Nuomi Chemical SY-166 Thermal Paste Review – Cheap Poser or really cheap Alternative?

1 - Introduction, advertising claims, and technical specifications 2 - Fracture behavior, microscopy, and composition 3 - Performance comparisons and practical measurements 4 - Durability (pump-out), summary, and conclusion

Long-term observation and pump-out test

After completion of the thermal cycles, the tear-off pattern of Nuomi Chemical SY-166 shows a typical pattern for a viscous, weak but particle-rich paste. When the upper copper plate is lifted off, the surface remains almost completely covered, which indicates good wetting. However, there are clearly displaced areas at the edges where the paste has escaped laterally, and a finely roughened structure of microscopic cavities in the center. These micro-craters are caused by the expansion of the binder phase during heating and subsequent shrinkage during cooling. This allows air to be trapped or squeezed out, which leads to the formation of pump-out zones in the long term. The slightly shiny, smooth surface structure also indicates that the matrix partially flowed back during the thermal load, but the agglomerates remained behind as rigid islands. Overall, the tear-off pattern thus confirms the previously measured behavior: good adhesion, but limited structural stability.

The first graph with the bondline thicknesses versus temperature shows that the SY-166 (yellow) already exhibits a clear expansion from around 40 °C before the curve stabilizes above 70 °C. This is indicative of a binder phase with a relatively low glass transition temperature. This indicates a binder phase with a relatively low glass transition temperature, which loses strength when heated and bulges elastically. In comparison, Polartherm X10 (green) remains significantly more compact and changes its thickness only minimally, which indicates a viscosely more stable and mechanically better cross-linked matrix. The DOWSIL TC-5888 (blue) shows the flattest curve and is considered the reference for very low compressibility and high temperature resistance. The Thermal Hero Quantum (red), on the other hand, shows the largest increase and reaches almost 35 µm at 100 °C, which indicates a very soft, thermally expanding base. The SY-166 is positioned in between – more thermally stable than the Quantum, but significantly less resistant than the X10 or the DOWSIL.

The second graph, the percentage expansion of the coating thickness over temperature, illustrates these differences in relative figures. Here, SY-166 shows only moderate dimensional stability with an expansion of around 80 to 90 %, which puts it in the “mediocre durability” category. This means that although it does not completely destabilize under sustained thermal stress, its layer thickness varies significantly, causing the thermal resistance to fluctuate in the long term. The Polartherm X10 remains significantly more dimensionally stable at around 45 % and indicates relatively good durability, while the DOWSIL TC-5888 is almost ideal at less than 25 %. Finally, the Thermal Hero Quantum exceeds 120 % and shows insufficient structural strength. To summarize, SY-166 wets well and remains stable in the short term, but loses consistency in long-term cycles due to its thermal expansion and soft binder structure. This is typical behavior for inexpensive silicone pastes with an unmodified matrix.

Summary and evaluation

After all the tests, the Nuomi Chemical SY-166 presents a surprisingly honest picture for a product in this price range. For less than 3 euros, you get a classic, oxide-based silicone paste with aluminum and zinc oxide filling that is neither spectacularly good nor completely unusable. Its bulk thermal conductivity of around 4.8 W/mK is in the realistic mid-range, and application is also easy as the paste is soft-flowing and easy to spread. In practice, it impresses with good wetting and reproducible contact surfaces, which makes it perfectly suitable for occasional applications.

Its weaknesses clearly lie in its mechanical stability and thermal durability. The paste expands significantly under temperature, loses structure and shows moderate but permanent swelling in the BLT measurement, which can lead to an uneven bondline during prolonged use. It is therefore unsuitable for continuous loads, high pressures or highly cyclical temperature changes. However, in stationary systems or systems used for short periods of time, for example with less powerful CPUs, older graphics cards, consoles or DIY projects, it fulfills its purpose because it cools reliably enough without being chemically aggressive or smelling unpleasant.

It is therefore only a real bargain if you choose the right application: It is too soft and too expansive for professional applications or permanent CPU assembly in the performance sector, but surprisingly usable for simple tinkering or testing purposes. You are not buying a miracle paste with 16.6 W/mK, but an honest 4.8 W/mK solution that exactly reflects its price: technically solid, but with no reserves. If you are looking for a really inexpensive, uncomplicated paste for occasional repairs or comparative measurements, the SY-166 offers a lot of teaching material for little money, but not a long-term product.