Study of the Effect of No-Clean Flux Residue on Signal Integrity at High Frequency

The majority of electronic products today are built using no-clean soldering processes. However, the effect of no-clean flux residue on signal integrity is a concern for many high-frequency products, such as fifth-generation (5G) and other communication products. No-clean flux residue can create an alternative path to the signal and degrade the signal integrity performance, especially at high frequency. However, there are limited studies on the effect of no-clean residue on signal integrity. This work sets out to study the effects of no-clean flux residue on signal integrity at high frequency, including the frequency spectrum used for 5G technology. This study includes the analytical modeling of the dielectric loss and impedance mismatch loss at high frequency. In addition, the insertion loss is measured at different frequencies up to 50 GHz. The results show that the loss due to the presence of no-clean flux residue is statistically insignificant within the scope of this study.