Real-Time Detection of Solder-Joint Faults in Operational Field Programmable Gate Arrays

In this paper we present two sensors for real-time detection of solder-joint faults in programmed, operational field programmable gate arrays (FPGAs), especially those FPGAs in ball grid array (BGA) packages. The first sensor uses a method in-situ within the FPGA and the second sensor uses a method external to the FPGA. Initial testing indicates the first method is capable of detecting high-resistance faults of 100 Omega or lower and which last one-half a clock period or longer. A prototype of the second method detected high-resistance faults of at least 150 Omega that lasted as low as 25 ns.