Panel-Level Packaging (PLP) / Advanced Packaging Photoresist Coatings for Semiconductor Panel Formats
As advanced packaging moves from wafer-level to larger panel-level formats, traditional spin coating becomes increasingly impractical for achieving uniform photoresist coverage across large rectangular substrates. Sono-Tek ultrasonic spray coating systems provide a precise, scalable solution for depositing highly uniform photoresist films on panel level packaging substrates used in fan-out packaging, redistribution layer (RDL), and advanced semiconductor packaging processes.
Sono-Tek’s ultrasonic spray technology applies controlled, thin photoresist layers across full panel surfaces, package sites, vias, traces, and complex topography with excellent material efficiency. By replacing spin coating with a non-contact ultrasonic spray process, manufacturers can reduce photoresist waste, improve coating consistency, and support reliable photolithography across larger panel formats where uniformity and repeatability are critical.
Photoresist for Panel-Level Packaging
Panel-level packaging requires precise photoresist deposition across large-area substrates containing hundreds or thousands of individual package sites. Sono-Tek systems apply uniform photoresist coatings over redistribution layers, bonding pads, dielectric surfaces, and patterned features to support accurate lithography steps during advanced packaging production.
The ultrasonic spray process enables consistent coating thickness across the full panel while reducing pooling, streaking, and edge-related defects that can occur with conventional coating methods. This is especially valuable for large rectangular panels where spin coating can create significant material waste and non-uniform film distribution.
Fan-Out and RDL Processing
In fan-out panel level packaging, photoresist is commonly used to pattern redistribution layers, vias, and interconnect structures. Sono-Tek ultrasonic spray coating systems provide controlled deposition over complex panel topographies, helping maintain film continuity across raised and recessed features.
The soft, low-velocity spray produced by Sono-Tek’s ultrasonic nozzles supports uniform coverage without flooding fine structures, enabling reliable photoresist performance through exposure, development, and subsequent metal deposition or etch processes.
Large-Area Substrate Coating
Panel-level packaging substrates are often much larger than traditional wafers, making photoresist uniformity and material efficiency especially important. Sono-Tek systems are designed to coat large rectangular panels with repeatable motion control, precise liquid delivery, and high transfer efficiency.
This approach allows manufacturers to scale coating recipes from process development to production while maintaining consistent film thickness, strong adhesion, and reduced chemical consumption.
Advanced Packaging Process Integration
Sono-Tek’s panel-level packaging coating systems can be configured for cleanroom environments and integrated into advanced packaging workflows. Our systems support photoresist solvent blends, dielectric-compatible coating materials, and process recipes tailored to customer-specific substrates and panel formats.
From R&D and pilot production to automated in-line manufacturing, Sono-Tek platforms provide the flexibility needed to support evolving advanced packaging requirements, including fan-out packaging, heterogeneous integration, chiplet packaging, and next-generation microelectronics.
Technical Advantages
- Uniform photoresist deposition across large rectangular panel substrates
- Scalable alternative to spin coating for panel level packaging
- High material transfer efficiency, reducing photoresist and solvent waste
- Controlled coating thickness across RDL features, vias, pads, and package sites
- Soft, low-velocity ultrasonic spray that minimizes pooling and streaking
- Excellent adhesion and repeatability across complex panel topography
- Compatible with cleanroom production environments
- Scalable from process development to automated production systems
Sono-Tek Ultrasonic Nozzle Technology
The heart of Sono-Tek’s panel-level packaging coating systems is our patented ultrasonic spray nozzle, which uses high-frequency sound vibrations to create a soft mist of precisely controlled droplets. Because atomization is generated ultrasonically rather than through pressure, the spray is gentle, highly uniform, and non-clogging.
This narrow droplet distribution and low-velocity spray enable controlled photoresist deposition across large-area substrates, helping advanced packaging manufacturers achieve consistent film quality, reduced waste, and reliable process performance.
Talk to an Applications Engineer
Tell us about your panel-level packaging process. Our team will help you optimize photoresist coating uniformity, film thickness, adhesion, and material utilization across large-area substrates and complex package topographies, while recommending the ideal ultrasonic spray system for your production requirements.