Paste Flux

A flux formulated in the form of a paste. Flux may also be in fluid form.

PCA or PWA, Printed Circuit or Wiring Assembly

A PCB containing attached components and interconnecting traces.

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 Assembly”.

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. This is usually done soon after soldering. This often include operations like desoldering, soldering , and cleaning.

Rheology

The study of the flow properties of viscous materials.