Flip Chip Bonding Services
High-Precision Micro-Electronic Interconnection Solutions

The flip chip assembly process begins with bump preparation on the die pads, creating raised electrically conductive structures that will form connections. OurPCB offers multiple bumping options including solder ball attach (to 305μm diameter), gold stud bumping (pitch down to 150μm), and anisotropic conductive adhesive for specialized applications. After bumping, components undergo precision placement where they’re inverted and aligned to PCB pads with accuracy to 0.5μm using advanced optical systems.

The bonding phase secures the semiconductor devices to substrates through various methods, including thermo-compression (for highest accuracy), thermosonic process (lower temperature), and hot air reflow for various solder types. Finally, the underfill process injects specialized epoxy material in the space between the die and the substrate, which distributes thermal expansion mismatch stresses and protects interconnections from environmental factors. OurPCB offers both standard and reworkable underfill options depending on your specific application requirements.

Understanding Under Bump Metallization (UBM)

Under bump metallization is a critical layer deposited on bond pads before the bumping process. OurPCB implements advanced UBM technologies that create robust interfaces between pad materials and bumps. Our UBM technology:

• Acts as an adhesive layer between pad and bump material
• Provides a diffusion barrier preventing intermixing of metals
• Creates a wettable surface for solder materials
• Prevents oxidation of underlying pad materials
• Enhances long-term reliability of chip connection

What Types of Flip Chip Bumping does OurPCB offer?

OurPCB provides multiple bumping technologies to optimize interconnect performance for different applications. Solder bump formation creates precise spherical connections using various alloy compositions including low-temperature (96 °C), eutectic (183 °C), and lead-free (217 °C) options. This versatility allows us to match thermal requirements to your specific substrate and component limitations, ensuring reliable connections without thermal damage.

Gold stud bumping creates highly conductive, fine-pitch interconnections ideal for applications requiring the highest electrical performance. Our capability extends to partial wafers and large die with pitch dimensions down to 150μm. For specialized applications, we also offer conductive adhesive flip chip technologies which provide unique advantages in certain optoelectronic and temperature-sensitive applications where traditional reflow process may not be optimal.

Specialized Bump Processing Techniques

• Electroplating process for wafer-level bumping with tight dimensional control
• Vacuum pick-up placement for separately manufactured solder balls
• Photolithography-based bumping with seed metal deposition
• Copper pillar bumping for advanced fine-pitch applications
• Controlled collapse chip connection for self-alignment during reflow

What Applications Benefit Most from Flip Chip on Board?

RF and microwave applications benefit significantly from flip chip on board due to dramatically reduced inductance in signal paths. The technology’s shorter connections deliver up to 70% lower parasitic inductance, enabling wireless devices to operate effectively at frequencies beyond 100GHz for next-generation communications systems. OurPCB’s precise placement capabilities ensure optimal performance in these demanding applications where signal integrity is paramount. Optoelectronic devices such as laser diodes, photodetectors, and optical transceivers require exceptional alignment precision to maintain optical functioning while providing necessary electrical connections. Our flip chip bonding technique integrates seamlessly with silicon photonics platforms, enabling optical-electrical integration critical for high-bandwidth data centers and telecommunications infrastructure. Additionally, the chip scale footprint of flip chip assemblies enables more compact designs in space-constrained portable electronics, IoT devices, and medical implantables.

How do we Address Thermal Expansion Challenges?

Thermal expansion mismatch between die and substrate materials presents a significant reliability challenge in flip chip assembly. OurPCB implements comprehensive solutions to manage coefficient of thermal expansion (CTE) differences effectively. Our underfill materials are specifically engineered to distribute mechanical stresses evenly across the solder joints during thermal cycling.

We use advanced finite element analysis during the design phase to predict stress concentrations and optimize both underfill selection and bump geometry. Our specialized corner bumping techniques provide additional mechanical reinforcement at the highest stress locations. This extends thermal cycling life by up to 40% compared to standard bump distributions.

Technical Capabilities

OurPCB’s flip chip packaging solution delivers exceptional technical capabilities across all critical parameters. Our placement systems achieve alignment accuracy down to 0.5μm, ensuring perfect registration between die and substrate. This precision extends to components with pitches as small as 100μm, supporting the most demanding miniaturization requirements. Our proprietary bonding profile optimization system ensures ideal temperature and pressure parameters for each unique component combination, significantly reducing stress-related failures.

Our comprehensive flip chip capabilities extend beyond basic bonding to include specialized applications such as optical alignment for photonic devices, 3D packaging configurations, and multi-chip modules. We maintain strict process controls for all critical parameters including temperature profiles, pressure application, and alignment verification.