BGA, or Ball Grid Array, is a type of surface-mount package used in making electronic circuits. It is often used when electronic components are mounted directly on the Printed Circuit Board’s (PCB) surface. The BGA is derived from the PGA (Pin Grid Array), an older type of surface-mount package.
What is the Use of BGA? (or How is BGA mounted?)
The PGA mounts with pins on a circuit board. The pins emit electrical signals that appear from integrated circuits and goes to the PCB on which they are mounted.
In BGA, solder balls at the base of its package substitute pins. The apparatus is, therefore, on the PCB that holds copper pads in a blueprint that matches the solder balls. Its assembly heats in reflow ovens or in the infrared heater, and this causes the solder balls to melt. Exterior tension then causes the liquefied balls to align the package to the circuit board, on its correct distance of separation, as the solder begins to cool as it solidifies.
Advantages of BGA
- High Density – BGA is one answer to the production of a mini package for the integrated circuit with many pins. PGA and SOIC or Dual-in-line surface mount are produced pins. When more pins are required, the space between them is reduced. This causes difficulty for the soldering process. As its package pins go closer, the incidence of accidents in the bridging of pins with the solder grows. BGAs do not have this problem, as the solder used are factory-applied package at the precise amount.
- Heat Conduction – Another advantage of a BGA package is the low thermal resistance it has between its package and its PCB. This allows heat made by the integrated circuit inside its packages to flow with ease to the PCB, thereby preventing it from overheating.
- Low-Inductance Leads – Shorter electrical conductors mean it has a lower inductance, a property that causes unwelcome distortion signals in high-speed circuits. A BGA, with its short distance between packages and the PCB, have very low inductances.
Disadvantages of BGA
- Noncompliant leads – Solder balls that cannot flex are a problem for BGA. As with surface mount devices, bending due to the difference in the coefficient of its thermal expansion from the PCB substrates and the BGA, or its flexing and vibration, can cause the joints to fracture.
- Expensive Inspection – Once the package is soldered, checking solder faults becomes very difficult. X-ray machines and other special microscopes are being developed to overcome this troublesome process, but the costs are very high. If the BGA is badly soldered, it is transferred to the rework station and inspected with the use of an infrared lamp.