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Agilent AN 1300-5 Electronic Characterization of IC Packages Application Note Agilent 4291B RF Impedance/Material Analyzer 1. Overview The leading implication is that the 3. The IC Package This application note describes in impedance characteristics of the IC packages can vary in size, topology, broad terms how to use the Agilent IC package leads will dramatically number of pins, substrate material, Technologies 4291B RF Impedance/ contribute to reflections, overshoot, geometry, and lead length. Each has its Material Analyzer in determining the undershoot, and crosstalk distortions own strengths and limitations. Within impedance characteristics of IC pack- of the signal. This situation is com- all IC packages are lead frames, the ages up to 1.8 GHz. This information is pounded by the rapidly shrinking conductors that connect the internal useful for high speed digital designers, physical size of the IC packages leads, IC to a pc board. The lead frame is component evaluation engineers, RF the processing of low level signals, imbedded on a rigid structure that design engineers, IC package users in and the ever increasing pin density. becomes the IC package. the analog or digital design environ- ment, and for IC package manufac- turers. This measurement solution will accurately measure the imped- ance, inductance, and capacitance characteristics of IC package conduc- tors and leads. 2. Packaging Affects Performance The frequencies that ICs operate at are growing higher. In computer systems, clocks that now operate at 100 MHz will increase to 1 GHz by the year 2000. Refer to Figure 2-1, Digital Rate Trends. When chips run at high frequencies (above 50 MHz) and the signal edges consist of frequency components that are much higher, the lead conductors of IC packages that link the chips to the circuit boards start behaving like transmission lines. The conductor will have inductance, capacitance, and resistive elements. Figure 2-1. Digital rate trends The lead frames are usually made up Self inductance (Lxx) A typical value can be up to hundreds of copper alloy and have fine traces This is the number of magnetic field of milliohms, depending upon the with different lengths and dimensions. lines around a single conductor (lead) type of lead material, lead length, and These traces can have ends that ter- per amp of current flowing through surface area. minate near the IC with a width of it. Typical values for a lead can range 0.10 mm. The intrinsic properties from 2 to 20 nH, depending upon the Interlead Capacitance (Cxo) of the IC conductive and insulative length of the conductor and the phys- Lead capacitance is the amount elements