Ⅰ Semiconductor package concept explained

Semiconductor package refers to the process of processing the tested wafers according to the product model and functional requirements to obtain independent chips. As a verb, "package" emphasizes the process and actions of placing, fixing, sealing, and leads; as a noun, "package" mainly focuses on the form and category of the package, the material of the substrate and shell, and the lead, emphasizing its protection of the chip, enhancement of electric heating performance and its role in and convenient assembly of the whole machine.

The process of the semiconductor package is: the wafer from the previous wafer process is cut into small dies after the dicing process, and then the cut wafers are mounted on the corresponding islands of the substrate rack with glue. Then use ultra-fine metal (gold, tin, copper, aluminum) wire or conductive resin to connect the bond pad of the chip to the corresponding lead of the substrate to form the required circuit. Then the independent chip is packaged and protected with a plastic casing. After plastic packaging, a series of operations are required. After the packaging is completed, the finished product is tested. Usually, it passes through the procedures of Incoming, Test, and Packing, and finally warehouses and ships.

Ⅱ Semiconductor package classification

Features and advantages of various semiconductor packaging forms:

DIP dual in-line package

DIP (Dual In-line) Package refers to an integrated circuit chip packaged in a dual in-line form. The vast majority of small and medium-sized integrated circuits (ICs) use this type of package, and the number of pins generally does not exceed 100. The CPU chip in the DIP package has two rows of pins, which need to be inserted into the chip socket with the DIP structure. Of course, it can also be directly inserted into a circuit board with the same number of solder holes and geometric arrangement for soldering. The DIP packaged chip should be especially careful when plugging and unplugging from the chip socket to avoid damaging the pins.

DIP package

DIP package has the following characteristics:

1. Suitable for perforation welding on PCB (printed circuit board), easy to operate.

2. The ratio between the chip area and the packaging area is larger, so the volume is also larger.

The 8088 in the Intel series CPU adopts this kind of packaging, and the cache and early memory chips are also this kinds of packaging.

BGA ball grid array package

With the development of integrated circuit technology, the package requirements for integrated circuits have become more stringent. This is because the packaging technology is related to the functionality of the product. When the frequency of the IC exceeds 100MHz, the traditional packaging method may produce the so-called "CrossTalk" phenomenon. And when the number of IC pins is greater than 208 Pin, the traditional packaging method has its difficulties. Therefore, in addition to the QFP packaging method, most of today's high-pin count chips (such as graphics chips and chipsets, etc.) use BGA (Ball Grid Array Package) package technology. As soon as BGA appeared, it became the best choice for high-density, high-performance, multi-pin packages such as CPUs and south/north bridge chips on motherboards.

BGA package

BGA package technology can be divided into five categories in detail:

1. PBGA (Plasric BGA) substrate: generally a multi-layer board composed of 2-4 layers of organic materials. In Intel series CPU, Pentium II, III, IV processors all adopt this kind of packaging form.

2. CBGA (Ceramic BGA) substrate: it is a ceramic substrate. The electrical connection between the chip and the substrate usually adopts the installation method of flip chip (FC for short). In the Intel series CPUs, Pentium I, II, and Pentium Pro processors have all used this type of package.

3. FCBGA (Filp Chip BGA) substrate: hard multilayer substrate.

4. TBGA (Tape BGA) substrate: the substrate is a ribbon-shaped soft 1-2 layer PCB circuit board.

5. CDPBGA (Carity Down PBGA) substrate: refers to the chip area (also called cavity area) with a square depression in the center of the package.

The BGA package has the following characteristics:

1. Although the number of I/O pins has increased, the distance between the pins is much larger than the QFP packaging method, which improves the yield.

2. Although the power consumption of the BGA increases, it can improve the electric heating performance because of the controllable collapse chip method.

3. The signal transmission delay is small, and the adaptation frequency is greatly improved.

4. Coplanar welding can be used for assembly, and the reliability is greatly improved.

The BGA package has entered the practical stage after more than ten years of development. In 1987, Japan's Citizen company began to develop plastic package ball grid array chips (ie BGA). Then, Motorola, Compaq, and other companies immediately joined the ranks of the development of BGA. In 1993, Motorola took the lead in applying BGA to mobile phones. In the same year, Compaq also applied it on workstations and PC computers. Until five or six years ago, Intel began to use BGA in computer CPUs (ie Pentium II, Pentium III, Pentium IV, etc.) and chipsets (such as i850), which contributed to the expansion of BGA applications. BGA has become an extremely popular IC package technology.

QFP plastic square flat package and PFP plastic flat package

The QFP (Plastic Quad Flat) package has a small distance between the pins of the chip, and the pins are very thin. Generally, large-scale or very large integrated circuits use this type of package, and the number of pins is generally more than 100. Chips packaged in this form must be soldered to the motherboard using SMD (Surface Mount Device Technology). Chips mounted by SMD do not need to be punched on the motherboard. Generally, there are designed solder joints with corresponding pins on the surface of the motherboard. Align the pins of the chip with the corresponding solder joints to realize the soldering with the motherboard. Chips soldered in this way are difficult to disassemble without special tools.

QFP package

The chips packaged in the PFP (Plastic Flat Package) are basically the same as the QFP. The only difference is that QFP is generally square, while PFP can be either square or rectangular.

PFP package

QFP/PFP package has the following characteristics:

1. Suitable for SMD surface mounting technology to install wiring on PCB circuit board.

2. Suitable for high-frequency use.

3. Convenient operation and high reliability.

4. The ratio between chip area and package area is small.

The 80286, 80386 and some 486 motherboards in the Intel series CPU adopt this package form.

PGA pin grid array package

The PGA (Pin Grid Array) package has multiple square array pins inside and outside the chip, and each square array pin is arranged at a certain distance along the periphery of the chip. According to the number of pins, 2-5 circles can be formed. When installing, insert the chip into a special PGA socket. In order to make the CPU more convenient to install and remove, starting with the 486 chip, a CPU socket named ZIF appeared, specifically used to meet the requirements of the PGA packaged CPU in the installation and removal.

PGA package

ZIF (Zero Insertion Force Socket) refers to a socket with zero insertion force. Raise the wrench on this socket slightly, and the CPU can be easily inserted into the socket. Then press the wrench back to its original position, and use the squeezing force generated by the special structure of the socket to firmly contact the pins of the CPU with the socket. There is absolutely no problem with poor contact. To remove the CPU chip, you need to lift the wrench of the socket slightly, then the pressure is relieved, and the CPU chip can be easily taken out.

The PGA package has the following characteristics:

1. The plugging operation is more convenient and the reliability is high.

2. It Can adapt to higher frequencies.

In Intel series CPU, 80486 and Pentium, Pentium Pro all adopt this kind of package form.

MCM multi-chip module

In order to solve the problems of low integration and insufficient functions of a single chip, multiple highly integrated, high-performance, and high-reliability chips are used to form a variety of electronic module systems on a high-density multilayer interconnection substrate using SMD technology. Thus appeared MCM (Multi Chip Model) system.

MCM multi-chip module

MCM has the following characteristics:

1. The package delay time is reduced, and it is easy to realize the high-speed module.

2. Reduce the package size and weight of the whole machine/module.

3. The system reliability is greatly improved.

In short, due to the continuous development of CPUs and other very large integrated circuits, the package forms of integrated circuits have also been adjusted and changed accordingly, and the progress of package forms will in turn promote the development of chip technology.

CSP chip size package

With the global demand for personalized and lightweight electronic products, package technology has advanced to CSP (Chip Size Package). It reduces the size of the chip package outline so that the size of the package can be as large as the bare chip size. That is, the size of the packaged IC is no more than 1.2 times the chip, and the IC area is no more than 1.4 times larger than the die.

nvp2441 imx307lqd (CSP package)

CSP package can be divided into four categories:

1. Lead Frame Type, representative manufacturers include Fujitsu, Hitachi, Rohm, Goldstar, and so on.

2. Rigid Interposer Type, representative manufacturers include Motorola, Sony, Toshiba, Panasonic, and so on.

3. Soft Interposer Type, the most famous of which is Tessera's microBGA, CTS's sim-BGA also uses the same principle. Other representative manufacturers include General Electric (GE) and NEC.

4. Wafer Level Package: Different from the traditional single-chip packaging method, WLCSP cuts the entire wafer into a single chip. It is known as the future mainstream of packaging technology and has been put into research and development. The manufacturers include FCT, Aptos, Casio, EPIC, Fujitsu, Mitsubishi Electronics, etc.

The CSP package has the following characteristics:

1. It meets the increasing demand of chip I/O pins.

2. The ratio between chip area and package area is very small.

3. Greatly shorten the delay time.

The CSP package is suitable for ICs with a small number of pins, such as memory sticks and portable electronic products. In the future, it will be widely used in information appliances (IA), digital television (DTV), e-books, wireless network WLAN/GigabitEthemet, ADSL/mobile phone chips, Bluetooth, and other emerging products.