We had an ISO finding where paper was on top of circuit boards and I am trying to convince management to invent in ESD sleeves for our production process. Management isn’t happy with the pricing of the ESD sleeves and are wanting to find an alternate solution without drastically changing our current process. I know I have read that paper touching pcb/sensitive devices is a risk and i’ve seen the documents for specs on ESD sleeves. Do any of the standards specifically state the requirements for regular paper if it is going to be next to a pcb? I was thinking that the requirement would be that the paper would have to be inside a ESD package that would contain any static buildup and had to be sealed on at least three sides. One of the suggestions I was given was an ESD clipboard, but the paper would be completely exposed on the top
Would it be possible to use the static shielded bags or the cheap pink antistatic bags? The paper would go inside and that would be placed directly on the circuit board or between two circuit boards.
Josh,
There is no specific ESD requirements for paper on top of circuit boards other than the requirement in ANSI/ESD S20.20, section 8.3.1 on insulators:
• Measure the field at the location where the ESDS item is handled. The electrostatic field shall be less than 5000 volts/meter (125 volts/inch).
or
• For any process essential insulators located less than or equal to 25 mm from an unprotected ESDS item, the voltage on the surface of the insulator shall be less than 125 volts when measured with a non-contact electrostatic voltmeter. When using an electrostatic field meter, the reading shall be less than 125 volts when measured at the meter’s stipulated measuring distance.
• For any process essential insulators located more than 25 mm, but less than 300 mm from an unprotected ESDS item, the voltage on the surface of the insulator shall be less than 2000 volts when measured with a non-contact electrostatic voltmeter. When using an electrostatic field meter, the reading shall be less than 2000 volts when measured at the meter’s stipulated measuring distance.
Most paper have resistances under the insulative range (<10^9 ohms), but you should always verify it.
Since you intend on putting the paper on the circuit board, I recommend using the first method. If you measure the electric field at the circuit board, with the paper present and you don’t see anything over 125 volts/inch, you should be fine