Shin Etsu MicroSi X-23-8195-4 Thermal Compound Review – Hyped in China Reviews and landed in Reality

1 - Introduction and overview 2 - Microscopy, particles and material analysis 3 - Performance comparisons and measurements 4 - Durability (pump-out) and conclusion 5 - Shin Etsu MicroSi X-23-8195-4 vs. Thermal Grizzly Duronaut

If you rummage in the gray area between OEM production line and overpriced retail shelf, sooner or later you will come across the name Shin-Etsu. If you expect more from thermal pastes than just a bit of white blob from a questionable syringe with gaming lettering, you will eventually end up with one of the world’s largest specialty chemical companies – not because of big words, but because of small details. Shin-Etsu Chemical is no newcomer to the world of heat dissipation. In fact, its pipelines have been producing semiconductor-compatible materials for decades, which are more likely to appear in clean rooms than in review tables. The paste with the cryptic abbreviation X-23-8195-4 is one such candidate – a product that almost nobody officially knows about (yet), but which is already working reliably in numerous industrial devices, servers and OEM heat sinks. No marketing, no LED compatibility, no animal in the name – but a silicone-based matrix designed for continuous thermal operation.

Shin-Etsu Chemical Co., Ltd. is a Japanese chemical company headquartered in Tokyo and founded in 1926. Originally started as a manufacturer of nitrogen fertilizers, the company developed into one of the world’s leading suppliers in various chemical sectors. Today, Shin-Etsu is the world’s largest manufacturer of polyvinyl chloride (PVC) and silicon wafers for the semiconductor industry, with production facilities in 17 countries around the globe and over 100 subsidiaries. In addition to PVC and semiconductor silicon, Shin-Etsu also produces a variety of specialty chemicals, including silicones, quartz products and functional materials for the electronics industry, such as this thermal compound. What got me going, however, was the hype that could be found in Chinese forums after tests.

The Shin-Etsu MicroSi X-23-8195-4 was first spotted in retail stores here in April 2025 and it is reported that the paste was only available from one specialized supplier at that time. However, prior to its retail availability, the X-23-8195-4 was already being used in OEM applications andis a further development of earlier Shin-Etsu products such as the X-23-7921-5 and the X-23-7783D. It was developed to offer a slightly lower minimum layer thickness and lower thermal resistance, making it particularly suitable for applications with limited space and high thermal requirements. However, Shin Etsu has deliberately exceeded a minimum thickness of 15 µm and I will explain why today.

So the question is: what’s in it, how well does it spread, and what happens if you try to squeeze the stuff between the IHS and the radiator like a conventional paste? BLT (Bond Line Thickness) is a particularly divisive issue – as are the fingers of those who have to apply it. The X-23-8195-4 promises little according to the data sheet – and says a lot between the lines. Spherical fillers, no electrical conductivity, no obvious tendency to pump-out or siloxane outgassing. Instead, a behavior that seems almost predictable under real pressure load – at least if you don’t confuse the term medium viscosity with “liquid”. Because here, the force-displacement behavior is more decisive for performance than any laboratory specification in watts per something. I will also write something about this.

It belongs to the class of silicone-based high-performance pastes with a ceramic filler structure and has been optimized in particular for applications in which both a low thermal contact resistance layer (BLT) and long-term chemical-thermal stability are required. The formulation is based on a polydimethylsiloxane-containing matrix into which spherical ceramic fillers with high thermal conductivity are incorporated. The paste is characterized by a medium viscosity level with thixotropic flow properties. This makes it easy to dose and apply in a controlled manner, but it remains dimensionally stable under temperature and time. The typically specified thermal conductivity is around 4.6 W/m-K, although this value can certainly be achieved under practical conditions due to the high packing density of the fillers. But I’m still testing that.

The X-23-8195-4 was originally designed for BGA, GPU and flip-chip packages and is now also used in automotive and server platforms where low thermal resistance and electrical insulation are essential. It is not electrically conductive, largely bleed-free and resistant to thermomechanical pump-out, which makes it ideal for use under cyclical loads. The combination of factory-controlled particle size distribution, high purity and defined compressibility makes it one of the most frequently used OEM paste solutions in professional assembly scenarios. In particular, its good long-term stability at layer thicknesses below 50 µm sets it apart from many competing mass market products. And we will see in today’s test that this is not just empty marketing talk. But is this paste also THE high-flyer, as it is already being hyped in some forums?

Test setup and methods	Material analysis and microscopy	Basic knowledge
Here you can find out why effective thermal conductivity and bulk thermal conductivity can be completely different in practice, what role the contact resistance between the surfaces and the paste plays and how thermal compound can be measured precisely. There is also a detailed description of the equipment, the methodology and the error tolerances.	You will learn how laser-induced plasma spectroscopy works and the advantages and limitations of the measurements. There is also high-resolution digital microscopy and analysis of particle sizes. This information is also used to estimate the long-term stability of a paste.	Anyone who has always wanted to know what is or is not in a paste and how these pastes are produced will find what they are looking for here. The basic article provides a better understanding of what is often sold for far too much money and sometimes with adventurous promises.