Underfills

To help manufacturers address the challenges within specific industries, Henkel has the most robust range of underfills. Our innovative capillary flow, edge, and corner bond underfills for CSP, BGA, WLCSP, LGA and other similar devices lower stress, improve reliability, and offers outstanding results.

Underfills are used in manufacturing delicate electronic packages for the automotive and electronics industries, among others. Underfills are also used to provide mechanical reinforcement to the solder joints and solder balls that connect a chip to a printed circuit board. The underfill reinforces the package to the board via capillary action. This helps to prevent mechanical fatigue and extend the lifespan of the assembly.

Henkel has developed a range of underfills, with each offering a particular property requirement. These underfills have been specially formulated to offer manufacturers a reliable, high-quality product. Using Henkel underfill solutions in the production of CSPs, BGAs, WLCSPs, and other components can enhance performance and improve the lifespan of a manufacture’s products.

Higher I/O counts, package integration, and tighter bump pitches are dictating the use of flip-chip technology to enable advanced package designs. Given these realities, protecting next-generation flip-chip and package-on- package (PoP) devices is more important than ever to safeguard against stress and ensure long-term function and reliability of the component  Underfills in a variety of formats protect delicate, high-density flip-chip connections and Henkel’s capillary underfill (CUF) and non-conductive pastes and films (NCP and NCF) offer proven success.

Underfills are usually applied to the package after reflow. Traditional capillary underfills are dispensed to flow in between the solder balls of Ball Grid Arrays (BGAs) and Chip Scale Packages (CSPs) enhancing mechanical and thermal properties.

These products provide solutions to a number of challenges. Our underfills can be used to help reinforce electronic components and minimize stress. They also offer excellent protection of solder joints during thermal cycling. 

Contact us to learn more about our high-quality underfills and to ask any industry specific questions about our product range.

Underfill material solutions

Our Underfill Product Line

Henkel’s LOCTITE^® ECCOBOND and LOCTITE^® underfills offer the highest levels of reliability with the options of both reworkable and non-reworkable formulations. Materials are available that deliver ultimate processability with fast flow speeds and the capability to effectively fill bottom-side component spaces with extremely low bump heights. Formulations are designed to reduce stress caused by mismatched expansion coefficients and have outstanding reliability in thermal cycling, thermal shock, drop testing, and other demanding tests, as well as in use.

To enhance the reliability of many handheld devices, Henkel’s LOCTITE^® portfolio of underfills offers formulations that quickly fill the space between the package and board, cure fast, offer outstanding protection for solder joints against mechanical strains such as shock, drop and vibration, and allow for reworkability. For applications where full underfill is not required, LOCTITE^® cornerbond and edgebond technologies provide a cost-effective solution, with strong perimeter reinforcement and self-centering capability.

LOCTITE^® ECCOBOND and LOCTITE brand underfills, available in pre- and post-applied formulations, deliver the highest levels of reliability with wide processability and good gap filling of ultra-fine-pitch, low bump height devices. Designed to reduce stress caused by mismatches in the coefficient of thermal expansion (CTE), Henkel underfill materials have exhibited outstanding reliability in thermal cycling as well as high temperature storage testing and in use.

Underfill Subsets

1. Underfill CSP - The use of chip scale packages (CSPs) has expanded rapidly in recent years. CSPs are most commonly used in electronic assembly. Underfills are often used to help increase the mechanical strength of the CSP-to-board connection and to ensure CSPs meet mechanical shock and bending requirements.
2. Underfill BGA – Many manufacturers use underfill BGA packaging in order to strengthen solder joints and reinforce a product's resistance to vibration and thermal shock.
3. Underfill WLCSP – Underfills can significantly improve the dropping performance and raise the thermal cycle performance of Wafer Level Chip Scale Packages (WLCSPs). This helps to extend the lifespan of WLCSPs.
4. Underfill LGA – Land Grid Array (LGA) devices can also benefit from underfills. Underfills are used to enhance LGA mechanical strength and reliability.
5. Partial underfill – Corner or edge bond underfills are more thixotropic than standard capillary flow solutions and dispensed or jetted on the outer sections of a package resulting in enhanced reinforcement. Henkel offers material solutions not only in full capillary flow, but also semi-reinforcement solutions such as edge and corner bond adhesives.

Capillary Underfill (CUF) Materials

Capillary underfill materials applied after chip placement are designed with optimized rheology for deposition consistency and uniform flow. Henkel’s capillary underfills for flip-chip applications are formulated with small fillers to enable good jetting performance, fast flow, and thorough bump protection. With a long stage life at 90°C and compatibility with standard and pressure ovens, the Henkel portfolio of capillary underfills offers manufacturing flexibility and good reliability performance for a variety of flip-chip applications.

Non-Conductive Pastes (NCP)

The use of copper (Cu) pillar technology to increase bump density for higher I/O may present challenges for traditional capillary underfills, as thorough gap filling of tight dimensions can be difficult. To ensure robust bump protection against stress, Henkel’s pre-applied non-conductive paste (NCP) provides a high-reliability alternative. The low-viscosity NCPs deliver excellent fluxing ability for the formation of high-integrity solder joints, fast curing capability for high throughput volume production, and a high glass transition temperature (Tg) that enables in-application reliability.

Non-Conductive Films (NCF)

For applications such as high bandwidth memory where 3D through-silicon-via (TSV) stacking technology is growing and ultra-fine-pitch Cu pillar technology is employed, non-conductive films are emerging as the pre-applied materials of choice for die that are less than 100 µm thick. Applied at the wafer level, NCFs provide excellent bump protection and wafer processing support. Henkel NCFs are formulated with ultra-fine fillers to accommodate tight dimensions and deliver optimized flow for fillet control, allowing close die placement. Easily processed with low melt viscosity, Henkel NCF materials enable high reliability for next-generation advanced packaging architectures.

Contact us to learn more about our high quality underfills and to ask any industry specific questions about our product range.

Industrial Applications for Underfills

Underfill is used in the manufacture of a large number of electronic parts. It helps to stabilize and reinforce solder joints and raise the thermal cycle performance of otherwise delicate components.

Underfills are being increasingly used to manufacture portable devices due to:

• Finer pitch packages
• POP packages
• More compact PCBs
• Challenging drop test requirements
• Larger BGA, CSPs, and WLCSPs

These issues have come about because of the growing demand for lighter, smaller devices, and improved reliability. Adding underfill to these products helps to enhance the performance of these precision pieces and allows manufactures to maintain a high level of quality.

Automotive

As automotive electronics become increasingly sophisticated and widespread, the demand for reliable, high performance components has grown. Using underfill BGA and CSP, as well as second level underfill, in these components can help to improve durability.

Electronics

Underfill is used to enhance the lifespan of electrical chips. Henkel has designed a broad range of underfill solutions to satisfy a variety of device reinforcement requirements. From capillary flow underfills for BGAs, CSPs, PoPs, LGAs, and WLCSPs to materials that enhance flip chip reliability, our formulations alleviate interconnect stress while enhancing thermal and mechanical performance. For applications where full underfill is not required, LOCTITE^® corner bond and edge bond technologies provide a cost-effective solution, with strong perimeter reinforcement and self-centering capability.

There several key benefits when using LOCTITE^® underfill products for electronic applications:

• Fast cure
• Good flowability
• High reliability
• Good reworkability
• Excellent SIR performance

Further Resources

If you’d like to find out more about Henkel underfills, please download our brochure. If you can’t find the information you’re looking for, please feel free to contact a member of our team.

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