LINQBOND UF3802 | Underfill


Main features
  • High Tg
  • low viscosity
  • one-component

Product Description

LINQBOND UF3802 is a one-component epoxy adhesive developed for electronic device bonding. It is easy to operate and suitable for various applications, such as casting, sealing, and encapsulation of electronic components. This product cures quickly at high temperatures, reducing working time and increasing efficiency.

LINQBOND UF3802 forms tough, strong structural bonds that provide excellent shear, peel, and impact strength. The product's durability is exceptional, capable of passing numerous environmental tests. For under-filling CSP and BGA, it helps buffer the dilational shrinkage stress of tin balls and mitigates shear stress caused by counteracting forces during drop tests.

 
Product Family
UF3802  
50ml syringe 30ml syringe 10ml syringe

Catalog Product

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Packaging
TDS, SDS & Technical documents

Technical Specifications

General Properties
Pot Life
Pot Life
Pot life is the amount of time it takes for the viscosity of a material to double (or quadruple for lower viscosity materials) in room temperature after a material is mixed.

It is closely related to work life but it is not application dependent, less precise and more of a general indication of how fast a system is going to cure.
 72 hours
Specific Gravity
Specific Gravity
Specific gravity (SG) is the ratio of the density of a substance to the density of a reference substance; equivalently, it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume.

For liquids, the reference substance is almost always water (1), while for gases, it is air (1.18) at room temperature. Specific gravity is unitless.
 1.19
Work life @25°C
Work life @25°C
Work life is the amount of time we have to work with a material until it is no longer able to be easily worked and applied on a substrate.

It is based on the change in viscosity and it can rely on the application requirements.
 72 hours
Shelf Life
Shelf Life
Shelf life is the amount of time after manufacturing that a product is guaranteed to retain its properties.

It differs vastly per product and it is based on temperature and storage conditions.

The properties can be guaranteed for the temperature and time range indicated on the TDS since those are the ones tested to be the best for the product.
Shelf Life @ -20°C 273 days
Physical Properties
Viscosity
Viscosity
Viscosity is a measurement of a fluid’s resistance to flow.

Viscosity is commonly measured in centiPoise (cP). One cP is defined as
the viscosity of water and all other viscosities are derived from this base. MPa is another common unit with a 1:1 conversion to cP.

A product like honey would have a much higher viscosity -around 10,000 cPs-
compared to water. As a result, honey would flow much slower out of a tipped glass than
water would.

The viscosity of a material can be decreased with an increase in temperature in
order to better suit an application
 290 mPa.s
Thermal Properties
Coefficient of Thermal Expansion (CTE)
Coefficient of Thermal Expansion (CTE)
CTE (Coefficient of thermal expansion) is a material property that is indicative of the extent to which a material expands with a change in temperature. This can be a change in length, area or volume, depending on the material.

Knowing the CTE of the layers is helpful in analyzing stresses that might occur when a
system consists of an adhesive plus some other solid component.
Coefficient of Thermal Expansion (CTE), α1
Coefficient of Thermal Expansion (CTE), α1
CTE α1 (alpha 1) is the slope of the Coefficient of thermal expansion in a temperature range below the Glass transition temperature (Tg).

It explains how much a material will expand until it reaches Tg.
 88 ppm/°C
Coefficient of Thermal Expansion (CTE), α2
Coefficient of Thermal Expansion (CTE), α2
CTE α2 (alpha 2) is the slope of the Coefficient of thermal expansion in a temperature range above the Glass transition temperature (Tg).

It explains the extent to which a material will expand after it passes Tg.
 252 ppm/°C
Glass Transition Temperature (Tg)
Glass Transition Temperature (Tg)
The glass transition temperature for organic adhesives is a temperature region where the polymers change from glassy and brittle to soft and rubbery. Increasing the temperature further continues the softening process as the viscosity drops too. Temperatures between the glass transition temperature and below the decomposition point of the adhesive are the best region for bonding.

The glass-transition temperature Tg of a material characterizes the range of temperatures over which this glass transition occurs.
 113 °C

Additional Information

Instructions for Use:

  1. Before use, thaw the product to reach room temperature for 1–2 hours. The syringe should be placed vertically while thawing. Keep the container airtight until room temperature is reached.

  2. Ensure the surface to be bonded is clean and free of contaminants like dirt, grease, or mold release agents. A simple solvent wipe is often sufficient.

  3. Cure time may vary based on the actual part geometry, material volume, and equipment. It is recommended that the test be done on actual parts and equipment.

  4. For large-scale applications, consider a staged curing process: start with a lower temperature pre-cure, followed by a full cure at a higher temperature to manage heat release effectively.

  5. Cool down gradually after curing to minimize thermal stress.

  6. The epoxy cannot be refrozen once exposed to room temperature.

Rework Process:

  1. Component Removal. Component solder joints must be heated above their reflow temperature (260°C to 280°C). At this temperature, the undefill will be soft and easy to remove. Component may then be pulled or removed by twisting or with a use of a vacuum pick-up nozzle.

  2. Site Preparation. After component removal, cleaning of residues may be done by the following methods

    • Scraping. Heat the site to 250°C to 300°C and scrape off the underfill carefully avoiding damage of pads on the substrate. Alternatively, heating can also be done from the bottom of the substrate.

    • Rotating Brush. Apply sufficient amount of pressure onto the brush to clean the residues. Care should be taken to avoid damage to substrate.

  3. Component Replacement. Isopropanol or a flux pen may be used to ensure no residue remains on the circuit board after cleaning. Brush solder paste or flux on the board and align the new component using a vacuum and reflow using hot air. Underfill will likewise be applied followed by cure step.

Storage and Handling

Store and transport below -5°C temperature. Keep away from moisture and heat sources. It is strictly forbidden to store in outdoor environments.