EN
8D Corrective Action Report — Membrane Switch Key Failure
| Elementum | Contentum | Elementum | Contentum |
| Report No. | 8D-20260902-001 | Pars No. | Vmanx.1916 |
| Revision / Status | V1.0 / Issued for customer review | Confidentialitas. | Controlled (bilateral communication) |
| Issue Date | 02 September 2026 | Lot / Batch | 24-09-03 |
| Paratum a | Engineering Dept. / Quality Assessment Center | DIES PRODUCTIONIS | 03 September 2024 |
| Clientem | [European Customer] | Productum | Membrane Switch, 6-layer construction |
| Modus Defectionis | Inverted metal snap dome (snap-through) | Ambitus | D0 – D8, full discipline coverage |
Decision Summary (Conclusion First)
The metal snap domes in the returned samples have inverted (snapped through): the pre-formed convex disc has buckled permanently into the concave direction and now rests against the printed contact pad. This single physical condition produces all three reported symptoms simultaneously — loss of tactile feedback, reduced travel, and a permanently closed (stuck-on) circuit.
Conclusio aestimationis: inversio cupolae est eventus mechanicus super-stressus irreversibilis, non modus exaustionis aut aetatis. Lot 24-09-03 transiit testum tactilis et electricae continuitatis 100 % ante expeditionem, quod cupola inversa per definitionem transire non potest; ergo super-stressus post inspectionem exitus introductus est — durante transportu, conservatione, tractatione aut adunatione. VMANX accipit lacunam systematicam identificatam in Quare 4: requisita tractationis cupolae click non satis communicata sunt cum producto. Sectiones D5 et D7 hanc lacunam claudunt ex utraque parte.
D0 Praeparatio et Responsum Ad Urgentiam
| Elementum | Descriptio |
| Symptoma relatum 1 | Nullum feedback tactilis quando clavis actuetur — characteristicum "click" absens est. |
| Symptoma relatum 2 | Responsio electrica continua / perpetua — clavis se habet quasi premeretur (stans in pressu, semper clausa). |
| Symptoma relatum 3 | Minores motus clavis quam in unitate conformi. |
| Actio urgentis 1 | Custos notificatus est ut lotum 24-09-03 statim desineret uti. Executum est. |
| Actio emergentis 2 | Mercēs in transitū et inventārium apud clientem sub quārantīnā positae. Executum. |
| Actio emergentis 3 | Trācēbilitās totius lōtī et investigātiō interna inita. Executum. |
D1 Ūniversālis Ōrdō
| Officium | Functio | Cura |
| Dux Ōrdinis | Ingeniērium Qualitātis | Cōrdinātiō generālis, dominium causae rēctae, auctōrēs 8D |
| Membro | Ingenium | Analȳsis mēchanismī defectūs et contramēnsum dēsignātiōnis |
| Membro | Productio | Trācēbilitās prōcessūs et vērificātiō in cursū |
| Membro | Qualitas Gubernatio | Execution of inspection and confirmation of data |
| Membro | Servitium clientium | Communication with customer and collection of field information |
D2 Problem Description (5W2H)
| Elementum | Descriptio |
| Quid | Failure of membrane switch key. The metal snap dome has inverted (snap-through): the domed centre is permanently buckled downward and the convex arch structure is lost. |
| Cum | Reported on 02 September 2026. Affected units manufactured on 03 September 2024 (lot 24-09-03). |
| Ubi | Customer end-product assembly line and field use sites. |
| CUM | Detected and reported by the customer quality department. |
| Why (effect) | Inversion produces three coupled effects: travel is shortened; the return force is lost, so there is no tactile feedback; the dome centre stays in contact with the circuit layer, forming a permanently closed circuit. |
| How detected | The customer delaminated the switch layers and visually confirmed the inverted metal dome. |
| Quot | Pending customer data — defective quantity and defect rate required (see D8). |
Returned sample, lot 24-09-03 / P/N Vmanx.1916 — both metal snap domes inverted; red arrows mark the affected domes.
The red arrows and dashed circles mark the two metal snap domes on the circuit layer of the returned sample. Both show the inverted condition: the dome centre is buckled into the concave direction and sits permanently against the printed contact pad, which is why the key reads as continuously closed. The lot marking 24-09-03 / P/N Vmanx.1916 at the lower right confirms sample traceability to the reported batch.
D3 Interim Containment Actions
| # | Containment Action | Dominus | Status |
| 1 | Customer instructed to quarantine all remaining stock of the affected lot | CS / Quality | Factum |
| 2 | In-transit goods intercepted and subjected to 100% inspection | Qualitas | Factum |
| 3 | Remaining warehouse stock of the lot segregated and blocked | Horreum | Factum |
| 4 | Replacement lot supplied to protect the customer production schedule | Productio | Continuo |
| 5 | Customer supported in screening and replacing units already assembled | CS / Engineering | Continuo |
D4 Structure and Failure Mechanism Evidence
The product is a six-layer membrane switch. The metal snap dome is retained in a pocket formed by the double-sided spacer (layer 4) and acts against the printed contacts of the circuit layer (layer 5). The backing plate supplied by the customer forms the load-bearing surface beneath layer 6 and is the element that physically limits dome travel.
| Layer | Descriptio | Functio |
| 1 | Graphic overlay, PET 0.15 mm | User interface, printed graphics, environmental seal |
| 2 | Overlay adhesive, 0.05 mm | Bonds the overlay to the layers below |
| 3 | Spacer / fixing layer, PET 0.05 mm | Retains and locates the dome |
| 4 | Double-sided spacer adhesive | Forms the dome pocket and the open-circuit air gap |
| 5 | Circuit layer, PET 0.15 mm (silver / carbon / dielectric) | Printed conductive traces and contact pads |
| 6 | Rear mounting adhesive | Bonds the switch to the customer backing plate |
Metal snap dome — normal (open), pressed (closed) and inverted (failed), with the six-layer construction.
Normal operation. The metal snap dome is a pre-formed convex disc. Actuation causes a controlled elastic buckling event that generates the tactile "click" and bridges the two printed contacts. On release, the stored elastic energy returns the dome to its convex state and the circuit opens. The transition ring at the dome apex is the geometric datum from which the dome radius is developed; any damage to this ring degrades or destroys the return behaviour.
Inversus cupula (clik-per-transitum). Cum vis applicata cupulam ultra suum maximum designatum cursus impellit, arcus flexus est praeter suum limitem elasticum in secundum statum stabilem. Cupula fit bi-stabilis: non revertitur ad statum convexam sed manet concava, cum centrum eius ad stratum circuitus tenetur. Consequentia est amissio simul tactilis feedback, cursus diminutus, et contactus perpetuo clausus — exacte symptomatum series a cliente relata.
Characteristicum criticum: inversio cupulae est eventus mechanicalis super-stress, non modus gradualis usurae aut aetatis. Accidit instantaneo sub unica actuatione super-cursus, ictu, actione flectionis, aut onere compressivo sustentato, et est irreversibilis. Cupula inversa non potest recuperari per ullam actionem in campo et interruptor affectus debet substitui.
D4.1 Analysis quinque-cur
| Nivel | Quaestio | Responsum |
| Cur 1 | Cur cupula inversa est? | Vis actuationis accepit ultra suum maximum designatum cursus. |
| Cur 2 | Cur ad vim super-cursus subiecta est? | The dome lacked adequate rigid backing support while being pressed, so nothing physically limited the deflection at the travel limit. |
| Why 3 | Why was rigid support absent? | During customer-side assembly, handling, transport or storage the support condition beneath the dome did not meet the design requirement — actuation on a non-flat surface, an unsupported gap under the key area, accidental impact, or a sustained compressive load. |
| Why 4 | Why did that condition occur? | Metal snap domes are highly sensitive to the support and loading environment: they must be handled flat on a rigid surface, any bending, back-flexing or impact destroys the mechanical balance, and once over-deflected the dome does not recover. This sensitivity and the resulting handling requirements were not sufficiently communicated in the documentation delivered with the product. |
| Why 5ROOT CAUSE | What is the underlying root cause? | The switch was subjected to mechanical stress beyond the design specification — over-travel actuation, impact, bending or sustained load — during customer-side assembly, handling, transport or storage. This destroyed the dome transition ring and buckled the arch into an irreversible inverted state. The contributing systemic gap on the supplier side is the absence of an explicit, illustrated handling specification delivered with the product. |
D4.2 Cause and Effect Analysis (4M1E)
| Categoria | Causa Possibilis | CENSUS |
| HOMINIS | Actuation or handling on a non-flat surface; panel bent during rework or pick-up | CONTRIBUTING |
| Machina | No rigid backing plate beneath the key area; unsupported gap under the dome pocket | CONTRIBUTING |
| Materia | Incoming dome actuation force, return force and travel verified against specification | Exclusum |
| Modus | No handling specification issued to the customer; no operator training mechanism in place | CONTRIBUTING |
| Environment | Sustained load in transit; flat-stacked packing; impact during handling and storage | CONTRIBUTING |
| Supplier process | Dome placement, lamination and outgoing test at the VMANX facility | Exclusum |
D4.3 Verificatio processus fabricandi VMANX
| # | Verificatio peracta | Resultatus |
| 1 | Inspectio adveniens partis cupolae: vis actuationis, vis reditus et cursus | Omnes parametri intra specificatonem |
| 2 | Controllo in-processu: positio cupolae super tabulas rigidas planas sub requisito definito platformae | Conformis, nulla deviatio annotata |
| 3 | Inspectio exeuntis: testus continuitatis electricae 100% et examen tactuale 100% | 100% successus, nulli reiecti |
| 4 | Examinatio datorum historicae trans alia lota eiusdem familiae producti | Nulla inversio cupolae systematica observata |
Conclusio de tracciabilitate: defectus non ortus est in processo fabricandi VMANX. Omnes unitates partis 24-09-03 transierunt testum tactualem et de continuitate 100% ante expeditionem. Cupula iam inversa format circuitum perpetuo clausum, quod testum continuitatis proferentis detegit et reicit per definitionem — talis unitas transire non potest nec expediri potest. Inversio igitur post inspectionem proferentem accidit.
Praesentatio positionis: finis huius sectionis est definitio factica limitum, non assignatio culpae. Quocumque loco vis mechanica applicata est, VMANX suscipit responsabilitatem pro lacuna systematica identificata in Quare 4 et adiuvare clientem pollicetur ut condicionibus in campo, quae supra-stressum permittunt, occurrat.
D5 Actiones correctivae permanentes
| # | Actio Corrigens | Dominus | Ob |
| 1 | Adde cartam monitionis conspicuam ad omnem pachetum: "Cupula metallica adhaerens — tracta plana super supportum rigidum. Non flecte, non retrorflecte, non percutere, non comprime." | Ingenium / Qualitas | Praesens |
| 2 | Actualizare specificatia produsului si foaia de instructiuni cu un capitol ilustrat dedicat manipularii cupolelor metalice cu clic | Ingenium | Intr-o saptamana |
| 3 | Actualizare ambalaj: amortizare din spuma sus si jos, panouri ambalate vertical pe muchie in loc de suprapuse orizontal pentru a elimina compresia prelungita asupra tastei | Productie / Inginerie | In doua saptamani |
| 4 | Oferta unei optiuni de proiectare: placa de protectie rigida sau rigidizator local deasupra zonei cupolei pentru medii de asamblare solicitante | R&D | Intra mensem unum |
| 5 | Furnizare video de instruire pentru asamblare care demonstreaza manipularea corecta a cupolei, montarea si indepartarea stratului protector | Serviciu Clienti / Inginerie | Intr-o saptamana |
D5.1 Standard de Manipulare — Practica Corecta versus Practica Interzisa
Ghid de manipulare pentru comutatoarele cu membrana cu cupole metalice — practica corecta versus practica interzisa.
| Praxis recta | Practica Prohibita |
| Pone le interruptor plani super un supporto rigide ante omne actuatione. | Nunquam flecte vel plica le panel. |
| Premi verticalmente con le pad de tu digitus, usante solmente le forsa normal de actuatione. | Nunquam flecte le panel super le margine o angulo de un mensa. |
| Manege le panel per su margines externe, nunquam per le area del clav. | Nunquam usa objectos acute o forsa excessive (puncto de stilus, ungue, instrumento). |
| Stora plani con protection de spuma super le area del clav. | Nunquam impila objectos o applica un carga pesante super le area del clav. |
D5.2 Standard de Assembly, Impachettation e Stoccage
Standard laboris pro coniunctione, impachatione et reposito commutatorum membranarum cum cupulis metallicis.
| Scena | Requisitum obligatorium |
| Conventus | Adfige commutatorem ad laminam planam et rigida. Hoc est praecipuum regulativum: lamina subiecta est elementum physicum quod limitat motum cupulae et praecipit inversionem. |
| Conventus | Nullus spatium non subiectum permittitur sub qualibet area clavis. Capsa flexibilis, tenuis aut vacua sub cupula permittit excessum motus et tandem invertet cupulam. |
| Conventus | Absterge pelliculam liberatoriam ab uno angulo sub angulo parvo. Ne unquam trahas pelliculam trans aream clavis, neve plices tabulam in se ipsam dum pellicula removitur. |
| Packaging | Impacha tabulas erigas in orlo, interponens spumas inter singulas unitates. |
| Packaging | Ne congeras neve comprimas. Onus continuatum super aream clavis per plures dies in itinere sufficit ad inversionem cupulae, etiam absque ictu. |
| Custodia | Temperatura 5–35 °C; umiditas relativa RH 40–70 %; evita lucem solarem directam; utere intra 6 menses post acceptationem. |
D5.3 Nota de periculo — Consequentiæ non-completionis
| Actio impropria | Failure Resultans | Recuperabilis |
| Actuatio sine sustentatione rigida | Transgressio domus, inversio, clavis perpetuo adhesa | NO |
| Flectere aut retro-flectere tabulam | Anulus transitionis deformatum, amissio virium reditus et sensus tactilis | NO |
| Objectum acutum aut vis excessiva | Deformatio domus, perforatio strati superioris, damnum contactus | NO |
| Stivatio plana sub onere continuo | Compressio progressiva ducens ad inversionem domus | NO |
| Plicatura stratum circuitus | Microfissurae in tracio argenteo impresso, circuitus apertus | NO |
D6 Implementatio et Verificatio
| Actio | Status | Methodus probationis | Resultatus |
| Cardo monitionis ad confectionem additus | Completa | Examinatio documentorum confectionis | BOM confectionis actualizatus |
| Actualizatio specificatorum et tabulae instructionum | Continuo | Examinatio a cliente et confirmatio | Expectatio responsionis a cliente |
| Progressio confectionis | Continuo | Drop test and stacking / compression test | Test report pending |
| Assembly training video | Continuo | Customer training confirmation | Delivery pending |
| Rigid cover design option | Continuo | Sample build and functional test | Sample evaluation pending |
D6.1 Preconditions for Continued Use of the Affected Lot
Should the customer wish to release any quarantined material rather than replace it, the following engineering preconditions must be satisfied in full:
① Revidere mutatio technica et confirmatio scripta a cliente de methodo examinandae, criteriis acceptationis, et limitibus responsabilitatis.
② Verificatio primi exemplaris: examen tactuale 100% in fixura rigida de referentia, confirmans reditum integri cupolae et nullam reductionem cursus.
③ Verificatio electrica: examen continuitatis in statu divulgato, confirmans nullum contactum perenniter clausum in ullo clave.
④ Inspectio 100% ante divulgationem, cum exemplari retento bilateraliter confirmato ab utroque parte.
Declaratio risici residui: cupola quae partialiter super-deflexa est sed nondum plene inversa non potest fidele detegi per examen tactuale aut per examen continuitatis. Materia examinata igitur portat risicum residuum defectus in campo quod non potest penitus eliminari, et eius acceptatio requirit confirmationem scriptam ab utroque parte.
Planum verificationis continuandae: proximae tres series productionis consequentes inspectionem tactilis et electricae continuitatis 100 % subibunt, cum proposito rate defectus zero. Registrum inspectionis ad clientem mittetur una cum singulis expeditionibus.
D7 Praeventio Recurrentiae
| Ambitus | Cautela Praeventiva |
| Dispositio Horizontalis | Recensere omnes productos continentes cupulas metallicas ad pressionem et diffundere cartam monitionis unificatam atque instructiones tractationis ad omnem numerum partis affectam. |
| FMEA | Adicere modum defectus "inversio cupulae metallicae ad pressionem (snap-through)" ad databasem FMEA, una cum regulis detectionis et praeventionis eius et cum RPN reviso. |
| Planum Controlis | Actualizare Planum Controlis ut includat exigentiam notificantionis clientis pro specificatis tractationis in primo articulo et in omni mutatione impachetandi. |
| Administratio fornicatorum | Consonare criterium inspectionis adveniens cum suppeditatore cupularum et addere experimentum curvae vi-via, ut rigiditas cupulae et limites viae characterizentur, non solum examinentur ad successum vel defectum. |
| Fase Design | Evalua, pro omni novo producto, utrum placula rigida subiacens an structura protectionis in forma cupolae requiratur, et decisionem in recensione designi annota. |
| Customer Communication | Institue periodicas instructiones de normis tractandi et visitationes subsequens, ut conditio montandi in loco clientis verificetur, non supponatur. |
Essentia huius quaestionis est inaequalitas inter characteristicam intrinsecam producti — altam sensibilitatem mechanicam cupolae metallicae — et veram conditionem in campo, scilicet absentiam supporti rigidi definiti. Itaque strategia corrigens non quaerit culpam assignare. Sed inaequalitatem claudit ex duobus lateribus simul: melior transfusio informationis per cartam monitionis, specificatio illustrata et video instructionale, et protectio physica per emballagium adiectum et per designum tegumenti rigidi optionalem. Uterque modus necessarius est; unum eorum solum reliquum periculum relinquat.
Conclusio D8, Recognitio et Confirmatio Bilateralis
Actio recommendata: substituere unitates affectas potius quam eas examinare et liberare. Inversio cupolae est irreversibilis, et cupolae partialiter super-deflexae non sunt fide dignae in detegendo, ideo substitutio est sola via quae plenam fidem campi restituit. Actiones correctivae in D5 eliminant viam recidivae pro omnibus futuris partibus.
Conclusio unius sententiae: cupola inversa est interruptor perpetuo clausus intra productum clientis — fiducia non restituitur per inspectionem, sed per remotionem conditionis super-stress et substitutionem partium affectarum. Qualitas et fiducia sunt fundamenta societatis diuturnae.
Petitio Informationis a Cliente
| # | Informationes Petitae | Scopus |
| 1 | Quantitas defectiva et ratio defectuum pro parte affecta | Implet campum "Quot" in D2 et determinat magnitudinem continentionis |
| 2 | Photographiae aut exemplaria physica ulteriorum unitatum defectivarum | Confirmat num omnes defectus eandem signaturam inversionis habent |
| 3 | Description of the assembly fixture and the backing support beneath the switch | Key evidence — verifies whether an unsupported gap exists under the key area |
| 4 | Transport and storage conditions applied to the lot | Assesses sustained-load and impact exposure during logistics |
| Elementum | Confirmātiō Clientis | VMANX Confirmation |
| Root cause accepted | □ Accepted □ Not accepted | □ Confirmed |
| Disposition of affected lot | □ Replacement □ Screening per D6 | □ Acceptatum □ Non acceptatum |
| D5 correctivae actiones acceptatae | □ Acceptatum □ Ulterius actio requiritur | □ Confirmed |
| Signatura / Dies |
Hoc relatum a VMANX Ingeniorum Departmento / Centro Assessmentis Qualitatis editum est, quod ius interpretationis sibi reservat. Est hoc assessio technica et per se non approbat nec ullam dispositionem materiae affectae liberat.
