National Semiconductor Corporation

Peter Howard Spalding

Jaime A Bayan

Santhiran Nadarajah

Chan Peng Yeen

Sharon Ko Mei Wan

Harry Kam Cheng Hong

Hu Ah Lek

Ah Lek Hu

Sharon Mei Wan Ko

Yin Yen Bong

Aik Seng Kang

Chin Seng Chu

Harry Cheng Hong Kam

Hem P Takiar

Uli H Hegel

James L Crozier

Ka-Heng The

Michelle M Hou-Chang

Martin A Delateur

Charlie Kho Chua

Harry Cheng-Hong Kam

A panel assembly of packaged integrated circuit devices including a conductive substrate panel having an array of device areas and a plurality of locking passageways. The locking passageways are positioned about an inactive buffer area which surrounds the periphery of the array of device areas. The panel assembly also includes a molded cap that is molded over the topside of the panel to encapsulate the array of device areas and the inactive buffer area. The molded cap includes conforming locking stem portions that extend into each of the locking passageways in a manner locking the molded cap to the substrate panel such that during singulation of the device areas, the molded cap will not separate from the substrate panel at the inactive buffer area. In another aspect of the invention, a method for producing the panel assembly having the locking passageways is described.

Locking of mold compound to conductive substrate panels

A leadless leadframe semiconductor package having a plurality of contacts, which have contact surfaces on the bottom surface of the package. At least some of the contacts have integrally formed stems that extend outward to the peripheral surface of the package. These stems have heights and widths less than the heights and widths of their corresponding contacts. A molded cap encapsulates at least a portion of the die, the stems and the contacts. Another aspect of the invention pertains to a leadless leadframe panel assembly having a conductive substrate panel that has at least one array of device areas, each array of device areas having a plurality of tie bars and a plurality of contacts. The contacts also have integrally formed stems that extend towards and connect to one of the tie bars. The stems have widths and heights that are less than the widths and heights of their corresponding contacts.

Leadless leadframe package design that provides a greater structural integrity

A leadless leadframe semiconductor package includes a plurality of contacts, at least some of which have integrally formed stems that extend to the peripheral surface of the package. These stems have heights and widths less than the heights and widths of their corresponding contacts. A molded cap encapsulates the stems and the contacts to leave contact surfaces of the contacts exposed on the bottom surface of the package. Another aspect of the invention pertains to a leadless leadframe panel assembly having a conductive substrate panel that has at least one array of device areas, which has a plurality of tie bars and a plurality of contacts. The contacts have integrally formed stems that extend towards and connect to one of the tie bars. The stems have widths and heights that are less than the widths and heights of their corresponding contacts.

A panel assembly of packaged integrated circuit devices comprising a conductive substrate panel having an array of device areas and a plurality of locking passageways. The locking passageways are positioned about an inactive buffer area which surrounds the periphery of the array of device areas. The locking passageways extend from a topside of the panel toward a bottom side of the panel. The panel assembly also includes a molded cap that is molded over the topside of the panel to encapsulate the array of device areas and the inactive buffer area. The molded cap includes conforming locking stem portions that extend into each of the locking passageways in a manner locking the molded cap to the substrate panel such that during singulation of the device areas, the molded cap will not separate from the substrate panel at the inactive buffer area. In another aspect of the invention, a method for producing the panel assembly having the locking passageways is described. The method involves providing a conductive substrate panel having the locking passageways and applying molding material to the topside of the substrate panel such that the solidified molding material forms stems that conform to the passageways.

An assembly and method suitable for use in packaging integrated circuits including a support substrate for supporting an integrated circuit die embedded in a molded encapsulating cap. The substrate includes a conductive die attach pad adapted to be molded into the encapsulating cap. The pad includes an interior facing support surface and a spaced-apart exterior facing exposed surface defined by a peripheral edge. The support surface is adapted to support the embedded die, while the exposed surface is to be exposed from the encapsulating cap. The attach pad further includes a locking ledge portion extending outward peripherally beyond at least a portion of the exposed surface peripheral edge. This ledge is adapted to be subtended in the encapsulating cap in a manner substantially preventing a pull-out of the attach pad in a direction away from the encapsulating cap.

Locking lead tips and die attach pad for a leadless package apparatus and method

A leadless leadframe semiconductor package comprising a plurality of contacts, which have contact surfaces on the bottom surface of the package. At least some of the contacts have integrally formed stems that extend outward to the peripheral surface of the package. These stems have heights and widths less than the heights and widths of their corresponding contacts. A molded cap encapsulates at least a portion of the die, the stems and the contacts. The molded cap leaves the contact surfaces of the contacts exposed on the bottom surface of the package, leaves a peripheral surface of the stems exposed on the peripheral surface of the package, and covers a bottom surface of each of the stems. Another aspect of the invention pertains to a leadless leadframe panel assembly having a conductive substrate panel that has at least one array of device areas, each array of device areas having a plurality of tie bars and a plurality of contacts. The contacts have contact surfaces on the bottom surface of the leadless leadframe panel assembly. The contacts also have integrally formed stems that extend towards and connect to one of the tie bars. The stems have widths and heights that are less than the widths and heights of their corresponding contacts. A molded cap encapsulates at least a portion of each die, the tie bars, the stems and the contacts while leaving the contact surfaces of the contacts exposed and covering a bottom surface of each of the stems.

A leadless leadframe panel comprising a partially etched top surface of a substrate panel that forms recessed regions that define a portion of a first and a second set of tie bars and a portion of a first and second set of contact pads. A bottom surface of the panel forms lower recessed regions that define the remaining portion of the first and second set of tie bars and the remaining portion of the first and second set of contact pads. The resulting contact pads are connected to a respective one of the tie bars.

Multiple row fine pitch leadless leadframe package with use of half-etch process

A packaging arrangement is described that utilizes a conductive panel (such as a leadless leadframe) as its base. The conductive panel has a matrix of device areas that each include a plurality of rows of contacts that are located outside of a die area. Tie bars provide support for the various contacts. Some of the tie bars are arranged to extend between adjacent contacts in the same row and some of the tie bars are arranged to extend diagonally between associated contacts in adjacent rows that are not adjacent one another. During packaging, the tie bars can be severed by cutting along lines (e.g. saw streets) that run adjacent the rows after a molding operation. The described panels are particularly useful in packages having three or more rows of contacts.

Multi row leadless leadframe package

A panel assembly of packaged integrated circuit devices including conductive substrate panel having an array of device areas and a plurality of locking passageways. The locking passageways are positioned about an inactive buffer area which surrounds the periphery of the array of device areas. The locking passageways extend from a topside of the panel toward a bottom side of the panel. The panel assembly also includes a molded cap that is molded over the topside of the panel to encapsulate the array of device areas and the inactive buffer area. The molded cap includes conforming locking stem portions that extend into each of the locking passageways in a manner locking the molded cap to the substrate panel such that during singulation of the device areas, the molded cap will not separate from the substrate panel at the inactive buffer area. In another aspect of the invention, a method for producing the panel assembly having the locking passageways is described. The method involves providing a conductive substrate panel having the locking passageways and applying molding material to the topside of the substrate panel such that the solidified molding material forms stems that conform to the passageways.

An off-loading system comprising an array of suction tubes which are each able to pick up an associated semiconductor device from the matrix of devices and a pump which pulls air through the suction tubes to create a sufficiently low pressure within the suction tubes to allow each suction tube to pick up an associated device. In another embodiment of the invention, the off-loading system also includes a pin board which supports an array of pins configured to raise a selected array of the semiconductor devices to assist in picking up the selected array of devices from the matrix of devices. Another embodiment of the invention includes a rack that includes multiple elongated rails which form multiple channels through which the semiconductor devices travel so that they may properly enter a subsequent phase of the manufacturing process. Another aspect of the invention pertains to a method for transporting semiconductor devices from a matrix of semiconductor devices during a semiconductor assembly process using the off-loading system of the present invention. The method includes picking up a selected array of semiconductor devices individually and simultaneously from the matrix and depositing at least one of the devices of the selected array onto a handling station. In one embodiment of the method, the selected array of the semiconductor devices are raised relative to the other semiconductor devices in the matrix in order to assist in picking up the selected array of packaged devices from the matrix.

Off-load system for semiconductor devices

A semiconductor device exhibiting a lower incidence of burrs forming on its contacts during the singulation process. The semiconductor device includes a die which is electrically connected to a set of contacts wherein each contact has a contact surface and a non-contact surface. Each contact surface of the contacts contains a recessed region filled with a first deposit of molding material. The die and the non-contact surfaces of the contacts are encapsulated with a second deposit of molding material. The semiconductor device is singulated from a molded lead frame by guiding a saw blade through recessed regions formed on the contact surface of the contacts. The molding material in the recessed regions creates a &ldquo;buffer zone&rdquo; which separates the path of the saw blade from the contact surface of the contacts. As a result, the formation of burrs is reduced because the sides of the saw blade are no longer in contact with the contact surface and are therefore unable to pull the contact surface into a burr formation. The molding material also prevents the contact material at the bottom of the recessed region, on the newly cut surface of the contact, from being pulled above the contact surface of the contact. The molding material in the recessed region accomplishes this by acting as a barrier which blocks the movement of contact material which may be pulled.

Lead frame design for burr-free singulation of molded array packages

A variety of leadless packaging arrangements and methods of packaging integrated circuits in leadless packages that are arranged to have relatively low inductance are disclosed. In one aspect, a leadless semiconductor package is described having an exposed die pad and a plurality of exposed contacts that are formed from a common substrate material. The die attach pad, however, is thinned relative to at least a portion of the contacts. A die is mounted on the thinned die attach pad and wire bonded to the contacts. Since the die attach pad is lower than the contact surface being wire bonded to, the length of the bonding wires can be relatively reduced, thereby reducing inductance of the device. A plastic cap is molded over the die and the contacts thereby encapsulating the bonding wires while leaving the bottom surface of the contacts exposed. In some embodiments, the die is arranged to overhangs beyond the die attach pad towards the contacts. In other embodiments, a portion of at least some of the contacts are thinned to a thickness substantially similar to the die attach pad to form contact shelves. The die is then mounted such that it bridges the die attach pad to the contact shelves. In some of the embodiments, reverse wire bonding is used to further shorten the bonding wires. The described devices are packaged in bulk on a conductive substrate panel.

Low inductance leadless package

Pin indicator for leadless leadframe packages

A variety of techniques for electrically debussing conductive substrate panels used in the formation of a matrix of leadless integrated circuit packages are described. Generally, after a matrix of leadless packages have been fabricated in panel form on a conductive substrate panel, tie bars that are used to support contacts and potentially other structures on the conductive substrate are removed after plastic caps have been molded over the matrix, but before separating the packaged devices. This serves to electrically isolate the contacts from one another while leaving sufficient portions of the molded substrate structure in tact to facilitate handling the structure in panel form. With the described arrangement, the packaged devices may be tested in panel form. After testing and any other desired panel based operations, the packaged devices may be separated using conventional techniques. The removal of the tie bars can be accomplished by any suitable technique including, for example, sawing or etching.

Electrical isolation in panels of leadless IC packages

Improved methods of packaging integrated circuits in leadless packages are disclosed. A conductive substrate sheet is initially patterned to form troughs that define a multiplicity of device areas. Each device area includes a plurality of contact landings (and preferably a die attach pad) that are formed in substrate sheet by patterning. The patterning can be done using a variety of conventional techniques including etching. A multiplicity of dice are then attached to the substrate sheet and bond pads on the dice are electrically connected to associated contact landings using conventional techniques such as wire bonding. One or more caps are then molded over the device areas to encapsulate the dice and bonding wires and to fill the troughs. After the caps have been formed, excess portions of the substrate sheet (e.g. portions below the troughs) are removed to electrically isolate the contact landings thereby forming electrically isolated independent contacts in a molded package. In the resulting arrangement, the molding material serves to hold the contacts in place as well as to electrically isolate the independent contacts. The excess substrate material can be removed using a variety of techniques including mechanical grinding and chemical etching and/or a combination of the two. In the described arrangement, the &ldquo;excess&rdquo; substrate material serves to prevent the formation of flash below the contacts during the molding operation. The &ldquo;excess&rdquo; substrate material also supports the die attach pad and the contacts during both wire bonding and the die attach process.

Growing community of inventors

Cupertino, CA, United States of America

Peter Howard Spalding