The dark business with counterfeit thermal pastes – DOWSIL TC-5888 targeted by clone warriors, including a rather well-made clone-copy

1 - Introduction and background information 2 - Chemical analysis and microscopy 3 - ASTM: thermal resistance, conductivity and regression 4 - Charts: measurement curves and temperatures 5 - Summary and conclusion

The demand for high-performance thermal pastes has been high for years, but few products have such a legendary reputation as DOWSIL TC-5888. It is regarded as the reference for thin bondline applications and is used both in industry and in the high-end PC sector. Precisely because the paste is difficult to obtain and Dow has still not managed to provide the necessary safety data sheets and entries in the relevant chemical databases for potential German importers, a veritable gray area has developed around this product.

As a result of this lack of transparency, counterfeiters sense a lucrative business and are becoming increasingly brazen. Their copies are now so convincingly designed that they not only deceive established retailers and companies in Germany, but also private customers looking for supposed bargains on Chinese online platforms. Anyone who buys there runs the risk of receiving inferior goods that do not meet expectations and, in the worst case, can even damage expensive hardware.

In this article, I will show how, with a little luck (and knowledge), such counterfeits can be identified from the packaging using simple means and which methods I use in the laboratory to prove the differences beyond doubt. The aim is to highlight the risks for companies and private customers alike and show how to effectively protect yourself from damage caused by counterfeit materials.

Incidentally, today’s article has a very real background, because it was about an official distributor in Germany, which I was ultimately able to stop and save the not entirely unknown importer from greater damage.

Let’s start with the label on the packaging

The label on the back confirms that this is a “qualified product” and names an internal identifier with the designation QC02 as the tester. The packaging date is given as August 2025. The manufacturer is listed in Chinese as “陶氏化学”, which in China usually stands for Dow Chemical, although there is no evidence of an actual connection to Dow in this context. A “Hebei Lengku Lion Technology Co., Ltd.” is named as the delivering company, the address is Shijiazhuang, Yuhua City District, Tanan Street 39. A telephone number in the Shijiazhuang region is also noted. Q/LKSKJ 002-2023″ is given as the applicable execution standard. A trademark with the lettering “GEEKTC” can be seen on the right-hand side of the label, which is used here as a trademark or bottler’s mark.

As for the bottler itself, Hebei Lengku Lion Technology Co, Ltd, it can at least be said that it is an officially registered company in Shijiazhuang (Hebei province). According to publicly accessible Chinese company databases, it is a supplier of chemical products and materials, although the details are often very general. The company name “冷酷狮” translates as “cold lion” or “cool lion” and the company also sells products under the label “GEEKTC”, which are categorized as electronic accessories and heat conducting materials. However, it is striking that this company is not listed in European databases or by Dow itself as an authorized distributor or licensing partner. This leads to the assumption that it is a non-transparent third-party supplier that bottles materials and resells them under its own brand name.

The company has been registered in Chinese company databases since April 2022, Wu Zengkai is listed as the responsible person and the registered office is located at the aforementioned address in the “Jingcai Center” or “Crystal Center”. The registered business activity is broadly formulated and includes the sale of electronic products, computer accessories, new materials, chemicals without hazardous substance classification as well as import and export; there are also no specific references to authorization by Dow. The GEEKTC brand has its own online presence and positions itself as a supplier and repackager of thermal conductive materials for end customers; the product range extends from thermal pastes and thermal putty to copper cooling kits, and Amazon, AliExpress and Shopee are named as sales channels, among others. So far, so unattractive. There is more information on the other side:

It is worth noting that the activities of this bottler are not limited to sales via marketplaces such as Amazon or AliExpress, but are also aggressively advertised on social media and video platforms. On the YouTube channel operated under the name “极客温控” (GEEKTC), for example, there is a video in which products such as the alleged DOWSIL TC-5888 are showcased and advertised as fully-fledged thermal management solutions for computer hardware.

The cheekiness lies in the fact that a clear proximity to established brand names is suggested here without there being any actual authorization by Dow or a licensed sales partner. While labels already use designations such as “陶熙 (道康宁) TC-5888” and references to “USA, DOWSIL”, this channel goes one step further by publicly advertising these products and thus targeting end customers as well as smaller retailers. Precisely because the packaging and labels appear deceptively genuine to laypeople, there is a considerable risk that private customers and even companies will mistake these products for originals. Advertising via an official YouTube presence further reinforces this impression and makes it clear how professionally counterfeiters are now working to make their products appear credible.

I have deliberately changed the procedure for the following pages. The chemical analysis is carried out first in order to clearly identify the composition and possible deviations right from the start and perhaps also to be able to shorten unnecessary paths. I then turn to microscopy, which makes structures, fillers and surface characteristics visible and supplements the results of the analysis. Only at the end is the time-consuming ASTM measurement carried out to confirm or refute the thermal performance under realistic conditions. In this way, chemical findings, visual impressions and functional testing can be conclusively linked.

	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 paste can be measured accurately. 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.