IDB-PDS-001
Product definition · Engineering brief
Product definition and specification
Reference for defining a hardware product and writing the specification sheet that engineering and suppliers will quote against.
Abstract
Two adjacent deliverables: the product definition (intent, constraints, risk questions) and the product specification sheet (the technical attachment that goes with every RFQ, sample order, and supplier contract).
Section 1 captures intent. Section 2 captures engineering constraints. Section 3 surfaces risk questions. Section 4 covers the spec-sheet structure that the companion XLSX template (product-spec-sheet-template.xlsx) implements as fillable fields.
1.Product intent
Capture what the product is for and who it is for before any technical or commercial decisions are committed.
TARGET USER
specific persona, not market segment
USE ENVIRONMENT
drives sealing, materials, certifications
COMMERCIAL TARGET
retail price, manufacturing cost, volume
1.1Target user and context
- Target userSpecific persona. "Field technician working outdoors in cold weather" is usable; "professional users" is not.
- Use environmentIndoor desk, outdoor wet, vehicle dashboard, harsh industrial floor. Map to IP rating + temperature range + drop spec.
- Frequency of useDaily, occasional, emergency-only. Drives durability vs. reliability trade-off and warranty terms.
- Skill levelTechnical user, prosumer, mass-market consumer. Drives interface complexity and instructions.
1.2Commercial targets — pricing framework
Most consumer hardware sold through distribution follows a recognised retail markup multiplier. Pick the channel; the multiplier sets the cost ceiling.
| Channel | Multiplier on COGS | Example |
|---|---|---|
| Direct-to-consumer (DTC) | 2.0–2.5× | $20 product → $40–50 retail |
| Online marketplace (Amazon) | 2.5–3× | $20 COGS → $50–60 retail (after fees) |
| Specialty retail | 3–4× | $20 COGS → $60–80 retail |
| Mass retail (Target, Walmart) | 4–5× | $20 COGS → $80–100 retail |
| Premium / luxury | 5–10× | $20 COGS → $100–200 retail |
COGS includes: BoM + assembly labor + tooling amortisation + freight + duties + QC + warranty reserve (5–10 % of COGS).
1.3Function and scope
- Primary functionOne sentence. "Measures soil moisture and reports it over LoRa once an hour."
- Secondary functionsTwo or three that round it out. Mark each as "must" or "nice-to-have".
- Out of scopeWhat the product deliberately does not do. Saves more downstream time than any other line in the brief.
2.Engineering requirements
Define the lines the product must not cross. Each constraint is evaluated during prototyping and verified before tooling.
2.1Mechanical
- Enclosure material + grade
- Wall thickness target
- Surface finish (SPI/VDI codes)
- Colour (Pantone + sample chip)
- Sealing (IP rating + gasket)
- Drop / impact spec (height + class)
- Mounting interface
- Service access (battery, board)
2.2Electronics
- Power source + capacity
- Voltage rails (input + internal)
- Wireless module + bands
- Antenna type + position
- Display type + resolution
- Sensors + accuracy
- Connectors + mating cycles
- Firmware OTA / test mode
2.3IP rating reference (IEC 60529)
The two-digit IP code: IP[solids][liquids].
| Code | First digit (solids) | Second digit (water) |
|---|---|---|
| 0 | No protection | No protection |
| 1 | >50 mm objects | Dripping water |
| 2 | >12.5 mm objects | Dripping at 15° tilt |
| 3 | >2.5 mm objects | Spraying water |
| 4 | >1.0 mm objects | Splashing water |
| 5 | Dust-protected | Water jets |
| 6 | Dust-tight | Powerful water jets |
| 7 | — | Immersion ≤ 1 m for 30 min |
| 8 | — | Continuous immersion (depth specified) |
| 9K | — | High-temp/pressure jets |
Common ratings:
- IP54Indoor electronics, splash-resistant (handheld, smart-home, garden tools)
- IP65Outdoor electronics, dust-tight + water jets (security cameras, fitness wearables)
- IP67Submersion-resistant (some watches, ruggedised phones, sensors)
- IP68Continuous immersion (dive computers, professional outdoor)
- IP69KHigh-pressure cleaning (food service, industrial cleaning equipment)
2.4Drop spec by product class
| Class | Drop height | Surface | Reference |
|---|---|---|---|
| Tabletop | 0.76 m (30") | Hardwood / vinyl | IEC 60068-2-32 (free fall) |
| Handheld consumer | 1.0 m (40") | Concrete | IEC 60068-2-32 |
| Outdoor consumer | 1.2 m (48") | Concrete | MIL-STD-810H Method 516.8 |
| Rugged / industrial | 1.5 m (60") | Steel | MIL-STD-810H + IK rating |
| Mobile phone | 1.0 m (40") | 6 faces + 4 edges + 4 corners | Internal carriers ('phones) |
| Body-worn / sport | 1.0–1.5 m (40–60") | Concrete | IEC 60068-2-31 (tumble) + drop |
2.5Compliance constraints
- Target marketsEU, US, UK, Japan, Australia. Each adds a stack of directives.
- Applicable directivesCE (LVD, EMC, RED, RoHS, REACH), FCC, CPSIA, UL, RCM, PSE, KC.
- Substance restrictionsRoHS list (10 substances), REACH SVHC (~240 substances, twice-yearly updates), Prop 65 (~900 chemicals).
- Label requirementsCE mark, FCC ID, country of origin, importer details (EU 2025), batch ID, WEEE bin, battery icon.
- Test planPre-compliance during prototyping vs. only at the end. Pre-compliance is 5–10× cheaper.
3.Risk questions
Risks are the questions whose answers determine whether the project ships. Capture them explicitly so the team can address them in priority order.
3.1What the first prototype must prove
- Most uncertain technical questionMechanical fit, sensor accuracy, wireless range, thermal behaviour, antenna performance. Pick one.
- Most uncertain user-facing questionForm factor, interaction, runtime, audible/visual feedback.
3.2What could block the project
- Single-source componentsAnything that cannot be dual-sourced is a schedule risk.
- Tooling-heavy partsDecisions that cannot be changed cheaply after pilot production.
- CertificationStandards that could force a re-spin of mechanics, electronics, or firmware.
- IPPatents or trademarks held by competitors. Run FTO before tooling.
3.3What must be documented before tooling
- Mechanical critical dimensions and tolerances.
- Stable electronics architecture and schematic.
- BoM with at least two viable suppliers per critical line item.
- Pre-compliance plan and a known certification body.
- Approved cosmetic standards (golden colour chips, surface finish samples).
4.Specification sheet
The specification sheet is the file every supplier quotes against. The companion XLSX template implements the structure below as fillable fields.
4.1Header block
| Field | Example |
|---|---|
| Product name | Soil Moisture Sensor (Garden) |
| Model / SKU | IDB-SMS-G-001 |
| Revision | v1.0 |
| Date issued | 2026-05-28 |
| Owner | One person (not a committee) |
| Target markets | US / EU / UK |
| Effective date | 2026-06-15 |
| Supersedes | v0.9 (2026-04-12) |
| Status | Pre-RFQ / Quoting / Sampling / Production |
4.2Mechanical specification (template)
`` Overall dimensions: 120 × 80 × 18 mm (L × W × H) Tolerance: ±0.3 mm general (ISO 2768-m) ±0.05 mm critical mating surfaces (ISO 2768-f) Weight target: 75 ± 5 g Enclosure material: PC + ABS 10% glass-filled, UV-stable Surface finish: SPI A2 (matte) Colour: Pantone 287 C (deep blue) Coatings: UV-cured pad print, logo white Sealing: IP65, silicone O-ring + ultrasonic weld Mounting: M3 inserts × 2, threaded brass Service access: Battery hatch with captive screw Drop spec: 1.2 m onto concrete, 6 faces ``
4.3Electronic specification (template)
`` Power source: Li-Po 3.7 V 1200 mAh (UN 38.3 cert) Voltage rails: 5 V (USB) / 3.3 V (MCU) / 1.8 V (sensor) Sleep current: <10 µA (firmware-verified) Active current: 45 mA typical, 80 mA peak (Tx) Battery life: 12 months @ 1 reading/hour Wireless: BLE 5.2, Nordic nRF52840 (pre-cert) Antenna: PCB trace, 2.4 GHz, +1 dBi Sensors: Capacitive moisture sensor, ±2 % FSR Soil temp NTC, ±0.5 °C 0–40 °C Connectors: USB-C (4-pin, no data) Firmware: v1.0, OTA via BLE, manufacturing test mode ``
4.4Bill of materials (per line, ref companion XLSX)
- Every line itemPart number, manufacturer, qty, target cost.
- Sourcing flagFactory-sourced (default) or customer-supplied (CKD).
- Critical-component flagSingle-source or long-lead items.
- AlternatesWhere dual-sourcing is acceptable, list second-source MPN.
- Revision trackingComponent-level revisions when needed.
4.5Packaging specification (template)
`` Primary packaging: Color box, 130 × 90 × 30 mm Matte litho print, 350 gsm SBS Magnetic-close flap, foam tray insert Inner packaging: Recyclable molded pulp tray Master carton: 48 units/carton, 540 × 320 × 200 mm Double-wall corrugated, BC flute Pallet config: 24 cartons/pallet (3 × 8) Pallet 1200 × 800 mm (Euro pallet) Pallet weight: ~85 kg ISPM 15 stamp: Required (HT-treated wood) ``
4.6Standards + labels (template)
`` Standards applied: US: FCC Part 15B/15C, CPSIA, Prop 65, FDA (food-safe) EU: LVD 2014/35/EU, EMC 2014/30/EU, RED 2014/53/EU RoHS, REACH, Battery Regulation UK: UKCA equivalent to above Substance: RoHS 2.0 compliant, REACH SVHC <0.1%w Required labels: CE, FCC ID, UKCA, country of origin Importer details (EU 2025) WEEE bin, battery icon Tracking label: Mfr, location, date code, batch ID Format: YYWW-XXXX (year-week-sequence) ``
4.7Files attached
4.8Sign-off block
- Both parties sign the same revision of the spec sheet.
- Authorised signatoryOne name per party. Title, email, phone.
- Effective dateWhen supplier commits to building to this revision.
- Supersede processSpec is invalid for revisions beyond listed version unless re-signed.