Cost effective, mass productive Wafer-Level Chip Size Package (WLCSP) technology applied to Ku-band frequency converters

Cost effective, mass productive Ku-band up- and down-converter MMIC's for wireless communication are presented. These MMIC's are designed by using a three-dimensional MMIC technology that optimized for flip-chip solder reflow-compatible implementation; hence, that removes necessity of packaging. The MMIC structure incorporates inverse TFMS lines so that a ground metal can be applied to cover the whole chip surface except for interconnect pads. Among multi-polyimide and SiN layers, four wiring metal layers are composed. The up-converter MMIC's were composed of a pair of balanced mixers, which are doubly balanced with additional quadrature couplers and a LO amplifier. The down-converter is composed of an image-rejection mixer, a LO amplifier and low-noise amplifier. The components are effectively integrated in a 2.4mm × 2.4mm die. An up-converter exhibited a Gc of -12dB, an IIP3 of nearly 20dBm, and a LO-to-RF leakage of less than -35dBm for a 0dBm of LO input. A 13-15GHz down-converter exhibited a Gc of +12dB, an IIP3 of better than 0dBm, and an image-rejection ratio of greater than 20dB (>;30dB for flip-chip assembly) for a 2dBm of LO input. The measurements were performed in both the face-up (with RF-Probe) and flip-chip fashions. An LTCC package implementation was also examined. As a result, the RF performances did not depend on these measurement states and showed high repeatability. We also present the mass productivity of WLCSP MMIC by showing statistical data.