APDS modified several bisphenol A polyimides with low dielectric constant under high frequency

In the area of Polymer dielectric materials, those with low dielectric constant and low dielectric loss have potential to be applied in high-frequency signal transmissions, such as antennae of mobile phones and millimeter-wave radars. This study is focused on producing fluorinated polyimide (PI) film with modified organosilicon (APDS). In this work, APDS was used to PI film. The spatial hindrance of Trifluoromethyl can reduce the high frequency dielectric loss of modified PI film. The length of molecular chain was decreased as increasing the proportion of APDS, which reduced the quantity of polar imide rings in unit volume. Meanwhile, the Si-O-Si bond combination in backbone decreased the integer polarity of PI film, which resulted in the decrease of tan 𝛿�. The values of epsilon and tan 𝛿� were 2.48 and 0.00335 respectively under 10 GHz. The values of epsilon and tan 𝛿� were reduced to 6.6% and 36.5% respectively compared with base membrane. Thus, this work provides a simple method to reduce the dielectric constant and dielectric loss of PI film. Meanwhile, the relationship between dielectric properties and molecular structure was proved. PI molecules were separated by low dielectric groups, which resulted in a decrease in dielectric constant and dielectric loss.