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However, its performance is highly sensitive to the probe-to-sample distance, often requiring extremely close proximity, which limits its practical application in device manufacturing, especially in scenarios involving coatings and packaging. In this study, we propose a distance inversion method based on a dual-port symmetrical microwave probe to improve imaging performance at larger, safer scanning distances. This method utilizes the correlation between probe height and resonant frequency to compensate for distance-induced signal distortions. The experimental results demonstrate that even at a probe\u2013sample distance of 80 \u00b5m, clear and distinguishable NSMM images of printed circuit boards (PCBs) can be obtained. The imaging resolution reached 13 \u00b5m. The defect structure with dimensions of 130 \u00d7 130 \u00b5m2 on the PCB was successfully identified. The signal-to-noise ratio was significantly enhanced after applying the correction method. This approach not only improves the robustness and flexibility of NSMM in industrial scenarios but also extends its applicability to packaged or coated electronic devices, offering a valuable tool for advanced non-destructive testing.<\/jats:p>","DOI":"10.3390\/sym17040561","type":"journal-article","created":{"date-parts":[[2025,4,10]],"date-time":"2025-04-10T05:28:07Z","timestamp":1744262887000},"page":"561","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Effective Enhancement for Printed Circuit Board Imaging in Near-Field Scanning Microwave Microscopy"],"prefix":"10.3390","volume":"17","author":[{"given":"Tao","family":"Zhou","sequence":"first","affiliation":[{"name":"School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Quanxin","family":"Zhou","sequence":"additional","affiliation":[{"name":"School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hao","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Haoyun","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5552-4619","authenticated-orcid":false,"given":"Zhe","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9756-9487","authenticated-orcid":false,"given":"Jianlong","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yubin","family":"Gong","sequence":"additional","affiliation":[{"name":"School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2377-5840","authenticated-orcid":false,"given":"Baoqing","family":"Zeng","sequence":"additional","affiliation":[{"name":"School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,4,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1872","DOI":"10.1063\/1.120444","article-title":"High spatial resolution quantitative microwave impedance microscopy by a scanning tip microwave near-field microscope","volume":"71","author":"Gao","year":"1997","journal-title":"Appl. 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