Etville, 20.03.2016
Exactly one year ago, at SMT 2015, Emil Otto GmbH presented its environmentally friendly Green-Line flux series for the first time. The Green-Line series from Emil Otto includes various water-based fluxes for wave soldering. Due to the fact that the demand for ecological fluxes increased within this year, Emil Otto GmbH decided to complete the range of water-based fluxes. As selective applications are becoming increasingly popular, Emil Otto wanted to offer a water-based selective flux that had been tested under practical conditions.
"The advantages of these environmentally friendly fluxes are obvious," explains Markus Geßner, authorized signatory of Emil Otto GmbH. Water-based fluxes are not flammable. Alcohols, on the other hand, have a flash point of 12°C and are therefore highly flammable. This results in advantages in production, transportation, storage and handling, as these products are not subject to dangerous goods classification.
The company examined various options with system manufacturers. The focus here was on preheating. The flux structure and the device configuration had to ensure that the circuit board was dry at the time of soldering, that the flux had sufficient activity and that no moisture residue remained on the circuit board.
A system concept was selected based on these specifications. The flux was dosed via drop application. The flux quantity can be precisely dosed by means of pre-pressure, the transport speed and the nozzle opening time. Both silver-containing and silver-free standard alloys were used as solder in the test phase. The dwell time and radiation intensity could be controlled in a separately controllable preheating area, which was equipped with infrared radiators. The temperature on the top of the circuit board was measured after completion of the preheating phase.
Both activated and single-sided nozzle attachments were used as mini shafts in the test phase. The mini-shafts were also nitrogen-fluxed. A EURO test circuit board from Emil Otto GmbH with HAL, chemical tin and nickel-gold was used for the test runs. At the beginning of the test, however, reference values had to be recorded in a basic setting.
Hierzu wurden die Anlagenparameter bezüglich der Testplatine HAL und dem EO-Flussmittel „RS-4004“, Typ 2.2.3.A, ermittelt. Dieses alkoholbasierende Flussmittel erfüllt die Anforderungen gemäßDIN EN 61 190 1 1 und auch die Anforderungen des EO-Haustests, basierend auf Untersuchungen des Fraunhofer Institutes Oberpfaffenhofen zum SIR-Verhalten nicht thermisch belasteter Flussmittelrückstände. Die so gewonnenen Anlagenparameter bezüglich der Flussmittelmenge, der Vorheizungsverweilzeit und der Strahlenintensität, der Höhe und der Verweilzeit der Miniwelle sowie des Stickstoffstroms an der Miniwelle wurden als Grundeinstellung und Referenz festgelegt. Auf eine Optimierung wurde bewusst verzichtet.
Comparative tests were then carried out with various alcohol-based and partially aqueous fluxes. The results showed only slight fluctuations. A water-based VOC-free flux was then tested under the same conditions. The water-based flux "EO-G-001", classified according to DIN EN 61190-1-1: OR/L0 or type 2.1.3.A according to ISO 9454, was developed by Emil Otto for this purpose. This halogen-free flux fulfills all the criteria described above with regard to surface resistance.
Depending on the machine type, temperatures of 90°C to 130°C were measured on the top of the PCB after preheating. The PCBs were dry, as in the comparative tests with non-water-based fluxes. Due to the surface tension of the water, the flux spread over a smaller area than with the alcohol-based fluxes. The penetration and pad wetting were not negatively affected and the soldering results were more than satisfactory. The cleanliness was just as good and in some cases better than with the alcohol-based fluxes.
"With the water-based Emil Otto flux "EO-G-001", very good results were achieved in selective soldering on various machines from different manufacturers. Both the soldering results and the cleanliness of the circuit board were very good. We therefore offer our users both water-based fluxes for wave and selective soldering in our "Green Line" range. We have closed this product gap and can therefore present another new product at this year's SMT," summarizes Geßner with satisfaction.
The Emil Otto stand is located in Hall 7A, Stand 505.