LOCTITE 3131
Harmonization Code : 3907.30.00.40 | Epoxy Mold Compounds containing by weight more than 70 % silicon dioxide
Main features
- UV/Heat Dual-Cure Assembly
- One-Second UV Tack-Free Time
- Image-Sensor Module Bonding
Product Description
LOCTITE 3131 is a one-part amber epoxy/acrylate adhesive with UV and heat dual-cure processing for temperature-sensitive electronic components. The recommended UV step uses 220 to 260 nm light at 100 mW/cm^2 and reaches tack-free condition in one second, followed by a thermal schedule of 30 minutes at 60 deg C, 25 minutes at 70 deg C, or 20 minutes at 80 deg C. The uncured material has 14,000 mPa s viscosity and a pot life greater than 14 days at 25 deg C. The cured material reaches Shore D 88 and 1.8 N/mm^2 lap shear strength on polycarbonate under the specified cure conditions. Applications include image-sensor module assemblies.
Key features
- UV and heat dual cure: Maximum performance uses UV exposure followed by thermal cure for temperature-sensitive electronic components.
- One-second UV tack-free: A medium-pressure mercury lamp at 220 to 260 nm and 100 mW/cm^2 reaches tack-free condition in one second.
- Flexible thermal schedule: Recommended heat-cure options are 30 minutes at 60 deg C, 25 minutes at 70 deg C, or 20 minutes at 80 deg C.
Applications
Applications include image-sensor module assemblies and other temperature-sensitive electronic component assemblies within the stated UV-and-heat cure process.
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Appearance
Amber
Appearance at room temperature.
Pot Life
>14 days
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.
Specific Gravity
1.23
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.
Physical Properties
Thixotropic index
1.6
Thixotropic Index is a ratio of a material s viscosity at two different speeds in Ambient temperature, generally different by a factor of ten.
A thixotropic material s viscosity will decrease as agitation or pressure is increased. It indicates the capability of a material to hold its shape. Mayonnaise is a great example of this. It holds its shape very well, but when a shear stress is applied, the material easily spreads.
It helps in choosing a material in accordance to the application, dispense method and viscosity of a material.
Viscosity
14,000 mPa.s
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
Thermal Properties
Glass Transition Temperature (Tg)
85 °C
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.
Other Properties
Storage Temperature
2 to 8 °C
Additional Information
Technical properties
As-supplied / before-processing properties
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Viscosity | 14,000 | mPa s (cP) | Haake PK-100; cone PK1; 2 deg; at 25 deg C |
| Yield point | 9,013 | mPa s (cP) | At 25 deg C |
| Thixotropic index | 1.6 | 2/20 s^-1 | |
| Specific gravity | 1.23 | Uncured material | |
| Pot life | >14 | days | At 25 deg C |
Technical properties
After-processing / final-state properties
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Hardness | 88 | Shore D | ASTM D2240; sample cured 5 s at 100 mW/cm^2 plus 30 min at 80 deg C |
| Glass transition temperature | 85 | deg C | TMA; sample cured 5 s at 100 mW/cm^2 plus 30 min at 80 deg C |
| CTE alpha 1 | 49 x 10^-6 | cm/cm/deg C | Sample cured 5 s at 100 mW/cm^2 plus 30 min at 80 deg C |
| CTE alpha 2 | 175 x 10^-6 | cm/cm/deg C | Sample cured 5 s at 100 mW/cm^2 plus 30 min at 80 deg C |
| Volume shrinkage on cure | 2.4 | % | Sample cured 5 s at 100 mW/cm^2 plus 30 min at 80 deg C |
| Lap shear strength | 1.8 | N/mm^2 | Polycarbonate; sample cured 2 s at 100 mW/cm^2 plus 30 min at 80 deg C |
