Figure 3-8. Contact Force Versus Contact Deflection Range
Order Number: 334785-002 Intel
®
Xeon
®
Phi™ Processor x200 Product Family TMSDG
29
Socket Mechanical Design
3.3.4 Solder Ball Characteristics
• Solder Ball Count - The total number of solder balls is 3647.
• Layout - The solder balls are laid out in two “C” shaped regions, as shown in
Appendix D.
• Material - Lead free SAC (SnAgCu) solder alloy with a silver content between 3%
and 4%, with a melting temperature of approximately 217 °C will be used. The
alloy will be compatible with standard Lead free processing such as immersion
silver and Organic Solderability Preservatives (OSP) main board Surface Mount
Technology (SMT) applications as well as a SAC alloy solder paste.
• Co-Planarity - The co-planarity (profile) requirement for
all solder balls on the
underside of the socket is defined in Appendix D. The specification is applicable to
all temperature ranges when surface mounting the socket onto the main board.
• True Position - The solder ball pattern has a true position requirement with respect
to
applicable datum in order to mate with the main board land pattern. Refer to
Appendix D for details.
3.3.4.1 Solder Ball Wetting Angle for Paddle Design
To minimize the risk associated with shock, vibration, and transient bend stresses, the
solder ball wetting angle must be controlled via ball attach process optimization such
that the post SMT wetting angle defined in Figure 3-9 is less than or equal to 90
degrees. In the event that a correlation can be identified between wetting height (also
define
d in Figure 3-9) and wetting angle, the wetting height may also be used as a
measurable success criterion.
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