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LPI Solder Mask Touch Up Pen TDS


FLS Discount Supplies                        TDS # LPI       Version 9               Revised 1-15-19

Technical Data Sheet

       TDS# LPI


FLS LPI Liquid Photo imageable Solder Mask Touch Up Paint Ink Pens. Technical pen for printed circuit board, and bare board mask retouching. Ideal for protecting and insulating circuit board traces, components, and other delicate electronics. This highly effective coating provides excellent protection against shorts, moisture, abrasion, fungus, and other environmental hazards. Allows for easy repair of solder mask in prototype, manufacture and repair of circuit boards.

Simple to use, single component system

ü  Hard, durable coating

ü  High dielectric strength

ü  Helps prevent arcing and shorts

ü  Offers Excellent Coverage

ü  Chip Resistance

ü  Color Retention

ü  Peel Resistant

ü  Protects against moisture damage

ü  Helps prevent static discharge problems on sensitive components


LPI Mask Touch Up Pen may be used for electronics applications in:

ü  Circuit Board Manufacturing

ü  Data Communications

ü  Aerospace

ü  Instrumentation

ü  Controls

ü  General Maintenance and Repair


Pen has excellent resistance to water based cleaners and limited resistance to aggressive organic solvents such as acetone. The chemical resistance of LPI can be enhanced by heat curing.


LPI Pen material is generally compatible with materials used in printed circuit board fabrication. As with any adhesive/sealant, compatibility with substrate should be determined on a noncritical area prior to use.


Cleaning Application Surface: For best adhesion, clean the board with an Electro-Wash cleaner in order to remove any surface contamination which may prevent adequate material contact.

Usage Conditions:

Apply only when air and surface temperatures are above 50°F (10°C) and humidity is below 85% to ensure proper drying. Do not apply to surfaces that will exceed 200°F (93°C). Do not use on galvanized steel.


1) Shake pen vigorously until you hear the sound of clicking against the pen sides to ensure pigment is re-dispersed. This must be done before each use.

2) Remove the pen cap.

3) Always use a piece of scratch paper to test line thickness when first using the pen.

4) Press the tip down on the test surface while squeezing the flat sides of the pen together and hold until you see ink forming. If the pen ink is not coming out shake the pen more vigorously with tip end down to create flow into the tip. This process will have to be repeated several times depending on the color pen. The white and black ink tend to flow more freely. When you see the ink starting to come out of the pen, draw a line until ink comes out in an even flow to the correct thickness desired. This must be done each time the pen is used.

Note: The ink fills entire tube body of the Pen. Pen must be vigorously shaken before each use. Squeezing the pen body while pressing the tip down on the surface will allow the ink to flow.


Thinning:The mask material has been optimized for the LPI Pen and thinning is not normally necessary. However, acetone may be added with thorough mixing to make slight adjustments for ease of application.  

  • Warning- DO NOT thin with gasoline, lacquer thinner, turpentine, ect.


1)       Air dry (may take 2-48 hours depending on environment)

       Air Dry Times at 77°F (25°C) and 50% relative humidity. Air Dry to touch is approximately 2-  

       4 hours in the right conditions. Air Dry to handle is approximately 5 to 9 hours and after 24

       hours dry enough to recoat if necessary when air dried.

2)       (or) Put a fan in area on low at least 4 feet away from ink, or on medium at least 5-6 feet away from ink to increase air drying times.

3)       We have been notified by customers who use this product that a heat cure of 5 - 10 minutes at 200°F (93 °C) works as well for more demanding applications and for enhancing the chemical resistance. We are not allowed to recommend this drying option due to msds information even though no problems have arisen when dried this way in the past. We accept no responsibility for safety and for product if a bake cycle is used to dry. LPI does have a dry heat resistance of 200°F (93°C).

  • Apply only when air and surface temperatures are above 50°F (10°C) and humidity is below 85% to ensure proper drying


Clean-UP:The mask material may be cleaned off the pen parts or other items by using Mineral Spirits only.  

Storage of Pen: Store pens in a cool dry environment, in a zip lock air tight baggie, with tips facing upward.

  •     Product shelf life is approximately 3-6 months if stored with tip facing up and in a cool dry place, and can be prolonged if stored in a zip lock bag. Some colors are known to last much longer. Please remember to rotate your stock.


Important Safety Information:

Flash Point: 104°F (Setaflash)

Dry Heat Resistance 200°F (93°C)

Shelf Life 3-4 months if stored correctly


Work/Hygienic Practices: Have good ventilation while using product. Rubber, latex, or other chemically resistant gloves can be used when handling this material. Wash hands thoroughly with soap and water before eating, drinking or smoking after pen use if ink gets on hands.

For additional information, see MSDS

The technical data and suggestions for use contained herein are correct to the best of our knowledge, and offered in good faith. The statements of this literature do not constitute a warranty, express, or implied, as to the performance of these products. As conditions and use of our materials are beyond our control, we can guarantee these products only to conform to our standards of quality, and our liability, if any, will be limited to replacement of defective materials. All technical information is subject to change without notice.