The firmware is for India Standard iPhone 4S. Application will be available at iTunes App StoreA typical electrical device, such as a cellular telephone, may include a printed circuit board (PCB) on which various components are mounted to form an electrical package for mounting on a surface of a PCB. One type of electrical package is a ball grid array (BGA) package, in which a large number of contacts, such as solder balls or pins, are arranged in a two-dimensional array on the bottom surface of the package to form an array of contacts. The contacts are soldered to corresponding conductive lands of a PCB so that the contacts are electrically and mechanically connected to the PCB.
Because of the high-density contacts of a BGA package, the conductive paths between the contacts are very short. This can reduce the capacitance between the contacts, and therefore increase the speed of the electrical package. It may also prevent noise from traveling along the conductive paths between the contacts, and reduce the number of high-frequency or otherwise undesired electrical signals that are received by the contacts.
One type of electrical package is a chip scale package (CSP) package, in which a chip (or die) is mounted directly on the PCB. In the CSP package, the contacts of the electrical package are arranged in a two-dimensional array on a bottom surface of the package, which is substantially the same size as the chip. The contacts are conductive to the contacts of the PCB so that the contacts are electrically and mechanically connected to the PCB.
Because of the very short electrical conductive paths between the contacts of a CSP package, the capacitance between the contacts is reduced as compared to the capacitance in a BGA package. Consequently, the contacts of a CSP package may operate at higher speeds. It may also provide more and shorter conductive paths between the contacts, so that the CSP package may receive and transmit more high-frequency electrical signals.
Although CSP packages may be electrically and mechanically connected to a PCB in many different ways, one way is to use a CSP package with a BGA package. A BGA package may include a CSP package and a BGA package. In this configuration, the CSP package may be mounted to the BGA package so that the contacts of the CSP package are electrically connected to the contacts of the BGA package.
In a typical CSP-BGA package, the CSP package is first mounted to the PCB
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