Ball Grid Array or BGA is a surface-mount package (with no leads) utilizing an array of metal spheres (solder balls) for electrical interconnection. BGA solder balls are attached to a laminated substrate at the bottom of the package. The die of the BGA is connected to the substrate by wire bonding or flip-chip technology. The BGA substrate has internal conductive traces that route and connect the die-to-substrate bonds to the substrate-to-ball array bonds.
BGA is soldered on to the printed circuit board using a reflow oven. As the solder balls melts in the reflow oven, the surface tension of the molten solder ball keeps the package aligned in its proper location on the circuit board, until the solder cools and solidifies. Proper and controlled soldering process and temperature is essential for good solder joints and to prevent solder balls from shorting with each other.
Advantages of Ball Grid Array (BGA) Packaging
Ball Grid Array (BGA) offers several advantages over other electronic components. The most important advantage of BGA packaging for integrated circuits is its high interconnection density. BGA packages also lesser space on the circuit board.
Assembly of Ball Grid Array onto circuit boards is more efficient and manageable than its leaded counterparts because the solder needed for soldering the package onto the circuit board come from the solder balls itself. These solder balls also ‘self-align’ themselves during mounting
Lower thermal resistance between BGA Package and the circuit board is another advantage of Ball Grid Array packaging. This allows heat to flow more freely resulting in better heat dissipation and prevents the device from overheating.
BGA also offers better electrical conductivity because of shorter path between the die and the circuit board.
Disadvantages of BGA
Like all other electronic packages, BGA too, have some drawbacks. Following are some of the disadvantages of BGA:
BGA packages are more prone to stress because of flexural stress from the circuit board leading to potential reliability issues.
Inspecting of solder balls and solder joints for defects is very difficult once the BGA has been soldered onto the circuit board.