Package on a package (PoP) is an

integrated circuit packaging In electronics manufacturing, integrated circuit packaging is the final stage of semiconductor device fabrication, in which the block of semiconductor material is encapsulated in a supporting case that prevents physical damage and corrosion. ...

method to vertically combine discrete logic and memory

ball grid array A ball grid array (BGA) is a type of surface-mount packaging (a chip carrier) used for integrated circuits. BGA packages are used to permanently mount devices such as microprocessors. A BGA can provide more interconnection pins than can be put ...

(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 phone A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive telephone call, calls over a radio freq ...

personal digital assistant A personal digital assistant (PDA), also known as a handheld PC, is a variety mobile device which functions as a personal information manager. PDAs have been mostly displaced by the widespread adoption of highly capable smartphones, in part ...

s (PDA), and

digital camera A digital camera is a camera that captures photographs in digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film. Digital cameras are now widely incorporated into mobile devic ...

s, at the cost of slightly higher height requirements. Stacks with more than 2 packages are uncommon, due to heat dissipation considerations.

Configuration

Two widely used configurations exist for PoP: * Pure memory stacking: two or more memory only packages are stacked on each other * Mixed logic-memory stacking: logic (CPU) package on the bottom, memory package on top. For example, the bottom could be a

system on a chip A system on a chip or system-on-chip (SoC ; pl. ''SoCs'' ) is an integrated circuit that integrates most or all components of a computer or other electronic system. These components almost always include a central processing unit (CPU), memor ...

(SoC) for a

. The logic package is on the bottom because it needs many more BGA connections to the motherboard. 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.

Benefits

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 Advanced Semiconductor Engineering, Inc. (), also known as ASE Group (), is a provider of independent semiconductor assembling and test manufacturing services, with its headquarters in Kaohsiung, Taiwan. Overview The company was founded in 1984 ...

(ASE).

Advantages over traditional isolated-chip packaging

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.

Advantages over chip stacking

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: * The memory package can be tested separately from the logic package * Only "known good" packages are used in final assembly (if the memory is bad only the memory is discarded and so on). Compare this to stacked-die packages where the entire set is useless and rejected if either the memory or logic is bad. * The end user (such as makers of

s or

s) controls the logistics. This means memory from different suppliers can be used at different times without changing the logic. The memory becomes a commodity to be sourced from the lowest cost supplier. This trait is also a benefit compared to PiP (package in package) which requires a specific memory device to be designed in and sourced upstream of the end user. * Any mechanically mating top package can be used. For a low-end phone, a smaller memory configuration may be used on the top package. For a high-end phone, more memory could be used with the same bottom package. This simplifies inventory control by the OEM. For a stacked-die package or even PiP (package in package), the exact memory configuration must be known weeks or months in advance. * Because the memory only comes into the mix at final assembly, there is no reason for logic suppliers to source any memory. With a stacked-die device, the logic provider must buy wafers of memory from a memory supplier.

JEDEC standardization

* JEDEC JC-11 committee deals with package outline drawing standards related to the bottom PoP package. See documents MO-266A and JEDEC publication 95, Design Guide 4.22. * JEDEC JC-63 committee deals with top (memory) PoP package pinout standardization. See JEDEC Standard No. 21-C, Page 3.12.2 – 1

Other names

Package on a package is also known by other names: * PoP: refers to the combined top and bottom packages * PoPt: refers to the top package * PoPb: refers to the bottom package * PSvfBGA: refers to the bottom package: ''P''ackage ''S''tackable ''V''ery thin ''F''ine pitch ''B''all ''G''rid ''A''rray * PSfcCSP: refers to the bottom package: ''P''ackage ''S''tackable ''F''lip ''C''hip ''C''hip ''S''cale ''P''ackage

History

In 2001, a

Toshiba , commonly known as Toshiba and stylized as TOSHIBA, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. Its diversified products and services include power, industrial and social infrastructure systems ...

research team including T. Imoto, M. Matsui and C. Takubo developed a "System Block Module" wafer bonding process for manufacturing

3D integrated circuit A three-dimensional integrated circuit (3D IC) is a MOSFET, MOS (metal-oxide semiconductor) integrated circuit (IC) manufactured by stacking as many as 16 or more ICs and interconnecting them vertically using, for instance, through-silicon vias (TS ...

(3D IC) packages. The earliest known commercial use of a 3D package-on-package chip was in

Sony , commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professional ...

PlayStation Portable The PlayStation Portable (PSP) is a handheld game console developed and marketed by Sony Computer Entertainment. It was first released in Japan on December 12, 2004, in North America on March 24, 2005, and in PAL regions on September 1, 200 ...

(PSP)

handheld game console A handheld game console, or simply handheld console, is a small, portable self-contained video game console with a built-in screen, game controls and speakers. Handheld game consoles are smaller than home video game consoles and contain the cons ...

, released in 2004. The PSP hardware includes eDRAM (embedded

DRAM Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access semiconductor memory that stores each bit of data in a memory cell, usually consisting of a tiny capacitor and a transistor, both typically based on metal-oxi ...

) memory manufactured by

in a 3D package chip with two dies stacked vertically. Toshiba called it "semi-embedded DRAM" at the time, before later calling it a stacked "chip-on-chip" (CoC) solution. In April 2007, Toshiba commercialized an eight-layer 3D chip package, the 16 GB THGAM embedded

NAND flash Flash memory is an electronic non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for the NOR and NAND logic gates. Both us ...

memory chip, which was manufactured with eight stacked 2GB NAND flash chips. The same month, ("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 Maxim Integrated, a subsidiary of Analog Devices, designs, manufactures, and sells analog and mixed-signal integrated circuits for the automotive, industrial, communications, consumer, and computing markets. Maxim's product portfolio includes ...

. In September 2007, Hynix Semiconductor introduced 24-layer 3D packaging technology, with a 16GB flash memory chip that was manufactured with 24 stacked NAND flash chips using a wafer bonding process.