There are problems with the two components of the chip processing?

Generally, when smt processing is applied, it is necessary to take into account that there is a certain error in the placement of the machine, and considering the ease of maintenance and visual appearance inspection, the adjacent two components can not be too close, and a certain safety distance is required. So how close are the two components?

In addition to ensuring a safe spacing between pads that are not easily shorted, the maintainability requirements of consumable components should also be considered. The general assembly density requirements are as follows:

1. Between the chip components, between the SOTs, between the SOIC and the chip components is 1.25 mm;

2. Between SOIC, between SOIC and QFP is 2mm:

3. The PLCC is 2.5mm between the chip component, SOIC and QFP:

4. 4mm between PLCC.

5. In hybrid assembly, the distance between the interposer component and the chip component pad is 1.5 mm.

6. When designing the PLCC socket, pay attention to the size of the PLCC socket body (because the PLCC pin is on the inside of the bottom of the socket body).

Component layout rules

Under the condition of design permission, the layout of components in smt processing is as close as possible to the same components in the same direction, and the modules with the same function are arranged together; the components of the same package are placed at equal distances for component placement, Welding and testing.

Safety distance between components

QFP, PLCC. The common feature of these two devices is the four-lead package, the difference is that the lead shape is different. The QFP is a gull-wing lead and the PLCC is a J-shaped lead. Because it is a four-sided lead package, the wave soldering process cannot be used.

QFP and PLCC devices are usually placed on the component surface of the PCB. If they are to be placed on the soldered surface for secondary reflow soldering, the weight must be such that the load-bearing surface per square inch of the solder joint contact surface should be less than or equal to 30 grams.

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