SMT involves a wide variety of parts and styles, many of which have formed become industry-wide standards. These are mainly chips, capacitors, resistors, and other types of components. Many are still undergoing constant changes. This is especially true for IC parts. The changes in its packaging form are endless, and the traditional pin package is making way for new generation of packaging (e.g. BGA and FLIP CHIP).
Standard parts are gradually formed during the development of SMT, mainly for relatively large parts. This section only describes common standard parts. Currently, there are mainly the following types:
- resistors (R)
- Inductor (L)
- Ceramic capacitor (C)
- Discharge capacitor (CP)
- Tantalum capacitor (C)
- Diode (d)
- Transistor (Q)
The type of parts can be determined on the PCB according to the code. In general, the part the code corresponds to the actual part that is loaded.
1. The part specifications:
The part specifications, that is, the external dimensions of the parts, for SMT has been developed as an industry standard for parts series. All parts suppliers manufacture according to these standard.
The size specifications of standard parts are expressed in Imperial and metric, as follows:
- Metric representation: 1206 0805 0603 0402
- Imperial representation: 3216 2125 1608 1005
In the development of SMT, with the continuous improvement of electronic product integration, standard parts have gradually become smaller. Now the smallest standard parts have reached 0201, 01005.
2. Common component packaging
The most common ones are 0805, 0603. The difference is that it can appear as an exclusion.
Can be divided into two categories: non-polar and polar.
There are polar capacitors, which are what we usually call electrolytic capacitors. Generally, the most commonly used are aluminum electrolytic capacitors. Their temperature stability and accuracy are not very high. These chip components are close to the circuit board, so many cases require the temperature stability to be high. For these cases, the chip capacitor has more tantalum capacitors. According to the different rated voltages, the chip capacitors can be divided into different series.
For more information on Capacitors, check out our article: The Guide to SMT Material Packaging: Chip Resistor
According to the limits of the current, the package form is divided into two categories.
The small current type (such as 1N4148) is packaged at 1206.
High current type (such as IN4007) specific size: 5.5 X 3 X 0.5
Light-emitting diodes: the colors are red, yellow, green, and blue. The brightness levels are in ascending from red to blue.
There are three types of commonly used packaging: 0805, 1206, 1210
Basic IC types
SOP (Small Outline Package):
The parts have feet on both sides and the feet are flared outwards (generally called gull wing type pins).
SOJ (Small Outline J-lead package):
The part has feet on both sides and the foot is bent toward the bottom of the part (J-type pin).
QFP (Quad Flat Package):
The parts have feet on four sides, and the parts are opened outwards.
PLCC (Plastic Leadless Chip Carrier):
The parts have feet on four sides, and the parts are bent to the bottom of the parts.
BGA (Ball Grid Array):
The surface of the part has no feet, and the feet are arranged in a spherical matrix at the bottom of the part.
CSP (CHIP SCAL PACKAGE):
Part size packaging.
There are many other categories of components that can be used in the SMT process. We'll discuss more of these as we move along in this series.
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To learn more about SMT materials check out the links below
For more articles on SMT soldering, techniques and red glue, check out the links below