(6) Most Common Coating Defects and causes:
Capillary Flow Correct Ans-occurs when coating migrates from one area of a board to
another, leaving behind an inconsistent, uneven finish on the surface.
Causes: -application of too much coating
- coating with low viscosity or high surface tension.
- low surface energy of component being coated.
(6) Most Common Coating Defects and causes:
Cracking and Ripples Correct Ans-Visual cracks and creases on components.
Causes: -coating is too thick
- thermal shock
- coating cured too quickly
(6) Most Common Coating Defects and causes:
Dewetting Correct Ans-Coating will not evenly coat the surface to which its applied.
Causes: - uneven coating application.
- improper mixture of two- part material.
- Residue on coating surface.
- Surface tension and surface energy.
(6) Most Common Coating Defects and causes:
, IPC-A-610 Test with Complete Solutions
Delamination Correct Ans-When coating has lifted up and away from the board. This
hinders protection because the area below the coating is left exposed. (Ex:Ripping off more
coating after demasking and pulling off too much coating around the area.
Causes:
-too thick of coating
- coating not adhering to previous coating layer.
-contamination of surface of the board.
3 types of Conformal Coating: Acrylic Resin (AR) Correct Ans-This type of coating provides
FAIR elasticity and general protection. It has high dielectric strength, and fair moisture and
abrasion resistance. This coating is different from others because its facility for removal. This
type are EASILY and quickly removed by a variety of solvents, often without requiring
agitation. This makes rework and field repair very practical and economical. This type doesn't
protect against solvents and solvent vapors.
3 types of Conformal Coating: Silicone Resin (SR) Correct Ans-This type of coating provides
EXCELLENT protection in a very wide temperature range. This coating provides good chemical
resistance, moisture, and salt spray resistance, and is very flexible. This type is NOT abrasion
resistant because of its rubbery nature, but this property does make it resilient against
vibrational stresses. Commonly used in high-humidity environments. Removal can be
CHALLENGING. requiring specialized solvents, long soak time, and agitation from a brush.
3 types of Conformal Coating: Urethane (Polyurethane) Resin (UR) Correct Ans-This type of
coating is known for its EXCELLENT moisture and chemical resistance. It is also very abrasion