LGA1155 Socket
3.3Socket Components
The socket has two main components, the socket body and Pick and Place (PnP) cover, and is delivered as a single integral assembly. Refer to Appendix C for detailed drawings.
3.3.1Socket Body Housing
The housing material is thermoplastic or equivalent with UL 94
The color of the housing will be dark as compared to the solder balls to provide the contrast needed for pick and place vision systems.
3.3.2Solder Balls
A total of 1155 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 is compatible with immersion silver (ImAg) and Organic Solderability Protectant (OSP) motherboard surface finishes and a SAC alloy solder paste.
•Solder ball diameter 0.6 mm ± 0.02 mm, before attaching to the socket lead.
The
3.3.3Contacts
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.
3.3.4Pick 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 without degrading.
As indicated in Figure
Thermal/Mechanical Specifications and Design Guidelines | 23 |