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Few words about SMD-Surface Mount components

2017-12-22 19:01  
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Today electronics is shifting to SMT (Surface Mount Technology) or SMD (Surface Mount Devices) area. DIP domination has left behind.

DIP_DIL14 photo

They wona€?t be vanished from electronics industries as there many areas where they are and will be successfully used. But as electronic circuit complexity grows, demand on PCB miniaturization increases there is no other way as to use SMD technology to achieve these goals.

I bet Electronic hobbyists noticed that it is harder to find some particular electronic elements in DIP packages. Many microcontroller types are released only in SMT packages like Atmega128- QFP64, LPC2000 microcontroller series in LQFP package series. I dona€?t talk about bigger IC like AVR32 or FPGA where BGA packages comes with 672 connection balls.

This situation pushes all us to other level of prototyping. Many of electronic designers and hobbyists are using SMT quite a long time as they see benefits of it. The rest through-hole technology lovers have to accept and manage the SMT. There is nothing difficult up to some level. Probably you have tried to solder SMD resistor or some SOIC IC. It may look difficult at a first glance but some patience and you will master this.

Leta€?s go through some popular SMD devices and see how do they look like and how to deal with them.

SMD resistorscome in to several package types and sizes. Each size is describes as four digit number. First two digits indicate the length and last two a€“ width (in 0.01a€? or 10 mils units). For instance:

  • 0603: means 0.06″x0.03″, or 60×30 mils, or 1.6×0.8mm
  • 0805: means 0.08″x0.05″, or 80×50 mils, or 2.1×1.4mm
  • 1206: means 0.12″x0.06″, or 120×60 mils or 3.2×1.6mmsmd resistors

    SMD capacitors from 1pF to 1uF come in same sizes as SMD resistors: 0603 to 1206. Usually they are ceramic capacitors.

    CAP_SMD 0805

    Other types of capacitors are tantalum SMD capacitors. They come from 1uF and they are polarized (positive side indicate by bar sign). Their sizes are indicated by letters from a€?Aa€? to a€?Ea€?:

    Case

    L x W x H (mm)

    A

    3.2×1.6×1.6

    B

    3.5×2.8×1.9

    C

    6.0×3.2×2.5

    D

    7.3×4.3×2.8

    E

    7.3×6.0×3.6

    Following picture helps to indicate tantalum capacitors and other types:

    SMD_capacitors

    1. Tantalum; 2. Tantalum; 3. Electrolytic Capacitor; 4. Electrolytic Capacitor; 5. 0805 Ceramic; 6. 1206 Ceramic; 7. 1210 Ceramic; 8 . High Q Porcelin RF; 9. Variable Trimmer; and 1/4 Watt leaded resistor as reference

    SMD transistors mostly come in two popular packages SOT-23 and SOT-223:SOT23.JPG>>>>>>>>>>>>sot23_pnp.JPG

    Integrated circuits can be in various packages:

    Dual in line:SOIC; TSOP; SSOP; TSSOP; VSOP.

    Quad in line:PLCC; QFP; LQFP; PQFP; CQFP; TQFP; QFN; PQFN.

    Grid arrays:BGA; LFBGA; CGA; CCGA; ??BGA; LLP.

    Non packaged devices:COB; COF; COG; MLP; MQFP.

    Photo-SMDchips

    There are various soldering techniques of SMD chips. Simplest one is by using regular solder iron a€“ better with temperature regulator to maintain constant temperature. Just use a lot of flux to avoid solder bridges between pins and helps to make quality soldering joints.

    For bigger ICa€?s it is better to use hot air solder or even heat oven. Do not afraid to experiment.


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