I/O connectors Connectors that are the interface between a PCA’s input/output signals and the outside world.

IC = integrated circuit (may be upper or lower-case) A device in which all the interconnected electronic circuit elements that enable the component to perform a specific function are fabricated on a single substrate of semiconductor material, most commonly silicon. Produced , called a ‘chip’ or ‘die’, which is placed in a plastic or metal package with terminals for external connections. Commonly referred to as a die or chip.

icicle A projection from a solder joint, with a conical shape and a sharp point, which is not acceptable even though it does not make contact with another conductor. (Also referred to as a ‘peak’)

ICT = In-Circuit Test An electrical test of an assembly in which each component is tested individually for electrical function, to verify correct placement and orientation. Connections to each part are usually made by a bed-of-nails fixture, using a test method which effectively isolates the component from the rest of the circuitry, allowing it to be tested as a stand-alone device.

IEC = International Electrotechnical Commission The IEC is a world organization that prepares and publishes standards for electrical electronic, and related technologies.

In-Circuit Test See ICT

induction soldering An interconnect method in which solder, generally as preforms, is reflowed.

industry standard Processes, procedures, guidelines, and data formats that are widely used and recognized throughout the printed circuit industry.

infant mortal(ity) A marginal component, circuit board, or solder joint that was not detected during production test or inspection, and fails a short time after being put into operation.

ink pattern Applied to the surface of a circuit board through a screen or stencil, ink can be used to add markings or as a resist to define an interconnection pattern.

in-line machine The term ‘in-line’ is applied to items of equipment that are arranged within a production flow line which uses conveyerised board handling. In fabrication, such conveyor systems are frequently used between etching, stripping and cleaning operations; the approach is used almost everywhere in board assembly.

In-line machines may operate either a continuous process (as with etching or reflow soldering) or a discrete process (such as printing or component placement) where the board is removed from the conveyor, operated upon, and then returned. One requirement for in-line configuration is that the throughput of connected machines should be compatible: in-line machines are unusual in semi-conductor back-end processing, because wafer sawing, die bond, wire bond and encapsulation have different cycle times

Input/Output (I/O) Refers to the number of interfaces (pins) on a device which receive or transmit data.

inspection overlay A positive or negative transparency made from the production master and used as an inspection tool by placing over the board and checking for variances between the overlay pattern and the board pattern.

insufficient (solder) A soldered connection where the conductors have the appearance of being tinned and wetted together without an adequate solder fillet; or there is incomplete coverage of one or more of the metal surfaces being joined.

insulation resistance The electrical resistance between any pair of conductors which are intended to be isolated, such as connector contacts or printed wiring board conductor tracks.

insulator A non-metallic material designed to prevent current flow.

integration The marriage of an operational PCA with the system or product with which it is to function.

intelligent data Electronic data that contains physical or functional information about an item (such as an electronic part), and also links to other information.

interchangeability The characteristic of a design that allows direct replacement of one item with another without requiring any modifications.

interconnection escapes Conductor paths provided in a device footprint to give access to the part’s terminals.

interconnection The physical wiring or circuit pattern between components and individual units or subassemblies.

intermetallic layer Refers to the actual bond formed in soldering from the interdiffusion of two or more metals (e.g. copper/tin). The intermetallic layer is the most brittle part of the joint, and increases in depth in logarithmic proportion to both time and temperature during the soldering process. (Staying on the joint twice as long, or with an iron twice as hot, causes the intermetallic layer to become 10 times thicker.) The ideal intermetallic layer is continuous but thin.

internal layer A conductive pattern which is contained entirely within a multi-layer printed board, performing an interconnection function which is not generally visible from the surface. Defects in metallisation may result in open-circuit or short-circuit conditions, so internal layers are always subject to rigorous inspection before laminating.

IPC Until 1999 IPC was the Institute for Interconnecting and Packaging Electronic Circuits. The new name is accompanied with an identity statement – Association Connecting Electronics Industries. IPC is a leading industry association and the final US authority on how to design and manufacture printed wiring. IPC develops and distributes standards, as well as other information of value to designers, users, suppliers, and fabricators.

IR emitter A source of light energy in the infrared spectrum.

IR reflow Use of infrared energy to bring solder to its melting point.

ISO = International Organization for Standardization The stated mission of ISO is to promote the development of quality standards and related activities in the world to facilitate the international exchange of goods and services.

ISO 14001: An environmental management system (EMS) is a systematic approach to dealing with the environmental impacts of an organisation. It is a framework that enables an organisation of any size or type to control the impact of its activities, products or services on the natural environment. ISO 14001 Environmental management systems is an international standard that specifies the requirements.

isotropic conductive adhesive (ICA) The term isotropic means that the material has similar properties in all directions, so that an ICA may be used for the same sorts of application as a solder joint. However, the conductivity of adhesives filled with metallic particles is very much less (typically in the range 1–10% at best) than the metal from which it is formulated, despite containing perhaps 50–60% of metallic powder. See also anisotropic conductive adhesive.