ABSTRACT
HEAT CLEAN: The process of removing all organic material from glass cloth at approximately 343°C to 371°C for a period of time ranging up to 50 hours. HEAT COLUMN: The heating element in a eutectic die bonder or wire bonder used to bring the substrate up to the bonding temperature. HEAT FLUX: The outward flow of heat from a heat source. HEAT SINK: The supporting member to which electronic components or their substrate or their package bottom are attached. This is usually a heat conductive metal with the ability to rapidly transmit heat from the generating source (component). HEAT SOAK: Heating a circuit over a
period of time to allow all parts of the package and circuit to stabilize at the same temperature. HEEL (OF THE BOND): The part of the lead adjacent to the bond that has been deformed by the edge of the bonding tool used in making the bond. The back edge of the bond. HEEL BREAK: The rupture of the lead at the heel of the bond. HEEL CRACK: A crack across the width of the bond in the heel region. HELLUM LEAK CHECK: A check on the leak rate of a hermetically sealed device or package where the tracer gas employed is helium. The ionized gas outflow is analyzed instrumentally and the leak rate is expressed in units of atm-cm3/sec. HELIUM MASS SPECTROMETER: An
instrument of interest to the hybrid technologist as part of widely used leak detector systems. The mass spectrometer generally consists of means to ionize the helium in a vacuum, to accelerate and focus the ions by application of a fixed voltage, and then to separate the helium ions from other gas or vapor constituents, sorting them by magnetic deflection according to their atomic mass number or molecular weight. The helium atoms, after passing through a slit, are collected and cause a voltage to build up on the grid of a spectrometer tube; the resulting current, then, actuates the leak-rate detector. In practice, the leak-rate meter will deflect depending on the concentration of helium available from the jet probe held against an evacuated device under test exhibiting a fine leak and being connected
to a vacuum system. HERMETIC: A description of packages that provide an absolute seal against the infusion of water to prevent degradation of the electrical components within the package. The test for hermeticity is to observe leak rates when placed in a vacuum. A plastic encapsulation cannot be hermetic by definition because there is no internal volume of gas to escape. HERMETICITY: The ability of a package to prevent exchange of its internal gas with the external atmosphere. The figure of merit is the gaseous leak rate of the package measured in atm-cm3/ sec. HlGU-K CERAMIC: A ceramic dielectric composition (usually BaTi03) which exhibits large dielectric constants, and nonlinear voltage and temperature response. HIGH-PURITY ALUMINA: Alumina having over 99% purity of AI2O3. HIGH-RELIABILITY SOLDERING: A
statistically proven soldering technique that ensures a large probability of metallic joining success. HOLE DIAMETER: Normally refers to the diameter of the hole through the bonding tool. HOMOGENEOUS: Alike or uniform in composition. A thick-film composition that has settled out is not homogeneous, but after proper stirring it is. The opposite of heterogeneous. HORN: Cone-shaped member which transmits ultrasonic energy from transducer to bonding tool. HOSTILE ENVIRONMENT: An environment that has a degrading effect on an electronic circuit. HOT SPOT: A small area on a circuit
nonconductive after being subjected to the soldering temperature. INACTIVE METALLIZATION: Conductive metallized traces, paths, pads, fingers, or other areas on an active or passive substrate; metallized elements of a deposited pattern which are not being utilized at the time in the functioning circuit. INCLINED PLANE FURNACE: A resistor firing furnace having the hearth inclined so that a draft of oxidizing atmosphere will flow through the heated zones through natural convection means. INCOMPLETE BOND: A bond impression having dimensions less than normal size due to a portion of the bond impression being missing. INDIRECT EMULSION: Screen emulsion that is transferred to the screen surface from a plastic carrier or backing material. INDIRECT EMULSION SCREEN: A
screen whose emulsion is a separate sheet or film of material, attached by pressing into the mesh of the screen (as opposed to the direct emulsion type). INERT ATMOSPHERE: A gas atmosphere such as helium or nitrogen that is nonoxidizing or nonreducing of metals. INFANT MORTALITY (EARLY FAIL-
URES): The time regime during which hundreds of circuits may be failing at a decreasing rate (usually during the first few hundred hours of operafion). INFRARED: The band of electromagnetic wavelengths lying between the extreme of the visible (= 0.75 urn) and the shortest microwaves (= 1000
urn). Warm bodies emit the radiation and bodies which absorb the radiation are warmed. INJECTION MOLDED: Molding of electronic packages by injecting liquefied plastic into a mold. INK: Synonymous with "composition" and "paste" when relating to screenable thick-film materials, usually consisting of glass frit, metals, metal oxide, and solvents. INK BLENDING: See blending. IN-PROCESS: Some step in the manufacturing operation prior to final testing. INSERTION LOSS: The difference between the power received at the load before and after the insertion of apparatus at some point in the line. INSPECTION LOT: A quantity of hybrid microcircuits, representing a production lot, submitted for inspection at one time to determine compliance with the requirements and acceptance criteria of the applicable procurement doc-ument. Each inspection sublot of hybrid microcircuits should be a group of circuits identified as having common manufacturing experience through all significant manufacturing operations. INSULATED-METAL SUBSTRATE: A
substrate, such as one made of porcelainized steel, which is not sublect to size limitations and may have superior thermal dissipation characteristics. INSULATING LAYER: Used interchangeably with dielectric layers in hybrids, it is a thick-film or thin-film deposited layer of material separating or covering conductive layers. INSULATION RESISTANCE (IR): The re-
sistance to current flow when a poten-
