Laser etching of polymer masked leadframes

C. K. Ho, Hau Chung Man, Tai Man Yue, C. W. Yuen

Research output: Chapter in book / Conference proceedingChapter in an edited book (as author)Academic researchpeer-review

2 Citations (Scopus)

Abstract

A typical electroplating production line for the deposition of silver pattern on copper leadframes in the semiconductor industry involves twenty to twenty five steps of cleaning, pickling, plating, stripping etc. This complex production process occupies large floor space and has also a number of problems such as difficulty in the production of rubber masks and alignment, generation of toxic fumes, high cost of water consumption and sometimes uncertainty on the cleanliness of the surfaces to be plated. A novel laser patterning process is proposed in this paper which can replace many steps in the existing electroplating line. The proposed process involves the application of high speed laser etching techniques on leadframes which were protected with polymer coating. The desired pattern for silver electroplating is produced by laser ablation of the polymer coating. Excimer laser was found to be most effective for this process as it can expose a pattern of clean copper substrate which can be silver plated successfully. Previous working of Nd:YAG laser ablation showed that 1.06 μm radiation was not suitable for this etching process because a thin organic and transparent film remained on the laser etched region. The effect of excimer pulse frequency and energy density upon the removal rate of the polymer coating was studied.
Original languageEnglish
Title of host publicationSymposium H on Laser Processing of Surfaces and Thin Films
Pages236-241
Number of pages6
Volume109-110
Publication statusPublished - 1 Jan 1997
EventProceedings of the 1996 E-MRS Spring Conference - Strasbourg, France
Duration: 4 Jun 19967 Jun 1996

Conference

ConferenceProceedings of the 1996 E-MRS Spring Conference
CountryFrance
CityStrasbourg
Period4/06/967/06/96

ASJC Scopus subject areas

  • Surfaces, Coatings and Films

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