IPC A 610 CORE REVIEWS ANSWERS AND
QUESTIONS SET A+
✔✔Probe mark vs fracture? - ✔✔A probe mark can deform the surface without creating
an actual crack.
✔✔What is an inclusion? - ✔✔Foreign material incorporated into or associated with a
solder connection.
✔✔Does the existence of an inclusion automatically make every joint defective? -
✔✔No; the applicable criterion controls.
✔✔What is THT? - ✔✔Through-Hole Technology.
✔✔What is PTH? - ✔✔Plated-Through Hole.
✔✔What is a supported hole? - ✔✔A hole whose plated conductive structure provides
the intended electrical interconnection/support.
✔✔What is an unsupported hole? - ✔✔A hole without the plated-barrel interconnection
of a supported PTH.
✔✔What is the PTH barrel? - ✔✔The conductive plating on the interior wall of a plated-
through hole.
✔✔What is vertical solder fill? - ✔✔The extent of solder filling the plated barrel through
the board thickness.
✔✔What is a clinched lead? - ✔✔A through-hole lead intentionally bent after insertion
for mechanical retention.
✔✔What is lead protrusion? - ✔✔The amount a through-hole lead extends beyond the
board/connection.
, ✔✔Why can excessive lead protrusion matter? - ✔✔It can cause clearance or
interference problems.
✔✔Why can too little protrusion matter? - ✔✔It may fail the applicable
connection/protrusion requirement.
✔✔Why is lead bend radius important? - ✔✔A bend that is too sharp can damage or
overstress the lead.
✔✔Why should a bend not be made too close to a component seal or body? - ✔✔It can
transfer mechanical stress into the component package or seal.
✔✔What is an axial-leaded component? - ✔✔A component with leads extending from
opposite ends.
✔✔What is a radial-leaded component? - ✔✔A component with leads emerging
generally from the same side/body region.
✔✔What is hole obstruction? - ✔✔A condition interfering with the intended through-hole
opening, connection, soldering, or inspection access.
✔✔What is meniscus in solder? - ✔✔The component's body-side meniscus/seal region
extends into the soldered connection area.
✔✔Why can lead cutting after soldering be significant? - ✔✔The mechanical cutting
force can damage the completed solder connection, land, or lead interface.
✔✔What is SMT? - ✔✔Surface Mount Technology.
✔✔What is side overhang? - ✔✔Lateral extension of a component termination beyond
the side edge of its land.
✔✔What is end/toe overhang? - ✔✔Extension of a termination beyond the end/toe edge
of its land.
✔✔What is end joint width? - ✔✔The width of the soldered connection at the
termination end.
✔✔What is side joint length? - ✔✔The overlap/connection length along the side of the
termination and land.
✔✔What is solder thickness? - ✔✔The thickness of solder between the termination and
land.
QUESTIONS SET A+
✔✔Probe mark vs fracture? - ✔✔A probe mark can deform the surface without creating
an actual crack.
✔✔What is an inclusion? - ✔✔Foreign material incorporated into or associated with a
solder connection.
✔✔Does the existence of an inclusion automatically make every joint defective? -
✔✔No; the applicable criterion controls.
✔✔What is THT? - ✔✔Through-Hole Technology.
✔✔What is PTH? - ✔✔Plated-Through Hole.
✔✔What is a supported hole? - ✔✔A hole whose plated conductive structure provides
the intended electrical interconnection/support.
✔✔What is an unsupported hole? - ✔✔A hole without the plated-barrel interconnection
of a supported PTH.
✔✔What is the PTH barrel? - ✔✔The conductive plating on the interior wall of a plated-
through hole.
✔✔What is vertical solder fill? - ✔✔The extent of solder filling the plated barrel through
the board thickness.
✔✔What is a clinched lead? - ✔✔A through-hole lead intentionally bent after insertion
for mechanical retention.
✔✔What is lead protrusion? - ✔✔The amount a through-hole lead extends beyond the
board/connection.
, ✔✔Why can excessive lead protrusion matter? - ✔✔It can cause clearance or
interference problems.
✔✔Why can too little protrusion matter? - ✔✔It may fail the applicable
connection/protrusion requirement.
✔✔Why is lead bend radius important? - ✔✔A bend that is too sharp can damage or
overstress the lead.
✔✔Why should a bend not be made too close to a component seal or body? - ✔✔It can
transfer mechanical stress into the component package or seal.
✔✔What is an axial-leaded component? - ✔✔A component with leads extending from
opposite ends.
✔✔What is a radial-leaded component? - ✔✔A component with leads emerging
generally from the same side/body region.
✔✔What is hole obstruction? - ✔✔A condition interfering with the intended through-hole
opening, connection, soldering, or inspection access.
✔✔What is meniscus in solder? - ✔✔The component's body-side meniscus/seal region
extends into the soldered connection area.
✔✔Why can lead cutting after soldering be significant? - ✔✔The mechanical cutting
force can damage the completed solder connection, land, or lead interface.
✔✔What is SMT? - ✔✔Surface Mount Technology.
✔✔What is side overhang? - ✔✔Lateral extension of a component termination beyond
the side edge of its land.
✔✔What is end/toe overhang? - ✔✔Extension of a termination beyond the end/toe edge
of its land.
✔✔What is end joint width? - ✔✔The width of the soldered connection at the
termination end.
✔✔What is side joint length? - ✔✔The overlap/connection length along the side of the
termination and land.
✔✔What is solder thickness? - ✔✔The thickness of solder between the termination and
land.
