There are three differences between PLCC packaging and PQFP packaging:
1. The number of pins in the two packages is different: the number of pins in the PLCC package is 32; while the number of pins in the PQFP package is The number is generally above 100.
2. The packaging objects of the two are different: Generally, large-scale or very large-scale integrated circuits adopt PQFP packaging. PQFP packaging is suitable for SMT surface mounting technology and wiring on PCB, and is suitable for high-frequency use; plcc packaging It is a special pin chip package, also a plastic chip carrier with leads, one of the surface mount packages.
3. The two have different advantages: PLCC packaging has the advantages of small size and high reliability. The welding of this chip uses a reflow soldering process, which requires special welding equipment and must be removed during debugging. Chips are also very troublesome and are rarely used now; PQFP packaging has the advantages of easy operation, mature technology, and low price.
Extended information:
PQFP packaged chips have pins all around, and the distance between the pins is very small, and the pins are also very thin. Generally, large-scale or ultra-large-scale integration The circuit adopts this packaging form. Chips packaged in this form must use SMT technology. Solder the pins on the side of the chip to the motherboard.
Chips installed using SMT do not need to be drilled on the motherboard. Generally, there are designed solder joints for corresponding pins on the surface of the motherboard. Align each pin of the chip with the corresponding solder point to achieve soldering to the motherboard.
Due to the limited side length of the chip, the number of pins in the PQFP package cannot be increased, thus limiting the development of graphics acceleration chips. Parallel pins are also a stumbling block that hinders the continued development of PQFP packaging, because parallel pins will generate a certain capacitance when transmitting high-frequency signals, thereby generating high-frequency noise signals.
In addition, long pins can easily absorb this kind of interference noise, just like the antenna of a radio. Hundreds of "antennas" interfere with each other, making it difficult for PQFP packaged chips to work in larger environments. at high frequencies. In addition, the chip area/package area ratio of PQFP packaging is too small, which also limits the development of PQFP packaging. In the late 1990s, as BGA technology continued to mature, PQFP was finally eliminated by the market.
Baidu Encyclopedia-PLCC packaging
Baidu Encyclopedia-PQFP packaging