Photo resist makes LDI a fast, practical, cost-effective alternative for fine line PCB production

Circuit World

ISSN: 0305-6120

Article publication date: 1 June 2000




(2000), "Photo resist makes LDI a fast, practical, cost-effective alternative for fine line PCB production", Circuit World, Vol. 26 No. 2.



Emerald Group Publishing Limited

Copyright © 2000, MCB UP Limited

Photo resist makes LDI a fast, practical, cost-effective alternative for fine line PCB production

Keywords Shipley Ronal, Lasers, Direct imaging, Photoresists

Shipley Ronal is launching the first in a series of photoresists for use with laser direct imaging (LDI) techniques. ultraDIRECT is an acid-etch dry film resist which offers excellent initial and fine line adhesion with good lamination characteristics. It exhibits fast, clean developing and good acid etch resistance. Not only is ultraDIRECT one of the first laser imageable resists to be commercially available in Europe, it is the highest performing on the market.

Long predicted as a technology for the future, LDI is starting to come into its own as a practical method of imaging very fine line PCB designs. Elimination of artwork and contact printing improves yields, facilitates manufacture of very fine line features, and speeds production, especially for prototype and low volume runs. In development of its LDI range, Shipley is working closely with laser equipment manufacturers and leading PCB fabricators already using LDI techniques.

ultraDIRECT offers fast imaging and faster, cleaner developing than any competitive LDI resist. Exposure energy required is 12-14mJ/cm2; that is equivalent to an exposure time of about 15 seconds for an 18 x 24 inch (450 x 610mm) panel. With additional handling time required by the LDI machine, total imaging time is about the same, or faster than that required for contact printing.

ultraDIRECT develops very cleanly, and is capable of a post-exposure hold time of up to seven days if required. lt features good adhesion to copper, good lamination characteristics and it produces a well-defined phototropic image. Acid etch resistance is very good in cupric and ferric chloride based etchants (< 3N HCL), with fast and clean stripping, even in caustic based stripping solutions.

Successful imaging of line and space resolutions as fine as 50 microns is achievable with ultraDIRECT and LDI. First pass yield improvements of five per cent or more (over contact printing methods) are reported by manufacturers using LDI techniques for fine line imaging. These results and a wide process latitude make ultraDIRECT a practical solution for LDI imaging.

For further information please contact: Chris Milton, Shipley Ronal. Tel: +44 (0) 24 7665 4420; Fax: +44 (0) 24 7665 4458; E-mail: or Rachel Redshaw, Shipley Ronal. Tel: +44 (0) 24 7665 4400; Fax: +44 (0) 24 7665 4458; E-mail:

Shipley Ronal - background information

Shipley Ronal is a world leader in the manufacture and supply of imaging technology, specialist chemicals and proprietary plating process additives to the printed circuit board, connector and semiconductor packaging and finishing industries.

Technologies for printed circuit boards include liquid and dry film photoresists for imaging, electroless, electrolytic and direct plating systems, etchants, soldermasks, inks and final finishes. For the demanding semiconductor and connector markets, Shipley Ronal provides gold, palladium and other precious metal plating solutions, complemented by imaging and plating processes for lead frames and other packaging applications.

In addition, Shipley Ronal serves decorative and general metal finishing markets with a wide range of metal and precious metal solutions, as well as a full precious metal recovery service through its refineries.

Shipley Ronal's European headquarters is located in the UK, with local facilities in Germany, France, Italy, Switzerland, Sweden and Benelux. A complete network of distributor partners ensures full coverage of all countries in Western and Eastern Europe.

Shipley Ronal was formed in 1999 by the combination of Shipley's Printed Wiring Boards Division, LeaRonal, Inc. and Morton Electronic Materials. Shipley Ronal is a division of the Shipley Company, a wholly owned subsidiary of Rohm and Haas.

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