Why Specification Sheets Matter
A comprehensive specification sheet is the foundation for successful graphic overlay procurement, serving as the single source of truth that aligns design intent, manufacturing requirements, quality expectations, and inspection criteria.
Clear, complete specifications prevent misunderstandings, reduce manufacturing errors, accelerate quote turnaround, and ensure that delivered parts meet functional and aesthetic requirements on the first production run.
This guide explains what to include in overlay specification sheets and provides a structured template to ensure nothing is overlooked during the specification process.
Essential Information for Overlay Specifications
Every overlay specification sheet should begin with basic identifying information and project context that helps suppliers understand the application and prioritize requirements.
Header Information
- Part Number: Unique identifier (e.g., "GO-2024-001-RevB").
- Revision Level: Track changes over time (A, B, C…); document change history.
- Date Issued: Date of current revision.
- Prepared By: Contact person name, title, email, phone.
- Company Name and Project: Customer identification and application context.
- Confidentiality Notice: If applicable, mark proprietary or confidential.
Application Context
Brief description of application environment and usage helps suppliers recommend appropriate materials and processes.
- End Use: Medical device, industrial control, automotive dashboard, consumer appliance, etc.
- Operating Environment: Indoor/outdoor, temperature range, humidity, UV exposure, chemical contact.
- Expected Service Life: Product lifetime and typical use frequency.
- Regulatory Requirements: FDA, UL, RoHS, REACH, automotive standards, etc.
Quantity and Delivery Information
- Prototype Quantity: Number of samples for validation (typically 5–25 pieces).
- Production Quantity: Annual volume or order quantities (e.g., 5,000/year, orders of 500–1,000 pcs).
- Lead Time Requirements: Prototype turnaround and production lead time expectations.
- Packaging: Individual bags, bulk trays, protective liners, custom packaging.
Material Specifications and Requirements
Material selection directly impacts overlay performance, durability, and cost; clearly specifying materials prevents substitutions that compromise quality.
Substrate Film
| Specification Item | What to Specify | Example |
|---|---|---|
| Material Type | Polyester (PET), polycarbonate (PC), polyimide, vinyl, etc. | Polyester (PET) |
| Thickness | Nominal thickness with tolerance (typically ±10%) | 0.25mm ±0.025mm |
| Surface Finish | Glossy, matte, textured, anti-glare, etc. | Matte finish, 3H hardcoat |
| Color/Clarity | Clear, white, tinted; light transmission if relevant | Clear, >90% light transmission |
| Special Properties | UV-stable, flame-retardant (UL94), anti-static, etc. | UV-stabilized, UL94 V-0 |
| Material Certifications | RoHS, REACH, FDA, UL listing, etc. | RoHS compliant, UL recognized |
Adhesive
- Adhesive Type: Acrylic PSA, rubber-based, silicone, epoxy, etc.
- Coverage Pattern: Full-surface, perimeter only, selective areas (provide drawing or description).
- Peel Strength: Minimum peel force (e.g., ≥1,000 g/25mm per ASTM D3330).
- Temperature Range: Adhesive must maintain bond strength across operating range (e.g., -40°C to +85°C).
- Surface Compatibility: Intended bonding surface (painted metal, textured plastic, glass, etc.).
- Removability: Permanent bond or removable/repositionable if required.
Protective Coatings
- Hard Coat: Pencil hardness rating (e.g., 3H, 4H) per ASTM D3363.
- Anti-Fingerprint: Oleophobic coating if needed.
- Chemical Resistance: Specify test chemicals and exposure duration (e.g., isopropyl alcohol, 10,000 wipes).
Dimensional Data and Tolerances
Precise dimensional specifications ensure overlays fit correctly in assemblies and align with switches, displays, and mounting features.
Engineering Drawing Requirements
- Overall Dimensions: Length, width with tolerances (e.g., 150.0mm ±0.2mm × 75.0mm ±0.2mm).
- Thickness: Total stack-up thickness including substrate, adhesive, and liners.
- Feature Locations: Holes, cut-outs, windows dimensioned from defined datum edges or center points.
- Radii: Corner radii and internal cut-out radii specified (minimum radius typically ≥1.0mm).
- Reference Dimensions: For information only; clearly marked "REF" or in parentheses.
General Tolerances
| Feature Type | Standard Tolerance | Tight Tolerance (if required) |
|---|---|---|
| Overall Length/Width | ±0.2mm | ±0.1mm |
| Hole/Cut-out Position | ±0.15mm | ±0.1mm |
| Hole/Cut-out Size | ±0.1mm | ±0.05mm |
| Corner Radii | ±0.2mm | ±0.1mm |
| Emboss Height | ±0.1mm | ±0.05mm |
Critical Dimensions
Identify features requiring tighter-than-standard tolerances and explain why (e.g., "Hole A must align with PCB mounting boss; tolerance ±0.1mm critical").
Avoid specifying unnecessarily tight tolerances, which increase cost without functional benefit.
Graphic Design and Artwork Requirements
Graphic specifications define color, legend content, and visual appearance; providing artwork in correct formats accelerates supplier quoting and production.
Color Specifications
- Pantone PMS Codes: Specify Pantone color with substrate designation (C, U, T) for each color.
- Color Tolerance: Acceptable Delta E (ΔE) variation (typically ΔE < 2.0 for brand-critical colors).
- Physical Swatches: If available, provide Pantone swatch book reference (e.g., "Pantone 2021 Formula Guide Coated").
- Viewing Conditions: Specify illuminant for color evaluation (typically D65 daylight).
Artwork File Formats
- Vector Files Preferred: Adobe Illustrator (.AI), PDF, or EPS for scalability and print clarity.
- Layer Organization: Separate layers for each print color, cut lines, emboss areas, windows, adhesive zones.
- Resolution: Raster images embedded at ≥300 DPI at final size.
- Fonts: Convert text to outlines/paths to avoid font substitution issues.
- Bleed and Safe Zones: Include 2–3mm bleed beyond cut lines; keep critical content inside safe zone.
Legend Content
- Legibility requirements (minimum font size, contrast ratio).
- Language(s) for multilingual overlays.
- Regulatory symbols or warnings that must appear (CE, UL, safety icons).
- Branding elements (logos, model numbers, serial number fields).
Special Graphic Features
- Embossing: Specify embossed areas, height (typically 0.3–0.8mm), and button profiles.
- Windows: Clear areas for displays, LEDs, or sensors; light transmission requirements.
- Textures: Matte, gloss, soft-touch, or custom textures.
- Metallic or Special Effects: Metallic inks, holographic foils, dead-front designs.
Quality Standards and Acceptance Criteria
Clear quality standards define what constitutes acceptable vs. defective parts, reducing subjective interpretation and preventing disputes.
Visual Inspection Criteria
| Defect Type | Acceptable Limit |
|---|---|
| Scratches (visible at arm's length) | None in viewing area; max 2 per part in non-critical zones, each <10mm length. |
| Contamination (dust, ink spots) | None >0.5mm diameter in viewing area; max 3 per part <0.3mm in non-critical zones. |
| Bubbles or Delamination | None visible; edges must be fully bonded with no lifting. |
| Color Variation | ΔE < 2.0 for critical colors; ΔE < 3.0 for non-critical. |
| Legend Clarity | All text and symbols legible; no broken lines or smudges. |
| Cut Edge Quality | Clean, smooth edges; no fraying, burrs, or rough spots. |
Performance Testing Requirements
- Adhesion Testing: Minimum peel strength (ASTM D3330); adhesion after environmental exposure.
- Abrasion Resistance: Minimum cycles or rating (e.g., Taber CS-10 wheels, 1,000 cycles, <10% haze increase).
- Environmental Durability: Temperature cycling, humidity, UV exposure per relevant standards.
- Chemical Resistance: No visible damage after exposure to specified chemicals and durations.
Sampling and Inspection Plans
- AQL (Acceptable Quality Level): Define sampling plan (e.g., ANSI/ASQ Z1.4, AQL 1.5 Major, 2.5 Minor).
- First Article Inspection: Requirement for dimensional and functional verification of initial production samples.
- In-Process Inspection: Frequency of process checks (e.g., every 100 parts or hourly).
Specification Sheet Template and Checklist
Use this structured template to ensure all critical information is included in your overlay specification sheets.
Specification Sheet Template
GRAPHIC OVERLAY SPECIFICATION SHEET
Part Number: ____________________ Revision: ___ Date: __________
Prepared By: ____________________ Company: ____________________
Project/Application: ____________________________________________________
1. Application Context
- ☐ End Use: _______________________________________________________________
- ☐ Operating Environment: Temperature ___°C to ___°C, Humidity ___%, UV Exposure: Yes/No
- ☐ Expected Service Life: __________ years
- ☐ Regulatory Requirements: ________________________________________________________
2. Quantity and Delivery
- ☐ Prototype Quantity: __________
- ☐ Production Volume: __________ per year / per order
- ☐ Lead Time: Prototype: ____ weeks, Production: ____ weeks
3. Material Specifications
- ☐ Substrate: Material ____________, Thickness ______mm ±______mm
- ☐ Surface Finish: Gloss / Matte / Textured / Hard Coat (specify hardness: ____)
- ☐ Adhesive: Type ____________, Coverage: Full / Perimeter / Selective
- ☐ Certifications Required: RoHS / REACH / UL / FDA / Other: __________________
4. Dimensional Requirements
- ☐ Overall Dimensions: ____mm × ____mm (± tolerances per drawing)
- ☐ Critical Features: (list and specify tight tolerances if needed)
- ☐ Engineering Drawing Attached: Yes / No (Drawing Number: __________)
5. Graphic Design
- ☐ Pantone Colors: (list all colors with C/U/T designation)
- ☐ Color Tolerance: ΔE < ______
- ☐ Artwork Files: Format ________, Attached: Yes / No
- ☐ Special Features: Embossing / Windows / Metallic Inks / Other: ______________
6. Quality Standards
- ☐ Visual Inspection: Per attached criteria / Industry standard
- ☐ Performance Testing Required: (list tests and standards)
- ☐ AQL: __________ (Major / Minor)
- ☐ First Article Inspection: Required / Not Required
7. Additional Notes
______________________________________________________________________
______________________________________________________________________
Pre-Submission Checklist
- ☐ All header information complete and current
- ☐ Application context and environment clearly described
- ☐ Material specifications include thickness, finish, adhesive, certifications
- ☐ Engineering drawing attached with all dimensions and tolerances
- ☐ Artwork files provided in correct format with organized layers
- ☐ Pantone colors specified with substrate designation (C/U/T)
- ☐ Quality standards and acceptance criteria defined
- ☐ Performance testing requirements listed with standards referenced
- ☐ Quantity and lead time expectations stated
- ☐ Contact information for questions or clarifications included
Frequently Asked Questions
What file formats should I provide for artwork?
Vector formats (Adobe Illustrator, PDF, EPS) are preferred for scalability and print clarity. Organize artwork in layers (one per print color, plus cut lines, emboss, windows, adhesive zones).
Convert text to outlines to avoid font substitution issues.
How tight should dimensional tolerances be?
Standard tolerances (±0.2mm overall, ±0.15mm holes) are adequate for most applications and cost-effective. Specify tighter tolerances (±0.1mm or tighter) only for critical fit features.
Unnecessarily tight tolerances increase cost without functional benefit.
Do I need to specify adhesive if the overlay will be mechanically attached?
If the overlay uses clips, screws, or other mechanical attachment without adhesive, clearly state "No adhesive required" or "Mechanical attachment only" to avoid confusion.
If temporary positioning adhesive is acceptable, specify removable/repositionable type.
What quality standards should I reference?
Common standards include ISO 2859 or ANSI/ASQ Z1.4 for sampling plans (AQL), ASTM D3330 for adhesion, ASTM D1044 for abrasion, and MIL-STD-810 for environmental testing.
Reference industry-specific standards (UL, FDA, automotive) if applicable to your product.