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SMT processing has the basic elements, namely, screen printing, assembly, welding, cleaning, testing and maintenance, screen printing equipment is used in screen printing machine, SMT mainly use post installed, connected components and printed circuit board is fixed, when the equipment is required for the solidifying furnace, make the adhesion between the components and circuit board more solid. In addition, in the process of any one link can be set up a pit, in order to found defective products in time, reduce the defect product goes to the market.

Products are divided into several series can be used in SMT processing, including wireless communications series, series of household electrical, electronic toys and computer peripheral series. Specific products include cordless phone motherboard, wireless can system board, DVD, wireless business telephone system board, DVD servo board, CD, DVD decoder board, MP3 system board, car audio, remote control cars, repeater board, remote control aircraft, doraemon, mini radio, network card, graphics card, U disk, mouse board and other products.

When using the SMT process, must pay attention to the standard operation and the safety of operators. The first thing to understand the electrostatic discharge of measures, including SMT processing design intent and to establish a good standard. At the time of SMT processing, keep sensitive to electrostatic discharge, and then aiming at the problem of electrostatic discharge prone to put forward the treatment method and corresponding operating personnel protective measures. If these standards do not understand, that is about to study related literatures.

SMT processing to meet the criteria for the assessment of welding, the welding SMT processing, one of the basic link of welding including common welding and hand welding. Welding in SMT processing chain, according to the standard of reference to correct selection of welding methods, not based on subjective judgment to decide, in general can consult to determine the assessment manual. Some technical content higher factory has also to 3 d building products, in order to produce a more beautiful, more standard products.

Advantages of SMT processing

1. High assembly density

Chip components than conventional perforation components are greatly reduced size and quality. Generally, the SMT can make electronic product volume decreased 60%, the quality to reduce 75% hole installation technology components, and assemble the components SMT processing grid from 1.27 MM to 0.63 MM grid at present, individual 0.5 MM grid installing component, the density is higher. For example, a 64 pin DIP integrated block, its assembly area of 25 mmx7mm, but also lead the lead spacing is 0.63 MM, the assembly area of 12 mmx12mm, 1/12 of the area of hole technology .

2. High reliability

Because of the chip components of high reliability, small devices and light, so the seismic capability is strong, using automated production, with high reliability, generally poor solder joint rate is less than ten over one million, lower than the hole plugging component wave soldering technology, an order of magnitude in SMT processing and assembly of electronic products MTBF for an average of 250000 hours, at present nearly 90% of the electronic products SMT process.

3. Good high-frequency characteristics

Because the chip components in solid device, usually without lead or short fuses, reduce the effect of the parasitic inductance and stray capacitance, improve frequency characteristic of the circuit, by SMC and SMD design the circuit of the highest frequency of 3 GHZ, and use only a few components for 500 MHZ using the time of transmission delay. Can be used for the clock frequency circuit for more than more than 16 MHZ. If using MCM technology, the computer workstation high-end clock frequency is 100 MHZ, caused by a parasitic reactance additional power consumption can reduce 2-3 times.

4. Cut costs

A: the use area of the printed circuit board is reduced, the area is 1/12 of the through-hole technology, if the use of CSP installation, the area will be greatly reduce

B: the number of boreholes on the printed board is reduced to save the repair cost;

C: the circuit debugging cost is reduced due to the improvement of frequency characteristics;

Because of the small size and light weight of the chip components, the packaging, transportation and storage costs are reduced.

SMC and SMD development is fast, the cost of rapid decline, a chip resistor with through-hole resistor price equivalent, about one yuan

5. Easy to automate production

The punch installation PCB to achieve fully automated, still need to expand 40% original PCB area, so that the automatic plug-in instrumentation head insert element, there is no enough space gap, to touch the bad parts. Automatic placement machine (SM421 / SM411) adopts vacuum suction mouth put components, vacuum suction nozzle is less than the element shape, indeed improve the installation dimension. In fact small components and fine pitch QFP device adopt automatic placement machine for production, in order to realize full automation production.