Detailed explanation of the layout requirements of special devices in PCB design

PCB device layout is not an arbitrary thing, it has certain rules that need to be followed by everyone. In addition to general requirements, some special devices also have different layout requirements.

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Layout requirements for crimping devices

1) There should be no components higher than 3mm 3mm around the curved/male, curved/female crimping device surface, and there should be no welding devices around 1.5mm; the distance from the opposite side of the crimping device to the pin hole center of the crimping device is 2.5 There shall be no components within the range of mm.

2) There should be no components within 1mm around the straight/male, straight/female crimping device; when the back of the straight/male, straight/female crimping device needs to be installed with a sheath, no components shall be placed within 1mm from the edge of the sheath When the sheath is not installed, no components shall be placed within 2.5mm from the crimping hole.

3) The live plug socket of the grounding connector used with the European-style connector, the front end of the long needle is 6.5mm forbidden, and the short needle is 2.0mm forbidden.

4) The long pin of the 2mmFB power supply single PIN pin corresponds to the 8mm forbidden cloth at the front of the single board socket.

Layout requirements for thermal devices

1) During device layout, keep thermal sensitive devices (such as electrolytic capacitors, crystal oscillators, etc.) as far away from high-heat devices as possible.

2) The thermal device should be close to the component under test and far away from the high-temperature area, so as not to be affected by other heating power equivalent components and cause malfunction.

3) Place the heat-generating and heat-resistant components near the air outlet or on the top, but if they cannot withstand higher temperatures, they should also be placed near the air inlet, and pay attention to rising in the air with other heating devices and heat-sensitive devices as much as possible Stagger the position in the direction.

Layout requirements with polar devices

1) THD devices with polarity or directionality have the same direction in the layout and are arranged neatly.

2) The direction of the polarized SMC on the board should be as consistent as possible; the devices of the same type are arranged neatly and beautifully.

(Parts with polarity include: electrolytic capacitors, tantalum capacitors, diodes, etc.)

Layout requirements for through-hole reflow soldering devices

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1) For PCBs with non-transmission side dimensions greater than 300mm, heavier components should not be placed in the middle of the PCB as far as possible to reduce the influence of the weight of the plug-in device on the deformation of the PCB during the soldering process, and the impact of the plug-in process on the board. The impact of the placed device.

2) In order to facilitate the insertion, the device is recommended to be arranged near the operation side of the insertion.

3) The length direction of longer devices (such as memory sockets, etc.) is recommended to be consistent with the transmission direction.

4) The distance between the edge of the through-hole reflow soldering device pad and the QFP, SOP, connector and all BGAs with a pitch ≤ 0.65mm is greater than 20mm. The distance from other SMT devices is> 2mm.

5) The distance between the body of the through-hole reflow soldering device is more than 10mm.

6) The distance between the pad edge of the through-hole reflow soldering device and the transmitting side is ≥10mm; the distance from the non-transmitting side is ≥5mm.