LOCTITE ABLESTIK QMI3555

Harmonization Code : 3506.91.90.99 |   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 ; Adhesives based on polymers of headings 3901 to 3913 or on rubber; Other ; Other
Main features
  • Wide processing window
  • Silver/Vanagium glass
  • Reworkable at less than 350°C

Product Description

LOCTITE ABLESTIK QMI3555 is formulated using a Polymodal Metal Flake distribution technology which utilizes a combination of specifically selected silver flakes that, in conjunction with a unique glass, maximizes adhesion to gold while simultaneously enhancing rheological properties of the paste. It is a No-Dry paste that possesses rheological properties which optimize dispensability during die attach and it is reworkable at less than 350°C.

LOCTITE ABLESTIK QMI3555 incorporates a patented silver/vanadium glass at a metal to glass ratio of 6.5:1 by weight. The paste is completely resinless and fires into a film that provides high thermal and electrical conductivity as well as excellent initial adhesion. It is extremely resistant to degradation during temperature cycling from -65°C to + 150°C.

A thin bondline combined with its excellent thermal properties make QMI3555 attractive for use in high power devices. Because of its wide processing range, one common low temperature firing profile can be used for both solder and glass sealed packages with nearly all die sizes.

Compared to LOCTITE ABLESTIK QMI 3555R, the R in QMI 3555R stands for RESIN, so the QMI 3555R (resin) version contains ~0.1% by weight of resin added compared to QMI 3555 to slow down solvent drying.  Technically both products have comparable properties after cure.

 

Product Family
QMI3555  
2 oz jar

Catalog Product

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

Technical Specifications

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.
10
Viscosity
Viscosity
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
35,000 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)
10 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
Thermal Properties
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.
80 W/m.K

Additional Information

What is the difference between QMI3555 and QMI3555R?
The R stands for RESIN, so the QMI 3555R (resin) version contains ~0.1% by weight of resin added over QMI3555 to slow down solvent drying. Technically both products have comparable properties after cure.

QMI 3555 can be fired at temperatures between 300°C and 450°C on bare ceramic. On gold plated parts, the minimum peak should be 325°C. The minimum dwell time should at least be 14 minutes above 300ºC when the peak is <325ºC. Higher peak temperatures require less dwell time. The material is completely resinless and contains only low boiling solvents that are involved during the early stages of the firing process.

See the Technical Data Sheet for Firing profiles.


Can you pack QMI3555 in smaller syringes?

Henkel is supplying such "silver glass type of QMI 3555" die attach adhesives only in 2 ounce (155g) jars because of the silver settlement risk in the syringe and serious Free Thaw Voiding (FTV) issues in case such syringes would be stored at -40C and come back to ambient temperature. This will lead to microvoids in the syringe and consequently also in the bond line after dispensing.

One way to prevent this "micro voiding in the syringe" after down filling (if it happens) could be to add a centrifuging step on the syringes prior to dispensing :

  • Use syringe kits from Nordson or similar (without the pistons inserted)
  • Fit a tip cap, and hold the syringe vertical
  • Pour some Ag glass into the syringe (it needs a steady hand, and a bit of practice, but it’s not difficult)
  • Insert a piston (white or beige should work OK, try to avoid getting 3555 trapped between the piston & the syringe wall)
  • Fit a top cap to seal the syringe
  • Now – mix/degas the material in the syringe using "centrifuging equipment" as described below
    • Thinky ARE-250 or ARE-310 mixer (available from Intertronics) or a “Speedmixer” from Synergy Devices would work well
    • Vacuum versions of these mixers should be available, which will work better than non-vacuum versions, but may not be needed
    • The process takes about 5 mins, but parameters should be optimized by DOE at the customers site
  • Check the syringe, and push the piston down onto the surface of the 3555, if it lifted during the degassing
  • The syringe is now ready to use and should be used  within the same shift to prevent the settling of the silver in the syringe (or centrifuge again prior to use)
     

Such (vacuum) centrifuging equipment is commonly used in semiconductor back-end assembly.

tl;dr no QMI 3555 in syringes available, but process can be optimized using (vacuum) centrifuging equipment ….