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Electrical Requirements
R
20 mPGA604 Socket Design Guidelines
4.1 Electrical Resistance
Figure 4-1 and 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 R
Total
. The resistance requirement, R
Req
, can be calculated for each chain as
will be explained later.
Figure 4-1. Methodology for Measuring Total Electrical Resistance
Interposer Shoulder
Interposer Pin
Motherboard
Socket Contact
Interposer
Shorting Bar
+V
+I
-V
-I
Figure 4-2. Methodology for Measuring Electrical Resistance of the Jumper
Inter
p
oser Shoulder
Motherboard
Interposer
Shorting Bar
+V
+I
-V
-I
Figure 4-3 shows the resistance test fixtures separately and superimposed. The upper figure is the
package. The next figure is the baseboard. There are 48 daisy chain configurations on resistance test
board. The bottom figure is the two parts superimposed. Table 4-3 shows these configurations with
the number of pins per each chain and netlist.