Insertion loss is recommended to be better than –1.5 dB from the BGA ball to its balun (or similar interfacing component). Most board materials are capable of achieving better than –1.5 dB of insertion loss at frequencies up to around 6 GHz. Insertion loss mitigation does come with a potentially significant cost multiplier, so care should be taken in choosing the proper material. See Material Properties and Insertion Losses for insertion loss values based on trace widths and frequencies.