SMT Gasket
This is a patch of conductive silicone foam that can be attached to a PCB using the SMT process.
It has good electrical conductivity and excellent elasticity after reflow soldering and can be used as an EMI shielding ground or as an alternative to mechanical antenna shrapnel.
At the same time, when the whole machine is subjected to external impact force, the product has a buffering function to avoid damage to other components by the impact force.
We independently developed a highly conductive PI film, which is the first in China. The total thickness can be 0.018mm, the surface resistance can be within 0.03Ω (the actual measurement is around 0.01Ω), and 3 related patents have been extended.
| NO | Patent Name |
| 1 | Electromagnetic shielding material based on polyimide film |
| 2 | High temperature resistant double-sided conductive electromagnetic shielding material |
| 3 | High temperature resistant high elastic conductive electromagnetic shielding material |
SMT Gasket Specification
| Item | Unit | Properties | Method |
| Color | --- | Silver | Visual |
| Size | mm | Customizable | --- |
| EMI SE | dB | ＞75 | ASTM D4935-99 |
| Resistance | Ω/Sq | ≤0.03 | ASTM F390 |
| Salt Spray | Ω/Sq | ＜0.06 | ASTM B117-03 |
| Temp. & Humi. | Ω/Sq | ＜0.05 | GB/T 2423.3-2006 |
| Operating temp. | ℃ | -40~280 | --- |
| Hardness | Durometer | ＜50 | ASTM D 2240 |
| Compression | % | 40 | ASTM D3574 |
| Compression Set | % | <8 | --- |
| Welding strength | N | 14-16 | GB/T 13936-2014 |
| Operating freq. | --- | 10MHz ~ 10GHz | --- |
| RoHS & Halogen | --- | Pb, Cd, Hg, Cr+6, PBBs, PBDEs, Br, CI | IEC 62321 |
| Flame retardancy | --- | 94V0 | UL94-2013 |
Specification of tinned SMT Gasket
| Item | Method | Properties | |
| Material | - | Silicone rubber & conductive PI (Au-Sn / Cu plated) | |
| Color | Visual | Silver, Gold | |
| Size | Digital calipers | Customizable | |
| Heat resistance | GB | Max.400℃ | |
| Operating temp. | GB | -40 ~ +280℃ | |
| Corrosion resistance | Material | HIOKI 3540 mΩ HITEST ER | Max.0.1Ω |
| Temp. & Humi. (85℃ / 85%RH) | Max.0.1Ω | ||
| Salt Spray | Max.0.1Ω | ||
| Heat Shock | Max.0.1Ω | ||
| Welding strength | Push-pull test | Min. 1500gf / cm | |
| Compression Set | Press 40% at 70℃ 22h | Min.95% | |
| Resilience | Press 20% at 25℃ 40%RH | Max.1.0kgf | |
| Flame retardancy | UL 94 | UL 94-V0 equivalence | |
| RoHS & Halogen | Pb, Cd, Hg, Cr+6, PBBs, PBDEs, Br, CI | N.D. | |
Specification of Gold plated SMT Gasket
| Item | Method | Result |
| Surface Resistance | HIOKI 3540 mΩ HITEST ER | Pass |
| Heat resistance | 85℃ & 96hr | Pass |
| Cold resistance | -40℃ & 96hr | Pass |
| Temp. & Humi | 85℃ & 85%, 96hr | Pass |
| Thermal Shock | 70℃ & 60min / -40℃ & 60min (30 cycles) | Pass |
| Salt Spray | Spray 5% NaCl, 1.0kgf / cm spray pressure, 35 ℃ for 48 hours, stand for 16 hours. | Pass |
| Compression Set | Press 40% (70℃ 22hr) | Pass |
Reliability test of SMT Gasket
| Product | SMT Gasket | Metal spring Gasket | Conductive cloth Gasket |
| Material | Silicone rubber | Metal | Resin |
| Operation | SMT | SMT | Manual Operation |
| Bonding | Welding | Welding | Adhesive |
| Conduction | ⭐⭐⭐ | ⭐⭐ | ⭐ |
| Performance | ⭐⭐⭐ | ⭐⭐ | ⭐ |
| Contact area | Wide | Narrow | Narrow |
| Size | Customizable | Limit | Customizable |
| Reliability | Better | Easy to break | Easy to fall off |
| Installation time | Less | Less | More |
Comparison of advantages of SMT Gasket, Metal spring Gasket, Conductive cloth Gasket
Reflow temperature curve setting:
Reflow temperature curve setting of SMT Gasket
1. Preheating zone. It is suggested that 150 ℃ should be used, the heating rate should be 1 ~ 1.5 ℃ / s, and the time should be 100 ~ 120s.
2. Activation zone. For different fluxes, the activation temperature is different. The heating rate is recommended to be 0.3 ℃ / s, and the final heating temperature is about 180 ℃. The recommended time is 90 ~ 120s.
3. Fast heating zone. The heating rate is recommended to be about 2 ℃ / s, and the time is recommended to be 15 ~ 20 s.
4. Reflux zone. It is recommended to refer to the data provided by the solder paste manufacturer for the selection of the peak temperature and overall reflux zone time. Different types of solder have different requirements for reflow temperature. The peak temperature is generally 240 ~ 250 ℃. The time of the whole reflux zone is recommended to be 40 ~ 80s. The residence time at the peak temperature is generally less than 10s.
5. Cooling zone. It is suggested that the temperature change rate should be consistent with that in the rapid heating zone, and it is suggested to set it at 1 ~ 3 ℃ / s.
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