Electrical Requirements
R
18 mPGA604 Socket
Mechanical Design Guide
Table 4-2. Definitions (Sheet 2 of 2)
4 Maximum Average Contact
Resistance. Refer to Table 4-1,
Item 4
The max average resistance target is originally
derived from max resistance of each chain
minus resistance of shorting bars divided by
number of pins in the daisy chain. This value
has to be satisfied at all time. Thus, this is the
spec valid at End of Line, End of Life and etc.
Socket Contact Resistance: The resistance
of the socket contact, interface resistance to
the pin, and the entire pin to the point where
the pin enters the interposer; gaps included.
5 Measurement frequency(s) for
capacitance.
Capacitively dominate region. This is usually
the lowest measurable frequency. This should
be determined from the measurements done
for the feasibility.
6 Measurement frequency(s) for
inductance.
Linear region. This is usually found at higher
frequency ranges. This should be determined
from the measurements done for the feasibility.
4.1 Electrical Resistance Figure 4-1and Figure 4-2 show the proposed methodology for measuring the final electrical
resistance. The methodology requires measuring interposer flush-mounted directly to the
motherboard fixtures, so that the pin shoulder is flush with the motherboard, to get the averaged
jumper resistance, Rjumper. The Rjumper should come from a good statistical average of 30
package fixtures flush mounted to a motherboard fixture. The same measurements are then made
with a package fixture mounted on a supplier’s socket, and both are mounted on a motherboard
fixture; this provides the RTotal. The resistance requirement, RReq, can be calculated for each chain as
will be explained later.
Figure 4-1. Methodology for Measuring Total Electrical Resistance.
Figure 4-2. Methodology for Measuring Electrical Resistance of the Jumper