A dimensioned technical drawing flat on a pale bench with a thin pen and folding dividers

Resources · four guides, no gate

Sourcing guides and engineering notes

Written from the trading-company position, by the people who carry the order. Usable whether or not you ever contact us.

No email gate Standards cited by revision Figures dated

01What this library is for

Four questions that arrive before a purchase order.

4 guidesReadable in one sitting

A clipboard holding a blank ruled form with a pen and a teal sticky tab, photographed from above — Fig. A These are the checklists we run on our own suppliers.

A row of finished modules in black and white enclosures standing on a pale surface — Fig. B Every claim carries a number, a code or a mechanism.

Rows of SMT placement machines and feeder banks receding down a bright assembly line — Fig. C The floor the guides are written about.

Guide 1 asks Who am I buying from? Six identity anchors and seven mismatch signals, tested before money moves.

Guide 2 asks What do I send? The file set and the acceptance class that turns three quotes into three comparable quotes.

Guide 3 asks What did my Incoterm buy? Risk transfer and clearance, rule by rule, including the C-group trap.

Guide 4 asks What should a visit achieve? Two days, the records to request on site, and how a hosted visit runs.

If a guide tells you to spend money with somebody else — an inspector, a test lab, your own broker — it still says so.

02The four guides

Start with the one that matches your situation.

Standards by revisionPrices published

A dimensioned engineering drawing sheet with a pencil and a pair of dividers laid over it

G-01

How to vet a Chinese electronics supplier

Start here if you have a quotation and no site visit.

Six anchorsSeven signalsCertificate look-up

AQL 0 / 2.5 / 4.0 · $20,000 order walk-through

A production panel of identical green circuit boards held in a white inspection fixture

G-02

The spec sheet: what to send us

The file set that makes quotes comparable.

Gerber / ODB++StackupTarget class

IPC-A-610J Table 1-1, five lifecycle stages

An open shipping container at a loading dock with unlabelled cartons stacked on a pallet inside

G-03

Incoterms 2020 for electronics buyers

Your quotation says CIF — what did you actually buy?

11 rulesICC (A) vs ICC (C)No EXW code

In force since 2020-01-01

A single visitor in a white coat walking the aisle of a bright assembly hall between rows of machines

G-04

Your first factory visit in Shenzhen

What two days can and cannot accomplish.

SMT questionsESDRecords on site

Audit ladder $220–458 per man-day

03Which guide you need, by situation

Five situations, one reading list.

The same methods apply to us

Technical drawings with digital calipers, a drafting triangle and machined sample parts on a pale bench — Fig. C A working prototype and a BOM: the spec-sheet guide.

A wide production floor from a raised viewpoint, three rows of identical assembly machinery between painted walkways — Fig. D Booking flights: the two-day visit plan.

Found on a platform The price looks good Vetting guide — the identity chain behind the price.

Working prototype And a BOM Spec-sheet guide — what makes three quotes comparable.

Quotation says EXW Or CIF, or DDP Incoterms guide — the risk-transfer table, rule by rule.

Booking flights Two days in Shenzhen Visit guide — the on-site document list and the debrief.

Checking us Rather than them Any of the four — the checklists have no version for us.

04Where the numbers come from

Sourced, dated, or labelled.

Vendor claims labelledForecasts labelled

Close macro of a circuit board edge showing stacked copper planes and plated holes — Standards Cited by revision and date: IPC-A-610J (March 2024), J-STD-001J, IPC-6012F.

Circuit boards and assembled modules laid out on a pale bench beside a monitor — Network 24 of 24 sites HTTP-verified reachable on 2026-09-13.

Certification A count over 24 sites 12 publish ISO 9001, 15 carry RoHS, 15 carry CE, 2 none. The trading company holds no citable certificate.

Worked examples Four Group C sites Saturn PCBA, Whale PCBA, Uppcba, Kingdta — one publishes in Simplified Chinese only.

Not published No electronics VAT rebate rate No rate appears on this site, because none could be verified.

Conflicting sources Said out loud Where two sources disagree, the guide names both rather than the friendlier figure.

How we verify a supplier

05Free tools on the roadmap

Planned. Not live.

Nothing on this list works today

Hands closing digital calipers around a machined part beside a clipboard with a blank inspection sheet

Planned — not live

AQL sampling calculator

Enter a lot size, read the sample size and the accept / reject numbers.

ISO 2859-1Level IICritical 0

Build first · a 2,000 lot returns 125 pieces

A production panel of identical printed circuit boards held in a white inspection fixture

Planned — not live

PCB capability comparison sheet

Layers, trace and space, thickness, drill, copper weight, finish.

1–58 layers0.1 mm trace0.15 mm drill

Build second · across the Group C board sites

Pallets of plain cartons staged in a large empty dispatch hall under ceiling lights

Planned — not live

Landed-cost and tariff estimator

Read a landed cost rather than a unit price, with each measure on its own line.

HS codeOriginStacked measures

Build last · third-party rate data moves

All three are roadmap items. No page on this site offers one as a working tool, and no result can be requested today. Roadmap order: AQL calculator, capability sheet, landed-cost estimator.

06Questions this library gets

About the guides themselves.

PSI $199–320Audit $220–458Social $350–500

An engineer's hands at a bench under an inspection lamp, working on a board with tweezers beside an open laptop — Fig. E The IPC set moves on a published timetable.

An empty industrial corridor with a closed roller door and a painted floor line running to the far end — Fig. F Audit prices are published so you can buy the inspection yourself.

China-specific? Mostly yes The customs, rebate and audit mechanics are Chinese; the standards and Incoterms are international.

Use them elsewhere? Yes, deliberately The checklists work on any supplier, including one who is not ours.

Kept current? On a timetable IPC-A-610K is scheduled for 2027-01 and IPC-6012G for 2027-03.

Do you publish a certificate? No The 24 sites publish their own; the trading company holds no citable certificate.

07Start

Use the guides, then send the spec.

The checklists are free and un-gated. The assessment is what an engineer writes back.

Recorded. An engineer will reply.

Written technical assessment, from eric@dfshk.cn.

Start with the vetting guide eric@dfshk.cn · +86 152 3512 7440