Dose and image quality
Balance optical efficiency with contrast, feature transfer, edge behavior, and usable depth of focus.
DMD maskless lithography opticsPalo Alto, California
DIRECT IMAGING / DMD / PROJECTION
DMD projection optics engineered around dose, resolution, field, and throughput.
PAO develops maskless exposure optical engines from source coupling and DMD illumination through projection, focus, calibration, and production-ready optomechanics.
SYSTEM WORKFLOWPAO / 01
01UV source
02Homogenizer
03DMD
04Projection optics
05Substrate
For PCB, advanced packaging, microfabrication, and application-specific direct imaging.
01Engineering reality
A DMD engine is a coupled radiometric and imaging system.
Pixel mapping, source etendue, DMD state contrast, projection NA, distortion, focus, thermal load, scan or stitching strategy, and resist response all affect the usable process window.
Field and registration
Control distortion, magnification, focus surface, pixel mapping, stitching, and stage-to-optics calibration.
Thermal and lifetime behavior
Manage source heat, spectral stability, contamination, DMD loading, and alignment drift over duty cycle.
02Project fit
PAO is the right fit when a DMD engine must meet both image quality and production constraints.
Best for teams ready to close process decisions around dose, mapping, source spectrum, and calibration into one controlled optical-engine program.
Process targets are clear but the architecture is unresolved
Feature size, dwell, dose, resist, and throughput are known, but source-to-projection coupling and mapping strategy are still open.
Uniformity, registration, or yield is unstable
Field roll-off, stitching mismatch, distortion drift, or thermal-induced drift is reducing repeatability during prototype runs.
You need supplier-ready transfer
A bench build exists, but procurement is blocked by missing tolerances, calibration maps, test conditions, and issue-tracking format.
ENGINEERING DECISION TABLE
Inputs that change the architecture, acceptance method, and program risk.
| Input condition | Key metric | Design choice | Risk if unresolved |
|---|---|---|---|
| Feature and throughput target | Minimum resolvable feature, cycle time, dose uniformity | Line-imaging versus projection mode, NA, zoom strategy, source and duty settings | Throughput can increase while critical pitch quality degrades. |
| Source and process chemistry | Spectral response, conversion efficiency, contrast, aging | LED or LD architecture, band set, thermal control, monitoring points | Incorrect source strategy can hide process drifts and overpromise stability. |
| Calibration and mapping path | Pixel mapping error, distortion residual, registration repeatability | Mapping grid, correction order, distortion model, reference artifact | Acceptance may fail during stage transitions or production setup changes. |
| Procurement and production readiness | Supplier lead time, qualification scope, test method consistency | Controlled BOMs, drawings, optical/mechanical package, release criteria | The prototype cannot be converted to reliable pilot manufacturing. |
SELECTED ENGINEERING EVIDENCE
Published scope, verification method, and disclosure boundary.
These records describe documented engineering experience or the evidence plan PAO uses for new work. They do not imply that prior-employer programs were PAO customer engagements.
DMD projection architecture evidence
- Scope
- Typical DMD architecture and interface stack including illumination strategy, projection layout, and integration interfaces.
- Verification
- Feature transfer and uniformity are closed against defined process conditions and measurable acceptance limits.
- Boundary
- Specific customer results, exact dimensions, and supplier identities are not published.
Delivery framework for new PAO work
- Scope
- Requirements trace, source mapping, calibration plan, change control, acceptance evidence, supplier handoff format.
- Verification
- Decision gates include defined input assumptions, measurement conditions, and pass/fail criteria before supplier transfer.
- Boundary
- Performance promises are only confirmed after requirements completion and acceptance confirmation.
03Engineering scope
Engineering from the source package to the resist plane.
The optical engine is developed against the actual exposure process rather than treated as an isolated projection lens.
Define a technical work packageProcess and pixel budget
Feature target, resist sensitivity, pixel scale, magnification, overlap, throughput, and focus allocation.
Source and illumination
LED or laser-diode coupling, spectral selection, fly-eye or light-pipe homogenization, pupil fill, and radiometry.
DMD integration
Device format, tilt geometry, illumination angle, contrast paths, window effects, cooling, and mechanical interface.
Projection optics
Magnification, NA, modulation transfer, distortion, telecentricity, focus surface, and chromatic control.
Calibration strategy
Pixel-to-stage mapping, geometric correction, uniformity correction, autofocus interface, and image verification.
Build and transfer
Precision mounting, alignment sequence, tolerance model, optical acceptance, and supplier-ready release.
04Reference hardware
Real optical-engine starting points, adapted to the customer process.
These configurations demonstrate available delivery pathways. PAO defines the production requirement, system interfaces, calibration, verification, and changes needed for the intended application.
REFERENCE ARCHITECTURE / LINE IMAGING
405 nm DMD direct imaging
A configurable optical-engine starting point for line-layer exposure. PAO adapts the architecture, interfaces, calibration, and acceptance plan to the customer's process.
- Wavelength
- 405 nm
- Optical range
- 1.3x to 2.7x
- Feature class
- 15 to 50 um reference
REFERENCE ARCHITECTURE / SOLDER MASK
Mixed-wavelength DMD exposure
A source-flexible engine architecture for solder-mask and substrate applications requiring process-specific spectral and thermal design.
- LED options
- 365/385 nm
- LD band
- 375 to 440 nm
- Process class
- 50 to 150 um reference
05Technical envelope
Architecture options for direct-imaging processes.
Representative capability is shown with the context needed to qualify it. Program requirements control the final architecture and acceptance values.
PCB line imaging
Projection architectures for fine line and space patterning with controlled field mapping and focus.
Solder-mask exposure
Mixed-wavelength or application-tuned UV delivery for photosensitive solder-mask processes.
Advanced packaging
Maskless exposure for substrates, redistribution-related processes, and specialized microfabrication steps.
Custom direct imaging
Purpose-built DMD engines for research, additive, patterning, curing, and machine-integrated applications.
REFERENCE ENVELOPE
Line-imaging reference405 nmRepresentative direct-imaging architecture
Projection range1.3x to 2.7xReference platform envelope; project design may differ
Published feature class15 to 50 umProcess-dependent reference, not a guaranteed resolution
Solder-mask sources365/385 nm LED or 375 to 440 nm LDSelected against resist and dose requirements
Published process class50 to 150 umReference envelope for solder-mask applications
The values above describe representative platform envelopes. Feature transfer depends on resist, substrate, dose, contrast, focus, motion, calibration, and acceptance method; final performance is defined and verified per program.
06What you receive
Engineering outputs your team can review, build, test, and maintain.
The exact package follows the program stage and scope. Assumptions, interfaces, decisions, and acceptance evidence remain visible.
Exposure architecture
Source-to-substrate optical layout, power budget, pixel budget, interfaces, and risk register.
Illumination design
Source coupling, homogenizer, relay, pupil control, filters, thermal inputs, and irradiance model.
Projection design
Lens prescription, magnification, MTF, distortion, telecentricity, focus, and tolerance analyses.
Calibration definition
Mapping, distortion and uniformity correction, focus procedure, artifacts, and data products.
Engine integration package
DMD, optical, mechanical, thermal, stage, controls, and service interfaces.
Prototype-to-production support
Build oversight, alignment, test correlation, issue closure, and configuration-controlled release.
07Controlled delivery
A local engineering interface from first review through release.
PAO leads the technical work, coordinates specialized fabrication and production resources under the project quality process, and keeps responsibility for requirements, interfaces, evidence, and issue closure clear.
- 01
Technical intake
Define the system boundary, decision to be made, current evidence, constraints, and confidentiality path.
- 02
Requirements and risk
Create measurable requirements, interface assumptions, performance budgets, and a ranked technical risk register.
- 03
Architecture and proof
Compare viable concepts and retire the highest-risk assumptions with analysis, breadboards, or targeted tests.
- 04
Detailed engineering
Develop controlled optical, mechanical, calibration, test, and supplier-ready documentation.
- 05
Build and verification
Support procurement, assembly, alignment, test correlation, root cause, and evidence-based iteration.
- 06
Release and transfer
Close acceptance criteria, configuration, supplier questions, manufacturing issues, and production handoff.
08Qualification questions
Questions engineering teams ask before engaging.
01Do you provide only a projection lens or the complete optical engine?
Either scope is possible. For lower integration risk, PAO typically defines source, illumination, DMD, projection, optomechanics, calibration, and test as one controlled subsystem.
02Can one architecture support multiple wavelengths?
Potentially, but coatings, materials, focus, source etendue, detector response, and resist sensitivity must be evaluated together. A wavelength choice should be treated as a system trade, not a component substitution.
03What determines achievable feature size?
Pixel scale, projection NA, aberrations, contrast, focus, vibration, dose, resist behavior, substrate flatness, motion, and image processing all contribute. PAO establishes a traceable budget and verification method for the target process.
10Start a conversation
Define the process window before selecting the engine.
Send the feature, field, resist, wavelength, dose, working distance, and throughput targets available today. Unknowns can be handled as explicit trades.