The BGA concept increasingly popular. The so-called BGA is refers to the components of the contact neither lead nor pin, but the connection at the bottom of the device into an array like very small (diameter of 0.8mm) tin / lead alloy ball, pitch 1.5mm (0.060 inches), accordingly to provide reliable connection. This style of components not only for the single chip connection is ideal, and the high performance multi chip module (MCM) connection is also very reliable.
Very small diameter of tin / lead alloy ball instead of lead means can be removed by the lead coplanarity and skew caused most of the problems. With the increase of the number of I / O, BGA is not simply towards more and more fine pitch, but the use of contact spacing book of slightly larger than the fine pitch device spacing.Jedec note 1.0,1.27,1.5mm. currently being launched 1.27 and 1.5mm pitch instead of 0.5 ~ 0.4 mm fine pitch devices.
These components single chip and multi chip structure. This technique can be the I / O expansion to more than 1000. Estimated that at the end of this century, the future all ASIC applications will have 50% for 200 or more than 200 i/o. use of fine pitch devices, its fine wire is easy to damage and is extremely fine accurate placement and strict lead coplanarity.
There are three types of BGA. Another advantage of BGA assembly is adapted to existing SMT assembly process and equipment, that can use existing solder paste screen printing equipment, pick and place equipment and reflow soldering equipment. Due to the BGA average wirelength than equivalent I / O assembly line length, so it has better electrical characteristics.