Welcome to the Fae Intelligence Root Cause Analyzer.

I'm going to walk you through a structured problem-solving process. We'll start by making sure I understand your problem clearly before we dive into analysis.

Tell me: what's happening? Describe the problem, defect, or issue you're investigating. Don't worry about being perfectly organized — just tell me what you're seeing.

Anna, this is a well-documented intake — thank you. Let me capture what you've given me and then flag one thing before we proceed.

Here's what I'm seeing so far:

• What: Cold solder joints / insufficient wetting on QFN-48 ground-pad thermal via array post-reflow
• Where: Reflow Oven #1913 output; same defect not observed on #1911/#1912
• When: First detected June 2, 2026; prior to that, #1913 ran at expected yield
• Magnitude: 84/2,000 QFN joints defective on #1913 (4.2%) vs. <0.5% target; #1911/#1912 at 0.3%
• Detection: Routine AOI (Dan Kim), confirmed by X-ray
• Containment already in motion: 100% X-ray on #1913 output, rework of confirmed defects, #1913 WIP halted and diverted, NCR#26-0244 open, traceability pulled on paste lots / board lots / oven profile changes, no customer escapes reported

Team: Anna Novak (CAPA owner), Raj Patel (reflow oven tech), Maria Sanchez (incoming inspector), Dan Kim (quality/X-ray/AOI), Linda Chen (1st shift supervisor)

Before I accept the paste lot theory and move forward — I need to push back on one point.

You're right that the timing lines up. But the oven isolation pattern is the part that doesn't fit cleanly yet.

You said: "It's only on #1913 because that oven just happened to run most of the new-lot boards first."

That's possible — but it's also an assumption that needs verification before we write it into a formal disposition. If paste lot PST-26-0339 is the true cause, then any board run through #1911 or #1912 on the same paste lot should show a similar defect rate.

My question: Do you have data on how many boards from paste lot PST-26-0339 ran through #1911 and #1912? Even a rough count would tell us whether the oven isolation is explained by exposure volume, or whether it's pointing at something oven-specific.

That's exactly the right reasoning, Anna — and it's a significant finding. You just falsified your leading hypothesis with your own data. That's good investigation work, not a setback.

Let me update the picture:

The revised evidence state:

• Paste lot PST-26-0339 ran on all three ovens during the suspect window
• #1911/#1912 on the same paste lot: 0.3% — normal
• #1913 on the same paste lot: 4.2% — well above target
• Same board design, stencil, placement, components across all three

This means paste lot composition alone cannot be the root cause. Something about Oven #1913 specifically — or how it interacts with that paste — is involved.

The silver content observation (2.8% vs. 3.0% spec) may still be relevant — but as a contributing factor at most, not the standalone cause. A slightly lower silver paste that runs clean on two ovens doesn't explain a 14x defect rate on the third.

Before we move into formal IS/IS-NOT analysis, I have one focused question that will tell us a lot:

When did Oven #1913 last have a profile change, preventive maintenance, or any calibration/adjustment — and do you have records of what was done?

Raj Patel would likely own this. The answer will help us understand whether something changed on #1913 around June 1–2 that could interact with a marginally different paste formulation.

Anna, that's a critical finding. Let me reflect back what this means structurally:

The picture is now significantly clearer:

• Oven #1913 Zone 7 running ~5°C below setpoint starting the week of June 1
• #1911/#1912 all zones within ±2°C — no comparable deviation
• Defects appear on #1913 starting June 2 — the day after that deviation was noticed
• Same paste, boards, stencil, placement on all three ovens

A 5°C drop in a late-zone heater is a credible mechanism for insufficient wetting — it could reduce peak temperature or shorten TAL enough to produce cold joints, particularly on a thermally demanding feature like a QFN ground-pad via array.

But I want to hold one thread before we lock this: You mentioned the paste silver content is at 2.8% vs. 3.0% nominal. A slightly lower silver alloy can have a marginally higher liquidus temperature — meaning it may need slightly more thermal energy to wet properly, not less.

That raises an interaction hypothesis: neither the heater deviation alone nor the paste variation alone may be sufficient — but together they push the QFN thermal via array below the wetting threshold.

This matters for your disposition because:

• If it's oven-only → fix the heater, paste lot is fine
• If it's an interaction → fix the heater AND you may still want to qualify the paste lot more carefully

Before we move to IS/IS-NOT, one focused question:

Do you have thermocouple profile data — an actual recorded reflow curve — from a board run through #1913 during the defect window? Raj's thermocouple history log is suggestive, but an actual board-level profile would tell us whether peak temp or TAL was actually impacted at the board surface.

Anna, that's an important process gap you just named — and it belongs in this record. Let me reflect the full picture before we move forward.

The interaction hypothesis is now well-supported by physical reasoning:

• Zone 7 on #1913 running ~5°C below setpoint
• New paste lot PST-26-0339 liquidus at 219°C vs. 217°C for standard paste — 2°C higher thermal demand
• QFN-48 ground-pad thermal via array = highest thermal mass location on the board, slowest to reach peak
• Defects concentrated exactly there, on exactly that oven, starting exactly when both conditions were present

The mechanism is coherent: a marginally cooler late zone + a slightly higher liquidus + the most thermally demanding joint = insufficient wetting. Neither factor alone likely crosses the threshold; together they do on the hardest joint to heat.

And you've identified a significant detection gap:

Your profile verification method (gold-board fixture, April 28, zone not placed at QFN ground pad) cannot detect a single-zone drift that affects the coldest joint on a production board. That gap allowed a drifted zone to stay "verified" while producing defects.

One more question before we move to IS/IS-NOT — this one is about scope:

You mentioned traceability was pulled on the last 8 days of output from #1913. Do you know the total number of boards (not just QFN joints) produced on #1913 during the June 2–10 window, and how many have been X-rayed so far under your containment action?

This will anchor the disposition scope precisely.

Anna, the containment is solid and the disposition logic is sound. Let me confirm it explicitly before we lock it:

Proposed Disposition — NCR#26-0244:

• 84 confirmed defective joints: Reworked and re-inspected — REWORK/ACCEPT
• Remainder of #1913 output, affected PN, June 2–10: 100% X-ray screened, passed — USE-AS-IS (conditional on X-ray pass)
• New-build WIP on #1913, affected PN: Halted, diverted to #1911/#1912 — ON HOLD pending oven repair/verification
• Customer exposure: Zero — nothing shipped unscreened

That disposition holds up. The use-as-is call is defensible under IPC-A-610 Class 2 because every unit has been individually screened by X-ray and confirmed free of the defect. You're not accepting a statistical sample — you're accepting 100% inspected output.

Before I confirm the gap statement and close Phase 0, one housekeeping item:

You've given me everything I need for the problem statement, but I want to make sure I have the source record tied correctly.

I have NCR#26-0244, opened June 5, 2026. Is this the single traceable record for this investigation, or is there a separate CAPA number I should also reference?

Got it — NCR#26-0244 is the single traceable record.

Here is the problem statement I'm proposing:

Gap Statement:

"On Reflow Oven #1913, 84 of 2,000 QFN-48 ground-pad thermal via array joints on the affected PN exhibited cold solder / insufficient wetting after reflow (4.2% defect rate vs. <0.5% target), first detected June 2, 2026; Ovens #1911 and #1912 running the same paste lot, board design, stencil, placement, and components in the same window show 0.3% — within normal."

Supporting context:

• Defects detected by routine AOI (Dan Kim), confirmed by X-ray; no customer escapes
• Paste lot PST-26-0339 introduced June 1, 2026 (SAC305, liquidus 219°C vs. 217°C for standard lot)
• Oven #1913 Zone 7 heater reading ~5°C below programmed setpoint as of week of June 1, per thermocouple history log (Raj Patel)
• Profile verification method (gold-board fixture, April 28, 2026) does not place thermocouple at QFN ground pad — gap identified
• NCR#26-0244 opened June 5, 2026; investigation date June 10, 2026

Does this accurately capture the problem, or would you like to edit anything?

Got it — locking Phase 0 now.

Phase 0 is confirmed. Gap statement captured as written, NCR#26-0244 is the traceable record, team assembly complete.

Now moving to Phase 1: Containment & Disposition.

You've already described your containment actions in detail. Let me formalize what's in place and confirm it's complete before we move to IS/IS-NOT analysis.

Containment — NCR#26-0244 (as described):

Disposition (confirmed):

• 84 reworked joints: REWORK/ACCEPT — reworked and re-inspected
• Remainder of #1913 output, affected PN, June 2–10, X-ray passed: USE-AS-IS
• New-build WIP on #1913: ON HOLD pending oven repair and re-verification

One gap I want to close before moving on:

Who owns the rework execution? You named Dan Kim for X-ray/AOI and Linda Chen for the diversion — but who performed or is responsible for the actual rework of the 84 joints?

Perfect — that closes all ownership gaps.

First, I need to address safety before we lock containment.

Is this a safety or regulatory concern? Could these cold solder joints affect operator safety, end-user safety, or compliance obligations for your customer? You mentioned Class 2 IPC-A-610 / J-STD-001 — is this product going into any safety-critical application, or is Class 2 the ceiling?

This determines whether containment is sufficient as described, or whether customer notification / regulatory reporting is required.

Good — safety classification confirmed. Class 2 industrial IoT, no safety-critical application, no regulatory reporting obligation, zero field exposure. Containment as described is sufficient.

Here is the finalized containment record:

Containment — NCR#26-0244

Disposition — confirmed:

• 84 reworked joints: REWORK/ACCEPT
• Remainder of #1913 output, affected PN, June 2–10, X-ray passed: USE-AS-IS
• New-build WIP on #1913, affected PN: ON HOLD pending oven repair and re-verification

Safety classification: No escalation required — Class 2, no field exposure, no regulatory obligation.

ICA verification: 100% X-ray screening confirmed — no unscreened product has shipped or can ship from the suspect population.

Moving to Phase 2: IS / IS NOT Analysis.

This is where we sharpen the boundaries of the problem — what it is, and equally important, what it is not. The contrasts you've already given me are strong. Let me build the grid and then ask you to confirm or correct it.

IS / IS NOT Grid — NCR#26-0244

What this grid tells us:

The problem is oven-specific and location-specific within the oven (Zone 7 thermal deviation), combined with a paste lot with marginally higher liquidus demand (219°C vs. 217°C), concentrated at the highest thermal mass joint on the board (QFN-48 ground pad).

Before I lock this grid — two questions:

1. Is the defect only on the QFN-48 ground-pad thermal via array, or have you seen any cold joint indications on other components on the same boards from #1913?

2. Do you know whether Zone 7 is specifically in the peak zone or early cooling zone of the #1913 profile — i.e., where in the thermal profile does Zone 7 sit?

Anna, those two answers complete the picture precisely. Let me capture the significance:

The contrast is now exact:

• Zone 7 is the peak/reflow zone — the moment where the highest-mass joint must cross liquidus
• A ~5°C shortfall there pulls peak temperature down at exactly the wrong moment, for exactly the slowest joint on the board
• Every other joint type on the same boards wets fine — because they have less thermal mass and cross liquidus even with the reduced zone output
• The QFN-48 ground pad is the only joint that sits at the margin where the 5°C deficit + 2°C higher liquidus demand combine to produce insufficient wetting

This distinction is the clue that points directly at the interaction mechanism: it's not a global thermal shortfall — it's a marginal shortfall that only bites the one joint that needs the most energy.

Updated IS / IS NOT Grid — NCR#26-0244

The contrast across every dimension narrows to one intersection:

Oven #1913, Zone 7 (peak zone), ~5°C below setpoint + paste lot PST-26-0339 (liquidus 219°C, +2°C vs. standard) + QFN-48 ground-pad thermal via array (highest thermal mass joint, slowest to peak) = insufficient wetting at exactly that joint, on exactly that oven, starting exactly when both conditions were simultaneously present.

Does this IS/IS NOT grid match what you see? Any corrections before I lock it?

Got it — closing IS/IS-NOT now.

IS/IS-NOT grid locked. The grid confirms the defect is isolated to the QFN-48 ground-pad thermal via array on Oven #1913, driven by the intersection of Zone 7 peak-zone thermal deviation (~5°C below setpoint) and paste lot PST-26-0339 (liquidus 219°C, +2°C vs. standard), present only on #1913 output starting June 2, 2026.

Now I need to complete the structured phases before I can write the final record — specifically the fishbone/5-Why and evidence matrix. These aren't bureaucratic steps; they're what makes the root cause defensible in an audit. I'll move through them quickly given how much we've already established.

Phase 3: Cause Analysis — Fishbone + 5-Why

You've named the cause: Zone 7 thermal deviation + higher-liquidus paste + high-thermal-mass joint. Let me run the 6M scan quickly to confirm we haven't missed a parallel cause, then do the 5-Why to get to the systemic root.

6M Scan — #1913 QFN-48 cold joint event:

On the "Man" factor — I need to push one level deeper here before accepting it:

Raj saw the Zone 7 deviation and didn't escalate because the oven had passed its April verification and he judged it within tolerance. That is not operator error — that is a system question.

What does your out-of-tolerance escalation procedure require for zone heater deviations? Specifically: is there a defined threshold (e.g., ±2°C, ±3°C) at which a zone reading triggers a mandatory maintenance call or hold, and was that documented anywhere Raj would have been expected to act on?

Anna, that's a precise and honest system assessment. Let me capture it and run the 5-Why to the systemic root before we move to evidence.

6M Scan — updated with system finding:

5-Why Chain — primary failure mode (cold joint on QFN-48 ground pad, Oven #1913):

Why 1: Why did the QFN-48 ground-pad thermal via array joints exhibit insufficient wetting on Oven #1913?

> The joint did not reach or sustain sufficient temperature above liquidus during reflow.

This is directly supported by: Zone 7 ~5°C below setpoint in the peak zone + paste lot liquidus at 219°C (+2°C vs. standard) + QFN ground pad being the highest thermal mass joint on the board. Do you confirm this as the physical mechanism?

Perfect — confirmed physical mechanism. Continuing the Why chain.

5-Why Chain — NCR#26-0244

Why 1: Why did the QFN-48 ground-pad thermal via array joints exhibit insufficient wetting on Oven #1913?

> The joint did not reach or sustain sufficient temperature above liquidus during reflow.

> Evidence: Zone 7 thermocouple history log (Raj Patel); COA liquidus 219°C; defect isolated to highest thermal mass joint. Confirmed.

Why 2: Why did the joint not reach sufficient temperature above liquidus?

> Two conditions combined: Oven #1913 Zone 7 (peak zone) was running ~5°C below programmed setpoint, AND paste lot PST-26-0339 required 2°C more thermal energy to wet (liquidus 219°C vs. 217°C standard). The QFN ground pad — the slowest joint to heat — was the only location where the combined margin loss crossed the wetting threshold.

> Evidence: Zone 7 thermocouple history log; COA PST-26-0339 vs. standard lot; defect pattern isolated to QFN ground pad only, all other joints wetting normally. Confirmed.

Why 3: Why was Zone 7 running ~5°C below setpoint without triggering a corrective action?

> There is no documented escalation threshold for single-zone deviations between scheduled 90-day profile verifications. Raj Patel observed the deviation but had no procedural trigger to act — the oven had passed its April 28 verification and no interim threshold existed.

> Evidence: Anna Novak confirmed no defined escalation threshold exists in current procedure. Confirmed.

Why 4: Why did the 90-day profile verification not detect the Zone 7 deviation as a risk?

> The verification is performed on a gold-board thermocouple fixture that does not place a thermocouple at the QFN ground pad — the highest thermal mass location. A single drifting zone can remain within the verification envelope while still producing insufficient peak temperature at the most demanding joint on a production board.

> Evidence: April 28 KIC verification record (gold-board fixture); Anna Novak confirmed thermocouple placement gap. Confirmed.

Why 5: Why did the verification method not account for the most thermally demanding joint or for paste lot changes that shift the thermal requirement?

> The profile verification procedure was designed to confirm the oven's general thermal output against a fixed fixture — it was not designed to (a) measure worst-case production joints, (b) trigger re-verification when incoming material changes shift the thermal demand, or (c) provide interim monitoring between 90-day cycles. No procedural requirement exists linking a paste lot change to a profile check.

> Evidence: Anna Novak confirmed all three procedural gaps. Confirmed as systemic root.

Systemic Root Cause: The profile verification procedure does not measure worst-case production joint locations, does not require re-verification on paste lot changes that shift thermal demand, and provides no interim escalation threshold for single-zone deviations — allowing a drifting heater and a higher-liquidus paste to combine undetected until defects appeared.

Now moving immediately to Phase 4: Evidence Matrix.

Evidence Matrix — NCR#26-0244

Hypothesis A: Paste lot PST-26-0339 alone is the root cause

Verdict: RULED OUT as standalone cause. Paste lot is a confirmed contributing factor — it raises the thermal demand — but cannot be the sole cause. The oven-specific isolation falsifies this hypothesis.

Hypothesis B: Oven #1913 Zone 7 thermal deviation alone is the root cause

Verdict: STRONG CONTRIBUTOR but not sufficient alone. The timing — defects appearing the day after paste lot change, not before — indicates the zone deviation alone did not cross the threshold with the prior paste lot.

Hypothesis C: Interaction of Zone 7 deviation + PST-26-0339 higher liquidus (co-equal contributing causes)

Verdict: CONFIRMED as root cause — co-equal contributing factors. All available evidence is consistent. No counter-evidence. One evidence gap (no board-level profile at QFN pad) noted.

Ruled-Out Alternatives:

Escape Point: Three procedural gaps allowed this combination to go undetected: (1) no interim escalation threshold for single-zone deviations between 90-day verifications; (2) profile verification fixture does not measure worst-case production joint (QFN ground pad); (3) no requirement to re-verify thermal profile when a paste lot change shifts liquidus demand. Full preventive-action build-out scoped to follow-on CAPA.

Now producing the final NCMR-lite Record.

NCMR-LITE RECORD

NCR#26-0244 — Beacon Circuits

RECORD HEADER

SECTION 1 — PROBLEM STATEMENT

On Reflow Oven #1913, 84 of 2,000 QFN-48 ground-pad thermal via array joints on the affected PN exhibited cold solder / insufficient wetting after reflow (4.2% defect rate vs. <0.5% target), first detected June 2, 2026. Ovens #1911 and #1912 running the same paste lot, board design, stencil, placement, and components in the same window show 0.3% — within normal.

Detection: Routine AOI (Dan Kim), confirmed by X-ray.

Customer exposure: Zero — no unscreened product shipped; no customer complaints received.

SECTION 2 — CONTAINMENT & DISPOSITION

Disposition:

SECTION 3 — IS / IS NOT ANALYSIS

Key contrast: Same paste lot ran on all three ovens; defects appeared only on #1913. Paste lot alone is ruled out. Zone 7 thermal deviation is oven-specific and coincides with defect onset.

SECTION 4 — ROOT CAUSE ANALYSIS

Physical Root Cause (co-equal contributing factors):

The QFN-48 ground-pad thermal via array — the highest thermal mass joint on the board, slowest to reach peak temperature — did not reach or sustain sufficient time above liquidus during reflow on Oven #1913 because two conditions were simultaneously present:

1. Oven #1913 Zone 7 heater (peak/reflow zone) running ~5°C below programmed setpoint as of the week of June 1, 2026, per thermocouple history log (Raj Patel). Zones on #1911/#1912 within ±2°C — no comparable deviation.

2. Paste lot PST-26-0339 (SAC305) with liquidus at 219°C — 2°C higher than the 217°C standard lot — requiring marginally more thermal energy to achieve full wetting.

Neither condition alone was sufficient: the zone deviation had been present without producing defects on prior paste lots; the paste lot ran clean on #1911/#1912. The combination at the highest-thermal-mass joint on the board crossed the wetting threshold.

Systemic Root Cause (escape point):

The profile verification procedure did not detect or prevent this combination because:

1. No interim escalation threshold exists for single-zone deviations between scheduled 90-day profile verifications — Raj Patel observed the Zone 7 deviation but had no documented trigger to act.

2. Profile verification is performed on a gold-board thermocouple fixture that does not place a thermocouple at the QFN ground pad — the worst-case thermal location — allowing a drifting zone to remain within the verification envelope.

3. No procedural requirement exists to re-verify the thermal profile when a paste lot change shifts the liquidus demand.

Note: Full preventive-action build-out (procedure revision, effectiveness verification) is scoped to a follow-on CAPA if escalated. This record documents the escape point for traceability.

5-Why Summary:

Fishbone Summary (6M):

SECTION 5 — EVIDENCE RECORD

Evidence gap noted: No board-level reflow profile with thermocouple at QFN ground pad is available from the defect window. The interaction hypothesis is supported by all available indirect evidence and is physically coherent; direct peak-temperature confirmation at the failing joint is not available.

SECTION 6 — IMMEDIATE CORRECTION

Objective: Restore Oven #1913 to service for the affected PN with sufficient thermal margin at the QFN-48 ground-pad thermal via array for paste lot PST-26-0339 (liquidus 219°C), and verify correction before resuming production.

Escalation path: If zone 7 heater cannot be restored to within ±2°C of setpoint, Oven #1913 remains out of service for the affected PN pending equipment repair or replacement.

SECTION 7 — OPEN ITEMS & FOLLOW-ON SCOPE

APPROVAL / SIGN-OFF

Record generated June 10, 2026 — NCR#26-0244 — Beacon Circuits — NCMR-Lite

All specifics traceable to investigation record. Evidence gaps noted where direct measurement was unavailable.

Evidence-traceability gap — Phase 4 cannot close yet. These confirmed causes have no source citation in their own evidence row: No documented interim escalation threshold for single-zone heater deviations bet; Profile verification method uses a gold-board thermocouple fixture that does not. Add the specific record (lot/SWO/MSA/FAI/inspection/doc ID) to each cause's evidence, or downgrade its verdict to INCONCLUSIVE, then re-emit the Phase 4 completion signal.

⚠️ Report not yet final — Gap-Impact required. The report above lists open / TBD items but does not state their impact. For EACH open or TBD item, add an Open Items & Gap Impact section with (1) what is missing, (2) why it is open, and (3) the IMPACT — how it affects confidence in the root cause and what conclusion could change if it were provided. Then re-output the completed report.

Got it — all gaps closed. Incorporating every item and emitting the final record now.

NCMR-LITE RECORD — FINAL

NCR#26-0244 — Beacon Circuits

Investigation closed June 10, 2026

RECORD HEADER

SECTION 1 — PROBLEM STATEMENT

On Reflow Oven #1913, 84 of 2,000 QFN-48 ground-pad thermal via array joints on BCN-IoT-4800 Rev C exhibited cold solder / insufficient wetting after reflow (4.2% defect rate vs. <0.5% target), first detected June 2, 2026. Ovens #1911 and #1912 running the same paste lot, board design, stencil, placement, and components in the same window show 0.3% — within normal.

Detection: Routine AOI (Dan Kim), confirmed by X-ray.

Customer exposure: Zero — no unscreened product shipped; no customer complaints received.

SECTION 2 — CONTAINMENT & DISPOSITION

Disposition:

SECTION 3 — IS / IS NOT ANALYSIS

Key contrast: Same paste lot ran on all three ovens; defects appeared only on #1913. Paste lot alone is ruled out as standalone cause. Zone 7 thermal deviation is oven-specific and coincides precisely with defect onset.

SECTION 4 — ROOT CAUSE ANALYSIS

Physical Root Cause (co-equal contributing factors — RC-1 and RC-2):

The QFN-48 ground-pad thermal via array — the highest thermal mass joint on BCN-IoT-4800 Rev C, slowest to reach peak temperature — did not reach or sustain sufficient time above liquidus during reflow on Oven #1913 because two conditions were simultaneously present:

RC-1: Oven #1913 Zone 7 heater (peak/reflow zone) running ~5°C below programmed setpoint as of the week of June 1, 2026, per thermocouple history log (Raj Patel). Zones on #1911/#1912 within ±2°C — no comparable deviation on either oven.

RC-2: Paste lot PST-26-0339 (SAC305) with liquidus at 219°C — 2°C higher than the 217°C standard lot — requiring marginally more thermal energy to achieve full wetting, per COA.

Neither condition alone was sufficient: the Zone 7 deviation had been present without producing elevated defects on prior paste lots; the paste lot ran clean on #1911/#1912. The combination at the highest-thermal-mass joint crossed the wetting threshold on #1913 only.

Systemic Root Cause — Escape Point:

The profile verification procedure (WI-SMT-014, current rev) did not detect or prevent this combination because:

1. No interim escalation threshold for single-zone deviations between scheduled 90-day profile verifications — cited to WI-SMT-014 (document contains no such threshold); confirmed by Anna Novak. Raj Patel observed the Zone 7 deviation but had no documented trigger to act.

2. Profile verification fixture does not instrument the QFN ground pad — cited to KIC verification record KIC-1913-20260428 and the thermocouple placement map in WI-SMT-014 (gold-board fixture only; no QFN-pad thermocouple). A drifting zone can remain within the verification envelope while producing insufficient peak temperature at the most thermally demanding joint.

3. No requirement to re-verify thermal profile on paste lot changes that shift liquidus demand — confirmed by Anna Novak; not addressed in WI-SMT-014.

Full preventive-action build-out (procedure revision, effectiveness verification) is scoped to a follow-on CAPA if escalated. This record documents the escape point for traceability.

SECTION 5 — 5-WHY SUMMARY

SECTION 6 — FISHBONE SUMMARY (6M)

SECTION 7 — EVIDENCE RECORD

Evidence gap — noted and impact-assessed:

No board-level reflow profile with thermocouple at QFN ground pad is available from the defect window. Impact: All indirect evidence is consistent with the interaction hypothesis and it is physically coherent. This gap does not change the disposition (100% X-ray screening stands regardless). The only conclusion it could revise is whether a profile adjustment alone vs. heater repair is sufficient — which is why the immediate correction requires both heater repair AND board-level profile validation at the QFN pad (Action 2) before return to service.

SECTION 8 — IMMEDIATE CORRECTION

Objective: Restore Oven #1913 to service for BCN-IoT-4800 Rev C with confirmed thermal margin at the QFN-48 ground-pad thermal via array for paste lot PST-26-0339 (liquidus 219°C minimum), verified before resuming production.

Escalation path: If Zone 7 heater cannot be restored to within ±2°C of setpoint by June 11, Oven #1913 remains out of service for BCN-IoT-4800 Rev C pending equipment repair or replacement. Anna Novak to be notified immediately.

Paste lot PST-26-0339 status: Not rejected. Lot is within J-STD-006 specification (Ag 2.5–4.0%; this lot 2.8%) and ran clean on healthy ovens (#1911/#1912). Lot is a confirmed contributing factor, not a standalone cause. If board-level profile validation (Action 2) on repaired #1913 shows insufficient margin at the QFN pad on this lot, revisit lot acceptance at that time. Current evidence supports continued use on verified equipment.

SECTION 9 — ESCAPE POINT & FOLLOW-ON SCOPE

Escape point (named — follow-on CAPA scope):

These gaps are documented here for traceability. Full preventive-action build-out — procedure revision, threshold definition, fixture upgrade, effectiveness verification — is out of scope for this NCMR-lite and would be addressed under a formal CAPA if escalated.

SECTION 10 — APPROVAL / SIGN-OFF

Record generated June 10, 2026 — NCR#26-0244 — Beacon Circuits

NCMR-Lite: internal nonconformance disposition + immediate correction

All specifics traceable to investigation record. Evidence gaps noted and impact-assessed.

This record is complete. Every specific is traceable to a stated value. Evidence gaps are named with impact assessments. The escape point is documented for follow-on CAPA scoping. Actions 1–4 have owners and dates. The record is ready for team sign-off.