Solder Balls; Pick And Place Cover - Intel BX80605X3440 - Quad Core Xeon X3440 Reference

3.4.2

Solder Balls

A total of 1156 solder balls corresponding to the contacts are on the bottom of the
socket for surface mounting with the motherboard. The socket solder ball has the
following characteristics:
• Lead free SAC (SnAgCu) 305 solder alloy with a silver (Ag) content between 3%
and 4% and a melting temperature of approximately 217 °C. The alloy must be
compatible with immersion silver (ImAg) and Organic Solderability Protectant
(OSP) motherboard surface finishes and a SAC alloy solder paste.
The co-planarity (profile) and true position requirements are defined in
3.4.3 Contacts
Base material for the contacts is high strength copper alloy.
For the area on socket contacts where processor lands will mate, there is a 0.381 μm
[15 μinches] minimum gold plating over 1.27 μm [50 μinches] minimum nickel
underplate.
No contamination by solder in the contact area is allowed during solder reflow.
3.4.4

Pick and Place Cover

The cover provides a planar surface for vacuum pick up used to place components in
the Surface Mount Technology (SMT) manufacturing line. The cover remains on the
socket during reflow to help prevent contamination during reflow. The cover can
withstand 260 °C for 40 seconds (typical reflow/rework profile) and the conditions
listed in Chapter 5
As indicated in
should remain on whenever possible to help prevent damage to the socket contacts.
Cover retention must be sufficient to support the socket weight during lifting,
translation, and placement (board manufacturing), and during board and system
shipping and handling. Covers can be removed without tools.
The socket vendors have a common interface on the socket body where the PnP cover
attaches to the socket body. This should allow the PnP covers to be compatible between
socket suppliers.
As indicated in
proper orientation with the socket.
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without degrading.
Figure 3-6, the cover remains on the socket during ILM installation, and
Figure 3-6, a Pin1 indicator on the cover provides a visual reference for
Thermal/Mechanical Specifications and Design Guidelines
LGA1156 Socket
Appendix C.