CIS CIS Acceptability Criteria & Defect Recognition 2

Question 1

What is 'tombstoning' in the context of SMT assembly?

Accepted Answer

A defect where one end of a chip component lifts off its pad during reflow

Answer

A type of solder bridge between adjacent pads

Answer

Excessive solder forming a columnar shape on a pad

Answer

A component placed at 90° to its intended orientation

Question 2

According to IPC-A-610, component skew for chip resistors and capacitors is acceptable for Class 2 when:

Accepted Answer

Both terminations remain on their respective pads within specified limits

Answer

The component is rotated no more than 45°

Answer

The component does not touch adjacent components

Answer

No skew is acceptable for Class 2

Question 3

What defect is described as solder that forms a sharp peak or spike projecting from a solder joint?

Accepted Answer

Solder icicle (solder spike)

Answer

Solder balling

Answer

Solder skip

Answer

Webbing

Question 4

For IPC-A-610, what is the acceptability status of a solder ball that is NOT entrapped under a component and can be removed without damaging the assembly?

Accepted Answer

Process indicator for Class 1, defect for Class 2 and 3

Answer

Always acceptable for all classes

Answer

Defect for Class 3 only

Answer

Defect for Class 2 and Class 3

Question 5

'Dewetting' in soldering refers to:

Accepted Answer

Solder that wetted a surface but then partially pulled back, leaving an uneven, irregular surface

Answer

Solder that has not melted sufficiently during the soldering process

Answer

A base metal surface that has been oxidized prior to soldering

Answer

The process of removing flux residue after soldering

Question 6

According to IPC-A-610, which condition constitutes a defect for all classes regarding component body damage?

Accepted Answer

Cracking that exposes internal component material

Answer

Minor surface scratches on the component body

Answer

Discoloration of the component body from heat

Answer

Damaged component markings that are still partially readable