Dog bone
Dog bone turns up in 2 fields: adhesives, PCBs. Here is what it means to the people in each one.
Dog bone in adhesives
A cast or cut tensile specimen with wide ends and a narrow middle, used to test bulk adhesive properties.
Cured adhesive is molded or cut into the familiar dumbbell shape so the narrow gauge section breaks in tension. Pull tests on dog bones give tensile strength, modulus and elongation of the adhesive itself, free of any interface. They help compare formulations and feed numbers into joint design calculations.
"Pour a sheet and cut five dog bones, I need the modulus before we model the joint."
Dog bone in PCBs
Short trace from a surface mount pad to a nearby via, shaped like a cartoon bone, used to fan out parts.
A dog bone is the classic fanout pattern of a pad, a short neck of trace and a via, which together look like a bone. Under a BGA, each ball pad gets a dog bone to a via placed in the gap between four pads, so signals can drop to inner layers without putting holes in the pads. It works comfortably at 0.8 mm pitch and above, gets tight at 0.65 and 0.5 mm, and at finer pitches via-in-pad usually takes over.
"0.8 mm pitch fits dog bones with 0.2 mm vias, no need to pay for via-in-pad on this one."