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Dam
Bar:
A temporary part of the lead frame used to inhibit the flow
of plastic during the molding process for molded carrier ring
(MCR) and plastic quad flatpack (PQFP) components. The dam
bar is removed prior to testing or placing the component because
it is a part of the copper lead frame and thus shorts all
of the leads together.
DCA:
Direct Chip Attach. A chip-to-substrate connection intended
to reduce the first level of packaging. Here, the silicon
die is inverted and mounted directly to the PCB. Also referred
to as chip-on-board technology.
Defect:
Any nonconformance to specified requirements by a unit or
product.
Deionized Water:
Water that has been treated to remove ionized material.
Delamination:
A separation between plies within the base material, or between
the base material and the conductive foil, or both.
Dendritic Growth:
The metallic growth between pads in the presence of moisture
and an electrical bias.
Density:
The weight of a material in relationship to its volume.
Device:
An individual electrical circuit element that can't be further
reduced without destroying its intended function.
Dewetting:
A situation where a lead or pad was at one point in the soldering
process wetted by the solder, but due to extended time or
temperature, the presence of intermetallics, volatiles or
other causes, has become withdrawn from the wetted surface.
Die Bonder:
The placement machine for chips in a chip-on-board process
line.
Die Bonding:
The attachment of an integrated circuit chip to a substrate.
Die Sorter:
Equipment that picks die from a wafer and presents them for
their next process step. When used in reference to bare die
placement machines, the die are presented for pick by the
machine's placement nozzles.
Die:
Integrated circuit chip as diced or cut from the finished
wafer.
Dielectric:
Nonconducting material used to encapsulate circuitry and in
the manufacture of capacitors and printed circuit boards.
Diffusion:
A material transport phenomena that occurs in solids, and
is caused by the continual physical motion of atoms from one
position to another. This results in the flow of material
from regions of high concentraion to regions of low concentration.
Dilatant:
Fluid characterized by an increase in viscosity with an increasing
shear rate.
DIP Socket:
A connector for a Dual In-Line Package, or one that has its
leads in two parallel rows.
Direct
Chip Attach :
(see DCA)
Direct Chip Attach Module (DCAM):
A component type developed by IBM® consisting of a small substrate
with flip chips attached using the DCA
process. This small substrate, or module, is now a component
with solder pads on the bottom side that can be mounted to
a board using conventional surface mount processes.
Dispersants:
Organic and inorganic phosphates and polymers used in aqueous
cleaning to assist in the removal of insoluble particles.
Double-Sided Assembly:
A fully assembled PCB with components on both sides of the
substrate.
Downtime:
The period in which equipment is not producing product owing
to maintenance or failure.
Dross Content:
A measure of the cleanliness of solder powder.
Dross:
Any oxide or other contamination formed on the surface of
molten solder.
Dry Film Photoresist:
Solid photoresist applied to a surface by lamination of prefabricated
film.
Dual In-Line Package (DIP):
A package with two rows of leads extending at right angles
from the base with standard spacing between the leads and
row. This package is intended for through hole mounting.
Durometer:
The measure of rubber or plastic hardness, as with the squeegee
blade.
Dynamic Flex:
A flex circuit in constant motion, for example, in a printer
head.
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