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Glossary

Imp e d a nc e P a d
The measurement in ohms of the apparent resistance of an ACcircuit. Impedance depends on several factors: DC resistance, capacitance, inductance of the line, the width of the conductor strands, and the conductor spacing relative to ground and insu- lating layers. The portion of a conductor, usually surrounding a through-hole,that is used to connect a component for an electrical connec- tion. Pads are sometimes referred to as “terminals”or “lands.” M a jor a cc ess ho le
Pad An access hole (see “Access hole”) that is large enough toexpose a major portion of a conductor pad, which is usually coated with solder. Major Access Ho l e Profi le to le r a nc e
Dimensional tolerancing where the part trim line is containedwithin a tolerance zone consisting of the area between two par- allel lines, separated by the specified tolerance. For example, a circuit to be trimmed with a steel rule die might have a toler- ance of 0.015" (0.38mm) (A 0.030"/0.76mm wide profile toler- ance zone). The circuit trim line could vary anywhere inside the zone. Minor a cc ess ho le
An access hole (see “Access hole”) that exposes only a very smallportion of a conductor pad, used on holes where a solder pad is not needed or desired. The cover hole must still be larger than the through-hole to allow for normal registration tolerances. .030" (0.76mm)AB B Minor Access Ho l e A DRAWING CALLOU T NOMINAL T RIM LINE N es tin g
Designing circuits so that they lay closely together on a panelduring production. This maximizes the usage of panel space, which minimizes production cost. .030" (0.76mm) WIDE T OLERANCE Z ONE EXAMPLE Punch- a nd-di e
Hard-tooling that is used in a punch press. A punch-and-dieconsists of two precisely matched metal plates held in special die shoes. When the punch press is activated, the plates come together in order to punch a specific pattern into material. 29