LINQBOND UF3501R | Reworkable Underfill

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 to test 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 effectively manage heat release.

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. At this temperature, the underfill will be soft and easy to remove. The component may then be pulled or removed by twisting or with a use of a vacuum pick-up nozzle.

2. Site Preparation. Cleaning of residues after component removal  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.

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

4. 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 the 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.