As an important part of a system, PCB has a very close relationship with the above.
It needs to be specially noted that there are many clauses about safety signs and safety instructions in relevant standards. Here are only some clauses related to PCB design, commissioning, installation and maintenance process to attract special attention. If formal safety testing or certification is required, it should also be based on formal standards.
1.2 safety signs
1.2.1 general criteria for safety signs
The safety signs used on PCB should conform to the general criteria of safety signs.
The language acceptable to the country where the PCB belongs should be used.
The required mark should be durable and eye-catching. Considering the durability of the mark, the influence of normal use should be taken into account.
Check whether it is qualified by checking and controlling the mark. When controlling the mark, wipe it by hand with a cotton cloth dipped in water for 15 seconds, and then wipe it by hand with a cotton cloth dipped in gasoline for 15 seconds. After the experiment, the mark should still be clear, and the label plate should not be easily removed, and there should be no curling.
1.2.2 risk of electric shock and energy
On PCB board, the pins of components are exposed on the surface, which is very likely to cause electric shock or energy hazard.
In order to prevent the occurrence of electric shock or energy hazard, any place on PCB board that may have electric shock or energy hazard, such as ELV circuit part, primary circuit part, secondary circuit part with safe voltage but reaching dangerous energy level, etc., should be marked with obvious marks; The place where electric shock or energy hazard may occur may be in the accessible area of the operator, and the page may be outside the accessible area of the operator; The content of the sign should indicate that it has exceeded the dangerous energy level, and should be accompanied by danger warning signs;
1.2.3 fuse on PCB
Each fuse holder or nearby shall be marked with the rated current, fusing characteristics (slow, fast, time lag) and explosion-proof characteristics (low breaking, high breaking). If the fuse holder can be installed with fuses with different voltage ratings, the rated voltage of the fuse shall also be marked.
Example: t2.5al, 150V, f3.15ah, 250V
Six complete marks should be added near the fuse, including fuse serial number, fusing characteristics, rated current value, explosion-proof characteristics, rated voltage value, English warning signs, such as f10ah, 250VAC, "caution: for continuous protection against risk of fire, replace only with same type and rating of fuse."
The above are safety considerations in PCB design. If you have more questions about PCB, please consult the company's customers.
