Recently, the photovoltaic silver paste industry was shocked by a patent invalidation case.

On May 28, 2026, the National Intellectual Property Administration issued two invalidation declaration review decisions successively - No. 660129 and No. 660062. The content of the invalidation declaration review decisions is that two invention patents are all invalid.

The invalidated patents are ZL201180032359.1 (invention name: Thick film pastes containing lead - tellurium - lithium - titanium - oxides and their use in the manufacture of semiconductor devices) and ZL201180032701.8 (invention name: Thick film pastes containing lead - tellurium - lithium - oxides and their use in the manufacture of semiconductor devices). The patentee is Solar Paste LLC, which is a wholly - owned subsidiary of Zhejiang  Solamet, and Zhejiang  Solamet is a holding subsidiary of the listed company DK Electronic Materials (300842 CH). In simple terms, these are two core patents used by DK Electronic Materials to file the invalidation lawsuit. And the company that invalidated these two patents is Zhejiang Gonda Electronic Technology Co., Ltd..

1.What is photovoltaic silver paste?

Photovoltaic silver paste, whose full name is conductive silver paste for solar cells, is a crucial raw material in the manufacturing of photovoltaic cells. Its function is to form metal electrodes on the surface of silicon wafers through processes like screen printing to conduct the current out. Without it, solar panels cannot generate electricity.

This field has three prominent characteristics: technology-intensive, thin profit margins, and high patent barriers.

2.The past and present of the two patents

➡ The original patents of DuPont

The two patents involved in the case - ZL201180032359.1 (invention name: Thick film pastes containing lead - tellurium - lithium - titanium - oxides and their use in the manufacture of semiconductor devices) and ZL201180032701.8 (invention name: Thick film pastes containing lead - tellurium - lithium - oxides and their use in the manufacture of semiconductor devices) - were initially applied for by the American company DuPont in 2011 and belong to the same patent family. They protect the "lead - tellurium - lithium - (titanium) - oxide" technology in photovoltaic conductive silver paste used for sintering through the anti-reflection coating, corresponding to the early paste technology route in the P-type (PERC) cell era.

➡ Zhejiang  Solamet acquires DuPont's business

In February 2021, Jiangsu  Solamet Electronic Materials Co., Ltd., the predecessor of Zhejiang  Solamet, acquired the Solamet® photovoltaic metallization paste business of DuPont for approximately 190 million US dollars, and included hundreds of patents, including the two patents involved in the case, all at once.

➡ DK Electronic Materials acquires Zhejiang Solamet

On May 23, 2025, DK Electronic Materials (300842 CH) held a board meeting and reviewed and approved the motion to acquire 60% equity of Zhejiang Solamet with 696 million yuan in cash. On September 9, 2025, Zhejiang Solamet completed the industrial and commercial change registration and officially became a holding subsidiary of Deke Co., Ltd.

This acquisition is accompanied by a performance commitment: The cumulative net profit of Zhejiang  Solamet from 2025 to 2027 is not less than 287 million yuan.

3.Five lawsuits in five years: Claiming nearly one billion

Since 2021, DK Electronic Materials and its subsidiary Zhejiang Solamet have launched five infringement lawsuits based on these two patents. The defendants are all peers in the photovoltaic silver paste industry. Among them, when Changzhou Juhe was sued, it was in the IPO review period on the Sci - Tech Innovation Board. The two parties reached a settlement, and Changzhou Juhe paid a net license fee of about 9.99 million US dollars, and Jiangsu Solamet withdrew the lawsuit. When Gonda Electronics was sued, it was in the critical window period of mergers and acquisitions and reorganizations. Jiangsu Riyu, Suzhou Jingyin, and Zhejiang Kaiying are emerging domestic silver paste enterprises that have risen in recent years.

4. An earth - shattering reversal: Patent invalidation

➡ Invalidation declaration decision

On May 28, 2026, the National Intellectual Property Administration made the No. 660129 and No. 660062 invalidation declaration request review decisions:

No. 660129: Declare the ZL201180032359.1 invention patent completely invalid

No. 660062: Declare the ZL201180032701.8 invention patent completely invalid

The invalidation declarants in both cases are Zhejiang Gonda Electronic Technology Co., Ltd., and the patentee is Solar Paste LLC (a wholly - owned subsidiary of Zhejiang  Solamet).

➡ Why was it invalidated?

The invalidation reasons are all Article 26, Paragraph 4 of the Patent Law - the claims cannot be supported by the specification.

The review logic of National Intellectual Property Administration Ad Hoc Panel  Administration is that the specification only provides 6 examples, but the claims cover a very wide range of glass frit content (as low as 0.25% - 1.13%, as high as 6.81% - 15%). A person skilled in the art cannot expect that the technical effect of "penetrating the anti - reflection coating and providing good electrical contact" can be achieved within the entire parameter range.

In short, the claims of the patent are written too widely, and the evidence in the specification cannot support such a large protection range.

➡ What is the situation now?

On April 21, 2026: Zhejiang Solamet added litigation requests again, adding two other patents ZL201180031184.2 and ZL201811172520.5.

On June 2, 2026, DK Electronic Materials (300842 CH) of Deke Co., Ltd. issued a announcement，stating that it "does not agree" with the invalidation decision and intends to file an administrative lawsuit with the Beijing Intellectual Property Court.

Zhejiang Gonda Electronics filed a lawsuit of "dispute over liability for damages caused by malicious intellectual property litigation" with the Wenzhou Intermediate People's Court, and the case has not been closed yet.

5.Looking at the enterprise patent strategy from the claim of one billion

➡ Pay attention to the patent trends of competitors

DK Electronic Materials  acquired Zhejiang Solamet in September 2025 and started suing everywhere with patents in November. It can be seen how important it is for an enterprise to pay attention to the patent layout and acquisition actions of competitors. Patent early warning is a required course for every technology - based enterprise.

➡ Make good patent reserves before IPO

Don't wait until the critical moment of IPO to find that there are mines under your feet. Do a good job in the freedom to operate (FTO) analysis of products in advance, lay out the technology route in advance, reserve response strategies, and do a "patent physical examination" before application.

➡ Pay attention to whether the patent can stand up

The value of a patent does not lie in "how many people can be sued", but in "whether it can stand up". If Deke builds its own "ammunition pool" (patent pool) on the basis of the original patent and combines punches (litigation + license), the subsequent plot may be reversed.

Article information source:

[1] Deke Co., Ltd. acquires Zhejiang Solamet for 696 million:http://money.finance.sina.com.cn/corp/view/vCB_AllBulletinDetail.php?stockid=300842&id=11260651

[2] Gonda  Electronics counterclaims for malicious litigation:https://finance.sina.com.cn/stock/wbstock/2025-11-28/doc-infyxmrn7539739.shtml

[3] Fuda Alloy terminates the acquisition of Gonda :https://www.163.com/dy/article/KHSNNSMD05118O92.html

[4] DK Electronic Materials (300842 CH). sues Riyu and Jingyin:https://mguangfu.bjx.com.cn/mnews/20260127/1481564.shtml

[5] Patent invalidation declaration decision:http://www.ipforefront.com/m_article_show.asp?id=5831

[6] Analysis of patent invalidation reasons:https://www.163.com/dy/article/KUP649450519875F.html

[7] DK Electronic Materials  announces patent invalidation:https://news.qq.com/rain/a/20260602A0A3QO00

(This article is for learning and communication only and does not constitute legal advice. If there are any mistakes, welcome to correct them.)