A step-by-step approach to maintaining your conformal coating equipment for consistent quality, extended component life, and prevention of cross-contamination.

In PCB protection, conformal coating is the final and critical line of defense against moisture, dust, chemicals, and thermal stress. But much like the boards they protect, the machines that apply these coatings require their own form of protection: regular and thorough cleaning.

To maintain consistency, the often-overlooked activity of regular cleaning and flushing of selective coating equipment is essential. So cleaning your conformal coating machine, focusing on the critical areas: valves, cleaning materials, and the step-by-step process.

Part 1: Why Clean and Flush? The Benefits of Regular Maintenance

Before diving into the "how," it's important to understand the "why." Regular cleaning and flushing of your conformal coating system delivers four key benefits :

⚠️ CRITICAL NOTE ON SILICONES: When a silicone coating chemistry is used, never use the same fluid lines, valves, or pressure pot when converting to other chemistries such as acrylics, urethanes, or synthetic rubbers. Silicone contamination is extremely difficult to remove and will cause severe adhesion failures (fisheyes and dewetting) in subsequent coatings .

Part 2: When to Clean – Timing Your Maintenance

Knowing when to clean is just as important as knowing how. Here are the specific circumstances that call for a thorough cleaning and flushing of your selective coating equipment :

Part 3: Cleaning Materials – Choosing the Right Solvent

Using the correct cleaning material is crucial for effective maintenance without damaging equipment. Here are the key considerations:

1. Use Manufacturer-Recommended Thinners, Not Strippers

Important: Always use thinners provided by your coating manufacturer, not stripping agents. Strippers are formulated for removing cured coatings from PCBs and are too aggressive for cleaning equipment .

Compatible solvents typically include:

 MEK (Methyl Ethyl Ketone)

 Xylene

 Commercial thinners matched to your specific coating chemistry

2. Commercial Cleaning Products

Several specialized cleaning products are available for conformal coating equipment:

 3. The Fluorescence Test

Many conformal coatings contain fluorescing agents to aid in inspection under UV light. This feature can also be used to verify cleaning effectiveness:

 Turn on the machine's blacklight (UV light)

 Flush with solvent until the flushed material stops fluorescing blue

 If the coating does not contain fluorescing agents, flush until the coating appears to be eliminated

Part 4: Cleaning Valves – The Heart of the Machine

Valves are the most critical components requiring careful attention during cleaning. Here are specific considerations:

Valve-Specific Precautions

 Needle Valve Care: When cleaning, do not clean or mix the needle valve with other devices to prevent damaging the needle tip. Never poke other objects with the needle valve .

 Air Cap Removal: Before flushing, remove the air cap (if applicable) of the valve and back off the micrometer (if applicable) to allow for more needle travel .

Cleaning Frequency for Valves

 24-Hour Rule: If the spray gun is not used for more than 24 hours, it must be cleaned .

 Daily Cleaning: After using coating every day, always wash the paint inlet pipe with thinner. Remove the paint inlet pipe and spray an appropriate amount of thinner at least 10 times .

 Soaking and Scrubbing: Soaking and scrubbing methods improve reactivity and cleaning effectiveness .

Part 5: The Step-by-Step Cleaning and Flushing Process

Here is the complete procedure for cleaning and flushing your conformal coating equipment. Note: Consult your equipment manufacturer for machine-specific details before attempting .

Step 1: Preparation

 Remove excess coating from the reservoir or pressure pot

 Remove the air cap (if applicable) and back off the micrometer to permit more needle travel

Step 2: Initial Flush

 Flush the coating from the coating reservoir, fluid lines, and valve until no coating comes out

 Use a compatible solvent/thinner (MEK, xylene, or commercial thinner recommended by your coating manufacturer)

Step 3: Solvent Flush with Fluorescence Check

 Add a compatible solvent/thinner to the fluid reservoir

 Turn on the machine's blacklight

 Flush until the solvent/thinner stops fluorescing blue (if coating contains fluorescing agents)

 Otherwise, flush until coating appears to be eliminated

Step 4: Final Flush and Preparation for Restart

 Add a small amount of additional thinner

 Flush just until the fluid becomes spray (the transition from stream to spray indicates flushing fluid is running out)

 Stop immediately—this leaves a very small amount of solvent/thinner in the fluid lines/valve, which is correct

Step 5: Restart Procedure

 Flush the remaining solvent from the fluid reservoir, fluid lines, and valves

 The machine and valve are now ready to be filled with fresh coating

Part 6: Pre-Cleaning PCBs – A Critical Prerequisite

While cleaning the machine is essential, don't overlook the importance of cleaning the PCBs themselves before coating. Contamination on boards can cause coating defects regardless of how clean your machine is .

Common Contaminants to Remove

The "No-Clean" Flux Myth

"No-clean" fluxes are often left on boards even when coating will be applied. However, the benign glassy layer that encapsulates ionic residues in no-clean fluxes can be disrupted by the aggressive solvents in conformal coatings (like acetone or xylene). This can release ionic contamination underneath the coating or distribute it within the resin, impacting the integrity of the cured coating .

Recommendation: Cleaning before coating is strongly recommended, even with no-clean flux .

Cleaning Methods for PCBs

Method	Description	Best For
Manual Cleaning	Aerosol or pump sprays, solvents in pan/tray; agitation with brush, swab, or wipe.	Low volume, prototyping, repair
Ultrasonic	Sound waves create bubbles that implode on surface to break up residues.	High-volume, thorough cleaning
Vapor Degreasing	Cleaning in solvent vapor phase or submerged sump, often with ultrasonic action.	Critical applications, complex geometries
Batch/Inline Systems	Spray equipment with water-based cleaners that wash, rinse, and dry.	Nachrichten Haus > Neuigkeiten > Firmennachrichten über-The Essential Guide to Cleaning Conformal Coating Machines: Valves, Processes, and Materials Ereignisse Neuigkeiten Fälle The Essential Guide to Cleaning Conformal Coating Machines: Valves, Processes, and Materials 2026-03-20 A step-by-step approach to maintaining your conformal coating equipment for consistent quality, extended component life, and prevention of cross-contamination.   In PCB protection, conformal coating is the final and critical line of defense against moisture, dust, chemicals, and thermal stress. But much like the boards they protect, the machines that apply these coatings require their own form of protection: regular and thorough cleaning.   To maintain consistency, the often-overlooked activity of regular cleaning and flushing of selective coating equipment is essential. So cleaning your conformal coating machine, focusing on the critical areas: valves, cleaning materials, and the step-by-step process.     Part 1: Why Clean and Flush? The Benefits of Regular Maintenance   Before diving into the "how," it's important to understand the "why." Regular cleaning and flushing of your conformal coating system delivers four key benefits :   Benefit Description Extended Component Life Improves the working life of valves, nozzles, spray heads, and feed/return lines. Process Consistency Minimizes inconsistencies caused by clogs or buildups that affect flow rates and spray patterns. Quality Improvement Ensures reliable and consistent material usage, application thickness, and coating pattern width and edge definition. Contamination Prevention Prevents cross-contamination when switching between incompatible coating chemistries.     ⚠️ CRITICAL NOTE ON SILICONES: When a silicone coating chemistry is used, never use the same fluid lines, valves, or pressure pot when converting to other chemistries such as acrylics, urethanes, or synthetic rubbers. Silicone contamination is extremely difficult to remove and will cause severe adhesion failures (fisheyes and dewetting) in subsequent coatings .     Part 2: When to Clean – Timing Your Maintenance   Knowing when to clean is just as important as knowing how. Here are the specific circumstances that call for a thorough cleaning and flushing of your selective coating equipment :   Cleaning Trigger Timing / Condition Chemistry Changeovers When switching between different coating types (e.g., acrylic to urethane, synthetic rubber to acrylic). Extended Shutdowns After shutdowns of 48 hours or more for acrylics, synthetic rubbers, and non-moisture-sensitive materials. Moisture-Sensitive Materials At the end of every production day for moisture-sensitive materials, including most silicones and many urethanes. Performance Issues Any time inconsistent spray patterns or irregular flow rates are observed.     Part 3: Cleaning Materials – Choosing the Right Solvent   Using the correct cleaning material is crucial for effective maintenance without damaging equipment. Here are the key considerations:   1. Use Manufacturer-Recommended Thinners, Not Strippers   Important: Always use thinners provided by your coating manufacturer, not stripping agents. Strippers are formulated for removing cured coatings from PCBs and are too aggressive for cleaning equipment .   Compatible solvents typically include:  MEK (Methyl Ethyl Ketone)  Xylene  Commercial thinners matched to your specific coating chemistry   2. Commercial Cleaning Products   Several specialized cleaning products are available for conformal coating equipment: Product Description Application Electrolube OP9004 Non-flammable solvent blend designed to swell and soften cured epoxy, polyurethane, and chemically resistant conformal coatings. Suitable for cleaning machines by wiping; slower evaporation rate for effective cleaning. Dow Corning OS-120 Low-VOC cleaning fluid specifically for removing residual silicone from dispensing equipment. Ideal for silicone coating applications where low-VOC compliance is required. Electrolube ULS400D Fast-drying solvent for quick and efficient cleaning of electrical equipment; removes flux residues and acrylic conformal coatings. Suitable for PCB cleaning; contains flammable solvent so avoid use on live equipment. Surclean SC 400 Blend of glycol ethers and hydrocarbons for fast removal of uncured residues. While designed for stencils, similar principles apply; ultra low-VOC and biodegradable.  3. The Fluorescence Test   Many conformal coatings contain fluorescing agents to aid in inspection under UV light. This feature can also be used to verify cleaning effectiveness:    Turn on the machine's blacklight (UV light)  Flush with solvent until the flushed material stops fluorescing blue  If the coating does not contain fluorescing agents, flush until the coating appears to be eliminated     Part 4: Cleaning Valves – The Heart of the Machine   Valves are the most critical components requiring careful attention during cleaning. Here are specific considerations:   Valve-Specific Precautions    Needle Valve Care: When cleaning, do not clean or mix the needle valve with other devices to prevent damaging the needle tip. Never poke other objects with the needle valve .  Air Cap Removal: Before flushing, remove the air cap (if applicable) of the valve and back off the micrometer (if applicable) to allow for more needle travel .   Cleaning Frequency for Valves    24-Hour Rule: If the spray gun is not used for more than 24 hours, it must be cleaned .  Daily Cleaning: After using coating every day, always wash the paint inlet pipe with thinner. Remove the paint inlet pipe and spray an appropriate amount of thinner at least 10 times .  Soaking and Scrubbing: Soaking and scrubbing methods improve reactivity and cleaning effectiveness .     Part 5: The Step-by-Step Cleaning and Flushing Process   Here is the complete procedure for cleaning and flushing your conformal coating equipment. Note: Consult your equipment manufacturer for machine-specific details before attempting .   Step 1: Preparation  Remove excess coating from the reservoir or pressure pot  Remove the air cap (if applicable) and back off the micrometer to permit more needle travel   Step 2: Initial Flush  Flush the coating from the coating reservoir, fluid lines, and valve until no coating comes out  Use a compatible solvent/thinner (MEK, xylene, or commercial thinner recommended by your coating manufacturer)   Step 3: Solvent Flush with Fluorescence Check  Add a compatible solvent/thinner to the fluid reservoir  Turn on the machine's blacklight  Flush until the solvent/thinner stops fluorescing blue (if coating contains fluorescing agents)  Otherwise, flush until coating appears to be eliminated   Step 4: Final Flush and Preparation for Restart  Add a small amount of additional thinner  Flush just until the fluid becomes spray (the transition from stream to spray indicates flushing fluid is running out)  Stop immediately—this leaves a very small amount of solvent/thinner in the fluid lines/valve, which is correct   Step 5: Restart Procedure  Flush the remaining solvent from the fluid reservoir, fluid lines, and valves  The machine and valve are now ready to be filled with fresh coating     Part 6: Pre-Cleaning PCBs – A Critical Prerequisite   While cleaning the machine is essential, don't overlook the importance of cleaning the PCBs themselves before coating. Contamination on boards can cause coating defects regardless of how clean your machine is .   Common Contaminants to Remove   Contaminant Type Source Residual etchants Original bare board fabrication Dust Bare board drilling, cutting, and scoring Fingerprints and skin oils Board handling Silicone and other oils Migrating from other processes Flux residues Soldering process (most common concern)     The "No-Clean" Flux Myth   "No-clean" fluxes are often left on boards even when coating will be applied. However, the benign glassy layer that encapsulates ionic residues in no-clean fluxes can be disrupted by the aggressive solvents in conformal coatings (like acetone or xylene). This can release ionic contamination underneath the coating or distribute it within the resin, impacting the integrity of the cured coating .   Recommendation: Cleaning before coating is strongly recommended, even with no-clean flux .   Cleaning Methods for PCBs Method Description Best For Manual Cleaning Aerosol or pump sprays, solvents in pan/tray; agitation with brush, swab, or wipe. Low volume, prototyping, repair Ultrasonic Sound waves create bubbles that implode on surface to break up residues. High-volume, thorough cleaning Vapor Degreasing Cleaning in solvent vapor phase or submerged sump, often with ultrasonic action. Critical applications, complex geometries Batch/Inline Systems Spray equipment with water-based cleaners that wash, rinse, and dry. +86 16620793861 Schnelle Verbindung Haus ÜBER US produits Anwendung Neuigkeiten Fälle Treten Sie mit uns in Verbindung Schnelle Kontaktaufnahme Adresse Gebäude Nr. 142 / B311, Songyu Road, Gemeinde Hongxing, Straße Songgang, Bezirk Baoan, Shenzhen, China. Telefon +86-16620793861 E-Mail alina@hxt-smt.com +86 16620793861 Unser Newsletter Abonnieren Sie unseren Newsletter für Rabatte und mehr. e-mail senden Privacy policy |  Sitemap  | Gute Qualität Chinas Auswahl- und Platzmaschine Lieferant. Copyright-© 2025-2026 Shenzhen Hongxinteng Technology Co., Ltd. . Alle Rechte vorbehalten.