US20140097527A1 - Method of manufacture integrated circuit package - Google Patents
Method of manufacture integrated circuit package Download PDFInfo
- Publication number
- US20140097527A1 US20140097527A1 US13/644,647 US201213644647A US2014097527A1 US 20140097527 A1 US20140097527 A1 US 20140097527A1 US 201213644647 A US201213644647 A US 201213644647A US 2014097527 A1 US2014097527 A1 US 2014097527A1
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- United States
- Prior art keywords
- leadframe
- shunt
- integrated circuit
- tape
- circuit device
- Prior art date
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- Granted
Links
- 238000000034 method Methods 0.000 title claims description 27
- 238000004519 manufacturing process Methods 0.000 title claims description 13
- 239000012778 molding material Substances 0.000 claims description 16
- 229910045601 alloy Inorganic materials 0.000 claims description 11
- 239000000956 alloy Substances 0.000 claims description 11
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 6
- 229910052802 copper Inorganic materials 0.000 claims description 6
- 239000010949 copper Substances 0.000 claims description 6
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
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- 239000004416 thermosoftening plastic Substances 0.000 claims description 3
- 238000005538 encapsulation Methods 0.000 abstract description 6
- 229910000881 Cu alloy Inorganic materials 0.000 description 6
- 229910000896 Manganin Inorganic materials 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
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- 238000010586 diagram Methods 0.000 description 3
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- 230000008901 benefit Effects 0.000 description 2
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- 238000012986 modification Methods 0.000 description 2
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- 230000008859 change Effects 0.000 description 1
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Images
Classifications
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- 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
- H01L23/49517—Additional leads
- H01L23/4952—Additional leads the additional leads being a bump or a wire
-
- 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
- H01L23/49517—Additional leads
- H01L23/49531—Additional leads the additional leads being a wiring board
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
- H01L21/56—Encapsulations, e.g. encapsulation layers, coatings
- H01L21/568—Temporary substrate used as encapsulation process aid
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/02—Bonding areas; Manufacturing methods related thereto
- H01L2224/04—Structure, shape, material or disposition of the bonding areas prior to the connecting process
- H01L2224/05—Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
- H01L2224/0554—External layer
- H01L2224/0555—Shape
- H01L2224/05552—Shape in top view
- H01L2224/05554—Shape in top view being square
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/42—Wire connectors; Manufacturing methods related thereto
- H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
- H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
- H01L2224/4805—Shape
- H01L2224/4809—Loop shape
- H01L2224/48091—Arched
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/42—Wire connectors; Manufacturing methods related thereto
- H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
- H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
- H01L2224/481—Disposition
- H01L2224/48135—Connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip
- H01L2224/48137—Connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip the bodies being arranged next to each other, e.g. on a common substrate
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/42—Wire connectors; Manufacturing methods related thereto
- H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
- H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
- H01L2224/481—Disposition
- H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
- H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
- H01L2224/48245—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
- H01L2224/48247—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a bond pad of the item
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/42—Wire connectors; Manufacturing methods related thereto
- H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
- H01L2224/49—Structure, shape, material or disposition of the wire connectors after the connecting process of a plurality of wire connectors
- H01L2224/491—Disposition
- H01L2224/4912—Layout
- H01L2224/49171—Fan-out arrangements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/28—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection
- H01L23/31—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection characterised by the arrangement or shape
- H01L23/3107—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection characterised by the arrangement or shape the device being completely enclosed
- H01L23/3121—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection characterised by the arrangement or shape the device being completely enclosed a substrate forming part of the encapsulation
Definitions
- An integrated circuit package serves to physically and electrically connect an integrated circuit device (housed within the integrated circuit package) to a printed circuit board.
- One type of integrated circuit package is known as a “flat no-leads package”. This type of package is a surface-mount technology that connects an integrated circuit device to surfaces of the printed circuit board without the use of through-holes. Perimeter lands on the package bottom provide electrical connections to the printed circuit board.
- Flat no-leads packages typically include a planar copper leadframe substrate upon which the integrated circuit device is mounted. The leadframe and the integrated circuit device are typically encapsulated within a molding material.
- Flat no-lead packages generally include an exposed thermal pad to improve heat transfer out of the integrated circuit device (and into the printed circuit board).
- QFN quad-flat no-leads
- DFN dual-flat no-leads
- a rectangular copper alloy slug or shunt be included in the package with one surface exposed for soldering.
- FIG. 1 is a plan view of exemplary block of connected leadframe sheets.
- FIG. 2 is a plan view of one of the leadframe sheets of FIG. 1 .
- FIG. 3 is a plan view of an exemplary leadframe from the leadframe sheet of FIG. 2 .
- FIG. 4 is a cross-section view of the leadframe of FIG. 3 , taken along the line 4 - 4 in FIG. 3 .
- FIG. 5 is a cross-section view similar to that of FIG. 4 , but showing the leadframe of FIG. 3 having tape applied to its lower surface.
- FIG. 6 is a plan view of the leadframe of FIG. 3 , illustrating a shunt supported on the tape shown in FIG. 5 , an integrated circuit device mounted on a die pad of the leadframe and wirebonding between the integrated circuit device, the shunt and the leadframe.
- FIG. 7 is a cross-section view of the leadframe of FIG. 6 , taken along the line 7 - 7 in FIG. 6 .
- FIG. 8 is a perspective view of a completed integrated circuit package.
- FIG. 9 illustrates by flow diagram, selected steps in an exemplary method for manufacturing an integrated circuit package according to the present disclosure.
- FIG. 10 illustrates by flow diagram, one embodiment of a method of manufacturing an integrated circuit package.
- FIG. 11 illustrates by flow diagram, another embodiment of a method of manufacturing an integrated circuit package.
- a rectangular copper alloy slug or shunt be included in the package with one surface exposed for soldering.
- the copper alloy used in the shunt may, for example, be of the type sold under the trademark MANGANIN®, and may, for example, have a composition of about 86% copper, 12% manganese, and 2% nickel. Because of the relatively high cost of this alloy, it is advantageous to have the leadframe formed from a less expensive leadframe alloy, for example, the alloy sold under the trade designation “CDA194”. CDA194 is well suited and characterized both thermally and mechanically for use in leadframes. It is also formulated to facilitate stamping and etching of leadframes.
- an integrated circuit package along with a method of manufacturing the package, are disclosed herein.
- the disclosed package and method of manufacture provide the ability, for example, to incorporate a slug or shunt made of a more expensive copper alloy (e.g., MANGANIN®) into a package having its leadframe manufactured from a less expensive leadframe alloy.
- MANGANIN® a more expensive copper alloy
- the alloy CDA194 is widely used for leadframes and is readily available from rolling mills. MANGANIN®, however, is generally less widely used and available.
- FIG. 1 illustrates a block 10 of connected leadframe sheets 22 , 24 , 26 , and 28 .
- FIG. 2 illustrates the leadframe sheet 22 in further detail, it being understood that the remaining leadframe sheets 24 , 26 , and 28 may be substantially identical to the leadframe sheet 22 .
- the leadframe sheet 22 may include a plurality (e.g., eighty-eight, as depicted in FIG. 2 ) of leadframes 30 including the individual leadframes 32 , 34 , 36 , 38 and 40 .
- FIG. 3 illustrates the leadframe 40 in further detail, it being understood that the remainder of the leadframes 30 may be substantially identical to the leadframe 40 . It is noted that, for purposes of illustrative efficiency, the package and method of manufacture will be described herein specifically in conjunction with the exemplary leadframe 40 . It is to be understood, however, that the methodology described may be carried out on all of the leadframes 30 while they are still connected to one another in the leadframe sheet 22 and while the leadframe sheets 22 , 24 , 26 , and 28 are still connected to one another in the leadframe block 10 .
- the leadframe 40 may include a frame portion 42 having an upper surface 44 and an oppositely disposed lower surface 46 ( FIG. 4 ).
- a plurality of tabs 50 may extend inwardly from the frame 42 , as shown.
- the tops of the tabs 50 are the targets for wire bonding connections to the integrated circuit device (in a manner that will be described in further detail herein).
- the right side (as viewed in the orientation of FIG. 3 ) of the leadframe 40 may be occupied by a die mounting pad 70 for mounting an integrated circuit device, in a manner as will be described in further detail herein.
- the left side of the leadframe 40 may include an open space 80 that extends completely through the leadframe, i.e., the open space 80 extends from the upper surface 44 to the lower surface 46 of the leadframe 40 .
- the leadframe 40 may be constructed from a relatively inexpensive leadframe alloy, for example, the alloy sold under the trade designation “CDA194”.
- the leadframe 40 may be constructed of copper or another copper alloy, other metal or metal alloy.
- tape 90 may be adhered to the lower surface 46 of the leadframe 40 such that it extends beneath the entire extent of the leadframe.
- Tape 90 may include an upper surface 92 and an oppositely disposed lower surface 94 .
- the upper surface 92 of the tape 90 may be adhered to the lower surface 46 of the frame portion 42 in areas where the tape 90 underlies the frame portion 42 .
- the tape 90 may, for example, be either a pressure sensitive adhesive tape or a thermoplastic tape and may have a thickness “A”, for example, of about 2 mil-50 ⁇ m. It is noted that the relative thickness of the tape 90 has been exaggerated in FIG. 5 for purposes of illustrative clarity.
- a shunt 100 may be inserted into the open space 80 of the leadframe 40 .
- the shunt 100 may be located such that it does not touch any part of the leadframe frame portion 42 and is supported only by the tape 90 .
- the shunt 100 may be placed within the open space 80 of the leadframe 40 using conventional die mount, pick and place equipment. It is noted that the shunt 100 may be formed in a large sheet of interconnected shunts (not shown). The shunts may then be separated from one another prior to insertion into the leadframes.
- the shunt 100 may, for example, be formed from a relatively expensive material such as a copper alloy sold under the trademark MANGANIN®. The shunt may be pre-plated or post-plated, as desired.
- an integrated circuit device 110 may be mounted to the leadframe 40 , as shown. More specifically, the Integrated circuit device 110 can be attached to the die mounting pad 70 in a conventional manner, using an adhesive material such as epoxy or silver filled epoxy.
- the integrated circuit device 110 may be electrically connected to the shunt 100 and the leadframe 40 , for example, using bonding wires.
- Bonding wires 102 and 104 may extend between the shunt 100 and the pads 112 and 114 , respectively, on the integrated circuit device 110 .
- a bonding wire 106 may extend between the integrated circuit device pad 116 and the top of the leadframe tab 56 .
- a bonding wire 108 may extend between the integrated circuit device pad 118 and the top of the leadframe tab 58 .
- FIG. 6 only four bonding wires have been shown in FIG. 6 . It is to be understood, however, that many more bonding wires may be provided to establish the desired connections between the integrated circuit device 110 , the leadframe 40 and shunt 100 .
- the leadframe 40 , integrated circuit device 110 and shunt 100 may be encapsulated within a molding material (e.g., the molding material 122 , FIG. 8 ) in a conventional manner.
- the molding material may, for example, be a plastic material such as epoxy or other conventional insulating material.
- the molding material 122 may be formed in an injection molding process or it may be applied as a coating.
- the tape 90 may be removed from the leadframe 40 .
- the individual leadframes in the leadframe sheet 22 may be separated into individual integrated circuit packages, such as the integrated circuit package 120 , FIG. 8 .
- the tabs 50 may be electrically isolated from one another in a conventional manner.
- FIG. 8 schematically illustrates the completed integrated circuit package 120 after encapsulation and separation have been completed, in a manner as described above .
- the molding material 122 may encompass the leadframe 40 , the shunt 100 and the integrated circuit device 110 , except for the bottom 101 of the shunt 100 , the bottom 111 of the die pad and the bottoms of the tabs 50 (e.g., the bottoms 156 , 158 , and 162 of the tabs 56 , 58 , and 62 , respectively). These areas are left exposed (i.e., not covered by the molding material 122 ) in order to facilitate later soldering to an underlying printed circuit board or the like.
- Use of the tape 90 serves to prevent molding material from covering these surfaces during the encapsulation process.
- the bottoms of the tabs 50 facilitate later solder connection of the integrated circuit package 120 to corresponding pads on an underlying printed circuit board or the like.
- a distinct electrical pathway will be established from each pad on the integrated circuit device 110 (e.g., one of the integrated circuit device pads 112 , 114 , 116 , 118 , FIG. 6 ) and a corresponding pad on the printed circuit board.
- FIG. 9 is a flowchart illustrating an exemplary method of manufacturing described herein.
- step 202 includes providing a sheet 22 ( FIGS. 1-2 ) containing a plurality of interconnected leadframes 30 , each leadframe (e.g., the leadframe 40 , FIG. 3 ) having a die mounting pad 70 and an open space 80 extending therethrough.
- Step 204 includes applying tape 90 ( FIGS. 5-6 ) to a lower surface of the leadframes 30 .
- Step 206 encompasses providing a shunt sheet containing a plurality of interconnected shunts (e.g., the shunt 100 , FIG. 6 ).
- Step 208 includes separating the shunt sheet into individual shunts (e.g., the shunt 100 , FIG. 6 ).
- Step 210 describes, using a pick and place apparatus, installing one shunt 100 ( FIG. 6 ) into the open space 80 of each leadframe 40 , such that the shunt 100 is supported on the tape 90 and does not touch any portion of the leadframe 40 .
- Step 212 includes, using a pick and place apparatus, mounting an integrated circuit device 110 ( FIG. 6 ) onto the die mounting pad 70 of each leadframe.
- Step 214 includes wirebonding the integrated circuit device 110 to portions of the leadframe 40 and to the shunt 100 ( FIG. 6 ).
- Step 216 includes encapsulating the leadframe 40 , shunt 100 and integrated circuit device 110 in a molding material 122 ( FIG. 8 ).
- Step 218 encompasses removing the tape 90 from the lower surface of the leadframe 40 .
- step 220 includes separating the individual leadframe units from one another to form a completed integrated circuit package 120 ( FIG. 8 ). This separating step may, for example, be accomplished by a sawing process.
- FIG. 10 is a flowchart depicting one embodiment of a method of manufacturing an integrated circuit package.
- step 302 includes providing at least one lead frame having an upper surface, an oppositely disposed lower surface and at least one open space extending through the at least one leadframe from the upper surface to the lower surface.
- step 304 includes attaching an integrated circuit device to a portion of the upper surface of the at least one leadframe.
- Step 306 includes applying tape to the lower surface of the at least one leadframe.
- Step 308 includes placing a shunt at least partially in the open space such that it is in contact with the tape.
- Step 310 includes electrically connecting the integrated circuit device to the shunt and to the at least one leadframe.
- Step 312 includes encompassing at least portions of the at least one leadframe, the integrated circuit device and the shunt with a molding material.
- step 314 includes, thereafter, removing the tape from the lower surface of the at least one leadframe
- FIG. 11 is a flowchart depicting another embodiment of a method of manufacturing an integrated circuit package.
- step 402 includes providing at least one lead frame having an upper surface, an oppositely disposed lower surface and at least one open space extending through the at least one leadframe from the upper surface to the lower surface.
- step 404 includes attaching an integrated circuit device to a portion of the upper surface of the at least one leadframe.
- Step 406 includes placing a shunt at least partially in the open space such that it is not in contact with any portion of the at least one leadframe.
- Step 408 includes electrically connecting the integrated circuit device to the shunt and to the at least one leadframe.
- step 410 includes, while maintaining the shunt not in contact with any portion of the at least one leadframe, encompassing at least portions of the at least one leadframe, the integrated circuit device and the shunt with a molding material.
- the package and method described herein provide many advantages.
- the present method uses a relatively inexpensive tape 90 to hold the shunt 100 in place within the leadframe.
- Other applications use rivets to hold the shunt in place or tape which ultimately becomes encapsulated and incorporated in the finished device to secure the shunt on the leadframe.
- This type of tape is expensive as it must be die cut to a picture frame form.
- the use of tape in this manner provides additional interfaces where later delamination might occur within the finished package.
- the use of rivets is disadvantageous for several reasons. Riveted attachments, for example, tend to take up more space—particularly since the rivets generally require tie straps extending from the leadframe. Further, a more complex leadframe and shunt result when rivets are used.
- the use of rivets negatively impacts the hermeticity of the overall package since additional paths for moisture ingress are created (i.e., the tie straps to which the rivets attach, one located at each end of the shunt).
- the shunt 100 is fully encapsulated on five sides with only the bottom surface 101 exposed.
- the present package and method also allow customization of the shunt 100 ; the shunt, for example, can be formed from a different alloy than the leadframe 40 and/or the shunt 100 can be selectively plated with any desired material without the need to also plate the leadframe 40 . Further, the size and shape of the shunt 100 can be easily changed with no need to change the configuration of the leadframe 40 (as long as the shunt 100 fits in the leadframe open space 80 ).
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Lead Frames For Integrated Circuits (AREA)
- Wire Bonding (AREA)
Abstract
Description
- An integrated circuit package serves to physically and electrically connect an integrated circuit device (housed within the integrated circuit package) to a printed circuit board. One type of integrated circuit package is known as a “flat no-leads package”. This type of package is a surface-mount technology that connects an integrated circuit device to surfaces of the printed circuit board without the use of through-holes. Perimeter lands on the package bottom provide electrical connections to the printed circuit board. Flat no-leads packages typically include a planar copper leadframe substrate upon which the integrated circuit device is mounted. The leadframe and the integrated circuit device are typically encapsulated within a molding material. Flat no-lead packages generally include an exposed thermal pad to improve heat transfer out of the integrated circuit device (and into the printed circuit board). There are various types of flat no-leads packages in use, including QFN (quad-flat no-leads) and DFN (dual-flat no-leads) variations.
- For certain integrated circuit package applications, it is required that a rectangular copper alloy slug or shunt be included in the package with one surface exposed for soldering.
-
FIG. 1 is a plan view of exemplary block of connected leadframe sheets. -
FIG. 2 is a plan view of one of the leadframe sheets ofFIG. 1 . -
FIG. 3 is a plan view of an exemplary leadframe from the leadframe sheet ofFIG. 2 . -
FIG. 4 is a cross-section view of the leadframe ofFIG. 3 , taken along the line 4-4 inFIG. 3 . -
FIG. 5 is a cross-section view similar to that ofFIG. 4 , but showing the leadframe ofFIG. 3 having tape applied to its lower surface. -
FIG. 6 is a plan view of the leadframe ofFIG. 3 , illustrating a shunt supported on the tape shown inFIG. 5 , an integrated circuit device mounted on a die pad of the leadframe and wirebonding between the integrated circuit device, the shunt and the leadframe. -
FIG. 7 is a cross-section view of the leadframe ofFIG. 6 , taken along the line 7-7 inFIG. 6 . -
FIG. 8 is a perspective view of a completed integrated circuit package. -
FIG. 9 illustrates by flow diagram, selected steps in an exemplary method for manufacturing an integrated circuit package according to the present disclosure. -
FIG. 10 illustrates by flow diagram, one embodiment of a method of manufacturing an integrated circuit package. -
FIG. 11 illustrates by flow diagram, another embodiment of a method of manufacturing an integrated circuit package. - As discussed previously, for certain integrated circuit package applications, it is required that a rectangular copper alloy slug or shunt be included in the package with one surface exposed for soldering. The copper alloy used in the shunt may, for example, be of the type sold under the trademark MANGANIN®, and may, for example, have a composition of about 86% copper, 12% manganese, and 2% nickel. Because of the relatively high cost of this alloy, it is advantageous to have the leadframe formed from a less expensive leadframe alloy, for example, the alloy sold under the trade designation “CDA194”. CDA194 is well suited and characterized both thermally and mechanically for use in leadframes. It is also formulated to facilitate stamping and etching of leadframes.
- In general terms, an integrated circuit package, along with a method of manufacturing the package, are disclosed herein. The disclosed package and method of manufacture provide the ability, for example, to incorporate a slug or shunt made of a more expensive copper alloy (e.g., MANGANIN®) into a package having its leadframe manufactured from a less expensive leadframe alloy. The alloy CDA194, as mentioned above, is widely used for leadframes and is readily available from rolling mills. MANGANIN®, however, is generally less widely used and available.
- The process of manufacturing the package disclosed herein begins by providing a leadframe, e.g., the
leadframe 40,FIG. 3 .FIG. 1 illustrates ablock 10 of connectedleadframe sheets FIG. 2 illustrates theleadframe sheet 22 in further detail, it being understood that theremaining leadframe sheets leadframe sheet 22. With reference toFIG. 2 , theleadframe sheet 22 may include a plurality (e.g., eighty-eight, as depicted inFIG. 2 ) ofleadframes 30 including theindividual leadframes -
FIG. 3 illustrates theleadframe 40 in further detail, it being understood that the remainder of theleadframes 30 may be substantially identical to theleadframe 40. It is noted that, for purposes of illustrative efficiency, the package and method of manufacture will be described herein specifically in conjunction with theexemplary leadframe 40. It is to be understood, however, that the methodology described may be carried out on all of theleadframes 30 while they are still connected to one another in theleadframe sheet 22 and while theleadframe sheets leadframe block 10. - With reference now to
FIG. 3 , theleadframe 40 may include aframe portion 42 having anupper surface 44 and an oppositely disposed lower surface 46 (FIG. 4 ). A plurality oftabs 50, including theindividual tabs frame 42, as shown. The tops of thetabs 50 are the targets for wire bonding connections to the integrated circuit device (in a manner that will be described in further detail herein). With reference again toFIG. 3 , the right side (as viewed in the orientation ofFIG. 3 ) of theleadframe 40 may be occupied by adie mounting pad 70 for mounting an integrated circuit device, in a manner as will be described in further detail herein. The left side of theleadframe 40 may include anopen space 80 that extends completely through the leadframe, i.e., theopen space 80 extends from theupper surface 44 to thelower surface 46 of theleadframe 40. - The
leadframe 40 may be constructed from a relatively inexpensive leadframe alloy, for example, the alloy sold under the trade designation “CDA194”. Alternatively, theleadframe 40 may be constructed of copper or another copper alloy, other metal or metal alloy. - Continuing with the description of the methodology, and with reference now to
FIG. 5 ,tape 90 may be adhered to thelower surface 46 of theleadframe 40 such that it extends beneath the entire extent of the leadframe.Tape 90 may include anupper surface 92 and an oppositely disposedlower surface 94. To adhere thetape 90 to theleadframe 40, theupper surface 92 of thetape 90 may be adhered to thelower surface 46 of theframe portion 42 in areas where thetape 90 underlies theframe portion 42. Thetape 90 may, for example, be either a pressure sensitive adhesive tape or a thermoplastic tape and may have a thickness “A”, for example, of about 2 mil-50 μm. It is noted that the relative thickness of thetape 90 has been exaggerated inFIG. 5 for purposes of illustrative clarity. - With reference to
FIGS. 6 and 7 , after thetape 90 has been applied, ashunt 100 may be inserted into theopen space 80 of theleadframe 40. As can be appreciated fromFIG. 6 , theshunt 100 may be located such that it does not touch any part of theleadframe frame portion 42 and is supported only by thetape 90. Theshunt 100 may be placed within theopen space 80 of theleadframe 40 using conventional die mount, pick and place equipment. It is noted that theshunt 100 may be formed in a large sheet of interconnected shunts (not shown). The shunts may then be separated from one another prior to insertion into the leadframes. Theshunt 100 may, for example, be formed from a relatively expensive material such as a copper alloy sold under the trademark MANGANIN®. The shunt may be pre-plated or post-plated, as desired. - With further reference to
FIGS. 6 and 7 , anintegrated circuit device 110 may be mounted to theleadframe 40, as shown. More specifically, theIntegrated circuit device 110 can be attached to thedie mounting pad 70 in a conventional manner, using an adhesive material such as epoxy or silver filled epoxy. - Next, with continued reference to
FIGS. 6 and 7 , theintegrated circuit device 110 may be electrically connected to theshunt 100 and theleadframe 40, for example, using bonding wires.Bonding wires shunt 100 and thepads circuit device 110. Abonding wire 106 may extend between the integratedcircuit device pad 116 and the top of theleadframe tab 56. In a similar manner, abonding wire 108 may extend between the integratedcircuit device pad 118 and the top of theleadframe tab 58. For purposes of illustrative clarity, only four bonding wires have been shown inFIG. 6 . It is to be understood, however, that many more bonding wires may be provided to establish the desired connections between theintegrated circuit device 110, theleadframe 40 andshunt 100. - After wire bonding has been completed, in a manner as described above, the
leadframe 40, integratedcircuit device 110 and shunt 100 may be encapsulated within a molding material (e.g., themolding material 122,FIG. 8 ) in a conventional manner. The molding material may, for example, be a plastic material such as epoxy or other conventional insulating material. Themolding material 122 may be formed in an injection molding process or it may be applied as a coating. - Once the molding material has been applied and it has hardened, it serves to secure the location of the
shunt 100 relative to theleadframe 40. Accordingly, after the encapsulation step has been completed, thetape 90 may be removed from theleadframe 40. Thereafter, the individual leadframes in theleadframe sheet 22 may be separated into individual integrated circuit packages, such as theintegrated circuit package 120,FIG. 8 . After encapsulation and separation have been completed, in a manner as described above, thetabs 50 may be electrically isolated from one another in a conventional manner. -
FIG. 8 schematically illustrates the completedintegrated circuit package 120 after encapsulation and separation have been completed, in a manner as described above . As can be seen fromFIG. 8 , themolding material 122 may encompass theleadframe 40, theshunt 100 and theintegrated circuit device 110, except for the bottom 101 of theshunt 100, thebottom 111 of the die pad and the bottoms of the tabs 50 (e.g., thebottoms tabs tape 90, in a manner as previously described herein, serves to prevent molding material from covering these surfaces during the encapsulation process. - The bottoms of the tabs 50 (e.g., the
bottoms tabs integrated circuit package 120 to corresponding pads on an underlying printed circuit board or the like. As can be appreciated, once theintegrated circuit package 120 has been attached, for example, to an underlying printed circuit board, a distinct electrical pathway will be established from each pad on the integrated circuit device 110 (e.g., one of the integratedcircuit device pads FIG. 6 ) and a corresponding pad on the printed circuit board. With reference, for example, to thetab 58, electrical continuity will be established between the corresponding printed circuit board pad and thetab 58 via a solder joint extending between the printed circuit board pad and the bottom 158 of the electricallyconductive tab 58. Continuity is also established between the top of thetab 58 and thepad 118 of the integrated circuit device via thebonding wire 108. Accordingly, in this manner, a continuous and distinct electrical pathway is established between thepad 118 of theintegrated circuit device 110 and a corresponding pad on the underlying printed circuit board. -
FIG. 9 is a flowchart illustrating an exemplary method of manufacturing described herein. With reference now toFIG. 9 ,step 202 includes providing a sheet 22 (FIGS. 1-2 ) containing a plurality ofinterconnected leadframes 30, each leadframe (e.g., theleadframe 40,FIG. 3 ) having a die mountingpad 70 and anopen space 80 extending therethrough. Step 204 includes applying tape 90 (FIGS. 5-6 ) to a lower surface of theleadframes 30. Step 206 encompasses providing a shunt sheet containing a plurality of interconnected shunts (e.g., theshunt 100,FIG. 6 ). Step 208 includes separating the shunt sheet into individual shunts (e.g., theshunt 100,FIG. 6 ). Step 210 describes, using a pick and place apparatus, installing one shunt 100 (FIG. 6 ) into theopen space 80 of eachleadframe 40, such that theshunt 100 is supported on thetape 90 and does not touch any portion of theleadframe 40. Step 212 includes, using a pick and place apparatus, mounting an integrated circuit device 110 (FIG. 6 ) onto thedie mounting pad 70 of each leadframe. Step 214 includes wirebonding theintegrated circuit device 110 to portions of theleadframe 40 and to the shunt 100 (FIG. 6 ). Step 216 includes encapsulating theleadframe 40,shunt 100 andintegrated circuit device 110 in a molding material 122 (FIG. 8 ). Step 218 encompasses removing thetape 90 from the lower surface of theleadframe 40. Finally,step 220 includes separating the individual leadframe units from one another to form a completed integrated circuit package 120 (FIG. 8 ). This separating step may, for example, be accomplished by a sawing process. -
FIG. 10 is a flowchart depicting one embodiment of a method of manufacturing an integrated circuit package. With reference now toFIG. 10 ,step 302 includes providing at least one lead frame having an upper surface, an oppositely disposed lower surface and at least one open space extending through the at least one leadframe from the upper surface to the lower surface. Step 304 includes attaching an integrated circuit device to a portion of the upper surface of the at least one leadframe. Step 306 includes applying tape to the lower surface of the at least one leadframe. Step 308 includes placing a shunt at least partially in the open space such that it is in contact with the tape. Step 310 includes electrically connecting the integrated circuit device to the shunt and to the at least one leadframe. Step 312 includes encompassing at least portions of the at least one leadframe, the integrated circuit device and the shunt with a molding material. Finally,step 314 includes, thereafter, removing the tape from the lower surface of the at least one leadframe -
FIG. 11 is a flowchart depicting another embodiment of a method of manufacturing an integrated circuit package. With reference now toFIG. 11 ,step 402 includes providing at least one lead frame having an upper surface, an oppositely disposed lower surface and at least one open space extending through the at least one leadframe from the upper surface to the lower surface. Step 404 includes attaching an integrated circuit device to a portion of the upper surface of the at least one leadframe. Step 406 includes placing a shunt at least partially in the open space such that it is not in contact with any portion of the at least one leadframe. Step 408 includes electrically connecting the integrated circuit device to the shunt and to the at least one leadframe. Finally,step 410 includes, while maintaining the shunt not in contact with any portion of the at least one leadframe, encompassing at least portions of the at least one leadframe, the integrated circuit device and the shunt with a molding material. - As can be appreciated, the package and method described herein provide many advantages. The present method, for example, uses a relatively
inexpensive tape 90 to hold theshunt 100 in place within the leadframe. Other applications use rivets to hold the shunt in place or tape which ultimately becomes encapsulated and incorporated in the finished device to secure the shunt on the leadframe. This type of tape is expensive as it must be die cut to a picture frame form. Further, the use of tape in this manner provides additional interfaces where later delamination might occur within the finished package. The use of rivets is disadvantageous for several reasons. Riveted attachments, for example, tend to take up more space—particularly since the rivets generally require tie straps extending from the leadframe. Further, a more complex leadframe and shunt result when rivets are used. Most significantly, the use of rivets negatively impacts the hermeticity of the overall package since additional paths for moisture ingress are created (i.e., the tie straps to which the rivets attach, one located at each end of the shunt). In the present process using thetape 90, theshunt 100 is fully encapsulated on five sides with only thebottom surface 101 exposed. - Another advantage provided by the package and method described herein is that, since the
tape 90 is removed after encapsulation, it does not become part of the final package and, thus, does not pose a risk of causing delamination between the mold compound and the tape. The present package and method also allow customization of theshunt 100; the shunt, for example, can be formed from a different alloy than theleadframe 40 and/or theshunt 100 can be selectively plated with any desired material without the need to also plate theleadframe 40. Further, the size and shape of theshunt 100 can be easily changed with no need to change the configuration of the leadframe 40 (as long as theshunt 100 fits in the leadframe open space 80). - The foregoing description of specific embodiments has been presented for purposes of illustration and description. The specific embodiments described are not intended to be exhaustive or to suggest a constraint to the precise forms disclosed, and many modifications and variations are possible in light of the above teaching. The illustrated embodiments were chosen and described in order to best explain principles and practical application, to thereby enable others skilled in the art to best utilize the various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure herein be defined only by the claims appended hereto and their equivalents, except as limited by the prior art.
Claims (20)
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US13/644,647 US8697496B1 (en) | 2012-10-04 | 2012-10-04 | Method of manufacture integrated circuit package |
US14/189,874 US20140175626A1 (en) | 2012-10-04 | 2014-02-25 | Integrated circuit package and method of manufacture |
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US13/644,647 US8697496B1 (en) | 2012-10-04 | 2012-10-04 | Method of manufacture integrated circuit package |
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US14/189,874 Division US20140175626A1 (en) | 2012-10-04 | 2014-02-25 | Integrated circuit package and method of manufacture |
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US8697496B1 US8697496B1 (en) | 2014-04-15 |
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US14/189,874 Abandoned US20140175626A1 (en) | 2012-10-04 | 2014-02-25 | Integrated circuit package and method of manufacture |
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US14/189,874 Abandoned US20140175626A1 (en) | 2012-10-04 | 2014-02-25 | Integrated circuit package and method of manufacture |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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US9704812B1 (en) * | 2016-05-06 | 2017-07-11 | Atmel Corporation | Double-sided electronic package |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
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US10365303B2 (en) | 2016-04-28 | 2019-07-30 | Texas Instruments Incorporated | Shunt strip |
US20170323708A1 (en) | 2016-05-03 | 2017-11-09 | Texas Instruments Incorporated | Component sheet and method of singulating |
US10335875B2 (en) | 2016-05-26 | 2019-07-02 | Texas Instruments Incorporated | Methods and devices for dicing components from a sheet of copper alloy |
CN111128944B (en) * | 2019-12-30 | 2021-12-10 | 南通南平电子科技有限公司 | High-performance capacitor lead frame |
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US7005325B2 (en) * | 2004-02-05 | 2006-02-28 | St Assembly Test Services Ltd. | Semiconductor package with passive device integration |
US7847391B2 (en) * | 2008-07-01 | 2010-12-07 | Texas Instruments Incorporated | Manufacturing method for integrating a shunt resistor into a semiconductor package |
US8963305B2 (en) * | 2012-09-21 | 2015-02-24 | Freescale Semiconductor, Inc. | Method and apparatus for multi-chip structure semiconductor package |
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- 2012-10-04 US US13/644,647 patent/US8697496B1/en active Active
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2014
- 2014-02-25 US US14/189,874 patent/US20140175626A1/en not_active Abandoned
Cited By (1)
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US9704812B1 (en) * | 2016-05-06 | 2017-07-11 | Atmel Corporation | Double-sided electronic package |
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US8697496B1 (en) | 2014-04-15 |
US20140175626A1 (en) | 2014-06-26 |
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