LOCTITE 3549
Harmonization Code : 3506.91.90.99 | Prepared glues and other prepared adhesives, not elsewhere specified or included; products suitable for use as glues or adhesives, put up for retail sale as glues or adhesives, not exceeding a net weight of 1 kg ; Adhesives based on polymers of headings 3901 to 3913 or on rubber; Other ; Other
Main features
- Reworkable Underfill Material
- Fast Flow Underfill Material
- Low Temperature Cure
Product Description
LOCTITE® 3549 is a one-component, heat-curing epoxy underfill specifically developed to protect solder joints in ball grid array (BGA) and chip-scale package (CSP) assemblies. The black, reworkable formulation flows rapidly beneath components to reduce stress concentrations and improve reliability during thermal cycling and mechanical shock events. Designed for low-temperature cure processing, LOCTITE 3549 enhances drop-test performance while providing excellent adhesion to both rigid and flexible substrates. The material is particularly suited for electronic packaging applications where long-term solder joint protection and assembly durability are critical.
Key Features & Benefits
- One-component, heat-curing epoxy underfill.
- Reworkable formulation for easier component replacement.
- Fast-flow characteristics support efficient underfill processing.
- Low-temperature cure capability for sensitive electronic assemblies.
- Excellent adhesion to rigid and flexible substrates.
- Provides outstanding protection of solder joints against induced stresses.
- Improves drop-test and thermal-cycle reliability of BGA and CSP devices.
Recommended Applications
- BGA underfill applications.
- CSP device protection and reinforcement.
- Electronic packaging and assembly operations.
- Solder-joint reliability enhancement.
- Assemblies requiring reworkable underfill materials.
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Thermal Properties
Physical Properties
Additional Information
As-Supplied / Before-Processing Properties
| Property | Value | Unit | Condition |
|---|---|---|---|
| Technology | Epoxy | — | One-component underfill |
| Appearance | Black | — | Liquid |
| Density | 1.3 | g/cm³ | 25°C |
| Viscosity (Haake PK100) | 2,350 | mPa·s | 36 s⁻¹, 25°C |
| Viscosity (Cone & Plate) | 2,100 | mPa·s | Spindle 52, 50 rpm |
| Filler Content | 18 | % | Typical |
| Pot Life | 14 | days | 25°C, time to double viscosity |
| Shelf Life | 365 | days | -25 to -15°C storage |
After-Processing / Final-State Properties
| Property | Value | Unit | Condition / Method |
|---|---|---|---|
| Coefficient of Thermal Expansion (Below Tg) | 55 × 10⁻⁶ | K⁻¹ | ISO 11359-2 |
| Coefficient of Thermal Expansion (Above Tg) | 177 × 10⁻⁶ | K⁻¹ | ISO 11359-2 |
| Glass Transition Temperature (Tg) | 38 | °C | TMA, -50°C to 300°C |
| Storage Modulus | 2,000 | N/mm² | DMA, 22°C to 300°C |
| Volume Resistivity | 8.1 × 10¹⁵ | Ω·cm | IEC 60093 |
| Surface Resistivity | 0.2 × 10¹⁵ | Ω | IEC 60093 |
| Recommended Cure | 5 min @ 120°C | — | Standard cure schedule |
| Exotherm Onset | 100 - 115 | °C | DSC analysis |
