scope:

This part of IEC 61191 specifies the evaluation criteria for voids on the scale of the thermal cycle life, and the measurement method of voids using X-ray observation. This part of IEC 61191 is applicable to the voids generated in the solder joints of BGA and LGA soldered on a board. This part of IEC 61191 is not applicable to the BGA package itself before it is assembled on a board.

This standard is applicable also to devices having joints made by melt and re-solidification, such as flip chip devices and multi-chip modules, in addition to BGA and LGA. This standard is not applicable to joints with under-fill between a device and a board, or to solder joints within a device package.

This standard is applicable to macrovoids of the sizes of from 10 μm to several hundred micrometres generated in a soldered joint, but is not applicable to smaller voids (typically, planar microvoids) with a size of smaller than 10 μm in diameter.

This standard is intended for evaluation purposes and is applicable to

− research studies,

− off-line production process control and

− reliability assessment of assembly.