Electronic Assembly & Manufacturing Processes Flashcards

Which soldering defect is characterized by solder forming a bridge between two adjacent pads without wetting properly?

Answer: Solder bridging

Solder bridging occurs when excess solder connects two adjacent pads or leads, creating an unintended electrical short.

What is the primary purpose of nitrogen atmosphere in a reflow oven?

Answer: Reduce oxidation of solder and pads

Nitrogen atmosphere displaces oxygen, preventing oxidation of molten solder and PCB pads during reflow soldering.

In through-hole technology, what process is used to fill plated through-holes with solder from the bottom side of a PCB?

Answer: Wave soldering

Wave soldering passes the bottom of the PCB over a wave of molten solder to simultaneously solder all through-hole leads.

Which component placement defect occurs when a chip component stands on one end due to uneven solder paste wetting?

Answer: Tombstoning

Tombstoning (also called drawbridging) happens when one end of a component lifts up due to unbalanced surface tension forces during reflow.

What is the recommended approach when reworking a BGA component according to IPC standards?

Answer: Use approved rework station with profiled heat

BGA rework requires a specialized rework station that applies profiled heat to reflow solder balls without damaging adjacent components.

Which IPC standard specifically addresses the acceptability of electronic assemblies?

Answer: IPC-A-610

IPC-A-610, Acceptability of Electronic Assemblies, is the most widely used electronics assembly standard defining workmanship criteria.

What does the term 'tombstoning' describe in SMT assembly?

Answer: A component lifted vertically on one end

Tombstoning is an SMT defect where one end of a chip component lifts off the pad during reflow due to unequal surface tension forces.