HVAC inverter boards often need to cross components and heat sinks in a limited height. Three-dimensional SMT jumpers can replace part of a harness or hand-formed strip, but their pads, springback and thermal stress must be defined with the PCB.
Define the jumper function first
Some jumpers only carry DC power; others also connect a fast-switching node. The first group is driven by section and cooling. The second also needs loop-area, coupling and parasitic-inductance control. Separate these requirements before choosing material and thickness.
Control forming and the reflow window
Draw the datum, bend sequence, inside radius, springback compensation and no-mark zones. Pads must account for copper mass, paste outgassing, visible fillets and rework access. State the soldering and non-soldering finish boundaries.
- Check flatness, coplanarity and mounted height
- Use cross-sections or X-ray sampling after reflow
- Repeat voltage-drop and crack checks after thermal cycling
Give EMS and the metal supplier one input set
The RFQ should include PCB land pattern, placement direction, reflow profile, annual volume and packaging. A DFM review should cover nozzle interference, stencil apertures, support tooling and transit deformation before tooling is released.