September, 2013
www.us-tech.com Nitrogen Helps Boost SMT Quality Continued from page 58
achieve high-purity nitrogen from a compressed-air source. Similarly, lab- oratory nitrogen gas generators from Cole-Palmer (
www.coleparmer.com) can work with a dedicated com- pressed-air source to produce nitrogen at amounts to 500 mL/minute with purity of 99.9995 percent, and indus- trial nitrogen gas generators from Parker (
www.parker.com) can pro- duce as much as 99.9995 percent pure compressed nitrogen gas from nearly any compressed air supply. Still, some SMT manufacturers
may prefer to receive inert gas, such as nitrogen, in canisters, and gas sup- pliers such as Praxair (
www.prax -
air.com) offer 99.9999 percent grade nitrogen in a number of different cylinder types, including AS, T, and AQ cylinders. The gas content (in cubic feet per cubic meter) varies according to cylinder as does the product grade and quality assay spec- ification (amounts of other gases con- tained in the cylinder). For example, a product grade specified as “oxygen free” contains less than 0.5 ppm oxy- gen gas. For SMT manufacturers consid-
ering whether a shift to a nitrogen atmosphere can be a benefit, perhaps the most essential consideration is
Progressive Cavity Pumps Provide Precise, Even Dispensing
Continued from previous page
cation, some degree of material heat- ing will most likely be needed. Heating material to a specific tem- perature ensures a consistent shot each time, removing environmental factors and variations in viscosity. Some materials act adversely
when they are not properly degassed or de-aired. If the final product can- not contain any gas or air bubbles, the material must be de-gassed prior to dispensing. Degassing removes bubbles, entrapped air, and gas, and prevents blemishes in the materials. A desiccant dryer or nitrogen blanket removes and guards against mois- ture from a dispensed material. The dry air is monitored so the desiccant dryer can be replaced when it reach- es its limit. In a properly designed dryer, it should be possible to easily swap the dryer while maintaining an uninterrupted drying process. Ultimately, the performance of
a metering/mixing/dispensing sys- tem can impact the success of any business that relies on accurate, tightly controlled dispensing of materials. When considering options available in metering/mixing/dis- pensing systems, the benefits of the advanced capabilities provided by PC pump technology are clear — especially when combined with the use of a flexible and powerful materi- al management system. Contact: FRC-Fluid Research
Corp., 15775 Gateway Circle, Tustin, CA 92780 % 714-258-2350 fax: 714-258-2352 E-mail:
sales@fluidresearch.com Web:
www.fluidresearch.com r
Production reflow ovens such as this BTU Pyramax have zones specifically designed to accept inert Nitrogen gas during reflow.
whether high reliability or low cost is more important. Obviously, produc- ing and supporting a nitrogen atmos- phere in production, whether from gas generators or from stored com- pressed gas canisters, is an added cost compared to a production process without nitrogen. While manufacturing SMT products in a nitrogen environment can improve reliability, it will also result in high- er manufacturing cost. Nitrogen can also benefit a new
manufacturing process and one that tends to be low in volume, compared to not using nitrogen in a more mature manufacturing process and one that has already been proven for high volumes.
Page 61
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