No Visual Fault Analysis (NVFA) for Inoperative RF Power Amplifier: A Systematic Approach

In today´s rapidly RF customer demands, power amplifiers (PA) are required to operate over a multiple range of frequency bands. Philips Semiconductors introduces its triple band RF PA modules to operate on GSM systems on three frequency bands: EGSM900 (880 to 915 MHz), DCS1800 (1710 to 1785 MHz) and PCS1900 (1850 to 1910 MHz). This drives PA´s to accommodate applications not only as multiband but also as wideband amplifiers. Dealing with this kind of PA technology means a comprehensive know how on the module especially when electrical failure occurs. Considering multilayer LTCC substrates, passive integration dies and other miniaturized materials; failure analysis (FA) plays a very important role during the PA introduction. FA during product development and until mass production is the detective process of determining the why and how PA modules fail. This paper is intended to established a laboratory procedure on how no visual fault are being analyzed specifically for Inoperative RF PA module after final test. The study was based on no visual fault failures encountered after final test on a triple band RF PA during its introduction phase.