4.3 The Incoming Inspection Plan (IQC)

The receiving dock is the firewall of the factory. If defective material crosses this line, the cost of quality explodes by 10x (at board test) or 100x (in the field). The Incoming Quality Control (IQC) team is the operationalfinancial armfirewall of the SupplierEMS Qualityfactory. organization.Once a defective component is soldered onto a PCB, the cost of rejection increases by factor of 10 (rework) to 100 (scrap).

We do not inspect quality into the product; we verify that the supply chain has delivered the quality promised. This chapterplan defines the rules of engagementlogic for inspection,accepting materials into the sampling logic that governs lot acceptance, and the binary triggers for quarantine.warehouse.

TheRisk-Based Inspection Logic

Inspecting 100% of incoming resistors is an operational failure. Use a risk-based approach to allocate IQC Mandateresources where failure is most likely and most costly.

Class A: High Risk (RulesCritical Owned/ by SQE)

The IQC Inspector does not invent the rules; they execute the legislation written by the Supplier Quality Engineer (SQE).

Custom)

• Items: PCBs, Custom Mechanicals (Plastics, Metals), Cables, Displays, Batteries, Safety Critical Parts.
• Logic: These have high variability or severe impact on safety.
• Action: AQL 0.65 or 1.0 (Level II). Mandatory dimensional and visual checks.

Class B: Medium Risk (Active Components)

• Items: ICs, Connectors, LEDs, Transistors, expensive Modules.
• Logic: Manufacturing defects are rare, but handling/packaging errors (MSL, ESD) are common.
• Action: AQL 1.0 (Level I). Verify Labels, Packaging, and Lead Condition.

Class C: Low Risk (Standard Passives)

• Items: Resistors, Capacitors, Screws, Washers (Standard Catalogue parts).
• Logic: Production processes are automated and highly stable.
• Action: Dock-to-Stock (DTS). Verify Manufacturer P/N and Quantity only. No physical inspection unless flagged by production failures.

The InspectionGolden PlanRules of Verification

Before opening a reel or box, perform the "Label vs. System" triangular check. 90% of IQC escapes are administrative errors, not physical defects.

1. MPN Match:: EveryDoes the Manufacturer Part Number (PN) must have a defined Inspection Plan inon the ERP/QMSlabel system.
   • Standard: If no plan exists,match the defaultERP issystem "Identify & Count"exactly (Verification of MPN, Quantity, and Damage).
   • Critical: For Tier 1 parts, the SQE must define specific Critical to Quality (CTQ) dimensions? (e.g., "ATMEGA328P-AU ≠ ATMEGA328P-MU).
   • AVL Verification: Is this manufacturer on the Approved Vendor List for this specific project?
   • Date Code: Is the component within the allowable age window (typically < 2 years)?
     • If Date Code > 2 years -> Block and request Solderability Test.

Component-Specific Inspection Criteria

Apply these specific checks based on the component family.

A. Bare PCBs (The Foundation)

The PCB is the most complex component. If it fails, the PCBA is scrap.

• Warpage: Place on a surface plate. Bow and twist must be ≤ 0.75% of the diagonal dimension (unless IPC-6012 Class 3 requires tighter tolerance).
• Solder Mask: Check for peeling or blistering.
• Pads/Finish: Verify ENIG/HASL finish is not oxidized. Discoloration = Reject.
• Dimensional: Measure Pincritical Pitchcutouts and mounting holes against the drawing.

B. Moisture Sensitive Devices (MSDs)

ICs and modules packaged in moisture barrier bags (MBB) are time-bombs if mishandled.

• Humidity Indicator Card (HIC): Open the outer box. Check the HIC through the bag (if visible) or immediately upon opening.
  • If 10% spot is pink -> Reject or Bake immediately.
• Bag Integrity: Check for punctures or loss of vacuum. If the bag is not tight, the part is compromised.

C. Custom Mechanics (Enclosures / Metal)

• Fit Check: Perform a mating test with Caliper")a Golden Sample counterpart.
• Cosmetic: Inspect under standard lighting (800-1000 lux) at arm's length (40-50cm).
  • Scratches: None allowable on Class A surfaces (user-facing).
  • Flash/Burrs: Must not interfere with assembly or risk operator injury.
• DocumentationColor: Hygiene:Compare against the signed "Limit Sample" or Pantone swatch.

D. Connectors & Electro-Mechanical

• CoCPin Condition: Inspect for bent pins (Certificatecoplanarity). If pins are not flat, they will cause open circuits during reflow.
• Plating: Check for signs of Conformance):oxidation Mandatoryor forexposed everybase shipment.metal Muston statecontact adherence to the specific drawing revision.
• CoA (Certificate of Analysis): Required for raw materials (Solder Paste, Chemicals, Metal). Must show actual test data (e.g., Viscosity, Tensile Strength).
• Failure: Missing CoC/CoA = surfaces.Automatic Rejection. The lot cannot be received into stock.

Sampling and Acceptance CriteriaStrategy (AQL)

We do not guess; we use statistics. The Dannie Operating System utilizesUse ANSI/ASQ Z1.4 (equivalent to ISO 2859-1) standard for attribute sampling.

• SamplingNormal PlanInspection::
  • Normal: LevelStart II.here for all new vendors/parts.
  • Reduced Inspection:: LevelSwitch Ito this if the vendor passes 10 consecutive lots.
  • Tightened Inspection: Switch to this if 2 out of 5 consecutive lots are rejected.

  Scenario:

  You receive 500 units of a Custom Plastic Case (OnlyClass forA).

  "Dock-to-Stock"
  1. Look candidates)up Table: Lot size 281-500 -> Sample Size Code H.
  2. TightenedSample Size:: LevelInspect III50 (Forunits.
  3. AQL new1.0:
     • Accept: suppliers1 ordefect.
     • Reject: probation2 status).defects.
  4. AcceptanceAction: QualityIf Limityou find 2 bad units, reject the entire shipment. Do not sort them yourself unless explicitly authorized and charged back to the supplier.

  Non-Conformance Management (AQL):

  • CriticalMRB)

  Defect

  When (Safety/Functional):a lot fails inspection, it moves to the AQLMaterial 0.01.Review Board (0 defects allowed).

• Major Defect (Fit/Form/Function)MRB): AQLcage. 0.4.
• MinorIt Defectmust (Cosmetic):be AQLphysically 1.0.

The "Zero Defect" Goal (c=0):

• For high-reliability sectors (Auto/Med), we often adopt c=0 sampling, where any defectsegregated in the sampleERP rejectssystem the(Status: entire lot, regardless of AQL tables.BLOCKED).

Defect Classification

Inspectors must categorize findings to determine the severity of the rejection.Dispositions:

1. CriticalRTV (StopReturn Ship)to Vendor)::
    Standard procedure for defects.
   • DefinitionUAI (Use As Is):: HazardousRequires orEngineering rendersApproval. Used only if the unitdefect totallyis dead.
   • Example:cosmetic Wrong MPN, Mixed parts in reel, Cracked PCB, ESD bag puncture.
2. Major (Production Stopper):
   • Definition: Likely to cause failure or reduce usability.
   • Example: Bent pins, Oxidized leads (solderability), Wrong package size.
3. Minor (Process Indicator):
   • Definition: Deviation from standard butand does not affect function.form, fit, or function (e.g., wrong label font).
   • ExampleSort/Rework:: SlightEMS discoloration,performs Scratchedsorting/rework labelat the supplier's expense. Requires written agreement on hourly rates (readable).
   $) before work begins.

Switching

Pro-Tip: RulesIf (Dynamicyou Control)

accept

Thea rigor"marginal" of inspection adjusts automatically based on supplier performance history.

• Normallot to Tightened:
  • Trigger:keep 2the outline ofrunning, 5you consecutiveown lotsthe rejected.
  • Action:risk. MoveIf tothe Levelyield IIIdrops inspection.at SQESMT, notifiedthe immediately.
• Tightenedcustomer towill Normal:
  • Trigger:not 5pay consecutivefor lotsthe accepted.
  • Action:scrap. ReturnAlways toget Levela II.
• Normalconcession tonumber Reducedfrom (Dock-to-Stock):
  • Trigger:the 10customer/supplier consecutivebefore lotsusing acceptedmarginal + Approved Supplier Status (Grade A).
  • Action: Skip-Lot inspection (1 in 5).

parts.

Final Checklist

IQC ElementParameter	StandardSpecification	RiskAction of FailureOwner
MissingInspection Plan	Default to "ID & Count"Standard	CriticalANSI/ASQ defectsZ1.4, missedLevel II (Default).	IQC Lead
MissingCritical CoC	BlockMetric: ReceiptPCB	UntraceableBow/Twist material≤ 0.75%; Solderability pass.	IQC Inspector
Sampling	ANSI/ASQCritical Z1.4Metric: MSL	StatisticallyHIC invalidCard acceptancecheck mandated for all Bagged ICs.	IQC Inspector
Documentation	CoA (Certificate of Analysis) required for Chemicals/Plating.	Supplier
Rejection	Entire Lot (No Sorting)Trigger	"CherrryAQL picking"Threshold badReached lots-> Stop -> Notify Purchasing.	Quality Engineer
ESD/MSL	CheckDate BagCode IntegrityLimit	LatentMax field2 failuresyears from seal date (unless specified otherwise).	ERP System
Switching	Auto-TriggeredESD Control	InspectingIQC goodStation suppliersmust toobe muchgrounded; Wrist straps mandatory.	Safety Officer

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