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Significant cost loss and difficulties in SMT patch and solutions
PCBA Tech
Significant cost loss and difficulties in SMT patch and solutions

Significant cost loss and difficulties in SMT patch and solutions

2021-11-10
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Author:Downs

Significant cost loss in SMT patch

 The component consumption rate has risen recently, and customer satisfaction has also had a corresponding impact. This is why we are concerned about the significant cost loss of SMT today. Now that we have found the problem, we will analyze the factors other than the shortage of manpower in the attitude of serving customers. I hope that if you have similar problems on the production line, we can help you!

1. High throwing rate

1. The machine lacks maintenance and repair. Because the surface of the nozzle is stained, the nozzle cannot recognize the material or the recognition is poor.

2. Insufficient air compressor pressure, or insufficient storage capacity of the vacuum compression pump of the placement machine, resulting in material throwing during the placement process.

3. The braid of the feeder has insufficient crimping force, which causes the plastic bag to not crimp normally during the feeding process.

4. There is an error in the editing of the placement program, and the PCB MARK coordinate setting is wrong, which causes the feeding position to be incorrect.

5. Deviation occurs during solder paste printing, the printing position of solder paste is shifted, and the material cannot be welded.

pcb board

6. The flatness of the workbench and the support platform is not in the same horizontal plane or error in the debugging equipment.

The high discards prove that the patch loss is large, and the loss is large, and it needs to be refilled, refilled, and refilled, any of which needs to consume costs.

Especially the core BGA or IC, because it belongs to the A-level material, the loss and spare parts should be strictly controlled or there are few spare parts. If it is due to the manufacturer's own reasons, the customer's delivery date may not be able to keep up with the corresponding compensation.

Difficulties and solutions in SMT patch processing

 One is high reliability and strong anti-vibration ability

SMT processing adopts chip components, which have high reliability, small size and light weight, so it has strong anti-vibration ability. It adopts automated production and has high reliability. Generally, the rate of bad solder joints is less than ten and more than one million, which is lower than wave soldering technology. In order to ensure a low defect rate of solder joints of electronic products or components, nearly 90% of electronic products currently use SMT technology.

Second, electronic products are small in size and high in assembly density

The volume of the patch component is only about 1/10 of the traditional insert component, and the weight is only 10% of the traditional insert component. Generally, surface mount technology can reduce the volume of electronic products by 40% to 60%, the mass by 60% to 80%, and the area and weight are greatly reduced. The SMT processing grid of assembled components is currently from 1.27mm to 0.63mm grid, and the single grid is 0.5mm. The installation of hole process components can make the packaging density higher.

Third, high-frequency characteristics, reliable performance

Because the chip components are firmly connected, the devices usually have no leads or short leads, which reduces the influence of parasitic inductance and parasitic capacitance, improves the high-frequency characteristics of the circuit, and reduces electromagnetic interference and radio frequency interference. The frequency of the circuit designed by SMC and SMD can reach 3GHz, while the circuit designed by the chip is only 500MHz, which can shorten the transmission delay time. It can be used in circuits with a clock frequency above 16MHz. Using MCM technology, the clock frequency of the computer workstation can reach 100MHz, and the extra power consumption caused by parasitic reactions can be reduced by 2-3 times.

Fourth, increase productivity and realize automated production

At present, if the perforated printed board is to be fully automated, it is also necessary to expand the area of the original printed board by 40% so that the insertion head can automatically insert the components, otherwise the space gap is not enough and the parts will be damaged. The automatic placement machine (SM421/SM411) uses a vacuum nozzle to suck and discharge components. The vacuum nozzle is smaller than the component, but it improves the installation density. In fact, in the production of automatic placement machines, small parts and small-pitch QFP units are used to achieve full-line production automation.

The fifth is to reduce costs and reduce expenses

(1) The area of the printed board is reduced, which is 1/12 of the through-hole process. If CSP is used for installation, the area is also greatly reduced;

(2) Reduce the number of drilling holes on the printed circuit board and save maintenance costs;

(3) As the frequency characteristics of the circuit are improved, the circuit debugging cost is reduced;

(4) Due to the small size and light weight of chip components, the packaging, transportation and storage costs are reduced;

The use of SMT chip processing technology can save materials, energy, equipment, manpower, time, etc., and can reduce costs by as much as 30% to 50%.