Methods and apparatus for packaging a backside illuminated (BSI) image sensor or a sensor device with an application specific integrated circuit (ASIC) are disclosed. According to an embodiment, a sensor device may be bonded together face-to-face with an ASIC without using a carrier wafer, where corresponding bond pads of the sensor are aligned with bond pads of the ASIC and bonded together, in a one-to-one fashion. A column of pixels of the sensor may share a bond bad connected by a shared inter-metal line. The bond pads may be of different sizes and configured in different rows to be disjoint from each other. Additional dummy pads may be added to increase the bonding between the sensor and the ASIC.