Juan:

For a "It depends." (I hate saying that.)

From a compliance side, It depends on what would fly in the face of an audit. If you check level daily and record the level, would that be "good enough?" That would depend on your area. In southern California where I live and work, weather of any kind beyond sunshine is an anomaly and a daily verification may be sufficient. However, in other locations where weather can change by the minute it likely would not be considered sufficient. It also depends on what you are manufacturing. For high reliability (e.g. space) applications a (recording) continuous monitoring would be the expected norm and would prove that an assembly area has no potential ESD concerns caused by low humidity. Most companies I have worked at (high reliability) stop work at 30% humidity for ESD issues. Some internal standards I have worked to allow working up to 70% humidity. Above that level mechanical assembly could be impacted due to the issue of rust.

From a metallurgical perspective, I have no direct knowledge of a humidity affecting soldering operations, but that is not my area of expertise. But I am thinking of sailors soldering on the high seas performing rework on shipboard electronics and naval avionics. But from a process control perspective any environmental change can affect soldering process (e.g. barometric  pressure). Now that I said something I am sure more knowledgeable folks will chime in.

Gregg

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Juan T. Marugan
Sent: Wednesday, October 28, 2015 1:36 PM
To: [log in to unmask]
Subject: [TN] J-STD-001: Humidity control

I am a little confused regarding the requirement stated in J-STD-001 for the humidity level in the facility.

Reading the standard, I understand that the value of 30% RH (minimum) is only referred to prevent damages induced by an electrostatic discharge, but not for soldering. Is it correct? Of course, the soldering process shall meet all the requirements and also the solder joints.

And a last question. Does the J-STD-001 require keeping records of the readings of temperature and humidity in the assembly workshop? Is it acceptable a system that starts to work when the humidity drops to a certain level (for example 40%) even if that system does not have the possibility to save these data?


Thank you.


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