Package on a package (PoP) is an integrated circuit packaging method to vertically combine discrete logic and memory ball grid array (BGA) packages. Two or more packages are installed atop each other, i.e. stacked, with a standard interface to route signals between them. This allows higher component density in devices, such as mobile phones, personal digital assistants (PDA), and digital cameras, at the cost of slightly higher height requirements. Stacks with more than 2 packages are uncommon, due to heat dissipation considerations.
Two widely used configurations exist for PoP:
During PCB assembly, the bottom package of a PoP stack is placed directly on the PCB, and the other package(s) of the stack are stacked on top. The packages of a PoP stack become attached to each other (and to the PCB) during reflow soldering.
The package on a package technique tries to combine the benefits of traditional packaging with the benefits of die-stacking techniques, while avoiding their drawbacks.
Traditional packaging places each die in its own package, a package designed for normal PCB assembly techniques that place each package directly on the PCB side-by-side. The 3D die-stacking system in package (SiP) techniques stacks multiple die in a single package, which has several advantages and also some disadvantages compared to traditional PCB assembly.
In embedded PoP techniques, chips are embedded in a substrate on the bottom of the package. This PoP technology enables smaller packages with shorter electrical connections and is supported by companies such as Advanced Semiconductor Engineering (ASE). [1]
The most obvious benefit is motherboard space savings. PoP uses much less PCB area, almost as little as stacked-die packages.
Electrically, PoP offers benefits by minimizing track length between different interoperating parts, such as a controller and memory. This yields better electrical performance of devices, since shorter routing of interconnections between circuits yields faster signal propagation and reduced noise and cross-talk.
There are several key differences between stacked-die and stacked-package products.
The main financial benefit of package on a package is that the memory device is decoupled from the logic device. Therefore this gives PoP all the same advantages that traditional packaging has over stacked-die products:
Package on a package is also known by other names:
In 2001, a Toshiba research team including T. Imoto, M. Matsui and C. Takubo developed a "System Block Module" wafer bonding process for manufacturing 3D integrated circuit (3D IC) packages. [4] [5] The earliest known commercial use of a 3D package-on-package chip was in Sony's PlayStation Portable (PSP) handheld game console, released in 2004. The PSP hardware includes eDRAM (embedded DRAM) memory manufactured by Toshiba in a 3D package chip with two dies stacked vertically. [6] Toshiba called it "semi-embedded DRAM" at the time, before later calling it a stacked "chip-on-chip" (CoC) solution. [6] [7]
In April 2007, Toshiba commercialized an eight-layer 3D chip package, the 16 GB THGAM embedded NAND flash memory chip, which was manufactured with eight stacked 2 GB NAND flash chips. [8] The same month, U.S. patent 7,923,830 ("Package-on-package secure module having anti-tamper mesh in the substrate of the upper package") was filed by Steven M. Pope and Ruben C. Zeta of Maxim Integrated. [9] In September 2007, Hynix Semiconductor introduced 24-layer 3D packaging technology, with a 16 GB flash memory chip that was manufactured with 24 stacked NAND flash chips using a wafer bonding process. [10]
Computer memory stores information, such as data and programs, for immediate use in the computer. The term memory is often synonymous with the terms RAM,main memory or primary storage. Archaic synonyms for main memory include core and store.
An integrated circuit (IC), also known as a microchip, computer chip, or simply chip, is a small electronic device made up of multiple interconnected electronic components such as transistors, resistors, and capacitors. These components are etched onto a small piece of semiconductor material, usually silicon. Integrated circuits are used in a wide range of electronic devices, including computers, smartphones, and televisions, to perform various functions such as processing and storing information. They have greatly impacted the field of electronics by enabling device miniaturization and enhanced functionality.
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A system in a package (SiP) or system-in-package is a number of integrated circuits (ICs) enclosed in one chip carrier package or encompassing an IC package substrate that may include passive components and perform the functions of an entire system. The ICs may be stacked using package on package, placed side by side, and/or embedded in the substrate. The SiP performs all or most of the functions of an electronic system, and is typically used when designing components for mobile phones, digital music players, etc. Dies containing integrated circuits may be stacked vertically on the package substrate. They are internally connected by fine wires that are bonded to the package substrate. Alternatively, with a flip chip technology, solder bumps are used to join stacked chips together and to the package substrate, or even both techniques can be used in a single package. SiPs are like systems on a chip (SoCs) but less tightly integrated and not on a single semiconductor die.
The transistor count is the number of transistors in an electronic device. It is the most common measure of integrated circuit complexity. The rate at which MOS transistor counts have increased generally follows Moore's law, which observes that transistor count doubles approximately every two years. However, being directly proportional to the area of a chip, transistor count does not represent how advanced the corresponding manufacturing technology is: a better indication of this is transistor density.
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Universal Flash Storage (UFS) is a flash storage specification for digital cameras, mobile phones and consumer electronic devices. It was designed to bring higher data transfer speed and increased reliability to flash memory storage, while reducing market confusion and removing the need for different adapters for different types of cards. The standard encompasses both packages permanently attached (embedded) within a device (eUFS), and removable UFS memory cards.
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