Inspect the Completed Assembly

# Inspect the Completed Assembly: A Risk Between Leads, Not Within the Device

Every placement concern this process has addressed so far — the junction-bearing section, the base wire, the contacted element — was about getting one lead to the right place inside the device. This inspection checks something categorically different: whether the three leads, now all attached and routed out of the same small assembly, stay far enough apart from each other to avoid becoming an electrical path of their own. Two correctly-placed leads that happen to run too close together create a risk the rest of this process never had to consider — not a wrong connection inside the transistor, but an unwanted connection between its external terminals, through nothing more than inadequate clearance.

## 1. Lead Separation Has to Hold Off the Device's Own Operating Voltage

$$V_{\text{breakdown}} \approx E_{\text{air}} \cdot d_{\text{separation}}$$

The air gap between any two leads can sustain a voltage roughly proportional to its own length, scaled by air's dielectric strength $E_{\text{air}}$ — which means lead separation isn't just a mechanical tidiness concern, it's a direct electrical safety margin against the voltages the finished device will actually see in operation. A separation adequate for simple continuity testing on a bench can still be inadequate once the device is biased at its full rated collector voltage, the same voltage already driving step nineteen's reach-through concern at the junction itself, now posing an analogous risk externally between the leads rather than internally across a depletion region.

## 2. Real Diagram: Checking Clearance, Not Just Connection

Terminal Separation — a Risk Between Leads, Not Inside the Bar each lead individually correct doesn't guarantee they're safely apart from each other adequate clearance emitter base collector d > required margin inadequate clearance emitter base collector d too small the right-hand pair can arc or leak under the device's own rated voltage

## 3. This Is the Last Step Where Lead Position Can Still Be Corrected

$$t_{\text{inspection (step 33)}} < t_{\text{encapsulation (step 34)}}$$

Once the can seals in the step immediately following this one, the physical geometry of all three leads is locked in permanently, with no further opportunity to reposition anything found marginal here. This inspection sits at the same kind of deadline step twenty-eight's rinse and step thirty-two's gain check both faced — a last chance before an irreversible packaging step — but checks a different property entirely: not whether the device works electrically, but whether its finished geometry stays safe once it's sealed and biased for the rest of its service life.

Breakdown Voltage vs. Lead Separation V_breakdown ≈ E_air · d_separation — roughly linear for small air gaps lead separation, d → breakdown voltage device rated voltage minimum safe separation too close — fails under rated bias this line is the actual pass criterion this inspection checks against

## Inspect the Completed Assembly's Place in the Process Lineage

Inspecting the completed assembly is step thirty-three of the 1951 grown-junction transistor's full manufacturing sequence — the first step of protecting and qualifying the device, after the contacted element has been checked for transistor action, and before the transistor is enclosed. It is the step that checks inter-lead clearance rather than intra-device placement, the last opportunity to catch a terminal-separation problem before the can permanently locks the geometry in place.

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