Solder Deposition
Precision manufacturing processes attach electronic components directly onto the copper pads of a printed circuit board. This method, surface mount assembly, has replaced older through-hole techniques to increase component density on the board. Automated production lines execute these steps to achieve high throughput and repeatable electrical connections.
Component Placement
Stencil printing applies a precise volume of solder paste to each component footprint before component placement. During surface mount assembly, the alignment of the stencil to the circuit board must remain within narrow tolerances. If the solder paste volume is incorrect, it can lead to electrical opens or short circuits.
Automated solder paste inspection machines scan each board to verify the deposit height and area.
Reflow Profile
High-speed pick and place machines position each component onto the deposited paste with micron-level accuracy. The surface mount assembly relies on the tackiness of the solder paste to keep the parts in position before reflow soldering. Mechanical feeders supply the components from plastic tapes to the placement head.
These automated systems check the dimensions of the component to verify that the correct package is being placed.
Joint Inspection
Conveyorized ovens heat the assembled boards to melt the solder alloy and form durable metallurgical joints. In surface mount assembly, the thermal profile must be carefully controlled to prevent component damage and poor solder wetting. This profile includes specific ramp rates and a peak temperature held for a limited duration.
Technicians profile the oven using a test board to certify that the thermal zones match the paste specifications, measuring the internal temperature at multiple board locations during the heating cycle.
