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SMT Production Floor & Component Store/ware house RH Control

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#46687

SMT Production Floor & Component Store/ware house RH Control | 15 January, 2007

Dear Friend, Our SMT Production & component ware house RH currently control limit set to 40%RH - 60%RH, but not always achievable, the RH reading measurement are between 38%RH -65%RH. J-STD-001D recommend 30%RH - 70%RH. However it is only a recommendation and not a requirement. Anyone can comment 38%RH - 65%RH is good enough or need more restrictive RH control for SMT or MSD purposes? Beside, J-STD any others standard have specify the RH control requirement? Thanks

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#46688

SMT Production Floor & Component Store/ware house RH Control | 15 January, 2007

ANSI-J-STD-001: 18-30�C, 30-70%RH * If out of range, shall verify electrostatic discharge control program according to ANSI/ESD S20-20 is adequate. * For process control, more restrictive temperature and humidity limits may be required.

ANSI/ESD S20-20-1999, Table 1- ESD Control Program Technical Requirements Summary: Reference Paragraph||Implementing Process or Method||Area 1 Mfg.||Area 2 Field||Test Method, Standard or Advisory||Recommended Range5 - ||Humidity||Optional implementing process or method||Optional implementing process or method||N/A||> 30% Rh < 70%6 5 The values in the Recommended Range are obtained by using the Test Method, Standard or Advisory provided in this table. See paragraph 6.2 for further guidance regarding alternate test methods. 6 This is a proposed value that has not been substantiated by any standard.

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#46693

SMT Production Floor & Component Store/ware house RH Control | 16 January, 2007

Hi,

If you need to get a humidity target, the best way is to run the air conditioning plant very cold, which will drop the moisture out of the air, and then you can reheat to the required temp, and install humidifiers to re humidify the air to the required humidity point.

This is the way to achieve an accurate humidity level.

Regards,

Grant

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#46910

SMT Production Floor & Component Store/ware house RH Control | 23 January, 2007

Here in the Great White North, the best way to check our CM's compliance with the ESD 20.20 is to take a couple months worth of data during heating season and graph it against the outside temp swings. You can easily see how the HVAC system keeps up, especially when the temp drops below 0. We have seen 17% RH at times and that is a huge red flag.

Don't forget to check the warehouse area and any offsite storage for compliance. The warehouses are usually the last areas to get attention from an HVAC perspective.

I also need to audit for ESD controls at the same time to asses complete risk. If the RH is less than 30% and the ESD controls are sketchy, that is a huge risk. As a OEM, ESD risk = field failures so mitigation on the front end is imperative.

The best fix is active humidification via steam emitters or water ionizers ( cold system ) with active feedback controls. I would be interested to hear other folks control plan for RH.

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Grant

#46911

SMT Production Floor & Component Store/ware house RH Control | 23 January, 2007

Hi,

I ran a clean room once, and the humidifiers were built into the exit air ducts, and controlled by a humidity control unit that kept things at 60%. We were loading VHS tapes, and needed to keep humidity at that level or static discharges caused by winding the video tape at high speed would cause damage to the tape, and an increase in drop outs.

Humidity control should be something any clean room air conditioning company could advise on, even if you don't need low particle count environments.

Regards,

Grant

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