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VENTS: See Halogenated hydrocarbon solvents. CHOPPED BOND: Those bonds with excessive deformation such that the strength of the bond is greatly reduced. CHUCK: Portion of the bonding machine that holds the unit to be bonded. CIRCUIT: The interconnection of a number of electrical elements and/or devices, performing the desired electrical functions. A circuit must contain one or more active elements (devices) in order to distinguish it from a network. CIRCUMFERENTIAL SEPARATION:

A crack formed around the circumference of a plated through hole or any other cylindrical interconnection made by plating or solder. CLAD: A condition of one or both sides of the base material characterized by a thin layer of bonded metal foil. CLAMPLNG FORCE: Force applied to a bonding tool to effect a bond. CLEAN ROOM: A special manufacturing area where the air is filtered to

remove dust particles and precautionary measures are used to keep contamination away from the unprotected circuit during processing. CLINCH: A method of mechanically securing components prior to soldering, by bending that portion of the component lead that extends beyond the lip of the mounting hole, against a pad area. CLINCHED LEAD: The formed portion of the component lead extending through a hole in a printed board which prevents the component from falling out during the solder process. COATED METAL-CORE SUBSTRATE:

A substrate consisting of a glossy, inorganic coating bonded to metal by firing at a temperature about 500°C. COEFFICIENT: The ratio of change under specified conditions of temperature, length, etc. COEFFICIENT OF THERMAL EXPAN-

SION: The ratio of the change in dimensions to the change in temperature. COEFFICIENT OF VISCOSITY: A measure of the tendency of a fluid to resist shear. The unit of viscosity is the poise. CO-FIRING: Processing the thick-film conductors and resistors through the firing cycle at the same time. COINED: A screen which contains the impression of a substrate because it has been subject to abuse is said to be coined. The term can also refer to a screen manufactured with a coined impression for the purpose of screening media in a special designed substrate with a cavity that standard screens cannot achieve. It is also used to describe the process by which the base of a package has been formed. COINED LEAD: A cylindrical lead that

with metal mask. CONTACT RESISTANCE: In electronic elements, such as capacitors or resistors, the apparent resistance between the terminating electrode and the body of the device. The electrical resistance between two mating conductors. CONTACT SPACING: The centerlineto-centerline spacing of adjacent contact areas. CONTINUITY: The uninterrupted path of current flow in an electrical circuit. CONTINUOUS BELT FURNACE: A firing furnace that has a continuous belt carrying the unfired substrates through the firing cycle. CONTROLLING COLLAPSE: Controlling the reduction in height of the solder balls in a flip-chip processing operation. COORDINATOGRAPH: A drafting machine of great accuracy used in making original artwork for integrated circuits or hybrid microcircuits COPLANAR LEADS (FLAT LEADS):

Ribbon-type leads extending from the sides of the circuit package, all lying in the same plane. COPLANARITY: Property of lying in the same plane. COPOLYMER: A compound, resulting from the chemical reaction, polymerization, of two chemically different monomers with one another. The resulting larger molecules contain repeating structural units of the original molecules. CORONA: The flow of small erratic current pulses resulting from discharges in voids in a dielectric during the voltage stress; also discharge re-

sulting from ionisation of gas surrounding a conductor (frequently luminous) which occurs when the potential gradient exceeds a certain value but is not sufficient to cause sparking. CORROSIVITY (CONDUCTOR TRACES):

That characteristic of a conductor metallization on a substrate which causes a resistance change greater than 10 percent, and/or causes it to show visible evidence of corrosion with discoloration when in physical touch with an (epoxy) adhesive, and is concurrently exposed to moderate humidity and temperature effects, anytime after completed cure schedule. COUPLING CAPACITOR: A capacitor that is used to block DC signals, and to pass high-frequency signals between parts of an electronic circuit. COVER: The top portion of a package to be joined to the bottom portion to form a sealed unit. A cover has an internal depth (sometimes referred to as a cavity) distinguishing it from a lid which is flat COVER LAYER: Outer layer of insulating material covering the conductive pattern on the printed board. COVER SEAL: It denotes the seal at the perimeter of the cover or lid, when joined to the package body; or in hybrid fabrication, the cover-sealing operation itself. The seal may be accomplished by resistance welding, cold weld (solid-phase bond), brazing, soldering, or by other means. CRACKING: Breaks in the metallic and/ or nonmetallic layers extending through to an underlying surface. CRATERING: Defect in which portion of the chip under ultrasonic bond is

torn loose by excessive amount of energy transmitted through the wire bond leaving a pit. CRAZING: Fine cracks which may extend on or through layers of plastic or glass materials. CREEP: The dimensional change with time of a material under load. CRITICAL PRESSURE: The pressure under which a substrate may exist as a gas in equilibrium with liquid at the critical temperature. CRITICAL TEMPERATURE: The temperature above which the gas cannot be liquefied by pressure alone. CROSSOVER: The transverse crossing of metallization paths without mutual electrical contact and achieved by the deposition of an insulating layer between the conducting paths at the area of crossing. CROSSTALK: Signals from one line leaking into another nearby conductor because of capacitance or inductive coupling or both (e.g., owing to the capacitance of a thick-fiim crossover). CRYOGENICS: The science involving phenomena at very low temperatures less than -100°C. CRYSTAL GROWTH: The formation of crystals in a material over a period of time and at an established temperature. C-STAGED RESIN (C-STAGE): Completed cured resin. CURE TIME: The total elapsed time between the addition of a catalyst and a complete hardening of a material; also the time for hardening of premixed, frozen, or refrigerated epoxy adhesives.