The practical difference
MBB and SMBB describe increasingly dense interconnection layouts. More conductors can shorten current paths and reduce the current carried by each ribbon, but the design also tightens requirements around diameter consistency, handling and equipment alignment.
Diameter is a system variable
A smaller diameter can reduce shading and adapt to dense layouts, while electrical resistance, feeding stability and joint area still need to remain inside the module program's acceptance window.
- Electrical loss and shading balance
- Stringer tooling and feeding behavior
- Cell stress and mechanical handling
- Wetting area and peel-force target
Mechanical data needs context
Tensile strength and elongation are not independent marketing numbers. They influence spool handling, straightness, deformation, cell loading and the consistency of the finished string. Qualification should define both the target and the measurement method.
Build a line-trial matrix
Compare a bounded set of diameters and mechanical windows under controlled flux, temperature and speed. A small, documented trial matrix usually produces a better answer than testing many unrelated ribbon variants.