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PCB-Jan2018

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38 PCB007 MAGAZINE I JANUARY 2018 is an issue it could make this deci- sion easier. It may also result in a cost savings over a sepa- rate equipment purchase for each process. Physical Parameters As part of the equip- ment selection process you will need to know the physi- cal dimensions of your prod- uct line. For PCB man- ufacturing, the copper weight is a primary con- sideration, as is the pan- el size. The weight refers to copper thickness on the substrate and typi- cally is expressed in ounces (per square foot), mils, or micrometers. One-ounce thickness = 1.39 mil = 35 micrometers. Generally, in this industry most production occurs on horizontal conveyorized equipment, with the product traveling through each pro- cess chemistry followed by rinsing before the next process chemistry. After the final rinse, some type of air blow-off, forced air dryer, or combination is used to deliver a dry product, ready for inspection, packaging, or movement to the next process. Most manufacturing in this type of system is of panels or sheets, with the product being immersed or sprayed on one or both sides with the process chem- istry, so another impor- tant consideration will be the panel footprint, e.g. 18" X 24" (or in millimeters X millimeters). Conveyor widths are of- fered as narrow as 15 inches and as wide as 80 inches, with 20-inch and 30-inch widths the most common. The overall length of your multi-stage process line is largely determined by the amount of contact time needed in the most critical pro - cess, and by the volume of production per shift needed. The etching step is typically the crux of this decision for most applications. Once the etching time and work volume requirements are known, determination of the line length is straightforward. This type of horizontal conveyor also works quite well with reel-to-reel (or roll-to-roll) pro- cessing, where product to be treated spools off a supply spindle at the start of the process Figure 1: Example of a single-process line with etch (or other process), rinse and dry modules. Figure 2: Schematic of a cupric chloride etch equipment complete with rinse and dry modules.

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