BGA or Ball Grid Array – Illustrated Guide

BGA or Ball Grid Array is one type of packaging for surface-mounted PCBs (where components are actually 'mounted' or affixed on the surface of the printed circuit board). A BGA package simply looks like a thin wafer of semi-conducting material that has circuit components on only one face. The Ball Grid Array package is called such because it is basically an array of metal alloy balls arranged in a grid. These BGA Balls are normally Tin/Lead (Sn/Pb 63/37) or Tin/Lead/Silver (Sn/Pb/Ag)

There is another common packaging for integrated circuits and this is the PGA or Pin Grid Array. The BGA looks physically similar to a Pin Grid Array package. Both are one-sided; that is, only one face of the semi-conducting substrate is used for printing and mounting of circuit components. Both have an obvious grid-like pattern. However, the Pin Grid Array uses pins - thus, the name - whereas the BGA uses balls - as it has already been mentioned above. The pins (in the PGA) or the balls (in the BGA) are the materials through which electricity is conducted between the printed surface of the semiconductor board and the surface-mounted circuit components.

A Ball Grid Array makes precise alignment and mounting possible. Before the Ball grid Array packaging, a single circuit board would sometimes require hundreds of pins. This presented a lot of positioning problems. When the assembly was heated, adjacent pins would sometimes get soldered together or form unplanned bridges that demanded for rework thus increasing the production time.

Another advantage of Ball Grid Array packaging over other types of packaging involves heat conduction. A Ball Grid Array has less resistance to heat so heat flows readily from the mounted circuit components to the printed circuit board. This reduces the risk of overheating or damage.

Finally, a Ball Grid Array assembly's contact points (point of contact between the surfaces solder balls and the printed circuit board itself) is not readily apparent. This means greater data and application security.

A Ball Grid Array packaged integrated circuit is rather inflexible. Rigorous stress on the integrated circuit may cause the balls or the contact points to break off. Furthermore, if flaws in design or construction need to be found, expensive tools would be needed.