Since I have lived through and been part of it, I would like to suggest a technological change that has occurred in the PWB manufacturing industry: I'm sure other people can offer many others. 1. During that time frame (1988 to the present), aqueous processible, liquid, photoimageable (LPI) solder masks have grown from a small foothold of the market in North America to domination of the market. This growth has come at the expense of solvent processed LPI masks, thermal cure and UV cure masks and the dry film solder mask types. At this point, by far the majority of square footage of circuits boards produced in North America are coated with LPI solder masks. To support this huge growth, there has been a substantial growth in equipment for applying and processing these masks, such as: A. Vertical, double sided screening machines have become the dominant method for applying these LPI masks, although there has also been growth in alternative application types, such as spraying, electrostatic spraying and curtain coating. B. Tunnel drying and curing ovens. These support rapid and consistent drying and curing of the LPI masks. C. High powered exposure machines (6, 7 & 8 KW). These provide much quicker exposure times for the LPI masks, plus less heat buildup, phototool distortion, phototools sticking to the masks, etc. Although there have been other technological changes that have occurred in PWB manufacturing overthe past 10 years (direct plate systems, liquid, primary image photoresists, reducers for oxide, etc., I can think of none that have had the same kind of revolutionary impact on PWB manufacturing as the aqueous LPI masks. It seems to me they are akin to other revolutionary types of technologies in the past, such as dry film photoresist, electroless copper, acid copper sulfate plating copper, SMOBC, etc. I would be very interested in other people's experiences and opinions and I can't wait to see the CircuiTree article. Hope this helps. Larry Fisher Dexter Electronic Materials [log in to unmask]