with the rapid development of photoelectric and micro-electric manufacturing technology, electronic products are always developing in the direction of smaller, lighter and cheaper, so the packaging form of chip components is also constantly improved. There are many kinds of chip packaging technologies, such as DIP, POFP, TSOP, BGA, QFP, CSP, etc. There are more than thirty kinds, and they have experienced the development from DIP, TSOP to BGA. The packaging technology of chips has undergone several generations of changes, with increasingly advanced performance, closer chip area to packaging area, higher application frequency, better temperature resistance, increased pin number, reduced pin spacing, reduced weight, improved reliability and more convenient use.
DIP package
in the 197s of last century, chip packages were basically in the form of DIP(Dual ln-line Package), which was suitable for PCB (printed circuit board) perforation installation and convenient for wiring and operation. DIP package has various structural forms, including multi-layer ceramic DIP, single-layer ceramic DIP, lead frame DIP and so on. However, the packaging efficiency of DIP packaging is very low, and the ratio of chip area to packaging area is 1: 1.86, so the area of the packaged product is larger, and the area of the PCB board of the memory stick is fixed. The larger the packaging area, the less chips are installed in the memory and the smaller the memory stick capacity. At the same time, the larger package area has an impact on the memory frequency, transmission rate and the improvement of electrical performance. Ideally, the ratio of chip area to package area will be 1: 1, but this is impossible unless packaging is not carried out, but with the development of packaging technology, this ratio is getting closer and closer, and now there is a memory packaging technology of 1: 1.14.
TSOP packaging
in the 198s, the second generation of memory packaging technology TSOP appeared, which was widely recognized by the industry and is still the mainstream technology of memory packaging today. TSOP is the abbreviation of "Thin Small Outline Package", which means thin and small package. TSOP memory is made of pins around the chip and directly attached to the surface of PCB by SMT technology. When the TSOP package is in overall size, the parasitic parameters (the output voltage disturbance will be caused when the current changes greatly) are reduced, which is suitable for high-frequency applications, convenient to operate and high in reliability. At the same time, TSOP packaging has the advantages of high yield and low price, so it has been widely used.
in tsop packaging mode, the memory chip is soldered on the PCB through the chip pins, and the contact area between the solder joint and the PCB is small, which makes it relatively difficult for the chip to transfer heat to the PCB. Moreover, when the memory in TSOP packaging mode exceeds 15MHz, it will cause great signal interference and electromagnetic interference.
BGA packaging
In the 199s, with the development of technology, the integration of chips has been continuously improved, the number of I/O pins has increased dramatically, the power consumption has also increased, and the requirements for integrated circuit packaging have become more stringent. In order to meet the needs of development, BGA packaging has been applied to production. BGA is the abbreviation of English Ball Grid Array Package, namely ball grid array package.
The memory encapsulated by BGA technology can increase the memory capacity by two to three times under the condition of constant volume. Compared with TSOP, BGA has smaller volume and better heat dissipation and electrical performance. BGA packaging technology has greatly improved the storage capacity per square inch, and the memory products using BGA packaging technology are only one-third of TSOP packaging under the same capacity. In addition, compared with the traditional TSOP packaging method, BGA packaging method has a faster and more effective way to dissipate heat.
I/O terminals of 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, thus improving the assembly yield. Although its power consumption increases, BGA can be soldered by controlled collapse chip method, which can improve its electrothermal performance. The thickness and weight are reduced compared with the previous packaging technology; The parasitic parameters are reduced, the signal transmission delay is small, and the use frequency is greatly improved; * * * surface welding can be used for assembly, which has high reliability.
when it comes to BGA packaging, we can't help but mention TinyBGA technology patented by Kingmax. TinyBGA is called Tiny Ball Grid Array in English, which belongs to a branch of BGA packaging technology and was successfully developed by Kingmax in August 1998. The ratio of chip area to packaging area is not less than 1:1.14. It can improve the memory capacity by 2 ~ 3 times under the condition of constant volume. Compared with TSOP packaging products, it has smaller volume, better heat dissipation performance and electrical performance.
the size of memory products with TinyBGA packaging technology is only 1/3 of that of TSOP packaging under the same capacity. The pins of TSOP package memory are led out from the periphery of the chip, while TinyBGA is led out 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 that of the traditional TSOP technology, so the signal attenuation is also reduced. This not only greatly improves the anti-interference and anti-noise performance of the chip, but also improves the electrical performance. TinyBGA packaging chip can resist external frequency up to 3MHz, while traditional TSOP packaging technology can only resist external frequency up to 15MHz.
the memory in Tiny BGA package is thinner (the package height is less than .8mm), and the effective heat dissipation path from the metal substrate to the radiator is only .36 mm.. Therefore, TinyBGA memory has higher heat conduction efficiency, which is very suitable for long-term running systems and has excellent stability.
CSP package
CSP(Chip Scale Package) means chip-level package. CSP packaging is the latest generation of memory chip packaging technology, and its technical performance has been improved. CSP package can make the ratio of chip area to package area exceed 1:1.14, which is quite close to the ideal situation of 1:1. The absolute size is only 32 square millimeters, which is about 1/3 of that of ordinary BGA and 1/6 of that of TSOP memory chip. Compared with BGA package, CSP package can increase the storage capacity by three times in the same space.
CSP packaged memory is not only small in size, but also thinner. The most effective heat dissipation path from the metal substrate to the radiator is only .2 mm, which greatly improves the reliability of the memory chip after long-term operation, significantly reduces the line impedance and greatly improves the chip speed.
The center pin form of CSP packaged memory chip effectively shortens the signal transmission distance, reduces its attenuation, and greatly improves the chip's anti-interference and anti-noise performance, which also improves the access time of CSP by 15%-2% compared with BGA. In CSP packaging mode, memory particles are soldered on PCB by solder balls. Because of the large contact area between solder joints and PCB, the heat generated by memory chips during operation can be easily conducted to PCB and radiated. CSP package can dissipate heat from the back with good thermal efficiency. The thermal resistance of CSP is 35℃/W, while that of TSOP is 4℃/w..