SMT room environment

68 to 72F, 25 to 30% humidity. IPC might have exact numbers.

reply »

A review document for J-STD-001F with Amendment 1 had the following wording, but you should check the actual document to be sure of correctness

4.2 Facilities Cleanliness and ambient environments in all work areas shall [D1D2D3] be maintained at levels that prevent contamination or deterioration of tools, materials, and surfaces to be soldered or conformally coated. Eating, drinking, and/or use of tobacco products shall [D1D2D3] be prohibited in the work area.

4.2.1 Environmental Controls The soldering facility should be enclosed, temperature and humidity controlled, and maintained at a positive pressure.

4.2.2 Temperature and Humidity When humidity decreases to a level of 30% or lower, the Manufacturer shall [N1D2D3] verify that electrostatic discharge control is adequate. For process control, more restrictive temperature and humidity limits may be required.

4.2.2.1 Temperature For operator comfort and solderability maintenance, the temperature should be maintained between 18°C [64.4°F] and 30°C [86°F].

4.2.2.2 Humidity The range (lower and upper limits) of humidity in the assembly area shall [N1D2D3] allow soldering (including solderability maintenance) and assembly materials to function correctly in the process, based on vendor recommendations or documented evidence of process performance. For operator comfort the relative humidity should not exceed 70%. See 3.8 for humidity control requirements for moisture sensitive devices/assemblies.

4.2.3 Lighting Illumination at the surface of workstations should be at least 1000 lm/m2 (approximately 93 foot candles). Supplemental lighting may be necessary to assist in visual inspection. Light sources should be selected to prevent shadows on the item being inspected except those caused by the item being inspected. Note: In selecting a light source, the color temperature of the light is an important consideration. Light ranges from 3000-5000° K enable users to distinguish various printed circuit assembly features and contaminants with increased clarity.

4.2.4 Field Assembly Operations In field assembly operations on Class 3 products where the controlled environmental conditions required by this standard cannot be effectively achieved, precautions shall [N1N2D3] be taken to maximize the quality of solder connections and minimize the effects of the uncontrolled environment on the operation being performed on the hardware.

reply »