Land Grid Array, LGA Package
Land Grid Array Graphic
LGA [Land Grid Array] is a surface mount package that uses pads to attach to solder balls located on the Printed Wiring Board [PWB]. An LGA package differs from a BGA in that a BGA has the solder-balls attached to the package while an LGA uses solder-balls that are attached to the printed circuit board.
As with any other IC package the size of the device varies with the number of pins, or terminals in this case, which are attached to the component. Because an LGA could be any size the dimensions for the graphic above are not provided. However the graphic does show how to count the pad locations, which is the same pattern sequence used in a BGA.
AMD Athlon 64 FX-70 series processor
In addition the terminal grid array may take on any shape, or omit terminals, just as a BGA package may omit pins. So both the LGA graphic and picture show a completed grid array, but that does not have to be the case.
At first glance the LGA may appear thinner than a BGA, but once the LGA is attached to the solder balls that reside on the printed wiring board, the relative height of the LGA should be about the same as a BGA [which already had the solder balls attached].
In fact the basic physical dimensions for a an LGA package could be the same as a column grid array or ball grid array package, as the only thing that is changing is the mounting terminals or pads. A Ceramic Land Grid Array [CLGA] is identical to any LGA package except for the fact that the body of the component is made of ceramic and not plastic or some other material.
Many types of heat sinks are available for LGA packages. In general there will be two main types of heat sinks, one that clips to the IC package or the printed wiring board or one that is glued to the top of the LGA surface. The example shown above is but one version of a heat sink that would be attached to the top surface of the metal lid using Thermal Adhesive.
Another example of a package with ICs installed on the package; BGA Processor ICs.
