03.09 Key Component Selection: Five-Dimension Decision

Governance metadata | Owner: Head of Supply Chain | Last reviewed: 2026-10-22 | Next review: 2027-01-31

Core principle: only 5~10 parts in a piece of hardware truly decide whether it lives or dies. Key components such as the main SoC, sensors, motors, batteries and optics, once chosen badly, turn every later effort into debt repayment — costs that will not come down, certifications that cannot be cleared, and products discontinued half a year after mass production. This document sets out the identification criteria for key components and the five-dimension decision model, turning component selection from "engineer preference" into a decision that can be reviewed. Cost reverse-engineering: see 02.08; dual-sourcing switchover: see 03.06; tooling validation: see 03.01.

1. Why Component Selection Deserves Its Own Document

Our existing supply-chain interfaces are split by responsibility, but one link is missing:

Document	What it covers	What it does not cover
03.01 Tooling Engineering	How to tool the structure and how to accept it	Which components go inside
03.02 Contract Manufacturing Control	Who manufactures for us, commercial terms and yield	Which parts to select
03.06 Dual Sourcing	How to cut single-point risk	Whether to select it in the first place
03.07 SQE	How incoming quality is managed	Why this part was chosen
03.09 (this document)	Which parts to select, and on what basis	How to manage them afterwards

Three kinds of debt you pay for choosing a key component wrong:

Cost	Symptom	Latest point of detection
Cost debt	High unit price / low integration / extra peripheral circuitry required	Visible as soon as mass production starts; no way back
Compliance debt	RF / energy efficiency / materials fail target-market certification	Only surfaces at the T-6M certification sample submission
Supply debt	Discontinuation, longer lead time, no substitute	Blows up 6~12 months after mass production

Of the three, supply debt is the most expensive: it hits after you have already loaded inventory and pushed product through the channel. That is exactly the origin of the "red single point" in 03.06, and the source must be stopped at the selection stage.

2. What Counts as a Key Component: Four Identification Criteria

Not every part number needs a five-dimension review. Screen with these four criteria; meeting any two of them makes a part a key component:

#	Criterion	Deciding question
1	Cost share	Does the part account for ≥ 5% of the BOM?
2	Performance-determining	Do its specifications directly determine the core selling point?
3	Compliance constraint	Does it involve mandatory certification for RF / energy efficiency / battery / materials?
4	Supply risk	Is the lead time > 8 weeks, or is the manufacturer's lifecycle < 5 years?

Typical key component list (by category):

Category	Common key components
Smart imaging	Main SoC, image sensor, optical lens group, storage
Cleaning robots	Main controller, LiDAR / vision module, motors, battery pack
Energy storage	Cells, BMS controller, inverter module, connectors
Wearables	Main controller, biosensors, battery, display
Audio	Main controller, Bluetooth module, amplifier, speaker units

3. The Five-Dimension Decision Model

Score every key component across five dimensions. The weights are not fixed — they depend on the category, but they must be stated explicitly.

Dimension	What is reviewed	Data source
Performance	Whether it meets the core specifications; whether the margin is sufficient (recommended ≥15%)	Specification sheet, measured samples
Cost	Unit price + peripheral circuitry + processing difficulty + yield loss, i.e. the total cost	02.08 Teardown, distributor quotes
Supply	Lead time, MOQ, manufacturer longevity commitment, capacity elasticity	Manufacturer / distributor, 03.06
Compliance	Whether target-market certification has been passed; whether remediation is required	07.02 Wireless Market Access
Substitutability	Whether a pin-to-pin or firmware-level substitute exists; switching cycle	Manufacturer roadmap, substitute-part qualification

Scoring Criteria (Example; Adjust Weights by Category)

Dimension	1 point	3 points	5 points
Performance	Barely meets spec	Meets spec with 15% margin	Meets spec with 30%+ margin
Cost	Highest total cost	Median	Lowest total cost with high yield
Supply	Single source, lead time >16 weeks	Dual source, lead time 8~16 weeks	Multiple sources, lead time <8 weeks
Compliance	Not certified, remediation required	Certification in progress	Target-market certification passed
Substitutability	No substitute	Substitute exists but needs board changes	pin-to-pin, drop-in replacement

Discipline: scoring exists to surface disagreement, not to compute a single right answer. If any dimension scores 1 point, you must write down "the reason for accepting the risk + the closure plan + the owner"; otherwise the part may not enter 01.08 GR2.

4. Component Selection Decision Matrix (Template)

⚠️ The value columns must be filled in from measurements; scores must be jointly confirmed by the review board and never entered by a single person.

Candidate	Part number	Weighted score
A
B
C
Weight	—	100%

Decision record (mandatory fields):

Item	Content
Selected option
Rejected options and reasons
Residual risk accepted
Risk closure plan and owner
Re-review trigger conditions	(Price increase / longer lead time / discontinuation notice / certification failure)

5. Hard Disqualifiers (Non-Negotiable)

If a candidate meets any one of the following, it is eliminated outright; no management exception is accepted:

[ ] The manufacturer's longevity commitment is < 5 years (or it is in EOL/NRND status)
[ ] The key component is single-sourced with no substitution path (red-line single point, see 03.06)
[ ] Target-market mandatory certification has not been passed and there is no clear remediation path
[ ] Lead time > 16 weeks with no backup capacity
[ ] The part involves controlled items and export-control screening has not been completed (see 07.12)

This sits alongside the double-blind circuit breaker in 01.07 GR1 — "BOM ≤ 30% MSRP + PCB area ≤ 85% stacking limit". Those two rules govern the total, while this one governs the individual part.

6. Interfaces with Adjacent Documents

02.08 Teardown reverse engineering → Learn which parts competitors use and at what cost
        ↓
03.09 Component selection (this document) → Decide which parts we use
        ↓
03.01 Tooling / DFM → Whether the structure fits them and whether they are buildable
03.02 Contract manufacturing → Who builds it and at what yield
03.06 Dual sourcing → Where the second source for that part is
07.02 Certification → Whether that part can pass certification
        ↓
01.08 GR2 tooling and lock-order → Selection conclusions enter the risk list

Interface rules:

Rule	Explanation
Teardown before selection	Without benchmarking from 02.08, selection is nothing but engineer preference
Selection before tooling	Freezing key component specifications is a precondition for the T0 trial mold in 03.01
Dual sourcing follows selection	The second source must be defined at the same time as the key component is selected, see 03.06
Certification follows selection	For parts with compliance constraints, the certification schedule starts during selection, see 07.02

7. Common Mistakes

Mistake	Consequence	Correction
Judging unit price only, ignoring total cost	Peripheral circuitry and yield losses eat back the savings	Use the total-cost basis
Judging performance only, ignoring lifecycle	Discontinued half a year after mass production, forcing a board redesign	Request the manufacturer longevity commitment letter
Picking niche parts for differentiation	Long lead time, no substitute, poor ecosystem	Prefer mainstream parts for key components
One-person decision	Nobody reviews the risk	Review board + decision record
Ignoring compliance constraints	T-6M certification failure, launch delay	Start certification during the selection stage
Thinking about the second source only after selection is done	The switching cycle cannot be met	Define dual sourcing together with selection

Execution Checklist

[ ] Key component list identified: screened with the four criteria, meeting any two of them
[ ] Five-dimension weights stated by category: performance / cost / supply / compliance / substitutability
[ ] Total-cost basis applied: includes peripheral circuitry, processing difficulty and yield loss
[ ] Longevity commitment obtained: stamped document from the manufacturer or a tier-1 distributor
[ ] Compliance constraints confirmed: target-market certification status and remediation path
[ ] Substitution path defined: pin-to-pin or firmware-level, with the switching cycle estimated
[ ] Hard disqualifiers checked one by one: all 5 passed
[ ] Decision record completed: rejection reasons, residual risk, closure plan, owner
[ ] Re-review trigger conditions set: price increase / lead time / discontinuation / certification failure
[ ] Conclusions entered in the GR2 risk list: see 01.08

03.09 Key Component Selection: Five-Dimension Decision ​

1. Why Component Selection Deserves Its Own Document ​

2. What Counts as a Key Component: Four Identification Criteria ​

3. The Five-Dimension Decision Model ​

Scoring Criteria (Example; Adjust Weights by Category) ​

4. Component Selection Decision Matrix (Template) ​

5. Hard Disqualifiers (Non-Negotiable) ​

6. Interfaces with Adjacent Documents ​

7. Common Mistakes ​

Execution Checklist ​

Related Documents ​