COOLTHERM ME-531
Harmonization Code : 3910.00.00.90 | Silicones in Primary Forms; Others
Main features
- 4,000 cP Jettable Capillary Underfill
- 140 deg C Glass Transition
- 30-Minute 150 deg C Cure
Product Description
CoolTherm® ME-531 Underfill Encapsulant is a high-purity, semiconductor-grade, one-part epoxy underfill developed for flip-chip device encapsulation and higher-temperature package requirements. The black, low-viscosity liquid has a typical 4,000 cP viscosity at 25°C, 16-hour working life at 25°C, and six-minute gel time at 150°C. It supports capillary corner-dot application and high-speed jetting. For the documented capillary process, preheat the substrate to 100°C and cure for 30 minutes at 150°C or 15 minutes at 165°C. Typical cured properties include 140°C Tg by TMA, 21 ppm/°C α1 CTE, 0.5 W/m·K thermal conductivity, and 1 × 1015 ohm-cm volume resistivity.
Key features
- High-purity, semiconductor-grade epoxy underfill for flip-chip encapsulation
- 4,000 cP viscosity for capillary flow and high-speed jetting
- Suitable for small die and devices with stand-off heights above 25 µm
- Self-filleting flow behaviour designed to limit bulky material accumulation on top of the device
- Corner-dot dispense process with 100°C substrate preheat
- Fast cure in 30 minutes at 150°C or 15 minutes at 165°C
- Engineered for 260°C peak lead-free reflow exposure
Applications
- Flip-chip underfill encapsulation
- Higher-temperature semiconductor package applications
- Small-die and fine-gap assemblies with stand-off heights above 25 µm
- Assemblies requiring subsequent over-moulding and lead-free reflow compatibility
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Physical Properties
Electrical Properties
Thermal Properties
Chemical Properties
Additional Information
CoolTherm® ME-531 Underfill Encapsulant
A one-part, semiconductor-grade epoxy underfill developed for flip-chip device encapsulation and higher-temperature package requirements. ME-531 combines 4,000 cP viscosity with capillary-flow and jetting capability, a 140°C cured Tg, controlled thermal expansion, low ionic contamination, and structural strength for subsequent over-moulding.
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Low-viscosity frozen underfill properties
ME-531 is supplied as a frozen black liquid. The viscosity value is tied to the published CP40 test at 5 rpm and 25°C.
| Property | Typical value | Context |
|---|---|---|
| Appearance | Black, low-viscosity liquid | One-part semiconductor underfill. |
| Viscosity at 25°C | 4,000 cP | CP40, 5 rpm. |
| Specific gravity | 1.71 | Typical as-supplied value. |
| Gel time at 150°C | 6 minutes | Gel time is not equivalent to the full cure schedule. |
| Working life at 25°C | 16 hours | Ambient working-life value after conditioning. |
Thaw upright, preheat the substrate, purge, dispense by corner dot or validated jetting, and cure
Warm the frozen syringe naturally to room temperature, ideally 20–25°C, while keeping it vertical with the dispense tip facing downward. For the documented capillary process, preheat the substrate to 100°C before application.
- Do not accelerate thawing with ovens, hot plates, hot-air guns, warm water, or other artificial heat sources.
- Mount the syringe on thoroughly cleaned dispensing equipment.
- Purge until an unbroken flow of underfill is extruded.
- Dispense as a corner-dot extrusion for capillary flow, or use a separately validated high-speed jetting process.
- Cure for 30 minutes at 150°C or 15 minutes at 165°C.
- Remove uncured material with acetone or isopropanol, subject to substrate and process compatibility.
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Allow the frozen syringe to reach 20–25°C naturally with the tip facing down.
For capillary application, preheat the substrate to 100°C to reduce underfill time.
Establish continuous flow and apply a corner dot or validated jet pattern.
Allow the designed fill process and cure for 30 minutes at 150°C or 15 minutes at 165°C.
Frozen storage and handling
Shelf life is six months when stored at -40°C in the original unopened container. Keep the syringe vertical with the dispense tip facing downward and do not store it horizontally. Transfer received material promptly to frozen storage, use first-in/first-out inventory control, wear insulated gloves when handling frozen containers, and review the current regional SDS and product label before use.
Thermal, mechanical, electrical and ionic properties
The values below are typical cured-material or joint-test results. They do not independently establish package-level warpage, voiding, solder-joint stress or reliability for every die, substrate, gap and process.
| Property | Typical value | Context |
|---|---|---|
| Glass transition temperature | 140°C | By TMA. |
| Coefficient of linear thermal expansion | 21 ppm/°C α1; 85 ppm/°C α2 | Below- and above-Tg regions must remain distinct. |
| Thermal conductivity | 0.5 W/m·K | Hot Disc Transient Method, ISO 22007-2. |
| Volume resistivity at 25°C | 1 × 1015 ohm-cm | Bulk electrical property; not an assembly working-voltage rating. |
| Die-shear strength | 9,000 psi | Tested joint result; specimen details are not stated in DS3738. |
| Storage modulus | 6,000 MPa | Cured-material modulus under the supplier test condition. |
| Moisture absorption | <0.5% | Duration and conditioning details are not stated in DS3738. |
| Extractable chloride | <10 ppm | Extractable ionic-contaminant result. |
| Extractable sodium | <5 ppm | Extractable ionic-contaminant result. |
| Extractable potassium | <1 ppm | Extractable ionic-contaminant result. |
Higher-temperature flip-chip underfill with capillary and jetting options
ME-531 is directly positioned for flip-chip underfill encapsulation, including higher-temperature applications. It is described for small die and stand-off heights above 25 µm, with adhesion to laminate, ceramic, solder mask and metal surfaces. Package-level validation must address the actual gap, die dimensions, jet or corner-dot pattern, fill path, fillet geometry, surface condition, cure and subsequent reflow or over-moulding process.
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Microelectronic Materials Catalogue — PC3003
The catalogue identifies ME-531 as a high-purity, one-component underfill with 4,000 cP viscosity, 30-minute cure at 150°C or 15-minute cure at 165°C, 0.5 W/m·K thermal conductivity, 1 × 1015 ohm-cm volume resistivity and 140°C Tg.
Open the Microelectronic Materials CatalogueElectronic Materials Handling — -40°C Storage
UI3022 provides frozen-storage orientation, insulated-glove guidance, FIFO handling, ambient thawing, typical thaw times, condensation removal and syringe-tip purging instructions.
Open the -40°C handling instructionsValidate ME-531 for your capillary or jet-underfill process
Krayden can help review package gap, stand-off height, substrate preheat, jetting or corner-dot pattern, dispense volume, capillary-flow time, fillet geometry, frozen handling, cure, reflow, over-moulding, ionic requirements and package-level reliability for CoolTherm® ME-531.
