PCB Standards and Specifications
What is PCB Assembly?
A circuit board prior to assembly of electronic components is known as PCB. Once electronic components are soldered, the board is called Printed Circuit Assembly (PCA) or Printed Circuit Board Assembly (PCBA) or PCB Assembly. Different Manual and Automatic PCB Assembly Tools are used in this process.
It has to be noted that assembly of a circuit board is different from PCB Manufacturing Process. Manufacturing printed circuit boards involve several processes including PCB designing and creating PCB prototype. Once a PCB is ready, Active and Passive Electronic Components need to be soldered onto it before it can be used in any electronic equipment or gadget. This assembly of electronic components depends on Type of Printed Circuit Board, type of electronic components and purpose of the circuit board.
Things Needed for Printed Circuit Board Assembly
Following PCB Assembly Tools, electronics parts and consumables are needed for PCB assembly –
- Printed Circuit Board
- Basic Electronic components
- Soldering materials including solder wire, solder paste, solder bar, solder balls for BGA, solder preforms (depending on the type of soldering to be done)
- Soldering flux
- Soldering equipment including soldering station, wave soldering machine, SMT equipment, inspection and testing equipment etc.
Once all of the above equipment, electronic parts and all raw materials are arranged, it is time to start the printed circuit board assembly process.
Printed Circuit Board Assembly with Thru-Hole Electronic Components
Electronic components that have leads coming out and are inserted through tiny holes in the PCB for soldering are called thru-hole electronic components.
The assembly or soldering process for these components include wave soldering and hand soldering.
Wave Soldering – A PCB assembly process in which solder in the form of solder bar are put in a high-temperature bath. This solder remains in the bath in molten form and forms a wave at very high temperature. The range of temperature depends on the type of solder. Traditional tin / lead (Sn/Pb) solder has lower melting point than lead-free (Pb-Free) solder. The PCB with all the thru-hole electronic components in holes is passed over molted solder with a help of a conveyor belt.
The whole wave soldering PCB Assembly Process includes following steps:
- Inserting of electronic components
- Flux application
- Wave Solder
Once the wave soldering is done, the PCBA is cleaned and tested. If any fault or solder joint defect such as Pin Hole or Blow Hole Wave Soldering Defect is found, it is sent for rework, which is generally done by hand.
Hand Soldering is done in manufacturing units with less work load or in rework / repair jobs. A good quality soldering station or soldering iron and solder wire and flux are used in the process.
Surface Mount Technology (SMT) for Printed Circuit Board Assembly
Surface Mount Technology or SMT is a PCB assembly process for SMD electronic components. SMD components don’t have leads or legs. They are mounted on the surface of the circuit board. The equipment, electronic components and other soldering material used in this assembly process is different from thru-hole soldering process.
PCB Assembly Process Flow Chart (PCBA Process)