• Certification
    ISO9001/ISO14001/IATF16949
    ROHS/UL/REACH/FDA
    Mail Contact
    kennis.zhu@elaplus.cc

    +86 18116225322

    Welcome to be our distributor

Industry Application

Home » Industry Application »

Magnet Bonding for Motors: Initial Pull Strength Passed, Yet Magnets Still Loosen After High-Temperature Operation. Do Not Only Focus on Strength; Inspect Interfaces and Adhesive Layer First

2026-11-02

Motor magnets may pass initial pull tests but loosen after high-temperature operation, vibration or thermal cycling. The root cause is often not insufficient adhesive strength. Long-term bonding reliability depends collectively on magnet surface condition, rotor substrate interface, bondline thickness and curing state. Magnet adhesive selection shall shift focus from “initial strength” to interfacial stability under real working conditions. Motor Magnet Bonding Magnet bonding seems straightforward: securely attach magnets to the rotor. In service, however, the adhesive layer continuously withstands: A passing room-temperature pull test only proves adequate bonding at the initial state. It cannot guarantee that the joint stays intact over long-term operation. Why Is the Bond Strong at Room Temperature But Prone to Failure at High Temperature? When temperature rises, magnets, metallic rotor and adhesive expand at different rates. During operation from cold start to full load, the magnet and rotor expand dimensionally while the adhesive layer is sandwiched between the two substrates. Repeated cycles of start-up → heat-up → shutdown → cooling subject the interface to cyclic stress instead of one-off static tension. Therefore, the critical validation for magnet bonding is: How much bonding performance remains after high-temperature exposure and thermal cycling. Why Do Magnets Keep Detaching at the Same Spot? Recurring failure at a fixed location requires structural and interface checks before switching to higher-strength adhesives. Typical symptoms include: Magnet corners lifting first, consistent edge delamination, repeated failure at the same slot. These usually indicate: If the root cause lies in structural clearance, switching to a higher-grade adhesive will not change the failure location. This is a core principle of ELAPLUS diagnostic selection: investigate structure for fixed-position failures; prioritize material and process for random failures. Why Is the Magnet Surface the First Inspection Item? Structural adhesive bonds to the outermost surface layer of the magnet, not the…

More

Why Does Oil Pressure Sensor Drift After Long-Time Oil Exposure Even If It Performs Well at Room Temperature After Potting? Check Medium Penetration and Interfacial Changes First

2026-11-02

An oil pressure sensor may pass all room-temperature tests after potting, yet develop zero drift, reduced insulation or sealing failure after prolonged contact with hydraulic oil, lubricating oil and other media. Do not only inspect the sensing chip. Instead, verify whether the potting compound absorbs fluid, swells or softens, and check interfacial integrity between adhesive and metal / plastic substrates. The core requirement for sensor potting adhesives is not strong initial adhesion, but stable performance upon continuous medium exposure. A common misjudgment for this failure mode: Passing all factory tests is mistakenly taken as proof that the potting material is qualified. Oil pressure sensors operate under combined long-term loads: Pressure + Temperature + Vibration + Oil medium. Initial performance only proves the material works right after assembly. 1. Why Failures Only Occur After Oil Immersion Rather Than At Ambient Testing Room-temperature tests only reflect the material’s initial state. Long-term medium exposure requires monitoring: For precision pressure sensors, slight swelling or interfacial variation can alter internal mechanical boundary conditions, even without obvious cracking. Conclusion: Intact adhesive appearance is not sufficient evidence of oil resistance. 2. Possible Material Changes After Oil Intrusion Behaviours vary by polymer system, oil type and operating temperature. Four key changes need evaluation: 3. Why Oil Pressure Sensors Are Vulnerable to Minor Swelling General electronic modules mainly concern water ingress and short circuits. Pressure sensors additionally require stable mechanical loading on sensitive structures. If potting material sits close to: Dimensional change caused by fluid absorption generates residual stress. Such stress may not destroy the component instantly, but leads to: Sensor drift and uncracked adhesive can coexist. 4. Distinguish Bulk Material Failure From Interfacial Failure Judge by failure symptoms: Failure Symptom Priority Investigation Key Validation Items Overall adhesive softening Medium resistance of bulk material Hardness & mass change Obvious…

More

Pin Sealing for Automotive Connectors: Why Surface Sealing Alone May Still Allow Water Ingress? Reliable Sealing Must Be Achieved at the Terminal Root

2026-11-02

The key to waterproofing automotive connector pins is not simply covering the terminal surface. Instead, the sealing material must wick into the micro-gap between pins and plastic housing to form a continuous insulating and waterproof barrier at the terminal root. If adhesive only stays on the surface, moisture can still migrate inward along the metal-plastic interface. Dense pin arrays require special attention to material flowability, interfacial adhesion and stress buffering after curing. Pin Sealing A common pitfall in connector sealing is “false sealing”: the surface appears fully covered by adhesive. However, cross-section inspection reveals adhesive sitting on top while water ingress channels remain underneath. Surface photos alone cannot verify connector sealing reliability. 1. Why Hidden Water Ingress Paths Easily Form Around Pins Pins pass through: Long-term waterproofing cannot be guaranteed just by tight contact between metal and plastic. In practice, gaps may arise from: Moisture can gradually travel inward along these interfaces. Therefore, pin sealing is intended to block capillary channels formed at the metal-plastic boundary. 2. Why Water Can Still Seep In Even When Pins Are Covered With Adhesive Coverage and penetration are two different concepts. High-viscosity material may only form a cap on top of pins, presenting a perfectly sealed appearance. Continuous micro-gaps may still remain at the pin root. Once water enters, it propagates along: pin sidewall → housing interior → PCB / terminal area. The primary criterion for pin sealing is whether material penetrates down to the root, not the thickness of the surface film. 3. How to Distinguish Insufficient Penetration From Poor Adhesion Failure Mode Primary Judgment Inspection Method Persistent voids at root Insufficient flow Cross-section analysis Complete delamination from plastic Failed adhesion to plastic substrate Interface peel check Adhesive separates from pins Failed adhesion to metal Plating compatibility check Leakage only after thermal cycling…

More

Why Do Solder Joints Still Fail Under Vibration Even Though FPC Solder Looks Good? The Root Cause May Not Be the Solder Joint Itself, But Unrelieved Harness Stress

2026-11-02

FPC solder joints may show good continuity and acceptable soldering appearance initially, yet fracture after vibration, plugging/unplugging or thermal cycling. The common root cause is often poor soldering quality. Instead, continuous mechanical stress generated by FPC bending and harness displacement concentrates at the root of solder joints. For such failures, solder joint protection should be upgraded from simple coating with adhesive to forming a flexible stress transition zone. UV Adhesive for FPC Reinforcement FPC, flexible flat cables and fine wire harnesses are inherently flexible, while solder joints form rigid connections. The boundary between flexible and rigid materials is naturally prone to stress concentration. This explains why many products pass factory tests but develop intermittent contact failures after prolonged vibration. 1. Why Solder Joints Can Crack Even Without Cold Solder Joints Solder is designed to establish reliable electrical interconnection, rather than to withstand repeated harness bending as a structural component over long service life. When FPC is subjected to: External loads propagate along the flexible circuit to the rigid soldering area. Without stress buffering, the bending neutral axis tends to stay at the solder edge or the root of FPC copper foil. Consequential failures include: A fracture appearing at the solder joint does not necessarily mean the soldering process is defective. 2. How to Distinguish Soldering Defects from Mechanical Fatigue Judge by failure occurrence conditions: Failure Phenomenon Primary Judgment Recommended Inspection Items No conductivity right after soldering Soldering anomaly Wetting, solder material, soldering temperature Normal at rest, open circuit after bending Root stress concentration FPC bending position Intermittent open circuit after vibration test Fatigue failure Solder joint / FPC interface Abnormality after several mating cycles Tension transfer Harness fixation Resistance drift after thermal cycling Thermo-mechanical stress Copper foil, solder joints Failure immediately after adhesive curing Curing-induced stress Adhesive dosage, hardness Repeated…

More

Why Does Insulation Degrade Under High Humidity Even After Conformal Coating on BMS PCBs? Film Protection and Potting Are Not Interchangeable

2026-11-02

If insulation drops on a BMS PCB after conformal coating under high-humidity conditions, the first step is to identify whether moisture penetrates through the material or bypasses the protective layer to reach critical areas. Connector roots, board edges, component undersides, uncovered zones and mechanical damage to the coating can all form moisture ingress paths. For BMS requiring deeper environmental isolation, conformal coating and potting shall be selected according to risk zones instead of simply replacing one with the other. Conformal Coating for BMS A common misconception in BMS protection: A transparent protective film on the PCB surface equals full sealing of the entire control board. In fact, conformal coating delivers thin-film surface protection, while potting provides deep cavity filling, insulation and environmental isolation. They serve different purposes. 1. First Diagnosis: Is the BMS Suffering From Surface Moisture or Boundary Ingress? When insulation degrades after high-humidity exposure, do not immediately increase coating thickness. Locate where failures cluster: The priority is not switching to a better conformal coating. It is to locate the path by which moisture reaches electrically sensitive circuits. 2. Why Moisture Can Still Infiltrate Even With Sprayed Conformal Coating Conformal coating forms a continuous protective film. Take SICOAT 9060-L as an example. It is a low-viscosity one-component silicone protective coating with viscosity of 400–600 mPa·s. It cures into a transparent film for protection of PCBs, ICs and electronic components. Advantages of this coating type: However, a PCB is not a flat glass plate. It carries: Spraying trajectories often fail to cover these 3D geometries and leave weak points. A moisture-resistant material does not guarantee uniform protection across every location on the PCB. 3. Why Connector Roots Are High-Risk Zones for BMS Moisture Protection Connectors create significant geometric shadowing. Spray mist may cover the outer connector housing but cannot fully…

More

Does Foam Material Have to Replace All Potting Adhesives for Battery Module Weight Reduction? Differentiate Filling, Thermal and Structural Functions First

2026-11-02

Battery module lightweighting cannot be achieved by simply replacing conventional solid potting adhesives entirely with low-density foam materials. Foam filling, thermal conduction, structural bonding and insulation protection serve distinct functions. The correct approach is to define zones for cavity filling, heat transfer or load bearing, then adopt a combined solution of PUR 1685 foamed polyurethane, lightweight silicone or standard thermally conductive materials accordingly. Foam Filling for Battery Packs This is one common selection pitfall in battery PACK lightweighting: Lower density does not mean suitability for every adhesive application point. 1. Why Traditional Full-Cavity Solid Potting Adds Weight Suppose a battery module requires filling a large internal cavity. If high-density solid potting material is used for the whole space, greater adhesive volume brings substantial weight gain. For new energy vehicles, drones, mobile energy storage and similar applications, weight directly affects: Therefore, for large-volume potting, a key question arises: does every part of this adhesive really need to be high-density solid material? 2. Four Core Functions of Adhesives Inside Battery Modules 3. Why Foam Potting Works Well for Large-Volume, Non-Critical Thermal Zones Foam materials contain numerous controlled closed cells. At equal volume, less raw material is consumed, which reduces potting weight. PUR 1685 is a 1:1 two-component foamed polyurethane system. Its density after foaming is approximately 0.2 g/cm³ with UL94 V-0 flame retardancy, designed for large-volume filling scenarios requiring lightweighting such as battery modules. This material is engineered to fill large spaces with less material mass, rather than pursuing maximum thermal conductivity. 4. Why Foam Adhesive Cannot Directly Replace Thermal Gel They are designed for different missions. Material Type Primary Function Key Indicators Foamed Polyurethane Lightweight filling Density, flame retardancy, cushioning Thermal Gel Thermal interface Thermal conductivity, BLT, thermal resistance Thermally Conductive Potting Compound Encapsulation + heat dissipation Thermal conductivity, insulation, flowability…

More

Why Creepage and Partial Discharge Still Occur After High-Voltage Module Potting: Full Filling Does Not Equal Reliable Insulation

2026-11-02

Even fully potted high-voltage modules may suffer creepage, partial discharge or even dielectric breakdown. Adhesive coverage alone does not guarantee a continuous, defect-free insulation path inside the assembly. Air gaps at pin roots, electric field concentration at sharp edges, interfacial delamination, residual contamination and insufficient effective insulation distance after potting can all initiate high-voltage failures. For 800 V and higher voltage platforms, potting reliability shall not be judged merely by whether the cavity is fully filled. Instead, evaluation should focus on the electric field distribution and insulation path formed between high-voltage potential points. 1. Distinguish Breakdown, Creepage and Partial Discharge First: Dielectric breakdown means the insulation medium loses its insulating capability. Under strong electric fields, a conductive channel forms within the originally insulating region, which may directly cause a short circuit between high voltage and low voltage. Second: Creepage refers to conductive paths developing along insulation surfaces. Moisture, contamination and ionic residues raise the creepage risk. Even if high-voltage terminals are covered by adhesive, unstable surface or interfacial conditions do not eliminate creepage hazards. Third: Partial discharge takes place locally within the insulation system. It may not trigger immediate complete breakdown. Nevertheless, repeated discharge over time progressively erodes local insulation and eventually leads to severe electrical failure. In short: No short circuit does not mean the insulation system is free from degradation. 2. Why Tiny Internal Voids Matter Greatly for High-Voltage Potting For high-voltage potting, the primary hazard is not limited to large bubbles visible to the naked eye. More risky defects often include: These locations form a discontinuous structure: solid insulation – air – solid insulation. Electric field redistribution occurs accordingly. The real goal of high-voltage potting is continuous insulation, rather than a visually full appearance. 3. Why Pin Tips and Sharp Corners on Busbars Are High-Risk Zones Electric…

More

Why Rain & Light Sensor Sensitivity Drops After Dispensing Adhesive: Transparency Is Not Enough — Bubbles, Adhesive Thickness and Optical Bonding Are the Key

2026-11-02

When the sensitivity of a rain & light sensor declines after dispensing transparent adhesive, the first check should target the optical interface for bubbles, local voids, uneven adhesive thickness and surface contamination, rather than merely checking whether the adhesive is “transparent enough”. For optical sensors, the adhesive layer itself forms part of the light path; any discontinuous interface may alter light propagation. Rain & light sensors form a coupled optical interface with the windshield through their optical structure. One function of transparent gel/silicone is to eliminate irregular air gaps between the sensor and glass. Poor assembly alone can lead to abnormal sensor operation. 1. Why Does the Sensor Become Less Responsive Even With Transparent Adhesive? First: Visual transparency does not guarantee an intact optical interface. A transparent adhesive layer may contain: It may still look clear to the naked eye. But for light travelling inside the sensor, these areas create new refraction and reflection interfaces. Therefore, the main risk for rain & light sensors is not simply “non-transparent adhesive”, but unintended air layers and inconsistent interfaces within the light path. 2. How Can a Tiny Bubble Interfere With Detection? Air and transparent adhesive have different optical properties. Under designed conditions, light is expected to travel continuously: Sensor optical surface → Transparent adhesive layer → Windshield If an air bubble forms inside the adhesive, an extra interface is introduced. This changes local light behaviour including: Ultimately, the signal received by the photodetector will be altered. For rain & light sensors, “no large visible bubbles” is insufficient. Special attention must be paid to the optically active area for: 3. Does More Adhesive Ensure Stable Optical Performance? No. Over-dispensing may cause: Insufficient dispensing, on the other hand, may result in: The target is a stable, continuous and uniform optical adhesive layer, not simply…

More

Why Temperature Resistance Alone Is Not Enough for Pressure Sensor Potting: High-Temperature Performance, Low CTE and Low Stress Must Be Evaluated Together

2026-11-02

The potting of pressure sensors should not be judged merely by the “maximum temperature resistance in °C”. Long-term reliability is actually determined by CTE, modulus of the cured compound, substrate matching, thermal conductivity requirements and stress induced by temperature cycling. Especially for assemblies combining aluminum housing, ceramic, PCB and sensing die, the fact that an adhesive can cure at high temperatures does not guarantee reliability after long-term thermal cycling. Pressure Sensor Potting 1. Why Are Pressure Sensors Particularly Vulnerable to Thermal Stress? First: Thermal expansion of internal materials is inconsistent. A pressure sensor may incorporate multiple components: These components expand to different extents as temperature rises. If the potting adhesive features high thermal expansion and high stiffness, thermal deformation will be converted into mechanical stress. Second: Pressure sensors require not only protection but also stable measurement performance. General electronic modules mainly focus on basic functionality. For sensors, extra concerns arise: Will the encapsulation affect the sensitive structure and output stability? Therefore, “harder equals better” is not a universal rule. 2. What Do Temperature Resistance, Tg, CTE and Modulus Respectively Address? Parameter Core Question to Answer Risks of Improper Selection Operating Temperature Whether the adhesive can withstand the service temperature long-term Aging, performance degradation Tg Whether the material state changes drastically upon temperature rise Variation of modulus and dimensional stability CTE How significantly the adhesive expands and contracts with temperature Interfacial stress, cracking, delamination Modulus / Hardness How much stress the adhesive transfers to components Stress damage to sensing die and solder joints Thermal Conductivity Whether heat can be dissipated efficiently Local overheating Adhesion Whether interfacial bonding remains intact after thermal cycling Delamination, water ingress To sum up: Temperature resistance answers whether the adhesive can survive at a given temperature; CTE and modulus determine whether temperature fluctuations will damage the assembly…

More

COPYRIGHT ◎ 2023 Elaplus Functional Materials Co. LTD

Mail Mail
eddie.zhang@elaplus.cc
 WhatsApp WhatsApp
+86 155 1820 1251
WeChat WeChat
WeChat

sample request

We will reply within 24 working hours. If urgent, please help us to contact through email： kennis.zhu@elaplus.cc