Electrical Requirements

R

4.2Determination of Maximum Electrical Resistance

This section provides a guideline for the instruments used to take the measurements.

Note: The instrument selection should consider the guidelines in EIA 364-23A.

1.These measurements use a 4-wire technique, where the instruments provide two separate circuits. One is a precision current source to deliver the test current. The other is a precision voltmeter circuit to measure the voltage drop between the desired points.

2.These separate circuits can be contained within one instrument, such as a high quality micro- ohmmeter, a stand-alone current source and voltmeter, or the circuits of a data acquisition system.

3. Measurement accuracy in Ω is specified as ± 0.1% of reading, or ± 0.1 m Ω , whichever is greater. The vendor is responsible for demonstrating that their instrument(s) can meet this accuracy.

4.Automation of the measurements can be implemented by scanning the chains through the edge or cable test connector using a switch matrix. The matrix can be operated by hand, or through software.

5.Measure RTotal for each daisy chain of “package + socket + motherboard” unit.

6.Measure Rjumper for each daisy chain of 30 “package + motherboard” units. Calculate

R jumper for each daisy chain (There is 30 data for each daisy chain).

7.For each socket unit, calculate

R Req =

R Total −

R

jumper

N

 

RReq is the average contact resistance for socket pin.

4.3Inductance

The bottom fixture for the inductance measurement is a ground plane on the secondary side of the motherboard with all pins grounded. The component side of the socket PCB does not contain a plane. The top fixture is the package, which contains pins that will connect to the socket. Figure 4-4shows the inductance measurement fixture cross-section and the inductance measurement methodology. The first figure shows the entire assembly. The second figure shows the assembly without the socket; the socket-seating plane of the package is directly mounted to the component side of the socket PCB. This is used to calibrate out the fixture contribution. The materials for the fixture must match the materials used in the processor. Note the probe pad features exist on the topside of the top fixture, and the shorting plane exists only on the bottom side of the bottom fixture. Figure 4-5presents the inductance and capacitance fixture design.

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mPGA604 Socket Design Guidelines