Underfill Adhesives
DELO MONOPOX underfill adhesives are designed to support reliable semiconductor packaging and board level assembly by capillary filling the gap between a device and its substrate after solder reflow. These materials help protect Flip-Chip, CSP and BGA solder joints, improve mechanical stability, and support long term reliability in advanced electronic assemblies.
What do Capillary Underfill Adhesives do?
Capillary underfill adhesives are dispensed along the edge of a semiconductor component and flow underneath the device by capillary action, without the need for external pressure. Once cured, the underfill encapsulates the solder joints and provides additional mechanical reinforcement.
These materials are used to compensate for coefficient of thermal expansion mismatch between different materials within the assembly, helping to protect solder joints during thermal cycling and reduce the risk of failure over time. They also improve resistance to moisture ingress, delamination, shock, vibration and other mechanical stresses that can affect package reliability.
In advanced packaging applications, capillary underfills are increasingly important as semiconductor packaging moves towards chiplet based and heterogeneous integration. This trend increases flow distance while interconnect pitch continues to decrease, placing greater demands on flow behaviour, void control and material purity.
More detailed information on DELO’s Underfill adhesives can be found here.
Key Features of DELO MONOPOX Underfill Adhesives
- Capillary flow into narrow gaps after solder reflow.
- Improves solder joint protection during thermal cycling.
- Helps compensate for CTE mismatch between device and substrate.
- Enhances resistance to moisture ingress and delamination.
- Improves mechanical robustness against shock and vibration.
- Extended working life of 3 days
- Filler top cut of 5µm for gaps < 100µm
- High glass transition temperature (Tg) of 150°C, low CTE of 24 ppm/K
Why underfill is critical in semiconductor packaging
Underfill adhesives play a key role in modern semiconductor assembly because they redistribute stresses generated by thermal expansion differences inside the package. By surrounding and supporting the solder joints, they help improve overall mechanical integrity and extend assembly life in demanding environments.
This is particularly important in applications where devices are exposed to repeated thermal cycling, vibration, or moisture. As package designs become more advanced, underfill performance becomes a major factor in long term reliability.
DELO underfill adhesives have been subjected to extensive testing, including aging in extreme conditions, followed by thermal cycle testing between -40ºC & +150ºC.
Suitable for manual to fully-automatic placement equipment
DELO underfill adhesives are optimised for syringe dispensing, so can be used in manual to fully-automatic placement equipment.
Got a Question About Underfill Adhesives?
Whether you’re developing a new product or refining an existing process, Inseto’s team of experts is here to help.
From flow behaviour and curing requirements to selecting the right material, we provide technical guidance, documentation, and samples to support your application needs.
Knowledge Base Articles
Description
Description
Capillary Underfill Adhesives (IKB-097)
Link
Description
Understanding Shear Test: Ball Bond and Die Shear (IKB-018)
Link
Description
Basic Adhesive Types (IKB-041)
Link
Description
How to Choose the Right Adhesive (IKB-035)
Link
Description
Adhesives for Die Attach (IKB-071)
Link
Description
Die Attach Process: Guidance and Setup (IKB-072)
Link
Related Products
Further Information
Applications
Underfill of CSP, BGA, Flip Chip and other semiconductor devices.
Industry Segments
Microelectronic / Hybrid Assembly, Semiconductor Assembly / Back-end Assembly etc., Fibre Optics / Photonic Assembly, Microwave Electronics, OEM Equipment Manufacturers, Precision Components & Assemblies, PCB Assembly, Electronic Component / Device Assembly, Smart Cards, Smart Labels, RFID, Automotive Electronics etc.
Delo Website
Region
Available from Inseto in the United Kingdom & Ireland
Request Form
Back to top