Acceptability of Electronic Assemblies Flashcards

For a chip component (0402) on a Class 2 assembly, the maximum side overhang allowable relative to the land is:

Answer: 50% of component width

IPC-A-610 allows up to 50% side overhang for chip components on Class 2 assemblies before it becomes a defect.

What is the IPC-A-610 term for a solder joint condition where solder has not wetted the component termination or land surface?

Answer: Nonwetting

Nonwetting occurs when solder fails to wet and adhere to the base metal surface at all.

A gull-wing lead's toe extends beyond the land end on a Class 2 assembly. Per IPC-A-610, this is:

Answer: Acceptable if the solder joint criteria are met

Toe overhang on gull-wing leads is acceptable for Class 2 provided the solder joint meets all other criteria.

According to IPC-A-610, 'lifted lands' or pad liftoff is classified as:

Answer: A defect for all classes

Lifted lands/pad liftoff is a defect condition for all classes per IPC-A-610.

For BGA components, IPC-A-610 inspection of solder joints typically relies primarily on:

Answer: X-ray inspection or automated optical inspection

BGA joints are hidden under the package and require X-ray or AOI for inspection per IPC-A-610 guidance.

A solder ball found on the surface of a PCB assembly (not attached to a joint) is classified per IPC-A-610 as:

Answer: A defect if it can cause a short circuit

Solder balls that can cause electrical shorts or detach and create shorts are defects per IPC-A-610.

Which SMT solder joint feature is described as solder that has pulled away from the land after initially wetting, leaving a thin film?

Answer: Dewetting

Dewetting is when molten solder initially wets but then recedes, leaving an irregular, thinly coated surface.