Be careful in price comparisons when concerning OSP's. Unlike metallic finishes, its price is frequently figured for board surface square feet(6' for 18"x24")due to relatively high dragout losses, not finished square feet(in most cases, <3'). There are definite benefits in processing for the board shop. It is possible, not recommended, to re-work the product forever, or until you (10's of microinchs a time) etch your copper below spec. Additionally, since it is recommended as the final step prior to bagging, images are processed as images, not panels of 4 of more(for other methods). With every extra image per panel, handling at the board shop will increase, causing non-material operating costs to increase. Once ALL costs are figured, OSP's could be equal to (or better than) HASL dollarwise(depending on product). They do seem better environmentally and have much better planarity than HASL, but I do not think it will warrant cost reduction until it replaces HASL as a board shop's primary solderability preservative. Charles Stuber Chemical Process Engineer Automata 703-450-2600 [log in to unmask] http://www.automata.com ---------- From: TechNet-request To: rbormann Cc: TECHNET Subject: cost of OSP vs HASL PWB coating Date: Monday, September 11, 1995 5:55PM you said in your CircuitWorld Sept 95 newsletter: >Fabrication Costs ... estimated HASL costs $ .75 - 1.00 per square foot > estimated OSP costs $ .35 per square foot >The costs to the PWB fabricator are significantly reduced and the assembler >benefits from increased yields and better product reliabilty. At the recent Surface Mount International Conference, a paper was presented by Ray, Artaki, Wenger, and Machusak of AT&T Bell Labs. They offered the following fab cost comparisons ($/sq. ft.) Imidazole immersion tin HASL Pd/Cu Pd/Ni Au/Ni min .020 .75 1.40 1.40 2.30 2.80 max .050 1.10 2.40 2.40 3.70 4.00 These numbers are actually my interpretation of the graph shown in the paper as published in the proceedings. These figures are a little higher than what your Newsletter showed. I would interperet that for a typical 3 sq ft panel, the cost savings to the fabricator might be 1.90 to 1.20 per sq ft switching from HASL to OSP. If that is the case, a 4 unit per panel might cost the fab supplier say $0.40 less to produce. If I knew I could save $0.50 per unit on buying PWB's (as a PWB assembler), I would be a hero. To date, no supplier of our Company is offering such price reductions. Maybe they will soon, let's hope. Based on early testing we have done of these coatings, I am ready to change when the savings justifies the relatively minor process changes, but probably not until that time. Jerry Cupples Interphase Corporation Dallas, TX