Intermittent Ceramic Via Opens: Preserve Event Duration and Trigger Conditions

Measurement purpose

Establish the timing completeness and interpretation limits of intermittent continuity records on an identified ceramic via specimen.

Specimens and conditions

As-found connection

Restrain leads and record contact locations before any intervention that may remove the intermittent condition.

Stimulus history

Identify applied thermal or mechanical conditions and preserve measured rather than only commanded timing.

Equipment and records required

• Event acquisition: Provide qualified amplitude and duration sensitivity with known record length, trigger behavior and rearm gaps.
• Timing challenge: Use a safe independent interruption source or surrogate with traceable commanded events.

Method sequence

1. Qualify capture

   Challenge isolated, clustered and truncated interruptions through the final storage path.

   Record: Detection and timestamp comparison.

2. Observe specimen

   Acquire raw traces while logging blind periods and actual stimulus.

   Record: Coverage intervals and waveform files.

3. Classify events

   Separate complete events, incomplete durations and ambiguous gaps before interpreting location.

   Record: Event ledger with grouping rules.

Decision and uncertainty

A negative observation applies only to the stated detection boundary and covered time; incomplete records cannot establish absence of interruptions.

Include threshold noise, time-base alignment, trigger qualification and unobserved intervals in duration and recurrence interpretation.

The test owner defines the required event class; the acquisition engineer documents whether the saved record covers it.

Traceable outputs

Define the electrical event at a fixed test boundary

Name the via chain and its fixed terminals, excitation and voltage observation point. Define interruption amplitude, minimum relevant duration and recovery condition. A threshold crossing can represent an open, a partial resistance increase, a disturbed probe or source compliance behavior. The trigger identifies a candidate event; it does not establish a metallurgical cause.

Keep test leads restrained and record the specimen support and any thermal or mechanical stimulus. The present question is acquisition completeness on a stationary interconnect. Moving-contact mechanisms have additional kinematic and filtering requirements and should retain their separate validation plan. A static resistance pass cannot substitute for the event record when intermittent behavior is the concern.

Separate sample spacing from continuous observation

A high sample rate within one waveform says nothing about the interval before the next waveform. Distinguish sample spacing, record length, trigger holdoff, processing delay, rearming and file-transfer pauses. Review how the instrument behaves when memory fills or the host connection slows. These gaps can dominate a long unattended investigation.

For an illustrative acquisition that observes ten milliseconds then remains blind for ninety milliseconds, only ten percent of elapsed time is recorded. A high sample rate inside those ten milliseconds cannot establish that the other ninety were event-free. With randomly timed isolated short events and no correlation to the cycle, the coverage suggests a large miss opportunity; synchronized or clustered events invalidate a simple probability interpretation.

Specify trigger qualification and recovery behavior

Document trigger source, polarity, level, hysteresis and any pulse-width qualification. Check whether a pulse narrower than the qualification interval is intentionally ignored, and whether a slow threshold crossing generates multiple events. Preserve sufficient pre-event data to distinguish a source disturbance from a specimen transition.

Use a known electrical challenge to verify the selected condition across the duration boundary. An edge trigger may capture the first transition but truncate the recovery if the record is too short. A pulse-width trigger can classify durations differently depending on whether it triggers during or after the pulse. The instrument manual and challenge result determine the actual semantics.

Treat truncated events as incomplete duration observations

An event already active at the start of a record has an unknown onset. An event still active at the end has an unknown recovery. Preserve these as bounded observations rather than assigning the record length as the physical duration. Store raw timestamps and an explicit onset-complete and recovery-complete flag.

If successive waveform segments overlap, avoid counting one interruption twice. If they are separated by blind time, do not join them automatically into one long event. A continuity monitor or independent time marker may resolve the gap, but interpolation cannot. The event ledger should retain enough information to reproduce the grouping rule later.

Verify counting and timestamps with a controlled challenge

Use an authorized low-energy interruption simulator or representative electrical surrogate, not deliberate damage to customer circuits. Apply isolated pulses, closely spaced pulses and long interruptions spanning more than one record. Compare the independently commanded timing with saved waveforms and the exported event list.

Exercise the path through storage as well as the trigger display. A displayed event that is not written to the final dataset is still missing from the investigation record. Include memory-full behavior, reconnection and restart in the challenge. The simulator validates acquisition logic; it does not prove that every physical via fault has the same waveform or amplitude.

Align events with stimulus without assuming causation

Record chamber temperature, fixture motion or other approved stimulus on a traceable time base. Preserve the difference between commanded stimulus and measured specimen condition. A chamber setpoint step is not the instant at which a ceramic via reaches its highest strain or temperature.

Compare repeated events by specimen coordinate and stimulus phase, while retaining runs with no event and their valid coverage. If every capture occurs immediately after fixture movement, inspect lead restraint and contact stability before attributing the interruption to the buried interconnect. Correlation selects a useful next test; it is not a complete root-cause finding.

Protect the intermittent condition during investigation

Photograph the fixture and contact locations before changing probe pressure, cleaning the specimen or reseating connectors. Save raw data before any smoothing or threshold adjustment. A transient may disappear after handling, leaving the original capture as the only evidence of the as-found condition.

Separate non-destructive localization from authorized physical analysis. A continuous low-stress reading after disassembly does not erase a previously documented interruption. Conversely, a new fault introduced by sectioning or aggressive probing must not be merged with the original event. Keep a chronological action ledger alongside the waveform ledger.

Report what was observed and what remained unobserved

Summarize total elapsed time, qualified observation time, longest blind gap, capture threshold, duration resolution and number of complete and incomplete events. State whether event counts were deduplicated and how. Keep the minimum and maximum observable duration limits close to any duration summary.

Do not extrapolate a short zero-event run to service lifetime, or compare two event rates without comparable coverage and stress conditions. A useful conclusion may be that an intermittent event was localized to a defined electrical boundary, or that the acquisition needs improvement before a negative result is meaningful. Both are more actionable than an unexplained pass label.