SMT: Glossary Of Terms - Pqr Stage
Glossary of terms
Pad
A portion of a conductive pattern usually, but not exclusively, used for the connection attachment, or both of components. Also called a "land".
Paste Flux
A flux formulated in the form of a paste for special application, not to be confused with solder paste or solder-paste flux.
PCA or PWA, Printed Circuit or Wiring Assembly
A PCB containing attached components and interconnecting traces.
Pitting
The presence of pin holes or small craters in the solder joint caused by oxidation plating material or other foreign incompatible matter. Such joints are generally also dull in finish.
PLCC, Plastic Leaded Chip Carrier
A component package that has J-leads on four sides with standard spacing between leads.
Preheating
The process of raising board temperature to a level just below that of solder reflow to reduce overall thermal shock.
Primary Side
The side of the packaging and interconnecting structure equivalent to layer #1. This is commonly referred to as the component side in through-hole technology. In SMT, the primary side is reflow soldered.
Print Head
The Assembly in the printer that houses and controls the squeegee blade(s)
Printed Circuit Board (PCB)/ Printed Wiring Board (PWB)
The generic term for completely processed printed circuit configurations. It includes rigid or flexible single, double, or multilayer boards. A substrate of epoxy glass , clad metal, or other material upon which a pattern of conductive traces is formed to interconnect components.
Printed Wiring Assembly (PWA)
A printed wiring board on which separately manufactured components and parts have been added. The generic term for a printed wiring board after all electronic components have been completely attached. Also called “ Printed circuit Assemblyâ€.
PTH, Plated Through Hole
A plated via used as an interconnection between top and bottom sides or inner layers of PWB. Intended for mounting component leads into through-hole technology.
Quadpack
Generic term for SMT packages with leads on all four sides. Most commonly used to describe packages with gull wing leads. Also known as flat pack, but flat pack may have gull wing leads on either two or four sides.
Reflow Soldering
A process of joining metallic surfaces (without the melting of base metals) through the mass heating of preplaced solder paste to solder fillets in the metallized areas.
Repair
Restoring the functional capability of a defective PCB, which may or may not affect appearance interchangeability and/or uniformity.
Resist
Coating material used to mask or protect selected areas of pattern from the action of an etchant, solder or plating.
Rework
The process of bringing a defective assembly into conformance with required level of quality and is done for the purpose of improving the yield of acceptable parts. This often include operations like desoldering, soldering , and /or cleaning.
Rheology
The study of the flow properties of viscous materials.
