| EMS Glossary A | B | C |
D | E | F | G
| H | I | J | K | L
| M | N | O | P
| Q | R | S | T
| U | V | W | X | Y | Z
A Air Knives A device that uses pressurized air to dry panels during the fabrication process, e. g. drying a printed circuit board after the stripping process. Air Oxidation Oxidation resulting when panels are exposed to ambient conditions. Also see Oxidation. Ammoniacal Etchant Also known as Alkaline Etchant - An etchant that uses ammonia to complex copper ions thereby retaining copper in a non-metallic chemical solution. C Chrome/Sulfuric Formulations A material made of chromic acid and sulfuric acid that was used as an early form of etchant solution chemistry. Chloride A molecule or compound that contains a chloride atom. Chloride ions increase etch rates in etching solutions. Conical Spray Nozzle A spray nozzle configuration that produces a cone-shaped spray. (See also Spray Nozzle). Complex A strong chemical bond also known as a Chelate. Conductor The copper circuitry on the printed circuit board. Controller A proprietary component to the alkaline etching system used to control copper concentration based on baume or specific gravity. The controller activates a pump that automatically adds replenisher at the prescribed copper concentration and removes spent etchant. Conveyor A series of parallel mechanically driven bars that transport the panels through the etching process as well as other processes. Conveyor Rate The measurement of the speed at which the board passes through a spray etcher. One variable used to determine undercut and level of resist attack. Conveyor Speed Breakpoint A measurement of the distance through the etching chamber at which the copper is fully etched from the printed circuit board. Copper Capacity A measurement of the total copper that an etchant can solubolize without loss of a specified etch rate. Cupric Ion Copper ion its divalent state. Symbol: Cu+2. Cuprous Ion Copper ion in its monovalent state. Symbol: Cu+.  D
Damper A device within the exhaust vent that can restrict the air flow through the exhaust vent. D. E. S. "Develop the dry film, Etch the inner layer, Strip the dry film." D.E.S. is the conveyorized process that prepares an inner layer board for oxide coating. Developing A process that hardens and prepares an image on a printed circuit board. Once this process is finished, the PWB is ready for the next process step, either etching for inner layers or copper plating for outer layers. Developing Chamber A piece of conveyorized equipment where chemicals are used to harden and prepare an image on a board. Dry Film A sheet of polymer that is laminated onto a printed circuit board. It is used to create an image on a panel. E Etch Factor The ratio of the etch depth to the amount of undercut or lateral etch. Etching Chamber The front part of an etcher that is enclosed and that contains the sump, spray manifolds and spray nozzles. Etchant in the sump is pumped into the spray manifolds and released onto the panels through the spray nozzles. Etch Rate The speed at which copper is etched from the printed circuit board. Etch rate is influenced primarily by the type of etchant, spray pressure, pH, temperature and type of laminate. Etch Uniformity The consistency of the etch and etch factor along the entire printed circuit board. Exhaust Vent A line from an etcher where fumes (ammonia or acid) are removed out of the processing area and into a scrubbing device. F
Fan Shaped Spray Nozzles A spray nozzle configuration that produces a fan-shaped spray. (See also Spray Nozzle). Fan Spray Pattern Fan-shaped spray that results in a linear distribution of etchant on the panel. Ferric Chloride A compound used as an early form of etchant chemistry used today to chemically mill parts. Also used in water treatment applications. Fine Line Etching A method for etching with minimal undercut, generally results in slightly slower etch rates and involves etchants with lower chloride contents and lower pH to protect dry film. Finishing Solution Used as a post etching step to remove unwanted etchant residue and brighten solder, also known as Solder Brightener. Flood Rinse Module A unit that follows the Etching Chamber in etching equipment. It contains a series of cascading rinse chambers that concentrate fresh replenisher while rinsing panels leaving the Etching Chamber. Also abbreviated as "FRM". Fresh Etchant New or unused etching solution. Also known as Replenisher. Galvanic Cell Reaction The enhanced undercut resulting from the electrical interaction between the copper plate and a metallic resist. H High Speed Etchant Refers to etching solutions with higher etch rates, generally containing higher concentration of chlorides. They also tend to have greater copper capacity. Horizontal Etcher An etcher is which panels pass through the etching chamber and FRM horizontally. Spray nozzles and spray manifolds are situated on the top and the bottom of the conveyor. Hybrid Refers to a printed circuit board fabricated utilizing a combination of SMT and PTH. Hydrochloric Acid Inorganic acid used as one component of etchant in the cupric chloride etching process. Also known as Muriatic Acid. I
Impedance A measurement of resistance of electrical energy passed through a conductor circuit. Innerlayer Etching Etching of a printed circuit board that will be pressed into the interior of a multilayer printed circuit board. L Lateral Etching Etching that is perpendicular to the surface of the copper conductor. M Metallic Resist A surface plated onto a copper conductor that will not corrode or be etched by alkaline etchant, usually the metal is solder or tin. Multilayer Board Printed circuit board composed of several layers of laminate and circuitry. Muriatic Acid See Hydrochloric Acid. O Outlayer Etching The etching of the filed copper on the exterior of a printed circuit board leaving the circuitry on the board. Oxidation A chemical reaction whereby oxygen is used to release or change the state of a metallic ion. A fundamental chemical reaction in the etching process. P
Panel Printed circuit board. Often used in determining the capacity of a PWD facility, e.g. "total panels" is a unit of measurement that refers to the total volume of boards manufactured. Panel Size A measurement of the largest possible circuit board that can be manufactured by a PWB manufacturer. Dictates not only the size and configuration of the etcher but the processes within the entire facility. Persulphates A chemical compound with sodium or ammonium that was used as an etchant at the beginning of the PWB business. Currently used as a micro etchant in pre-clean, electroless copper, direct metalization processes. pH A measurement of the relative acidity or alkalinity of a chemical. pH Controller A component on an alkaline etcher used to control the pH within the etching chamber. pH is increased usually by injecting anhydrous ammonia gas and decreased by venting. Photo Resist A polymer that is activated using ultra violet radiation. It is used to put a circuit image on a printed circuit board. It can be a positive or negative image. It's main function is to keep acid from adhering to or attacking the copper under the developed photo resist. Similar to Dry Film. Plated Through Hole See PTH. Pop It Valve A cone-shaped valve in bellows-type replenisher pumps. The valve determines the direction of flow of the fluid from the bellows. PTH "Plated Through Hole" refers to a technology that deposits copper on the inside of holes drilled in a circuit board. Puddling Etchant remaining on top of board in horizontal etching. Puddling blocks oxidation and prevents etching. PWB Abbreviation for "printed wire board" or "printed circuit board". R
Replenisher Pump A pump that transfers fluid (alkaline replenisher) from a storage unit (drums, totes, bulk tank) into the Flood Rinse Module. The pump is activated by a controller that reacts to changes of Baume' or specific gravity in the etchant. Resist A material that is impervious to or "resists" attack by etchant. Resist Strip Module A chamber where photo resist or dry film is removed from PWB just prior to outer layer etching or just after inner layer etching. Resist Stripper An alkaline chemical that removes resist or dry film from a printed circuit board. Resist Stripping The process of removing a resist or dry film from a printed circuit board. Rinse Chamber Module attached to a D. E. S. or S. E. S. line that sprays water on the panels for cleaning purposes after exiting the Floor rinse Module, the resist strip module, or the solder strip module. S
S.E.S. "Strip the resist, Etch the outer layer, Strip the metallic resist" (solder or tin); S.E.S. is the conveyorized process that prepares the outer layers for solder mask. Sludging An unintended solidification of the etching solution as a result of copper precipitation caused by out of balance conditions that can occur in etchants. SMOBC "Solder mask over bare copper." SMOBC is a type of printed circuit board that has the metallic resist removed. Copper conductor circuits are protected from the atmosphere via a polymer coating. SMT "Surface mount technology" refers to a PWB on which components are soldered or mounted on the exterior surface of the board only - an emerging technology. Solder Brightner See Finishing Solution. Solder Mask Over Bare Copper See SMOBC. Solder Mask A resin type resist that encapsulates the printed circuit board, so when it is being assembled, molten solder will not stick to the board except on pad holes or lead frames. Solder Strip Module A chamber where solder or tin (the metallic resist) is removed from the panel prior to solder mask. Solder Stripper A chemical used to remove solder from 1) the top of copper conductor circuits and 2) from the printed through holes in a PWB after outer layer etching. The process is known as Solder Stripping. Specific Gravity A method for measuring the copper concentration in etching solution. Similar to Baume'. Spent Etchant Etching solution that can no longer efficiently etch boards due to excess copper concentration or loss of chlorides or other activating constituents. Spray Manifolds Interconnected series of pipes that house the spray nozzles. Etchant passes through the manifold and nozzles before being sprayed on to panels. Spray Nozzles The component on a spray etcher that discharges the etchant solution onto the circuit boards passing through the etching chamber on the conveyor. Spray Pattern Etchant distribution pattern formed by the spray nozzle configuration. See also Fan Spray Pattern and Conical Spray Pattern. Starter A proprietary form of etching chemistry used to initiate the etching process. Stripping Chamber See Stripping Module. Stripping Module An enclosed unit where a resist (either metallic or polymer type) is removed from a printed circuit board. The type of resist being removed determines the type of chemistry within the module same as Stripping Chamber. Surface Mount Technology See SMT. T
Tin Stripper A proprietary chemical used to remove tin from the top of either a copper conductor or a plated through hole on a printed circuit board after outer layer etching. U Undercut The amount of lateral etching as the etchant etches downward to form spaces and conductors. V Vertical Etcher Etcher in which panel is transported vertically through the etching chamber and flood rinse module. Spray nozzles and the spray manifold are located on the sides of the etching chamber. Vias A PTH that provides electrical continuity only, not used as a component mount. (Short for Viaduct.) |
