Glossary
ACID
A hydrogen-containing substance which breaks down upon solution in water to produce hydrogen ions. Acid strength is determined by the quantity of hydrogen irons which are released into the solution. The higher the concentration of hydrogen, the stronger the acid.
ACTIVATED
The condition of a compound or mixture of compounds having higher chemical activity than that normally found with the compound or mixture.
An example is the addition of an activator to rosin to increase fluxing activity.
ALLOY
A combination of two or more metal elements. An example is 63% tin plus 37% lead, a solder alloy.
AUTO IGNITION POINT
The temperature at which vapour from a material in air will spontaneously burst into flame.
BOILING POINT
The temperature of a liquid at which its vapour pressure is equal to the pressure of the atmosphere surrounding the fluid.
BONDING PAD
A metalized area at the end of a thin metal strip or on a semiconductor to which the connection is made.
BRAZING
A group of joining processes wherein the filler metal is a non ferrous metal or alloy whose melting point is typical higher than 1000°F but lower than that of the metals or alloys to be joined. At one extreme, brazing is similar to soldering and is sometimes called hard soldering.
BURNOFF
Removal of electroless copper as a result of excessive current. Usually occurs at edges of holes and causes plating failure in the hole.
CAPILLARY ACTION
The interaction between a liquid and a small diameter channel or opening in a solid. Because of the physics involved, if the liquid wets the sides of the solid channel, surface tension will draw the liquid up into the capillary channel.
CATHODE
The negative pole of a plating cell. It is the physical entity of the plating set-up at which positively charged ions leave the plating solution. The cathode is normally the object of the plating, i.e. a metal is deposited on the cathode.
CHEMICAL STABILITY
That characteristic of a compound which describes its ability to retain, without modification, its chemical properties over a long period of time.
CIRCUIT
The interconnection of a number of devices in one or more closed paths to perform a desired electrical or electronic function.
COLD SOLDER JOINT
Incorrectly made solder joint caused either by a soldering iron with too low a tip temperature or by heating of the solder rather than the metals to be joined.
COMPONENT
Any part placed on a printed circuit assembly i.e. resistor, capacitor, diode.
COMPOUND
A homogenous pure substance composed of two or more essentially different chemical elements, which are present in definite proportions.
CONTAMINANT
An impurity or foreign substance present in a material or on a surface which affects performance in the material or circuit.
CORROSION
The most common kind of corrosion is that of rusting.This is known as atmospheric corrosion wherein the oxygen of the atmosphere reacts with the material in question. Most metals with the exception of the noble metals such as gold, can be oxidized by atmospheric oxygen.
CREEP STRENGTH
A characteristic of a material which describes its strength and resistance to elongation i.e. stretching at low loads. This characteristic can be measured either as the load to fracture the sample at a given temperature, or the load that will produce a given percent of stretch, or elongation, at a given temperature.
DEWETTING
A condition which results when molten solder has coated a surface and then receded, leaving irregularly shaped mounds of solder separated by areas covered with a thin solder film, base metal is not exposed.
DIP SOLDERING
The process of soldering all components on a board at one time by dipping the board in a solder pot. The board is not dipped deeply enough to immerse components.
DROSS
Metal oxides and other entrapped impurities which float in or on the surface of a molten metal bath. In the case of solder, it would include the oxides of lead and tin, in addition to non-metallic impurities such as flux residues that were dragged into the solder bath, and oxides of any metal impurities found in the solder.
ELEMENT
A substance which cannot be decomposed or otherwise modified by ordinary types of chemical processes. Neither can an element be made by chemical union.
EUTECTIC
When applied to an alloy, eutectic refers to the composition of an alloy which has the lowest melting pint of a series. For example in the tin/lead system, Sn63/PB37 is the eutectic. This is the alloy composition of all those in the Sn/Pb system which has the lowest liquidus.
EVAPORATION
A physical process by which a liquid loses material to the atmosphere surrounding it. Evaporation is caused by the motion of the molecules of the liquid.
FLASH POINT
Temperature at which a volatile liquid mixes with air in such proportions as to produce flammable gaseous mixture. The mixture will flash when exposed to a flame or spark but will not necessarily continue to support combustion.
FLUX
As used in soldering, i.e. a material which cleans metal surfaces of absorbed gases, oxide films and other tarnishes. The flux also reduces the surface tension of the molten solder and the metal to be soldering, so that the solder may flow and wet the metal surface.
FREEZING POINT
The temperature at which a previously molten material solidifies, or becomes completely solid.
HOT AIR LEVELLING
Process used in solder dipping of bare copper circuitry in which high velocity air is used to blow solder clear from plated through holes and to minimize solder thicknesses.
ICICLING
The formation of solder spikes resulting from poor drain off of liquid solder following wave or dip soldering of printed circuit boards and assemblies. Poor solderability of the surfaces to be soldered and contaminated solder is frequent causes of icicling.
INORGANIC
When applied to chemistry, refers to the chemistry of those compounds found in nature or synthesized by man which do not depend essentially upon chemistry of carbon for their properties.
JUNCTION
A joining of two different semiconductors or of semiconductor and a metal.
LEAKAGE
Loss of insulation between between conductors on a board. May be due to improper cleaning procedures that leave conductive residues.
LIQUIDUS
The temperature at which an alloy is completely molten.
METALURGY
The area concerned with the extraction of metals for their orders and the refiring of these metals is known as the process of metalurgy.
MOLECULE
The smallest quantity of matter which can exist by itself and be recognizable as a particle of the original material. A molecule retains all the properties of the bulk substance from which it came.
ORGANIC HALIDES
An organic compound containing halogens.
PAD
Area of copper surrounding a hole in a board to be used for lead of component, or for insertion of interconnecting wire. Provides area for solder bonding.
PCB
A printed circuit board, at almost any stage in production from raw material to the finished assembly complete with components.
PICK AND PLACE EQUIPMENT
The automated pick up and placement of discrete active and passive devices on ceramic substrates.
PLASTIC RANGE
Refers to a range of temperature in which metal or alloy can be mechanically worked without danger or cracking of the material.
REFLOW SOLDERING
A method in which a solder joint is made by melting the solder coatings on them mating surfaces.
RESIN
A solid or semi solid organic compound lacking a crystalline structure. Resins are characterised by not having definite and sharp melting points, are not usually conductors of electricity.
ROSIN
A naturally occurring resin usually associated as a components of pine sap. Rosin alone is a mild flux for soldering operations.
SHELF LIFE
Length of time under specified conditions that a stored material in original, unopened containers retains usability.
SOLDER
A metal or metal alloy usually having a low melting point, used to join other metals having higher melting points than the solder together.
SOLDER PASTE
Homogenous combinations of solder and flux, solvent and gelling or suspension agent for automated production of solder joints.
SOLDER PREFORMS
Manufactured solder configurations containing a predetermined quantity of alloy, with or without a flux core or coating.
SOLDER RESISTS
Coatings which mask off a surface which insulate those areas of a circuit where soldering is not desired.
SOLIDUS
The temperature at which a metal alloy begins to melt.
SPECIFIC GRAVITY
The ratio of the density of a material to the density of water.
SURFACE MOUNT DEVICES
Electronic components, either active or passive which do not have separate leads. The terminal leads are part of the component body, allowing direct mounting on the surface of the printed wiring boards.
TENSILE STRENGTH
The characteristic of a material which describes its resistance to fracture when the material is being stretched. I.e. Under a tensile load.
THIXOTROPIC
The characteristic of a liquid or gel that is viscous when static, yet fluid when physically worked.
TINNING
Coating of a terminal, lead or conductive pattern with tin or solder alloy to improve maintain solderability or to aid in the soldering operation.
VISCOSITY
The measure of resistance of a fluid to flow- though a specific orifice or in a rotational viscometer.
VOLATILE
Used to describe materials which have a relatively high evaporation rate or a tendency to evaporate.
WATER BASED
A description of a liquidus system where the primary solvent is water.
WAVE SOLDERING
The technique of soldering components to a board by passing the board over a wave of solder in a soldering pot. The wave is maintained above the level of the pot by solder being pumped through a manifold in the bottom of the pot.
WETTING
A physical phenomenon of liquids usually in contact with solids, whereas the surface tension of the liquid has been reduced so that the liquid flows and makes intimate contact in a very thin layer over the entire substrate surface.