This standard on spherical transient bend testing is intended to characterize the maximum allowable strain that a surface mount component's board level interconnects can withstand in flexural loading. Whereas four-point monotonic bend test methods only address simple planar bending, spherical bend tests establish strain limits of board level interconnects under worst-case flexure conditions that can occur during conventional printed board/system assembly, manufacturing and test operations. This method is applicable to surface mounted BGA components larger than 15.0 mm on a side with organically based substrates, attached to printed boards using conventional solder reflow technologies. This document was developed cooperatively with JEDEC.
Semiconductor devices are assembled in a variety of package configurations and are used in a multitude of applications. Given the diversity of package and printed board layouts, as well as end-use conditions, it is not feasible to establish a single strain limit requirement related to spherical transient bend testing for all package sets and printed board configurations. However, a maximum allowable strain limit specific to a particular Printed Circuit Assembly (PCA) may be established using the method discussed in this standard. In addition, non-experimental analysis techniques, such as finite element simulation, may also be used in conjunction with testing to define strain limits for an expanded envelope of printed board and package attributes. A four-point monotonic bend test methodology is detailed in IPC/JEDEC-9702; this methodology enables the characterization of the fracture strength due to flexural loading of a surface mount component’s board level interconnects. The four-point bend test method only addresses simple planar bending and may not reflect more complex and damaging bend modes that a PCA undergoes in the manufacturing and assembly process. This standard establishes a spherical bend test method that envelopes maximum strain levels for manufacturing, assembly, and handling flexure events, enabling the determination of maximum strain levels to be used as guidance during those events.