The present invention relates in general to integrated circuit packaging, and in particular to an improved ball grid array package with enhanced thermal characteristics and a unique method of manufacturing.
High performance integrated circuit (IC) packages are well known in the art. Improvements in IC packages are driven by industry demands for increased thermal and electrical performance and decreased size and cost of manufacture.
In general, array packaging such as Plastic Ball Grid Array (PBGA) packages provide a high density of interconnects relative to the surface area of the package. However, typical PBGA packages include a convoluted signal path, giving rise to high impedance and an inefficient thermal path which results in low thermal dissipation performance. With increasing package density, the spreading of heat generated by the package is increasingly important.
Reference is made to
Variations to conventional BGA packages have been proposed for the purpose of increasing thermal and electrical performance. One particular variation includes the addition of a metal heat spreader to the package, as shown in
It is therefore an object of an aspect of the present invention to provide a process for manufacturing a BGA package that obviates or mitigates at least some of the disadvantages of the prior art.
In one aspect, a process for manufacturing an integrated circuit package is provided. The process includes forming a plurality of solder balls on a first surface of a substrate and mounting a semiconductor die to the substrate such that bumps of the semiconductor die are electrically connected to conductive traces of the substrate. The semiconductor die and the solder balls are encapsulated in an overmold material on the substrate such that portions of the solder balls are exposed. A ball grid array is formed such that bumps of the ball grid array are electrically connected to the conductive traces and the integrated circuit package is singulated.
In another aspect, an integrated circuit package is provided. The package includes a substrate having a plurality of conductive traces and a plurality of solder balls disposed on a first surface of the substrate. A semiconductor die is mounted to the substrate such that bumps of the semiconductor die are electrically connected to conductive traces of the substrate. An overmold material encapsulates the semiconductor die and the solder balls on the substrate such that portions of the solder balls are exposed. A ball grid array is in electrical connection with the conductive traces.
Advantageously, solder balls are embedded in the overmold material. The solder balls provide a heat path for heat dissipation from the package. Also, the solder balls in the overmold material enable package stacking which provides for reduced mother board area when the packages are in use and improves package to package communication signal paths.
In another aspect, bumps of a ball grid array are mounted on solder balls which are encapsulated in overmold material. This package provides better control of solder ball stand off clearance than prior art packages.
Reference is now made to
Referring to
The process for manufacturing the ball grid array package 120, according to one embodiment of the present invention, will now be described in more detail. Referring to
The plurality of solder balls 134 are formed on solder ball pads on the upper surface of the substrate 122 using conventional positioning techniques (
A singulated semiconductor die 124 is conventionally mounted to the upper surface of the substrate 122 using a suitable die attach technique, such as attachment using a die attach epoxy adhesive and curing of the epoxy (
The semiconductor die 124 has a conductive pad array formed thereon and wire bonds 126 are bonded between bumps of the conductive pad array of the semiconductor die 124 and the conductive traces of the substrate 122 using conventional wire bonding techniques (
Encapsulation in the overmold material 128 follows. The semiconductor die 124 and the solder balls 134 are encapsulated in the overmold material 128 by molding in a mold die such that portions of the solder balls 134 that are distal the substrate 122, are exposed. The solder balls 134 are deformed into substantially spheroidal shapes during molding as a result of pressure from the surface of the mold die (
Next, a ball grid array 130 in the form of solder bumps, is formed on the lower surface of the substrate 122 by conventional positioning (
Singulation of the individual BGA unit from the array strip is then performed either by saw singulation or die punching, resulting in the configuration shown in
The BGA package 120 produced by this process is particularly suitable for stacking with other BGA packages, as shown in
Reference is now made to
Reference is now made to
A plurality of solder balls 134 are formed on solder ball pads on the lower surface of the substrate 122 using conventional positioning techniques (
A singulated semiconductor die 124 is conventionally mounted to the lower surface of the substrate 122 using a suitable die attach technique, such as attachment using a die attach epoxy adhesive and curing of the epoxy (
The semiconductor die 124 has a conductive pad array formed thereon and wire bonds 126 are bonded between bumps of the conductive pad array of the semiconductor die 124 and the conductive traces of the substrate 122 using conventional wire bonding techniques (
Encapsulation in the overmold material 128 follows. The semiconductor die 124 and the solder balls 134 are encapsulated in the overmold material 128 by molding in a mold die such that portions of the solder balls 134 that are distal the substrate 122, are exposed. The solder balls 134 are deformed into substantially spheroidal shapes during molding as a result of pressure from the surface of the mold die (
Next, a ball grid array 130 in the form of solder bumps, is formed on the exposed portions of the solder balls 134 by conventional positioning (
Singulation of the individual BGA unit from the array strip is then performed either by saw singulation or die punching, resulting in the configuration shown in
Reference is now made to
The substrate is laminated to a metal strip 140 which acts as a heat spreader for dispersing heat (
A plurality of solder balls 134 are formed on solder ball pads on the exposed lower surface of the substrate 122 using conventional positioning techniques (
A singulated semiconductor die 124 is mounted to the metal strip 140 which is laminated to the substrate 122, using a suitable die attach technique. Thus, the semiconductor die 124 is attached to the substrate 122 via the metal strip 140 (
The semiconductor die 124 has a conductive pad array formed thereon and wire bonds 126 are bonded between bumps of the conductive pad array of the semiconductor die 124 and the conductive traces of the substrate 122 using conventional wire bonding techniques (
Encapsulation in the overmold material 128 follows. The semiconductor die 124 and the solder balls 134 are encapsulated in the overmold material 128 by molding in a mold die such that portions of the solder balls 134 that are distal the substrate 122, are exposed. The solder balls 134 are deformed into substantially spheroidal shapes during molding as a result of pressure from the surface of the mold die (
Next, a ball grid array 130 in the form of solder bumps, is formed on the exposed portions of the solder balls 134 by conventional positioning (
Singulation of the individual BGA unit from the array strip is then performed either by saw singulation or die punching, resulting in the configuration shown in
Reference is now made to
The substrate is laminated to a metal strip 140 that is preplated with suitable metal for ground bonding. Such metal plating includes, for example silver, nickel followed by gold and nickel followed by palladium (
Solder is then applied to the holes of the substrate and the solder is reflowed, followed by a flattening process such as coining to result in a substantially flat surface (
A plurality of solder balls 134 are formed on solder ball pads on the exposed lower surface of the substrate 122 and on the solder in the holes of the substrate 122, using conventional positioning techniques (
A singulated semiconductor die 124 is mounted to the metal strip 140 which is laminated to the substrate 122, using a suitable die attach technique. Thus, the semiconductor die 124 is attached to the substrate 122 via the metal strip 140 (
The semiconductor die 124 has a conductive pad array formed thereon and wire bonds 126 are bonded between bumps of the conductive pad array of the semiconductor die 124 and the conductive traces of the substrate 122 using conventional wire bonding techniques (
Encapsulation in the overmold material 128 follows. The semiconductor die 124 and the solder balls 134 are encapsulated in the overmold material 128 by molding in a mold die such that portions of the solder balls 134 that are distal the substrate 122, are exposed. The solder balls 134 are deformed into substantially spheroidal shapes during molding as a result of pressure from the surface of the mold die (
Next, a ball grid array 130 in the form of solder bumps, is formed on the exposed portions of the solder balls 134 by conventional positioning (
Singulation of the individual BGA unit from the array strip is then performed either by saw singulation or die punching, resulting in the configuration shown in
Next, the area under the semiconductor die 124 is filled with a thermosetting plastic compound, referred to generally as an underfill material 132. The underfill material 132 surrounds the solder ball connections 138 that connect the semiconductor die 124 and the interconnect pads of the substrate 122 (
Alternative embodiments and variations are possible. For example, the packages described herein have been described as being polyimide and BT resin/glass epoxy printed circuit board substrates. However, other substrates may be used such as ceramic substrates and organic laminates. Also, the size and shape of many of the elements described and shown can vary. Still other embodiments and variations may occur to those skilled in the art. All such embodiments and variations are believed to be within the scope and sphere of the present invention.
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