Henkel AG & Co. has announced the availability of a die attach adhesive that provides high thermal capability to enable superior operation of power semiconductor packages.

As integrated circuits (ICs) become denser and more complex, particularly in the power device sector, new approaches to die thermal control and electrical performance are required. Loctite Ablestik 6395T is the latest in the company’s portfolio of high-thermal solutions. Specifically, it allows integration of back-side metalized or bare silicon (Si) die. Also, it features 30W/m-K thermal conductivity – among the market’s highest thermal performance without sintering.

Importance of Thermal Function to Die Performance

Elevated operational temperature is a key factor influencing die performance. Thus, thorough heat dissipation helps ensure functional execution and long-term reliability.

Henkel’s Global Market Segment Head for Semiconductor Packaging Materials, Ramachandran Trichur, explains the mechanism of heat transfer from the die and why material selection is critical. “For most high-power semiconductor packages, the primary path for heat dissipation from the device is through the die attach material. Because the material is in direct contact with the die, its thermal characteristics, which include material thickness, thermal conductivity, and thermal resistance are the most important. Loctite Ablestik 6395T’s 30W/m-K bulk thermal conductivity provides excellent heat transfer for metalized or bare Si die, ”explains Trichur.

Most high-power semiconductor applications, like those found in electric vehicles, industrial automation systems, and 5G infrastructure components, also demand good electrical conductivity. Too much electrical resistance between the die and the package results in energy loss. Also, it reduces the device’s energy efficiency. As in the case of thermal capabilities, package electrical performance is largely influenced by the die attach layer. This is true, especially in power ICs, where die attach is the most significant contributor to electrical resistance, or RDS (on). Loctite Ablestik 6395T improves energy efficiency by significantly lowering resistance.

In addition to its enabling electrical and thermal characteristics, Loctite Ablestik 6395T provides several processability, sustainability, and reliability advantages. These include:

• High reliability: It meets automotive grade 0 thermal cycling and MSL 1 reliability standards on die sizes up to 3.0×3.0mm;
• Compatibility with multiple die finish/lead frame combinations;
• Low, <5% volatile organic compound (VOC) content on cure;
• Longer work-life: enables high-density lead frame packaging with longer stage life and open time;
• No resin bleed out.

“While electrical and thermal capability are top priorities, a streamlined bill of materials is also important for customers. Loctite Ablestik 6395T allows metalized or non-metalized die integration, delivers lead frame flexibility, and allows for a wide die size range – all using a high-reliability formulation. Henkel has achieved this unique balance of supply simplification, processability, and thermal and electrical performance, effectively extending the company’s leadership in the high thermal die attach space,” says Trichur.