IPC-A-610 Test Study Guide with Complete Solutions

IPC-A-610 Test Study Guide with Complete Solutions 3 types of Conformal Coating: Acrylic Resin (AR) - Answer-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) - Answer-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) - Answer-This type of coating is known for its EXCELLENT moisture and chemical resistance. It is also very abrasion resistant. Combining those factors with its SOLVENT RESISTANCE results in a conformal coating GRACEAMELIA 2024/2025 ACADEMIC YEAR ©2024. ALL RIGHTS RESERVED. FIRST PUBLISH OCTOBER, 2024 Page 2/10 that is very difficult to remove. Like SR, full removal generally requires special solvents, long soak time, and agitation with a brush. This is common in aerospace application. ex: Conathane 5 Coating application methods: Manual Spraying - Answer-Aerosol can or handheld spray gun. Time consuming method of coating for a small quantity of boards. Lots of masking beforehand. Quality and consistency of outcome are operator- dependent. 5 Coating application methods: Automated spraying - Answer-Programmed spray system that moves the board on a CONVEYOR under an alternative spray head that applies a conformal coating. 5 Coating application methods: Selective coating - Answer-An automated conformal coating process that uses PROGRAMMABLE ROBOTIC SPRAY NOZZLES to apply the coating to very specific areas on the circuit board. May eliminate the need for masking using the program. The UV lamp in machine helps cure the coating right after it is sprayed. 5 Coating application methods: Dipping - Answer-The circuit board is first immersed, Then withdrawn from the conformal coating solution. Immersion speed, withdrawn speed, Immersion time, and Viscosity determine the resulting film formation. Common for high volume processing. Masking may increase. This method is good to coat both Front and Back of the board. 5 Coating application methods: Brushing - Answer-Simple application method used mainly in repair and rework. Conformal Coating is applied with a BRUSH to specific areas on the board. GRACEAMELIA 2024/2025 ACADEMIC YEAR ©2024. ALL RIGHTS RESERVED. FIRST PUBLISH OCTOBER, 2024 Page 3/10 Low-cost method but requires lots of manual labor and is highly variable depending on operator proficiency and consistency. This is the best for a small batch or a single board. 1. Solvent Removal 2. Peeling 3. Microblasting: using a concentrated mix of soft abrasive and compressed air to abrade the coating. 4. Grinding/Scaping - Answer-What are the Conformal Coating Removal Methods by IPC? (4) (6) Most Common Coating Defects and causes: Capillary Flow - Answer-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 - Answer-Visual cracks and creases on components. Causes: -coating is too thick - thermal shock GRACEAMELIA 2024/2025 ACADEMIC YEAR ©2024. ALL RIGHTS RESERVED. FIRST PUBLISH OCTOBER, 2024 Page 4/10 - coating cured too quickly (6) Most Common Coating Defects and causes: Dewetting - Answer-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: Delamination - Answer-When coating has lifted up and awa