What is integrated circuit packaging:
The packaging form of the integrated circuit is a housing for mounting semiconductor integrated circuit chips. It not only plays the role of mounting, fixing, sealing, protecting the chip and enhancing the electrical and thermal performance, but also connects to the pins of the package shell through the contacts on the chip with wires, and these pins pass through the printed circuit board. The wires are connected with other devices to realize the connection between the internal chip and the external circuit. The quality of packaging technology directly affects the performance of the chip itself and the design and manufacturing of the printed circuit board (PCB) connected to it. Therefore, the form of packaging is very important.
There are many types of integrated circuits (analog circuits, digital circuits, radio frequency circuits, sensors, etc.), so the needs and requirements for packaging are also different, and the types of packaging are also diverse.
The development of integrated circuit packaging:
Integrated circuit packaging is advancing with the development of integrated circuits. With the continuous development of aerospace, aviation, machinery, light industry, chemical industry and other industries, the whole machine is also changing in the direction of multi-function and miniaturization. In this way, the integration level of integrated circuits is required to be higher and higher, and the functions are becoming more and more complex. Correspondingly, the packaging density of integrated circuits is required to increase, the number of leads is increasing, and the volume is getting smaller and lighter, and the replacement is faster and faster. The rationality and scientificity of the packaging structure will directly affect The quality of integrated circuits. Therefore, for manufacturers and users of integrated circuits, in addition to mastering the performance parameters of various integrated circuits and identifying lead arrangements, they must also have knowledge of the overall dimensions, tolerances, structural features, and packaging materials of various integrated circuits. A systematic knowledge and understanding. In order to prevent integrated circuit manufacturers from degrading the performance of integrated circuits due to improper selection of packaging; also to enable integrated circuit users to use integrated circuits for solicitation, design and assembly, and rationalize the layout and space occupation, so as to ensure that the selection is appropriate and the application is reasonable.
Common types of integrated circuit packages:
With the development of the industry and technology, many different types of integrated circuit packaging have appeared. The following is an introduction to some common integrated circuit packaging types:
1. BGA (ball grid array)
A display of spherical contacts, one of the surface mount packages. On the back of the printed circuit board, spherical bumps are produced in the display method to replace the pins, and the LSI chip is assembled on the front side of the printed circuit board, and then sealed by molding resin or potting. Also known as bump display carrier (PAC). Pins can exceed 200, which is a package for multi-pin LSI. The package body can also be made smaller than QFP (Quad Flat Package). For example, a 360-pin BGA with a pin center distance of 1.5mm is only 31mm square; while a 304-pin QFP with a pin center distance of 0.5mm is 40mm square. And BGA does not have to worry about pin deformation like QFP. This package was developed by Motorola Corporation of the United States. It was first adopted in portable phones and other devices, and it may be popularized in personal computers in the United States in the future. Initially, the BGA pin (bump) center distance was 1.5mm, and the number of pins was 225. There are also some LSI manufacturers that are developing 500-pin BGAs. The problem with BGA is the visual inspection after reflow soldering. It is not yet clear whether an effective visual inspection method is available. Some believe that due to the large welding center distance, the connection can be regarded as stable and can only be processed through functional inspection. American Motorola Company calls the package sealed with molded resin OMPAC, and the package sealed with potting method is called GPAC (see OMPAC and GPAC).
2. DIP (dual in-line package)
Dual in-line package. One of the plug-in packages, the pins are drawn from both sides of the package, and the package materials are plastic and ceramic. DIP is the most popular plug-in package, and its applications include standard logic ICs, memory LSIs, microcomputer circuits, etc. The pin center distance is 2.54mm, and the number of pins is from 6 to 64. The package width is usually 15.2mm. Some packages with a width of 7.52mm and 10.16mm are called skinny DIP and slim DIP (narrow DIP) respectively. But in most cases, no distinction is made, and they are simply collectively referred to as DIP.
3. BQFP (quad flat package with bumper)
Four-side pin flat package with cushion. One of the QFP packages, bumps (buffer pads) are provided at the four corners of the package body to prevent the pins from bending and deforming during transportation. American semiconductor manufacturers mainly use this package in circuits such as microprocessors and ASICs. The pin center distance is 0.635mm, and the number of pins ranges from 84 to 196.
4. CLCC (ceramic leaded chip carrier)
Ceramic chip carrier with pins, one of the surface mount packages, the pins are led out from the four sides of the package in a T-shape. It is used to encapsulate the ultraviolet erasable EPROM and the microcomputer circuit with EPROM with windows. This package is also called QFJ, QFJ-G.
5. PGA (pin grid array surface mount type)
Surface mount PGA. Usually called PGA is a plug-in package with a pin length of about 3.4mm. The surface mount PGA has display-like pins on the bottom surface of the package, and the length ranges from 1.5mm to 2.0mm. Mounting uses the method of butt welding with the printed circuit board, so it is also called butt welding PGA. Because the pin center distance is only 1.27mm, which is half smaller than the plug-in type PGA, the package body can be made not so large, and the number of pins is more than that of the plug-in type (250～528), which is a package for large-scale logic LSI . The packaging substrates include multilayer ceramic substrates and glass epoxy resin printing bases. The production of packages with multilayer ceramic substrates has been put into practical use.
6. PGA (pin grid array)
Display pin package. One of the plug-in packages, the vertical pins on the bottom surface are arranged in an array. The packaging substrates are basically multilayer ceramic substrates. In the case that the material name is not specifically indicated, most of them are ceramic PGA, which is used in high-speed large-scale logic LSI circuits. higher cost. The pin center distance is usually 2.54mm, and the number of pins ranges from 64 to 447. In order to reduce costs, the packaging substrate can be replaced by a glass epoxy printed substrate. There are also plastic PGAs with 64 to 256 pins. In addition, there is a short-pin surface-mount PGA (butt-welded PGA) with a pin center distance of 1.27mm.
7. QFP (quad flat package)
Four-side lead flat package. One of the surface mount packages, the pins are led out from four sides in a seagull wing (L) shape. There are three substrates: ceramic, metal and plastic. In terms of quantity, plastic packaging accounts for the vast majority. When the material is not specifically indicated, it is plastic QFP in most cases. Plastic QFP is the most popular multi-pin LSI package. Not only used in digital logic LSI circuits such as microprocessors and gate displays, but also in analog LSI circuits such as VTR signal processing and audio signal processing. The pin center distance has various specifications such as 1.0mm, 0.8mm, 0.65mm, 0.5mm, 0.4mm, 0.3mm and so on. The maximum number of pins in the 0.65mm center distance specification is 304. Japan calls QFPs with a lead center distance less than 0.65mm as QFP (FP). But now the Japanese Electronic Machinery Industry will re-evaluate the form factor of QFP. There is no difference in the center distance of the pins, but according to the thickness of the package body, it is divided into three types: QFP (2.0mm～3.6mm thick), LQFP (1.4mm thick) and TQFP (1.0mm thick).
In addition, some LSI manufacturers refer to QFPs with a pin center distance of 0.5mm as shrink QFPs or SQFPs or VQFPs. However, some manufacturers refer to QFPs with a pin center distance of 0.65mm and 0.4mm as SQFP, which makes the name somewhat confusing. The disadvantage of QFP is that when the pin center distance is less than 0.65mm, the pins are easy to bend. In order to prevent pin deformation, several improved QFP varieties have appeared. For example, BQFP (see BQFP) with tree finger cushions on the four corners of the package; GQFP with resin protection ring covering the front end of the pin (see GQFP); test bumps are set in the package body to prevent pin deformation TPQFP (see TPQFP) that can be tested in a dedicated fixture. In terms of logic LSI, many developed products and high-reliability products are encapsulated in multilayer ceramic QFP. Products with a minimum pin center distance of 0.4mm and a maximum of 348 pins have also been introduced. In addition, there is also a glass-sealed ceramic QFP.
8. LQFP (low profile quad flat package)
Thin QFP. Refers to the QFP with a package body thickness of 1.4mm, which is the name used by the Japanese Electronic Machinery Industry according to the new QFP form factor formulated.
9. PLCC (plastic leaded chip carrier)
Plastic chip carrier with leads. One of surface mount packages. The pins are led out from the four sides of the package in a T-shape and are made of plastic. Texas Instruments in the United States first adopted 64k-bit DRAM and 256kDRAM, and now it has been widely used in logic LSI, DLD (or process logic device) and other circuits. The pin center distance is 1.27mm, and the number of pins ranges from 18 to 84. J-shaped pins are not easy to deform and easier to operate than QFP, but the visual inspection after soldering is more difficult. PLCC is similar to LCC (also called QFN). In the past, the only difference between the two was that the former used plastics and the latter used ceramics. However, J-lead packages made of ceramics and leadless packages made of plastics (marked as plastic LCC, PC LP, P-LCC, etc.) have already appeared, and they are no longer distinguishable. For this reason, the Japanese Electronic Machinery Industry Association decided in 1988 to call a package with J-shaped pins drawn from four sides as QFJ, and a package with electrode bumps on four sides as QFN.
10. QFN (quad flat non-leaded package)
Four-side leadless flat package. One of surface mount packages. It is now called LCC. QFN is the name prescribed by the Japan Electronic Machinery Industry Association. The four sides of the package are equipped with electrode contacts. Because there are no leads, the mounting area is smaller than QFP and the height is lower than QFP. However, when stress is generated between the printed circuit board and the package, it cannot be relieved at the electrode contact. Therefore, it is difficult to make electrode contacts as many QFP pins, generally from 14 to 100. There are two kinds of materials: ceramic and plastic. When there is an LCC mark, it is basically ceramic QFN. The electrode contact center distance is 1.27mm.
11. SOP (Small Out-Line Package)
SOP is based on microwave monolithic integration (MMIc), multi-chip module (McM), digital and analog integration, and optical integration technology. It combines microwave and radio frequency front-end, digital and analog signal processing circuits, memory, and optical devices. A secondary integration technology in which modules are integrated in a package, which is a true system-in-package. Its structure is shown in Figure 1. It is easy to realize the miniaturization, light weight, high performance and high reliability of the electronic system. It is especially suitable for aviation, aerospace, portable electronic systems and other occasions that have strict requirements on volume, weight and environment.
Other names for SOP include: SO (small out-line), SOIC (small out-line integrated circuit)
