A computer program that generates an RF electrical model of the parasitics of QFP packages

The Package Parasitic Model Program is a computer program, that can generate an RF model of the electrical parasitics for quad flat pack IC packages. The program, written in C, constructs the proposed package layout by employing user entered dimensions to generate approximate lengths and positions of the package's internal routing. It then determines the parasitics for a package layout by solving equations that compute its resistance, inductance and capacitance. A 64 Thin Quad Flat Pack was used (employed in most cellular phones) as a test vehicle to verify the program's capability of generating an accurate RF model. 50 ohm resistors were conductive epoxied to the lead frame die paddle and wire bonded to various leads. The lead frames were then molded into packages, X-rayed and tested. A series of calibration and test fixtures was designed so that the packages could be measured by an HP-8510 Network Analyzer. Electrical models of the sample packages were generated by the program and Celerity simulations to 6 GHz were performed on the package models. Agreement between measurements and simulations was observed, across 4 GHz of bandwidth, to be within 1 dB for return loss and 2 dB for crosstalk.