Dam & Fill
Precision dam and fill dispensing for selective area encapsulation in semiconductor packaging — protecting specific zones of SiP modules, mixed-component substrates and hybrid circuits while leaving others exposed.
Selective Area Protection with Dam and Fill Dispensing
Dam and fill is a two-stage dispensing process used wherever a semiconductor package or hybrid module requires selective area encapsulation — protecting specific components or zones while leaving others, such as connectors, optical windows, RF antennas or test points, completely free of encapsulant. The process first dispenses a higher-viscosity dam material that forms a containment wall around the target area, then fills the contained region with a lower-viscosity material that flows and self-levels to fully cover components within the boundary. This approach achieves precise selective protection that flood encapsulation methods cannot, since the dam physically prevents fill material from spreading beyond its intended footprint.
The dispensing challenge in dam and fill is selecting and dispensing two materials with carefully matched but distinct rheological properties — the dam material must be viscous enough to hold a defined wall shape immediately after dispensing and gel quickly enough to contain the fill material that follows, while the fill material must be fluid enough to flow around components and self-level within the dam boundary without voids. Dam wall height, width and gel timing must all be validated together with the fill material's flow characteristics to ensure the fill stays contained without overtopping the dam or leaving gaps at the dam-substrate interface.
SANCO desktop visual dispensing machines with dual-material dispensing configurations deliver the precise boundary control, sequential material dispensing and process timing management required for dam and fill encapsulation across SiP modules, hybrid circuits and mixed-function semiconductor packages.
Why Dam and Fill Demands Precise Two-Material Process Coordination
Dam and fill requires careful coordination between dam material rheology, fill material flow behaviour and process timing to achieve reliable selective area encapsulation.
Dam Material Shape Retention
The dam bead must hold its dispensed cross-sectional shape immediately after deposition, without slumping or spreading, until it gels sufficiently to contain the fill material. Material viscosity and thixotropy must be precisely matched to the dam height and width required for each application.
Dam-to-Fill Material Compatibility
Dam and fill materials must be chemically compatible at their interface — incompatible material pairs can result in poor adhesion between dam and fill, creating a leak path, or chemical interference that prevents proper cure of one or both materials.
Fill Material Containment Without Overtopping
Fill material volume must be calculated precisely relative to the dam-enclosed area and dam wall height, ensuring the fill level rises high enough to fully cover all components within the boundary without exceeding the dam height and spilling over.
Dam Wall Continuity at Corners and Junctions
Dam wall dispensing paths often include corners or T-junctions where multiple dam segments meet. Maintaining continuous, gap-free dam wall geometry at these junctions is critical — any gap allows fill material to escape the intended boundary.
Process Timing Between Dam and Fill Stages
The interval between dam dispensing and fill dispensing must be carefully controlled — too short and the dam has not gelled sufficiently to contain fill material; too long and production throughput suffers, or the dam material may over-cure and lose adhesion compatibility with the subsequently dispensed fill.
Multiple Isolated Zones on One Substrate
Complex SiP modules may require multiple separate dam and fill zones on a single substrate, each protecting a different functional area with potentially different fill materials — requiring sequential multi-zone programming and material switching within a single substrate's process cycle.
Key Capabilities for Dam and Fill Encapsulation
Dual-Barrel Sequential Dispensing
Independent barrel and valve configurations for dam and fill materials enable sequential dispensing within a single automated programme, eliminating manual material changeover between stages.
CCD Vision Boundary Programming ±0.1 mm
Vision-guided dam wall dispensing maintains precise boundary positioning relative to substrate features, ensuring the contained zone aligns accurately with the intended protection area.
Gel-Time Matched Process Sequencing
Programmable dwell time between dam and fill dispensing stages is calibrated to each material pair's gel characteristics, ensuring the dam is structurally ready to contain fill material when dispensing begins.
Continuous Dam Path at Corners & Junctions
Servo-controlled path interpolation maintains continuous dam bead cross-section through corners and T-junctions, eliminating the gaps that would allow fill material to escape the boundary.
Calculated Fill Volume per Zone
Fill material volume is calculated from the dam-enclosed area and target fill height for each isolated zone, ensuring complete component coverage without overtopping the dam wall.
Multi-Zone Programming for Complex Substrates
Single programme sequences multiple isolated dam and fill zones on one substrate, supporting complex SiP modules with several functionally distinct protected areas.
Substrate CAD Import for Boundary Generation
Import substrate CAD data to auto-generate dam wall paths and fill volumes for each protection zone, reducing NPI programming time for new SiP and hybrid module designs.
Inline SiP Assembly Integration
SMEMA-compatible conveyor integration links SANCO dam and fill equipment into automated SiP and hybrid module assembly lines between component placement and cure stations.
The Dam and Fill Process Step by Step
Dam and fill requires precisely sequenced dispensing of two materials with matched rheological properties. SANCO equipment manages the full process automatically.
Substrate Inspection & Boundary Setup
Substrate inspected and CCD vision establishes coordinate system. Encapsulation boundary and keep-out zones programmed for the specific substrate design.
Dam Wall Dispensing
High-viscosity dam material dispensed as a continuous wall around the protection zone perimeter, maintaining consistent cross-section through all corners and junctions.
Dam Gelation Dwell
Programmed dwell time, with optional UV exposure or brief thermal stage, allows the dam to gel sufficiently to structurally contain the fill material that follows.
Fill Material Dispensing
Lower-viscosity fill material dispensed within the dam boundary at a calculated volume, flowing and self-levelling to fully cover all components in the zone.
Cure & Boundary Verification
Fill material cured per specification. Inspection confirms fill remained within the dam boundary and keep-out areas outside the dam remain completely clear.
Dam and Fill Material Types & SANCO Compatibility
SANCO dispensing machines handle matched dam and fill material pairs used for selective area encapsulation in semiconductor and hybrid packaging.
| Material Type | Viscosity Range | Cure Method | Typical Application | SANCO Compatibility |
|---|---|---|---|---|
| High-Viscosity Dam Epoxy | 40,000 – 150,000 mPa·s | UV pre-gel + thermal final cure | Containment wall dispensing for selective encapsulation boundaries on SiP and hybrid module substrates | Recommended |
| Low-Viscosity Fill Epoxy | 2,000 – 15,000 mPa·s | Thermal 100–150°C | Self-leveling fill material for complete component coverage within dam-contained zones | Recommended |
| UV-Gel Dam Material (Fast Process) | 30,000 – 100,000 mPa·s | UV 365 nm, 5–15 s gel | Rapid-gelling dam material for high-throughput dam and fill lines requiring minimal dwell time between stages | Recommended |
| Thermally Conductive Fill Compound | 5,000 – 25,000 mPa·s | Thermal 100–150°C | Fill material with thermal conductivity for zones containing power components requiring heat dissipation within the protected area | Recommended |
| Low-Stress Silicone Fill | 1,000 – 10,000 mPa·s | Thermal 100–150°C | Stress-sensitive fill material for zones containing MEMS or pressure-sensitive components within a dam-contained area | Recommended |
Frequently Asked Questions
How does SANCO determine the correct dwell time between dam and fill dispensing?
The dwell time is calibrated during process development based on the specific dam material's gel characteristics — typically determined by dispensing test dam beads and measuring the time required to reach sufficient structural integrity to contain a test fill material without slumping. This dwell time is then programmed as a fixed parameter in the production dispensing sequence. Contact our application engineers for dam and fill material pair qualification support.
Can SANCO maintain continuous dam wall geometry through corners on complex substrate boundaries?
Yes. SANCO dispensing machines use servo-controlled path interpolation that maintains constant linear dispensing speed and consistent bead cross-section through corners and direction changes, preventing the thin spots or gaps at corners that would otherwise allow fill material to escape the dam boundary.
How does SANCO calculate fill material volume for dam-enclosed zones?
Fill volume is calculated from the dam-enclosed area (determined by the programmed dam wall path) multiplied by the target fill height, with the target height set below the dam wall height by a safety margin to prevent overtopping. This calculation is validated during process qualification by measuring actual fill level after dispensing on test units.
Can SANCO machines handle multiple isolated dam and fill zones on a single substrate?
Yes. SANCO dispensing programmes support sequential processing of multiple isolated zones on one substrate within a single automated cycle, including material switching between zones if different fill materials are required for different functional areas of a complex SiP module.
What happens if dam material is dispensed but fill material leaks through a gap?
This is why dam wall continuity verification is built into SANCO's process — vision inspection after dam dispensing can verify wall continuity before fill dispensing begins, and post-fill inspection confirms the fill remained within boundaries. Catching dam integrity issues before fill dispensing prevents scrap from fill material escaping into keep-out zones.
Where can I learn about other semiconductor packaging dispensing applications?
Visit our Applications section for guides covering die attach dispensing, chip package encapsulation, wafer-level packaging and glob top protection processes. For equipment specifications, see our dispensing machine product pages.
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