Component packaging plays a role in mounting, fixing, sealing, protecting chips and enhancing electrical and thermal performance. At the same time, the contacts on the chip are connected to the pins of the package shell with wires, and these pins are connected with other devices through the wires on the printed circuit board, so as to realize the connection between the internal chip and the external circuit. Therefore, the chip must be isolated from the outside world to prevent the corrosion of the chip circuit caused by the impurities in the air and cause the electrical performance to decline. And the packaged chip is also easier to install and transport. Since the quality of the package directly affects the performance of the chip itself and the design and manufacture of the PCB connected to it, the packaging technology is very important.
An important indicator to measure whether a chip packaging technology is advanced or not is the ratio of chip area to package area. The closer this ratio is to 1, the better.
The main factors to be considered in packaging: the ratio of chip area to package area should be as close as possible to 1:1 in order to improve packaging efficiency. The pins should be as short as possible to reduce the delay, and the distance between the pins should be as far as possible to ensure that they do not interfere with each other and improve performance. Based on heat dissipation requirements, the thinner the package, the better.
Encapsulation has roughly gone through the following development process: structural aspects. TO→DIP→PLCC→QFP→BGA→CSP. material. Metal, ceramic → ceramic, plastic → plastic. pin shape. Long lead in-line → short lead or no lead placement → ball bump. Assembly method. Through-hole insertion → surface mount → direct mount.
The following are the specific packaging forms:
1. SOP/SOIC package
SOP is the abbreviation of English Small Outline Package, that is, small outline package. SOP packaging technology was successfully developed by Philips from 1968 to 1969, and then gradually derived: SOJ, J-pin small outline package; TSOP, thin small outline package; VSOP, very small outline package; SSOP, reduced SOP; TSSOP, Thin Shrink SOP; SOT, Small Outline Transistor; SOIC, Small Outline Integrated Circuit.
2. DIP package
DIP is the abbreviation of "Double In-line Package" in English, that is, 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, and microcomputer circuits.
3. PLCC package
PLCC is the abbreviation of "Plastic Leaded Chip Carrier" in English, that is, plastic package J lead chip package. PLCC package, the shape is square, 32-pin package, there are pins around, the size is much smaller than the DIP package. The PLCC package is suitable for mounting wiring on the PCB with SMT surface mounting technology, and has the advantages of small size and high reliability.
4. TQFP package
TQFP is the abbreviation of "Thin Quad Flat Package" in English, that is, thin plastic four-corner flat package. The quad flat pack process utilizes space efficiently, thereby reducing the space requirement on the printed circuit board. Due to the reduced height and volume, this packaging process is ideal for space-critical applications such as PCMCIA cards and networking devices. Almost all of ALTERA's CPLD/FPGA have TQFP package.
5. PQFP package
PQFP is the abbreviation of "Plastic Quad Flat Package" in English, that is, plastic four-corner flat package. The distance between the chip pins of the PQFP package is very small, and the pins are very thin. Generally large-scale or ultra-large-scale integrated circuits use this package form, and the number of pins is generally more than 100.
6. TSOP package
TSOP is the abbreviation of "Thin Small Outline Package" in English, that is, thin small size package. A typical feature of TSOP memory packaging technology is to make pins around the packaged chip. TSOP is suitable for mounting wiring on PCB with SMT (Surface Mount) technology. TSOP package shape, parasitic parameters (when the current changes greatly, the output voltage disturbance is reduced), it is suitable for high frequency applications, the operation is more convenient, and the reliability is also relatively high.
7. BGA package
The memory packaged with BGA technology can increase the memory capacity by two to three times without changing the memory volume. Compared with TSOP, BGA has a smaller volume, better heat dissipation and electrical performance. BGA packaging technology has greatly improved the storage capacity per square inch. Under the same capacity, the volume of memory products using BGA packaging technology is only one-third of that of TSOP packaging. In addition, compared with the traditional TSOP packaging method, the BGA packaging method has a faster and more effective way of heat dissipation.
The I/O terminals of the BGA package are distributed under the package in the form of circular or columnar solder joints in an array. The advantage of BGA technology is that although the number of I/O pins has increased, the pin spacing has not decreased but increased. Improved assembly yield. Although its power consumption increases, the BGA can be soldered with a controlled collapse die method, which can improve its electrothermal performance. Compared with the previous packaging technology, the thickness and weight are reduced; the parasitic parameters are reduced, the signal transmission delay is small, and the frequency of use is greatly improved; the assembly can be coplanar welding, and the reliability is high.
8. TinyBGA package
When it comes to BGA packages, we cannot fail to mention Kingmax's patented TinyBGA technology. TinyBGA English full name is "Tiny Ball Grid", which belongs to a branch of BGA packaging technology and was successfully developed by Kingmax Company in August 1998. The ratio of the chip area to the package area is not less than 1:1.14, which can increase the memory capacity by 2 to 3 times when the memory volume remains unchanged. Compared with TSOP package products, it has smaller volume, better heat dissipation performance and electrical performance.
Memory products using TinyBGA packaging technology are only 1/3 the size of TSOP packaging under the same capacity. The pins of the TSOP package memory are drawn from the periphery of the chip, while the TinyBGA is drawn from the center of the chip. This method effectively shortens the transmission distance of the signal, and the length of the signal transmission line is only 1/4 of the traditional TSOP technology, so the attenuation of the signal is also reduced. This not only greatly improves the anti-interference and anti-noise performance of the chip, but also improves the electrical performance. The chip using TinyBGA package can resist FSB up to 300MHz, while the traditional TSOP packaging technology can only resist FSB up to 150MHz.
The thickness of TinyBGA packaged memory is also thinner (package height is less than 0.8mm), and the effective heat dissipation path from the metal substrate to the heat sink is only 0.36mm. Therefore, TinyBGA memory has higher thermal conduction efficiency and is very suitable for long-running systems with excellent stability.
9. QFP package
QFP is the abbreviation of "Quad Flat Package", which is a small square flat package. QFP packages are frequently used in early graphics cards, but there are few QFP packages with a speed of more than 4ns. Due to process and performance issues, they have been gradually replaced by TSOP-II and BGA. The QFP package has pins all around the particle, which are fairly obvious to identify. Four side lead flat pack. One of the surface mount packages, with pins leading out from four sides in a gull-wing (L) shape.
There are three kinds of 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 mostly plastic QFP. Plastic QFP is the most popular multi-pin LSI package. It is not only used in digital logic LSI circuits such as microprocessors and gate arrays, but also in analog LSI circuits such as VTR signal processing and audio signal processing. There are 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.
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