Accelerator - An organic compound which is added to an epoxy resin to shorten the cure time.
Additive Plating - Processing a hybrid circuit substrate by sequentially plating conductive, resistive, and insulative materials, each through a mask, thus defining the areas of traces, pads, and elements.
Assembly/Rework - Terms denoting joining and replacement processes of microelectronic components. Assembly refers to the initial attachment of device and interconnections to the package. Rework refers to the removal of a device including interconnections, preparation of the joining site for a new device, and rejoining of the new device. Rework is necessary for either repair or engineering change.
Back-End-Of-The-Line (BEOL) - That portion of the integrated circuit fabrication where the active components (transistors, resistors, etc.) are interconnected with wiring on the wafer. It includes contacts, insulator, metal levels, and bonding sites for chip-to-package connections. Dicing the wafer into individual integrated circuit chips is also a BEOL process. The front-end-of-the-line (FEOL) denotes the first portion of the fabrication where the individual devices (transistors, resistors, etc.) are patterned in the semiconductor.
Board - This package element can best be defined as an organic printed-circuit card or board on which smaller cards or modules can be mounted. Its connections to the next higher level involve discrete wire or cables.
Chip - The uncased and normally leadless form of an electronic component part, either passive or active, discrete or integrated. Also referred to as a die.
Circuit-Board Packaging - Packaging of chips by the use of organic printed-circuit boards. See Printed-Circuit Board.
Coated-Metal Core Substrate - A substrate consisting of an organic or inorganic insulation coating bonded to metal. Insulated surface or surfaces are used for circuit deposition.
Coefficient of Thermal Expansion (CTE) - The ratio of the change in dimensions to the change in temperature-per-unit starting length, usually expressed in cm/cm/'C.
Conformal Coating - A thin non-conductive coating, either plastic or inorganic, applied to a circuit for environmental and/or mechanical protection.
Connections - The connections belonging to nets interconnecting logic units on a given package level - including connections to terminals on that level - connecting it to the next higher package level.
Convection - Transmission of thermal energy from a hotter to a cooler region through a moving medium, such as air or water.
Crossover - The transverse crossing of metallization paths without mutual electrical contact. This is achieved by the deposition of an insulating layer between the conducting pats at the area of crossing.
Curing Agent - An inorganic or organic compound which initiates the polymerization of a resin.
Curing Cycle - For a thermosetting material, commonly a resin compound such as a bonding adhesive, it is the combination of total time-temperature profile to achieve the desired result; for example, the complete irreversible hardening of the material, resulting in a strong board.
Die - Integrated circuit chip as cut (diced) from finished wafer. See Chip.
Dielectric - Material that does not conduct electricity. Generally used for making capacitors, insulating conductors (as in crossover and multilayerd circuits), and for encapsulating circuits.
Dielectric Constant - The term used to describe a material's ability to store charge when used as a capacitor dielectric. It is the ratio of the charge that would be stored with free space to that stored with the material in question as the dielectric.
Dielectric Loss - The power dissipated by a dielectric as the friction of its molecules opposes the molecular motion produced by an alternative electric field.
Electroless Plating - Metal deposition, usually in an aqueous medium, which proceeds by an exchange reaction between metal complexes in the solution and the particular metal to be coated; the reaction does not require externally applied electric current.
Electroplating - Deposition of an adherent metallic coating onto a conductive object placed into an electrolytic bath composed of a solution of the salt of the metal to be plated. Using the terminal as the anode (possibly of the same metal as one used for plating), a DC current is passed through the solution affecting transfer of metal ions onto the cathodic surface.
Failure - The temporary or permanent impairment of device function caused by physical, chemical, mechanical, electrical, or electromagnetic disturbance or damage.
Filler - A substance, usually ceramic or metal powder, used to modify the properties of fluids or polymers. FR-4 - Electronic Industries Association's designation for a fire retardant epoxy resin/glass cloth laminate. By common usage, the resin for such a laminate.
Glass Transition Temperature - In polymer or glass chemistry, the temperature corresponding to the glass-to-liquid transition, below which the thermal expansion coefficient is low and nearly constant, and above which it is very high.
Ground Plane - A conductive layer on a substrate or buried within a substrate that connects a number of points to one or more grounding electrodes.
Insulators - A class of materials with high resistivity. Materials that do not conduct electricity. Materials with resistivity values of over 106ohms-cm are generally classified as insulators.
Integrated Circuit - A microcircuit (monolithic) consisting of interconnected elements inseparably associated and formed in situ on or within a single substrate (usually silicon) to perform an electronic circuit function.
Interconnection - The conductive path required to achieve connection from a circuit element to the rest of the circuit.
Mask - The photographic negative that serves as the master for making thick-film screens and thin-film patterns.
Metallization - A film pattern (single or multilayer) of conductive material deposited on a substrate to interconnect electronic components.
Multichip Module (MCM) - A module or package capable of supporting several chips on a single package. Most multichip packages are made of ceramic.
Multichip Package - An electronic package that carries a number of chips and interconnects them through several layers of conductive patterns. Each one is separated by insulative layer and interconnected via holes.
Multilayer Substrates - Substrates that have buried conductors so that complex circuitry can be handled, using assembly processes similar to those used in multilayer ceramic capacitors. Fabricated either as a conventional MLC, or a cofired multilayer ceramic (CMC) hybrid structure, in high- and low-temperature versions.
Nonlinear Dielectric - A capacitor material that has a nonlinear capacitance-to-voltage relationship. Titanates (usually barium titanate) ceramic capacitors (Class II) are nonlinear dielectrics. NPO and Class I capacitors are linear by definition.
Package Delay - The time delays associated with the interconnections between components that complete logical make-up functions. Values depend on materials and distance.
Packaging Level - A member of a nested interconnected packaging hierarchy (e.g., chip, chip carrier, card, board in order of low to high level).
Photolithography - The generation of a pattern through a sequence of rubylith, photo-reduction, step-and-repeat, computer-aided design, or finally, state-of-the-art electron-beam technique. This procedure will generate a product (mask or otherwise) to become the primary tool in transferring an image onto a microelectronic substrate.
Plasma Etching - The action of an electrically conductive gas, (composed of ionized gas or molecules), to remove unwanted portion of conductive or insulative pattern.
Plating - A condensation of the word ELECTROPLATING or ELECTROLESS PLATING that describes the coating of a metal on a plastic or other surfaces with metal that is electrolytically or chemically deposited from a bath.
Polyimides - A class of resin compounds containing the NH group which are derived from ammonia and are "imidized" from [polyamic acid at temperatures high enough to initiate and complete the imide ring closure. Polyimides are useful as organic dielectric interlevel layers in VLSI technologies. They are mostly thermosetting ring-chain polymers, whose useful characteristics include perfect planarity as a (spun) film; high temperature tolerance; excellent weathering and mechanical-wear characteristics; and a low dielectric constant, a decided advantage in reducing propagation delays in multilayer hybrid circuits (faster switching).
Printed-Circuit Board (PCB) - A composite of organic and inorganic material with external and internal wiring allowing electronic components to be mechanically supported and electrically connected.
Resist - A protective coating that will keep another material from attaching or coating something, as in solder resist, plating resist, or photoresist.
Thick Film - A film deposited by screen printing processes and fired at high temperature to fuse into its final form. The basic processes of thick-film technology are screen printing and firing.
Thin Film - Thin film refers to a coating layer of thickness in the range of from a few (2-3) atomic layers to a few (1-5) microns (micrometers). The important feature distinguishing thin films from thick films, though, is not so much the difference in thickness as the method of deposition which takes place by a variety of techniques such as chemical vapor deposition, evaporation, or sputtering.
Thin-Film Packaging - An electronic package in which the conductors and/or insulators are fabricated using deposition and patterning techniques similar to those used for integrated circuit chips.
