X-Ray Inspection-Induced Latent Damage in DRAM

For quality verification, an X-ray inspection process is commonly being used for evaluating obscured and defective solder joints in surface mount technologies such as BGA´s and flip chips. Integrated circuits subjected to any form of radiation, ionizing or non-ionizing, may incur some amount of damage depending on the absorbed dose. Though most X-ray inspections for high-quality imaging require ionizing dose amounts that are considered inconsequential for device failure or non-functionality, the degree of latent damage must be carefully considered. This paper discusses X-ray induced vulnerabilities of high-density DRAM exposed to low ionizing radiation levels typical in X-ray inspection systems. We look at critical parameters and their sensitivity in relation to varying dose amounts of X-ray irradiation. In consideration of different methodologies of reducing radiation dose amounts and limiting device exposure, we propose a procedure for attenuating potentially harmful X-ray radiation levels while preserving quality images