A variety of electronic devices through the surface packaging process assembled on the circuit board. Next is box assembly, will assemble the PCB with the shell and so on to assemble, forms the finished product.
PCBA is the English printed circuit board +assembly abbreviation, that is, in the PCB empty board first through the SMT (Surface Mount Technology) on the piece, PCBA and then through the dip (double row of direct-insert packaging technology) plug-in production process.
Basic materials for PCBA
Substrate is generally based on the insulating part of the substrate classification, the common raw materials for the board, Glass fiberboard, and all kinds of plastic board. and PCB manufacturers will generally take a glass fiber, nonwoven materials, PCBA as well as resin insulation part, and then epoxy resin and copper foil as "bonding piece" (prepreg) used.
and the common base material and main ingredient are:
fr-1── Phenolic cotton paper, this substrate is commonly known as bakelite (higher cost than FR-2)
fr-2── Phenolic cotton paper,
fr-3── Cotton paper (cottpaper), epoxy resin
fr-4── Glass Cloth (woven glass), epoxy resin
fr-5── glass cloth, epoxy resin
fr-6── Surface Glass, polyester
g-10── glass cloth, epoxy resin
cem-1── cotton paper, epoxy resin (flame retardant)
cem-2── cotton paper, epoxy resin (non-flame retardant)
cem-3── glass cloth, epoxy resin
cem-4── glass cloth, epoxy resin
cem-5── glass cloth, poly ester
ain── Aluminum Nitride
Brief description of PCBA operations
SMT and dip are on the PCB board integrated parts of the way, the main difference is that SMT does not need to PCB on the drilling, PCBA in the dip need to insert the pin foot of the parts have been drilled into the hole.
SMT (Surface Mount Technology)
Surface mount Technology, the main use of the installation is a number of small parts affixed to the PCB board, the production process is: PCB board positioning, printing solder paste, SMT installation, over-back welding furnace and made inspection. With the development of science and technology, SMT can also carry out some large-size parts of the mount, such as the motherboard can be affixed to some larger size of the body parts. SMT integration is sensitive to positioning and the size of the parts, PCBA in addition to the quality of solder paste and printing quality also play a key role.
Dip (double row direct-insert package technology)
Dip is "plug-ins", that is, in the PCB version of the insert parts, because the size of the parts are large and not suitable for mounting or the production process of the manufacturer can not use SMT technology when using the form of plug-in integration parts. At present, PCBA there are artificial plug-ins and robot plug-ins in the industry, the main production process is: Paste back glue (to prevent tin plating to the place where it should not be), plug-ins, testing, over wave soldering, brush version (removal of stains left in the process) and made to test.
The PCBA may lead to rejection.
Blow hole/pinhole, solder paste back?? Completely, solder does not wetting to the need to weld the disc or terminal, solder coverage does not meet the requirements, the reverse wetting phenomenon caused by welding does not meet the surface mount or through the hole of the solder filling requirements, the tin ball violates the minimum electrical clearance, crosses the solder connection on the conductor which should not be connected, PCBA the solder crosses to the adjacent non-common conductor or the original, the solder is disturbed, the violent, does not follow the stipulation to choose the correct component, the component is not installed in the correct hole and so on.
PCBA Product Status
As the production of PCBA is in the latter half of the electronic equipment, it is the downstream industry of the electronics industry. Almost all electronic devices require support, so printed circuit boards are the world's largest market share of electronic components products. At present, Japan, China, Taiwan, PCBA Western Europe and the United States as the main production base of printed circuit board.