Detailed introduction to the PCB design of the 9 common components package

Component packaging plays a role in installing, fixing, sealing, protecting the chip and enhancing the electrical and thermal properties. At the same time, through the contacts on the chip with wires connected to the pins of the package shell, these pins are connected to other devices through the wires on the printed circuit board, so as to achieve the connection between the internal chip and the external circuit. Therefore, the chip must be isolated from the outside world to prevent airborne impurities on the chip circuit corrosion caused by electrical performance degradation. And the encapsulated chip is also easier to install and transport. As the package is good or bad, directly affecting the performance of the chip itself and the performance of the PCB design and manufacture of the connection, so the packaging technology is critical.

Components packaging is the actual electronic components, such as chips, resistors, capacitors, etc., in a graphic representation of the PCB board in order to facilitate the PCB board for insertion or welding, will directly affect the performance of the circuit board, is the electronic manufacturing process is a vital part of the process.

Measure a chip packaging technology advanced or not is an important indicator: the ratio of the chip area to the area of the package, the closer this ratio is to 1 the better.

Based on the requirements of heat dissipation, the thinner the package, the better.

Encapsulation has gone through roughly the following development process:

Structure: TO → DIP → PLCC → QFP → BGA → CSP.

Material: metal, ceramic → ceramic, plastic → plastic.

Pin shape: long lead direct insertion → short lead or leadless mounting → ball bump.

Assembly method: through-hole insertion→surface assembly→direct mounting.

The following is an introduction to specific package forms:

1.SOP / SOIC package

SOP is the abbreviation of the English Small Outline Package, that is, the small outline package. SOP package technology developed by Philips in 1968 ~ 1969, and later gradually derived: SOJ, J-pin small outline package; TSOP, thin small outline package; VSOP, very small outline package; SSOP, reduced SOP; TSSOP, thin reduced SOP; SOT, small outline transistor; SOIC, small outline integrated circuit. SOP, reduced SOP; SOT, small outline transistor; SOIC, small outline integrated circuit.

2.DIP package

DIP is the abbreviation of ‘Double In-line Package’, i.e. Dual In-line Package. One of the plug-in package, the pins from both sides of the package, the package material has two kinds of plastic and ceramic.DIP is the most popular plug-in package, the application scope includes standard logic IC, storage LSI, microcomputer circuits and so on.

3.PLCC package

PLCC is the English ‘Plastic Leaded Chip Carrier’ abbreviation, that is, the plastic J-lead chip package. PLCC package, the shape of the square, 32-pin package, surrounded by pins, the external dimensions than the DIP package is much smaller. PLCC package is suitable for SMT surface mounting technology in the PCB mounting and wiring, with a small form factor, the advantages of high reliability.

4.TQFP package

TQFP is the abbreviation of ‘Thin Quad Flat Package’, i.e. thin plastic four corners flat package. Quad flat package process can effectively use the space, thus reducing the size of the printed circuit board space requirements. Because of the reduced height and size, this package process is ideal for space-critical applications such as PCMCIA cards and networking devices. Almost all of ALTERA's CPLD/FPGAs are available in TQFP packages.

5.PQFP Package

PQFP is the English ‘Plastic Quad Flat Package’ abbreviation, that is, the plastic quad flat package, PQFP package chip pin-to-pin distance is very small, the pin is very thin. General large-scale or ultra-large-scale integrated circuits in this package form, the number of pins are generally more than 100.

6.TSOP package

TSOP is the English ‘Thin Small Outline Package’ abbreviation, that is, thin small size package, TSOP memory packaging technology, a typical feature is to make pins around the packaged chip, TSOP is suitable for SMT (surface mounting) technology in the PCB mounting and wiring. TSOP package shape, parasitic parameters (when the current changes significantly, caused by the output voltage perturbation) is reduced, suitable for high-frequency applications, easier to operate, and higher reliability.

7.BGA Package

BGA is the English ‘Ball Grid Array Package’ abbreviation, that is, the ball grid array package. 1990s, with the advancement of technology, chip integration continues to improve, the number of I / O pins increased dramatically, the power consumption also increased, the requirements of the integrated circuit package is also more stringent. In order to meet the needs of development, BGA packaging began to be applied to production.

Memory packaged with BGA technology can increase the memory capacity by two to three times with the same memory volume. BGA has a smaller volume, better heat dissipation and electrical performance compared to TSOP. BGA packaging technology has improved the storage capacity per square inch, and memory products with BGA packaging technology are only one-third of the size of TSOP packages with the same capacity. In addition, compared with the traditional TSOP package, BGA package has a faster and more effective way to dissipate heat.

The I/O terminals of BGA package are distributed underneath the package in the form of round or columnar solder joints in the form of arrays. The advantage of BGA technology is that although the number of I/O pins has increased, the pin spacing has not been reduced but rather increased, thus improving the assembly yield. Although its power consumption increases, BGA can be soldered using the controlled collapse chip method, which can improve its electrical and thermal performance. Thickness and weight are reduced compared to previous packaging technology; parasitic parameters are reduced, the signal transmission delay is small, the use of frequency is greatly improved; assembly can be coplanar welding, high reliability.

8.TinyBGA package

Speaking of BGA packaging, we can not mention Kingmax's patented TinyBGA technology, TinyBGA English full name ‘Tiny Ball Grid’, belongs to a branch of the BGA packaging technology, was developed in August 1998 Kingmax success. 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 with the same volume of memory. Compared with TSOP package products, it has smaller volume, better heat dissipation performance and electrical performance.

Memory products with TinyBGA packaging technology are only 1/3 of the size of TSOP packages in the same capacity situation.The pins of TSOP packages are led out from the periphery of the chip, while TinyBGA is led out from the centre of the chip. This effectively shortens the signal conduction distance, as the length of the signal transmission line is only 1/4 of the traditional TSOP technology, thus reducing the signal attenuation. This not only significantly improves the chip's anti-interference and anti-noise performance, but also improves the electrical performance. TinyBGA packages can withstand external frequencies up to 300MHz, whereas traditional TSOP packages can only withstand external frequencies up to 150MHz.

TinyBGA package memory is also thinner (package height less than 0.8mm), the effective heat dissipation path from the metal substrate to the heat sink is only 0.36mm. Therefore, TinyBGA memory has a higher thermal conduction efficiency, which is very suitable for long-time running systems with excellent stability.

9. QFP Package

QFP stands for ‘Quad Flat Package’, i.e., a small square flat package. QFP packages were used more frequently in the early days of graphics cards, but there are few QFP packages with speeds above 4ns, and they have been gradually replaced by TSOP-II and BGA because of process and performance issues. QFP packages have pins all around the die and are fairly obvious to identify. Quad Side Pin Flat Pack. One of the surface mount packages with pins coming out of the four sides in a gullwing (L) shape.

There are three types of substrates: ceramic, metal and plastic. In terms of quantity, plastic packages account for the majority. When there is no special indication of the material, the majority of cases are plastic QFPs, which are the most popular multi-pin LSI packages used not only for digital logic LSI circuits, such as microprocessors and gate displays, but also for analogue LSI circuits, such as VTR signal processing and acoustic signal processing. The pin centre distance is 1.0mm, 0.8mm, 0.65mm, 0.5mm, 0.4mm, 0.3mm and other specifications, and the maximum number of pins in the 0.65mm centre distance specification is 304.