One of the functions of integrated circuit packaging is to protect the chip from external air. Therefore, it is necessary to adopt different processing methods and choose different packaging materials according to the specific requirements and use places of different types of integrated circuits to ensure the airtightness of the packaging structure to meet the specified requirements. The early packaging materials of integrated circuits were mixed with organic resin and wax, and the packaging was realized by filling or pouring, which obviously had poor reliability. Rubber was also used for sealing, but it was eliminated because of its poor heat resistance, oil resistance and electrical performance. At present, the most widely used and reliable airtight sealing materials are glass-metal seal, ceramic-metal package and low melting point glass-ceramic seal. In order to meet the needs of mass production and cost reduction, plastic mold packaging appears in large numbers. The thermosetting resin is heated and pressurized by the mold. Its reliability depends on the characteristics and molding conditions of organic resin and additives. However, due to its poor heat resistance and hygroscopicity, it can not be compared with other sealing materials, and it still belongs to semi-airtight or non-airtight sealing materials. With the maturity of chip technology and the rapid improvement of chip yield, the proportion of back sealing cost to the cost of the whole integrated circuit is also increasing, and the changes and development of packaging technology are changing with each passing day, which is dizzying.
What is the chip package of pcb?
Each chip has a data sheet, and there will be application description, structural package, material number and other descriptions on data sheet T. When making decals for power PCB, you need to refer to the structural package description in the data sheet, including the size, shape and order of each pad.
What's the difference in chip packaging?
Overview of chip packaging methods;
1, BGA (ball grid array)
Spherical contact display, one of surface mount packages. Spherical bumps are made on the back of the printed substrate instead of pins, LSI chips are assembled on the front of the printed substrate, and then sealed with molding resin or potting. Also known as bump display carrier (PAC). There can be more than 200 pins, which is the package of multi-pin LSI. The package can also be made smaller than QFP (quad pin flat package). For example, a 360-lead BGA with a pin center distance of 1.5mm is only 3 1mm square; A 304-pin QFP with a center-to-center distance of 0.5 mm is 40 mm2. And BGA doesn't have to worry about pin deformation like QFP. Developed by Motorola, the software package was first used in portable phones and other devices, and may be popularized in personal computers in the United States in the future. At first, the center distance between the pins (bumps) of BGA was 1.5mm, and the number of pins was 225. Now some LSI manufacturers are developing 500-pin BGA. The problem of BGA is visual inspection after reflow soldering. It is not clear whether this is an effective visual inspection method. Some people think that because of the great distance between welding centers, the connection can be regarded as stable and can only be handled through functional inspection. Motorola Company of the United States calls the package sealed with molding resin OMPAC and the package sealed with potting method GPAC (see OMPAC and GPAC).
2. BQFP (square flat package with buffer)
Four-sided pin flat package with buffer pad. One of QFP packages, bumps (buffer pads) are set at the four corners of the package to prevent the pins from bending and deforming during transportation. American semiconductor manufacturers mainly use this package in microprocessor, ASIC and other circuits. The pin center distance is 0.635 mm, and the number of pins ranges from 84 to 196 (see QFP).
3. Pin grid array (PGA)
Another name for surface mount PGA (see surface mount PGA).
4. Carbon-(ceramics)
A mark representing a ceramic package. For example, CDIP stands for ceramic dipping sauce. This is a symbol that is often used in practice.
5、Cerdip
ECL RAM, DSP (digital signal processor) and other circuits are packaged in glass-sealed ceramic dual in-line package. Cerdip with glass window is used for ultraviolet erasing EPROM and microcomputer circuit with built-in EPROM. The needle center distance is 2.54mm, and the number of needles varies from 8 to 42. In Japan, this package is called DIP-G(G stands for glass seal).
6、Cerquad
A surface mount package, namely ceramic QFP with lower seal, is used to package logic LSI circuits such as DSP. Cerquad with windows is used to package EPROM circuits. The heat dissipation is better than that of plastic QFP, and the power of 1.5~ 2W can be allowed under natural air cooling conditions. But the packaging cost is 3 ~ 5 times higher than that of plastic QFP. Pin center distance 1.27mm, 0.8mm, 0.65mm, 0.5mm, 0.4mm and other specifications. The number of pins ranges from 32 to 368.
7. CLCC (ceramic lead chip carrier)
Ceramic chip carrier with pins is a kind of surface mount package, which is led out from four sides of the package in a T shape.
The window is used to encapsulate the ultraviolet erasable EPROM and the microcomputer circuit with EPROM. This package is also called QFJ and QFJ-g (see QFJ).
8. COB (chip on board)
Chip on board packaging is one of the bare chip mounting technologies. The semiconductor chip is attached to the printed circuit board, and the electrical connection between the chip and the substrate is realized by wire stitching, and the electrical connection between the chip and the substrate is realized by wire stitching and covered with resin to ensure reliability. Although COB is the simplest die mounting technology, its packaging density is far less than TAB and flip-chip bonding technology.
9. DFP (Double Flat Package)
Double-sided pin flat package. This is s >>
What is the principle of chip packaging?
Using vinyl packaging means COB (chip on board) packaging.
COB packaging process is as follows:
Step 1: Crystal expansion. The whole LED wafer film provided by the manufacturer is evenly expanded by the expander, and the tightly arranged LED grains attached to the film surface are pulled away, which is convenient for die bonding.
Step 2: Glue the back. Put the crystal expanding ring of crystal expanding on the rubber back machine surface scraped by the silver paste layer and back it with silver paste. Point the silver paste. Suitable for bulk LED chips. A proper amount of silver paste is dispensed on the PCB printed circuit board by using a dispensing machine.
Step 3: put the crystal expanding ring inlaid with silver paste into the crystal thorn frame, and the operator pricks the LED chip on the PCB printed circuit board with the crystal thorn pen under the microscope.
Step 4: Put the PCB printed circuit board with the crystal in the thermal cycle oven and let it stand at a constant temperature for a period of time, and take it out after the silver paste solidifies (don't leave it for a long time, otherwise the LED chip coating will be baked yellow, that is, oxidized, which will lead to bonding difficulties). If there is LED chip bonding, the above steps are required; If only the IC chip is bonded, the above steps are cancelled.
Step 5: Bonding the chip. Put a proper amount of red glue (or black glue) on the ic position of PCB printed circuit board with a glue dispenser, and then put the IC bare chip on the red glue or black glue correctly with anti-static equipment (vacuum suction pen or children).
Step 6: drying. Put the bonded die in a thermal cycle oven and put it on a large flat heating plate and let it stand at a constant temperature for a period of time, or it can be cured naturally (for a long time).
Step 7: Bonding (stringing). Aluminum wire bonder is used to bridge the wafer (LED die or IC chip) with the corresponding bonding pad aluminum wire on PCB, that is, to weld the inner lead of COB.
Step 8: Pre-test. Use special testing tools (COB has different equipment according to different uses, in short, high-precision regulated power supply) to test COB boards, and rework unqualified boards.
Step 9: dispense glue. Using a dispensing machine, the prepared AB glue is properly placed on the bonded LED die, and the IC is encapsulated with black glue, and then the appearance packaging is carried out according to the customer's requirements.
Step 10: curing. Put the sealed PCB into a thermal cycle oven and let it stand at a constant temperature. Different drying time can be set as required.
Step 11: Post-test. Use special testing tools to test the electrical performance of the packaged PCB printed circuit board to distinguish the good from the bad.
Step 12: Polishing. Polishing according to customer's requirements for product thickness (generally soft PCB).
Step 13: Clean. Cleaning products.
Step 14: air drying. The product after the second air drying and cleaning.
Step 15: Test. Success depends on this step (there is no better way to remedy bad movies).
Step 16: Cut. Cut the large PCB to the size required by customers.
Step 17: Pack and leave the factory. Packaging products.
The melting point of vinyl is relatively low. When assembling, the wires and the like are encapsulated with vinyl first, and then the fragile components such as chips are assembled. After adding vinyl once, the packaging will not damage the components because there is less vinyl added later.
Introduction of chip packaging
The shell on which the semiconductor integrated circuit chip is installed plays the role of placing, fixing, sealing, protecting the chip and enhancing the electrothermal performance, and it is also a bridge to communicate the internal world of the chip with external circuits-the contacts on the chip are connected to the pins of the package shell through wires, and these pins are connected to other devices through wires on the printed board. Therefore, packaging plays an important role in CPU and other LSI integrated circuits.
What material is used for chip packaging?
The most important things are epoxy resin and ceramics.
What is the difference between chip package DIP and SOP?
The former is dual in-line package, and the latter is the most common patch package. As shown in the following figure (DIP is marked as N, SOP as D)-
Semiconductor package, what does semiconductor package mean?
Introduction to semiconductor packaging:
The semiconductor production process includes wafer manufacturing, wafer testing, chip packaging and post-packaging testing. Semiconductor packaging refers to the process of processing the wafer that has passed the test into independent chips according to the product model and functional requirements. The packaging process is as follows: the wafer from the previous wafer cutting process is cut into small dies, then the cut dies are attached to the islands of the corresponding substrate (lead frame) with glue, and then the pads of the dies are connected to the corresponding leads of the substrate by using ultra-fine metal (gold, tin, copper, aluminum) wires or conductive resin to form the required pads. Then, the individual wafers are encapsulated and protected with a plastic case. After plastic sealing, a series of operations are carried out, such as post-mold curing, rib cutting and edge cutting; ), electroplating and printing. After the packaging is completed, the finished product is inspected, usually through the processes of incoming inspection, inspection and packaging, and finally put into storage for shipment. Typical packaging processes are: dicing, bonding, plastic packaging, deburring, electroplating, printing, rib cutting, molding appearance inspection, finished product inspection, packaging and shipment.
1 Overview of semiconductor device packaging
Electronic products consist of semiconductor devices (integrated circuits and discrete devices), printed circuit boards, wires, an integral frame, a shell and a display, wherein the integrated circuit is used for processing and controlling signals, the discrete devices are usually used for amplifying signals, the printed circuit boards and wires are used for connecting signals, the integral frame shell plays a supporting and protecting role, and the display part serves as an interface for communicating with people. Therefore, semiconductor devices are the main and important components of electronic products, and have the reputation of "the rice of industry" in the electronic industry.
China developed and produced the first computer in 1960s, covering an area of about 100 m2. Today's portable computers are only the size of schoolbags, and future computers may be as big as pens or smaller. The rapid shrinking of computer size and increasingly powerful functions are a good proof of the development of semiconductor technology. Its contribution is mainly attributed to: (1) the great improvement of semiconductor chip integration and the improvement of lithography accuracy in wafer manufacturing, which makes the chip more powerful and smaller in size; (2) With the improvement of semiconductor packaging technology, the density of integrated circuits on printed circuit boards is greatly increased, and the volume of electronic products is greatly reduced.
The progress of semiconductor assembly technology is mainly reflected in the continuous development of its packaging. Generally speaking, assembly can be defined as a process technology that uses membrane technology and micro-connection technology to connect a semiconductor chip with a conductor part in a lead frame, a substrate, a plastic film or a printed circuit board to lead out lead pins, and then potting and fixing the lead pins through a plastic insulating medium to form a whole three-dimensional structure. It has the functions of circuit connection, physical support protection, field shielding, stress buffering, heat dissipation, oversize and standardization. From plug-in package in triode era, surface mount package in 1980s to module package and system package now, many packaging forms have been developed by predecessors, and each new packaging form may require new materials, new processes or new equipment.
The driving force for the continuous development of semiconductor packaging forms is its price and performance. The final customers of the electronic market can be divided into three categories: home users, industrial users and national users. The biggest feature of home users is low price and low performance requirements; National users require high performance, and the price is usually dozens or even thousands of times that of ordinary users, which is mainly used in military and aerospace fields; Industrial users are usually between the above two in terms of price and performance. Low price requires reducing the cost on the original basis, so that the less materials, the better, and the greater the one-time output, the better. High performance requires long product life and can withstand harsh environments such as high temperature, low temperature and high humidity. Semiconductor manufacturers are always trying to reduce costs and improve performance. Of course, there are other factors, such as environmental requirements and patent issues, which force them to change the packaging type.
2 The role of packaging
Packaging is necessary and crucial for the chip. Packaging can also refer to the installation of semiconductor integration ... >; & gt
What kind of package does this chip belong to?
Bundles, commonly known as cow dung, are the cheapest and easy to get wet and lead to failure.
What are the common chip packages?
dual inline pin package
DIP (dual in-line package) refers to an integrated circuit chip packaged in dual in-line form. Most small and medium-sized integrated circuits (IC) adopt this packaging form, and the number of pins generally does not exceed 100. The CPU chip in DIP package has two rows of pins, which need to be inserted into the chip socket in DIP structure. Of course, it can also be directly inserted into the same number and geometric arrangement of welding holes on the circuit board for welding. DIP packaged chips should be carefully plugged and unplugged from the chip socket to avoid damaging the pins.
DIP package has the following characteristics:
1. It is suitable for punching and welding on PCB (printed circuit board) and easy to operate.
2. The ratio of chip area to package area is large, so the volume is also large.
The 8088 in Intel series CPU adopts this packaging form, as do the cache and early memory chips.
Second, QFP plastic square flat package and PFP plastic flat component package
QFP (plastic quad flat package) package has small pin spacing and thin pins, and is generally used for large-scale or ultra-large-scale integrated circuits, and the number of pins is generally above 100. Chips packaged in this way must be soldered to the motherboard by SMD (Surface Mount Device Technology). Chip mounted by SMD does not need to be punched on the motherboard, and there are usually designed solder joints corresponding to pins on the surface of the motherboard. By aligning each pin of the chip with the corresponding solder joint, the bonding with the motherboard can be realized. Chips soldered in this way are difficult to disassemble without special tools.
The chip packaged by PFP is basically the same as the chip packaged by QFP. The only difference is that QFP is generally square, while PFP can be square or rectangular.
PFP 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 very small.
The 80286, 80386 and some 486 motherboards in Intel series CPU adopt this packaging form.
Thirdly, PGA pin grid array package
The packaging form of PGA(Pin Grid Array Package) chip has a plurality of square pins inside and outside the chip, and each square pin is arranged at a certain distance around the chip. According to the number of stitches, 2-5 loops can be formed. When installing, insert the chip into the dedicated PGA socket. In order to make the installation and disassembly of CPU more convenient, a CPU socket named ZIF appeared from 486 chip, which was specially used to meet the installation and disassembly requirements of CPU in PGA package.
ZIF (zero insertion force socket) refers to a socket with zero insertion force. Gently lift the wrench on this socket, and the CPU can be easily inserted into the socket. Then the wrench is pressed back to its original position, and the pin of the CPU is firmly contacted with the socket by using the extrusion force generated by the special structure of the socket itself, and there is absolutely no problem of poor contact. To take out the CPU chip, just gently lift the socket wrench, the pressure will be released, and the CPU chip can be easily taken out.
The PGA package has the following characteristics:
1. The plug-in is more convenient and reliable to operate.
2. It can adapt to higher frequencies.
In Intel series CPU, 80486, Pentium and Pentium Pro all adopt this packaging form.
Fourth, BGA ball grid array package.
With the development of integrated circuit technology, the packaging requirements of integrated circuits are more stringent. This is because the packaging technology is related to the function of the product. When the frequency of the integrated circuit exceeds 100MHz, the so-called "crosstalk" may appear in the traditional packaging method, and when the number of pins of the integrated circuit exceeds 208, the traditional packaging method has its difficulties. Therefore, in addition to QFP packaging, most high pin count chips (such as graphics chips and chipsets) now adopt BGA (ball grid array package) packaging technology. As soon as BGA appeared, it became high-density, high-performance, and multi-reference, such as CPU and North/South Bridge chip on the motherboard ... > >