Glossary of Industry Terms

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

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Absolute Zero
The temperature at which thermal energy is at a minimum. Defined as 0 (zero) Kelvin, calculated to be -273.15°C. See also Celsius, Fahrenheit, Kelvin, Rankine
Adapter
A mechanism or device for attaching non-mating parts.
ASCII
American Standard Code for Information Interchange. A seven- or eight-bit code used to represent alphanumeric characters. It is the standard code used for communications between data processing systems and associated equipment.
ASME
American Society of Mechanical Engineers.
ASTM
American Society for Testing and Materials.
Average Deviation
Also referred to as the “AD”, this phrase is a statistic used to describe the average difference between a previously measured temperature and the currently measured temperature. See also Deviation, Maximum Deviation, Slope, Statistics
AWG
American Wire Gage.

B

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Belt-Speed
This is the term we use to refer to the oven’s conveyor speed. It is sometimes abbreviated as “BS”. It is the mechanism by which the product is moved through the oven.
Boiling Point
The temperature at which a substance in the liquid state transforms to the gaseous state. Commonly refers to the boiling point of water – 100°C/212°F at sea-level on a standard day. See also Melting Point
BTU
British Thermal Unit. The quantity of thermal energy required to raise one pound of water at its maximum density, 1°F. One BTU is equivalent to .293 watt hours, or 252 calories. One kilowatt hour is equivalent to 3412 BTU.

C

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Calibration
The process of adjusting an instrument or compiling a deviation chart so that its reading can be correlated to the actual value being measured.
Cavitation
The boiling point of a liquid caused by a decrease in the pressure rather than an increase in temperature.
Celsius
aka. Centigrade, a temperature scale defined by 0° at the icing point, and 100° at the boiling point of water at sea level on a standard day. See also Fahrenheit, Kelvin, Rankine
Convection
Heat transfer that occurs at the interface of a solid and fluid or gas due to temperature differences.
Convection/IR
A type of reflow oven that uses a combination of convection and radiation to transfer heat.
Cooldown
The period in the reflow process, after peak temperature, during which the temperature falls to the point where the solder joints solidify or freeze.

D

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Density
Mass per unit of volume of a substance.
Deviation
The difference between the value of the controlled variable (KICprobe temperatures) and the value (target temperatures) at which it is being controlled. See also Average Deviation, Maximum Deviation, Slope, Statistics

E

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Eutectic Temperature
The lowest possible melting point of a mixture of alloys.

F

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Fahrenheit
A temperature scale defined by 32° at the icing point and 212° at the boiling point of water at sea level on a standard day. See also Celsius, Kelvin, Rankine
Fillet
The concave junction formed by the solder between the footprint pad and the surface mount component lead or pad.
Forced Convection
A type of reflow oven in which the principal heat transfer mechanism is convection.

H

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Heat Sink
A body which can absorb thermal energy.
Heat Transfer
The process of thermal energy flowing from a body of high energy to a body of lower energy. Means of transfer are: Conduction, Convection, Radiation.
Heat
Thermal energy. Heat is expressed in units of calories or BTUs.

I

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Infrared Radiation
The band of electromagnetic wavelengths lying between the extreme of the visible and the shortest microwaves. The strong absorbtion of infrared by many substances renders it a useful means of heat energy transfer.
ISA
Instrument Society of America.
Isothermal
A process or area that is a constant temperature.

J

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Joule
The basic unit of thermal energy.

K

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Kelvin
The unit of absolute or thermodynamic temperature scale based upon the Celsius scale with 100 units between the icing point and boiling point of water. 0°C = 273.15K (there is no degree symbol used with the Kelvin scale). See also Celsius, Fahrenheit, Rankine

L

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Laser Reflow Soldering
Focused heat energy from a CO2, Nd:YAG, etc. source that is directed to specific points on the printed circuit board (PCB) to reflow joints very quickly. See also Reflow Soldering, Vapor Phase Reflow Soldering
Latent Heat
Expressed in BTU per second. The amount of heat needed (absorbed) to convert a point of boiling water to a pound of steam.

M

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Maximum Deviation
Also referred to as the “MD”, this phrase is a statistic used to describe the greatest difference between a previously measured temperature and the currently measured temperature, of all the points considered. See also Average Deviation, Deviation, Slope, Statistics
Mean Temperature
The average of the maximum and minimum temperatures of a process equilibrium.
Melting Point
The temperatures at which a substance transforms from a solid state to a liquid state. See also Boiling Point

O

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Oven
The oven we refer to is a conveyorized machine used to introduce temperature variations in a product through the use of convection, conduction, or radiation heating methods.

P

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PCB
Printed Circuit Board, aka. Printed Wiring Board (PWB).
Potentiometer
A variable resistor often used to control a circuit.
Preheat
Generally referring to a process portion of the reflow heat curve where the product is heated from ambient at a determined rate so that the shock of sudden reflow temperatures is avoided.
Profile
A graph of time versus temperature.
Profile Prediction
This is the phrase that KIC uses to describe the ability of using a known profile to simulate oven recipe changes on the computer.

R

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Rankine
An absolute scale based upon the Fahrenheit scale with 180° between the icing point and the boiling point of water. 0°F = 459.67°R. See also Celsius, Fahrenheit, Kelvin
Recipe
The “recipe” is the term KIC uses to describe what some call the “process.” It refers to the combination of oven temperatures setpoints and conveyor speed.
Reflow Soldering
A process for joining parts to a substrate by placing parts’ leads into a solder paste and then reflowing the solder and making the interconnection. Also referred to as the reflow process. See also Laser Reflow Soldering, Vapor Phase Reflow Soldering

S

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Seebeck Effect
When a circuit is formed by a junction of two dissimilar metals and the junctions are held at different temperatures, a current will flow in the circuit caused by the difference in temperature between the two junctions. This is the principle behind how thermocouples operate. See also Thermocouple
Setpoint
The temperature at which a controller is set to control a system.
Slope
The term “slope” is a statistic used to describe the rate of temperature rise or fall over a period of time (temperature over time). See also Average Deviation, Deviation, Maximum Deviation, Statistics
SMOBC
SolderMask Over Bare Copper. A printed wiring technology that protects bare copper connectors with a mask exposing only the component land patterns to solder plating.
SMT
Surface Mount Technology. A manufacturing process whereby small electronic components are mounted on a thin layer of solder paste atop a printed circuit board, then heated until the solder reflow, attaching the components to the board.
Span
The difference between the upper and lower limits of a range expressed in the same units as the range.
Specific Heat
The ratio of thermal energy required to raise the temperature of a body 1° to the thermal energy required to raise an equal mass of water 1°.
Statistics
The term “statistics” is used to describe limits and variations used in conjunction with surface mount technology (SMT) thermal profiling. These include “time-above”, “time-between”, maximum and minimum temperatures.
Surface Tension
The molecular force existing in the surface film of all liquids, which tends to contract the volume into a form consuming the least surface area.

T

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Thermal Conductivity
The property of a material to conduct heat in the form of thermal energy.
Thermocouple
Often referred to as “TC,” the junction of two dissimilar metals which has a voltage output proportional to the difference in temperature between the hot junction and the cold junction (lead wires). See also Seebeck Effect

V

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Vapor Phase Reflow Soldering
A type of reflow soldering in which the printed circuit board (PCB) assembly is passed through a vaporized inert fluorocarbon. The latent heat given up when the fluorocarbon condenses causes the solder to reflow. See also Laser Reflow Soldering, Reflow Soldering
Virtual Profiling
Also referred to as “VP”, this phrase is used to describe the ability of the computer to perpetually monitor the thermal profiles or real product using computer simulation.

W

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Wetting
A physical phenomenon of liquids, usually in contact with solids, wherein 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. Regarding wetting of a metal surface by a solder, flux reduces the surface tension of the metal surface and the solder, resulting in the droplets of solder collapsing into a very thin film, spreading and making intimate contact over the entire surface.
Wetting Agent
A chemical material added to a liquid solution to reduce surface tension. The effect of the reduction of surface tension is to increase the power of the liquid mixture or solution to wet an object on which it is placed.
Wicking
The flow of solder via capillary action along conductors under insulation, or through conductors via holes.