Many types of IC, such as logic chips, memory chips, MCU or FPGA are exposed to daily work as an electronic engineer; the functional characteristics of various types of IC may be much clearer, but how much is known about the packaging of the IC?
This article will introduce the packaging principles and functional characteristics of some commonly used ICs. By understanding the packaging of various types of ICs, electronic engineers can accurately select ICs when designing the principles of electronic circuits.
I. DIP (dual in-line package)
DIP refers to integrated circuit chips that are packaged in dual in-line form. Most small and medium-sized integrated circuits (ICs) use this package form. The number of pins generally does not exceed 100. The DIP packaged IC has two rows of pins and needs to be inserted into a chip socket with a DIP structure. Of course, it can also be directly inserted into a circuit board with the same number of solder holes and geometrical arrangement for soldering. When inserting and removing the DIP packaged chip from the chip socket, special care should be taken to avoid damaging the pins.
DIP package has the following characteristics:
1. Suitable for through-hole welding on PCB (printed circuit board), easy to operate.
2. The ratio between the chip area and the package area is large, so the volume is also large.
3. DIP is the most popular plug-in package, and its applications include standard logic ICs, memories, and microcomputer circuits.
Figure 1: DIP package
Ⅱ. QFP (Quad Flat Package)
The distance between the pins of a QFP package is very small and the pins are very thin. Generally, large-scale or very large-scale integrated circuits use this package. Chips packaged in this form must be soldered to the motherboard using SMD (Surface Mount Device Technology). Chips installed with SMD do not need to punch holes in the motherboard. Generally, there are solder joints of corresponding pins on the surface of the motherboard. Align the pins of the chip with the corresponding solder joints to achieve soldering to the motherboard.
The QFP package has the following characteristics:
1. Suitable for SMD surface mounting technology.
2. Low cost, suitable for low and medium power consumption, suitable for high frequency use.
3. Easy operation and high reliability.
4. The ratio between the chip area and the package area is small.
5. Mature package types can use traditional processing methods.
At present, QFP packages are widely used, and many MCU manufacturers' chips use this package.
Figure 2: QFP package
Ⅲ. BGA (Ball Grid Array Package)
With the development of integrated circuit technology, packaging requirements for integrated circuits have become more stringent. This is because the packaging technology is related to the functionality of the product. When the frequency of the IC exceeds 100MHZ, the traditional packaging method may produce the so-called "CrossTalk" phenomenon, and when the number of IC pins is greater than 208 Pins, the traditional packaging method has its difficulty. Therefore, in addition to the QFP packaging method, most high-pin count chips today are converted to BGA (BALL Grid Array PACKAGE) packaging technology.
The BGA package has the following characteristics:
1. The contact surface between the BGA array solder ball and the substrate is large and short, which is good for heat dissipation.
2. The pins of BGA array solder balls are very short, which shortens the signal transmission path and reduces lead inductance and resistance.
3. The signal transmission delay is small, and the adaptive frequency is greatly increased, so the performance of the circuit can be improved.
4. Assembly can be coplanar welding, greatly improving reliability.
5. BGA is suitable for MCM (Multichip Module) package, which can realize high density and high performance of MCM.
Figure 3: BGA package
Ⅳ. SO (Small Out-Line Package)
SO type packages include: SOP (small outline package), TOSP (thin small outline package), SSOP (Shrink Small-Outline Package), VSOP (very small outline package), SOIC (small outline integrated circuit package), etc. This package similar to the QFP package, but with only two sides of the chip package, this type of package is one of the surface-mount packages, and the pins are drawn out from both sides of the package in an "L" shape.
The typical characteristic of this type of package is to make pins on both sides of the packaged chip. The package operation is convenient and the reliability is high. It is one of the current mainstream packaging methods. At present, it is more commonly used in some memory-type ICs.
Ⅴ. QFN (Quad Flat No-lead Package)
QFN is a lead-free package with peripheral termination pads and a chip pad for mechanical and thermal integrity exposure.
The package can be square or rectangular. There are electrode contacts on the four sides of the package. Since there are no pins, the mounting area is smaller than that of QFP and the height is lower than that of QFP.
QFN package features:
1. Surface mount package, leadless design.
2. Leadless pad design occupies smaller PCB area.
3. The components are very thin (<1mm), which can meet the applications with strict space requirements.
4. Very low impedance and self-inductance, which can meet high-speed or microwave applications.
5. Has excellent thermal performance, mainly due to the large area of the thermal pad on the bottom.
6. Lightweight for portable applications.
The small form factor of QFN packages can be used in portable consumer electronics such as notebook computers, digital cameras, personal digital assistants (PDAs), mobile phones and MP3s. From the perspective of the market, QFN packaging has attracted more and more attention from users. Considering factors such as cost and volume, QFN packaging will be a growth point in the next few years and the development prospect is extremely optimistic.
Ⅵ. PLCC (Plastic Leaded Chip Carrier)
PLCC is a form where the leads are drawn from the four sides of the package and are in the shape of a "T". The PLCC package is suitable for surface mounting technology, and has the advantages of small size and high reliability.
PLCC is a special pin chip package. The pins of this package are bent inward at the bottom of the chip, so the chip pins are not visible in the top view of the chip. This type of chip is soldered using a reflow process, which requires special soldering equipment. It is also very troublesome to remove the chip during debugging. It is now rarely used.
Figure 6: PLCC package
