Singlestone
PBA 313 07
Preliminary Product Overview
4/2004
19
4
Assembly and design guidelines
4.1 General description of the module
Singlestone is a Land Grid Array (LGA 8x9) module made for surface mounting. The pad diameter is
0.8 mm and the pitch 1.27 mm.
All solder joints on the module will reflow during soldering on the mother board. All components and
shield will stay in place due to wetting force.
Surface treatment on the module pads is Nickel /Gold.
Figure 1 shows the pad layout on the module, Seen from component side.
Figure 4-1 Pad layout on the module (top view)
4.2 Printed Circuit Board design
The land pattern on the PCB shall be according to the land pattern on the module, which means that
the diameter of the LGA pads on the PCB shall be 0.8 mm. It is recommended that each pad on the
PCB shall be surrounded by a solder mask clearance of about 75 µm to avoid overlapping solder
mask and pad.
The solder pads must have wetability to eutectic solder. Electroless Ni/Au plating or OSP (Organic
Surface Protection) is a common surface finish and is suitable for assembly.
4.3 Solder paste printing
The solder paste deposited on the PCB by stencil printing has to be of eutectic or near eutectic tin
lead composition (e.g. 63Sn37Pb or 62Sn36Pb2Ag). A no-clean solder paste is preferred, because
cleaning of the solder joints which are under the module is difficult.
Preferred thickness of the solder paste stencil is 100 - 127 µm (4 - 5 mils). The apertures on the solder
paste stencil shall be of the same size as the pads, 0.8 mm.
