In this study, we introduce an innovative methodology for the design of mm-Wave passive networks that leverages knowledge transfer from a pre-trained synthesis neural network (NN) model in one technology node and achieves swift and reliable design adaptation across different integrated circuit (IC) technologies, operating frequencies, and metal options. We prove this concept through simulation-based demonstrations focusing on the training and comparison of the coefficient of determination (R2) of synthesis NNs for 1:1 on-chip transformers in GlobalFoundries(GF) 22nm FDX+ (target domain), with and without transfer learning from a model trained in GF 45nm SOI (source domain). In the experiments, we explore varying target data densities of 0.5%, 1%, 5%, and 100% with a complete dataset of 0.33 million in GF 22FDX+, and for comparative analysis, apply source data densities of 25%, 50%, 75%, and 100% with a complete dataset of 2.5 million in GF 45SOI. With the source data only at 30GHz, the experiments span target data from two metal options in GF 22FDX+ at frequencies of 30 and 39 GHz. The results prove that the transfer learning with the source domain knowledge (GF 45SOI) can both accelerate the training process in the target domain (GF 22FDX+) and improve the R2 values compared to models without knowledge transfer. Furthermore, it is observed that a model trained with just 5% of target data and augmented by transfer learning achieves R2 values superior to a model trained with 20% of the data without transfer, validating the advantage seen from 1% to 5% data density. This demonstrates a notable reduction of 4X in the necessary dataset size highlighting the efficacy of utilizing transfer learning to mm-Wave passive network design. The PyTorch learning and testing code is publicly available at https://github.com/ChenhaoChu/RFIC-TL.