QWR Interactive Solutions · Engineering Reference
Design for Manufacturing Guide
Hardware guidelines for partners, OEMs, and developers building with QWR. Covers electronics, mechanical enclosures, XR optics, and material specifications — from prototype to production.
4
Sections
Rev 1.0
Version
02 Apr 2026
Last Updated
Active
Status
Section 01
PCB & Electronics
Layout rules, component clearances, signal integrity, and testability requirements. All PCBs must conform before fabrication. Deviations require written sign-off from QWR Engineering.
Board Specifications
| Parameter | Minimum | Recommended | Notes |
|---|---|---|---|
| Min trace width | 0.1 mm | 0.15 mm | Signal traces; power traces per IPC-2221 |
| Min trace spacing | 0.1 mm | 0.15 mm | Increase for high-voltage rails (>50 V) |
| Min via drill | 0.2 mm | 0.3 mm | Micro-vias require DFM review |
| Min annular ring | 0.125 mm | 0.15 mm | All drill classes |
| Board thickness | 0.6 mm | 1.0 mm | XR form-factor targets: 0.8 mm |
| Copper weight (outer) | 1 oz | 1 oz | 2 oz for power stages |
| Edge clearance | 0.3 mm | 0.5 mm | All copper from board edge |
Component Placement
Keepout zones
Maintain a 3 mm component-free keepout on all board edges. Connectors are exempt only if deliberately edge-mounted.
Heatsink clearance
No components taller than 0.5 mm within 2 mm of any active heatsink or thermal pad footprint.
SMD orientation uniformity
Align passive components in consistent orientations to optimise the reflow profile and reduce tombstoning risk.
Decoupling placement
Place decoupling capacitors within 0.5 mm of IC power pins.
Test point coverage
Expose all key power rails and I²C/SPI/UART buses via labelled test points.
Fiducial markers
Include a minimum of 3 fiducials at board corners for SMT pick-and-place.
Signal Integrity
USB 3.0, MIPI, and LVDS pairs must be length-matched within 2 mil. Route on the same layer.
Specify controlled impedance stackup in fab notes. 50 Ω single-ended, 90 Ω differential for USB.
Pre-Submission Checklist
- Design Rule Check (DRC) passes with zero errors in KiCad / Altium
- All component footprints verified against physical datasheet land patterns
- BOM exported with MPN, manufacturer, and approved alternatives flagged
- Gerber, drill, and IPC-D-356 netlist packaged for fab
Section 02
Enclosure & Mechanical Design
Wall thickness, draft angles, assembly strategy, and fastener standards for injection-moulded and CNC-machined enclosures across QWR product lines.
Injection Moulding
| Parameter | Value | Notes |
|---|---|---|
| Nominal wall thickness | 1.5 – 2.5 mm | Uniform wall preferred |
| Min draft angle | 1° | 2° recommended for textured surfaces |
| Rib thickness | 50–60% of wall | Prevents sink marks on outer face |
| Min inside radius | 0.5 mm | At wall junctions |
| Snap-fit deflection | ≤ 2% | Of nominal beam length |
CNC Machining (Aluminium)
Min feature size
Min pocket width 1.0 mm, min hole diameter 0.5 mm. Tolerances tighter than ±0.05 mm require sign-off.
Chamfer vs fillet
Prefer chamfers on external edges; fillets on all internal corners.
Thread specification
M-series metric threads only. M2 minimum for structural fastening.
Surface finish callout
Include Ra value on drawing. Bare aluminium default: Ra 1.6 µm.
Design for top-down assembly where possible. QWR targets single-axis assembly for all sub-assemblies.
Fastener Standards
Approved fasteners
- M2 / M2.5 / M3 socket head cap screws (ISO 4762)
- M2 / M2.5 self-tapping for plastic bosses
- Heat-set inserts (M2+) for thermoplastic boss reuse
Not permitted
- Imperial fasteners (UNC/UNF) — metric only
- Adhesive-only structural joints
- Custom fastener profiles without DFM review
Section 03
XR Optics & Display Constraints
XR optics are the highest-precision component class in any QWR product. Tolerances are an order of magnitude tighter than standard mechanical parts.
Display Panel Requirements
| Parameter | Specification |
|---|---|
| Panel type | Micro-OLED / LCoS |
| Min PPI | 2000 PPI |
| Luminance (peak) | ≥ 5,000 nit |
| Colour gamut | ≥ 85% DCI-P3 |
| Refresh rate | 90 Hz minimum |
| Panel flatness | ≤ 10 µm bow |
Waveguide Design Rules
Waveguide substrates are designed and validated entirely by QWR. Do not alter grating period, substrate index, or coupling angles.
Incoupler position tolerance
In-coupling grating must be positioned within ±15 µm XY of nominal.
Waveguide-to-display gap
Air gap between display exit pupil and waveguide surface: 0.3 mm ± 0.05 mm.
Stray light baffling
Include light-absorbing baffles between illumination path and detector.
Waveguide handling
Handle only with clean-room gloves. No contact with grating surface.
Eye-Box & FOV Targets
| Parameter | Target | Minimum |
|---|---|---|
| Horizontal FOV | 40° | 30° |
| Eye-box (horizontal) | 12 mm | 8 mm |
| Eye relief | 18 mm | 14 mm |
| Uniformity (centre vs edge) | ≥ 70% | 60% |
All devices must pass QWR's optical qualification suite: MTF measurement, uniformity map, stray light scan, and eye-box cross-section.
Section 04
Materials & Tolerance Specifications
Material selection and tolerance callouts must be explicit on all engineering drawings submitted to QWR.
Approved Material Families
| Category | Approved Materials | Typical Use |
|---|---|---|
| Structural plastic | PC, PC/ABS, PA66-GF30 | Main enclosures, structural frames |
| Flexible / gasket | TPU 85A–95A, Silicone | Seals, nose pads, cable strain relief |
| Optical plastic | PMMA (optical grade), Zeonex | Lens elements, light pipes, diffusers |
| Metal (structural) | Al 6061-T6, Al 7075-T6, Ti Gr.5 | Machined frames, hinges, optic mounts |
| PCB substrate | FR-4, Rogers 4350B | Standard PCB, RF/mmWave boards |
Dimensional Tolerance Classes
TOLERANCE CLASS REFERENCE ──────────────────────────────────────────────────────────────── CLASS LINEAR TOLERANCE ANGULAR APPLICATION ──────────────────────────────────────────────────────────────── T1 — Coarse ± 0.5 mm ± 1.0° Non-mating cosmetic T2 — Medium ± 0.2 mm ± 0.5° Standard mating faces T3 — Fine ± 0.05 mm ± 0.1° Precision interfaces T4 — Optic ± 0.01 mm (10 µm) ± 0.02° Waveguide & lens seats T5 — Ultra ± 0.002 mm (2 µm) ± 0.005° Active optical alignment ──────────────────────────────────────────────────────────────── Default if unspecified: T2 | Optic mounts: T4 minimum
All T3, T4, and T5 features must carry explicit GD&T callouts per ASME Y14.5-2018.
Compliance & Certification Requirements
Required — all hardware
- RoHS 3 (EU 2015/863) compliance across full BOM
- UL94 V-0 or V-2 flame rating for enclosure plastics
- Material Safety Data Sheets (MSDS/SDS) on file
Required — consumer products
- CE marking (RED Directive for wireless devices)
- FCC Part 15B / Part 15C (US market)
- BIS certification (India market)
Strictly prohibited in any QWR-manufactured product: hexavalent chromium, cadmium, lead (except exempted solder per RoHS Annex III), mercury, PBB, PBDE.
Documentation Required at Design Freeze
- Complete BOM with MPN, manufacturer, material grade, and RoHS status
- Engineering drawings for all custom parts — GD&T per ASME Y14.5-2018
- 3D STEP or Parasolid files for all mechanical components
- Compliance declarations: RoHS, REACH, UL94 flame class
See how QWR handles customisation and manufacturing at scale.