ABLESTIK 293-21

Main features

Strong Bonding to Difficult Metallic Substrates
90-Minute 75 deg C Cure
1.0 x 10^13 ohm-cm Volume Resistivity

Product Description

LOCTITE ABLESTIK 293-21 is a black, one-component, heat-cure epoxy adhesive for general assembly bonding to difficult-to-bond substrates. Documented substrate classes include gold, nickel surfaces, silver, copper, and brass. The adhesive has a typical viscosity of 28,000 mPa.s (cP) at 25 degC, a 3-hour work life at 25 degC, and heat-cure schedules ranging from 4 hours at 75 degC to 45 minutes at 120 degC. The cured material combines high electrical resistivity with documented dielectric, thermal, and mechanical properties.

Key features

One-component epoxy: Heat-cure adhesive supplied as a black paste for general assembly bonding.
Difficult-substrate bonding: Documented for gold, nickel surfaces, silver, copper, and brass.
Moderate-temperature cure options: Guideline schedules include 4 hours at 75 degC, 90 minutes at 100 degC, or 45 minutes at 120 degC.

Applications / Suitable for

General assembly bonding
Bonding gold and nickel surfaces
Bonding silver, copper, and brass substrates

TDS, SDS & Technical Documents

Technical Specifications

General Properties

Chemistry Type

Epoxy

Work life @25°C

3 hours

Thermal Properties

Glass Transition Temperature (Tg)

36 °C

Thermal Conductivity

0.25 W/m.K

Electrical Properties

Volume Resistivity

1.0×10¹³ Ohms⋅cm

Additional Information

One-Component Electronics Assembly Epoxy

LOCTITE ABLESTIK 293-21

A black, one-component epoxy adhesive for heat-cured general assembly bonding. It is intended for strong, resilient bonds to difficult-to-bond substrates and is documented for gold, nickel surfaces, silver, copper, and brass. The cured material provides high electrical resistivity together with dielectric, thermal, and lap-shear data for product evaluation.

One componentHeat cureBlack pasteDifficult-to-bond surfaces

As-supplied properties

Viscosity

28,000 mPa s

Typical as-supplied viscosity at 25 deg C.

Work life

3 hours at 25 deg C

Use this value for process planning rather than as a guaranteed open-time specification.

Typical as-supplied, work-life, storage, and current SDS physical-property data.
Property	Value	Unit	Method / condition
Technology	Epoxy	-	As supplied
Appearance	Black paste	-	As supplied
Components	One-component	-	Product characteristic
Viscosity	28,000	mPa s (cP)	25 deg C
Work life	3	hours	25 deg C
Shelf life	365	days	-40 deg C
Specific gravity	1.9	-	Current U.S. SDS
VOC content	11	g/L	Current U.S. SDS

Surface Preparation, Material Conditioning and Heat Cure

Processing and cure

Carefully clean and dry the bonding surfaces. Remix the product thoroughly before use because some separation during shipping and storage is possible. Apply the adhesive to the prepared surfaces, assemble the parts, and maintain contact until cure is complete. Contact pressure is documented as adequate for the referenced bonding procedure.

Cure option 1: 45 minutes at 120 deg C.

Cure option 2: 90 minutes at 100 deg C.

Cure option 3: 4 hours at 75 deg C.

Low-temperature crystallization: If crystallization occurs after cold storage, the TDS permits a gentle warming cycle of 52 deg C for 30 minutes so crystallized ingredients can redissolve before use.

Cure schedules are guideline recommendations. Actual cure conditions may vary with the application, cure equipment, oven loading, and actual oven temperature.

Storage and handling

Store unopened product in a dry location at the stated optimal storage temperature of -40 deg C. The typical shelf life is 365 days at -40 deg C. The TDS cautions that storage either below or above -40 deg C can adversely affect product properties. The current U.S. SDS likewise specifies safe storage at or below -40 deg C. Keep the container tightly closed until use and do not return removed material to the original container.

Cured properties

Aluminum lap shear

31.0 N/mm^2

Typical Al-to-Al lap shear at 25 deg C; 4,500 psi.

Volume resistivity

1.0 x 10^13 ohm-cm

Typical value at 100 deg C; relevant to evaluating electrically insulating bonded assemblies.

Typical cured mechanical, thermal, and electrical properties. Values remain tied to the stated conditions and are not guaranteed specifications.
Property	Value	Unit	Method / condition
Hardness	80	Shore D	Cured material
Thermal conductivity	0.25	W/(m K)	121 deg C
Glass transition temperature	36.0	deg C	Cured material
Coefficient of thermal expansion, below Tg	175	ppm/deg C	As reported in supplier TDS
Coefficient of thermal expansion, above Tg	68	ppm/deg C	As reported in supplier TDS
Dielectric strength	900	volts/mil	Cured material
Dielectric constant / dissipation factor	3.7 / 0.008	-	Cured material; frequency not stated in supplied TDS
Volume resistivity	1.0 x 10^13	ohm-cm	100 deg C
Al-to-Al lap shear strength	31.0	N/mm^2	25 deg C; 4,500 psi

Documented Substrate Scope

Applications

LOCTITE ABLESTIK 293-21 is positioned for general assembly bonding where difficult-to-bond metallic surfaces are part of the design. Suitability should be confirmed for the exact substrate finish, surface preparation, joint geometry, cure profile, and operating environment.

Gold and Nickel Surfaces

Both gold and nickel surfaces are explicitly listed as supported substrate classes for this adhesive.

Silver, Copper and Brass

The documented substrate list also includes silver, copper, and brass for general assembly bonding evaluation.

Electrically Insulating Bonding

High volume resistivity and documented dielectric properties support evaluation where the cured adhesive is expected to provide electrical insulation as part of the bonded assembly.

Next steps

Evaluate LOCTITE ABLESTIK 293-21 for Your Assembly

Krayden can support evaluation of surface preparation, difficult-to-bond metallic finishes, material conditioning after frozen storage, cure-profile selection, joint design, and electrical or thermal requirements. Application trials should confirm performance for the intended substrate, geometry, cure, and service conditions.