FIELD

The present invention is directed to apparatuses and methods for low profile integrated circuits. In particular, the present invention is directed to semiconductor packaging that allows both front side and back side attachment to an internal substrate.

BACKGROUND

A semiconductor package is a metal, plastic, glass, or ceramic casing containing one or more discrete semiconductor devices or integrated circuits. Semiconductor dice are fabricated on semiconductor wafers (commonly silicon) before being diced into die, tested, and packaged. The package provides a means for connecting a die or dice to the external environment, such as a printed circuit board, via leads such as lands, balls, or pins; and protected against threats such as mechanical impact, chemical contamination, and light exposure. Additionally, the semiconductor package helps dissipate heat produced by the die, with or without the aid of a heat spreader. There are thousands of package types in current use. Some may be defined by international, national, or industry standards, while others are particular to an individual manufacturer. A semiconductor package may have as few as two leads or contacts for devices such as diodes, or in the case of advanced microprocessors, a package may have hundreds of connections. Very small packages may be supported only by their wire leads. Larger devices, intended for high-power applications, may be installed in carefully designed heat sinks so that they can dissipate hundreds or thousands of watts of heat.

Semiconductor packages may be molded out of an epoxy plastic that provides adequate protection of the semiconductor devices and mechanical strength to support the leads and handling of the package. Some devices, intended for high-reliability or aerospace or radiation environments, may use ceramic packages, with metal lids that are brazed on after assembly, or a glass frit seal. All-metal packages may be often used with high power (several watts or more) devices, since they conduct heat well and allow for easy assembly to a heat sink. Lead materials may bet be chosen with a thermal coefficient of expansion to match the package material.

Package materials for high-density dynamic memory may be selected for low background radiation; a single alpha particle emitted by package material may cause a single event upset and transient memory errors (soft errors). Spaceflight and military applications traditionally use hermetically packaged microcircuits. Many modern integrated circuits may only be available as plastic encapsulated microcircuits (PEMs). In addition to providing connections to the semiconductor and handling excess heat, the semiconductor package must protect the die and other components from the environment, particularly the ingress of moisture. Stray particles or corrosion products inside the package may degrade performance of the device or cause failure. A hermetic package allows essentially no gas exchange with the surroundings; such construction may require glass, ceramic, or metal enclosures.

SUMMARY

In accordance with an embodiment of the present invention, a device is provided. The device may include one or more of a package base, a substrate, a die secured to the substrate, a plurality of bond connections, and a package lid. The package base includes a plurality of package leads and a package base body. The package base body includes an open cavity disposed through the entire package base body, a plurality of package bond pads, disposed within a periphery of the open cavity, and a mounting shelf, disposed within the open cavity. The substrate is secured to the mounting shelf, and includes a plurality of substrate bond pads. The plurality of bond connections are configured to provide electrical connections between one or more of the die, the substrate bond pads, and the package bond pads. The package lid is secured over the open cavity to the package base body.

In accordance with another embodiment of the present invention, a method is provided. The method may include bonding a die to a front side of a substrate. In response to bonding the die to the substrate, the method may include one or more of bonding the substrate to a mounting shelf within a cavity of a package base, providing bond connections between one or more of the die, the substrate, and package bond pads of the package base, and sealing a lid over the cavity to a top surface of the package base. The front side of the substrate faces the lid, and the cavity extends through a height of the entire package base.

In accordance with yet another embodiment of the present invention, a method is provided. The method may include bonding a substrate to a mounting shelf within a cavity of a package base. In response to bonding the substrate to the mounting shelf, the the method may include one or more of bonding a die to a front side of the substrate, providing bond connections between one or more of the die, the substrate, and package bond pads of the package base, and sealing a lid over the cavity to a top surface of the package base. The front side of the substrate faces the lid, and the cavity extends through a height of the entire package base.

An advantage of the present invention is it provides both top side (i.e. internal) and bottom side (i.e. external) build-up within a low profile package. This provides very high density custom circuits within an existing package pinout, which may facilitate functional replication of an out-of-production integrated circuit.

Another advantage of the present invention is it can provide a hermetic environment for a complex custom circuit. A top side of a substrate may be packaged in a hermetic environment, where one or more dies and components are environmentally protected by a hermetic package base, hermetic package lid, hermetic lid seal, hermetic substrate, hermetic die attach adhesive, etc. A hermetic component, such as a ball grid array or flip-chip, may be bonded to an underside of the substrate and still maintain hermeticity for the entire device.

Another advantage of the present invention is it can provide a non-hermetic environment for a complex custom circuit. An inexpensive package base such as plastic may be used in conjunction with an inexpensive FR-4 printed circuit board as a substrate. In lieu of a package lid, an inexpensive encapsulant material may fill the open cavity and capture any bond wires used during the packaging process.

Yet another advantage of the present invention is it provides a flexible custom circuit for any type of thru hole or surface mount meta-package. DIP, PGA, SIP, QFP, etc packages are all supported. This allows an existing meta-package footprint on an existing assembly to be maintained without requiring redesign of an assembly using the meta-package.

Additional features and advantages of embodiments of the present invention will become more readily apparent from the following description, particularly when taken together with the accompanying drawings.

