiconductor mounting blocks constituting the semiconductor module increases, the effect of suppressing the increase in the size of the semiconductor module increases.

It is a figure which shows the semiconductor module which concerns on Embodiment 1 of this invention. It is sectional drawing of the semiconductor module seen from the A direction shown in FIG. It is a figure which shows the semiconductor module which concerns on Embodiment 2 of this invention. It is sectional drawing of the conventional semiconductor module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Semiconductor module, 16a, 16b Semiconductor mounting block, 16 Semiconductor mounting board, 18 Metal base board, 20a, 20b Insulating board, 24 Metal thin plate, 24a, 24b Back metal pattern, 34 Perimeter (contour) of metal thin plate, 36a, 36b Insulation substrate periphery

Claims (3)

A semiconductor module in which a semiconductor mounting substrate comprising a plurality of insulating substrates provided with metal patterns on the main surface and the back surface and semiconductor elements bonded to the metal patterns on the main surface is bonded on a single metal base plate. There,
The plurality of insulating substrates in the semiconductor mounting substrate are arranged close to each other, and the metal pattern on the back surface is shared by a single thin metal plate,
The semiconductor mounting substrate and the metal base plate are joined using a solder member through the metal thin plate,
A semiconductor module, wherein when viewed from the stacking direction of the insulating substrate and the thin metal plate, the peripheral edge of the thin metal plate is positioned outside the peripheral edge of the opposing insulating substrate. A semiconductor module in which a semiconductor mounting substrate composed of a plurality of insulating substrates each having a metal pattern formed on the main surface and the back surface and a semiconductor element bonded to the metal pattern on the main surface is bonded on a single metal base plate. There,
The plurality of insulating substrates in the semiconductor mounting substrate are arranged close to each other, and the metal pattern on the back surface is shared by a single thin metal plate,
The semiconductor mounting substrate and the metal base plate are joined using a solder member through the metal thin plate,
When viewed from the stacking direction of the insulating substrate and the metal thin plate, the periphery of the metal thin plate is located outside the peripheral portion of the insulating substrate in the peripheral portion of the insulating substrate in the vicinity of the semiconductor element. module. The semiconductor module according to claim 1, wherein a through hole is formed in a portion of the thin metal plate that is between the plurality of insulating substrates and is not joined to the insulating substrate.

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