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Harmonization Code : 3907.30.00.90 |   Polyacetals, other polyethers and epoxide resins, in primary forms; polycarbonates, alkyd resins, polyallyl esters and other polyesters, in primary forms : Epoxide resins : Other
Main features
  • One component
  • Chipbonder
  • Very High dispense speed

Product Description

LOCTITE 3621 epoxy adhesive is a Chipbonder designed for the bonding of surface mounted devices to printed circuit boards prior to wave soldering. Particularly suited for applications where very high dispense speeds, high dot profile, high wet strength and good electrical characteristics are required. Particularly suited where dispense speeds greater than 35,000 dots/h are required. Dispense speed ranges from 25000 to 50000 dots per hour.

LOCTITE 3621 has been used successfully for small part bonding in lead free processes with water and alcohol based fluxes under conditions outlined in the Environmental Resistance section.

Common cure schedule

  • 30 minutes @ 150°C 

Note: Sufficient time must be added to allow the bond location to reach the desired cure temperature. Curing profiles should be developed for each device. Bond strength achieved in practice will vary considerably depending on the SMD component type, adhesive dot size and the type, grade and degree of cure of the solder mask/resist.

Product Family
30cc Syringe 10cc Syringe

Catalog Product

Unlike other products we offer, the products listed on this page cannot currently be ordered directly from the website.
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Technical Specifications

General Properties
Specific Gravity
Specific Gravity
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.
Mechanical Properties
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
Viscosity 3,000 MPa.s
Electrical Properties
Volume Resistivity
Volume Resistivity
Volume resistivity, also called volume resistance, bulk resistance or bulk resistivity is a thickness dependent measurement of the resistivity of a material perpendicular to the plane of the surface.
1.3x1015 Ohms⋅cm
Dielectric Constant
Dielectric Constant
Dielectric Constant (k), commonly known as relative permittivity, is a number relating the ability of a material to carry alternating current to the ability of vacuum to carry alternating current.

It determines the ability of an insulator to store electrical energy and is the ratio of electric permeability in vacuum against the electric permeability of a material.

The lower the dielectric constant (κ) and dissipation factor, the less energy is absorbed from an electric field, making it a much better insulator.

It is a dimensionless property that can be affected by various factors such as the
thickness uniformity of a material, insufficient contact between the sample and electrodes, water adsorption and contact resistance.
Dielectric Constant @ 1000 kHz 2.79
Thermal Properties
Glass Transition Temperature (Tg)
Glass Transition Temperature (Tg)
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.
110 °C
Thermal Conductivity
Thermal Conductivity
Thermal conductivity describes the ability of a material to conduct heat. It is required by power packages in order to dissipate heat and maintain stable electrical performance.

Thermal conductivity units are [W/(m K)] in the SI system and [Btu/(hr ft °F)] in the Imperial system.
0.3 W/m.K
Coefficient of Thermal Expansion (CTE)
Coefficient of Thermal Expansion (CTE)
CTE (Coefficient of thermal expansion) is a material property that is indicative of the extent to which a material expands with a change in temperature. This can be a change in length, area or volume, depending on the material.

Knowing the CTE of the layers is helpful in analyzing stresses that might occur when a
system consists of an adhesive plus some other solid component.
Coefficient of Thermal Expansion (CTE), α1
Coefficient of Thermal Expansion (CTE), α1
CTE α1 (alpha 1) is the slope of the Coefficient of thermal expansion in a temperature range below the Glass transition temperature (Tg).

It explains how much a material will expand until it reaches Tg.
100 ppm/°C
Coefficient of Thermal Expansion (CTE), α2
Coefficient of Thermal Expansion (CTE), α2
CTE α2 (alpha 2) is the slope of the Coefficient of thermal expansion in a temperature range above the Glass transition temperature (Tg).

It explains the extent to which a material will expand after it passes Tg.
218 ppm/°C