IPC A 610 EXAM LATES T 2023 -2024 ACTUAL EXAM 100 QUESTIONS AND CORRECT DETAILED ANSWERS WITH RATIONALES|AGRADE What is the purpose of Conformal Coating? - ANSWER - Conformal coatings can be used in a wide range of environments to protect printed circuit boards from moisture, salt spray, chemicals and temperature extremes in ord er to prevent such things as corrosion, mold growth, and electrical failures. Measuring wet coating (2) Wet Film Comb - ANSWER - Most common method to measure wet coating. The gauge consists of a series of combs with different distance between the marked p oints and the baseline. After placing the comb into the wet coating film, the thickness can be measured in Microns or Mils. Measurement determined by the number between the last tooth coated and the following tooth which is free of coating. Measuring wet coating (2) Wet Film Wheel - ANSWER - Method to measure wet coating using two outer wheels fixed to a central spindle wheel. Thickness is measured by rolling the wheel on the maximum scale towards accurately ground zero. When rolling the wheel on the coated board, the central wheel will touch the coating. The first point of contact on the central wheel determines the wet film thickness. Measling - ANSWER - Internal condition occurring in laminated base material in which th e glass fibers are separated from the resin at the weave intersection. This condition manifests itself in the form of discrete white spots or crosses below the surface of the base material, and is usually related to THERMALLY INDUCED STRESS. Crazing - ANS WER - Internal condition occurring in the laminated base material in which the glass fibers are separated from the resin at the weave intersections. This condition manifests itself in the form of CONNECTED white spots or crosses below the surface of the bas e material and usually related to MECHANICALLY INDUCED STRESS. Blistering - ANSWER - Delamination in the form of a localized swelling and separation between any of the layers of a lamination base material, or between base material and conductive foil or pr otective coating. Delamination - ANSWER - Separation between plies within base material, between a base material and a conductive foil or any other planar separation within a printed board. Weave Texture - ANSWER - Surface condition of a base material in which a weave pattern of glass cloth is apparent although the unbroken fibers are completely covered with resin. Weave Exposure - ANSWER - Surface condition of a base material in which the unbroken fibers of woven glass cloth are NOT completely covered by r esin. Haloing - ANSWER - condition existing in the base material in the form of a light area around holes or other machined areas on or below the surface of the base material. Mechanically induced fracturing or delamination on or below the surface of the b ase material; a Light area around the holes, other machined areas or both. (a light ring around a hole on a circuit board) FOD (Foreign Object Debris) - ANSWER - A generic term for a substance, debris, particulate matter or article alien to the assembly or system. ex: wire and lead clippings, hair, dust, non -ESD safe objects. Solder Mask Coating - ANSWER - Heat -resisting coating material applied to selected areas to prevent the deposition of solder upon those areas during subsequent soldering. Solder Mask m aterial may be applied as a liquid or a dry film. (ex: pink masking) Conformal Coating - ANSWER - Provides a barrier layer to the surface of an electronic assembly to provide protection against the end use environment. -distribution depends partly on the m ethod of application and may affect visual appearance and corner coverage. Dipping - ANSWER - May have a drip line or localized build -up on the edge of the board. This build -up may contain small amount of bubbles but it will not affect the functionality or reliability of the coating.
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