Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
  • H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
  • H01L23/495—Lead-frames or other flat leads
  • H01L23/49541—Geometry of the lead-frame
  • H01L23/49562—Geometry of the lead-frame for individual devices of subclass H10D
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L25/00—Assemblies consisting of a plurality of semiconductor or other solid state devices
  • H01L25/03—Assemblies consisting of a plurality of semiconductor or other solid state devices all the devices being of a type provided for in a single subclass of subclasses H10B, H10D, H10F, H10H, H10K or H10N, e.g. assemblies of rectifier diodes
  • H01L25/04—Assemblies consisting of a plurality of semiconductor or other solid state devices all the devices being of a type provided for in a single subclass of subclasses H10B, H10D, H10F, H10H, H10K or H10N, e.g. assemblies of rectifier diodes the devices not having separate containers
  • H01L25/07—Assemblies consisting of a plurality of semiconductor or other solid state devices all the devices being of a type provided for in a single subclass of subclasses H10B, H10D, H10F, H10H, H10K or H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group subclass H10D
  • H01L25/072—Assemblies consisting of a plurality of semiconductor or other solid state devices all the devices being of a type provided for in a single subclass of subclasses H10B, H10D, H10F, H10H, H10K or H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group subclass H10D the devices being arranged next to each other
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/01—Chemical elements
  • H01L2924/01078—Platinum [Pt]
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/095—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00 with a principal constituent of the material being a combination of two or more materials provided in the groups H01L2924/013 - H01L2924/0715
  • H01L2924/097—Glass-ceramics, e.g. devitrified glass
  • H01L2924/09701—Low temperature co-fired ceramic [LTCC]
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/19—Details of hybrid assemblies other than the semiconductor or other solid state devices to be connected
  • H01L2924/1901—Structure
  • H01L2924/1904—Component type
  • H01L2924/19041—Component type being a capacitor

Definitions

• This invention relates to improved semiconductor devices and, more particularly, to a package for high current semiconductor devices using one or more semiconductor chips.
• High power semiconductor devices are widely used but nonetheless costly. Their high cost stems principally from the use of expensive materials and complicated means of assembly. For example, prior art semiconductor power devices typically utilize massive copper bases, many internal piece parts, expensive ceramic insulators, and expensive assembly techniques.
• prior art power semi ⁇ conductor devices of high current carrying capacity are difficult or awkward to install, particularly when they must be grouped into arrays of several devices and isolated from the mounting surface.
• the shape and terminal arrangements of prior art devices make it inconvenient to assemble them to heat sinks and to the bus bars which interconnect the devices in an array.
• flexible leads are frequently provided requiring that bus bars be independently supported.
• many prior art devices do not meet the minimum terminal spacing requirements which have been established by the Underwriters Laboratories in Bulletin UL508, Table 18.1 dated August 19, 1977, as the recommended practice for components which are to be utilized in industrial environments. According to these recommendations, one-half inch (1.27 cm) is to be maintained through air between a high voltage (“hot”) lead and the heat sink or cabinet to which the device is mounted, and three-eighths inch
• one or more semiconductor chips are bonded to a planar portion of a first electrode or terminal member which has an opposed heat transfer face, and to which are also attached by insulating means at least one but usually a second and third electrode or terminal member.
• These terminal members are arranged in a spaced apart and substantially parallel relationship alongside the chip bonding region to permit simplified electrical connection of the semiconductor chips to the terminal members or electrodes.
• This assembly of parts is encapsulated, preferably in plastic, except that the heat transfer face and the terminal portions of the various electrodes are exposed.
• connection nuts are retained until electrical connection screws tighten whereupon they lift out of the complementary recesses so that final tightening torque is absorbed by the terminals.
• a dielectric adhesive material is used to insulate the second and third electrode members from the first electrode member. Electrical isolation of the device from a mounting surface is obtained by a separate or integral insulation layer.
• Figure 1 illustrates a prior art device of the threaded stud and pig-tail lead type
• FIG. 1 illustrates an improved prior art device
• FIG. 3 illustrates the internal members of the improved semiconductor device of the present invention
• Figure 4A-C illustrates different views of the encapsulated semiconductor device of the present invention wherein the terminals have been formed to retain the connection nuts, Fig. 4A showing upper surface features, Fig. 4B lower surface features, and Fig. 4C a side view;
• Figure 5 A-D illustrates different orientations in which the invented semiconductor device may be installed to achieve convenient bussing.
• Figure 1 illustrates a prior art example of a pig-tail lead type semiconductor power device 10 having a heavy hexagonal copper base 11, threaded mounting stud 12 and ceramic insulator 13.
• IJVTREAT connections to the device are through threaded stud 12 and braided pig-tail lead 14 by means of terminal connection 17.
• the control signals are applied through flexible leads 15-16 via terminals 18-19.
• power lead 14 is flexible, a bus bar used to interconnect devices of this type must be separately supported. This is a disadvantage. This type of prior art device is rugged, but is relatively expensive and awkward to isolate from a heat sink.
• Figure 2 illustrates improved power semiconductor device 20 having copper base 21, ceramic insulator 22 and semiconductor chip 23 in stacked relationship.
• Power is .fed into the device through terminals comprising tapped ferrules 24 and 28 which are fixed in the plastic encapsulating material and connected to the semiconductor die through leads 25 and 27, and flexible braided lead 26.
• Control signals are supplied through terminals 29 and 30 which are connected to semiconductor chip 23 by bonding wires 31 and 32.
• Plastic filled housing 34 surrounds the assembly. Holes 33 are used t mount device 20 to a heat sink.
• While device 20 overcomes a disadvantage of the prior art device of Figure 1 in that interconnecting bus bars may be supported by and attached directly to device terminals 24 and 28 without need for external support, many deficiencies remain. For example, a complex assembly of many internal piece parts is needed. There is a lack of rotational symmetry with respect to orientation of power terminals 2-4- and 28. It is difficult to access control signal terminals 29 and 30 in the presence of bus bars running across the top of the device. Additionally, the devices of Fig. 1 and 2 are designed for use with a single large semiconductor die, which leads to increased risk of die cracking during or after assembly.
• Internal device assembly 40 is constructed from first terminal member or electrode 41 having planar portion 42a-b, bent up portion 43, and terminal portion 44 which forms a high current or power terminal having connection hole 45 therein.
• Planar portion 42a-b has a first face 42a on which semiconductor chips 64-66 and terminal members 47 and 53 are mounted and a second opposite face 42b which serves as a heat transfer face for extracting heat from the finished device-.
• Second terminal member 47 having planar portion 48 is mounted on planar portion 42a of first member 41 by insulating means 60.
• Second terminal member or electrode 47 has bent up portion 49 and terminal portion 50 forming another power or high current terminal with connection hole 51.
• Signal or control lead terminal 58 with hole 59 is formed preferably of the same material as second terminal member 47, and is preferably a part thereof but of different thickness.
• Third terminal member 53 having planar portion 54 is attached to planar portion 42a of first terminal member 41 by insulating means 61.
• Third terminal member 53 has bent up portion 55 and terminal portion 56 with hole 57. Portion 56 with hole 57 forms another signal or control lead terminal.
• Second terminal member 47 and third terminal member 53 are in spaced apart relationship, defining therebetween bonding region 46 of planar portion 42a of first terminal member 41.
• One or more power semiconductor chips 64 are attached to first terminal member 41 in bonding region 46.
• '' Auxiliary semiconductor chips 65 and 66 may be optionally bonded to first terminal member 41 in bonding region 46, in other locations of planar portion 42a, or on planar por ⁇ tions 48 or 54 of terminal members 47 or 53.
• Semiconductor chips 64 are electrically coupled to planar portion 48 of second terminal member 47 by bonding wires 67, and to
• auxiliary chips 65 and 66 can be electrically coupled to second and/or third terminal members 47 and 53 and/or other chips as necessary to achieve a desired circuit function.
• Desirable auxiliary chips and intercon ⁇ nections are, for example, one or more power diodes (snubbers) connected across an emitter-collector of a power transistor chip to suppress transients, one or more speed-up diodes connected across an emitter-base of a power transistor or power Darlington chip to improve transient response, and/or one or more resistance means connected in series with emitters or bases of power transistors to improve current sharing among several transistor chips.
• Other auxiliary chips and connections are also useful.
• Terminal member 41 also serves as a sink for the heat generated • within the semiconductor chips, transferring this heat in turn to an external heat sink via heat transfer face 42b.
• the means used to bond, attach, or couple semiconductor chips 64-66 to terminal member 41 should desirably provide good thermal contact.
• An intermediate electrical isolation means can be used between any of the semiconductor chips and the terminal members if desired, provided good thermal contact is maintained.
• OMP could have been utilized.
• the same current handling capability can be obtained, for example, by using one large chip, or a multiplicity of smaller chips.
• Assembly 40 is particularly well suited for use with a multiplicity of chips. This is an advantage, since it is well known per se in the art that the yield of semiconductor chips decreases rapidly with increasing active chip area.
• a multiplicity of smaller chips operating in parallel can be used in place of a single large chip, and economic advantage realized thereby, provided that current flow through the individual chips is substantially equal.
• electrical parameters such as, for example, safe operating area, .switching time, and forward drop of individual chips be substantially matched. This may be accomplished by testing and selecting individual chips prior to assembly by means well known in the art.
• the same piece parts e.g. terminal members 41, 47 and 53 may be used to produce finished devices of a variety of current ratings simply by varying the number of parallel connected semiconductor die or chips bonded to assembly 40. This is a significant manufacturing convenience. The requirement for choosing die from the same wafer does not cause waste, since any die left over can be used for the assembly of individually packaged devices.
• members 47 and 53 to give approximately rectangular bonding region 46 permits chips 64-65 to be placed in region 46 in such a way as to permit wire bonding of the chips, for example, to members 47 and 53 without the wire bonds having to cross over each other. This simplifies assembly and reduces cost. Other techniques to connect to the devices may also be used.
• FIG. 4A-C illustrates a preferred embodiment of encapsulated semiconductor device 80 of the present invention, having plastic body 81 with mounting holes 82 and strength providing ridge 85.
• Heat transfer surface 42b protrudes a predetermined distance in the range 0-20 mils (0-0.050 cm) but preferably 2 mils (0.005 cm) from bottom surface 92 of body 81.
• Lower portions 98 of mounting holes 82 have been enlarged to accommodate drilling burrs which may be present on the external heat sink to which device 80 is attached, and which might otherwise prevent heat transfer surface 42b from making substantially uniform contact to the heat sink.
• Terminal portions 44, 50, 56 and 58 protrude from various locations of encapsulated device 80.
• Power terminal portions 50 and 44 have been bent inward to form inward facing and substantially coplanar terminal portions 83 and 84 with connection holes 51 and 45.
• Inward facing terminal portions 83 and 84 retain connection nuts 88 in portions 90 of plastic body 81 which have a shape comple ⁇ mentary to nuts 88 so as to prevent them initially from turning when connection screws (not shown) are installed through holes 45 and 51.
• Retained nuts 88 preferably have integral locking washer portions 89 facing upward toward the underside of inward facing terminal portion 83-84. The dimensions of nuts 88, complementary portions 90, and inward facing terminal portions 83-84 are adjusted so that distance 97 (Fig.
• Encapsulated device 80 is preferrably of approximately rectangular shape with terminal portions 83-84 diametri ⁇ cally opposed, arranged in this case approximately on a diagonal.
• Encapsulated device 80 is preferrably of approximately rectangular shape with terminal portions 83-84 diametri ⁇ cally opposed, arranged in this case approximately on a diagonal.
• encapsulated device 80 is 2.25 inches (5.7 cm) square with connection holes 45 and 51 located 1.76 inches (4.5 cm) apart symmetrically along a diagonal so that bus bars parallel to any opposed pair of substantially rectangular sides of device 81 can have
• encapsulated device 80 is 2.1 inches (5.3 cm) by 2.25 inches (5.7 cm) with connection holes 45 and 51 diagonally arranged and having lateral spacings (dimensions 142 and 143 of Fig. 5) of 1.25 inches (3.2 cm) and 1.29 inches (3.3 cm), which fix the corresponding bus bar spacing.
• Control signal terminals 56 and 58 protrude from a side of encapsulated device 80 and are separated from bottom plane 92 by distance 95 which preferably equals or exceeds current Underwriter Laboratories **1 minimum specifications of one-half inch (1.27 cm). Terminals 56 and 58 are separated by distance 94 which equals or exceeds Underwriters Laboratories' specifications of three-eighths inch (0.95 cm). Terminals 56 and 58 are substantially coplanar and separated from the plane of high current power terminals 83-84 by distance 93 which equals or exceeds Underwriters Laboratories' specifications of three-eighths inch (0.95 cm). Similarly, power terminal portions 83-84 are separated from base plane 92 by distance 91 of approximately 0.8 inch (2 cm).
• Control signal terminals 56 and 58 and power terminals 83-84 makes it possible to run bus lines in any direction across device 80 including those directions which cross over control signal terminals 56 and 58. This is a signi- ficant advantage and convenience to the user.
• Plastic body 81 is notched in portion 96 to permit terminals 56 and 58 to be bent into an upright position if desired.
• Control terminals 56 and 58 are preferably of dimensions to accept push-on connector plugs. However, other means of connection are satisfactory.
• Device 80 may be conveniently electrically isolated from an external heat sink on which it is to be mounted by providing an insulating washer between heat transfer surface 42b and the external heat sink.
• Mica and Kapton, both well known per se in the art are examples of suitable
• device 80 may include insulating layer 99 of good thermal conductivity permanently bonded to heat transfer face 42b.
• Low temperature glasses, insulating plastic, or adhesive ceramics are examples of materials suitable for insulating layer 99.
• additional metallic heat spreader lOO be bonded to insulating layer 99 so as to form metal-insulator-metal sandwich 101 comprising regions 42b-99-100.
• Metallic heat spreader 100 protects insulating layer 99 from abrasion or puncture and simplifies installation by the user.
• Sandwich 101 can be formed at the same time as terminal members 47 and 53 are attached to face 42a of terminal 41 and similar materials used. Copper, aluminum, steel and thermally conducting alloy materials are useful heat spreader materials.
• terminal members 41 and 47 are formed of 0.06 inch (0.15 cm) copper and terminal member 53 and control or signal terminal 56 are formed of 0.03 inch (0.08 cm) copper.
• Signal terminal 58 is conveniently formed from 0.06 inch (0.15 cm) copper as a part of terminal member 47 and thinned to 0.03 inch (0.08 cm).
• the copper is preferably nickel plated, but this is not essential. Other conductive materials such as aluminum or steel or combina ⁇ tions of metals may also be used.
• Insulating means 60 and 61 comprise a dielectric adhesive material of predetermined thickness, typically 10 mils (0.025 cm).
• Terminal members 41, 47 and 53 are stamped or etched typically from copper and formed to substantially the shape shown in Figure 3. These parts are preferably nickel plated although plating is not essential.
• Semiconductor chips 64 and, optionally, 65 and 66, are bonded to planar portion 42a of first terminal member 41 by methods well known per se in the art. Terminal member 41 is then placed in an alignment jig.
• Preforms of dielectric adhesive material 60 and 61 are applied to terminal members 47 and 53 which are then placed against terminal member 41 in the alignment jig and bonded together.
• An epoxy impregnated glass material may be conveniently used as the dielectric adhesive, but other materials such as ceramics, low temperature glasses or other materials with or without organic binders give satisfactory results.
• Wire bonds are formed by conventional means to electrically connect various regions of the semiconductor chips to the terminal members.
• a conventional die coat is applied and the completed assembly inserted in a mold cavity. Surface 42b of terminal member 41 is pressed tightly against a face of the mold cavity so that during encapsulation no plastic material penetrates beneath surface 42b.
• a slight depression is provided in the mold cavity conforming to the shape of surface 42b of terminal member 41 so that in the finished product, heat transfer surface 42b protrudes by a small amount, typically 2 mils (p.005 cm), from bottom surface 92 of plastic body 81.
• the assembly is encapsulated by methods well known per se in the art, preferably with a high strength plastic material such as a glass filled epoxy or a polyimide. Other materials such as low temperature glasses or ceramics may be used.
• a high strength plastic material such as a glass filled epoxy or a polyimide.
• Other materials such as low temperature glasses or ceramics may be used.
• the power terminals are conveniently formed so as to retain attachment nuts 88. It will be readily apparent to those skilled in the art that certain operations such as chip attachment, terminal member assembly, and forming can be carried out in a different sequence.
• terminal members 41, 47 and 53 may be formed to the shape illustrated in Fig. 3 before or after assembly.
• Figure 5A-D illustrates different orientations in which the invented semiconductor power device may be installed to achieve convenient bussing and control signal terminal arrangements.
• semiconductor device 120 with high current power terminals 121-122 and control signal terminals 123-124 is shown in top view connected to similar device 126 by bus bar 131 and further bus bars 130 and 132. Terminals 121-122 are separated by lateral spacing dimensions 142 and 143.
• Device 120 has been oriented with control signal terminals 123-124 facing to the right.
• Device 126 has control signal terminals facing up.
• the orientation of device 120 is held constant while similar devices 127-129 are rotated in ninety degree increments to illustrate the possible orientations.
• Bus bars 130-141 illustrate a number of possible means of interconnecting devices of varying orientation. For an embodiment where power terminals 121-122 are symmetrically located on the diagonal of the device, and dimensions 142 and 143 are equal, terminals 121-122 successively occupy the corners of a square as the device is rotated in ninety degree increments.
• a power terminals 121-122 are symmetrically located on the diagonal of the device, and dimensions 142 and 143 are equal, terminals 121-122 successively occupy the corners of a square as the device is rotated in ninety degree increments.
• Standard bus bar spacing may be adopted and either of the two high current power leads brought into contact with either of the two bus bars by simply rotating the device by ninety degrees in the arrangement of Figure 5B or 5C, or by one hundred and eighty degrees in the arrangement of Figure 5D. Where dimensions 142 and 143 are not equal, then rotation by one hundred and eighty degrees is required to interchange power terminals with fixed bus spacing.
• control signal terminals 123 and 124 have been located asymmetrically so that when devices 120 and 127 are placed facing each other that the control signal leads of device 120 interleave with those of device 127. This permits the devices to be more compactly arranged in an array and reduces the total space required.

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• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• Lead Frames For Integrated Circuits (AREA)
• Thyristors (AREA)

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• 1982
  • 1982-02-05 WO PCT/US1982/000153 patent/WO1982002980A1/en not_active Ceased
  • 1982-02-05 EP EP19820900877 patent/EP0076802A4/en not_active Ceased
  • 1982-02-05 JP JP57500924A patent/JPS58500187A/en active Pending
  • 1982-02-24 IT IT47859/82A patent/IT1156238B/en active
  • 1982-03-01 MX MX191622A patent/MX150708A/en unknown

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