Harmonization Code : 3506.10.00.00 |   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
Main features
  • Bismaleimide resin
  • Low stress
  • No-bleed version of QMI536

Product Description

LOCTITE ABLESTIK QMI536NB is a low-bleed, non- conductive, PTFE-filled paste designed for stacked die applications which require very low stress and robust mechanical properties to prevent damaging the top die structure. The material has the same processing and properties of QMI536 but resin bleed is essentially eliminated. These features produce fast cure capability and enhanced reliability performance to a wide variety of surfaces, including solder resist, flexible tape, bare silicon and various die passivations.

LOCTITE ABLESTIK QMI536NB creates packages and devices that have high resistance to delamination and popcorning after multiple exposures to lead-free solder reflow temperatures. It has good optical performance with high transmittance, Optical Density and HRI and is  a great solution for ASIC attach and LED attach.

LOCTITE ABLESTIK QMI536NB is a Bismaleimide (BMI) based product. QMI products are typically lower modulus at 25C vs epoxies and therefore lower in strength. They make up for it at higher temps where they are typically higher in strength than epoxies, something very beneficial during reliability testing. At the same time their lower modulus (“flexibility”) is also leading to less stress during temp cycling, temp shock and vibration testing. Because of their high temperature stable and hydrophobic properties, such BMI materials have replaced many epoxy die attach materials when Pb free 260 reflow had to be survived.

LOCTITE ABLESTIK QMI536NB has been developed as a medium modulus (300MPa) and fast curing “No Bleed” dispense paste that is widely used for die attach in automotive sensor and consumer electronics applications. It can be cured at low temperatures down to 80°C and has a Dielectric Constant value of 3. You might also be interested in QMI 538NB that has a lower modulus (100MPa) and is used in MEMS and die stacking from the initial steps.

LOCTITE ABLESTIK QMI536NB has also been used successfully as an encapsulation in MEMS microphones in the past. The ~300 MPa modulus made it an ideal candidate for such an application when cured at 120°C

Cure Schedule

Cure Schedule

  • 30 minutes @ 150°C
Product Family
5cc Syringe

Catalog Product

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

Technical Specifications

General Properties
Curing Schedule
Curing Schedule
Curing schedule is the time and temperature required for a mixed material to fully cure. While this applies to materials that cure with heat, there are also other materials that can be cured with UV.

Even though some materials can cure on ambient temperatures, others will require elevated temperature conditions to properly cure.

There are various curing schedules depending on the material type and application. For heat curing, the most common ones are Snap cure, Low temperature cure, Step cure and Staged cure.

Recommended cure type, schedule, time and temperature can always be found on the Technical data sheets.
Cure Type Heat Cure
Density (g) 1.4 g/cm3
Pot Life
Pot Life
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.
12 hours
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.
Shelf Life
Shelf Life
Shelf life is the amount of time after manufacturing that a product is guaranteed to retain its properties.

It differs vastly per product and it is based on temperature and storage conditions.

The properties can be guaranteed for the temperature and time range indicated on the TDS since those are the ones tested to be the best for the product.
Shelf Life @ -40°C 365 days
Physical Properties
Thixotropic index
Thixotropic index
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 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
10,000 mPa.s
Chemical Properties
Ionic Content
Chloride (Cl-)
Chloride (Cl-)
The amount of Chloride (Cl-) ion extracted from the product in parts per million (ppm)
20 ppm
Potassium (K+)
Potassium (K+)
The amount of Potassium (K+) ion extracted from the product in parts per million (ppm)
20 ppm
Sodium (Na+)
Sodium (Na+)
The amount of Sodium (Na+) ion extracted from the product in parts per million (ppm)
20 ppm
Moisture absorption 0.35 %
Mechanical Properties
Shear strength
Shear Strength @25°C 16.9 N/mm2
Tensile Modulus
Tensile Modulus
Tensile modulus is a mechanical property that measures the stiffness of an elastic material. It is the slope of stress / strain curve of a material under direct tensile loading.

It can be used to predict the elongation or elastic deformation of an object as long as the stress is less than the tensile strength of the material. Elastic deformation is caused by stretching the bonds between atoms and the deformation can be reversed when the load is removed.

Tensile modulus is affected by temperature and is an important engineering attribute since we generally want to keep elastic deformation as small as possible.
Tensile Modulus @-65°C 1000 N/mm2
Tensile Modulus @150°C 50 N/mm2
Tensile Modulus @25°C 300 N/mm2
Tensile Modulus @250°C 50 N/mm2
Thermal Properties
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.
80 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.
150 ppm/°C
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.
-30 °C
Specific Heat Capacity
Specific Heat Capacity
Specific heat capacity is the amount of heat energy required to raise the temperature of a substance per unit of mass. The specific heat capacity of a material is a physical property. It is also an example of an extensive property since its value is proportional to the size of the system being examined.
1.5 J/(g⋅°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

Additional Information

How can we limit bleeding on non traditional finishes?

Bleeding is a complicated topic and very surface finish dependent. QMI 536NB has certain "Anti Bleed Agents", but is optimized to most commonly used lead frame finishes. As QMI 536NB is BMI resin based, it can be SNAP cured as well (comparable to QMI 519 and 550 for instance). In theory, 30sec @ 160°C or 1min @ 120°C should already cure this product for ~90%. It will probably take longer to develop full adhesion and relax the bond line, so a "post cure" bake of around 30min at 150°C would be good to finish full cure (or done during Post Mold Cure). Even few seconds @ 160°C will be sufficient to "gel" the material and stop any further bleed. Note that this is all based on bond line = adhesive temperature, so in oven this would need more time to warm up. This is a practical option to stop/reduce the bleeding of QMI 536NB on non-traditional finishes.

For volume production, die bonder suppliers may be able to fit a heater just after the die placement position. Another thing that might reduce the bleed is to bake the parts immediately before die attach – to make sure that they are dry (30min @ 125°C should be OK). 


DMA Modulus of QMI536NB

DMA Modulus of QMI536NB

The DMA Modulus curve shows the modulus of the QMI536NB over the temperature range from -100°C up to 300°C





Pull strength of Bismaleimide based resins in different temps
It has been observed that BMI based hybrids do not perform well on pull tests. BMI resin based QMI products are typically lower modulus at 25°C vs epoxies and therefore lower in strength. But, and that's the most important point, at higher temps they are typically higher in strength than epoxies, something that benefits high temp operation applications up to 200°C !

This lower modulus (“flexibility”) is also leading to less stress during temp cycling, temp shock and vibration testing.

Since it contains silanes, is this a silicone or an epoxy based resin?

BMI resin based adhesives are Silicone free! Silanes are added in small quantities as adhesion promoter. And to add to that since you're wondering how to classify it, we’re not aware of any BMI/epoxy cross contamination.


What is Optical Density?

Optical density is a logarithmic intensity ratio of the light falling upon the material, to the light transmitted through the material:

 How to calculate Optical Density- OD Formula

Though optical density and absorbance both measure the absorption of light when that light passes through an optical component, these two terms are not the same. Optical density measures the amount of attenuation, or intensity lost, when light passes through an optical component. It also tracks attenuation based on the scattering of light, whereas absorbance considers only the absorption of light within the optical component. Src

It is usual a point of confusion since people sometimes say it is the same as absorbance or define it as absorbance over the length.



QMI538NB is a lower modulus alternative for MEMS and die stacking from the beginning.