Robust Interconnect Protection Helps Advance Cu Pillar Flip-Chip Designs


New Henkel NCP Material Enables Next-Generation Flip-Chip Devices

Expanding on its market-leading underfill portfolio, The Electronics Group of Henkel has developed a new non-conductive paste (NCP) material, LOCTITE ECCOBOND NCP 5209.

Designed to enable the move toward fine-pitch flip-chip architectures, LOCTITE ECCOBOND NCP 5209 delivers comprehensive underfill protection that overcomes the challenges associated with conventional capillary underfill materials.

“The demand for higher-function, miniaturized devices is driving packaging specialists toward fine-pitch flip-chip designs,” explains Matt Hayward, Semiconductor Liquids Global Product Manager for The Electronics Group of Henkel. “To enable this shift, new flip-chip bump technologies such as copper pillar are increasingly being employed because of their adaptability for ultra-fine pitches and better electrical connections. The reality is, only NCP can deliver the protection required within such tight dimensions.”

For devices where pitches are less than 100 µm and gaps are less than 40 µm, traditional capillary underfills are challenged. Because capillary action is driven by the gap distance and the vacuum action within the gap, new flip-chip constructions such as copper (Cu) pillar limit capillary underfill’s ability to flow within the high-density dimensions, which may result in reduced reliability. To overcome these issues, many packaging specialists are turning to thermal compression bonding with NCP materials.

LOCTITE ECCOBOND NCP 5209 is pre-applied onto the substrate, facilitating bump protection and interconnection in a single step. Formulated for Cu pillar bumps and Cu OSP substrate pad finishes, the novel underfill offers excellent bump reinforcement and safeguarding for devices with pitches of less than 100 µm and gaps less than 40 µm. With good dispensing capability and exceptionally long stage life of up to two hours at 70°C, LOCTITE ECCOBOND NCP 5209 provides the flexibility required for dynamic manufacturing environments.

When it comes to reliability, LOCTITE ECCOBOND NCP 5209 is equally impressive, with testing results that prove its robustness for long-term, in-field performance. The material has passed MSL3 testing, can withstand thermal cycling of up to 1,000 cycles and is capable of high-temperature storage of up to 1,000 hours at 150°C.

“Henkel’s leadership in advanced underfill development is incomparable,” says Hayward, who notes the company’s decades of underfill formulation success for semiconductor and surface-mount assembly technologies. “We understand the nuances of different applications, the requirements for each and the customized underfill chemistries necessary for success. LOCTITE ECCOBOND NCP 5209 is built on a foundation of more than ten years of NCP design expertise. We know the complexities associated with protection of Cu pillar flip chips and have addressed them with this material.”