Plastic and nonmetallic article shaping or treating: processes – Laser ablative shaping or piercing
Patent
1991-02-26
1996-01-30
Vargot, Mathieu
Plastic and nonmetallic article shaping or treating: processes
Laser ablative shaping or piercing
264154, 264156, 264482, 21912171, 21912172, B23K 2600
Patent
active
054878527
DESCRIPTION:
BRIEF SUMMARY
This invention relates to laser-machining of polymeric materials and to laser-machined articles so produced.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 4,617,085 describes a method for removing organic material from an organic film by ablative photodecomposition using ultraviolet light of wavelength 193 nanometers from an ArF excimer laser. The rate of removal is said to be substantially enhanced by the use of polymer blends or copolymers in which aliphatic vinyl polymer units such as acrylates or methacrylates, are present together with aromatic vinyl polymer units having pendant aromatic rings, such as styrenes, vinyltoluenes or vinylbiphenyls.
SUMMARY OF THE INVENTION
The present invention relates to classes of polymers possessing superior laser-machining characteristics, optionally together with advantageous equipment and/or wavelengths, to produce laser-machined articles with reduced (preferably without) charring of the polymer. Absence of charring is advantageous since char tends to contaminate the surrounding polymer surface, making clean processing very difficult, e.g. for electronic microcircuits.
A first aspect of the invention accordingly provides a laser-ablation-machined article at least partly composed of (a) aromatic and/or amorphous polyamide material, or (b) polymeric material having repeating in its polymer backbone aromatic rings and aliphatic chains (with the proviso that the aliphatic chains have at least 4, preferably at least 6, more preferably at least 8, carbon atoms when the material is a polyester, and preferably in all cases). A second aspect of the invention provides a method of making an article of polymeric material comprising laser-ablation-machining a body of polymeric material at a laser wavelength, power density, and energy fluence to remove portions of the said body, the said body being at least partly composed of (a) aromatic and/or amorphous polyamide material, or (b) polymeric material having repeating in its polymer backbone aromatic rings and aliphatic chains (with the proviso that the aliphatic chains have at least 4, preferably at least 6, more preferably at least 8, carbon atoms when the material is a polyester, and preferably in all cases). Polyesters will preferably have in the backbone an aliphatic chain of at least 4 carbon atoms between each aromatic nucleus in the backbone and the next aromatic nucleus in the backbone.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
It will be understood that many of the polymeric materials used in the articles or methods according to this invention have aromatic rings in the polymer backbone chain, which gives the present polymers characteristics different from those of the class of polymers with merely pendant aromatic rings described in the aforementioned U.S. patent. The present polymers are well suited to laser-ablation-machining or processing, by which term is meant any process of forming, shaping, cutting, perforating, etching, marking, patterning or otherwise altering any physical dimensions of a body of polymeric material by applying laser radiation thereto so as to cause ablative photodecomposition of the polymeric material, the radiation being either in a narrow beam or spread over a wider area.
The laser radiation may be of any wavelength capable of producing the desired ablation machining effect, and references hereinafter to the laser radiation as "light" are not intended to indicate any specific range of radiation wavelengths. Ultraviolet laser light is preferred, especially at wavelengths below 400 nanometers. Wavelengths of particular interest include those produced by excimer lasers, for example 351, 337, 308, 249, 222, 193 and 157 nanometers, the choice depending to some extent on the application. For example, 193 nm allows resolution of very fine details, while wavelengths of 248 nm or more, preferably of 308 nm, permit wider choice of optical media and need not be transmitted in vacuo, since they are not significantly absorbed by air. Light of 308 nanometers wavelength, preferably from an XeCl
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Ludden Michael J.
Penneck Richard J.
Smith Nicholas J. G.
Burkard Herbert G.
Novack Sheri M.
Raychem Limited
Vargot Mathieu
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