CIS Electronic Assembly & Manufacturing Processes 2

Question 1

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

Accepted Answer

Solder bridging

Answer

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

Question 2

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

Accepted Answer

Reduce oxidation of solder and pads

Answer

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

Question 3

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

Accepted Answer

Wave soldering

Answer

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

Question 4

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

Accepted Answer

Tombstoning

Answer

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

Question 5

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

Accepted Answer

Use approved rework station with profiled heat

Answer

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

(CIS) Certified IPC Specialist Practice Test