Europejskie Centrum Integracji i Rozwoju

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Surface mount printed wire board welding


Reflow is heating source (such as electric wire) baking hot plate,[link widoczny dla zalogowanych], hot plate to heat conduction heat transfer directly to the main board printed wire welding. The advantage is abnormal single device can control the temperature and low cost. Suitable for small batch production. The disadvantage is easily oxidized spot, only for ceramic substrates. Not suitable for double-sided welding. Laser reflow of solder joints using focused laser Cambodia Canada 'hot, melting the solder paste saw to complete the welding. ■ dig their equipment manufacturing complex, high investment,[link widoczny dla zalogowanych], low productivity. But it can account ● computer under the control of selective heating of the solder joints are particularly suitable for soldering temperature-sensitive device and solder joints on the repair of a man. Figure 7 is the working principle of hot air reflow diagram, the wind won five of the furnace heat: ~ fq-hair, the hot air blowing printing line conveyor channel, enabled the line board temperature rise. Compared with the infrared furnace, hot stove there is no radiation. Shadow. Each heating zone temperature uniformity is good, warming fast, responsive temperature control range, low equipment prices lower bad solder joints. But some foreign selling in the stove in our price is not low. Fh in the stove board within the print line of flux, solder may be due to air flow too fast and flying, so the stove in Figure 7 preheating zone and the addition of a welding zone infrared heating panels, in order to increase the temperature effect, to avoid the high winds. How to take measures to overcome this defect. Companies are stepping up research and improvement. Generally required cleaning after soldering, the production there are three approaches: using ordinary Tao cleansing lotion, with a special cleaning agent, not cleaning. Common cleaning agents in the 7O's alcohol ketone ● before,[link widoczny dla zalogowanych], now we use Freon. Fh environmental pollution in the Freon, now phase out the use of international research is widely se l charge of their substitutes, and has made some progress. Special cleaning agent by the solder manufacturer to offer highly targeted. Water cleaning is a prerequisite for welding. Must be water-soluble flux. Now after wave of foreign water cleaning process has been popular in China just trial. There '● Preheat {2 Zone District, l l3 l4 area and then circle 7 濞 hot debate to defend the diagram again 浼 products are higher, and to strengthen the washing effect, plus the sprinkler, heating, ultrasonic vibration and other auxiliary means. The development of non-cleaning solder profile. Paid utility developed industrial countries. General flux accounted for 25-40% of solid components, welded wire left in the Indian board,[link widoczny dla zalogowanych], it must be cleaned. Now developed a low amount of solid homes flux, its hard to volatile solids only 5% of the total weight of divination, so after welding if required, is not too high. Can not clean. This regard, research is continuing. At present, for the most demanding products. Also can not wash, T is the solder used in solder paste powder and flux Taijin uniform and stable mixture and added a special solder alloy powder to prevent precipitation of the emulsion gel suspension. In order to meet a variety of welding applications, the solder alloy particles shape, size. Flux content. Viscosity can be dubbed a variety of components. Solder paste applied to copper, tin, lead, silver, gold, palladium, platinum, nickel, steel. Welding aluminum and its alloys, as long as the change in formula only. Circuit designers to note what kind of equipment used in production which welding. Components will affect the arrangement of printed wire board layout. Hybrid assembly (that is, part of the chip components, some leaded components mounted on a printed line with the board) of the Indian line of boards, must be soldered using wave soldering. In this case, the arrangement of orientation of the surface mount components to be carefully designed, because the components parallel or perpendicular to the transmission direction of welding, the result is very different. When the device was heard from the very hour, peak flow will cross the distance of tin, resulting in device ends of the smell of the bridge. In addition, interest in India line between the pad and the component ends, in order to accumulate enough solder to make a good weld, the pad should be multi-component extension of more than ends. If you do not design. Wave soldering of these contacts jet stream, the step due to the bad welding solder fireflies. In another case of fishing 【solder, solder in the solder coating on the pad before been on: the components and the lower ends of the press to defend the plate in the reflow furnace by melting high temperature solder weld,[link widoczny dla zalogowanych], so defend disk components do not extend to the outside ends. Also, due to the amount of solder coating is accurate, easy to components in the pad or between the bridge between the ends. Therefore, the use of reflow soldering method, allowing closer layout arrangement of these components. For example, SOIC parallel to the pad near the minimum spacing of up to 0.3ram. Components to be listed in detail the arrangement of the example layout and welding is very laborious. Designers should pay attention to the use of a series of printed lines recommended graphics board pad design and size. And understand their own design when products are used in welding which, so make design more reasonable, to achieve a multiplier effect. - 157 a I ●
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