Bond pads for fine-pitch applications on air bridge circuit boards

摘要

An etched tri-metal-layer air bridge circuit board specially designed for fine-pitch applications, comprising:an electrically insulative substrate surface (10), a plurality of tri-metal-layer bond pads (12) arranged in a generally straight row on the substrate surface (10) wherein the row defines a width direction therealong, and a circuit trace (20) arranged on the substrate surface (10), wherein the circuit trace (20) runs between two adjacent ones (22) of the plurality of tri-metal-layer bond pads (12). Each bond pad (12) comprises: (1) a bottom layer (14) attached to the substrate surface (10), the bottom layer (14) being made of a first metal and having an overall width W1 as measured along the width direction; (2) a top layer (18) disposed above and generally concentric with the bottom layer (14), the top layer (18) being made of the first metal and having an overall width W2 as measured along the width direction; and (3) a middle layer (16) made of a second metal connecting the bottom layer (14) and the top layer (18). The bond pads (12) are specially shaped such that W2 W1 for at least the two adjacent bond pads (12), thus enabling the circuit trace (20) to be spaced closely to the bottom layers (14) of the two adjacent bond pads (12), while allowing the top layers (18) of the pads (12) to be made much larger so as to avoid delamination thereof from their associated middle layers (16).