Process Overview
Producing microfluidic chips from borosilicate glass requires a disciplined sequence that begins with high-quality raw material and ends with fully inspected, ready-to-integrate components. Our process leverages cold laser ablation to etch fine channel geometries without compromising the glass matrix, followed by thorough cleaning, optional thermal bonding, and comprehensive optical inspection.
Material Preparation
Sheets of borosilicate glass are selected for flatness, transmission properties, and chemical durability. Using scribe‑and‑break or abrasive waterjet cutting, we size substrates to carrier dimensions. Edge finishing is then performed with precise CNC grinding to remove micro‑chips and ensure safe handling—a step detailed in our CNC Glass Grinding Process for Tight Tolerance Parts.
Laser Etching Process
Channel features are formed with ultra‑short pulse lasers, typically femto‑second duration. This “cold ablation” mechanism removes material faster than heat can diffuse, leaving an athermal cut with no heat‑affected zone and intrinsically low surface roughness. The process supports a variety of geometries, including straight, curved, tapered, and complex 3D structures like helical mixers.
Geometric Capabilities
- Channel widths from 10 µm to 500 µm with positional accuracy ±0.5 µm.
- Surface roughness below 20 nm Ra [VERIFY].
- Aspect ratios up to 10:1, depending on substrate thickness [VERIFY].
Cleaning and Surface Preparation
Post‑etching, chips undergo multi‑stage cleaning in ISO‑rated cleanrooms. This includes chemical baths to lift residues and high‑purity rinses that leave surfaces chemically pristine, ready for bonding or direct use.
Channel Sealing and Bonding (Optional)
For closed‑channel designs, cleaned glass layers are aligned and thermally fusion‑bonded at approximately 600°C. The resulting monolithic bond creates hermetic seals capable of withstanding pressures above 150 bar [VERIFY] without adhesives or intermediate layers.
Inspection and Quality Control
Every chip is inspected with optical microscopy, profilometry, and automated optical inspection (AOI) systems. Key checks include channel dimensions, surface finish, and bond integrity. When specified, we conduct leak‑testing and pressure‑decay evaluations to confirm seal performance.
Packaging and Export Preparation
Inspection‑passed chips are placed in cleanroom‑compatible trays, gel packs, or vacuum‑sealed pouches. Packaging is often performed under nitrogen to maintain cleanliness, and each unit is labeled for full traceability. Export documentation is prepared in accordance with international shipping regulations.
Process Flow Table
| Process Step | Key Action | Critical Control | Risk Mitigation |
|---|---|---|---|
| Material Preparation | Cut and edge‑grind borosilicate substrates | Dimensional accuracy, edge quality | CNC grinding with post‑process inspection |
| Laser Etching | Femto‑second laser ablation of channel geometry | Pulse energy, scan path, focal position | In‑process beam monitoring, periodic test coupons |
| Cleaning | Multi‑stage chemical rinse and dry | Particulate and organic residue levels | ISO class environment, verified wash protocols |
| Bonding (Optional) | Thermal fusion bonding in controlled atmosphere | Temperature ramp, alignment, pressure | Pre‑bond inspection, post‑bond acoustic microscopy |
| Inspection | Optical, profilometric, and leak testing | Channel dimensions, surface roughness, seal integrity | Statistical sampling, calibrated instruments |
| Packaging | Cleanroom‑compatible packing and documentation | Particle control, traceability | Nitrogen purge, label verification |
Common Risk-Control Notes
- Micro‑fracture risk: Mitigated entirely by the athermal nature of femto‑second ablation, avoiding mechanical stress introduction.
- Subsurface damage: Non‑existent; laser‑material interaction is confined to an extremely shallow volume.
- Particulate contamination: Controlled through cleanroom protocols and validated cleaning sequences that leave surfaces below specified particle counts.
- Bond voids: Minimized by pre‑bond flatness verification and controlled thermal profiles; inspected with scanning acoustic microscopy.
- Channel consistency: Maintained through regular laser power calibration and process limit charts for critical dimensions.
Frequently Asked Questions
What are the smallest practical channel widths you can deliver?
Production‑ready channels start at 10 µm width, held to a positional tolerance of ±0.5 µm. For specialized designs, narrower channels may be possible—please consult our engineering team.
Can you etch channels on both faces of the wafer?
Yes, double‑sided processing is routinely performed. Through‑glass vias and multi‑layer alignment marks are also within capability.
How do you guarantee hermetic sealing at high pressures?
We use direct thermal fusion bonding, which chemically fuses the glass layers into one monolithic structure. Leak testing up to 150 bar [VERIFY] is available to confirm seal integrity.
What design constraints should I keep in mind?
Channel aspect ratio, bend radii, and inlet/outlet placement influence manufacturability. For detailed guidelines, refer to our Design Rules for Reliable Glass Microfluidic Channels.
What is a typical lead time for prototype quantities?
Lead times depend on design complexity and current production load, but standard prototypes are often delivered within 3–4 weeks. Rush services may be available—contact us with your specifications.