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| PCB design, layout requirements for some special devices |
| 2020-03-07 |
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PCB device layout is not a freewheeling thing, it has certain rules that everyone needs to follow. In addition to general requirements, some special devices also have different layout requirements.
Layout Requirements for Crimp Devices
1) There must be no components higher than 3mm around 3mm of the crimp / male, bend / female crimping device surface, and there must be no soldering devices around 1.5mm; the back side of the crimping device is 2.5 away from the center of the pinhole of the crimping device There must be no components within the range of mm.
2) There should be no components around 1mm of straight / male and straight / female crimping devices. When a sheath is required on the back of straight / male and straight / female crimping devices, no element should be arranged within 1mm from the edge of the sheath. For components, no components shall be arranged within 2.5mm from the crimping hole when the sheath is not installed.
3) The live plug of the grounding connector used with the European-style connector, the front end of the long pin is 6.5mm and the short pin is 2.0mm.
4) The long pin of 2mmFB power single PIN pin corresponds to 8mm forbidden cloth at the front end of the board socket.
Layout requirements for thermal devices
1) In the layout of the device, the heat sensitive devices (such as electrolytic capacitors, crystal oscillators, etc.) should be kept as far away from the high heat devices as possible.
2) The thermal sensor should be close to the tested component and away from the high temperature area, so as not to be affected by other heating work equivalent components and cause malfunction.
3) Place the heat-generating and heat-resistant device near the air outlet or on the top, but if it cannot withstand the high temperature, also place it near the air inlet, and try to rise in the air with other heat-generating devices and thermal devices Staggered in direction.
Layout requirements with polar devices
1) THD devices with polarity or directionality are aligned in the same direction and arranged neatly.
2) The orientation of polar SMC is as consistent as possible on the board; devices of the same type are arranged neatly and beautifully.
(Polar devices include: electrolytic capacitors, tantalum capacitors, diodes, etc.)
Layout requirements for through-hole reflow devices
1) For PCBs with a non-transmitting edge size greater than 300mm, heavier components should not be placed in the middle of the PCB as much as possible to reduce the impact of PCB component deformation on the PCB deformation during the soldering process, and Effects of placed devices.
2) To facilitate insertion, the device is recommended to be placed near the operation side of the insertion.
3) It is recommended that the length of longer devices (such as memory sockets) be consistent with the transfer direction.
4) The distance between the edge of the pad of the through hole reflow soldering device and the QFP, SOP, connector and all BGAs with pitch ≤ 0.65mm is greater than 20mm. The distance to other SMT devices is> 2mm.
5) The distance between the body of the through-hole reflow soldering device is> 10mm.
6) The distance between the edge of the pad of the through-hole reflow soldering device and the transmission side is ≥10mm; the distance from the non-transmission side is ≥5mm.
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