annular ring


Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.
Related to annular ring: annulus

annular ring

n.
An opaque area appearing in radiographs of the lung and indicating a cavity of tuberculosis. Also called pleural ring.
References in periodicals archive ?
As copper is washed off the PCB, traces and annular rings become thinner or nonexistent.
The IPC the acceptance standards call for vertical microsec-tions of coupons on PCBs, which do not allow measurement of breakout in internal annular ring.
Usually, there is an annular ring requirement or a spec that at least demands tangency.
Rapid dissolution of copper into tin-rich alloys can create hidden defects and reliability issues, and as copper is washed off the PCB, the exposed traces, annular rings and barrel knees can become thinner or even nonexistent.
Since you cannot have one photo-tool for each individual panel, the next best solution is to use the minimal number of photo-tools for the solder mask process, and still keep the design specification on the annular ring.
For a panel that requires an annular ring of 50 or 75 pm, most of the design tolerance might be exhausted from a single production step.
Finding mask-to-trace problems in your CAD system is difficult, because few (if any) CAD systems offer more than a basic annular ring check when it comes to soldermask data.
By calculating the via hole plane clearance size, the minimum copper-to-hole annular ring can be determined, and this value is derived by the PCB manufacturer.