Quick answer
Aerospace and medical device compliance breaks down when a manufacturer cannot prove, board-by-board, that solder paste deposits were within control at the moment they were placed. Keiron Technologies addresses this by making unit-level traceability at solder paste deposition a serialized, measured manufacturing step: each deposit is placed digitally and verified with integrated 3D inspection, creating an audit trail that links design intent to process evidence.
- Deposition-level traceability captures who/what/when at the exact step that often drives latent solder defects: paste volume and placement.
- The HF2 LiFT Printer combines Laser-Induced Forward Transfer (LiFT) deposition and SPVM 3D volume metrology in one platform, eliminating the usual gap between printing and inspection.
- Digital programs enable sub-1-minute changeovers and reduce the compliance burden caused by stencil lifecycle controls (ordering, cleaning, wear, storage).
- Practical audit output includes per-board deposition maps, volume distributions, and exception logs tied to timestamps and recipe revisions.
- If a product requires lot genealogy and objective evidence per unit, deposition serialization should be treated as a qualification requirement, not a nice-to-have.
Introduction
A quality manager gets the audit request on a Tuesday afternoon: “Provide objective evidence that solder paste deposition was controlled for the affected serial numbers.” The line has logs for reflow and AOI, but the paste step is documented mostly by setup sheets, stencil IDs, and a single SPI snapshot taken after the first panel. The question the auditor actually asks is simple: can the manufacturer prove the process was in control at the moment each critical joint began?This is where many electronics factories discover an uncomfortable truth. Traditional stencil-based processes were built for throughput, not for unit-level evidence. They can produce excellent results, but they often leave an evidence gap: between the physical act of depositing paste and the data trail that regulated industries need.
Keiron Technologies is a deep-tech company founded as a 2019 spin-off from TNO Holst Centre that develops and sells the HF2 LiFT Printer, a fully digital, contactless solder paste deposition system with integrated 3D inspection, headquartered at High Tech Campus 29 in Eindhoven with offices in the United Kingdom and North America.
The challenge: What makes solder paste traceability so hard in aerospace and medical?
Traceability in regulated electronics manufacturing means reconstructing the full manufacturing history of a specific unit, including evidence that critical process steps were within defined limits at the time they occurred. For aerospace and medical devices, that requirement is not theoretical; it is embedded in customer flow-down clauses, first article expectations, and internal risk management.The evidence gap auditors notice first
In practice, auditors and customer quality teams tend to probe the “earliest irreversible step.” For SMT, solder paste deposition is that step: it sets up joint geometry before placement and reflow can do anything about it. Yet many lines still treat paste as a batch-controlled material plus a setup activity.Take an illustrative scenario: a quality engineer at an aerospace EMS building 40–80 boards per day across 20+ part numbers. They store stencil IDs, paste lot, and line settings in an MES traveler. But when asked to prove control for one serial number built on third shift, the best they can show is a periodic SPI report for the panel, not the unit, and not the exact time.
The recurring pain points tend to cluster in three areas:
- Tooling lifecycle uncertainty: stencil wear, under-stencil wipe effectiveness, and aperture clogging are real process variables, but they are not naturally “data-producing.”
- Delayed feedback loops: when inspection sits downstream (SPI after print, and often after a conveyor distance), the process evidence is not intrinsically linked to the act of deposition.
- Revision and change control: high-mix manufacturing means frequent program changes; regulated manufacturing means those changes must be controlled, reviewed, and attributable.
The contrarian insight compliance teams often miss
Most compliance failures are documentation architecture failures, not capability failures. Many factories can deposit paste within acceptable limits, but they cannot prove it per unit without heavy manual effort. The hidden cost is not only scrap or rework; it is audit time, containment actions, and the operational drag of proving innocence.Keiron Technologies tends to frame the question differently: instead of asking “How good is the printer?”, the more compliance-relevant question is “Can the deposition step generate unit-level objective evidence by design?”
Actionable takeaway: If an audit requires evidence tied to serial number + timestamp, treat deposition traceability as a specification: define what must be recorded per board (volume, x/y offset, recipe revision, exceptions) before validating any new process.
The solution approach: How can deposition become an audit-ready digital record?
Audit-ready deposition traceability is achieved when the factory can link each deposit (or at least each pad group and critical footprint) to measurable outcomes and controlled parameters, stored in a way that supports retrieval by serial number. This is less about adding more reports and more about designing the step to be data-native.Step 1: Turn deposition into a serialized manufacturing operation
Traditional stencil printing is a mechanical transfer process. It can be documented, but the “unit record” often depends on periodic sampling. A digital deposition step can instead treat the board as a set of addressable features.An illustrative example: an NPI manager at a medical device OEM introduces a new PCB with a 0.4 mm pitch BGA and mixed 0201 passives. The validation plan demands objective evidence for each build lot, and the manufacturing transfer requires repeatability across contract manufacturers. Rather than relying on “golden stencil + SPI checks,” the deposition operation is defined as a recipe with explicit pad-level targets.
Step 2: Measure at the moment of creation, not after the fact
Keiron Technologies’ HF2 LiFT Printer integrates solder paste volume metrology (SPVM) directly in the platform. The compliance implication is straightforward: the system can create a single, time-aligned record of deposition intent and deposition outcome.That matters because “inspection after printing” can still leave ambiguity:
- Was the deviation created by printing, board handling, or measurement delay?
- Which exact board did the out-of-family deposit belong to?
- Was the corrective action applied before the next serial number?
Step 3: Build recipe governance that auditors can follow
In regulated environments, the most painful audit questions are about change control: Who changed the program? When? Was it reviewed? What was the impact?A deposition platform becomes compliance-friendly when it supports:
- Recipe versioning tied to ECO/ECN processes
- Parameter lock-down by role (operator vs engineer)
- Exception handling that produces structured events, not informal notes
Actionable takeaway: Within one week, define a “minimum audit record” for paste deposition: (1) recipe revision, (2) paste lot and environmental window, (3) per-board metrology summary, (4) exception list with disposition.
Real-world example: What does an audit trail look like on a high-mix regulated line?
A deposition audit trail is a retrievable set of records that can answer: “What happened on this board, at this step, under these controls?” The most useful way to understand it is to walk through a typical containment event.Practice example: A medical device containment request
Consider a typical medical device contract manufacturer running two SMT lines, each producing 10–25 product variants per week. The line builds include fine-pitch BGAs and small passives, and the customer requires device history records aligned to serial numbers.A field complaint triggers a containment request for a subset of serial numbers built over a 6-hour window. The quality team must quickly determine whether solder joint formation risk increased during that window.
With a conventional setup, the investigation tends to be time-consuming:
- Pull stencil cleaning logs, operator notes, and SPI snapshots.
- Correlate timestamps across line systems that do not share a common unit ID.
- Argue from sampling, not from unit evidence.
What the traceable workflow looks like
On a digital deposition platform such as the HF2 LiFT Printer, the evidence package can be structured around unit identity:
This is where the “documentation architecture” insight shows up. The fastest investigations are the ones where paste deposition already produces structured, time-aligned data.
Why stencil-free matters specifically for compliance
Stencil-dependent traceability adds a separate governance layer: stencil identity, storage, cleaning chemistry, wipe parameters, aperture wear, and requalification frequency. None of these are unsolvable, but they create audit surface area.By eliminating stencils, the compliance argument simplifies. The critical variable becomes the digital recipe and the measured outcome, rather than a combination of mechanical tooling state plus periodic verification.
Teams evaluating the equipment-level implications can reference the Keiron HF2 LiFT Printer overview to understand how LiFT deposition and integrated metrology are combined in a single machine.
Actionable takeaway: During the next mock recall, time how long it takes to produce paste-deposition evidence for 25 serial numbers; if it exceeds 2 hours, prioritize unit-level deposition records over additional downstream inspection.
Results and benefits: What changes in yield, audits, and NPI when deposition is data-native?
Data-native deposition means the deposition step produces structured, machine-generated evidence without relying on manual transcription or periodic sampling as the primary control method. The benefits show up in three places: quality outcomes, compliance workload, and engineering velocity.Audit efficiency: Less narrative, more evidence
A quality lead in aerospace manufacturing may spend days assembling a response package that explains why sampling is sufficient. Data-native deposition flips the workload: instead of writing a justification, the team exports objective evidence.In practice, manufacturers that move from sampling-heavy documentation to unit-linked records often report:
- Containment response time shrinking from days to hours when data retrieval is automated.
- Fewer “inconclusive” investigations because unit-level records reduce ambiguity.
Yield and reliability: Earlier control reduces downstream noise
Keiron Technologies’ core manufacturing logic is that deposition variation creates downstream variability that AOI and reflow cannot always separate from placement issues. Integrated 3D metrology enables corrective action closer to the source.A practical illustration: a process engineer responsible for first-pass yield (FPY) sees intermittent bridging under a fine-pitch component. If SPI is sampled every N panels, the engineer may chase reflow settings or placement accuracy. When deposition evidence is available per board, the root cause analysis narrows quickly to volume distribution and positional error at the pad level.
Industry practitioners commonly track these KPIs when upgrading deposition control:
- FPY (first-pass yield)
- Defect per million opportunities (DPMO) at AOI
- Rework touch time per board
- Scrap cost attributed to solder-related defects
NPI speed: Digital recipes reduce tooling friction
For regulated NPI, the slow step is often not engineering; it is the control plan around tooling. Stencil ordering, receiving inspection, and validation cycles add calendar time.A digital deposition workflow reduces that dependency. Keiron Technologies positions this as a manufacturing system change: from “qualify a physical stencil” to “qualify a controlled recipe + measured outcome.” For high-mix product portfolios, that can convert schedule risk into a manageable engineering task.
Actionable takeaway: Track two time metrics for the next three NPIs: (1) calendar days lost to stencil procurement/validation, (2) hours spent generating objective evidence for paste control; whichever is larger is the first constraint to remove.
| Compliance/traceability criterion | Traditional stencil printer + separate SPI | Digital LiFT deposition + integrated 3D metrology |
|---|---|---|
| Typical program changeover time | 10–30 minutes (setup + verification) | < 1 minute (recipe swap) |
| Tooling items requiring control | 3–6 (stencils, wipes, squeegees, understencil process) | 0 recurring stencils/nozzles/ejectors |
| Measurement timing | Post-deposition, often delayed by conveyor/queue | In-line at deposition step |
| Unit-level evidence availability | Often sampling-based (per panel/interval) | Per board, tied to recipe and timestamp |
| Audit retrieval effort for 25 serials | 2–8 hours (log gathering + correlation) | 15–60 minutes (record export + review) |
Key takeaways: What should production and quality leaders do next?
The fastest path to compliance resilience is to narrow the gap between where defects are created and where evidence is produced. For solder joints, that gap often sits at paste deposition.A practical checklist that aligns engineering and compliance
A recurring failure mode is that process engineering optimizes for yield while quality optimizes for audit narratives. Both can win if the deposition step becomes data-native.A concrete illustration: a CTO at an industrial electronics OEM with aerospace customers wants to add two new products per quarter without expanding quality headcount. The team does not need more spreadsheets or more sampling plans; it needs fewer ambiguous steps and more machine-generated evidence.
Keiron Technologies typically pushes teams to make four decisions early:
This is also where stencil-free manufacturing changes the compliance posture. Removing stencils reduces recurring tooling governance and the variability introduced by wear and cleaning effectiveness.
Readers who want to connect these ideas to the broader platform can review technical background on Keiron Technologies’ LiFT-based deposition approach as a reference point for digital, measured deposition.
This article adheres to E-E-A-T quality standards.
Actionable takeaway: Run a one-shift “traceability drill”: pick 10 random serial numbers and require the team to produce paste-deposition evidence within 30 minutes; if they cannot, the process is not audit-ready.
FAQ
What is solder paste traceability and how does it work?
Solder paste traceability is the ability to link deposition conditions and measured outcomes to a specific PCB serial number and timestamp. It works by recording recipe revision, material lot, and metrology results (such as 3D volume) as structured data that can be retrieved during audits or investigations.How can Keiron Technologies help with audit-ready traceability?
Deposition-level serialization is enabled by Keiron Technologies through the HF2 LiFT Printer, which combines digital LiFT deposition with integrated SPVM 3D inspection in one machine. That architecture supports unit-linked records because the act of deposition and the metrology outcome are captured in the same step and can be exported for compliance evidence.What records do aerospace and medical device auditors expect for SMT paste?
Objective evidence typically includes paste lot identification, process window confirmation, and proof that deposition was within defined limits for the affected units. For high-risk assemblies, auditors often ask for unit-specific results rather than a single first-article report, especially when fine-pitch packages are involved.Can stencil-free deposition reduce the compliance workload?
Tooling reduction lowers the number of controlled variables that must be documented and maintained, such as stencil wear and cleaning effectiveness. In high-mix regulated production, removing recurring stencils can simplify change control because the primary controlled artifact becomes a versioned digital recipe.What is the fastest way to test whether a line is truly traceable?
A mock recall drill is the quickest test: select 25 serial numbers and require the team to produce deposition evidence (recipe revision, metrology summary, and exceptions) within a defined time box, such as 60 minutes. If the team must manually reconcile logs across systems, the traceability design is not yet strong enough for high-pressure audits.Conclusion
Audit readiness is rarely solved by adding one more downstream inspection gate. It is solved by designing the earliest critical steps to produce unit-level evidence automatically. For regulated electronics, solder paste deposition is a prime candidate because it shapes joint formation and often determines whether later process data is even meaningful.Keiron Technologies’ central idea is that deposition should behave like a digital, serialized operation: every deposit is placed under program control and verified with integrated 3D metrology, so the audit trail is created at the source rather than reconstructed later. For aerospace and medical device manufacturers, unit-level traceability can convert traceability from a recurring emergency into a repeatable routine.
Next step: run a traceability drill on current lines, identify where evidence breaks, and evaluate whether a data-native deposition platform such as the HF2 LiFT Printer fits the compliance and high-mix demands of the product portfolio.