Dewetting

A condition that occurs when molten solder has coated a surface and then receded, leaving irregularly shaped solder moulds separated by areas of thin solder film or voids.

DIP, Dual In-Line Package

A package intended for through-hole mounting that has two rows of leads extending at right angles from the base surface. The spacing between the leads (pitch) conforms to industry standards.

Double sided assembly

A packaging and interconnection structure with components mounted on both the primary and secondary sides.

Drawbridging/ Tombstoning

A solder open condition during reflow in which chip resistors and capacitor resemble a draw bridge. The affected component partially or fully stands vertical (hence the term tombstone).

Dual-wave Soldering

A wave soldering process that uses a turbulent wave with a subsequent laminar wave. The turbulent wave ensures complete solder coverage in tight areas and the laminar wave removes bridges and icicles. Designed for soldering surface mount devices glues to the bottom of the board.

Eutectic

The alloy of two or more metals that has a lower melting point than either of its constituents. Eutectic alloys, when heated, transform directly from a solid to a liquid and do not show pasty regions.

Fault profile

A description of the type and frequency of electrical faults most likely to be found on a populated PCB.

Fillet

The configuration of solder around a component lead and land. A blending or rounding of interconnecting conductors or leads which eliminates sharp corners.

Fine Pitch Component

Packages

Surface mount component packages with lead pitches less than 50 mil, more commonly 25 mils and under. fine pitch packages generally require vision system for accurate placement and lower solder paste prints than 50 mil pitch packages.

Flatpack

An integrated circuit package with gull wing or flat leads on two or four sides, normally on 0.050” centers, which are parallel to the component body. Lower pitches are generally referred to as fine pitch packages.

Flip-Chip Technology

A chip-on-board technology in which the silicon die is inverted and mounted directly to the printed wiring board. Solder is deposited on the bonding pads in vacuum. When inverted, they make contact with the corresponding board lands and the die rests directly above the board surface.

Flux

A chemically/physically active formation that is capable of enabling and promoting the wetting of metals with solder

Flux Residue

Particles of flux materials remaining on the PCB after soldering and cooling.

Flux solder connection

A solder joint characterized by entrapped flux that often causes high electrical resistance.

Flux, RMA

An organic acid of mildly activated rosin dissolved in isopropyl alcohol, which attacks and removes oxides from the metals to be soldered.

FPT, Fine pitch technology

The term used to describe the assembly technology for those IC packages having lead spacing of generally 0.65 mm(0.0256”) or less .

Functional Test

An electrical test of an entire assembly that simulates the intended function of the product.