Cable & EMI Shielding
Cable-shielding tapes live where heat and humidity meet a thin metal layer. Here is how to qualify the adhesive — not just the finished tape — for 85°C / 85% RH service.
Double-85 means 85 °C and 85 % relative humidity, held for a defined duration — commonly 500–1,000 h (ASTM D2247 as a reference for humid aging). For cable-shielding foil tapes it answers one practical question: after prolonged hot, humid service, does the foil-film laminate still hold its bond and its electrical/barrier integrity? That is the condition most likely to drive field delamination, so it is the first screen buyers should require.
| Parameter | Typical range | Common test method |
|---|---|---|
| Adhesive viscosity | 500–20,000 mPa·s | ASTM D2196; ISO 2555 |
| Non-volatile content | 30–100 % (water-based → 100 % solids) | ASTM D2369; ISO 3251 |
| Coating weight | 2–15 g/m² | Internal |
| Initial peel strength | 3–15 N/25 mm | ASTM D3330; GB/T 2792 |
| Final peel strength | 5–20 N/25 mm | ASTM D3330; GB/T 2792 |
| Double-85 peel retention | ≥80–90 % of initial (project target) | Internal + ASTM D2247 |
| Shielding effectiveness | 40–100+ dB (freq/structure dependent) | ASTM D4935; IEC 62153-4-3 |
| Flex durability | 1,000–100,000+ cycles | IEC 62153-4-3; Internal |
Aluminum is unforgiving: a thin metal layer amplifies every coating defect. Map the symptom:
| Failure | Root cause | Corrective |
|---|---|---|
| Foil–film delamination | Foil contamination, poor wetting, adhesive incompatible | Clean/treat foil; verify chemistry; optimize coat weight |
| Metal-layer transfer / separation | Weak metallization anchor; high lamination stress | Verify metallized side; reduce pressure; compatible adhesive |
| Wrinkle / foil break | Tension too high/uneven; misalignment | Balance unwind/rewind tension; guiding and nip alignment |
| Corrosion / discoloration | Residual moisture; pH/ionic incompatibility | Improve drying; verify pH/ion compatibility; humid-age test |
| Shielding attenuation | Discontinuous metal; bend cracking; adhesive bleed | Check continuity; reduce mechanical stress; verify electrical design |
A frequent mistake is to read a high peel number as "good tape." Peel strength is mechanical; shielding effectiveness is electrical (ASTM D4935 / IEC 62153-4-3). A tape can bond strongly yet lose shielding continuity after bending because the conductive layer cracked or the adhesive migrated into the conductive interface. Qualify the two properties independently, and re-measure both after double-85 exposure.
Double-85 means 85°C and 85% relative humidity, held for a defined duration (commonly 500–1,000 h). For cable-shielding foil tapes it screens whether the laminate retains adhesion and electrical/barrier integrity after prolonged hot, humid exposure — the condition that most often drives foil-film delamination in the field.
Root causes are foil contamination or rolling oil, poor wetting, adhesive chemistry incompatible with the aluminum surface, insufficient dry-through, and corrosion from residual moisture or ionic incompatibility. Correctives start with verified foil cleaning/treatment and an adhesive validated for the actual foil-film pair.
No. Peel strength is a mechanical bond property; shielding effectiveness is an electrical property of the continuous conductive layer. They must be measured separately. A tape can have strong adhesion yet broken shielding continuity after bending.
A double-85 test report stating the duration and acceptance criteria, peel-strength data before and after aging, shielding-effectiveness measurement, and a corrosion assessment. Without a complete report, treat any "double-85 passed" claim as unverified and request the protocol and raw data.
Tell us your foil type, carrier film, line speed and target service condition. We'll outline a qualification protocol and share relevant aging data on request.
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