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SIGEL 8605 Automotive-Grade High-Temperature Resistant Silicone Gel | Potting and High-Temperature Insulation Protection for Power Modules

2026-11-02

Three Major Challenges Faced by High-Temperature Encapsulation Power modules are becoming increasingly compact while operating under heavier loads. For IGBT and SiC power devices as well as new energy vehicle electronic control modules, potting materials are challenged not only by one-off high-temperature shocks, but also by the combined effects of long-term thermal ageing, thermal cycling and electrical stress. Can the potting silicone gel remain soft after continuous ageing at 220°C for 2000 hours? According to ELAPLUS SIGEL 8605 datasheet, after thermal ageing in air at 220°C, the penetration of this material drops from 82 to 72 (1/10 mm), with a change rate of -12.2%, and the weight loss is only 1.6%. These figures provide specific evaluation criteria for material selection for electronic encapsulation in high-temperature zones. Three Major Challenges Faced by High-Temperature Encapsulation 1. Why Should Power Module Potting Not Be Judged Only by Maximum Temperature Rating? Inside the encapsulation cavity of power devices, chips, bond wires, metal terminals and different substrates feature mismatched thermal expansion behaviours. As the module undergoes repeated heating and cooling cycles, the encapsulation material must not only provide electrical insulation and environmental isolation, but also buffer delicate interconnection structures with sufficiently low stress. Ordinary gels may gradually harden, discolour or crack under prolonged high temperatures, losing their original soft buffering capability. Volatiles and material weight loss also deserve attention. Therefore, when evaluating high-temperature silicone gels, penetration, weight loss and electrical performance after ageing should be incorporated into one set of validation logic, instead of making judgements merely based on short-term temperature resistance indicators. 2. Performance of SIGEL 8605 after 2000 Hours of Ageing at 220°C SIGEL 8605 is a transparent two-component addition-curable self-healing silicone gel with a 1:1 mixing ratio by weight. After curing, it forms a soft, transparent gel layer that coats internal chips…

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PVC Wire Harness Debonding After Bending and Ageing Despite Strong Initial Bond: Inspect Interface First, Then the Rigid-Flex Transition of Adhesive Layer

2026-11-02

PVC wire harnesses may pass initial pull tests yet delaminate after repeated bending, vibration or ageing. The root cause is usually not insufficient initial adhesive strength of the structural adhesive. Long-term fatigue reliability depends collectively on PVC surface condition, adhesive flexibility, anchoring length and rigid-flex transition design. The core goal of harness anchoring is to achieve reliable bonding while permitting reasonable cable deformation. Wire harnesses used in industrial equipment, automotive electronics and automated machinery rarely stay static permanently. They are continuously subjected to: Therefore, harness adhesives are not challenged by a one-off static pull force, but by thousands of tiny cyclic displacements. Why a High Room-Temperature Pull Strength Cannot Guarantee Long-Term Harness Reliability Pull tests and real service loading modes for harnesses differ fundamentally. A single tensile test mainly evaluates: Interfacial bond strength. In actual operation, harnesses undergo continuous: Bending, torsion, shear and peel stress. Especially at the adhesive edge, every bend of the cable introduces local peeling stress. Harness anchoring validation should therefore not be limited to maximum pull load; residual interfacial reliability after cyclic bending must also be assessed. Why Surface Condition Matters Greatly for PVC Harnesses Structural adhesive bonds to the outermost surface layer of the PVC jacket rather than the bulk PVC material itself. Different cables vary widely in: Formulation, plasticiser system, surface finish and machining residues. An adhesive performing stably on one cable grade may not work directly on PVC jackets from a different supplier. Re-validation of bonding performance is recommended after changes to: Cable supplier, jacket colour, material grade or production batch. Why Fracture Analysis Delivers More Insight Than Simple Pull Testing After debonding occurs, check which substrate retains the adhesive. Fracture Mode Primary Judgement Next Inspection Focus Most adhesive remains on bracket Harness-side interface failure Jacket surface cleanliness & contamination Most adhesive remains…

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Why Thermal Conductivity Alone Is Not Enough for Transformer Potting Compounds: Winding Gaps Are Narrow — First Verify Whether the Material Can Flow In

2026-11-02

Material selection for transformers and control power supply potting should not rely solely on thermal conductivity comparison. When there are numerous narrow gaps between windings, magnetic cores, pins and PCBs, the priority is whether the material can reliably penetrate these zones and form continuous insulation protection. Even an impressively rated thermal conductivity cannot compensate for internal voids. The interior of a transformer or control power supply is not a simple empty cavity. It typically accommodates windings, magnetic cores, bobbins, lead pins, PCBs and electronic components. The potting compound must flow through many narrow slits, corners and coil gaps. The first question to answer is not “What is its thermal conductivity?” It is: Can the adhesive reach the areas requiring protection? Why Flowability Is Critical for Transformer Potting Potting resin has to navigate intricate internal structures. Insufficient flowability creates this common defect: the surface appears fully filled, while unfilled voids remain trapped inside. Hotspots such as winding roots, the bottom of bobbins, pin surroundings and areas next to magnetic cores cannot be reliably checked only by observing the liquid level. In short: A complete top surface does not guarantee full internal potting. Why Lower Viscosity Is Not Always Better Low viscosity helps penetration into tight gaps, yet transformer potting cannot be judged by viscosity alone. Other key parameters include: Working life, settling stability, dispensing speed, curing profile and final mechanical properties. Blindly chasing ultra-low viscosity without considering mass-production processes may lead to uncontrolled resin run-off, uneven filler distribution and mismatched curing tact time. The proper selection principle: build a viable production process window on the premise of consistent structural filling. Why PUR 1627 Is Worth Evaluating for Complex Transformer Potting ELAPLUS PUR 1627 is a two-component solvent-free thermally conductive polyurethane potting compound, curable at ambient temperature or with heat. Mixed viscosity:…

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Adhesive Selection for Embedded Copper Tubes in Cold Plates: Filling Gaps Is Not Enough. The Core Is to Form a Continuous Thermal Interface Among Copper Tube, Adhesive Layer and Aluminum Plate

2026-11-02

The core purpose of adhesive for embedded copper tubes in cold plates is not simply filling the clearance around copper tubes. It aims to minimise air gaps between tubes and the base plate, enable the adhesive to conform continuously to both copper tubes and substrates, while balancing thermal conductivity, bonding strength, temperature resistance and stability under thermal cycling. If adhesive is only piled on top of the copper tube and fails to flow into both sidewalls and the bottom of the groove, it may look fully filled externally, yet the thermal path is still interrupted by trapped air layers. Heat transfer of cold plates with embedded copper tubes follows this route: Coolant → Copper Tube → Interface → Base Plate. The most frequently overlooked part is the annular interface between copper tube and base plate. Why Interface Treatment Is Still Required Even When Copper Tubes Are Pressed Into Aluminum Plates Mechanical assembly does not guarantee 100% surface contact between copper tubes and grooves. Practical manufacturing tolerances and defects include: After seating the copper tube into the groove, some areas may contact aluminum directly while tiny air gaps remain elsewhere. Air significantly raises interfacial thermal resistance. Therefore, the embedded-tube adhesive converts discontinuous mechanical contact into a nearly continuous thermally conductive contact. Why Dispensing Only a Bead on Top of the Copper Tube Offers Limited Performance Critical voids often do not appear on the top surface. They tend to form at: If the material is overly thixotropic and hardly flows after being dispensed on top, heavy adhesive builds up on the upper surface while voids remain on both sides. Visually the adhesive seems sufficient, but cross-section inspection reveals insufficient filling in the zones that matter most. Desirable Flow Behaviour for Embedded-Tube Adhesive Neither extremely low viscosity nor extremely high viscosity is ideal….

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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…

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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…

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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…

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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…

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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…

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