BGA package technology considerations for high speed and RF applications

Ball Grid Array packaging for integrated circuits permits to address most standard electronics applications with recognized and proven advantages of low cost, high volume capability, design flexibility & electrical/thermal/mechanical performances. However, standard BGA package technology approach, i.e. cost driven technology selection in other words, is reaching some limits for latest and future high speed and RF applications. In addition to the evolution of package design rules (enabling higher density and integration capabilities) and the evolution of assembly processes (such as the transition from die wire bonding to flip chip connection), some other issues must be considered to address these applications running at very high data rates and / or high working frequencies. Amongst these considerations, the key points to target package performances fitting with the product specifications are linked to the technology choices, especially for the materials of the laminate substrate of the package. For standard BGA materials there is currently a lack of electrical properties data at very high frequencies that may be problematic to determine package electrical behavior. In addition, current tolerances of substrate manufacturing may impact drastically overall performances whereas they were not so harmful for previous product generations running at slower frequencies. Impact of the material electrical properties and manufacturing tolerances will be demonstrated thru concrete examples and simulation results. The actions to lead with substrate manufacturers and material providers to manage successfully these high speed and RF signals constraints faced by the BGA IC packaging and to anticipate the coming ones will also be discussed.