LOCTITE ABLESTIK ABP 8068TB
- Good workability
- High thermal stability
- Solder replacement
LOCTITE ABLESTIK ABP 8068TB is a silver-filled semi-sintering die attach adhesive designed for semiconductor packages with high thermal and electrical requirements. It is formulated with a more enhanced resin bleed control than its predecessor LOCTITE ABLESTIK ABP 8068TA and it is designed to replace Pb Solder in Power and Low noise amplifier (RF SiP) type consumer applications. It is also a great solution for VCSEL (Vertical Cavity Surface Emitting Lasers) attach for 3D sensors.
LOCTITE ABLESTIK ABP 8068TB is designed to provide high adhesion and low stress which are essential for the thermal and reliability performances of high end power packages. The thermal performance of this material is comparable to that of a solder paste product (>100 W/mK thermal conductivity). It passes MSL 2A and MSL3 tests. This product was called ICP 9000 before being renamed to align with our new naming convention.
LOCTITE ABLESTIK ABP 8068TB is not compatible with bare copper but it works fine and provides good sintering with Ag or Au electroplated Cu, Ag and PPF leadframes. Applying a silver or gold spot can also help prevent copper oxidation and provide a reliable joint. It is an ideal solution for dies that are smaller than 2x2 - 3x3 mm and it can be fast and easily processed with standard die attach equipment
| Work life @25°C |
Work life @25°C
Work life is the amount of time we have to work with a material until it is no longer able to be easily worked and applied on a substrate.
It is based on the change in viscosity and it can rely on the application requirements.
| 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 |
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
The viscosity of a material can be decreased with an increase in temperature in
order to better suit an application
|Moisture absorption||0.21 %|
| 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.
| 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.
LOCTITE ABLESTIK ABP 8068TB can be used for Screen printing. But what is the process and what should you be careful of?
What stencil material should we use?
We have found that it is easier to achieve good results with a metal stencil (50um thickness seems ideal), compared with screen printing with a mesh (which tends to give a lower thickness and a rougher surface to the adhesive). Laser cut stainless is OK for a quick feasibility study, but I would recommend electroformed Nickel for good quality , high volume manufacturing.
Bleeding under the stencil?
It might be caused by too hard stencil unable to make a perfect fit with the substrate, due to the surface morphology. Using a mesh screen with an emulsion backing would probably solve this, but bring other processing issues.
Are there dimples?
Those can be caused as the stencil separates from the substrate, pulling up the edges of the printed adhesive. This can be improved by polishing the stencil apertures. Lower viscosity ABP 8068TA may be also worth testing in parallel if you observe dimple effects (although 8068TA also has a high thixotropic index of 6 for dispensing purposes)
Recommendations for aperture reduction and post cure cooling rate?
Aperture reduction needs to be established by DOE trials, as it depends on component size, stencil thickness and customers inspection requirements. Regarding cooling rate, we do not believe this is critical, but thermal shock should be avoided. Normal practice is to allow parts to cool fairly slowly in the oven until below about 70C (when they are safe to handle).
What are the optimal Printing parameters?
Those will depend on the design of the print pattern and the equipment used, but the following will be a good starting point:
- Print speed: 30 mm/s
- Force: 12 kg
- Print gap: The Print Gap should be set to Zero mm (stencil is in contact with substrate during print). And the Separation Speed (the rate at which the palette drops away from the stencil) should be set to 2 or 3 mm/sec. The Separation distance should be at least 2mm.
- Squeegee material: Stainless is good. Rubber will deform into stencil opening & reduce the glue thickness. Rubber is good with a mesh screen, but not usually suitable for metal stencil.
- Squeegee angle: Not really critical. Use what is available – typically 45 or 60 degrees.
- Die placement force: This depends on the component size. Suggest to start with parameters for conventional silver filled die attach paste. Aim for BLT = 25 um after cure (and a minimum of 10um).
For die size
- 20 minutes ramp from 25°C to 130°C, hold for 30 to 60 minutes; 15 minutes ramp to 200°C, hold for 120 minutes in N2 or air oven
For die size >5 x 5 mm
- 20 minutes ramp from 25°C to 130°C, hold for 120 minutes; 15 minutes ramp to 200°C, hold for 120 minutes in N2 or air oven
Alternate Cure Schedule
Suitable for Ag, Au and PPF substrates
- 20 minutes ramp from 25°C to 130°C, hold for 30 minutes; 10 minutes ramp to 175°C, hold for 60 minutes in N2 or air oven